- May 2023
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Using an approach that combines synthetic genetic array (SGA) analysis with high-throughput microscopic analysis of the GFP-tagged yeast ORF collection in the budding yeast, Saccharomyces cerevisiae, this study has examined the contribution of the critical checkpoint kinases Mec1 and Rad53 to the subcellular relocalization of 322 candidate proteins in response to HU- and MMS-induced replication stress. Previous studies have established that Mec1 is required for Rad53 activation during replication stress and that Mec1 also serves checkpoint functions independent of Rad53. Unexpectedly, this study identifies groups of proteins whose stress-induced relocalization is dependent on Rad53 but not Mec1. This data indicates that Rad53 mediates some replication stress responses in a non-canonical manner that is independent of Mec1.
The authors confirm their initial observations from the screening approach by focusing on the Rad53-dependent and Mec1-independent focus formation of GFP-Rad54. Moreover, using mass-spec analysis the authors demonstrate that some Rad53 phosphorylation sites known to be critical for Rad53 activation, including a consensus Mec1 phosphorylation site, are phosphorylated after replication stress even in the absence of Mec1. Motivated by this finding the authors screen for potential kinase and phosphatase pathways that may regulate Rad53 function during MMS-induced replication stress. Top hits identified include members of the retrograde signaling pathway, which is confirmed by conventional genetic assays while mass spec analysis supports the involvement of Rtg3 in mediating Rad53 phosphorylation during replication stress in the absence of Mec1.
Overall this is a solid study reporting unexpected new findings that significantly advance our view of the global replication checkpoint response. The data are generally of high quality, well presented and quantified, and overall support the authors' claims. The mass spec approach used here to identify Rad53 phosphorylation sites offers an unbiased alternative to the simpler and more widely employed gel-shift method to monitor Rad53 activation. The hits identified in the various screens presented here provide a platform for potential follow-up studies by the community. The main drawback is that it remains unclear how Rtg3 promotes Rad53 activtation. However, this could be considered to be beyond the scope of this study.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The relationship between measures of brain state, behavioral state, and performance has long been speculated to be relatively simple - with arousal and engagement reflecting EEG desynchronization and improved performance associated with increases in engagement and attention. The present study demonstrates that the outcome of the previous trial, specifically a miss, allows these associations to be seen - while a correct response appears less likely to do so. This is an interesting advance in our understanding of the relationship between brain state, behavioral state, and performance.
While the study is well done, the results are likely to be specific to their trial structure and states exhibited by the mice. To examine the full range of arousal states, it needs to be demonstrated that animals are varying between near-sleep (e.g. drowsiness) and high-alertness such as in rapid running. The fact that the trials occurred rapidly means that the physiological and neural variables associated with each trial will overlap with upcoming trials - it takes a mouse more than a few seconds to relax from a previous miss or hit, for example. Spreading the rapidity of the trials out would allow for a broader range of states to be examined, and perhaps less cross-talk between adjacent trials. The interpretation of the results, therefore, must be taken in light of the trial structure and the states exhibited by the mice.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript by Mohebi et al. examines a critical open question regarding the interaction of cholinergic interneurons of the striatum and transmitter release from dopaminergic axons in behaving animals. Activation of cholinergic interneurons in the striatum can evoke dopamine release in brain slices and in vivo as measured with voltammetry. However, it remains an open question in what context and to what extent this acetylcholine-mediated dopamine occurs in behaving animals. Here, the authors argue that CIN activity triggers dopamine release in the nucleus accumbens which encodes the motivation to obtain a reward through increasing "ramps" of dopamine release. Their data suggest that the ramps are not reflected in the firing of dopaminergic neurons. Rather, they provide compelling evidence that the ramps of dopamine release correlate with ramps in cholinergic interneuron activity as measured with GCaMP6. What's more, the authors show that ACh-mediated dopamine release has no paired-pulse depression, a striking result that differs from all prior ex vivo brain slice data. The manuscript is extremely well written and the data are of very high quality. Overall, this study represents an important step forward in our understanding of how ACh-mediated dopamine release regulates behavior, and more broadly how axons can generate behaviors independently from somatic activity.
Major comments<br /> 1. The complete absence of any short-term plasticity in CIN-mediated dopamine release is a striking result that is important for the field. The authors should strengthen this result with additional quantitative analysis demonstrating the lack of STP. They have analyzed paired-pulse ratios, but they should analyze this for stimuli at the higher frequencies (4 Hz, etc) that are more physiologically relevant. For example, Fig 1e shows a CIN-evoked DA release at many optically-stimulated frequencies. The authors should quantify short-term plasticity by generating fits of the single stimulus signal and comparing the mathematical sum predicted from 4 stim DA signals at different frequencies to the recorded data. A similar analysis has been done with Ca signals (Koester and Sakmann, 2000).
2. The authors show that optical activation of CINs results in DA release as measured by dLight. To clearly establish that these signals are generated by DA release driven by nicotinic receptors (and not a partial effect of some unknown artifact), it would be useful to show that the optical CIN-evoked dLight signals shown in Fig. 1 are inhibited by nicotinic receptor antagonists such as DHbE. This control experiment would significantly strengthen the result shown here.
3. Similarly, the authors show clear correlations between CIN activity and DA release during behavior. The authors should consider determining whether CINs play a causal role in triggering DA release during behavior. For example, does infusion of DHbE in the NAc prevent the light-mediated DA release during behavior? As an alternative hypothesis, some groups have been suggesting that CIN activity has almost no direct influence over DA. Therefore, testing whether a causal relationship exists between CINs and DA release would be an important experiment in addressing these two opposing viewpoints.
4. The ramps that are described in this manuscript are an order of magnitude faster (increasing over 100s of milliseconds) than ramps described in other studies that occur over seconds. In fact, the two signals may be completely different functionally. Discussion of this topic would be helpful.
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- Apr 2023
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en.wikipedia.org en.wikipedia.org
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Catalog cards were 2 by 5 inches (5 cm × 13 cm); the Harvard College size.
Early library card catalogs used cards that were 2 x 5" cards, the Harvard College size, before the standardization of 3 x 5" index cards.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study the authors investigate functional associations made by transcription factor ZMYM2 with chromatin regulators, and the impact of perturbing these complexes on the transcriptome of the U2OS cell line. They focus on validating two novel chromatin-templated interactions: with TRIM28/KAP1 and with ADNP, concluding that via these distinct chromatin regulators, ZMYM2 contributes to transcriptional control of LTR and SINE retrotransposons, respectively.
Strengths and weakness of the study:
- The co-localization of ZMYM2 with ADNP and TRIM28 is validated through RIME, ChIP-seq and co-IP. (Notably, since both RIME and ChIP-seq rely on crosslinking, and the co-IP with TRIM28 required crosslinking due to being SUMO-dependent, only the ZMYM2-ADNP co-IP experiment demonstrates an interaction in the absence of crosslinking).
- It is good that uniquely-mapped reads are used in the ChIP-seq analysis given the interest in repetitive elements. Likewise, though the RT-qPCR data in Fig5 should be complemented by analysis of the RNA-seq data that the authors already have, it seems that the primers are carefully designed such that a single retrotransposon copy is amplified.
- The top-scoring interactors are highly-abundant nuclear proteins: for example, data from the contaminant repository for affinity purification mass-spec data (https://reprint-apms.org/) show that TRIM28 is identified in 466 / 716 AP-MS experiments with a mean spectral count of 16. While this does not indicate that the ZMYM2-TRIM28 interaction is not 'true', it would have been helpful to further dissect the interaction to strengthen this conclusion. For example, it would be nice to see the co-IP (fig 3A) repeated from the cells expressing the ZMYM2 mutant that is no longer competent to bind SUMO (used in the ChIP-seq data of Fig 2). Alternatively - if the model is that ZMYM2 recruits SUMOylated TRIM28 - with well-characterized TRIM28 mutants that lack SUMOylation.
- The transcriptional response using bulk RNA-seq in ZMYM2-depleted cells is rather gene-centric despite the title of the paper being about TE transcription. In fact the only panels about TE transcription are the RT-qPCR data in Fig 5D,F. I may be missing something (and there aren't many details given about the RNA-seq experiments) but why not look at TE transcription in an unbiased way with the transcriptomic data at hand? I appreciate potential hazards of multi-mapping etc but it would be interesting to see at least some subfamily analysis (e.g. using the TEtranscripts tool). On a similar point, why not show some RNA-seq in the genome browser snapshots of the epigenomics - together with a RepeatMasker annotation track of TEs...
While the results broadly support the authors' conclusions, I have the overall impression that the central claim of TE transcriptional regulation by ZMYM2 could be strengthened a lot with some fairly straightforward additional experiments and analyses.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this manuscript, Chen et al. determined the structural basis for pre-RNA processing by Las1-Grc3 endoribonuclease and polynucleotide kinase complexes from S. cerevisiae (Sc) and C. jadinii (Cj). Using a robust set of biochemical assays, the authors identify that the sc- and CjLas1-Grc3 complexes can cleave the ITS2 sequence in two specific locations, including a novel C2' location. The authors then determined X-ray crystallography and cryo-EM structures of the ScLas1-Grc3 and CjLas1-Grc3 complexes, providing structural insight that is complimentary to previously reported Las1-Grc3 structures from C. thermophilum (Pillon et al., 2019, NSMB). The authors further explore the importance of multiple Las1 and Grc3 domains and interaction interfaces for RNA binding, RNA cleavage activity, and Las1-Grc3 complex formation. Finally, evidence is presented that suggests Las1 undergoes a conformational change upon Grc3 binding that stabilizes the Las1 HEPN active site, providing a possible rationale for the stimulation of Las1 cleavage by Grc3.
Several of the conclusions in this manuscript are supported by the data provided, particularly the identification and validation of the second cleavage site in the ITS2. However, several aspects of the structural analysis and complimentary biochemical assays would need to be addressed to fully support the conclusions drawn by the authors.
• There is a lack of clarity regarding the number of replicates performed for the biochemical experiments throughout the manuscript. This information is critical for establishing the rigor of these biochemical experiments.
• The authors conclude that Rat1-Rai1 can degrade the phosphorylated P1 and P2 products of ITS2 (lines 160-162, Figure 1H). However, the data in Fig. 1H shows complete degradation of 5'Phos-P2 and 5'Phos-P4 of ITS2, while the P1 and 5'Phos-P3 fragments remain in-tact. Additional clarification for this discrepancy should be provided.
• The authors determined X-ray crystal structures of the ScLas1-Grc3 (PDB:7Y18) and CjLas1-Grc3 (PDB:7Y17) complexes, which represents the bulk of the manuscript. However, there are major concerns with the structural models for ScLas1-Grc3 (PDB:7Y18) and CjLas1-Grc3 (PDB:7Y17). These structures have extremely high clashscores (>100) as well as a significant number of RSRZ outliers, sidechain rotamer outliers, bond angle outliers, and bond length outliers. Moreover, both structures have extensive regions that have been modeled without corresponding electron density, and other regions where the model clearly does not fit the experimental density. These concerns make it difficult to determine whether the structural data fully support several of the conclusions in the manuscript. A more careful and thorough reevaluation of the models is important for providing confidence in these structural conclusions.
• The presentation of the cryo-EM datasets is underdeveloped in the results section drawing and the contribution of these structures towards supporting the main conclusions of the manuscript are unclear. An in-depth comparison of the structures generated from X-ray crystallography and cryo-EM would have greatly strengthened the structural conclusions made for the ScLas1-Grc3 and CjLas1-Grc3 complexes.
• The authors conclude that truncation of the CC-domain contributes to Las1 IRS2 binding and cleavage (lines 220-222, Fig. 4C). However, these assays show that internal deletion of the CC-domain alone has minimal effect on cleavage (Fig 4C, sample 3). The loss in ITS2 cleavage activity is only seen when truncating the LCT and LCT+CC-domain (Fig 4C, sample 2 and 4, respectively). Consistently, the authors later show that Las1 is unable to interact with Grc3 when the LCT domain is deleted (Fig. 6 and Fig. 6-figure supplement 2). These data indicate the LCT plays a critical role in Las1-Grc3 complex formation and subsequent Las1 cleavage activity. However, it is unclear how this data supports the stated conclusion that the CC-domain is important for LasI cleavage.
• The authors conclude that the HEPN domains undergo a conformational change upon Grc3 binding, which is important for stabilization of the Las1 active site and Grc3-mediated activation of Las1. This conclusion is based on structural comparison of the HEPN domains from the CjLas1-Grc3 complex (PDB:7Y17) and the structure of the isolated HEPN domain dimer (PDB:7Y16). However, it is also possible that the conformational changes observed in the HEPN domain are due to truncation of the Las1 CC and CGT domains. A rationale for excluding this possibility would have strengthened this section of the manuscript.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Caveney et al have overexpressed an engineered construct of the human membrane receptor guanyl cyclase GC-C in hamster cells and co-purified it with the endogenous HSP90 and CDC37. They have then determined the structure of the resultant complex by single particle cryoEM reconstruction at sufficient resolution to dock existing structures of HSP90 and CDC37, plus an AlphaFold model of the pseudo-kinase domain of the guanylyl cyclase. The novelty of the work stems from the observation that the pseudo-kinase domain of GC-C associates with CDC37 and HSP90 similarly to how the bona fide protein kinases CDK4, CRAF and BRAF have been previously shown to interact.
The experimentation is limited to the cryoEM analysis, and is lacking additional studies that would give deeper insight into the oligomeric nature - if any - of the GC-C when bound to HSP90-CDC37 as compared to the free protein. This is relevant, as the dimerization domain downstream of the pseudokinase, is evident in the maps - albeit not well resolved - and it is not clear whether it is still able to mediate dimerization with a second free or HSP90-CDC37-bound GC-C. It would also be good to see some experimentation that asks whether association with HSP90-CDC37 inhibits the guanyl cyclase activity. It is clear from previous work that HSP90-CDC37 silence the kinase activity of their bound client kinases, but in this case the catalytic guanyl cyclase is not directly associated with the chaperone complex and may still be able to function.
Although the sequence alignment presented in SuppFig 2 shows that GC-C conserves the classic DFG motif that plays a critical role in the regulation of most kinases, the numbering of the sequence is absent, making it very difficult to relate this to the structural detail shown in Fig 2B. This needs to be clarified, as the interaction of CDC37-Trp31 with the DFG motifs and downstream activation loops in CRAF and BRAF have been proposed as important features of the selectivity of these kinases for the HSP90-CDC37 system, and it would be good to be able to see clearly how much of this is also conserved in the GC-C pseudokinase domain interaction. For example, is the much shorter activation segment (DFG -> APE) ordered in the complex or disordered?
It was not easy to follow what was in the sample used for cryoEM. The cloning of the guanylyl cyclase (GC) component is described in the methods and they have shown some illustrations in fig 1 but a proper numbered figure of the domain organisation clearly showing domain boundaries and linker segments is really needed for a reader not familiar with the structure of GCs, especially since they have replaced the ECD with a leucine zipper in their construct. It is important to show a domain figure of what this construct looks like as well, as from the illustrations in fig 1 for examples its hard to see what's PK, DD, GC domains. It would also be helpful to see in the supplementary a gel of complex they put on the grids, to make it clearer what exactly the sample is and to reassure that the GC-C domains that are not resolved in the cryoEM are nonetheless present in the sample.
Overall there is only minimal proposal of mechanism or biological function based on the structure. The speculation in the Discussion of two fates - PP5 dephosphorylation or E3 ligase recruitment, is not supported by any experimentation, which is reasonable for speculation, but is also not underpinned by reference to any previously published work suggesting that these additional processes may be important. In the absence of any work by the authors can they put these speculations more in context with previously published work that supports the importance of these processes specifically for GC regulation?
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The study focuses on a mechanism of pest/pathogen resistance identified in Solanum commersonii, which appears to offer dominant resistance to Alternaria solani through the activity of specific glycosyltransferases which facilitate the production of tetraose glycoalkaloids in leaf tissue. The authors demonstrated that these glycoalkaloids are suppressive to the growth of multiple pathogenic ascomycetes and furthermore, that transgenic plants expressing these glycosyltransferases in susceptibleS. commersonii clones demonstrate improved resistance to a specific strain of A. solani and a genotype of Colorado Potato Beetle. The study design is straightforward, yet thorough, and does a good job demonstrating the importance of these genes in resistance. While the research findings are significant there are statements throughout the manuscript that overstate both the novelty and utility of the findings.
Title: While the protection is impressive, the title suggests that these glycoalkaloids provide protection against all fungi and insects, which is both unlikely and essentially impossible to prove. This should be changed to something more measured. This is especially true given that only a single fungus and insect were tested against transgenic plants, but would be an overstatement even with more robust evaluation.
Throughout the paper: A single isolate of A. solani and a single genotype of CPB were used in this study. While this is in line with the typical limitations of such a study, the authors need to be careful about claiming broad resistance to either of the species. Variability in fungicide tolerance and detoxification activity have been noted in both fungi and CPB, so more specific language should be used throughout (such as L213 and L221).
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Cacioppo et al describe a mechanism of translation regulation of Aurora A, which is dependent on alternative polyadenylation. They suggest that altered expression of the resulting isoforms in cancers is at least partly responsible for elevated Aurora A levels, which in turn is known to indicate poor prognosis.
The authors exploit publicly available databases and patient data to highlight the correlation of increased abundance of the SHORT isoform (relative to the LONG one) and poor patient survival in TNBC, as well as breast and lung cancer.
In their thorough mechanistic study they use a number of reporters to assess the impact of alternative polyadenylation on mRNA stability and translation efficiency and explore whether this process accounts for cell-cycle-regulated expression of Aurora A. These reporters are carefully controlled and well explained. I particularly commend the authors for the clear graphical presentations of the reporters (eg fig 2A, fig 3D, fig 4A). Rigorous control experiments are performed to make sure that the reporters work and "report" what they are meant to do, and to show that previous findings can be reproduced in experiments based on the reporters (eg higher protein expression from the short 3' UTR APA isoform of CDC6 mRNA, targeting of MZF1 3'UTR by hsa-let-7a).
They show that translation of the longer isoform is subject to suppression by hsa-let-7a, while the shorter isoform is not. They attribute cell-cycle regulated expression of Aurora A at least in part to the suppression of translation of the LONG isoform in G1 and S.<br /> In Figure 6 they address whether the APA-based regulatory mechanism alters Aurora A levels sufficiently to confer features associated with oncogenic transformation and overexpression of Aurora A. These data nicely tie together the observations in databases and the mechanistic part of the study.
The logic is clear and the conclusions are well supported by the data.
The authors state themselves that the impact of translation regulation on Aurora A levels in the cell cycle is an important but unanswered question. The evidence that suppression of translation of the LONG transcript contributes to the cell-cycle regulation of Aurora A is convincing, but the extent could be explored further. I wonder whether published genome-wide studies (eg PMCID 4548207, PMC3959127) have relevant data on the translation rate of Aurora A in the cell cycle.
In the paper this question is addressed in cells enriched in G1/S (Fig 6) and using the reporters (Fig 5). Having generated the ΔdPAS mutants, Aurora A levels could be easily assessed in each cell-cycle phase. The best way to do this would be sorting followed by immunoblotting.
The fact that Aurora A levels are reduced by a 6h treatment with 0.1 mg/ml CHX (Fig 6D) is interpreted as "AURKA expression in G1/S was reduced in the mutated cell lines when treated with CHX, indicating that translation of the short isoform is active in this phase" It is rather expected that using a translation inhibitor will stop the accumulation of a protein and so this experiment does not add much. A better approach to address the effect of the mutations on translation would be to add a proteasome inhibitor and follow accumulation of Aurora A, preferably not only in G1/S but also in other cell-cycle phases. Accumulation of the protein in this experiment would better reflect translation rates.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Preserving and restoring the fertility of prepubertal patients undergoing gonadotoxic treatments involves freezing testicular fragments and waking them up in a culture in the context of medically assisted procreation. This implies that spermatogenesis must be fully reproduced ex vivo. The parameters of this type of culture must be validated using non-human models. In this article, the authors make an extensive study of the quality of the organotypic culture of neonatal mouse testes, paying particular attention to the differentiation and endocrine function of Leydig cells. They show that fetal Leydig cells present at the start of culture fail to complete the differentiation process into adult Leydig cells, which has an impact on the nature of the steroids produced and even on the signaling of these hormones.
The authors make an extensive study of the different populations of Leydig cells which are supposed to succeed each other during the first month of life of the mouse to end up with a population of adult and fully functional cells. The authors combine quantitative in situ studies with more global analyzes (RT-QtPCR Western blot, hormonal assays), which range from gene to hormone. This study is well written and illustrated, the description of the methods is honest, the analyses systematic, and are accompanied by multiple relevant control conditions.
Since the aim of the study was to study Leydig cell differentiation in neonatal mouse testis cultures, the study is well conceived, the results answer the initial question and are not over-interpreted.
My main concern is to understand why the authors have undertaken so much work when they mention RNA extractions and western blot, that the necrotic central part had to be carefully removed. There is no information on how this parameter was considered for immunohistochemistry and steroid measurements. The authors describe the initial material as a quarter testis, but they don't mention the resulting size of the fragment. A brief review of the literature shows that if often the culture medium is crucial for the quality of the culture (and in particular the supplementations as discussed by the authors here), the size of the fragments is also a determining factor, especially for long cultures. The main limitation of the study is therefore that the authors cannot exclude that central necrosis can have harmful effects on the survival and/or the growth and/or the differentiation of the testis in culture. In this sense, the general interpretation that the authors make of their work is correct, the culture conditions are not optimized.
Organotypic culture is currently trying to cross the doors of academic research laboratories to become a clinical tool, but it requires many adjustments and many quality controls. This study shows a perfect example of the pitfall often associated with this approach. The road is still long, but every piece of information is useful.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript is an impressive "resurrection" of physiology regarding an enigmatic though unfortunately extinct species, and their potential adaptation to cold-water environments. I am largely convinced of their findings, which I feel are very straightforward and thorough.
One place where the authors perhaps fell a bit short was regarding some conclusions associated with maternal/fetal oxygen delivery. The sirenian versions of fetal & embryonic hemoglobin genes have been identified and assessed to some degree in previously published work the same research group. I feel the manuscript would have benefited from actual analysis of the fetal & embryonic hemoglobin (epsilon, gamma, zeta) to strengthen their assertions.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Parasitic African trypanosomes are agents of devastating diseases in humans and animals. Currently, no vaccines exist, with control of human disease being realized thru vector suppression and elimination of infected hosts while animal diseases remain rampant on the continent. The molecular aspects of the multiple developmental stages the parasite undergoes thru its mammal and tsetse hosts, and the unique aspects of parasite gene expression regulation and host evasion mechanisms have been extensively investigated. Recent applications of single-cell transcriptomics (scRNA) to these approaches have expanded knowledge gained from total RNA and revealed new insights.
In this paper, Briggs et al., set out to determine the cell cycle-related genes (CCR) of T. brucei, which follows the typical eukaryotic progression through G1, S, G2, and M phases followed by cytokinesis, although trypanosomes are unusual in that both nuclear and mitochondrial genome replication and segregation are orchestrated during cell division. while many regulators remain unidentified, are absent, or have been replaced by trypanosomatid-specific factors. For these studies, they apply scRNA methodology using asynchronous mixed populations of cultured 'monomorphic' slender mammalian (BSF) and insect stage (PCF) cells and then determine their cell cycle phases computationally. Of interest, performing similar analysis with fresh and cryopreserved cells made minimal difference to the outcome, thus enabling future investigations with preserved cells.
The study identified 1,550 genes with dynamic transcript level changes reflective of the cell cycle, 1,151 of which had not been previously identified by bulk analysis. These revealed a common set of highly conserved CCR genes as well as unique gene transcript levels expressed thru the cell cycle for BSF and PCF cells. Expression patterns of the G1 and S phase genes are highly comparable between BSF and PCF forms, whereas, after the S phase, the timing of gene expression for the S-G2 transition is far less synchronized. Comparison between transcript expression patterns and previously published protein abundance changes identified a relative delay in peak levels for transcript and protein for at least 50% of the genes that could be compared. Collectively, this foundational analysis generates transcript atlases for BSF and PCF cell cycles, which can be further mined for downstream functional investigations.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Nurr1 is a nuclear receptor and is important for mammalian brain development and homeostasis. Dysfunctional Nurr1 transcriptional activities are implicated in neurodegenerative diseases like Parkinson's. This exquisite ligand-dependent and specific transcriptional reprogramming make nuclear receptors ideal drug targets. However, the design of Nurr1-selective ligands has been confounded by the fact that Nurr1's ligand binding pocket appears to collapse in x-ray crystal structures. Interestingly, RXRalpha-targeted ligands, Nurr1's obligate heterodimer binding partner, show differential effects on Nurr1's transcriptional activities. In this study, the authors aimed to address how RXRalpha ligands lead to Nurr1 transcriptional activation. By combining biochemical approaches, NMR spectroscopy, and transcriptional reporter gene assays in neuronal cells, the authors convincingly show that these select RXRalpha ligands elicit an allosteric effect that reduces Nurr1 binding affinity. They further show that monomeric Nurr1 is a highly effective enhancer of the promoter that is repressed in the presence of RXRalpha. Overall, this is a well-presented and robust study as presented and the conclusions are supported by their evidence. This study should have a profound impact on the field as it provides a clear structural mechanism for ligand-dependent Nurr1 activation in neuronal cells.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors identified a novel TNFAIP3 variation Leu236Pro located in the A20 OUT domain and demonstrated its pathogenicity. Proinflammatory cytokines were substantially elevated in the patients. In vitro study showed decreased stability of the Leu236Pro A20 protein and Leu236Pro mutant failed to suppress TNF induced NF-κB activity. Review of previously reported TNFAIP3 missense variations revealed that only 3/7 are pathogenic. Truncating A20 mutations are easy to determine the pathogenicity, while missense TNFAIP3 variants require more functional studies to determine the pathogenicity. The results of this study can help interpretation of TNFAIP3 missense variations.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Sachiko et al. study presents strong evidence that implicates environmental volatile odorants, particularly diacetyl, in an alternate role as an inhibitors HDAC proteins and gene expression. HDACs are histone deacetylases that generally have repressive role in gene expression. In this paper the authors test the hypothesis that diacetyl, which is a compound emitted by rotting food sources, can diffuse through blood-brain-barrier and cell membranes to directly modulate HDAC activity to alter gene expression in a neural activity independent manner. This work is significant because the authors also link modulation of HDAC activity by diacetyl exposure to transcriptional and cellular responses to present it as a potential therapeutic agent for neurological diseases, such as inhibition of neuroblastoma and neurodegeneration.
The authors first demonstrate that exposure to diacetyl, and some other odorants, inhibits deacetylation activity of specific HDAC proteins using in vitro assays, and increases acetylation of specific histones in cultured cells. Consistent with a role for diacetyl in HDAC inhibition, the authors find dose dependent alterations in gene expression in different fly and mice tissues in response to diacetyl exposure. In flies they first identify a decrease in the expression of chemosensory receptors in olfactory neurons after exposure to diacetyl. Subsequently, they also observe large gene expression changes in the lungs, brain, and airways in mice. In flies, some of the gene expression changes in response to diacetyl are partially reversable and show an overlap with genes that alter expression in response to treatment with other HDAC inhibitors. Given the use of HDAC inhibitors as chemotherapy agents and treatment methods for cancers and neurodegenerative diseases, the authors hypothesize that diacetyl as an HDAC inhibitor can also serve similar functions. Indeed, they find that exposure of mice to diacetyl leads to a decrease in the brain expression of many genes normally upregulated in neuroblastomas, and selectively inhibited proliferation of cell lines which are driven from neuroblastomas. To test the potential for diacetyl in treatment of neurodegenerative diseases, the authors use the fly Huntington's disease model, utilizing the overexpression of Huntingtin protein with expanded poly-Q repeats in the photoreceptor rhabdomeres which leads to their degeneration. Exposing these flies to diacetyl significantly decreases the loss of rhabdomeres, suggesting a potential for diacetyl as a therapeutic agent for neurodegeneration.
The findings are very intriguing and highlight environmental chemicals as potent agents which can alter gene expression independent of their action through chemosensory receptors.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
Granell et al. investigated genetic factors underlying wheezing from birth to young adulthood using a robust data-driven approach with the aim of understanding the genetic architecture of different wheezing phenotypes. The association of 8.1 million single nucleotide polymorphisms (SNPs) with wheeze phenotypes derived from birth to 18 years of age was evaluated in 9,568 subjects from five independent cohorts from the United Kingdom. This meta-genome-wide association study (GWAS) revealed the suggestive association of 134 independent SNPs with at least one wheezing subtype. Among these, 85 genetic variants were found to be potentially causative. Indeed, some of these were located nearby well-known asthma loci (e.g., the 17q21 chromosome band), although ANXA1 was revealed for the first time to play an important role in early-onset persistent wheezing. This was strongly supported by functional evidence. One of the top ANXA1 SNPs associated with wheezing was found to be potentially involved in the regulation of the transcription of this gene due to its location at the promoter region. This polymorphism (rs75260654) had been previously evidenced to regulate the ANXA1 expression in immune cells, as well as in pulmonary cells through its association as an eQTL. Protein-protein network analyses revealed the interaction of ANXA1 with proteins involved in asthma pathophysiology and regulation of the inflammatory response. Additionally, the authors conducted a murine model, finding increased anxa1 levels after a challenge with house dust mite allergens. Mice deficient in anxa1 showed decreased lung function, increased eosinophilia, and Th2 cell levels after allergen stimulation. These results suggest the dysregulation of the immune response in the lungs, eosinophilia, and Th2-driven exacerbations in response to allergens as a result of decreased levels of anxa1. This coincides with evidence of lower plasmatic ANXA1 levels in patients with uncontrolled asthma, suggesting this locus is a very promising candidate as a target of novel therapeutic strategies.
Limitations of this piece of work that need to be acknowledged: (1) the manual and visual inspection of Locus Zoom plots for the refinement of association signals and identification of functional elements does not seem to be objective enough; (2) the sample size is limited, although the statistical power was improved by the assessment of very accurate disease sub-phenotype; (3) association signals with moderate significance levels but with strong functional evidence were found; (4) no direct replication of the findings in independent populations including diverse ancestry groups was described. Nonetheless, the robustness and consistency of the findings supported by different analytical and experimental layers is the major strength of this study.
The authors successfully achieved the aims of the study, strongly supported by the results presented. This study not only provides an exciting novel locus for wheezing with potential implications in the development of alternative therapeutic strategies but also opens the path for better-powered research of asthma genetics, focused on accurate disease phenotypes derived by innovative data-driven approaches that might speed up the process to disentangle the missing heritability of asthma, making use of still useful GWAS approaches.
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Reviewer #2 (Public Review):
This is an excellent study. It starts with the identification of two bactofilins in H. neptunium, a demonstration of their important role for the determination of cell shape and discovery of an associated endopeptidase to provide a convincing model for how these two classes of proteins interact to control cell shape. This model is backed up by a quantitative characterisation of their properties using high-resolution imaging and image analysis methods.
Overall, all evidence is very convincing and I do not have many recommendations on how to improve the manuscript.
In my opinion, there are only two issues that I have with the paper:
1. The single particle dynamics of BacA is presented as analysed and I would like to give some suggestions how to maybe extract even more information from the already acquired data:
1.1. Presentation: Figure 5A is only showing projections of single particle time-lapse movies. To convince the reader that it was indeed possible to detect single molecules it would be helpful if the authors present individual snapshots and intensity traces. In case of single molecules these will show step wise bleaching.
1.2. Analysis: Figure 5B and Supplement Figure 1 are showing the single particle tracking results, revealing that there are two populations of BacA-YFP in the cell. However, this data does not show if individual BacA particles transition between these two populations or not. A more detailed analysis of the existing data, where one can try to identify confinement events in single particle trajectories could be very revealing and help to understand the behaviour of BacA in more detail.
2. The title of Fig. 3 says that BacA and BacD copolymerise, however, the data presented to confirm this conclusion is actually rather weak. First, the Alphafold prediction does not show the co-polymer, and second, the in vitro polymerisation experiments were only done with BacA in the absence of BacD. Accordingly, the only evidence that supports this is their colocalization in fluorescence microscopy. I suggest either weakening the statement or changing the title adds more evidence.
Finally, did the authors think about biochemical experiments to study the interaction between the cytoplasmic part of LmdC and the bactofilins? These could further support their model.
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Reviewer #2 (Public Review):
This work sheds new light on the growth trajectory of Bonobo and contributes heavily to the discussion of the exclusivity of certain aspects of growth in modern humans. These results are also interesting as long as they are based on the study of the largest sample ever considered in the study of the growth of this species by including morphometric measurements as well as endocrinological factors.
The authors approach the study of the presence of growth spurs (GS) in Bonobo on the basis that GS are exclusive to the growth in modern humans. This idea is fairly widespread, however studies on non-human primates have shown an acceleration of growth during adolescence in several species, these works are recalled, presented and discussed by the authors. The originality of this work lies in highlighting the importance of scaling in studies of growth trajectories. The absence of GS in Bonobo but also in other primate species may result from not considering the conjunction of weight and height in the analysis of growth, because the pronounced changes in the speed of the height are in relation to the speed of changes in weight and this is modified according to the size/age. The authors apply scaling corrections to their results and the GS become evident (or more obvious) in Bonobo. Thus, the exclusivity of GS in growth in modern humans may in fact result only by the application of analytical approach not very appropriate in non-human primates.
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Reviewer #2 (Public Review):
In this manuscript, Castanera et al. investigated how transposable elements (TEs) altered gene expression in rice and how these changes were selected during the domestication of rice. Using GWAS, the authors found many TE polymorphisms in the proximity of genes to be correlated to distinct gene expression patterns between O. sativa ssp. japonica and O. sativa ssp. indica and between two different growing conditions (wet and drought). Thereby, the authors found some evidence of positive selection on some TE polymorphisms that could have contributed to the evolution of the different rice subspecies. These findings are underlined by some examples, which illustrate how changes in the expression of some specific genes could have been advantageous under different conditions. In this work, the authors manage to show that TEs should not be ignored when investigating the domestication of rise as they could have played an important role in contributing to the genetic diversity that was selected. However, this study stops short of identifying causations as the used method, GWAS, can only identify promising correlations. Nevertheless, this study contributes interesting insights into the role TEs played during the evolution of rice and will be of interest to a broader audience interested in the role TEs played during the evolution of plants in general.
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Reviewer #2 (Public Review):
This paper extends prior work demonstrating the importance of K145 acetylation of TDP-43 as a post-translational modification that impacts its RNA-binding capacity and may contribute to pathology in FTLD-ALS. The main strengths of this paper are the generation of a novel mouse model, using CRISPR gene editing, in which an acetylation-mimetic mutation (K to Q) is introduced at position 145. Behavioral, biochemical, and genetic analyses indicate that these mice display phenotypes relevant to TDP-43-associated disease and will be a valuable contribution to the field. While most of the data are rigorous and clearly presented, several weaknesses should be addressed to strengthen the manuscript and further characterize the phenotype of mutant mice.
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Reviewer #2 (Public Review):
This study reports a novel role of the natriuretic receptors Npr3 and Npr1 in the formation of neural crest (NC) and cranial placode (CP) progenitor populations in frog embryos. The authors discovered this receptor family in a screen for genes activated during NC development. They show the relevant expression of these receptors and the corresponding ligands in the NC and CP populations. Knockdown and rescue experiments combined with pharmacological drug treatment demonstrated that Npr3 clearance activity is required for NC progenitor formation. Surprisingly, adenylyl cyclase inhibition was required for cGMP production and the effect on CP development. The authors conclude that the two second messengers downstream participate in the segregation of the NC and CP progenitors in embryonic development.
The significance of this study is in the demonstration of two distinct developmental programs that are separately controlled by different activities of the same receptor. The study is well designed and executed with proper controls. Nevertheless, the data suggesting that Npr3 regulates NC and CP fates via different mechanisms are limited and need further support, such as the analysis of additional markers for CP progenitors, to be unambiguously interpreted. The work is likely to impact two different areas: early embryonic development and natriuretic peptide signaling.
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Reviewer #2 (Public Review):
Rapan and colleagues did perform an impressive multi-modal parcellation of the macaque frontal cortex. In addition to qualitative cytoarchitectonic and resting-state functional fMRI data analyses, the authors based their parcellation on quantitative receptor density analysis of 14 receptors. Compared with the classic Walker map of the macaque frontal cortex, the authors produced a more refined map. Those results should be discussed in light of previous work on the same topic (Petrides et al. 2012 Cortex; Reveley et al. 2017 Cerebral Cortex; Saleem and Logothetis 2012).
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Reviewer #2 (Public Review):
Immature lattice assembly remains an arcane topic, and these simulations provide high resolution data such as assembly kinetics and large-scale lattice rearrangement. Further, the authors extend their model to compare directly with experiments, e.g. SNAP-HALO dimerization, which provides a basis to interpret their conclusions. The manuscript is difficult to read, as it is a technical manuscript that overuses jargon; overall, it seems written for a specialized audience. Additionally, there are several aspects of the model design that remain opaque, such as the implicit lipid method and the suppression of multi-site nucleation. Further, analyses such as time auto-correlation and mean first passage time are not given much context by the authors. Altogether, it is the opinion of this reviewer that several revisions to the manuscript should be incorporated to improve clarity and strengthen the significance of the authors' efforts.
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Reviewer #2 (Public Review):
This study by Yamaguchi and Peltier provides a detailed investigation of the brainstem CPG functional organization that rules vocal behaviors in several Xenopus species, from an evolutionary perspective. The main conclusion of the paper reveals that vocal CPGs, located in the brainstem, generating fast and slow clicks in Xenopus male courtship calls are conserved across various Xenopus species. But the development of the fast CPG depends on testosterone only in species producing fast-click courtship calls.
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Reviewer #2 (Public Review):
ATM and Rad3-related (ATR) interact with ATRIP and plays a central role in DNA damage response. Previous studies have established the idea that ATR is recruited to RPA-covered ssDNA via ATRIP-RPA interaction. In this paper, the authors propose a new RPA-independent mechanism for ATR recruitment.
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Reviewer #2 (Public Review):
The authors used single cell transcriptome analysis of zebrafish skin cells and characterized various types of cells that are involved in scale formation and stripe patterning. The methods employed in this study is highly powerful to provide mechanistic explanation of these fundamental biological issues and will be a good example for many researchers studying other biological issues. Furthermore, the results characterizing differences in gene expression patterns among various types of cells will be informative for other researchers in the field.
For scale formation, it is known that mineralized tissues may significantly differ in rayfins and lobefins since sox9, col2a1, and col10a1 are all expressed in osteoblasts, in addition to chondrocytes, in zebrafish and gar (Eames et al., 2012, BMC Evol. Biol.). Furthermore, in mammals, Col10 is expressed in chondrocytes in mature cartilage that undergoes ossification. Thus, unlike the authors argue, col10a1 expression is not apparently relevant to the elasticity of scales.
The authors also state that the expression of dlx4a, msx2a, and runx2b characterize cells homologous to mammalian ameloblasts. However, dlx4, runx2, and msx2 are all duplicated in zebrafish, and the function of duplicated genes in teleost fishes may differ from that of single ancestral gene. Moreover, none of Dlx4, Msx2, and Runx2 is expressed specifically by ameloblasts in mammals. Indeed, both Msx2 and Runx2 are expressed in osteoblasts, while the expression of Dlx4 in ameloblasts is not reported. These results, together with the expression of an enamel gene, enam, in dermal cells (SFC), do not appear to support the homology of the surface tissue of mammalian teeth and zebrafish scales.
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Reviewer #2 (Public Review):
In a neonatal model of bacterial meningitis induced by s.c. injection of E. coli, transcriptional changes were found across all major cell types including endothelial cells, fibroblasts and macrophages. Among macrophages, they describe 2 resident subsets and 2 inflammatory subsets. By immunohistochemistry of arachnoid and dura flatmounts, they show vascular changes upon infection, including clustering of CLDN5 and PECAM1, and disorganized capillary morphology, which was dependent on Tlr4 signaling but independent of arachnoid macrophages.
The manuscript would benefit from rewriting, it is not written in a concise manner and the rationale for experiments, time points for analyses and their conclusions are not clear. The model of s.c. bacterial infection is not well introduced and overall changes in the periphery, survival curves or bacterial counts (in the KO models) in the meninges/brain are not mentioned.
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Reviewer #2 (Public Review):
This study aimed to classify colorectal cancer (CRC) samples based on the expression of genes in selected gene lists, where the gene lists were chosen to represent aspects of the tumour microenvironment, tumour-associated immune cells, and tumour cells. The resulting clusters were then used to define a classifier, followed by a detailed description of molecular features of the tumours and tumour microenvironments assigned to each cluster. The authors claim this study is more "holistic" than previous work on CRC clustering/classifiers because they aimed to explicitly include additional components of the tumour microenvironment in both the clustering/classifier definition and in the subsequent description of molecular characteristics.
The CCCRC clustering and the resulting classifier presented in this paper are derived from published RNAseq studies. The multi-omics aspect of the work is restricted to smaller sample numbers for which both transcriptomic and another omics dataset were available in public resources and comprises a description or correlative analysis of each omics data type within each of the assigned CCCRC subtypes.
By applying solid computational methods to a compendium of published RNAseq datasets (n~1500 tumours), they found that tumour samples from colorectal cancers clustered into 4 subtypes ("CCCRC" subtypes) on the basis of 61 pre-defined gene expression signatures. These subtypes correlated with but did not correspond to, the previously described Consensus Molecular Subtypes (CMS) of colorectal tumours.
Other types of molecular data were available for some tumours, obtained from the same published resources: whole-slide images, mutations, tumour proteomics, and/or scRNAseq. The authors reanalysed these datasets using standard methods and drew correlations with the CCCRC subtypes they had assigned in this work. To (semi-)quantify immune infiltration characteristics from whole-slide images (WSI), they additionally performed automated segmentation in addition to review by pathologists, which in combination produced a convincing WSI-derived dataset.
In combination with existing CRC classifications, this study could facilitate future biomarker discoveries. This appears to be the authors' main claim, and the data and methods broadly support this claim.
Some aspects of the work need to be clarified:
This work relies on the definition of 4 clusters of CRC tumours based on consensus clustering of the 61 gene lists, which in turn depends on the choice of clustering method and the choice of gene lists. Sufficient detail is provided about the gene lists and resulting clusters, but this paper does not show how robust the 4 clusters are to these choices; for example, the "Energy" gene list appears to be a relatively strong component of clusters C2 and C3.
The authors examined whether their CCCRC classification showed differential disease progression in available retrospective cohorts of people treated with anti-PDL1 therapy. The authors presented this work as "significance of CCCRC in guiding the clinical treatment of colorectal cancer", but the data presented in this section cannot support clinical treatment decisions, which would require prospective studies and clinical trial designs. However, this section is potentially useful for generating hypotheses about potential biomarkers related to the CCCRC subtypes, and might, in the future with additional evidence, contribute to the design of a trial. The authors point out that additional experimental evidence would be required.
Other prognostic or predictive clinicopathological variables for colorectal cancer are not discussed in detail in the present work but are important for further work on the prognostic and predictive value of CRC molecular subtypes and biomarker derivation. Discrepancies in treatment response have previously been observed in separate CRC trials of biologically targeted agents with different chemotherapy backbones and other authors have suggested that treatment interactions with the tumour microenvironment might in part explain these discrepancies (e.g. Aderka (2019) PMID:31044725, and others).
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Reviewer #2 (Public Review):
This paper provides an important and insightful investigation into patterns of activations that emerge in external task states. The authors use state-of-the-art methods and novel analytic approaches to establish that deactivations in the default mode network during external tasks are driven by activity in brain regions that are important in the current tasks (such as the visual or dorsal attention networks). It will be important in the future to understand whether this is a symmetrical phenomenon by studying this behaviour in states that maximize activity within the default mode network and also drive reductions in networks that are not relevant to these situations.
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Reviewer #2 (Public Review):
Since this study is a long-term cohort study in children and adolescents, it is advisable to decide whether to highlight differences by age group or to show consistent effect after exposure. In particular, obesity and related diseases are closely related to socio-economic environmental factors, and its impact might be different according to age (group) at exposure.
The part described in comparison with previous studies is a good attempt. However, some results are consistent with those of previous studies and some are not. This may be related to the time difference in socio-economic environmental factors rather than simply the difference between the West and China (Hong Kong). According to modernization/urbanization, changes in living environment, changes in family relationships, and changes in the care environment can also be factors especially in children.
In studying the effect of environment on gene expression, it can be thought that the influence of genes and the degree of expression might be different depending on the age of the subject (newborn, infant, infant, adolescent, adult) duration of exposure and these still need to be elucidated.
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Reviewer #2 (Public Review):
In the manuscript, Chen and colleagues reconstituted the minimal system that indicates the coupling of PSD condensates with actin polymerization. While the functional connection between the assembly and dynamics of PSD and actin was known, the molecular mechanism remained elusive. Using a series of elegant biochemical reconstitutions and in-vitro assays complemented with analysis in living cells and primary neurons, the authors characterized whether PSD condensates of Homer-1, Shank-3 and SAPAP/GKAP are sufficient to induce F-actin bundling. Furthermore, they dissected the positively-charged Arg patch within EVH1 domain of Homer to be crucial for the F-actin bundling. Postsynaptic CaMKII and a short isoform of Homer, Homer1a, can both attenuate this process, suggesting various mechanisms neurons can regulate this process. Overall, the topic is timely, the study is well-designed, and the assays are clearly executed. However, several aspects need to be experimentally addressed, including some important controls:
1. It is well established that molecular crowding plays a crucial role in F-actin bundling. For example, in the reconstitution assays in Fig.1, the authors use 10 µM of each component of PSD (total of 60 µM), to which 5 µM actin is added. Yet, in their control assays (Supp. Fig. 1), only 10 µM of each protein was checked with the same amount of actin. A control is missing where the total protein crowding would be preserved, for example, by adding BSA or protein to mimic non-specific protein crowding.<br /> 2. Is the F-bunding observed under these physiological ratios of PSD proteins and actin? For instance, a recent quantitative study (PMID: 34168338) suggests actin:Homer-1 is 200:1 or 100:1, which is in stark difference from the 1:2 molar ratio used in the study. The protein concentrations (molar ratios) need to match the physiological.<br /> 3. In the cell migration assays, it is somewhat unclear to what extent the interaction is direct. For instance, co-sedimentation at ultra-speed (100,000 g) was used to suggest a direct binding of EVH1-GNC4 fusions (Homer1, Enah) with F-actin. The control that needs to be included is a protein known not to bind to F-actin incubated under the same conditions (salt concentration, duration of incubation) and spun down at 100,000xg. This is important to exclude that the tested proteins non-specifically entangle into F-actin without specifically binding to it, particularly at such high speed.<br /> 4. The imaging assay in hippocampal neurons uses an increased spine head size as a proxy for F-actin bundling. However, one needs to be careful as the baseline includes soluble mCherry, which is both much smaller in size and does not specifically enrich the spines. The image of Homer 1 R3E shows overall lower localization at the spines. Thus, one cannot exclude that the spine enlargement upon overexpression of Homer 1 wt and R3E+EN is not primarily driven by their overall enrichment in the PSD phase. A suitable control for this assay would be mCherry-tagged PSD95, which would localize to the spines yet is not directly involved in F-actin bundling.
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Reviewer #2 (Public Review):
This work is a cross-validation of an x-ray tomography technique (SAXS) and an optical microscopy technique (SLI) for imaging axonal orientations ex vivo. These innovative methods were introduced in recent papers by the authors, who have teamed up here to compare them side-by-side on the same tissue samples for the first time. The two methods are both label-free (do not require staining) and they are quite complementary. SAXS can provide full 3D orientation measurements on intact tissue, but it operates at a mesoscopic resolution and requires access to a synchrotron. SLI can measure the orientations of multiple fascicles per voxel at a microscopic resolution and relies on more widely accessible equipment, but its accuracy suffers for fiber orientations perpendicular to the imaging plane and it requires tissue to be sectioned before it is imaged. Therefore it makes a lot of sense to explore the complementary strengths of these two techniques, and to use one to "fill in the blanks" of the other. The paper also compares the orientation measurements obtained with SAXS and SLI to those obtained with diffusion MRI. The latter provides only indirect measurements based on water diffusion, at a mesoscopic resolution somewhat lower than that of SAXS, but has the benefit of being feasible in vivo.
A limitation of this study is that conclusions on the comparison between SAXS and SLI are drawn from only 2 sections of a partial monkey brain sample and 2 sections of a partial human brain sample. Conclusions on diffusion MRI are drawn only on the 2 human sample sections. This is particularly an issue for the comparison to diffusion MRI, as the diffusion MRI voxels are wider than the section thickness, hence one cannot preclude that any orientations detected with diffusion MRI but not with SAXS and SLI come from the portion of the voxel that is missing from the corresponding SAXS/SLI section.
The stated aim of the paper is to provide a framework for combining the complementary benefits of SAXS and SLI, rather than simply presenting the results of a cross-validation study. This is a significant and ambitious aim. However, in order for this to serve as a framework, there would have to be clear prescriptions for how researchers interested in obtaining ground-truth measurements of axonal orientations would do so by using these two methods in tandem. This is not adequately developed in the paper in its present form. For example, the results show reasonable agreement between SAXS and SLI orientations when fibers lie within the SLI imaging plane and decreasing agreement for fibers with increasing through-plane inclination. How would the two methods be combined in voxels where they disagree? Would one use SLI orientations in voxels with fewer through-plane fibers and SAXS orientations in voxels with more through-plane fibers? How would voxels be assigned to each category? How would the orientation vectors from the two modalities be composed and how would the resolution difference between the two be handled? When the through-plane measurement of SLI is unreliable, is its in-plane measurement still reliable? That is if there were one mainly in-plane and one mainly through-plane fiber population, would the orientation of the former still be measured correctly by SLI? There is also considerable agreement reported here between through-plane orientations obtained with SAXS and diffusion MRI. Would this mean that diffusion MRI itself could be used to supplement SLI with through-plane orientations? Any clear set of prescriptions along these lines would represent a framework for imaging orientations by combining modalities. This, however, would require detailed steps for how to perform the combination and use the multi- vs. uni-modal framework to reconstruct connectional anatomy.
A key advantage of SAXS is that it can be performed on intact samples, i.e., before any nonlinear distortions of the tissue are introduced by sectioning. Thus it can provide an undistorted reference, with contrast on axonal orientations that would be absent in, say, a structural MRI of comparable resolution. This contrast could be used to drive registration of the distorted SLI sections to an undistorted SAXS volume, and therefore is a key way in which the two techniques can complement each other. Here, however, this is not explored, as SAXS is performed after sectioning. It is not clear if this is the authors' prescription for how a combined SAXS/SLI framework would be implemented, or if it was done specifically for this study. First, it would seem that SAXS on the intact sample would be lower maintenance, requiring less setup time and hence potentially less overall beamtime than performing SAXS on each section separately. This would make it more practical for routine deployment beyond a few sections. Second, because the SAXS data are now nonlinearly distorted, they cannot be affinely aligned to the MRI volumes. While, in principle, performing both SAXS and SLI on the sections may facilitate the comparison between the two, having to unmount, rehydrate, and remount the sections in between may negate this advantage, as now there is no guarantee that SAXS and SLI can be affinely registered to each other. Here all these registration steps are performed affinely, so it is unclear to which extent the computed errors between modalities are characterizing the inherent limitations of the respective contrasts, or limitations of the registration technique. Some of the alignment is performed manually, for example, specific regions of the images are realigned by hand, and the slice of the diffusion MRI volume that is aligned to the SAXS/SLI sections is chosen by hand. Again, for this to serve as a framework that can be deployed on whole samples, there would have to be clear prescriptions for how to perform these steps robustly, how to ensure that the MRI can be acquired in a coordinate frame parallel to the sections, etc.
Finally, the paper puts forth a general conclusion that diffusion MRI overestimates the number of fiber populations per voxel, on the basis of small ODF peaks appearing perpendicular to the main ODF peaks. Of all conclusions in the paper, this is the least convincingly supported by evidence. First, these small perpendicular peaks are a known artifact, which would be typically eliminated by ignoring ODF peaks below a certain amplitude, a common practice in diffusion tractography algorithms. The authors refrain from using an amplitude threshold, with the rationale that it may also remove true diffusion orientations. However, they apply a threshold when they detect SLI peaks (a rather stringent 8% of the maximum). Second, the explanation that these artifactual peaks may appear due to vessel walls is not convincing. Vasculature is sparse. A single vessel wall will not impact the diffusion signal in the same way as a bundle of parallel axons. In an axon bundle, water molecule displacements are restricted in all directions except parallel to the axons. A single vessel wall in a voxel will not have the same effect on displacements (which are much smaller than the size of the voxel). From Figure 5, it looks like there would be at most 1-2 of these vessels in a diffusion MRI voxel, and they would not be in all voxels. This cannot explain the widespread appearance of these small artifactual peaks. Third, many ODF reconstruction methods have parameters that can be adjusted to make these artifactual peaks more or less prominent. The default parameters may be optimal for in vivo but not ex vivo data, due to the effects of fixation. In light of these concerns, I would caution against making such a general statement about all diffusion MRI in the human brain, especially on the basis of a single diffusion reconstruction method applied to a single location in one brain.
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Reviewer #2 (Public Review):
Londoño-Nieto et al. investigated the influence of temperature on the form and intensity of sexual conflict in Drosophila melanogaster. They aimed to test the effect of naturally occurring temperature fluctuations on a wild population of Drosophila while disentangling pre- and post-copulatory episodes of sexual conflict. To this end, they exposed females to males under monogamy or polyandry, hence manipulating the degree of male harm experienced by females. The effect of temperature was explored by exposing these groups to 20, 24, or 28{degree sign}C. They found that female fitness suffered from male harm most at 24{degree sign}C and less at the other two temperatures. Interestingly, pre- and postcopulatory episodes of sexual conflict were affected differently by temperature. Overall, these data suggest that the relationship between sexual conflict and temperature can be strong and complex. Hence, these results can have important implications for the impact of sexual conflict on population viability, especially in light of the climate crisis.
This paper tackles a highly relevant question using an established model organism for sexual conflict and contains a rich dataset obtained using a series of carefully planned experiments and analysed in an appropriate way. Importantly, the authors used biologically meaningful temperatures and mating treatments, which increases the relevance of the data. The main conclusions are well supported by the data. Nevertheless, the devil is in the detail, and given the way the authors frame their study (i.e. testing a natural population under naturally occurring temperature fluctuations) and their results (i.e. sexual conflict is buffered by temperature effects in the wild) there are some limitations to be considered:
1) The authors frame their study as addressing the question of how sexual conflict reacts to naturally occurring temperature fluctuations in the wild. Nevertheless, the population used in this experiment had been kept for nearly 3 years in the laboratory prior to the experiment. Importantly, the authors ensured that the laboratory population maintained genetic diversity, by regularly crossing wild lines into it. Nevertheless, this population remained for some time in the laboratory under standardized conditions. The applied temperature fluctuations are in a biologically meaningful range (though only during the reproductive season), but it remains unclear if the applied fluctuations were in a standardized way (i.e. pre-programmed) or included random fluctuations (i.e. a more natural setting). This laboratory setup has certainly clear advantages, for example, it enables the exclusion of any effects other than the temperature on sexual conflict. Nevertheless, how these will then ultimately play out in the wild could be a different story.
2) The authors highlight clearly that temperature fluctuations in the wild might play an important part in how sexual conflict plays out in natural populations. This very interesting and highly relevant point might lead the reader to assume that this is what was actually tested in the experiment. Nevertheless, in the experiments, different constant temperatures were applied to the flies, while only the stock population was kept at a fluctuating temperature regime. Hence, the influence of fluctuations during episodes of sexual conflict remains untested. While the present data show that sexual conflict can be modulated by temperature, the effect of naturally occurring fluctuations on the net cost of sexual conflict to a population remains unclear.
3) The authors conclude that the effect of sexual conflict can be buffered by temperature in the wild. In general, I agree with this, although a more conservative way of framing this would be to say that temperature modulates or moderates sexual conflict instead of buffers it. If there really is a buffering effect of temperature in the wild remains to be tested, I believe. This will depend on how actual changes in temperature affect this dynamic (see point 2). In addition, I think another interesting open question is what the mechanism behind the observed differences might be. Are male and female interests really more aligned at different temperatures (i.e. males plastically reduce harm)? This would really buffer the harm of sexual conflict at those temperatures. Nevertheless, alternatively, males might not be perfectly adapted to manipulate the female optimally at lower or higher temperatures. This would mean that if the temperatures change, males might evolve to increase the manipulation of females, and hence the scope for sexual conflict might not change in the end under this scenario. Nevertheless, as the authors themselves state: 'An intriguing possibility is thus that SFPs are more effective at lowering female re-mating rates at warm temperatures, thereby buffering these costs.' Therefore, a temperature-dependent increase in the effectiveness of male manipulation might counterintuitively reduce sexual conflict in this species.
4) In the end the authors argue that the climate crisis might have 'unexpected positive consequences via its effect on male harm'. Sexual conflict is indeed widespread, but it takes many different forms (as has been nicely described in the introduction of this paper). Because the studied system seems to be quite a specific example, it is questionable how far spread this phenomenon is in nature. In addition, it remains unclear how male harm will evolve in response to the climate crisis (see point 3). Finally, the relative fitness of females increased in the present experiment, as the tested range was within the reproductive optimum of the species. Nevertheless, the relative importance of the positive effect of sexual conflict on fitness outside of optimal temperatures seems questionable.
Nonetheless, I believe these results to be of exceeding interest to the scientific community and of importance to the field. It opens up many potential research directions and adds further data to the fascinating field of sexual conflict, SFPs, and male harm in Drosophila.
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Reviewer #2 (Public Review):
The paper starts with the premise that given the broad immature connectivity between the retina and thalamus during development, locally homogeneous synaptic currents should generate precise spike correlations (on a millisecond timescale) which are not seen in development and could be bad for developmental refinements and "network diversity". Rather, the correlations during development are over much longer timescales. The authors propose that two main factors, the dominance of NMDA (over AMPA) currents and the absence of recurrent connections prevents these precise correlations and preserves diversity.
The paper consists of three parts: (I) develop a biophysical model for a thalamic neuron, (II) use the model to determine which factors govern precise correlations, and then (III) simulate a cortical network and demonstrate loss of network diversity when precise correlations are used. While all parts are interesting, there are several claims in each (and the links between them) that are not fully justified.
What is commending about the paper is that it is one of few theoretical/modeling papers that focuses on neural circuit development and it manages to link experimental results to principles of circuit function. The authors apply quite a few modeling approaches ranging from single-neuron models (including building a database of thalamic neurons based on experimental data) and network models. Some of the claims regarding the timescales of correlations (long in development) are unjustified because the authors use a fixed-timescales kernel to compute these correlations and mainly investigate their amplitude or level, not their timescales. It is also not clear how important is the heterogeneity among thalamic neurons. Are the effects on the correlations the result of NMDA currents or the neuronal diversity from their database? Are precise correlations generated because of the diverse/heterogeneous neurons, or because of the levels of convergence? What happens to homogeneous neurons? The authors also propose that precise correlations impair network diversity but never show this impairment directly beyond a diversity of excitatory-to-excitatory connection strengths. If the authors were to clarify these issues then the paper could be a valuable contribution to the field of developmental systems and computational neuroscience.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The overall objective of this paper is to characterize the cells that are responsible for producing the secretions of the parasitic larvae, Brugia malayi. This parasite is a human pathogen that is one of three responsible for lymphatic filariasis/elephantiasis a disease that threatens half of the world's population. The specific focus of this work is protein secretions made by the parasites. In general, it is well-known that parasitic worms can manipulate and evade host immune immunity via secreted products. Studies have focused on the activities of these secretions and specific molecules. What is lacking is a detailed description of the identity and anatomical location of the cells that produce them. This is especially important as these cells are the target of different classes of anthelminthic drugs. This knowledge could allow new strategies to target these pathogens and to better understand the mechanism of actions.
To better understand this important topic, this manuscript describes a method to dissociate cells of the pre-larval stage (microfilariae) of the human parasitic filarial nematode, Brugia malayi. This method is then used to create an atlas of cells based on the expression profiles of individual dissociated cells. Cells are grouped into clusters with similar patterns of expression using single-cell mRNA sequencing analysis pipelines and the clusters are defined by using a combination of known functionalities based on the well-established, free living, soil nematode, C. elegans, and different functional classifications based on genes of interest. These include known antigens as well as targets of 3 classes of anthelmintic molecules. Using the scRNA-seq data, clear hypotheses can be made about ion channel and structural protein composition, the putative targets of the anthelminthics. Finally, it is proposed that the dissociated cells can be cultured which can facilitate future studies since cell lines or primary cultures of cells from filarial worms are not available.
This paper represents a huge undertaking on an important and understudied area. The authors have taken on a major challenge to gain novel insights, and to provide data and protocols for the field to use. The data are well-presented and support the conclusions of the work. The authors have broadly achieved their goals and the data generated and methodology will be important for the community.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript is rigorous and clearly written; the experiments are well described, and the conclusions are consistent with the experimental results. Particularly interesting are the data demonstrating the role of cytoneme-like structures. The microscopy images supporting the experimental data are clear and fascinating.<br /> The work is, in my opinion, well conducted.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this manuscripts, the authors investigated differential role of two closely related proteins, S27 and S27L , which are one of the subunits of ribosome. Ribosomes containing each protein associate with a distinct set of mRNAs, suggesting that ribosomes in the cells play distinct roles depending on which subtype of S27 subunits they contain. The authors also performed functional analyses using mutant mice, and demonstrated that functions of S27-containing ribosome can be rescued by S27L-containing ribosome and vice versa. These findings provide new experimental insights into the origin of family genes fixed during the course of evolution.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this manuscript, the authors characterize the extent of RNA transfer between cells in culture, with an emphasis on trying to identify RNAs that are transferred through tunneling nanotubes (TNTs). They use an in vitro human-mouse cell co-culture model, consisting of mouse embryonic fibroblasts and human MCF7 breast cancer cells. They take advantage of the CD326 cell surface molecule, which is specifically expressed on MCF7 cells, to separate the two cell populations using magnetic beads conjugated to anti-CD326 antibodies, followed by deep sequencing to identify human RNAs present in mouse cells. They identify many 'transferred' RNAs. Further analysis of sequencing data together with experiments using synthetic reporters indicate that RNA transfer is non-selective, that the amount of transfer strongly correlates with the level of expression in donor cells, and does not appear to require specific RNA motifs. The authors also note that co-culture with MCF7 cells leads to significant changes in the MEF transcriptome.
The experiments are overall carefully designed, and the data are clearly and quite carefully presented to point out limitations in interpretation and to distinguish speculations from experimental conclusions. It should however be kept in mind that it is unclear to what extent these limitations influence the conclusions reached. For example, the identification of transferred RNAs relies on the purity of the isolated cell populations and, while the authors provide some supporting evidence for this, nevertheless potential caveats remain. For instance, the isolated MEF samples used for analysis appear to lack single MCF7 cells, but still contain components, labeled as 'double stained' and 'unstained' cells, which are uncharacterized. The authors present some arguments as to why these would not contribute to 'transferred' reads, but given the low level of detectable transferred RNAs, and the unclear origin of these components, whether they influence the results could be debatable. Furthermore, the small number of replicates (2 replicates for the genome-wide studies and 1 replicate for most of the subsequent experiments) minimizes the confidence in the conclusions. In this context, it is also notable that the profile of transferred RNAs between the two replicates of co-cultured samples appears quite different by PCA analysis. It is thus conceivable that there might be specificity in the RNA 'transferome', influenced by unknown experimental variables, which is though masked when averaging those samples in subsequent analyses.
While the manuscript emphasizes the role of TNTs in RNA transfer, the actual involvement of TNTs relies solely on the observation that potential TNTs form between co-cultured cells. Other means of transfer, such as through engulfment or phagocytosis of cell fragments, could still possibly contribute. Furthermore, the dependence of mRNA transfer on direct cell-to-cell contact is demonstrated for 5 RNAs and extrapolated to transcriptome-wide RNA transfer, an assumption which might, or might not, be valid.
Finally, the results on gene expression changes induced by co-culture (Figures 7, 8) are of unclear relevance. As the authors point out, it is uncertain whether RNA transfer or other paracrine or adhesion-mediated signaling events, underlie these changes. It is therefore not easy to see how these results relate to the rest of the presented work. Furthermore, while the authors expand on the potential significance of changes observed in genes related to cancer-associated fibroblasts or to immunity-related genes, these remain speculative and untested.
Overall, the manuscript presents evidence indicating that RNA is transferred non-selectively in co-cultured cells, under specific conditions and between the cell types tested. The impact of the work is reduced by the lack of mechanistic understanding underlying this transfer and the uncertainty of whether this phenomenon has any subsequent physiological relevance.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript by Laturney et al. has found a previously uncharacterized neural link between female mating status and upregulation of sugar intake in the common fruit fly, Drosophila melanogaster. Although mated female flies have been known to increase both yeast and salt intake compared to virgin females, changes in sugar intake have not been previously described. Using quantitative monitoring of food intake, functional calcium imaging, connectome tracing, and neuronal manipulations, authors convincingly demonstrated that the Sex Peptide sensory neurons (SPSN) and their downstream neural circuit control the activity of female-specific Lgr3 neurons in a mating-dependent manner. In virgin females, the SPSN circuit (including its output pCd-2 neurons) is active, which is predicted to inhibit hunger-promoting Lgr3 neurons. After mating, the SPSN circuit becomes silent, which should disinhibit Lgr3 neurons. Indeed, they found that optogenetic silencing of pC2-d neurons promoted sucrose consumption. The newly characterized pCd-2 neurons are sexually dimorphic, consistent with their role in female-specific post-mating modulation of sucrose consumption.
Aside from the novelty of the mating-dependent changes in sugar intake, an exciting discovery of the current study is that separate circuits control different aspects of post-mating behavioral changes (increased egg-laying, mating rejection, increased sugar consumption). This finding illustrates a general neural mechanism by which a single "internal state" exerts its influences on multiple behaviors via branches of circuits from a hub for the given state (pC1 for the female mating status), which is a powerful mechanistic model for other internal states.
The high-quality data based on elegant yet rigorous experiments deserve praise as a textbook example. They presented multiple independent lines of evidence to demonstrate the function of each component of the SPSN circuit over the sucrose consumption Lgr3 neurons, which convincingly proves that the pCd-2a/b neurons transmit information of mating status to a hunger-controlling hub. Experiments have been exceptionally rigorous. Genetic manipulations were performed with multiple controls. They used multiple split GAL4 lines to target specific classes of neurons to eliminate the neuronal off-target effect. They also used multiple types of feeding assays to clarify the feeding phenotype induced by mating. Overall, the scientific rigor of this work sets a standard for researchers in the field to follow.
That the activity levels of pCd-2 neurons and their downstream Lgr3 neurons are indeed influenced by mating has not been directly tested. Since multiple previous publications consistently demonstrated that the SPSN-SAG-pC1 axis is suppressed by the Sex Peptide, the authors' conclusion that pCd-2 neurons are suppressed after mating (for example, see line 319) is very likely correct. However, what the authors showed was that silencing of the SPSN circuit "can" increase sucrose consumption in virgin females. To what extent mating suppresses pCd-2 neurons (and disinhibits Lgr3 neurons) remains uncharacterized. The inhibition exerted by the Sex Peptide is likely partial, which might not be precisely recapitulated by the optogenetic silencing. Mated female flies show an increased preference for protein and salt. The authors' finding that they also increase sugar consumption after mating indicates that mating causes a substantial change in female feeding patterns. The current work elevates the value of Drosophila as a neurogenetic model to understand how the nervous system achieves the complex tasks of nutritional homeostasis after mating, which dramatically alters the energy allocation in many species (including mammals). Data presented in this work will advance our understanding of how females coordinate feeding priorities in a face of changing nutritional demands after mating, which is one of the fundamental questions in neuroscience.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The large genetic association studies conducted in East Africa have shown that the Dantu blood group provides substantial protection against severe malaria. The proposed mechanism of protection is reduced red cell invasion resulting in reduced parasite multiplication. This hypothesis was tested in adult Kenyan volunteers infected with P. falciparum under careful monitoring. The strength of the study is that the CHMI model using a single parasite strain has few confounders and it provides a very clear answer. The data reported on the other "protective" genetic polymorphisms is also fascinating. The hypothesis that Dantu reduces merozoite invasion has some support from previous laboratory studies, but it would be useful to confirm, once invasion is successful, that intraerythrocytic growth is unimpaired (e.g. count merozoites per schizont, measure asexual cycle length etc).
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this manuscript, Seelbinder et al, introduce a novel, elegant approach to study the organization of cell nuclei, which complements currently existing technology. The authors employ localized temperature gradients to move chromatin inside the nucleus noninvasively, and they study flow fields and deformations of different nuclear compartments in different experimental settings. The study is timely and should be of broad interest to a wide readership, in particular since the method can also be applied to study mechanical relationships of subcellular compartments in other cellular and extracellular systems.
The non-invasive manipulation of cell organelles in intact cells has been a challenge for decades. The new technique introduced in this study contributes to closing this important gap, enabling experiments to better understand spatial and mechanical relationships between different cell compartments. This study is a very nice example of how concepts and approaches from physics can be exploited to better understand biology.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Ramesh, Liu et al. investigated the dynamics of the histone H3 lysine 27 trimethyl mark (H3K27me3) in the cerebellum during postnatal development. They profile the mark and measure gene expression at three time points (P7, P14, P60) to show that there is a global increase in the amounts of H3K27me3 genome-wide, but a generalized loss of the mark at promoters. This loss is associated with neuronal genes that become expressed in the mature cerebellum. Through conditional knockout and transcription factor analysis, they implicate the autism-associated lysine demethylase gene KDM6B in the removal of H3K27me3 at genes that become active postnatally and show that the ZIC transcription factors are candidates to mediate some of these effects. They then use pharmacologic inhibition of KDM6B and the PRC2 component, EZH2, in a granule neuron culture system to further dissect the function of these enzymes in H3K27me3 dynamics.
The authors employ multiple genomic methods to carry out rigorously controlled experiments and their conclusions are well supported by the data. The study provides fundamental insights into the dynamics of H3K27me3 during the postnatal development of circuits in the brain. In particular, the findings that substantial changes in the H3K27me3 mark continue through the later steps of cerebellar maturation (P14 to P60) and that the autism-associated gene KDM6B is involved in this process, will be of significant interest to the field.
The study has some limitations with regard to scope and mechanism. For example, given the importance of enhancers in the regulation of gene expression, the omission of any analysis of H3K27me3 at defined enhancer elements is a limitation of the study. In addition, while the observations supporting the role of ZIC proteins in the removal of H3K27me3 during gene activation are interesting, the lack of direct mechanistic analysis investigating this biology limits the strength of the conclusions that can be made about the direct function of these factors in H3K27me3 dynamics.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this work Ushio et al. combine environmental DNA metabarcoding with novel statistical approaches to demonstrate how fish communities respond to changing sea temperatures over a seasonal cycle. These findings are important due to the need for new techniques that can better measure community stability under climate change. The eDNA metabarcoding dataset of 550 water samples over two years is, I feel, of sufficient scale to provide power to detect fine-scale ecological interactions, the experiments are well controlled, and the statistical analysis is thorough.
The major strengths of the manuscript are: (1) the magnitude of the dataset, which provides densely replicated sampling that can overcome some of the noise associated with eDNA metabarcoding data and scale up the number of data points to make unique inferences; (2) the novel method of transforming the metabarcode reads using endogenous qPCR "spike-in" data from a common reference species to obtain estimates of DNA concentration across other species; and (3) the statistical analysis of time-series and network data and translating it into interaction strengths between species provides a cross-disciplinary dimension to the work.
I feel like this kind of study showcases the power of eDNA metabarcoding to answer some really interesting questions that were previously unobtainable due to the complexities and cost of such an exercise. Notwithstanding the problems associated with PCR primer bias and PCR stochasticity, the qPCR "spike-in" method is easy to implement and will likely become a standardised technique in the field. Further studies will examine and improve on it.
Overall I found the manuscript to be clear and easy to follow for the most part. I did not identify any serious weaknesses or concerns with the study, although I am not able to comment on the more complex statistical procedures such as the "unified information-theoretic causality" method devised by the authors. The section on limitations of the study is important and acknowledges some issues with interpretation that need to be explained. The methods, while brief in parts, are clear. The code used to generate the results has been made available via a GitHub repository. The figures are clear and attractive.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors convincingly show multiple inner and outer leaflet non-protein (lipid) densities in a cryo-EM closed state structure of GLIC, a prokaryotic homologue of canonical pentameric ligand-gated ion channels, and observe lipids in similar sites during extensive simulations at both resting and activating pH. The simulations not only corroborate structural observations, but also suggest the existence of a state-dependent lipid intersubunit site only occupied in the open state. These important findings will be of considerable interest to the ion channel community and provide new hypotheses about lipid interactions in conjunction with channel gating.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This is an interesting study from Admin Peng's laboratory that builds on previous work by the PI implicating Greatwall Kinase (the mammalian gene is called MASTL) in checkpoint recovery.
The main claims of this study are:
1) Greatwall stability is regulated by the E6-AP ubiquitin ligase and this is inhibited following DNA damage in an ATM dependent manner.<br /> 2) Greatwall directly interacts with E6-AP and this interaction is suppressed by ATM dependent phosphorylation of E6-AP on S218<br /> 3) E6-AP mediates Greatwall stability directly via ubiqitylation<br /> 4) E6-AP knock out cells show reduced ATM/ATR activation and quicker checkpoint recovery following ETO and HU treatment<br /> 5) Greatwall mediated checkpoint recovery via increased phosphorylation of Cdk substrates
In my opinion, there are several interesting findings presented here but the overall model for a role of the E6-AP -Greatwall axis is not fully supported by the current data and will require further work. Moreover, there are a number of technical issues making it difficult to assess and interpret the presented data.
Major points:
1) The notion that Greatwall is indeed required for checkpoint recovery hinges on two experiments shown in Figures 5A and B where Greatwall depletion blocks the accumulation of HELA cells in mitosis following recovery from ETO treatment and in G2/M following release from HU. An alternative possibility to the direct involvement of Greatwall in checkpoint recovery could be that Greatwall in HeLA cells is required for S-phase progression (as for example Charrasse et al. suggested). A simple control would be to monitor the accumulation of mitotic cells by microscopy or FACS following Greatwall depletion without any further checkpoint activation.
2) The changes in protein levels of Greatwall and the effects of E6-AP on Greatwall stability are rather subtle and depend mostly on a qualitative assessment of western blots. Where quantifications have been made (Figures 2D and 4F) the loading control and the starting conditions for Greatwall (0 timepoints in the right panel) appear saturated making precise quantification impossible. I would argue that the authors should at least quantify the immuno-blots that led them to conclude on changes in Greatwall levels and make sure that the exposure times used are in the dynamic range of the camera (or film). A more precise experiment would be to use the exogenously expressed CFP-Greatwall that is described in Figure 6 and measure the acute changes in protein levels using quantitative fluorescence microscopy in live cells. This is, in my opinion, a lot more trustworthy than quantitative immuno-blots.<br /> I also note here that most experiments linking Greatwall levels to E6-AP were done using siRNA, while the E6-AP ko cells would be a more reliable background for these experiments, especially with reconstituted controls.
3) This study has no data linking the effects of Greatwall to its canonical target PP2A:B55. The model shown in Figure 9 is therefore highly speculative. The possibility that Greatwall could act independently of PP2A:B55 should at least be considered in the discussion given the lack of experimental evidence.
4) The major effect of E6-AP depletion on the checkpoint appears to be a striking reduction in ATM/ATR activation, suggesting that this ubiquitin ligase is involved in checkpoint activation rather than recovery. It is not clear if this phenotype is dependent on Greatwall. If so it would be hard to reconcile with the default model that E6-AP acts via the destabilisation of Greatwall. In the permanent absence of E6-AP, increased Greatwall levels should inactivate B55:PP2A. How would this lead to a decrease in ATM/ATR activation? This is unlikely, and indeed Figure 5E shows that the reduction of MASTL in parallel to E6-AP does not result in elevated levels of ATR/ATM activation. Conversely, the S215A E6-AP mutant does have a strong rescue impact on ATR/ATM (Figure 8D).
5) In summary, I do not think that the presented experiments clearly dissect the involvement of E6-AP and Greatwall in checkpoint activation and recovery. E6-AP depletion has a strong effect on checkpoint activation while Greatwall depletion is likely to have various checkpoint-independent effects on cell cycle progression.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This paper describes a novel synthetic lethal interaction between BRCA2 loss and the cytokinesis regulators, including ROCK. The SL effects are restricted to short-term in vitro assays, and the underlying mechanisms remain largely elusive. The impact of the work in its current form is limited.
Strengths:<br /> - A novel synthetic lethal (SL) interaction, which appears independent from the -BRCA2 SL interaction that depends on replication fork stalling and DNA damage induction.<br /> - The SL interaction is validated in a panel of genetic models of BRCA2 deficiency.<br /> - The SL interaction can be induced using clinically approved agents.
Weaknesses<br /> - The evidence that this SL interaction is independent of replication defects is not solid.<br /> - The SL interaction is based on chemical inhibitors only, with 6 out of 9 ROCK inhibitors not demonstrating the SL interaction.<br /> - The mechanisms by which ROCKi specifically affects BRCA2-defective cells are elusive.<br /> - It remains unclear what the cause of the multiple mitotic defects is.
Combined, it remains unclear if the identified SL interaction is therapeutically meaningful. Clinical stage inhibitors are available, and various BRCA2-deficient cancer models have been described, allowing the authors to address this in long-term in vitro assays and in vivo assays. Also, the authors describe multiple phenotypic consequences, but the order of events and the reason why the effects are specific to BRCA2 remain largely unclear. Furthermore, the notion that the observed effects are independent of replication defects requires further substantiation.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Zheng et al., investigated the molecular and functional mechanisms of two homeodomain missense mutations causing human retinal photoreceptor degeneration diseases in photoreceptor development regulated by the CRX transcription factor. They analyzed the E80A mutation associated with dominant cone-rod dystrophy (CRD) and the K88N mutation associated with dominant Leber Congenital Amaurosis (LCA). The authors found that E80A CRX binds to the same target DNA sites as WT CRX, but the binding specificity of K88N CRX is altered from that of WT in an in vitro assay. They generated Crx(E80A) and Crx(K88N) KI mice and performed ChIP assay and observed that K88N CRX binds to novel genomic regions from the WT-binding sites, while E80A binds to the WT sites. In addition, using the KI mice, they found that E80A and K88N differently affect the expression of Crx target genes. This study is well executed with proper and solid methodologies, and the manuscript is clearly written. This study gives us the insights how single missense CRX mutations lead to different types of human retinal photoreceptor degeneration diseases.
While the study has strengths in principle, it has a couple of weaknesses. One is how well E80A KI mice function as a pathological model of dominant CRD, in which cones are mainly first affected, is not clearly shown in this study. More data investigating how cones are affected by performing histological, molecular, and physiological analyses will be helpful and useful. For example, in the Discussion, the authors describe that E80A associates with S-cone opsin promoter results is "data now shown". This data must be presented for the readers. In addition, more molecular insights as to how E80A affects cones will strengthen this study. Another point is that it will be very valuable if the authors could show how E80A and K88N differently affect the 3D structure of the CRX homeodomain. Even a simulation model would be valuable.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this work from Zhou et al., the authors address mechanisms of mitotic chromosome size scaling during development. Their approach, which employs complementary use of in vivo (Xenopus embryos) and in vitro systems (Xenopus extracts), rendered investigation of this relationship experimentally tractable and allowed the authors to convincingly demonstrate that mitotic chromosome scaling is mediated by differential loading of maternal chromatin remodeling factors during interphase. The authors show that this scaling is dependent on an increasing nucleo-cytoplasmic (N/C) and that condensin I is titrated away from chromosomes as the N/C ratio is increased. Interestingly, the authors found that spindle and nuclei did not scale with changes in N/C ratio, suggesting that although mitotic chromosome scaling correlates with spindle and nuclei scaling, it is mechanistically distinct. Complementary Hi-C analyses of chromatin architectures of both larger condensin I-rich chromosomes and smaller condensin I-poor chromosomes support a condensin-based looping model to explain the inverse relationship between chromosome-associated condensin and chromosome length, however, this model seems somewhat contrived due to inherent limitations of the approach. A characterization of an independent importin-α-dependent mitotic chromosome scaling mechanism, though potentially interesting, is too premature to be included and a bit of a non sequitur in terms of the overarching narrative and major findings of the work. Though there is some room for improvement in terms of image analysis and measurements, the work is well-written, comprehensive in scope, and addresses a fundamental biological question. Furthermore, the authors' major conclusions and substantive claims are well-supported by the experimental results.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The Covid-19 pandemic has had major adverse impacts on cancer screening globally. Despite this, most prior reports have not included observations from LMICs. This paper aims to address this important gap.
Because comparable data were not available across the countries reported here, comparisons would not be appropriate, so the authors chose a case study design, which was a prudent decision and a strength of the work.
The authors make use of data from IARC's CanScreen5 reporting system, which is completely appropriate. In addition, this aspect serves to demonstrate the usefulness of the CanScreen5 system, as it can be used to support this type of study. National data were not available in all countries.
The main findings in the paper describe the early impact of the Covid-19 pandemic on cancer screening participation for the screening programs reported on in the 6 countries that were selected.
I would anticipate that, having demonstrated that this type of case study focusing on cancer screening in LMICs is feasible, this would encourage others to conduct further studies among LMICs, which would be welcomed by the field.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The abstract and introduction framework asserts that ketamine's enhancement of excitatory synaptic drive in the hippocampus is presumed to underlie its rapid antidepressant effects. This is not the only, and perhaps not the primary effect mechanism suggested by prior experiments, also strongly implicating disinhibitory effects in the prefrontal cortex as necessary and sufficient to mediate antidepressant effects. Nevertheless, it is valuable to seek mechanistic motifs that provide multiple paths for explaining the seemingly counterintuitive effects where NMDAR blocker enhances excitatory transmission. These need not be conserved across brain regions and cell classes. The primary result of this study demonstrates that 1 hr-long ketamine application to cultured cells reduces calcineurin and GCaMP activity to elevate AMPA receptor subunit GluA1 phosphorylation and enhance the expression of Ca2+-permeable, GluA2-lacking (CP-)AMPARs. These observations are then evaluated in vivo, where calcineurin shows a similar response to ketamine and CP-AMPAR antagonist-abolished ketamine effects on behavior in the open field and tail suspension tests. One significant uncertainty this study helps resolve is whether GluA2-containing AMPARs are removed from synapses or whether GluA2-lacking AMPARs are inserted following ketamine administration. GCaMP imaging, FRET and glutamate uncaging assays provide a strong complement to biochemistry and in vivo data. There are several significant technical and conceptual limitations in this work, which substantially limit the extent of conclusions that can be drawn at this point.
1. The age of neurons in cell culture experiments was 14 days in vitro (DIV), representing developing cultures that are just starting to form synapses. How these effects carry over to more mature cultures or adult animals is unclear.
2. Phosphorylation analyses, forming the foundation of this work, are carried out 1 hr after ketamine treatment. This is prior to the observed clinical effects of ketamine and this point should be acknowledged. Whether and how long this effect lasts remains to be examined. If the goal is to highlight the earliest likely effects of ketamine that should precede potential clinical effects, this should be acknowledged, and in that case, the onset of effects should be clarified. At this point, the temporal features remain undersampled, with a single time-point.
3. A lower dose (50%) treatment was used to evaluate potential sex differences in ketamine effects, which is not sufficiently justified, except post hoc based on behavioral data. The discussion section does consider potential factors that can account for observed differences.
4. The 1-hr timeline to behavioral testing is fast, relative to clinical effects on behavior as well as behavioral effects measured in most studies using mouse models.
5. Tail suspension test is broadly acknowledged as an inadequate model of antidepressant effects.
6. There is no evidence from the in vivo experiments that effects in the hippocampus are due to direct actions of ketamine, as those reported for the cell culture studies. Intraperitoneal injections cannot be used to localize primary effects in vivo to the hippocampus, which would require local delivery.
7. If (MNI)-caged L-glutamate was used at 1 μM concentration, as stated in methods, this is considerably below typical concentrations reported in the literature.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this paper by Banerjee et al., the authors described the potential role of two universal stress proteins in M. smegmatis and M. tuberculosis in regulating intracellular free cAMP concentration, which was a unique observation. The experiments were logically designed to prove the expression and interactions; it would have been worthwhile to explore beyond to gain an insight into how the changing levels of free cAMP could modulate any key phenotypes in the bacteria such as virulence, antibiotic resistance, etc. in the content of knockout/knockdown and overexpression of MSMEG_3811 and Rv1636 in individual organisms. The preliminary data of natural inhibitor STOCKIN43384 impacting the survival of M. smegmatis was interesting, but authors need to prove the MOA by using knockdown and overexpression strains of Rv1636.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The evolution and control of the three-part life history of holometabolous insects have been controversial issues for over a century. While the functioning of broad as a master gene controlling the pupal stage and of E93 as a master gene for the adult stage has been known for about a decade or more, chinmo has only recently been proposed as being the master gene responsible for maintaining the larval stage (Truman & Riddiford, 2022). While the former paper focused on the embryonic and early larval function of Chinmo, this paper explores its metamorphic effects and defines the roles of Broad and E93 in the phenotypes produced by manipulations of Chinmo expression.
Overall, the paper is well presented but in places, readers would be helped if the authors were more explicit about the logic and details of their manipulations. There are a couple of conceptual issues that the authors should address.
The role of Broad in larval tissues:<br /> One intriguing issue relates to the relationship of Chinmo to Broad and E93 in larval versus imaginal tissues prior to metamorphosis. The knock-down of chinmo in imaginal discs results in severe suppression of growth and the lack of metamorphic patterning genes such as cut and wingless. Normal growth and patterning are reestablished though, if broad is also knocked-down, supporting the notion that the effects of the lack of Chinmo are mediated through the premature expression of Broad.<br /> In the salivary glands, by contrast, chinmo knock-down suppresses growth, and this growth suppression is not reversed by simultaneous broad knockdown. They properly conclude that the role of Chinmo in supporting the growth of larval tissues does not involve Broad, but their data on the expression of salivary gland proteins suggest that Broad still plays some role in Chinmo function in salivary glands. Fig. 5E shows the levels of various salivary glue proteins in the glands of Chinmo knock-down larvae. The levels are reduced, as expected by the lack of salivary gland growth, but a significant finding is that they are there at all! The Costantino et al. (2008) paper shows that these genes are only induced in the mid-L3. Ecdysone, acting through Broad isoforms, is necessary for their appearance and these SGS genes can be induced in the L1 and L2 stages by ectopic expression of some Broad isoforms. Their low levels in Fig 5, would be due to the small size of the gland, but the gland's premature expression of Broad likely causes their induction. In larval cells, then, Chinmo may feed into two parallel pathways, one that does not involve broad and regulates growth and the other, utilizing Broad, regulating premetamorphic changes.<br /> It would be useful to look at early larval salivary gland proteins such as ng-1 to -3 that are expressed in salivary glands before the critical weight. Also, it would be interesting if the appearance of the SGS proteins after chinmo knock-down (Fig 5E) is abolished by simultaneous knock-down of broad.
Role of Chinmo and Broad in Hemimetabolous insects:<br /> In the conclusion of their comparative studies on the cockroach (line 342), the authors state that Broad exerts no role in the development of hemimetabolous insects. However, this conclusion is not consistent with the literature. The first study of broad knockdown in a hemimetabolous insect was in the milkweed bug Oncopeltus fasciatus by Erezyilmaz et al. (2006). Surprisingly to Erezyilmaz et al., broad knock-down in early-stage nymphs did not cause premature metamorphosis. However, Broad expression was essential for tissues of the wing pads and dorsal thorax to undergo morphogenetic growth (rather than simple isomorphic growth), and for stage-specific changes in coloration through the nymphal series (but not for the nymph to adult color change). A similar function for Broad on wing growth during the later nymphal stages was later shown in Blattella (Fernandez-Nicolas et al., 2022; Huang et al., 2013). The wing- and genital pads represent "imaginal" tissues in the nymph and the need for Broad in these tissues are the same as seen in imaginal discs as the latter shift from isomorphic growth to morphogenesis at the critical weight checkpoint in the L3.<br /> This would suggest that important roles for Broad and E93 are already established in the hemimetabolous insects with E93 controlling the shift from immature (nymphal) to adult phenotypes and Broad controlling the premetamorphic growth of imaginal tissues in early-stage nymphs. Chinmo might then be needed to keep both in check.
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Reviewer #2 (Public Review):
Like humans, Bengalese finches rely on auditory feedback to maintain the acoustic stability of their learned vocalizations, and deafening causes acoustic degradation of their songs. How disruptions to sensory input alter gene expression in brain regions important for singing and song learning remains relatively unexplored. The authors develop an innovative serial laser capture RNA-sequencing method, which allows them to conduct large-scale analyses of gene expression in spatially defined singing-related regions, as well as in surrounding non-singing-related regions. These methods are used to demonstrate that deafening preferentially alters gene expression in song-related regions relative to surrounding song-related areas, and that deafening reduces correlations in gene expression between connected song-related regions. The authors then compare their findings to a previous single-cell RNA sequencing dataset to determine the cell types whose gene expression is likely to be most strongly affected by deafening and song degradation. Finally, the authors repeat their measurements of gene expression changes in RA following unilateral lesion of LMAN and find that LMAN lesions have the largest effect on groups of genes whose expression was also strongly affected by deafening. The study is elegant and rigorous, and its conclusions are well-supported. This work reveals candidate genes that may play a role in stable vocal performance and whose changes in expression may contribute to the acoustic degradation of vocal performance following deafening.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Neurons of the inferior olive exhibit strong subthreshold oscillations, and drive complex spiking through climbing fiber synapses onto Purkinje cells in the cerebellar cortex. This activity plays an essential role in coordinating motor control and the induction of cerebellar plasticity. In this study, the authors make use of optogenetic and electrophysiological approaches to examine the interplay between intrinsic oscillations and two important excitatory and inhibitory input populations to the inferior olive. The authors show that excitation is enhanced when it occurs in the rebound phase of the preceding inhibition. Using a computer model, the authors also show that enhanced excitation can effectively recruit larger populations of neurons, presumably through gap junctional coupling. The strengths of the study include the authors' ability to independently control both excitatory and inhibitory pathways, as well as the rigorous and systematic examination of input timing and amplitude and their effects on spike output. There were some weaknesses; high variability in cell resting potentials raised questions about how cell health impacted the findings, and there needed to be better documentation of recording conditions and parameters. There also needed to be a more extensive discussion about the nature of input timing and frequency under behaviorally relevant conditions. Given these relatively minor issues, the study provides new insight and depth into synaptic integration in the inferior olive and adds to our understanding of how input timing is translated into climbing fiber signals.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The authors report a study comparing self-reported stable and unstable knees with total knee arthroplasty. Advanced imaging methods (dynamic fluoroscopy with model-image registration) and analysis of muscle activities were used to characterize the study subjects during three ambulatory activities (level gait, downhill walking, and stair descent).
The subject cohort all received one design of TKA in a similar time period. The unstable subgroup was >60% female, while the stable knee cohort was 70% male, which is a notable limitation. The measurement methods are state-of-the-art and expertly applied.
The results suggest there may be measurable differences in knee kinematics in subjects with unstable knees, but this was not strongly supported across groups. Rather it was highlighted in 3 individuals who self-reported instability during the test session. The muscle activity analysis supports there being differences between the stable and unstable knee groups.
Despite the limitations of a small subject cohort with only a single TKA design, the study highlights important methods that appear suitable to further study the factors contributing to clinical dissatisfaction with TKA as it relates to joint stability and function during ambulatory tasks.
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Reviewer #2 (Public Review):
In this manuscript, Villalobos-Cantor et. al. described a new technique for cell-type specific in vivo labeling of nascent peptides, which they call POPPi. POPPi is based on sequence-independent incorporation of the puromycin analog OPP into an elongating peptide, which also simultaneously terminates the growing peptide. To achieve cell-type-specific labeling, the authors used an OPP derivative, PhAc-OPP, as the labeling substrate. PhAc-OPP contains a blocking group that prevents it from incorporating into the growing peptide, and the blocking group can be cleaved off by the enzyme PGA, which is expressed in the cell type of interest.
The authors validated POPPi in different cell types in the Drosophila brain and showed that this method could be used to image general translation or to biochemically enrich nascent peptides in a cell-type-specific manner. They also showed that with an optimized labeling protocol, it is possible to achieve efficient labeling with minimum effect on animal viability and health. The authors further used POPPi to provide independent support for a previously known phenomenon: age-dependent decline in general translation in the neurons. The results of this work are solid, and the main conclusions are well supported by the data presented. The manuscript is very well written with a clear logic flow and is very easy to read.
What is less clear is how generally useful POPPi will be to the community. The authors pointed out two major cell-type specific applications of POPPi, 1) imaging general translation and 2) biochemically purifying nascent peptides. For application #1, although POPPi might be a more desirable method in some cases, a combination of non-cell-type specific labeling using OPP, and marking the cell type of interest by a fluorescent protein might be simpler. Because labeling with OPP eliminates the enzymatic step that converts non-reactive PhAc-OPP to reactive OPP, the labeling kinetics can be improved, and the toxicity associated with PGA expression can be avoided. For application #2, a currently widely used strategy for a similar purpose is various types of ribosome profiling techniques. Ribosome profiling may be easier to perform than POPPi, and because proteins cannot be amplified, a very large quantity of starting materials will be needed if one wants to use POPPi to characterize cell-type specific nascent proteome. In fact, in this manuscript, the authors used western blots to detect candidate proteins and did not use mass spec to characterize the nascent proteome.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The work from Nakajima-Takagi et al describes the phenotypes and study of a PCGF1 mutant mouse model. PCGF1 is a core component of the non-canonical PRC1.1 complex and specific functions of this complex in hematopoiesis. Using somatic inactivation models, the authors demonstrate that the acute deletion of PCGF1 from adult hematopoiesis leads to a progressive myeloid bias in the bone marrow and peripheral blood. This occurs at the expense of the HSPC compartment, with a reduction in all populations and of the lymphoid committed populations. The myeloid bias is cell intrinsic, as competitive transplant of the PGCF1 deficient bone marrow recapitulates the phenotype. The effect is not due to exhaustion or loss of self-renewal of the HSCs.<br /> To understand the basis for the myeloid bias, the authors first assessed transcriptome signatures and see a shift in gene expression programs related to myeloid development and targets of the key myeloid transcription factor C/EBPa. Further analysis demonstrated an increased expression of Cebp1 in the PCGF1-deficient LSK cells. Reducing the expression of Cebpa could modify the myeloid skewing of Pcgf1 deficient cells in culture. This de-repression of Cebpa correlates with changed local H2AK119ub1 levels in the HPSC populations.
Additional studies assessed how the loss of Pcgf1 changed the response to hemoablation, in this instance with a single dose of 5-FU. This study coupled with scRNA-seq suggested that PRC1.1 was important in regulating the GMP populations, potentially through a self-renewal program. This led to a focussed analysis of the GMPs, with evidence for altered Hoxa9 and b-catenin levels contributing to the altered GMP behaviours. Both have been implicated and demonstrated to have functional roles in these programs in other studies.
Finally, ageing of Pcgf1 deficient mice demonstrated that these mice were predisposed to developing T-ALL and MPN. The authors provide a characterisation of these moribund states and their phenotypes are consistent with the diagnosis.
Overall the work demonstrates a specific requirement for Pcgf1, and therefore PRC1.1, in the regulation of hematopoiesis. I think the authors largely achieved the aims and the results are supportive of the conclusions. The work shows myeloid bias, experimental evidence that this is due to a derepression of a myeloid lineage program in the HPSC and associated chromatin changes, and functions for Pcgf1 in both hematopoietic regeneration and malignancy. This suggests a unique role for non-canonical PRC1.1 compared to canonical PRC 1.
Strengths:<br /> - in vivo experiments and evidence;<br /> - multiple lines of evidence supporting the conclusion;<br /> - mechanistic studies provide direct evidence of the proposed mechanism.
Weaknesses:<br /> - can the authors demonstrate normal maturation of the myeloid lineages as this would be important to differentiate between myeloid bias and a block in myeloid differentiation? This is important to distinguish between.<br /> - include analysis of mature myeloid cells and FACS plots to allow assessment of maturation.
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Reviewer #2 (Public Review):
In this manuscript, Niethamer et al. investigate the role of the transcription factor ATF3 in lung regeneration after H1N1 influenza. They focus on endothelial ATF3 which is present in a subset of lung capillaries in the adult mouse lung. Interestingly, they found that influenza infection upregulates endothelial ATF3 and that endothelial deletion of Atf3 results in impaired regeneration, leading to enlarged airspaces after viral infection. They further show that this effect may be due to an increase in apoptosis and a decrease in proliferation, suggesting that endothelial ATF3 is necessary for pulmonary vascular regeneration, as well as recovery of the alveolar architecture.<br /> Given the recent publications in the field describing lung endothelial heterogeneity, as well as its possible role in injury repair, this work is relevant to the community. It also supports the idea that epithelial-endothelial crosstalk is important for lung regeneration and proposes a potential candidate for this process.
Strengths:<br /> The authors identified and tested the role of endothelial Atf3 in lung regeneration using well-established techniques. They identified this transcription factor as a candidate using state-of-the-art scRNA-seq. They also carefully lineage traced ATF3 expressing cells using an inducible reporter before and after infection and then used a pan-endothelial driver Cdh5 to delete Atf3 specifically in the endothelium. Thus, the authors successfully show significant changes in the alveolar structure after infection in their mutant model.
Weaknesses:<br /> Although there is evidence that the author's claims have biological relevance, this paper would benefit from strengthening and/or clarifying some things:
• The scRNA-seq analysis is performed in two separate objects ("control lung" and "H1N1 infected lung 14dpi"). For these two sets of data to be comparable, the authors should have integrated the objects and analyzed them together. This is not only important for deciding the clusters' identities and making sure that the same clusters are compared between control and infected, but also necessary to compare gene expression.<br /> • ATF3 is not only present in Cap1_B, in the infected lung there seems like Cap1_A express less ATF3. The authors should comment on this difference.<br /> • It is unclear how the clusters Cap1_A and Cap1_B were decided. The manuscript would benefit from clarification.<br /> • It would be beneficial to see via immunofluorescence the morphological and spatial differences between ATF3-expressing and non-expressing endothelial cells since this transcription factor is expressed in multiple endothelial cell types.<br /> • The authors mention ATF3 is not endothelial-specific. Expression of ATF3 in other cell types should be evaluated via immunofluorescence.<br /> • The authors should have shown evidence of the deletion in their Atf3EC-KO mouse and addressed whether they had residual ATF3. If there is no antibody available, RNAscope could be used, or Western Blot or RT-PCR on sorted endothelial cells.<br /> • The authors only show the epithelium as evidence that the alveolar region is altered in their mutant after infection. The endothelium should have also been investigated, especially since their mutant is an endothelial-specific deletion. Within this, the different endothelial cells should have been assessed by a method other than RNAscope such as immunofluorescence, given that this method is unable to show morphology and there are antibodies available.<br /> • Bulk RNA-seq from endothelial cells is used in the manuscript. However, because ATF3 is not specific to Cap1_B cells or even capillaries alone, the downstream gene expression analysis of bulk RNA should be placed into the context of lung endothelial heterogeneity.<br /> • Although the authors mentioned that the infection with H1N1 influenza can have regional differences, they do not show how they picked regions for their analysis and quantification, and whether ATF3 upregulation was found in more severely affected regions. Furthermore, since they quantified via FACS, this heterogeneity in the infection itself could have affected their observations.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
1) A detailed step-by-step approach to validation of some previously known outcomes.<br /> 2) Useful for more focus to be placed on data from the second half of the paper.<br /> 3) Some reflection on the media used to study paracrine effects is needed - more experiments here would be beneficial.<br /> 4) Path clamp experiments - how does bath solution alter the effect of any limited paracrine effect - we are removing cells from the treatment media and putting them in physiological solutions - an opportunity to recover?
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This study assessed the inflammatory and metabolic profiles of a healthy sub-Saharan Africa (Tanzania) population versus a healthy population outside Africa (Dutch). Using plasma samples from these cohorts, an O-Link proteomics inflammatory panel and targeted metabolomics platforms were utilised. The study shows that 'healthy' Tanzanians display an enhanced pro-inflammatory phenotype versus Dutch volunteers. Specific pathways and metabolites identified included - increase activation of the Wnt/Beta catenin pathway, and the metabolites 4E-BP1 and FGF21. The study highlights some interesting findings regarding the impact of diet on inflammatory pathway activation.
Major Strengths & Weaknesses - This is an interesting study and approach that aims to address some challenging questions in underrepresented populations. The findings demonstrate the importance of diet and dietary interventions on metabolic health, as well as key inflammatory proteins. It does raise the question whether anti-inflammatory therapies need to be targeted to specific at-risk populations, more so than other populations.
Impact - The study demonstrates the importance of considering differences between populations and the inclusion of underrepresented populations in such studies. The data suggests that lifestyle changes in sub-Saharan Africa are potentially contributing to altered inflammatory and metabolic profiles. Thus, health initiatives advocating traditional diets may alleviate the NCD epidemic in sub-Saharan Africa.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors combine NMR experiments, cell experiments, and molecular simulations to address the question of how lipid interactions of the prolactin receptor contribute to signalling. They assess the interactions of the disordered cytoplasmic tail of the receptor with phosphoinositides among others by chemical shift perturbations from NMR for different PIP2-containing membranes, by coarse-grained simulations, as well as site-directed mutagenesis and subsequent cell signalling experiments to monitor the activation of the mutants. A major result is that PIP2 interactions are functionally important, which so far has not been known for this receptor. Their results are likely relevant for other non-receptor tyrosine kinases.
The hypothesis that the protein complex is regulated by IDR-membrane interactions is very novel. A major strength is the close connection of and feedback between state-of-the-art experiments and simulations.
This is where I see weaknesses:<br /> 1. The motivation of focusing on LID1 is limited.<br /> 2. The data and analysis for the JAK2-PRLR complex appear somewhat superficial, and a connection between conformational states to their functional relevance is lacking. In fact, the majority of the simulation part of the paper is about suggesting different states of the PRLR-JAK2 complex but the states and their hypothesized functional relevance are not further taken up, e.g. by experiments, and yet presented as major results, e.g. in the abstract.<br /> 3. The connection between simulations and mutational study is not very direct.<br /> An open question is if the mutants can distinguish between the effects of PRLR-PIP2 interaction or PRLR-JAK2 interaction, even though this conclusion is still drawn from the data.<br /> 4. The conclusions drawn from the mutagenesis study (lines 547-555) are not directly supported by data. Only a partial correlation between PRLR membrane localisation and STAT5 activation is no reason to attribute the unexplained part of the STAT5 activation to PRLR-JAK2 interactions without further studies.<br /> 5. PIP2 is identified as an important regulator, with very solid support from the presented data. PIP3 is part of the model but not discussed before or as part of the results. The analysis could be similarly applied or the data directly relevant to the understanding of PIP3 plays a similar role, as interactions are likely primarily electrostatically driven.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In A. Ruppel, et al, the authors study the mechanics of one cell, two cells, and cell monolayers upon a transient local activation of contractility. First, the authors characterize the tractions and stress maps (measured via Traction Force Microscopy and Monolayer Stress Microscopy, resp.) for one and two cells in the absence of contractility activation, and found a correlation between the principal stress direction and actin fiber orientation. Next, the authors use the theory of foams to infer, combining traction force data and cell geometry data, the mechanical parameters of cells like the line tension or the force of adherent fibers. Next, the authors activate contractility by means of optogenetic tools on one half of the system and quantify the response on both halves, concluding that the receiver half response is driven by active processes, increasing contractility for two cells, while fluidizing for one cell. Next, the authors estimate the level of active response in cell doublets by comparing the stress maps to numerical simulations of a thin elastic medium with anisotropic contractility. By varying aspect ratios of the H pattern, the authors find a correlation between the principal stress direction and the orientation of stress fibers and find that the previous active response is in general enhanced when the principal stress direction is perpendicular to the orientation of the fibers. Finally, these features are also found in a cell monolayer for a fixed confinement aspect ratio.
Overall, the manuscript contains a broad characterization of the steady state mechanics and the dynamical response to the activation of contractility for one cell, two cells, and cell monolayers.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors hypothesized that PTH1R and ZFP467 could constitute a feedback loop that facilitates PTH-induced osteogenesis and that conditional deletion of Zfp467 in osteogenic precursors would lead to high bone mass. Using a number of methods, they have established a regulatory feedback mechanism of this transcription factor and the PTH receptor in osteoblastic precursors as well as showing that PrrxCre deletion of Zfp467 causes an increase in trabecular bone mass, while AdipoCre does not. Nevertheless, they have not established the actual mechanism of action of the transcription factor nor which gene it acts on in the osteoblast. They have mostly achieved their aims and the results partially support their conclusions. However, the work is descriptive and does not address the central issue of how ZFP467 acts. At present, its impact on the field is limited.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript introduces a novel assay in a 'phenomics' approach to address an important aspect of S. aureus pathogenesis. The authors set out to identify mutations that arise during clinical S. aureus infections that cause a decrease in intracellular host-cell toxicity and increase intracellular persistence. To do this, they use a 'phenomics' approach. For phenotype, they quantify HeLa cell toxicity for each strain in a panel of 387 clinical S. aureus isolates. This is done by measuring HeLa cell death induced by intracellular S. aureus via propidium-iodide uptake. The whole genomes of each of these 387 isolates had previously been sequences. They use the genomic data and phenotype data to carry out a genome-wide association study (GWAS) looking for genetic signatures that correlate with reduced HeLa cell cytotoxicity. As expected, mutations in agr were the strongest locus-level signal, but the study did identify one agr-independent mutation in ausA, which was able to be independently validated, showing that the assay is robust enough to find causal mutations. The analysis is thoughtful, the assay appears robust, and I think the discussion of conclusions and limitations is mostly valid. Thus, my concerns are focused on further understanding the practical utility of the approach and whether or not the HeLa cell model recapitulates what happens in professional phagocytes. For example, it is not clear to me that this system has the statistical power to find novel, biologically relevant rare mutations without first being very mindful in selecting strains that are extremely genetically similar. It is also not clear to me that the toxicity assay captures the important features of the intracellular persistence that occurs in vivo within professional phagocytic cells. Thus, given these practical limitations and a somewhat artificial model system, the impact on the field is likely to be moderate in nature. However, the analysis and approach taken could be re-purposed to any robust quantitative phenotype, and this will certainly be of great interest to others that study bacterial evolution in clinical contexts.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Krishnan, et al describe a unique and powerful approach to assessing the role of genetic variation on mitochondrial and cardiac function and health. Utilizing a panel of inbred mouse strains, on which they performed proteomics on heart samples, they measured 840 mitochondrial proteins and correlated these data to heart function using two heart stress models. This resulted in a number of correlative observations, three of which were explored in more detail to connect three specific genes to cardiac hypertrophy. This is an interesting dataset and there is clearly value in what is presented. The data were largely correlative, however, and there are only a couple of causation-oriented experiments. It's hard to adjudicate between these strengths and weaknesses in determining the overall impact of the manuscript.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript reports on mermithid nematode fossils from amber which dates from the Cretaceous period. The specimens described in the manuscript consist of insects and associated nematodes which have been trapped in amber and fossilised. The nematodes have been identified as belonging to the Mermithidae family, a family of nematode worm that infect insects.
The findings of this manuscript provide an insight into the evolution history of nematodes and parasitism. Despite the ubiquity of both nematodes and parasites in extant ecosystems, fossil records of both are very rare. This is because nematodes and many parasites are soft bodied, and many are located inside their hosts' bodies, thus they rarely become fossilised. Thus, most of what is known about the evolutionary history of nematodes, and evolution of parasitism are based on what could be inferred from extant examples.
The specimens described in this manuscript provides a valuable contribution to our understanding of parasitism in the geological past. These amber specimens are a snapshot of parasite-host interactions - interactions which are commonly found in nature but are rarely captured in fossils. The identification of the specimens as mermithid nematodes are based on sound scientific reasoning. The worms' morphology and position in relation to the insects are consistent with what have been observed with extant mermithid nematodes.
Additionally, one of the values of such parasite fossils is that they provide us with insight into parasite-host combinations or interactions which may have existed throughout the geological past, but no longer exist today or cannot be inferred from extant taxa. It helps fill in major gaps in our understanding of parasitism. This was the case with the amber fossil that contained a bristletail with its nematode parasite.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This very interesting study uses a combination of high channel count neural recordings and machine learning to characterize neural representations of complex natural and synthetic sounds in the inferior colliculus. The authors use deep neural networks to model sound evoked activity in a large number of IC multiunits with high accuracy in gerbils with normal hearing and hearing loss. They then use the DNNs to simulate activity evoked by a wide range of stimuli and demonstrate systematic differences in latent population representations between normal hearing and hearing-impaired animals. Models for hearing impaired animals show activity consistent with impaired representations of speech in noise. These results lay the groundwork for a potentially valuable approach to improving signal processing in hearing aids and prosthetics.
The large speech dataset and clean hearing loss effects are particularly impressive. While the approach and associated data are novel and likely to be of broad interest, there are some substantial concerns about the study. First, the authors fail to acknowledge substantial previous work on super-threshold activity in cortex of animals with hearing loss, making it appear that they overstate the novelty of the current results. There are also many cases where they fail to clearly report the details of statistics used to support their claims. Finally, while the accuracy of the DNN models is compelling for the speech stimuli in the data set, it is not clear that the comparisons of simulated activity reflect actual neural activity in the stimulus conditions tested.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In the study by Li et al., the authors hypothesize that RELMa, a macrophage-derived protein, plays a sex-dimorphic role as a protective factor in obesity in females vs males. The authors perform largely in vivo studies utilizing male and female WT and RELMa KO mice on a high-fat diet and perform an in-depth analysis of immune cell composition, gene expression, and single-cell RNA Sequencing. The authors find that WT females are protected from obesity and inflammation vs males, and this protection is lost in female RELMa KO mice. Further analysis by the authors including flow cytometry of the visceral fat SVF in female WT mice showed reduced macrophage infiltration, higher levels of eosinophils, and Th2 cytokine expression compared to WT male mice and female KO mice. The authors show that protection from obesity and inflammation in female RELMa KO mice can be rescued with an injection of eosinophils and recombinant RELMa. Lastly, the authors use single-cell RNA-Sequencing to further analyze SVF cells in WT and KO male and female mice on a high-fat diet.
Overall, we find that the study represents an important finding in the immunometabolism field showing that RELMa is a key myeloid-derived factor that helps influence the macrophage-eosinophil function in female mice and protects from diet-induced obesity and inflammation in a sexually dimorphic manner. Overall, the study provides strong and convincing data supporting the authors' hypothesis and conclusion.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Yamaguchi et al. studied the roles of two proteins, Calaxin and Armc4, in the assembly of the outer arm dynein (OAD) docking complex (DC). By combination of the improved cryo-ET analysis and gene knockout zebrafish lacking each of these proteins, they found that Armc4 plays a critical role in the docking of OAD and that Calaxin stabilizes the molecular interaction in the docking.They further showed an evidence that Calaxin changes the conformation of another compartment of DC comprising CCDC151/114. This new information provides an important basis for understanding how the DC is assembled and regulates docking of OAD. The authors' conclusion is well supported by the data but some data presentation and discussion need to be completed.
Gui et al. (2021) already reported on a cryo-EM observation in bovine tracheal cilia, with the conclusion similar to this paper in the structure of OAD/DC on DMT. Using knockout zebrafish strain, the authors present detailed interaction of calaxin with other DC components. They show that the binding of calaxin induces the changes of conformation in N-terminal region of CCDC151/114. The conformation further changes in the presence of Ca2+; specific conformation of N-terminal region of CCDC151/114 becomes undetectable, instead additional structure appears in the vicinity of calaxin.
1) The authors conclude that the Ca2+-dependent conformational change of DC is subtle and not dynamic. This result is eventually valuable information but may be somewhat unexpected from the point of view that calaxin plays an important role in the regulation of flagellar motility in Ciona sperm. The authors found that calaxin changes the conformation of N-terminal CCDC151/114 region but the core dynein structure shows no dynamic change. What about the changes in the interaction between calaxin, core dynein, and DMT? Is this beyond the resolution of cryo-ET analysis?
2) It would be very helpful if the authors could add the cryo-ET images of calaxin-/- axoneme in the presence of 1 mM EGTA in Figure 7. Although these images are thought to be similar or identical to Figure 4F, it would help to confirm that the conformational changes in CCDC151/114 and additional part of DC are induced in a Ca2+-dependent manner.
3) To clarify the molecular interaction of calaxin with other components, it would also be helpful if the authors add the images rotated 80 degree to Figure 4F and G, in similar way in Figure 7,
4) Despite the molecular phylogenetic difference, there are several similarities between calaxin and Chlamydomonas DC3, not only in the in situ structure and configuration but in the phenotype of mutants; Chlamydomonas mutant lacking DC3 shows OAD loss in the distal part of a flagellum (Casey et al, MBC, 2003). It may be a good reference if the authors add the position of DC3 in Figure 4. A', B', and C.
5) There is a significant difference in sperm motility between WT and calaxin-/- or WT and armc4-/- (Figure 2E). However, it is not clear whether immotile sperm were included in the data for VAP (Figure 2F) or BCF (Figure 2G). For example, WT and calaxin-/- show similar VAP, although both are significantly different in the percent of motile sperm.
6) In calaxin-/- mouse, OAD was clearly detected from the base to two-thirds of a flagellum with unclear border (Figure 2A). Typical distribution of OAD+class and OAD-class are shown in Figure 5 in the ~3 micrometer tomograms. Were these taken from around this unclear border? Are proximal most region of a flagellum occupied with OAD+class only? The authors should clearly indicate the region of a flagellum where the tomograms in Figure 5C and D were selected.
7) Line 229~: It is not clear what the authors meant by "probably reflecting the different distance from the sperm head". In relation to this and the comment 6, does the "proximal" in the sentence "OAD loss occurred even in the proximal part of the flagella" (line 232) indicate the region near the base of a flagellum?
8) In conjugation with comment 7, it would be appreciated to show an authors' idea on why distal region of flagella tends to lack calaxin, if they do not discuss anywhere in the text,
9) Immunofluorescence in twister-/- epithelial cilia showed that the localization of calaxin is independent of OAD (line 271-274). Based on the authors' finding, the localization of calaxin requires Armc4, which is preassembled with calaxin in the cytoplasm. If this is true and the localization of calaxin is NOT resulting from diffusion, Armc4 must be localized with calaxin along the entire length of cilia in twister-/- epithelial cilia (Figure 6D). Although Armc4 is shown localized in cryo-ET images (e.g. Figure 1, Figure 7), authors may provide the immunofluorescence of Armc4 along the entire length of sperm flagella and epithelial cilia.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study, Rmus and colleagues contribute to the important open question of whether reinforcement learning deficits observed in older adults are due to impairments in basic learning processes, or can be attributed to a decline in working memory function. The authors present cross-sectional behavioral data from a task designed to assess the role of working memory in reinforcement learning. And they use computational modeling in conjunction with MR spectroscopy to demonstrate a relationship between prefrontal glutamate and age-related impairments in learning specific to working memory decay. I found the overall story compelling, the data novel, and the analysis carefully executed. Below I outline some areas in which the claims of the manuscript could be strengthened.
1. I may have missed this, but does glutamate correlate with other model parameters? Or did the authors only focus on the WM parameters because of the age difference? In support of the specificity argument, it would be important to show that glutamate only predicts WM related parameters regardless of whether there was an age difference or not.<br /> 2. As it is somewhat common with these tasks, it seems like the model does not fully capture the performance deficit in OA (Fig. 2B), even when all the individual difference parameters in WM are allowed to vary. Can the authors say more about the discrepancy? This is an interesting datapoint which may give clues to mechanism.<br /> 3. Relatedly, it may not be possible with these data alone, but can authors discuss what the WM decay parameter captures? In particular for OA, the distinction between generating and maintaining a "task set" has been extensively written about. Older adults tend to have difficulty internally generating and flexibly deploying task sets, but somewhat paradoxically can perform better than YA in certain decision situations (e.g. when reward is dependent on previous choices, see Worthy et. Al. 2011). The task in this study necessarily pushes OA in a regime in which relying on familiar decision strategies is sub-optimal, and task sets must be continuously generated. Is there a type of intervention do authors expect would reverse the observed deficit in WM?<br /> 4. There is a wealth of evidence suggesting striatal DA loss in older adults, which served as the basis for many of the original investigations and hypotheses regarding a simple RL deficit in OA (e.g. work by Shu-Chen Li and others). While the authors do not directly measure DA in this study, it would be helpful to place the results in the context of that literature.<br /> 5. Finally, the main argument of the paper as I read it is that PFC glutamate mediates the performance deficits observed in RL because it reflects a compromised WM system. Sample size permitting, it would be helpful to see a formal test of this mediation relationship.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript by Aderounmu presents an interesting attempt to reconstruct evolution of the function of the helicase domain in ancestral Dicers, RNase III enzymes producing siRNAs from long double-stranded RNA and microRNAs from small hairpin precursors. The helicase has a role in long dsRNA recognition and processing and this function could have an antiviral role. Authors show on reconstructed ancestral Dicer variants that the helicase was losing dsRNA binding affinity and ATPase activity during evolution of the lineage leading to vertebrates while an early divergent Dicer-2 variant in Arthropods retained high activity and seemed better adapted for blunt ended long dsRNA, which would be consistent with antiviral function.
The work is consistent with apparent adaptation of vertebrate Dicers for miRNA biogenesis and two known modes of substrate loading: "bottom up" dsRNA threading through the helicase domain where the helicase domain recognizes the end of dsRNA and feeds it into the enzyme and "top-down" where the substrate is first anchored in the PAZ domain before it locks into the enzyme. Some extant Dicer variants are known to be adapted for just one of these two modes while Dicer in C. elegans exemplifies an "ambidextrous" variant. The reconstruction of the helicase domain complex enabled authors to test how well would be ancestral helicases supporting the "bottom up" feeding of long dsRNA and whether the helicase would be distinguishing blunt-end dsRNA and 3' 2 nucleotide overhang. Although the reconstruction of an ancestral protein from highly divergent extant sequences yields just a hypothetical ancestor, which cannot be validated, the work provides remarkable data for interpreting evolutionary history of the helicase domain and RNA silencing in more general. While it is not surprising that the ancestral helicase was a functional ATPase stimulated by dsRNA, particularly new and interesting are data that the decline of the helicase function started already at the level of the common deuterostome ancestor and the helicase was essentially dead in the vertebrate ancestor. It has been reported two decades ago that human Dicer carries a helicase, which has highly conserved critical residues in the ATPase domain but it is non-functional (10.1093/emboj/cdf582). Recently published mouse mutants showed that these highly conserved residues are not important in vivo (10.1016/j.molcel.2022.10.010). Aderounmu et al. now suggest that Dicer carried this dead ATPase with conserved residues for over 500 million years of vertebrate evolution.
I do not have any major comments to the biochemical analyses and while I think that the ancestral protein reconstruction could yield hypothetical sequences, which did not exist, I think they represent reasonable reconstructions, which yielded data worth of interpretations. My major criticism of the work concerns clarity for the readership and interpretations of some results where I wish authors would clarify/revise the text. The following three examples are particularly significant:
1) It should be explained to which common ancestor during metazoan evolution belongs the ancestral helicase AncD1D2 or at least what that sequence might represent in terms of common ancestry during metazoan evolution.
2) This is linked to the first point - authors work with phylogenetic trees reconstructed from a single protein sequence, which are not well aligned with predicted early metazoan divergence (https://doi.org/10.1098/rstb.2015.0036). While their sequence-based trees show early branching of Dicer-2 as if the two Dicers existed in the common ancestor of almost all animals (except of Placozoa), I do not think there is sufficient support for such a statement, especially since antiviral RNAi-dedicated Dicers evolve faster and Dicer-2 is restricted to a few distant taxonomic group, which might be better explained by independent duplications of ambidextrous ancestral Dicers. I would appreciate if authors would discuss this issue in more detail and make readers more aware of the complexity of the problem.
3) Authors should take more into the account existing literature and data when hypothesizing about sequences of events. Some decline of the helicase activity is apparent in AncD1DEUT suggesting that it initiated between AncD1D2 and AncD1DEUT. This implies that a) antiviral role of Dicer was becoming redundant with other cellular protein sensors by then and b) Dicer was already becoming adapted for miRNA biogenesis, which further progressed in the lineage leading to vertebrates to the unique top-down loading with the distinct pre-dicing state where the helicase forms a rigid arm. Authors even cite Qiao et al. (https://doi.org/10.1016/j.dci.2021.103997) who report primitive interferon-like system in molluscs - this places the ancestry of the interferon response upstream of AncD1DEUT and suggests that this ancestral protein-based system was taking over antiviral role of Dicer much earlier. In fact, a bit weaker performance of AncD1LOPH/DEUT combined with the aforementioned interferon-like system and massive miRNA expansion in extant molluscs (10.1126/sciadv.add9938) suggests that molluscs possibly followed a convergent path like mammals. While I am missing this kind of discussion in the manuscript, I think that the model where "interferon appears ..." in AncD1VERT (Fig. 6) is incorrect and misleading.
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Reviewer #2 (Public Review):
In this work, Cunha et al provide an insightful and exhaustive analysis of the role of hypoxia and HIF-1a for T cell activation and function. The work contributes to the field by showing that transient hypoxia occurring simultaneously with T cell stimulation (antigen recognition) induces an effector program in T cells that results in increased cytotoxicity in vivo and in mouse models. Importantly, the induction of this effector phenotype is not necessarily linked with an increase in proliferation in vitro, and in vitro differences are mostly observed upon antigen re-challenging.
The major strengths of the work are the use of different complementary methods to modulate HIF-1a (low oxygen conditions, inhibition of PDH by FG-4592, and deletion of VHL) and the combination of mouse and human models, especially addressing how to implement the findings to the production of CAR-T cells. Besides, the authors not only evaluate T cell function but also dive into the pathways driving the responses observed, which provides mechanistic insight.
While activation of HIF-1a through the different means mentioned before results in similar signatures in terms of T cell effector phenotype and animal response, there are some aspects that differ between the models. This is probably indicating that low levels of oxygen have other effects beyond the regulation of HIF, and that pharmacological modulation of HIF-1a might not be exactly equivalent to HIF-1a stabilization by real hypoxia.
The work is useful to better understand the discrepancies in the field, where it has been previously shown that hypoxia can have both a pro-inflammatory effect and an immunosuppressive effect on T cells. The answer proposed by the authors is that it´s a matter of timing, and not so much the magnitude of the HIF-1a response. Despite this being relatively easy to control ex vivo, the challenge occurs when considering the role of hypoxia in vivo, which probably lasts longer than the transient hypoxia needed for beneficial effects on T cells, causing T cell exhaustion.
From the translational perspective, the study suggests strategies to improve CAR-T cell therapy but also has some limitations. Despite an improvement of cytotoxicity and survival observed in mouse models upon adoptive cell transfer or injection of CAR-T cells with previously increased HIF1a levels, these approaches do not result in curation and survival is still quite low in all groups. Interestingly, improved survival with HER2 CARs exposed ex vivo to low oxygen conditions for 1 day is clear and more promising.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This work formulates a detailed theoretical polymer physics model intended to explain the observed morphology of chromatin in the Drosophila cell nucleus. The model is examined in detail by both analytical calculation and computer simulation. The central premise of the suggested theory is that it is based on equilibrium statistical mechanics. Within this paradigm, authors explore the model that views chromatin fiber as a block copolymer and, most importantly, describes the role of RNA polymerase as it interacts with one of the copolymer blocks and regulates its effective solvent quality. Blocks are assumed to be fixed on the time scale of interest by, e.g., different levels of acetylation or methylation. RNA polymerase is supposed to interact only with one of the chromatin blocks, called active, and assumed interaction is quite peculiar. Namely, RNA polymerase complex may absorb on chromatin fiber and, the model assumes, the fiber decorated with absorbed RNA polymerase molecules is less sticky to itself, or more repulsive than the fiber itself. This peculiar assumption allows authors to make interesting predictions about how proteins can regulate the genome folding architecture.
STRENGTH
The work includes a rather detailed theoretical description of the model and its equilibrium statistical mechanics. As both analytical theory and accompanying simulation indicate, the assumptions put forward in formulating the model do indeed produce the desired morphology, with isolated regions ("micells") of core inactive chromatin surrounded by the less dense shell region in which RNA polymerization may potentially take place. Having such a detailed theory is potentially beneficial for the field and opens up avenues for further exploration.
WEAKNESS
The underlying assumption about the interaction of RNA polymerase complex with the fiber, although important and organic for the model, does not seem easy to justify from a molecular standpoint, especially thinking of the charges and electrostatic interactions.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The paper from Marchal-Duval et al reports for the first time the important role played by the transcription factor PRRX1, expressed specifically in the mesenchyme of the lung, in the context of fibrosis. The authors used a combination of human (Donor and IPF) and mouse lungs (saline and bleomycin treated) as well as associated fibroblasts and PCLS to test the functional role of PRRX1 in the context of proliferation and differentiation induced by TGFb1. The work is supported by an impressive amount of data (7 main figures and 14 supplementary figures).
A main weakness in this work is the counterintuitive result that PRRX1 is downregulated in human lung fibroblasts (from both IPF and Donor) treated with TGFb1. Another smaller weakness is the inactivation of Prrx1 in vivo using ASO starting at d7 post bleomycin treatment.
The strengths of this work are the multiple approaches used by the authors to test the role of PRRX1 in lung fibrosis. The results are statistically solid and informative. The results presented are extremely convincing to support their conclusion that PRRX1, downstream of TGFb1 signaling is important for fibrosis.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The work presented by Jordan and Keller aims at understanding the role of noradrenergic neuromodulation in the cortex of mice exploring a visual virtual environment. The authors hypothesized that norepinephrine released by Locus Coeruleus (LC) neurons in cortical circuits gates the plasticity of internal models following visuomotor prediction errors. To test this hypothesis, they devised clever experiments that allowed them to manipulate visual flow with respect to locomotion to create prediction errors in visuomotor coupling and measure the related signals in LC axons innervating the cortex using two-photon calcium imaging. They observed calcium responses proportional to absolute prediction errors that were non-specifically broadcast across the dorsal cortex. To understand how these signals contribute to computations performed by V1 neurons in layers 2/3, the authors activated LC noradrenergic inputs using optogenetic stimulations while imaging calcium responses in cortical neurons. Although LC activation had little impact on evoked activity related to visuomotor prediction errors, the authors observed changes in the effect of locomotion on visually evoked activity after repeated LC axons activation that were absent in control mice. Using a clever paradigm where the locomotion modulation index was measured in the same neurons before and after optogenetic manipulations, they confirmed that this plasticity depended on the density of LC axons activated, the visual flow associated with running, and the concurrent visuomotor coupling during LC activation. Based on similar locomotion modulation index dependency on speed observed in mice that develop only with visuomotor experience in the virtual environment, the authors concluded that changes in locomotion modulation index are the result of experience-dependent plasticity occurring at a much faster rate during LC axons optogenetic stimulations.
The study provides very compelling data on a timely and fascinating topic in neuroscience. The authors carefully designed experiments and corresponding controls to exclude any confounding factors in the interpretation of neuronal activity in LC axons and cortical neurons. The quality of the data and the rigor of the analysis are important strengths of the study. I believe this study will have an important contribution to the field of system neuroscience by shedding new light on the role of a key neuromodulator. The results provide strong support for the claims of the study.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This work presents an exhaustive study of inferred functional networks from in vitro neuronal cultures across several modalities: primary rat cultures (with varying densities and longitudinal points), and human iPSC monolayers from different cell types and organoids. The authors first estimated the functional connectivity of these networks from their spontaneous activity (recorded with high-density MEAs) and then tried to find which wiring principle could better explain the observations. By deploying generative network models (with 13 different wiring principles) they observed that models with homophilic wiring principles were systematically outperforming the other ones. This proposes a universal rule for how neurons connect, which is that they tend to connect with neurons that have many common neighbors.
One of the major strengths of this study is its scope. They analyzed sparse and dense primary rat cultures at 4 different time points during development (from 7 to 28 DIV in total) as well as with the pharmacological application of GABAA blockers; 3 different cell lines: spinal-cord motor neurons, dopaminergic neurons, and glutamatergic neurons, and organoid slices. However, the big scope of this study is also one of its weaknesses, the techniques presented here to analyze the data are used inconsistently; for some preparations, there's much more detail than in others, and the constant jump between preparations and methodologies makes the findings hard to follow.
Similarly, the number of samples used in some preparations (ranging from 6 to 12) appears to be insufficient, since the study relies on multiple comparisons across the results from 13 different generative models. In many cases, it is not possible to identify which results are significant and which aren't. Most of the methodology used in this study has been used before in the context of the human connectome project (Betzel et al, Neuroimage 2016); in there they used data from 380 total participants, which made the comparisons across all the different models much more robust.
Most previous research with generative models for neural connectivity has focused on structural connectivity. In there, the link between wiring principles, energetic costs, and network topology can be made. This study, however, focuses on functional connectivity (measured by the spike time tiling coefficient), where the link between these quantities is unclear. Although the authors highlight this point in the manuscript, the constant comparisons to structural connectivity concepts and studies often lead to confusion. A clear example of this is the section where the authors explore the effect of chronic GABAA receptor blockade. It is unclear whether the authors are trying to claim that this protocol alters the development of the structural network or only the dynamics. The former could have needed additional controls.
The authors have been diligent and thorough with their statistical testing and their claims are commensurate with that. However, given the large number of different types of results and tests being presented, it is often difficult to find the corresponding explanation in the methods.
This is valuable work for experimental and computational neuroscientists studying the development of neuronal networks and the link between structural and functional connectivity. It would greatly benefit from homogenizing the results, methods, and statistics across the different experimental preparations. The conceptual similarities and differences between structural and functional wiring principles also need to be emphasized.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In the present manuscript, Perrodin et al. investigated which properties of ultrasonic vocalizations determine their attractiveness for female mice. They collected a set of male courtship vocalizations and compared their attractiveness for female mice against a number of conditions, including silence, and a number of modified sequences.
The study has a clear design and used insightful modifications on the vocalization sequences, which allow the present results to be linked to previous results. The most interesting outcome of the study is that female mice prefer regularly timed sequences of vocalizations over less regularly timed sequences. This result is novel and adds to our understanding of the determinants of social communication between mice. Overall the study is likely underpowered, which was, however, hard to assess as animal numbers were largely not reported for the individual tests, and statistical analysis was carried out on the level of sessions only.
The study has a very good discussion embedding the current results with the previous literature, although the discussion steps beyond the results in a few respects, in particular when trying to determine the underlying reasons for the preference for regularly spaced sequences.
Methodologically the study is carried out at the appropriate level, although some improvements could be made to the experimental apparatus to avoid reflections.
The study will likely have a substantial impact on the field of mouse communication because the regularity of spacing has not been a focus of previous research. In addition, the confirmation that a lot of other modifications are less determining for the attractiveness of the vocalizations provides solid data on which to base future work.
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Reviewer #2 (Public Review):
The eleven paralogs of SLC26 proteins in humans exhibit a remarkable range of functional diversity, spanning from slow anion exchangers and fast anion transporters with channel-like properties, to motor proteins found in the cochlear outer hair cells. In this study, the authors investigate human SLC26A6, which functions as a bicarbonate (HCO3-)/chloride (Cl-) and oxalate (C2O42-)/Cl- exchanger, combining cryo-electron microscopy, electrophysiology, and in vitro transport assays. The authors provide compelling evidence to support the idea that SLC26A6's exchange anions at equimolar stoichiometry, leading to the electroneutral and electrogenic transport of HCO3-/ Cl- and C2O42-/Cl-, respectively. Furthermore, the structure of SLC26A6 reveals a close resemblance to the fast, uncoupled Cl- transporter SLC26A9, with the major structural differences observed within the anion binding site. By characterizing an amino acid substitution within the SLC26A6 anion binding site (R404V), the authors also show that the size and charge variance of the binding pocket between the two paralogs could, in part, contribute to the differences in their transport mechanisms.
The strength of this work lies in the reductionist, in vitro approach that the authors took to characterize the transport process of SLC26A6. The authors used and developed an array of functional experiments, including two electrogenic transport assays - a fast kinetic (electrophysiology) and a slow-kinetic (fluorescent-based ACMA) - and two electroneutral transport assays, probing for Cl- (lucigenin) and HCO3- (europium), which are well executed and characterized. The structural data is also of high quality and is the first structure of an SLC26 coupled anion exchanger, providing essential information for clarifying our understanding of the functional diversity between the SLC26 family of proteins.
To my knowledge, the outward-facing conformational state has not been determined for any mammalian SLC26 paralog, which limits the mechanistic interpretation of transport and is a weaker point of this manuscript. However, this is a very minor point.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this work, the authors investigate the role of CRB3 in the formation of the primary cilium both in a mouse model and in human cells. They confirm in a conditional knock-out (KO) mouse model that Crb3 is necessary for the formation of the primary cilium in mammary and renal epithelial tissues and the new-born mice exhibit classical traits of ciliopathies. In the mouse mammary gland, the absence of Crb3 induces hyperplasia and tumorigenesis and in the human mammary tumor cells MCF10A the knock-down (KD) of CBR3 impairs ciliogenesis and the formation of a lumen in 3D-cultures with less apoptosis and spindle orientation defects during cell division.
To determine the subcellular localization of CRB3 the authors have expressed exogenously a GFP-CRB3 in MCF10A and found that this tagged protein localizes in cell-cell junctions and around pericentrin, a centrosome marker, while endogenous CRB3 localizes at the basal body. To dissect the molecular role of CRB3 the authors have performed proteomic analyses after a pull-down assay with the exogenous tagged-CRB3 and found that CRB3 interacts with Rab11 and is present in the endosomal recycling pathway. CRB3 KD also decreases the interactions between components of the γTuRC complex. In addition, the authors showed that CRB3 interacts with a tagged-Rab11 by its extracellular domain and that CRB3 promotes the interaction between Rab11 and CEP290 while CRB3 KD decreased the co-localization of GCP6 with Rab11 and γTub. Finally, the authors showed that CRB3 depletion cannot activate the Hh pathway as opposed to the Wnt pathway.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript by Minkowicz et al., investigates the presence of neuronal ensembles in the striatum that may encode grooming (as a model of a naturalistic behavior). They implemented a semi-automated detection of grooming, and by recording populations of striatal cells they show that individual neurons in the striatum contain activity modulations around the start, end, or during grooming. Then using this activity they identify ensembles of cells in individual sessions/animals at the start, end or during grooming.
The behavioral tracking and recordings are remarkable, the manuscript is clearly written and the finding mostly sound with the proposed conclusions, providing original findings in the field. Nonetheless some points are raised that need further clarification
1. When claiming that the findings show encoding of transitions into or out of grooming (and duration of grooming) one could expect to see specific regressions between the neuronal activity (of individual cells or ensembles) and the parameters mentioned besides the analysis shown in figure 3 and 5.<br /> 2. Was the detection of ensembles presented in figure 4 sensible to use less than 5 seconds before/after grooming. I am thinking that 5 seconds are times that could contain behaviors that may have their own ensembles. Why 5 seconds?<br /> 3. According to Figure 2-figure supplement 1. The recordings were performed covering the lateral and in some cases the central part of the striatum. Shall it be specified along the text where the specific recordings come from?
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors embarked on a study to identify SNPs in clinical isolates of S. aureus that influence sensitivity to serum killing. Through a phenotypic screen of 300 previously sequenced S. aureus bacteremia (SAB) isolates, they identified ~40 SNPs causing altered serum survival. The remainder of the study focuses of tcaA, a gene with unknown function. They show that when tcaA is disrupted, it results in increased resistance to glycopeptides and antimicrobial components of human serum.
They perform an elegant series of experiments demonstrating how a tcaA knockout is more resistant to killing by whole serum. arachadonic acid, LL-37 and HNP-1. They provide compelling evidence that in the absence of tcaA resistance to arachidonic acid is mediated through release of wall teichoic acids from the cell wall, which acts as a decoy and sequesters the fatty acid.
Similarly, they suggest that resistance to cationic antimicrobial peptides is through alteration of the net charge of the cell wall due to loss of negatively charged WTAs based on reduced cytochrome C binding.
They continue to show that tcaA is induced in the presence of human serum, which causes increased resistance to the glycopeptide teichplanin.
They propose that tcaA disruption causes altered cell wall structure based on morphologic changes on TEM and increased sensitivity to lysostaphin and increased autolysis via triton x-100 assay.
5, Finally, they propose that tcaA influences mortality in SAB based on raw differences in 30-day morality. Interestingly they do decreased fitness during murine bacteremia model compared to wild-type.
Strengths:
1. The manuscript is well-written and easy to follow<br /> 2. The identification of SNPs leading to altered serum killing is convincing and valuable data<br /> 3. The mechanism for tcaA-mediated resistance to arachadonic acid and AMPs is compelling and novel<br /> 4. The murine infection data demonstrating that tcaA mutants exhibit reduced virulence is important data
Weaknesses:
1. Some of the conclusions are not supported by the data shown (either missing or incomplete)<br /> 2. The authors conclude that tcaA mutants show reduced peptidoglycan crosslinking. This conclusion is based on qualitative TEM images and increased sensitivity to lysostaphyin/autolysis. While these data are suggestive. it is difficult to draw such a conclusion without analysis of the cell wall by LC-MS (such as http://doi.org/10.1371/journal.ppat.1009468).<br /> 3. The authors conclude "TcaA contributes to increased disease severity in mice and humans". While it seems biologically plausible that a polymorphism known to increase glycopeptide MIC affects mortality, the human data presented is based on raw 30-day mortality numbers. It is misleading to make the association with mortality without adjusting for confounding variables known to influence mortality in SAB (e.g. age, comorbidities, presence of sepsis, endocarditis, duration of bacteremia). Also, with just 12 patients in the SNP group, this is likely underpowered to detect any difference.
Overall, I think this is a good submission and the majority of their conclusions are supported by the data. The mechanism behind the clinically relevant tcaA mutation is important, given its known role in glycopeptide resistance and therefore likely clinical outcomes. This manuscript would benefit with the inclusion of some additional experiments to help support their finding.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this work, the authors reported cryo-EM structures of four types of zinc-binding site mutants of a bacterial Zn2+/H+ antiporter YiiP, and proposed distinct structural/functional roles of each of the binding sites in the intramolecular Zn2+ relay and the integrity of the homodimeric structure of YiiP. MST analysis using the mutants with a single Zn2+-binding site at different pH further clarified the pH dependence of Zn2+ binding affinity of each site. Moreover, the inverse Multibind approach refined the CpHMD pKa values of the key Zn2+-binding residues so that they agreed with the MST data. Consequently, energetic coupling of Zn2+ export to the proton-motive force has been suggested. These findings definitely provide new mechanistic insight into this Zn2+/H+ antiporter.
Regrettably, the resolutions of the cryo-EM structures presented in this work are, overall, not high enough to describe detailed structure of some specific regions including the Zn2+-binding sites, and the density is missing for some important regions including the kinked segment of TM5. Further attempts toward higher resolution cryo-EM maps would be beneficial to corroborate their conclusions. Additionally, it may, in a sense, appear that the MD simulations have been carried out forcibly so that the outcomes are compatible with or nicely explain the experimental data. Although this is not unusual or unacceptable, I am concerned that the determined pKa values of some residues, especially of Asp residues at Site A, are unusually high. These outcomes seem to need careful interpretation and discussion.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Zacharopoulos et al. investigated the relationship between MR spectroscopy-detected neurotransmitter concentrations (GABA/glutamate) in the intra-parietal sulcus (IPS) and middle frontal gyrus (MFG), behaviourally measured indices of sensory and cognitive processing, and fMRI measured functional connectivity within the frontoparietal network. They find that increased IPS glutamate concentration is related to poorer visuomotor processing in younger participants and better performance in older participants, while IPS GABA predicts the opposite pattern. They further show that these relationships are mediated by frontoparietal functional connectivity. Finally, they show that IPS GABA and glutamate concentration are related to fluid intelligence and that this relationship is mediated by visuomotor processing and moderated by the developmental stage. These data add to our understanding of the dynamic role of excitatory and inhibitory neurotransmitter systems in cognitive processes throughout development.
Strengths:
The study employs an impressively large cross-sectional, multimodal, dataset, with almost 300 participants ranging from 6 to 18+ years old.
The main finding (i.e., the interaction between GABA/Glu, visuomotor processing, and age) is found across three behavioural tasks and replicated in a second dataset collected 1.5 years after the first.
The authors extensively report the results of the numerous analyses performed in the supplementary material.
Weaknesses:
Pre-registration of experimental and analytical plans should be the norm, e.g., to reduce so-called 'p-hacking'. I am by no means asserting that this behaviour has occurred in the current study; however, it is disappointing that there is no reported pre-registration for such a large-scale study, where the selection and order of analyses (and the subsequent corrections applied) can meaningfully influence the pattern of results.
Many tests were performed in the study using frequentist statistics, and the way the results are reported makes it difficult to discern how distinguishable those that were reported as meaningful are from those that were disregarded.
Insufficient analyses were conducted to describe the relationships between a) GABA and glutamate, b) repeated behavioural measures, and c) test-retest reliability. This reduces the strength of the claims, some of which could be accounted for by simpler, potentially less interesting, explanations.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The mechanisms of action potential firing were studied by whole-cell patch-clamp recordings in acute brain slices of the zebra finch. The study builds on the initial finding by Zemel et al. (2021) that the action potentials of robustus arcopallialis projection neurons (RAPNs) have an exceptional small half-duration of about 0.2 ms at 40C. The authors, therefore, set out to investigate the mechanisms of action potential repolarization. They use an impressive set of complementary techniques including voltage clamp and current clamp recordings, pharmacological interventions with classical and novel subunit-specific blockers, in situ hybridization, and comparative genomics of the KCNC/Kv3 potassium channel genes. The data convincingly demonstrate that the Kv3.1 but not Kv3.2-Kv3.4 nor Kv1.1/1.2/1.6, Kv7, or BK channels mediate the rapid repolarization. The manuscript is clearly written and the data and the presentation of the data are of the highest scientific quality. The study is of interest to a broad readership because the zebra finch is a fascinating and novel model to investigate the mechanisms of rapid motor control. The similarities of these neurons of the zebra finch with the specialized Betz cells in the motor cortex of humans and other primates demonstrates the exciting advantages of this animal model in comparison with well-established rodent models to investigate the mechanisms of complex sensory-motor control in vertebrates.
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Reviewer #2 (Public Review):
This paper is an interesting and novel addition to our understanding of the link between ER stress and lipid homeostasis. Utilizing a genetic screen to determine modulators of the UPRER, Garcia, G., et al., determine C. elegans cannot activate the UPRER as strongly with knockdown of the putative hydroxysteroid dehydrogenase let-767. Additionally, let-767 knockdown results in smaller lipid droplets and changes to ER morphology. Both lipid droplet size and ER morphology size can be restored with supplementation of lipids, while the defect to UPRER activation persists. The authors elegantly show that one impact of let-767 knockdown on UPR is downstream of XBP1 splicing. The authors then go on to show that in mammalian cells, the lipid precursor 3-oxoacyl-CoA can cause a similar reduction to UPRER activation to that seen in C. elegans with let-767 knockdown. Some limitations of this study are that let-767 exact role in lipid metabolism is not well understood and it is unclear what the impact of let-767 knockdown in C. elegans has on lipid composition. It is also unclear mechanistically how let-767 is able to effect UPRER, as the authors show one potential mechanism is by blocking activation of the UPR downstream of XBP1 splicing. While the authors demonstrate that high levels of 3-oxoacyl-CoA can cause a reduction in the UPR response in mammalian cells, this finding is not recapitulated in C. elegans, nor does the study determine whether this compound accumulates in a let-767 knockdown.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Aimon et al. used fast whole-brain imaging to investigate the relationship between walking and neural activity in adult fruit flies. They find that increases in brain-wide activity are tightly correlated with walking behavior, and not with grooming or flailing, and are independent of visual input. They reveal that excitatory, inhibitory, and neuromodulatory neurons all contribute to brain-wide increases in neural activity during walk. Aimon et al. extend their observations of brain-wide activity to reveal that activity in some inferior brain regions is more correlated with walk than in other brain regions. The authors further analyzed their imaging dataset to identify candidate brain regions and cell types that may be important for walking behavior, which will be useful in hypothesis generation in future studies. Finally, the authors show that brain-wide activity is similar between spontaneous and forced walk and that severing the connection between the ventral nerve cord and central brain abolishes walk-related increases in brain activity. These results suggest that increases in brain-wide activity during walking may be largely attributed to sensory and proprioceptive feedback ascending to the central brain from the ventral nerve cord rather than to top-down executive and motor control programs. The observations presented in this study suggest hypotheses that may be tested in future studies.
Strengths: This paper presents a rich imaging dataset that is well-analyzed and cataloged, which will be valuable for researchers who use this paper for future hypothesis generation. The comparison of many different reagents, imaging speeds, and behavioral conditions suggests that the observed increases in brain-wide activity during walking are quite robust to imaging methods in adult fruit flies.
Weaknesses: This study is largely observational, and the few experimental manipulations presented are insufficient to support the author's broad claims about the generation of brain-wide neural activity.
Notably, the authors suggest that their image analysis can reveal individual cell types that are important for walking by matching their morphologies to registered components from whole-brain imaging experiments. While these predictions are a useful starting point for future experiments, they have not convincingly shown that their method can identify individual cell types in genetic reagents with more restricted expression patterns. Adding further validation to show that genetically subtracting the candidate neurons from the overall expression pattern of the calcium indicator abolishes that component from the response would strengthen this claim. Furthermore, imaging the matched candidate neuronal cell type to show that it recapitulates the activity dynamics of the proposed component would add additional evidence.
In addition, increases in neural activity prior to walk onset in specific brain regions are intriguing but insufficient to demonstrate the neurons in these regions trigger walking. This claim should await further studies that employ targeted and acute manipulation of neural activity, as noted by the authors. Furthermore, that activity in these brain regions is significantly increased prior to walk onset awaits more rigorous statistical testing, as do the authors' claims that spontaneous versus forced walking alters these dynamics. The suggestion that walking increases brain-wide activity via feedback from the ventral nerve cord is an interesting possibility and would also benefit from additional experimental validation. Activating and silencing neurons that provide proprioceptive feedback from the legs and determining the effect of this manipulation on brain-wide neural activity would be a good starting point.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study, Tomasi et al identify a series of tRNA modifying enzymes from Mtb, show their function in the relevant tRNA modifications and by using at least one deleted strain for MnmA, they show the relevance of tRNA modification in intra-host survival and postulate their potential role in pathogenesis.
Conceptually it is a wonderful study, given that tRNA modifications are so fundamental to all life forms, showing their role in Mtb growth in the host is significant. However, the authors have not thoroughly analyzed the phenotype. The growth defect aspect or impact on pathogenesis needs to be adequately addressed.
- The authors show that ΔmnmA grows equally well in the in vitro cultures as the WT. However, they show attenuated growth in the macrophages. Is it because Glu1_TTC and Gln1-TTG tRNAs are not the preferred tRNAs for incorporation of Glu and Gln, respectively? And for some reason, they get preferred over the alternate tRNAs during infection? What dictates this selectivity?
- As such the growth defect shown in macrophages would be more convincing if the authors also show the phenotype of complementation with WT mnmA.
An important consideration here is the universal nature of these modifications across the life forms. Any strategy to utilize these enzymes as the potential therapeutic candidate would have to factor in this important aspect.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this publication, the authors provide a comprehensive trajectory of transcriptional changes in Müller glia cells (MG) in the regenerating retina of zebrafish. These resident glia cells of the retina can differentiate into all neural cell classes following injury, providing full regenerative capabilities of the zebrafish retina. The authors achieved this by using single-cell RNA sequencing of Müller glia, progenitors, and regenerated progeny, comparing uninjured and light-lesioned retinae.
The isolation strategy involves using two transgenic strains, one labelling dividing cells and their immediate progeny, and the other Müller glia cells. This allowed them to separate injury-induced proliferating and non-reactive Müller glia cells. Subsequent single-cell transcriptomics showed that MG could be non-reactive under both uninjured and lesioned conditions and reactive MG give rise to a cell population that both replenishes the pool of MG and replenish neurogenic retinal precursor cells. These precursor cells produce regenerated neurons in a developmental time series with ganglion cells being born first and bipolar cells being born last. Interestingly hybrid populations have been detected that co-share characteristics of photoreceptor precursors and reactive glia.
This is the first study of its kind following the dynamic changes of transcriptional changes during retinal regeneration, providing a rich data source of genes involved in regeneration. Their finding of transcriptionally separable MG populations is intriguing.
This study focuses on the light-lesioned retina and leaves open the question if the observed transcriptional trajectories of regenerating neurons are generalizable to other lesion models (e.g. chemical or mutational lesions) or are specific to the light-damaged retina.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors sought to characterize normal placental aging to better understand how the molecular and cellular events that trigger the labor process. An understanding of these mechanisms would not only provide insight into term labor, but also potential triggers of preterm labor, a common pregnancy complication with no effective intervention. Using bulk transcriptomic analysis of mouse and human placenta at different gestational timepoints, the authors determined that stabilization of HIF-1 signaling accompanied by mitochondrial dysfunction and cellular senescence are molecular signatures of term placenta. They also used in vitro trophoblast (choriocarcinoma) and a uterine myocyte culture system to further validate their findings. Lastly, using chemically induced HIF-1 induction in vivo in mice, the authors showed that stabilization of HIF-1 protein in the placenta reduced the gestational length significantly.
The major strength of this study is the use of multiple model systems to address the question at hand. The consistency of findings between mouse and human placenta, and the validation of mechanisms in vitro and in vivo modeling are strong support for their conclusions. The rationale for studying the term placentas to understand the abnormal process of preterm birth is clearly explained. Although the idea that hypoxic stress and placental senescence are triggers for labor is not novel, the comprehensiveness of the approach and idea to study the normal aging process are appreciated.
There are some areas of the manuscript that lack clarity and weaknesses in the methodology worth noting. The rationale for focusing on senescence and HIF-1 is not clearly given that other pathways were more significantly altered in the WGCNA analysis. The placental gene expression data were from bulk transcriptomic analyses, yet the authors do not explicitly discuss the limitations of this approach. Although the reader can assume that the authors attribute the mRNA signature of aging to trophoblasts - of which, there are different types - clarification regarding their interpretation of the data and the relevant cell types would strengthen the paper. Additionally, while the inclusion of human placenta data is a major strength, the differences between mouse and human placental structure and cell types make highlighting the specific cells of interest even more important; although there are correlations between mouse and human placenta, there are also many differences, and the comparison is further limited when considering the whole placenta rather than specific cell populations.
Additional details regarding methods and the reasons for choosing certain readouts are needed. Trophoblasts are sensitive to oxygen tension which varies according to gestational age, and it is unclear if this variable was taken into consideration in this study. Many of the cellular processes examined are well characterized in the literature yet the rationale for choosing certain markers is unclear (e.g., Glb1 for senescence; the transcripts selected as representative of the senescence-associated secretory phenotype; mtDNA lesion rate).
Overall, the findings presented are a valuable contribution to the field. The authors provide a thoughtful discussion that places their findings in the context of current literature and poses interesting questions for future pursuit. Their efforts to be comprehensive in the characterization of placental aging is a major strength; few placental studies attempt to integrate mouse and human data to this extent, and the validation and presentation of a potential mechanism by which fetal trophoblasts signal to maternal uterine myocytes are exciting. Nevertheless, a clear discussion of the methodologic limitations of the study would strengthen the manuscript.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This preprint presents a compelling study examining the relationship between genotypic changes and phenotypic traits in bacteria over an extended period using the Long-Term Evolution Experiment (LTEE) as a model. The primary advances in methodology include employing high-resolution mass spectrometry for comprehensive metabolic profiling and combining it with previous gene expression and DNA sequencing datasets. This approach provides insight into how specific genetic mutations can alter metabolic pathways over 50,000 generations, enabling a deeper understanding of how genetic changes lead to observed differences in evolved bacterial strains. The findings reveal that evolved bacteria possess more diverse metabolic profiles compared to their ancestors, suggesting that these populations have uniquely adapted to their environment. The work also attempts to uncover the molecular basis for this adaptive evolution, demonstrating how specific genetic changes have influenced the bacteria's metabolic pathways.
Overall, this is a significant and well-executed research study. It offers new insights into the complex relationship between genetic changes and observable traits in evolving populations and utilizes metabolomics in the LTEE, a novel approach in combination with RNA-seq and mutation datasets.
However, the paper's overall clarity is lacking. It is spread too thin and covers many topics without a clear focus. I strongly recommend a substantial rewrite of the manuscript, emphasizing structure and readability. The science is well executed, but the current writing does not do it justice.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Hersperger et al. investigated the importance of Drosophila immune cells, called hemocytes, in the response to oxidative stress in adult flies. They found that hemocytes are essential in this response, and using state-of-the-art single-cell transcriptomics, they identified expression changes at the level of individual hemocytes. This allowed them to cluster hemocytes into subgroups with different responses, which certainly represents very valuable work. One of the clusters appears to respond directly to oxidative stress and shows a very specific expression response that could be related to the observed systemic metabolic changes and energy mobilization. However, the association of these transcriptional changes in hemocytes with metabolic changes is not well established in this work. Using hemocyte-specific genetic manipulation, the authors convincingly show that the DNA damage response in hemocytes regulates JNK activity and subsequent expression of the JAK/STAT ligand Upd3. Silencing of the DNA damage response or excessive activation of JNK and Upd3 leads to increased susceptibility to oxidative stress. This nicely demonstrates the importance of tight control of JNK-Upd3 signaling in hemocytes during oxidative stress. However, it would have been nice to show here a link to systemic metabolic changes, as the authors conclude that it is tissue wasting caused by excessive Upd3 activation that leads to increased susceptibility, but metabolic changes were not analyzed in the manipulated flies. The overall conclusion of this work, as presented by the authors, is that Upd3 expression in hemocytes under oxidative stress leads to tissue wasting, whereas in fact it has been shown that excessive hemocyte-specific Upd3 activation leads to increased susceptibility to oxidative stress (whether due to increased tissue wasting remains a question). The DNA damage response ensures tight control of JNK-Upd3, which is important. However, what role naturally occurring Upd3 expression plays in a single hemocyte cluster during oxidative stress has not been tested. What if the energy mobilization induced by this naturally occurring Upd3 expression during oxidative stress is actually beneficial, as the authors themselves state in the abstract - for potential tissue repair? It would have been useful to clarify in the manuscript that the observed pathological effects are due to overactivation of Upd3 (an important finding), but this does not necessarily mean that the observed expression of Upd3 in one cluster of hemocytes causes the pathology.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In whole exome sequencing of two patients suffering from MMAF syndrome, mutations of CCDC146 gene that result in premature stop codons were identified. The position of mutations could result in a truncated form of protein, thus whether these patients do indeed lack CCDC146 protein or if present, whether the truncated protein is functional, is unanswered by showing the CCDC146 protein localization only in the sperm from healthy donors. The main claim that CCDC146 protein is microtubule associated protein in the axoneme is well supported imaging expanded sperm flagellum to increase spatial resolution. However, the author's claim that the signal in the mid-piece is not specific is less supported by experimental evidence. The detection of CCDC146 in the sperm head is not further explored while TEM images show spermatogenesis defects in the manchette and acrosome formation. Increased detection of the CCDC146 protein in mouse sperm with sarkosyl supports its association with microtubules but does not exclude its potential role in the formation of sperm head. Overall, this study provides valuable information on CCDC146 function in male germ cells during spermatogenesis.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This study visualizes a specific localized form of cell-to-cell communication and conveys very well with what dynamics and sensitivity this biological phenomenon occurs.
Using a FRET-based PKA biosensor, the authors observed that radial localized kinase activity changes spontaneously occur in adjacent cells of certain cell density. This phenomenon of radial propagation of PKA activity changes in groups of cells was further mechanistically elucidated and characterized. Interestingly, the authors found that individual cells in the cell groups form spontaneous Ca2+ transients, which at a certain strength can trigger the biosynthesis and release of prostaglandin E2 (PGE2). PGE2 then acts on the neighboring cells and triggers the increase of cAMP levels and the associated activation of the PKA via G-protein-coupled receptors (EP2 and EP4). In systematic, well-structured experiments, it was then found that the frequency of occurrence of such radial activations depends not only on the cell density but also on the activation state of the ERK MAP kinase pathway. The authors skillfully used various modern genetically encoded biosensors and other tools such as optogenetic tools to visualize and characterize an interesting biological phenomenon of cell-to-cell communication. The insights gained with these investigations produce a better understanding of the dynamics, sensitivity, and spatial extent with which such communications can occur in a cell network. It is also worth noting that the authors have not limited the studies to 2D cell culture in vitro, but were also able to confirm the findings in an animal model.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study, Huang et al. investigated Bacillus velezensis, a species that colonizes plant roots as part of the rhizosphere. They showed that clone of B. velezensis SQR9 retains a division of labor of motile, planktonic subpopulation that do not produce extracellular matrix (ECM) and biofilm-forming sessile subpopulation that do produce ECM. Specifically, the sessile subpopulation secret toxins named bacillunoic acids (BAs) to kill some, but not all, of the planktonic subpopulation. The killing mechanism is mediated by a global regulator Spo0A, which co-activates BAs production and immunity, as well as ECM production. A strain that has a disrupted policing system revealed reduced biofilm formation, lower resistance to environmental stresses and alleviated ability to colonize plant roots. Overall, the toxin-mediated policing system is important for B. velezensis to mediate division of labor for enhancing population stability and ecological fitness when required (e.g., cell transition from a planktonic style to a multicellular style).
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Raykov et al. reported that TrafE, a member of the E3 ubiquitin ligase family similar to the TRAF proteins in mammalian cells, is essential for Dictyostelium discoideum to effectively respond to endolysosomal damage and defend itself against Mycobacterium marinum infection. First, the authors demonstrate that TrafE is recruited to the site of Mycobacterium-Containing Vacuole (MCV) damage along with ubiquitin molecules. This recruitment is necessary for the effective suppression of M. marinum growth in the cells. They also found that this response was not limited to the damage caused by M. marinum, but was also triggered by sterile damage caused by chemical compounds. Furthermore, the authors revealed that TrafE plays a role in the recruitment of Vps4 to sites of membrane damage and regulates the disassembly of ESCRT subunits. While TRAF6 has been previously implicated in ubiquitination in response to invaded bacteria in mammalian cells, this study provides solid data that furthers our understanding of the mechanism behind xenophagy. The authors conducted a thorough analysis to contribute to this field of research.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript "Rapid and precise genome engineering in a naturally short-lived vertebrate" describes the development of a CRISPR- based knock-in technology in Nothobranchius furzeri, or the African turquoise killifish, an innovative model species for studying aging and age-related disorders. While Tol2 systems had been demonstrated to be successful in generating reporter killifish lines, endogenous reporters via knock-in had not been reported so far. The major strength of the paper is that the authors show that they have been successful in developing 5 different knock-in fish lines with large inserts (up to 1.8kb) with high efficiency. They have inserted single or dual fluorescent reporters and demonstrated expression in line with the expected pattern. This is a breakthrough in the field and this method can be instrumental for many researchers working with unusual model species, and in particular, will expand the killifish community toolbox.
While this is very promising, the paper would benefit from a more rigorous validation of the KI lines that were generated. The authors did not show a co-localisation of the target gene expression with the reporter to prove bona fide reporting. In addition, it was not clear whether the KI affects the endogenous expression level of the target genes. The targeting efficiency of the method is high, but the quantifications are based on rather limited numbers of animals, which might not yet be very robust. A larger number of animals would have strengthened the efficiency conclusion.
The figures of the manuscript are well designed and support the conclusions, but several contain information that is not discussed in the main text, such as (un)expected bands on gels, reporter staining in WT animals, and unusual staining patterns. The body text seems to ignore these and only discusses findings that are in line with the story. A key point to the efficiency of the method seems to be a chemical modification of the repair template, which was not disclosed in the method section which at the moment hampers replication.
Finally, the discussion is brief and does not benchmark the method to other CRISPR-based KI methods in Xenopus or more typical model species such as mouse.
In conclusion, this paper describes a breakthrough method for a rising animal model that would benefit from a more thorough validation. Full disclosure of the methodology will boost the generation of genetically edited killifish lines and aid in the establishment of this promising animal model.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The goal of this study was to determine whether heartbeat-evoked responses measured at the scalp level with EEG, which followed regularity violations, could potencial help inform the diagnosis of patients with altered states of consciousness.
The authors use high density EEG and an oddball paradigm that probes violations of both local and global regularities. Four groups were considered including unresponsive wakefulness syndrome patents, minimally consciousness patients, emerging minimally consciousness patients and healthy controls. A difference was found between unresponsive and minimally conscious patients in the amplitude of the heartbeat evoked responses measure with EEG following a sound that violated a global regularity. Similarly, differences were found between the variance of these responses between the two above mentioned groups (N=58 and N=59), but no differences were found in relation to the healthy control group, which appear to be "in between" the two other groups (at least for global effect of HER). I thought this was a little counterintuitive and raises some questions about what this neural signature can tell us about the state of consciousness. Having said that, the healthy control sample was very small, more than 5 times smaller (only N=11).
In general, I thought the Discussion section was a little light on the implications of the findings, what they tell us about the brain mechanisms of consciousness and their different levels/states. A question is raised about whether it is necessary to lock EEG to heartbeats to find differences between patients. The data appeared to say that this is not the case but the discussion does not appear to reflect that very clearly.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
A distinguishing feature of live cells is that intracellular organelles move powered by molecular motors. However, the arsenal of molecular motors is limited relative to the vast variety of cargoes and processes involving long-distance movement. Cells cope with this mismatch by using adaptors that "bridge" a given molecular motor with a specific cargo, whose identity is dictated by peripheral membrane proteins, such RABs, or identity-determining lipids, such as PtdIns3P. Cytoplasmic dynein walks towards the minus end of the microtubules. A score of cellular processes is dependent on dynein, such that deficient regulation of the motor has deep consequences in cellular homeostasis, and the identification of new adapters is of broad interest, both basic and, potentially, clinical.
Dynein adaptors usually stabilize the binding of dynactin to dynein using coiled-coil regions to longitudinally embrace dynactin, holding it to the elongated dynein cap of the super-complex. Not only do they adapt cargo but additionally increase the processivity and speed of the motor. In this manuscript, Julie and collaborators present evidence that a protein denoted kazrin, which is involved in a variety of processes, is actually an adaptor connecting endosome domains specialized in recycling cargo back to the surface of the cell by way of the RAB11 perinuclear recycling endosome. The topic is important, experiments have been carefully conducted and well controlled and display items faithfully guide readers through the main findings. However, I feel that the evidence that kazrin is a dynein adaptor is somewhat thin and that it could be improved with relatively little additional work. The manuscript would also benefit from better integration of the conclusions in the current state of the art in the dynein field.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In the current study, Mondoloni and colleagues investigate the neural correlates contributing to nicotine aversion and its alteration following chronic nicotine exposure. The question asked is important to the field of individual vulnerability to drug addiction and has translational significance. First, the authors identify individual nicotine consumption profiles across isogenic mice. Further, they employed in vivo and ex vivo physiological approaches to defining how antiparticle nuclei (IPn) neuronal response to nicotine is associated with nicotine avoidance. Additionally, the authors determine that chronic nicotine exposure impairs IPn neuronal normal response to nicotine, thus contributing to higher amounts of nicotine consumption. Finally, they used transgenic and viral-mediated gene expression approaches to establish a causal link between b4 nicotine receptor function and nicotine avoidance processes.
The manuscript and experimental strategy are well designed and executed; the current dataset requires supplemental analyses and details to exclude possible alternatives. Overall, the results are exciting and provide helpful information to the field of drug addiction research, individual vulnerability to drug addiction, and neuronal physiology. Below are some comments aiming to help the authors improve this interesting study.
1. The authors used a two-bottle choice behavioral paradigm to investigate the neurophysiological substrate contributing to nicotine avoidance behaviors. While the data set supporting the author's interpretation is compelling and the experiments are well-conducted, a few supplemental control analyses will strengthen the current manuscript.<br /> a. The bitter taste of nicotine might generate confounds in the data interpretation: are the mice avoiding the bitterness or the nicotine-induced physiological effect? To address this question, the authors mixed nicotine with saccharine, thus covering the bitterness of nicotine. Additionally, the authors show that all the mice exposed to quinine avoid it, and in comparison, the N-Av don't avoid the bitterness of the nicotine-saccharine solution. Yet it is unclear if Av and N-Av have different taste discrimination capacities and if such taste discrimination capacities drive the N-Av to consume less nicotine. Would Av and N-Av mice avoid quinine differently after the 20-day nicotine paradigm? Would the authors observe individual nicotine drinking behaviors if nicotine/quinine vs. quinine were offered to the mice?<br /> b. Metabolic variabilities amongst isogenic mice have been observed. Thus, while the mice consume different amounts of nicotine, changes in metabolic processes, thus blood nicotine concentrations, could explain differences in nicotine consumption and neurophysiology across individuals. The authors should control if the blood concentration of nicotine metabolites between N-Av and Av are similar when consuming identical amounts of nicotine (50ug/ml), different amounts (200ug/ml), and in response to an acute injection of a fixed nicotine quantity.
2. Av mice exposed to nicotine_200ug/ml display minimal nicotine_50ug/ml consumption, yet would Av mice restore a percent nicotine consumption >20 when exposed to a more extended session at 50ug/kg? Such a data set will help identify and isolate learned avoidance processes from dose-dependent avoidance behaviors.
3. The author should further investigate the basal properties of IPn neuron in vivo firing rate activity recorded and establish if their spontaneous activity determines their nicotine responses in vivo, such as firing rate, ISI, tonic, or phasic patterns. These analyses will provide helpful information to the neurophysiologist investigating the function of IPn neurons and will also inform how chronic nicotine exposure shapes the IPn neurophysiological properties.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors successfully show that how EPAC and PKCε work together to recruit presynaptic proteins for neurotransmitter release instead of synaptic vesicle formation since the absence of EPAC and PKCε does not affect the number of synaptic vesicles. In addition, the data clearly demonstrate that EPAC and PKCε function specifically at the presynaptic terminals and thus is required for induction of presynaptic LTP. Their suggested EPAC- PKCε module is also essential for proper cerebellar motor performance and motor learning.
Furthermore, the order of data analysis perfectly matches the logical explanation of the entire story. The authors first prove that EPAC and PKCε, together with RIM1a, are necessary for neurotransmitter release at the presynaptic terminal. Then, by using specific knockdown mice of presynaptic granule cells, both proteins contribute to the release of synaptic vesicles in that only the frequencies of EPSC have changed. In addition, presynaptic LTP is only induced with the presence of EPAC and PKCε, highlighting the important role of the EPAC- PKCε module. Ultimately, the impact of EPAC and PKCε is shown by conducting the behavior tasks including OKR, VOR, and VVOR.
The authors suggest the missing link between EPAC and RIM1 is PKCε. Phosphorylation of RIM1 by PKCε is a novel signaling cascade found in this paper. The authors' data from the heterologous expression system and cerebellar granule cell-specific PKCε KO mice indicate that PKCε can regulate RIM1Threonine phosphorylation.<br /> The EPAC-PKCε unit is essential to both presynaptic neurotransmitter release and presynaptic LTP in parallel fiber-Purkinje cell synapse. Future work is necessary to dissect which is responsible for cerebellar motor performance and motor learning.
The study provides the necessity of exploring the new part of the motor learning circuit since the significant focus of cerebellar motor learning has been only confined to postsynaptic plasticity. Generally, postsynaptic plasticity is affected by the presynaptic properties, such as presynaptic vesicle release and recycling of neurotransmitters at the synapse. Also, the presynaptic terminal, which can be referred to as an inducing force of the postsynaptic plasticity, does not merely release the neurotransmitters at a constant rate; they also change as a result of incoming stimuli. Such change is called presynaptic plasticity. Therefore, it should be further scrutinized how presynaptic plasticity is conducted and determined.
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Local file Local file
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2.10-2 Theorem (Completeness)
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2.9-2 Lemma· (Zero vector)
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2.7-2 Lemma (Norm).
operator norm is actually a type of norm. Linear operators as homomorphism between the vector spaces are indeed a vector space itself. See here.
The properties of the operator norm basically interits the properties from the normed vector space. This is direct from the definition. However, these results are only for the bounded linear operators.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors sought to define the molecular structure of autoinhibited Kinesin-1, which is the major kinesin providing plus-end directed transport on microtubules. The paper reports a structural model of full-length kinesin-1 which builds on the known folded conformation of kinesin-1 and describes its autoinhibitory mechanism using cryo-EM, alphafold structural predictions, cross-linking and mass spectrometry. The authors study the conformation of dimeric Kinesin Heavy Chain (KHC) and tetrameric KHC bound to the Kinesin Light Chains (KLCs), where KLC stabilize the autoinhibited conformation. The combination of these various approaches leads to an integrated molecular model of autoinhibited Kinesin-1. Until now, there was some debate over the role of the small coiled coil 3 (a and b) and where the hinge region of Kinesin-1. The authors resolve this question and present data indicating the hinge is between cc3a and cc3b.
In some places the absence of crosslinks is reported as a lack of interaction, however it could also be that there are no residues that can be crosslinked in this region. The distance is also not reported in the figures so we do not know how valid these model are. For example for TRAP binding to KHC, there are not many crosslinks but it is not clear if there was an issue with the complex assembly or crosslinking reaction-as there is no EM data of this complex. There is also a structural model of KHC and KLC (Fig 4) where the domains are too far apart for the crosslinks to be allowed, raising a question about whether that model is correct or not. The structural data are supported by single molecule motility assays with various mutants of Kinesin-1, which greatly help characterising the domains functionally.
Overall there are some interesting novel data on the autoinhibitory mechanism of Kinesin-1, with well performed and analyzed data with KLC and TRAP. The topic and paper will be of interest to many.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
To date, only a handful of studies have addressed the importance of AGS3, a paralog of the relatively well-characterized spindle orientation factor LGN. The authors now show that AGS3 acts as a negative regulator of LGN and propose that this activity could work through competition for binding partner(s). Remarkably, regulation is temporally restricted in such a way that the conserved role played by LGN in metaphase spindle orientation is unaffected. Instead, AGS3 regulates a post-metaphase function for LGN, namely Telophase Correction.
The article is well-written, the experiments are performed at a high level, and the claims are generally supported by the data. Two main points of confusion are raised in the current version. 1) The authors show that AGS3 regulates cortical localization of LGN, but would need to clarify how LGN is being affected. 2) The authors propose in the discussion that AGS3 might exert its regulatory effect through competition for NuMA, an important binding partner for LGN, but would need to clarify how and why NuMA would be involved in Telophase Correction.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript by Walker et al describes an elegant study that synergizes our knowledge of virulence gene regulation of Vibrio cholerae. The work brings a new element of regulation for CRP, notably that CRP and the high density regulator HapR co-occupy the same site on the DNA but modeling predicts they occupy different faces of the DNA. The DNA binding and structural modeling work is nicely conducted and data of co-occupation are convincing. The work could benefit from doing a better job in the manuscript preparation to integrate the findings into our current state of knowledge of HapR and CRP regulated genes and to elevate the impact of the work to address how bacteria are responding to the nutritional environment. Importantly, the focus of the work is heavily based on the impact of use of GlcNAc as a carbon source when bacteria bind to chitin in the environment, but absent the impact during infection when CRP and HapR have known roles. Further, the impact on biological events controlled by HapR integration with the utilization of carbon sources (including biofilm formation) is not explored. The rigor and reproducibility of the work needs to be better conveyed.
Specific comments to address:
1) Abstract. A comment on the impact of this work should be included in the last sentence. Specifically, how the integration of CRP with QS for gene expression under specific environments impacts the lifestyle of Vc is needed. The discussion includes comments regarding the impact of CRP regulation as a sensor of carbon source and nutrition and these could be quickly summarized as part of the abstract.<br /> 2) Line 74. This paper examines the overlap of HapR with CRP, but ignores entirely AphA. HapR is repressed by Qrrs (downstream of LuxO-P) while AphA is activated by Qrrs. WithLuxO activating AphA, it has a significant sized "regulon" of genes turned on at low density. It seems reasonable that there is a possibility of overlap also between CRP and AphA. While doing an AphA CHIP-seq is likely outside the scope of this work, some bioinformatic or simply a visual analysis of the promoters known AphA regulated genes would be interest to comment on with speculation in the discussion and/or supplement.<br /> 3) Line 100. Accordingly with the above statement, the focus here on HapR indicates that the focus is on gene expression via LuxO and HapR, at high density. Thus the sentence should read "we sought to map the binding of LuxO and HapR of V. cholerae genome at high density".<br /> 4) Line 109. The identification of minor LuxO binding site in the intergenic region between VC1142 and VC1143 raises whether there may be a previously unrecognized sRNA here. As another panel in figure S1, can you provide a map of the intergenic region showing the start codons and putative -10 to -35 sites. Is there room here for an sRNA? Is there one known from the many sRNA predictions / identifications previously done? Some additional analysis would be helpful.<br /> 5) Line 117. This sentence states that the CHIP seq analysis in this study includes previously identified HapR regulated genes, but does not reveal that many known HapR regulated genes are absent from Table 1 and thus were missed in this study. Of 24 HapR regulated investigated by Tsou et al, only 1 is found in Table 1 of this study. A few are commented in the discussion and Figure S7. It might be useful to add a Venn Diagram to Figure 1 (and list table in supplement) for results of Tsou et al, Waters et al, Lin et al, and Nielson et al and any others). A major question is whether the trend found here for genes identified by CHIP-seq in this study hold up across the entire HapR regulon. There should also be comments in the discussion on perhaps how different methods (including growth state and carbon sources of media) may have impacted the complexity of the regulon identified by the different authors and different methods.<br /> 6) The transcription data are generally well performed. In all figures, add comments to the figure legends that the experiments are representative gels from n=# (the number of replicate experiments for the gel based assays). Statements to the rigor of the work are currently missing.<br /> 7) Line 357-360. The demonstration of lack of growth on MurNAc is a nice for the impact of the work. However, more detailed comments are needed for M9 plus glucose for the uninformed reader to be reminded that growth in glucose is also impaired due to lack of cAMP in glucose replete conditions and thus minimal CRP is active. But why is this now dependent of hapR? A reminder also that in LB oligopeptides from tryptone are the main carbon source and thus CRP would be active.<br /> 8) A great final experiment to demonstrate the model would have been to show co-localization of the promoter by CRP and HapR from bacteria grown in LB media but not in LB+glucose or in M9+glycerol and M9+MurNAc but not M9+glucose. This would enhance the model by linking more directly to the carbon sources (currently only indirect via growth curves)<br /> 9) Discussion. Comments and model focus heavily on GlcNAc-6P but HapR has a regulator role also during late infection (high density). How does CRP co-operativity impact during the in vivo conditions? Does the Biphasic role of CRP play a role here (PMID: 20862321)?
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Reviewer #2 (Public Review):
DNA gyrase is an essential enzyme in bacteria that regulates DNA topology and has the unique property to introduce negative supercoils into DNA. This enzyme contains 2 subunits GyrA and GyrB, which forms an A2B2 heterotetramer that associates with DNA and hydrolyzes ATP. The molecular structure of the A2B2 assembly is composed of 3 dimeric interfaces, called gates, which allow the cleavage and transport of DNA double stranded molecules through the gates, in order to perform DNA topology simplification.<br /> The article by Germe et al. questions the existence and possible mechanism for subunit exchange in the bacterial DNA gyrase complex.
The complexes are purified as a dimer of GyrA and a fusion of GyrB and GyrA (GyrBA), encoded by different plasmids, to allow the introduction of targeted mutations on one side only of the complex. The conclusion drawn by the authors is that subunit exchange does happen, favored by DNA binding and wrapping. They propose that the accumulation of gyrase in higher-order oligomers can favor rapid subunit exchange between two active gyrase complexes brought into proximity.<br /> The authors are also debating the conclusions of a previous article by Gubaev, Weidlich et al 2016 (https://doi.org/10.1093/nar/gkw740). Gubaev et al. originally used this strategy of complex reconstitution to propose a nicking-closing mechanism for the introduction of negative supercoils by DNA gyrase, an alternative mechanism that precludes DNA strand passage, previously established in the field. Germe et al. incriminate in this earlier study the potential subunit swapping of the recombinant protein with the endogenous enzyme, that would be responsible for the detected negative supercoiling activity.
Accordingly, the authors also conclude that they cannot completely exclude the presence of endogenous subunits in their samples as well.
Strengths
The mix of gyrase subunits is plausible, this mechanism has been suggested by Ideka et al, 2004 and also for the human Top2 isoforms with the formation of Top2a/Top2b hybrids being identified in HeLa cells (doi: 10.1073/pnas.93.16.8288).<br /> Germe et al have used extensive and solid biochemical experiments, together with thorough experimental controls, involving :<br /> - the purification of gyrase subunits including mutants with domain deletion, subunit fusion or point mutations.<br /> - DNA relaxation, cleavage and supercoiling assays<br /> - biophysical characterization in solution (size exclusion chromatography, mass photometry, mass spectrometry)
Together the combination of experimental approaches provides solid evidence for subunit swapping in gyrase in vitro, despite the technical limitations of standard biochemistry applied to such a complex macromolecule.
Weaknesses
The conclusions of this study could be strengthened by in vivo data to identify subunit swapping in the bacteria, as proposed by Ideka et al, 2004. Indeed, if shown in vivo, together with this biochemical evidence, this mechanism could have a substantial impact on our understanding of bacterial physiology and resistance to drugs.
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Reviewer #2 (Public Review):
I believe the authors succeeded in finding neural evidence of reactivation during REM sleep. This is their main claim, and I applaud them for that. I also applaud their efforts to explore their data beyond this claim, and I think they included appropriate controls in their experimental design. However, I found other aspects of the paper to be unclear or lacking in support. I include major and medium-level comments:
Major comments, grouped by theme with specifics below:<br /> Theta.<br /> Overall assessment: the theta effects are either over-emphasized or unclear. Please either remove the high/low theta effects or provide a better justification for why they are insightful.
Lines ~ 115-121: Please include the statistics for low-theta power trials. Also, without a significant difference between high- and low-theta power trials, it is unclear why this analysis is being featured. Does theta actually matter for classification accuracy?
Lines 123-128: What ARE the important bands for classification? I understand the point about it overlapping in time with the classification window without being discriminative between the conditions, but it still is not clear why theta is being featured given the non-significant differences between high/low theta and the lack of its involvement in classification. REM sleep is high in theta, but other than that, I do not understand the focus given this lack of empirical support for its relevance.
Line 232-233: "8). In our data, trials with higher theta power show greater evidence of memory reactivation." Please do not use this language without a difference between high and low theta trials. You can say there was significance using high theta power and not with low theta power, but without the contrast, you cannot say this.
Physiology / Figure 2.<br /> Overall assessment: It would be helpful to include more physiological data.
It would be nice, either in Figure 2 or in the supplement, to see the raw EEG traces in these conditions. These would be especially instructive because, with NREM TMR, the ERPs seem to take a stereotypical pattern that begins with a clear influence of slow oscillations (e.g., in Cairney et al., 2018), and it would be helpful to show the contrast here in REM. Also, please expand the classification window beyond 1 s for wake and 1.4 s for sleep. It seems the wake axis stops at 1 s and it would be instructive to know how long that lasts beyond 1 s. The sleep signal should also go longer. I suggest plotting it for at least 5 seconds, considering prior investigations (Cairney et al., 2018; Schreiner et al., 2018; Wang et al., 2019) found evidence of reactivation lasting beyond 1.4 s.
Temporal compression/dilation.<br /> Overall assessment: This could be cut from the paper. If the authors disagree, I am curious how they think it adds novel insight.
Line 179 section: In my opinion, this does not show evidence for compression or dilation. If anything, it argues that reactivation unfolds on a similar scale, as the numbers are clustered around 1. I suggest the authors scrap this analysis, as I do not believe it supports any main point of their paper. If they do decide to keep it, they should expand the window of dilation beyond 1.4 in Figure 3B (why cut off the graph at a data point that is still significant?). And they should later emphasize that the main conclusion, if any, is that the scales are similar.
Line 207 section on the temporal structure of reactivation, 1st paragraph: Once again, in my opinion, this whole concept is not worth mentioning here, as there is not really any relevant data in the paper that speaks to this concept.
Behavioral effects.<br /> Overall assessment: Please provide additional analyses and discussion.
Lines 171-178: Nice correlation! Was there any correlation between reactivation evidence and pre-sleep performance? If so, could the authors show those data, and also test whether this relationship holds while covarying our pre-sleep performance? The logic is that intact reactivation may rely on intact pre-sleep performance; conversely, there could be an inverse relationship if sleep reactivation is greater for initially weaker traces, as some have argued (e.g., Schapiro et al., 2018). This analysis will either strengthen their conclusion or change it -- either outcome is good.
Unlike Schönauer et al. (2017), they found a strong correspondence between REM reactivation and memory improvement across sleep; however, there was no benefit of TMR cues overall. These two results in tandem are puzzling. Could the authors discuss this more? What does it mean to have the correlation without the overall effect? Or else, is there anything else that may drive the individual differences they allude to in the Discussion?
Medium-level comments<br /> Lines 63-65: "We used two sequences and replayed only one of them in sleep. For control, we also included an adaptation night in which participants slept in the lab, and the same tones that would later be played during the experimental night were played."
I believe the authors could make a stronger point here: their design allowed them to show that they are not simply decoding SOUNDS but actual memories. The null finding on the adaptation night is definitely helpful in ruling this possibility out.
Lines 129-141: Does reactivation evidence go down (like in their prior study, Belal et al., 2018)? All they report is theta activity rather than classification evidence. Also, I am unclear why the Wilcoxon comparison was performed rather than a simple correlation in theta activity across TMR cues (though again, it makes more sense to me to investigate reactivation evidence across TMR cues instead).
Line 201: It seems unclear whether they should call this "wake-like activity" when the classifier involved training on sleep first and then showing it could decode wake rather than vice versa. I agree with the author's logic that wake signals that are specific to wake will be unhelpful during sleep, but I am not sure "wake-like" fits here. I'm not going to belabor this point, but I do encourage the authors to think deeply about whether this is truly the term that fits.
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Reviewer #2 (Public Review):
The authors reexamine the effects of depth on crowding, using a clever display that presents at three depths at once, and find that placing the target or flanker at far depth greatly increases crowding, contrary to what might have been expected by prior work with small depth differences. These stimuli avoid creating conflicting cues to depth and are thus the most relevant to viewing in daily life, indicating more crowding than was expected.
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Reviewer #2 (Public Review):
This study was designed to study the cortical response to violations in auditory temporal sequences during wakefulness and sleep. To this end, the study had three levels of temporal sequence, a regular temporal sequence, an auditory tone that was yoked to the cardiac signal, and an irregular tone. The authors show significant EEG differences to an omitted tone when the auditory tone was predictable both during wakefulness and sleep.
The authors analyze the ERP to the omitted tone as well as when aligned to the R-peak of the HEP. The analysis was comprehensive and the effects reported align with the interpretation given. Of particular interest was the fact that a deceleration of the heart rate was present for omissions when the auditory tone was yoked to the R-peak (synch) in all stages of wakefulness and sleep.
However, one weakness was the rationale for the current study and how the results link to current theoretical frameworks for the role of interoception in perception and cognition. This was in contrast to the clear background and explanation to study the response to omissions for a predictable auditory sequence in wakefulness and sleep. It was unclear why the authors selected the cardiac signal to yoke their auditory stimuli. What is the specific motivation for the cardiac signal rather than the respiratory signal? This was not clear.
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Reviewer #2 (Public Review):
The authors tackled a longstanding question for brain evolution: if the brain regions change based on functional constraints or developmental constraints.
The strength of this study is that the authors introduced an automated method for brain segmentation based on the zebrafish tool, which is a highly advanced technology. They also performed the volume and landmark-based shape analyses in a surface, cave and their F1 and F2 hybrid, highlighting genetic regulations, and revealed 3 genetically correlating clusters of brain regions, which are brand new as far as I know. This study needs intense effort, fine skills to conduct, and intellectual efforts to summarize the vast dataset. I simply admire how the authors achieve their study at this level.
The weakness of this study is that the method/approach used in this study is difficult to test the functional constraint hypothesis although the authors nicely tested the developmental constraint hypothesis, which was highlighted in their correlation studies (volumetric and shape: Fig 4 and 5). I am also a little concerned with the accuracy of the automated segmentation algorithm shown in Figure 1-figure supplement 2. The original zebrafish paper (CobraZ) showed a similar accuracy (cross-correlation as 80%). If this level of accuracy is accepted in the field, I am OK with it.<br /> Their data support the conclusion 'brain-wide evolution occurs in distinct developmental modules' because of their correlation study. However, I am not so positive at the point that one of two central hypotheses were directly tested in this study: the functional constraint hypothesis - to test it, for example, the authors need to address the functional connectivities (calcium imaging, etc) and then test if the correlation between calcium-transients and the size/shape of each pair of brain regions.
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Reviewer #2 (Public Review):
Jangir et al test the hypothesis that resistance to the antimicrobial peptide (AMP) colistin can simultaneously increase resistance to other AMPS with related modes of action. Because AMPS comprise part of innate immunity, their central concern is that colistin resistance may compromise host defenses and thereby increase bacterial virulence. Their results show that MCR-1, whether expressed from naturally circulating or synthetic plasmids, can increase the MIC to AMPS from humans, pigs, and chickens, and impart fitness benefits at sub-MIC concentrations. In addition, they find that MCR-1-containing strains have increased survival in human plasma and are more lethal in an insect infection model.
The conclusions of the paper are generally well supported by the results, but some aspects could be clearer and better defended with a few small additional experiments.
Strengths:<br /> Using both synthetic and natural plasmids makes it possible to cleanly separate the effects of MCR-1 from the effects of other plasmid-borne genes or plasmid copy numbers. This helps confirm the causal role of MCR-1 on altered AMP susceptibility.
Testing the survival of transformed isolates in human serum and in insects points to relevance in the more immunologically complex host environment where cells are exposed to a suite of factors that reduce bacterial survival.
Weaknesses/suggestions:<br /> Although increases in MIC are evident for different AMPS, the effects are generally modest. To address this, it might be helpful to use pairwise competition assays, as in Figure 1, to establish that even small changes to MIC are associated with clear selective benefits. This would be especially helpful in assays with human serum and in Galleria where the concentrations of AMPS or other immune components are unknown.
Assays using human serum are interesting but challenging to interpret given the diverse causes of bacterial killing, including complement. Although this was partly addressed in Supplementary Figure 6, I found the predictions of these experiments unclear. First, I think these experiments are too central to be relegated to the supplemental materials; they belong in the main text. Secondly, it is important to explicitly spell out the expectations of using heat-killed serum (which will degrade any heat-labile components) or complement-deficient serum. It should be clearer under which conditions MCR-1-containing strains are predicted to do better or worse than controls.
Galleria is a useful infection model for virulence, but it is unclear what drives differences between strains. First, bacterial numbers aren't measured in this assay, so it isn't known if increased virulence is due to increased bacterial growth or decreased bacterial clearance. As above, I think these assays would be stronger using the competition-based approach in Figure 1. This would indicate bacterial numbers through time and directly show the selective benefit associated with MCR-1. Second, it would be useful to elaborate on why MCR-1 increases virulence, especially any known similarities between Galleria AMPS and those tested in Figures 1 and 2. Overall, it would help if Galleria were less of a black box.
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Reviewer #2 (Public Review):
The study by Yanase et al. investigated the details of the 3D architecture of Leishmania haptomonad promastigote's adhesion to the midgut of the insect vector. The authors generated a dataset of images that reveal intricate details of the formed adhesion plaque and expanded the study with in vitro alternatives for the exploration of how Leishmania promastigotes strong adhesion by hemidesmosomes to surfaces can happen and be maintained. They show with unprecedented detail the ultrastructure of the attachment plaque. The in vitro dataset of the paper adds to the specific literature important details on how to explore micro/nanostructures involved in an important attachment step for this eukaryotic parasite. However, the in vitro data should be reconsidered in its discussion and conclusions as it does not support direct comparison with in vivo Leishmania forms as pictured by the authors. In general, the dataset presented in this manuscript adds valuable data and resources for the study of Leishmania promastigotes to surfaces, especially to the thoracic midgut parts of its insect vector.
The dataset of this paper is well-collected and robust, but some aspects of image analysis need to be clarified and extended. Also, the in vitro data from the manuscript will benefit from an extensive adjustment in its discussion. Points to focus on:
1) The haptomonad promastigote is indeed a possible critical form for transmission, but it lacks formal demonstration still in all literature available. This should not be claimed without proper formal demonstration.
2) Literature available and cited in this manuscript regarding in vitro adhesion of culture Leishmania promastigotes does not provide direct evidence for haptomonad differentiation. Haptomonads are still a largely unknown promastigote form with no defined ontogeny. With that, to propose an in vitro haptomonad differentiation protocol, more detailed direct evidence of in vivo haptomonads will be necessary. The in vitro experiments available show how cultured promastigotes attach to surfaces. Detailed studies in vivo will be needed still to attribute the findings in vitro to haptomonads.
3) This manuscript will benefit by having a detailed description of how to analyze and get to the 3D models presented. This has a strong potential for usage beyond the Leishmania/sand fly field. Statistics should be made available with ease across the manuscript and with a dedicated section on methods.
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Reviewer #2 (Public Review):
The manuscript by Sampaio and colleagues utilizes an elegant and delicate approach to manipulate fluid dynamics in zebrafish Kupffer's vesicle (KV) to answer a long-standing question in the field - is it fluid movement or something in the fluid that governs the break in symmetry?
The researchers extract fluid from KV at different times during somitogenesis and find this procedure results in left-right organ defects when fluid is removed from the 3 to 5 somite stage, peaking at 5 somites. The effect on left-right patterning by this manipulation is not significant from the 6 somite stage onward. This technique is non-trivial and the researchers have used it with great effect.
Fluid extraction in this sensitive time window (3-5 somites) did not affect cilia number, length, or distribution within KV suggesting the effect on left-right patterning is due to disruption of the fluid. There is a clear effect of the manipulation on dand5 RNA asymmetry as expected. Manipulated embryos that developed left-right defects also showed a decrease in angular velocity of particle movement in the anterior LRO. Increasing the viscosity of the fluid in KV with methylcellulose also results in left-right patterning defects. Taken together, these results are in strong support of fluid movement and detection being important in breaking symmetry in a ciliated left-right organizer. They also argue against the idea that there are signals in the fluid that are being moved asymmetrically to signal to the "left" to break the symmetry. Importantly, they help set a time window when fluid flow is critical for this process.
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Reviewer #2 (Public Review):
The authors conducted a wide-ranging series of experiments which lead to the conclusion that NBR1 is involved in the clearance of photodamaged chloroplasts. It is a novel finding because the role of NBR1 in this process was never documented. Notably, the NBR1-mediated clearance is only one of the several possible mechanisms responsible for chloroplast turnover. It is not surprising, considering that the nbr1 mutants are viable. The work is arranged very well. The rationale of the subsequent experiments is logically justified and the outcomes and followed by clear conclusions. In consequence, the authors managed not only to observe the association of NBR1 with the chloroplasts but they threw some light on the corresponding mechanisms. The manuscript contains numerous high-quality images from a confocal microscope and from a transmission electron microscope. All images are accompanied by statistical analysis of the respective microscopic observations, which greatly improves the credibility of the conclusions. Shortly, the authors demonstrated that NBR1 decorates not only the exterior but also the interior of damaged chloroplasts in an ATG7-independent way. Next, they establish that NBR1 and ATG8 are recruited to different populations of damaged chloroplasts, and they document differences in chloroplasts turnover, differences in chlorophyll abundance and chlorophyll photochemical properties, as well as differences in the total proteome of the nbr1 mutant in comparison to the wild type and atg7 mutant in two light regimes (low light and high light). Finally, they exclude the requirement for the known E3 ligases PUB4 and SP1 for NBR1-mediated degradation and show that the NBR1 internalization relies rather on the chloroplastic membrane rupture than on the TIC-TOC-dependent processes. In summary, the authors postulate that NBR1-mediated chloroplast clearance is a novel, not yet described mechanism and summarize it in a clear diagram.
The work is interesting, the figures are convincing and the conclusions are justified by the results. It provides novel data on the function of selective autophagy receptors NBR1 in plant cells, however, it also leaves the reader with some unanswered questions. The most important is the relative contribution of each of the chloroplast's degradation routes to the turnover of these organelles in different stresses, light regimes, plant growth stages, etc. This is a difficult problem because the mutations in relevant genes have pleiotropic effects and it is difficult to separate the functions of the individual turnover routes. For example, the defects in core autophagy genes (like the atg7 mutant used in this study) result in an increased level of NBR1. These issues are not sufficiently addressed in the discussion.
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Reviewer #2 (Public Review):
In this work Xia et al have generated CRISPR resources for genome-wide gain-of-function genetic perturbation in the Drosophila genome and have used them to identify novel genes that cause Rapamycin resistance in Drosophila cells. To do so, they have used the SAM system, already established to work well in flies (Jia et al., PNAS 2018). 3 of these candidate genes they discovered in the screen, were further characterized to study how they affect the mTOR pathway leading to Rapamycin resistance. Since genome-wide libraries for GOF studies do not exist for Drosophila, these resources will be very useful for a wider Drosophila community.
Strengths
1. GOF CRISPR library does not exist currently to be used in Drosophila and hence this is going to be useful for the wider Drosophila community<br /> 2. Authors have used already established and currently the most effective SAM system for gene activation for a genome-wide genetic screen.<br /> 3. From this screen they have found candidate genes overexpression which leads to Rapamycin resistance. They have validated 3 of these genes by multiple methods and have also tried to elucidate the mechanism by which these genes might regulate mTOR signaling and confer resistance to Rapamycin. The authors have shown the strength and usefulness of the resource that they have generated and this resource will be complementary to loss-of-function screens of similar nature.
Weaknesses
1. Authors have taken a number of measures to maintain the integrity of the CRISPRa library, including multiple gRNA targets per gene, 1000 cells per gRNA, and deep sequencing. However, do the authors have an idea of what percentage of the gRNA vectors are functional? Looking at the data they show for the 3 candidate genes, at least half of them are not functional, which could be either because of gRNA location or efficiency. Considering this to be an average situation, there might be a large number of genes for which all gRNAs might not function at all. I understand this might be a caveat for all such studies, but an estimate of some kind in discussion might be useful for anyone who might want to use these resources.<br /> 2. As the authors mention that ~32% of genes in Drosophila have transcription start side <1kb apart, off-targeting (neighbouring genes getting activated in addition to the intended gene) will be an issue. To address this, the authors describe one example of genes where although the genes TSS are within one kb of each other, the sgRNA specifically activated only one gene and not the other. However, since following this, authors have generated genome-wide resources keeping 500bp upstream as their benchmark, a large percentage of these 32% genes might have off-targets. It would be useful to know the estimates of off-targeting for such a resource. In addition, have authors looked at the transcripts of genes close to the specific genes they have studied? CG9932 is in close proximity to (although not within the 1 kb range) a few genes including mTOR.
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Reviewer #2 (Public Review):
The authors conduct a structure-function analysis of an uncharacterized gene, DltE, which was found by a genetic screen to be involved in the growth promotion of Drosophila larvae by Lactiplantibacillus plantarum, a bacterium that is consistently associated with Drosophila. They find that DltE is a D-Ala carboxylesterase that removes D-Ala from lipoteichoic acids in the cell envelope and that D-alanylated lipoteichoic acids stimulate Drosophila larval growth. The result that D-Ala LTA stimulates larval growth is compelling, although some minor experimental details to do with biological replicates are not shown and the tracking of bacterial abundances should be addressed to make the conclusions more solid. Additionally, I think the use of the terms "direct" and "symbiotic" is inappropriate in the manuscript, but this can be resolved by removing them or performing additional experiments.
The authors make these claims:<br /> - DltE is not a carboxypeptidase modifying Lp peptidoglycan;<br /> - DltE is a D-Ala esterase acting upon D-Ala-LTA;<br /> - only LTAs but not WTAs are D-alanylated in LpNC8 cell envelopes;<br /> - D-Ala-LTAs, in addition to PG, are direct symbiotic cues supporting<br /> (1) intestinal peptidase expression and<br /> (2) juvenile growth in Drosophila.<br /> I find all of the claims to be well supported by data except the suggestion that these are "direct symbiotic" cues. I think the authors provide the support that D-Ala LTAs are nutritional cues, not symbiotic ones.
Overall, I find the work compelling.
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Reviewer #2 (Public Review):<br /> <br /> MAPKs are key fundamental enzymes and out of the 14 MAPKs, ERK3 and ERK4 remain less studied. The authors have made some interesting discoveries on ERK3, especially in the context of chemotaxis and tumourigenesis previously (Bogucka et al eLife 2020). Here they investigated the role of ERK3 in the control of cell architecture. Loss of ERK3 led to a reduction in the formation of actin-rich protrusions which led the authors logically to look for the activation of RhoGTPases. Intriguingly, they found that ERK3 functioned as a GEF for Cdc42 but not for Rac1. Further, they identified that Rac-WAVE and Arp2/3 were present at endogenous levels in a heteromeric complex in cells. As ERK3-deficient breast epithelial cells exhibit less F-actin content, this has led the authors to check for Arp2/3-dependent events here. By employing a variety of knockdown and complementation approaches, the authors convincingly demonstrate that the kinase activity of ERK3 is not required for the total F-actin content but for the formation of actin-rich protrusions. Finally, loss of ERK3 reduced random cell motility in vitro and in vivo, which was accomplished by intravital imaging of breast cancer cells in mice. Many protein kinases have catalysis-dependent and -independent functions (catalytic activity versus allosteric activity) and here is another example that deserves further investigation and opens new lines of investigation.
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Reviewer #2 (Public Review):
De Filippo et al. investigated the spatiotemporal dynamics of the ripples propagation in the hippocampus of head-fixed mice. By leveraging the LFP and the isolated units of an open dataset of 49 animals with ~6 Neuropixels probes in the longitudinal axis of the hippocampus, they found: first, that stronger ripples (>ninth decile of power) originated in the most septal pole of the hippocampus (medially, anatomically) tend to travel more (M to L) than more lateral ripples (closer to the temporal pole). Second, while strong ripples were mainly local, the authors found that they are most likely to be generated in the temporal pole of the hippocampus, from where they can travel with relatively small attenuation. Finally, they found that strong/septal ripples elicit high spiking activity along the entire mediolateral axis of the hippocampus. Longer/stronger ripples have been proposed to be important in situations with high memory load, and these analyses increase our understanding of their physiology and mechanisms of generation.
The conclusions of this paper are mostly well supported by data, but some aspects of interpretation and data analysis need to be clarified and extended.
1) High amplitude ripples preferentially occur in distal CA1, and ripples can propagate at a higher degree on the proximo-distal than in the septo-temporal axis of the hippocampus (Kumar and Deshmuckh, 2020). Therefore, a proximo-distal bias in the Neuropixel positioning could explain part of the variance the authors report. Authors should consider (or control for) the proximodistal positioning of the electrodes.
2) In my opinion, the dynamics of the ripple-induced spiking activity for the events generated in the medial or lateral section of the hippocampus are very striking, more even considering that only a minority of the detected ripples are strong/long events (less than 5% in a familiar environment, Fernandez-Ruiz et al, 2019), while, according to the authors, majority of the ripples (grouped as 'common' by the authors) travel on the opposite direction (from the lateral section towards the septal pole, figure 2). Moreover, in the 50-120ms window, the most lateral positions (>3500um) seem to be more influenced by the medial ripples than relatively more central electrodes (~3000um). How can the authors explain this? To understand a little bit more how ripple features relate to the spiking dynamics, authors could try to generate heatmaps of the differential spiking between medial and lateral ripples (as they did in Fig. 4D-E) for 'strong' and 'common' ripples, or for local and propagating ripples.
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- Mar 2023
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Reviewer #2 (Public Review):
Lloyd et al examine the relationship between pupil size and fMRI signals in six brain nuclei responsible for providing the four major neuromodulators in the brain: norepinephrine from the locus coeruleus (LC), dopamine from ventral tegmental area (VTA) and substantia nigra, serotonin from the dorsal and median raphe nuclei, and acetylcholine from the cholinergic basal forebrain. Importantly, the authors focus on the relationship between these nuclei in the ascending arousal system (AAS) and the pupil at rest, outside of the context of any task, to determine the extent that small changes in pupil size are predictive of AAS activity.
Very few previous studies have examined this relationship at rest, perhaps in part because of the increased sensitivity required in the absence of event-based averaging. These nuclei are small (especially the LC), and thus are difficult to measure with standard fMRI.
The authors use a number of data collection and processing techniques to increase the sensitivity and precision of their recordings targeted to small ROIs. They find robust correlations between multiple AAS nuclei and pupil size with a time course that is not well captured by a standard hemodynamic response function (HRF).
The latter methodological finding is likely to be useful to the field for future studies focused on extracting useful signals from these nuclei, and the observed relationship between multiple AAS nuclei and the pupil support an emerging consensus from animal research that pupil fluctuations are correlated with neuromodulators besides norepinephrine.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Mansur et al highlight interesting aspects of KLHL40-mediated proteostatic mechanisms in secretion and skeletal muscle development in zebrafish. They propose that KLHL40-mediated ubiquitylation of functional modules in the muscle proteome, particularly membrane traffic components, regulates protein abundance to control development. The authors present solid evidence for the role of KLHL40-mediated ubiquitylation and degradation of the cellular proteome but would benefit from further supporting evidence for their direct consequences on protein secretion.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The availability of large collections of Mycobacterium tuberculosis (Mtb) isolates has enabled many important studies looking to identify mycobacterial genetic polymorphisms associated with anti-tuberculosis (TB) drug resistance, including both classical "resistance-conferring" mutations and novel "resistance-enabling" mutations. Importantly, these studies have expanded our understanding of mycobacterial genetic adaptations undermining chemotherapy, in many cases allowing for improved diagnostic tests and predictions of treatment failure. In this submission, Gao and colleagues adopt a different approach to the problem: although also applying a GWAS-type analysis, they instead attempt to elucidate polymorphisms implicated in poor outcomes of TB patients undergoing treatment for the drug-susceptible disease. Starting with a large dataset comprising 3496 samples with corresponding clinical (host) metadata, the authors generate Mtb whole-genome sequence data for 91 samples obtained from patients with "poor" outcomes and 3105 patients with "good" outcomes. These are used to identify 14 fixed and >230 unfixed mutations that might be associated with "poor" treatment outcomes, a conclusion which they argue is plausible given transcriptional evidence implicating many of the identified genes in the mycobacterial response in vitro to first-line drug exposure and/or hypoxia, both of which are considered relevant to clinical disease. Notably, they also identify a tendency for a greater proportion of "ROS mutational signatures" in unfixed mutations from "poor" outcome samples. Finally, incorporating these observations in a prediction model, the authors observe that the mycobacterial factors aren't adequate on their own but, when combined with key host factors - including patient age, sex, and duration of diagnostic delay (which have stronger predictive value) - they enhance predictive capacity. In summary, this paper reports a novel approach yielding observations that offer tantalizing insight into the mycobacterial factors which might influence TB treatment outcomes independent of drug resistance, however, the following must be considered:
(i) The manuscript provides little to no detail about how the samples were obtained, other than the fact that they comprise "pre-treatment" samples: are they all sputum samples? Were they induced? Similarly, no information is provided about sample propagation: were the samples cultured to achieve sufficient biomass for whole-genome sequencing? If so, in what growth media, for how long, and how many passages? Were all samples treated identically? And were they plated to single colonies - or are the "isolates" referred to throughout the manuscript actually heterogenous populations of potentially different Mtb clones obtained - and propagated - as a mixed sample? This information is critical given the potential that the identified polymorphisms - both fixed and (perhaps even more so) unfixed - might have arisen as a consequence of in vitro (laboratory) manipulation under standard aerobic conditions.
(ii) A key question that arises from this study (and others like it) is whether causation has been adequately established. Ideally, the Mtb genotypes contained within samples obtained pre-treatment should be compared with samples obtained from the same patients following treatment - that is, when the "poor" outcome was manifest. The expectation is that the polymorphisms identified prior to initiation of therapy - especially the 14 fixed mutations - should be evident (even dominant) at the later stage when therapy failed (or at the subsequent presentation in cases of relapse). Recognizing that this is not easily accomplished, though, it seems fair to suggest that the perceived relevance of the identified mutations would be strengthened if the authors were able to provide any other evidence - perhaps from studies of drug-resistant Mtb isolates - supporting their inferred role in undermining frontline treatment.
(iii) Related to the above, the authors make the valid point that their intention here was different from other studies which have deliberately utilized drug-resistant Mtb isolates to identify resistance-conferring and resistance-enabling mutations (such as in the study they cite by Hicks et al). It would be interesting to know, however, if any of the mutations identified in those other studies were also picked up in this work - and, if not, why that might be the case.
(iv) Finally, the analyses presented in this study are heavily dependent on the use of appropriate statistical methods to identify potentially rare genetic polymorphisms. However, as noted for sample processing (see my earlier comment above), there is very little detail provided about the methodology applied. This omission detracts from the interpretation, especially given that the predominance of lineage 2 (which contributes >75% of the isolates, with sublineage 2.3 constituting >50%) risks a lineage-specific association, rather than a more generalizable pathogenicity phenotype. Similarly, the heavy skew in the numbers of "good" (3105 samples) versus "poor" (91 samples) collections (approximately 34x difference in sample size) raises the possibility that mutations identified in the "poor" category might be artificially over-represented. More clarity in detailing the statistical methods is required to allay any concerns about the identification of candidate polymorphisms.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Acute lung injury (ALI) and ARDS are major causes of morbidity and mortality in critically ill patients and patients infected with Sars-Cov-2. There are no effective therapies for ALI/ARDS, and the 28-day mortality rate is ~40%. One of the main pathological features of ALI/ARDS is a vascular injury characterized by endothelial dysfunction, inflammation, and in situ thrombosis. Using a murine model of ALI/ARDS triggered by diphtheria toxin (DT) mediated endothelial specific ablation, the authors apply sc-RNA-seq analysis to study how lung cell populations respond to injury and identify two main endothelial subpopulations responsible for regenerating lung vasculature over seven days. The study's implications are exciting as they provide evidence of intrinsic repair mechanisms that could be targeted for vascular regeneration and recovery of lung function in the context of ALI/ARDS. In particular, the apelin pathway rises as a prime therapeutic candidate given its role in coordinating the behavior of general and aerocyte capillary cells in lung vascular repair.
While the results of this study are exciting and novel, it must be recognized that several limitations need to be properly addressed to facilitate the translation of the findings toward medical care. For instance, the animal model used in this study (DT mediated EC ablation) does not fully recapitulate all the pathological hallmarks of ALI/ARDS, the most important of which is that repair proceeds at a very slow pace as a result of multiple factors that are not recapitulated in this made. Since the authors use only one model of ALI/ARDS, it is not entirely clear whether the current findings can be generalized to other models. Since no one model truly recapitulates the complexity of human ALI/ARDS, it is important to use at least two or more models that can narrow genetic and molecular mechanisms fundamental to lung injury and recovery. Another important aspect is the lack of validation in human samples and cells, which could strengthen the conclusions raised by the authors in the discussion. Finally, the authors appropriately emphasize how this study could help efforts to understand Sars-Cov2 mediated ALI/ARDS. Still, no studies explore any overlap with currently available Omics data from COVID lungs.
Despite these weaknesses, this study is the first to apply rigorous scRNA-seq analysis to this unique model of ALI/ARDS. It also provides data to support the importance of the two newly discovered endothelial cell subpopulations (gCap and aCap) in lung repair and regeneration, which hold the potential to offer unique mechanistic insights into the genetic and molecular mechanisms responsible for vascular repair and offers the opportunity to consider apelin based therapeutic approaches to treat ALI/ARDS. In conclusion, this study is expected to contribute to our lung biology understanding greatly. It provides the research community with novel resources and tools that greatly aid efforts to understand ALI/ARDS and identify therapeutics to treat this devastating disease.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors utilized a label-free LC-MS/MS analysis in formalin-fixed paraffin-embedded (FFPE) tumors from 143 LNM-negative and 78 LNM-positive patients with T1 CRC to identify protein biomarkers to determine LNM in T1 CRC.
The authors used a fair number of clinical samples for the proteomics investigation. The experimental design is reasonable, and the statistical methods used in this manuscript are solid.
The authors largely achieved their aims and the results supported their conclusion. The method used in this proteomic study can also be used for the proteomics analysis of other cancer types to identify diagnostic and prognostic biomarkers. In addition, the 9 marker panel has a potential clinical diagnosis practice in determining LNM in T1 CRC.
Nevertheless, the authors need to justify their standards in selecting the biomarkers. For example, a p-value cut-off of 0.1 is not a usual criterion in similar proteomic studies. In addition, an identification frequency of 30% in patients seems not preferable for biomarker identification. The authors also need to justify the definition of fold change in the three subtypes with Kruskal-Walli's test. The authors need to describe more details on how they identified the 13 proteins from a 55-protein database. In addition, what is the connection between the final 9 proteins and the 19 proteins? What is the criterion to select 5 proteins for IHC validation from the 9 proteins?
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The paper by Laurenz Lammer and colleagues used cohort data to investigate the cross-sectional and longitudinal association between loneliness and brain structure and cognitive function. The main finding was that baseline social isolation and change in social isolation were associated with smaller hippocampus volumes, reduced cortical thickness, and poorer cognitive function. Given that more and more people feel lonely nowadays (e.g., due to the pandemic), the study by Lammer and colleagues addresses a highly relevant health concern of our time.
Significant strengths of the study:
- large cohort;<br /> - the cross-sectional and longitudinal analyses confirmed the findings;<br /> - the study was preregistered;<br /> - the study included men and women;<br /> - analyses were sound and controlled for essential confounders.
The major weaknesses of the study:
- it is unclear whether loneliness causally contributes to brain structure and cognitive function;<br /> - the factors that may cause loneliness are unclear.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Overall, this manuscript provides a thorough characterization of the role of microtubules in the movement of GLUT4 in muscle fibers, and demonstrates the need for an intact microtubule network for GLUT4 responsiveness but only after the initial round of response.<br /> The study poses a very interesting question, rooted in studies in the literature studying the effects of Nocodazole (Noco) and C2-ceramide on GLUT4 traffic in cell systems. It is important to validate or refute predictions from those studies and, largely through this group's work, the quest to examine these questions in isolated muscle fibers and intact muscles as feasible is commendable. The authors develop very interesting imaging approaches to this end, and quantify the results in a convincing and elegant fashion. The system to measure 2-DG uptake and glucose uptake by electrochemical sensing in isolated fibers using the microfluidic pump is very ingenious.<br /> The main conclusion that microtubules are important for GLUT4 proper localization is important and adds mechanistic insight beyond that obtained from work in myoblasts and pre/adipocytes. The observation that microtubules are not engaged in GLUT4 traffic in the first round of insulin action but it is thereafter is also very revealing and should lead to more insights into the first and subsequent rounds of GLUT4 translocation.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Schild et al. investigate the regulation of temporal control during neuroblast migration in the roundworm C. elegans. The authors find that expression of the Wnt pathway receptor Mig1 is regulated early through a specific noncoding conserved intronic element and later through two specific upstream conserved DNA elements. The expression levels of Mig1 in QR.pa cells are further regulated through Ced-3 and pig-1. The variability in the timing of later expression of Mig1 in QR.pa cells through bar-1 or a terminally truncated version of Bar1 was modulated but the mean expression did not change.
The single molecule RNA-FISH data is strong, and this method is sensitive enough to detect differences between different single cells and mutants. The mutants are very precise and straightforward to interpret. An additional strength is that many cells and replicas have been measured. The data analysis is simple.
The proposed model is simple with few intuitive parameters. This makes parameter identification straightforward. The qualitative predictions do make sense and are consistent with most experimental observations.
Overall the manuscript addresses the important question of timing regulation in transcription.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The normally T cell restricted Src family tyrosine kinase Lck is ectopically expressed in most B cell Chronic Lymphocytic Leukemias. This, along with the fact that ectopic expression of other SFKs, such are Fyn and Fgr, are not seen, suggests that Lck may have some unique function, distinct from the endogenous Lyn SFK, that promotes malignant transformation. Using inducible expression in a human B cell lymphoma, the study explores this possibility. Studies reveal no qualitative functional differences in Lck and Lyn that are likely to explain its unique ectopic expression of Lck in CLL.
The strengths of this study include the use of Lentiviral transfer of genes encoding SFKs in conjunction with Doxycycline inducible expression. This allows comparative analysis of acute Lyn and Lck overexpression effects, free of cell resetting artifacts consequent to long term expression of the SFK. Strength is also seen in the authors fluorescent tagging of the SFK so analysis could be gated on ectopic expression level. Strength exists in the authors dissection of SFK effects on early events in the BCR signaling pathway, which reveal the ability of both overexpressed SFKs to drive receptor ITAM tyrosine phosphorylation and initiating BCR signaling. These studies reveal little difference in the function of the SFKs, though it appears that Lck may be less sensitive to phosphatase regulation.
It is unclear from the material and methods whether the overexpressed Lyn is LynA or Lyn B. It appears in the text (lines 130-133) that they overexpress LynB specifically. A recent paper from Tania Freedman (Sci Adv 2022 PMID:35452291) suggests that LynA is more activating whereas LynB is more balanced with an inhibitory bias. The point is that it is important to discuss this because they may not be making a relevant comparison.
If Lck promotes pathophysiology by transduction of a qualitatively unique signal, one would expect that transcriptome analysis should reveal this difference. The authors look for this signal using transcriptome analysis of bulk populations expressing similar levels of SFK. Although differences were seen in the transcriptome, finding were not consistent with a qualitatively unique function. However, bulk transcriptomic analysis may miss important differences. Single cell RNAseq, e.g., by 10x, may have been more incisive because gene expression could have been normalized to SFK expression in individual cells.
Finally, while some interesting differences are seen in the biology of Lyn and Lck, weakness exists in the failure to explore the causality of these differences in driving CLL phenotype. A final thought relevant to this comment. It is a truism that "absence of proof is not proof of absence".
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this work, the authors aimed to understand the ion selectivity mechanism of a plant NRAMP-related aluminum transporter by structural and biochemical characterizations.
The authors successfully identified SiNRAT as a promising candidate for structural and biochemical analyses, showed that SiNRAT transport various divalent cations as well as binding to trivalent cations, determined the cryo-EM structure of SiNRAT, and performed structure-based mutational analysis to identify a potential binding site for metal ions. Unfortunately, the authors failed to show direct evidence of Al3- transport, due to technical problems. Furthermore, the structure of SiNRAT in complex with Al3+ was also not shown.
Despite such weakness, the structural comparison with other NRAMP members with different ion selectivity properties together with the extensive biochemical analyses would support the statement by the authors on a mechanism of ion selectivity for Al3+.
In the discussion section, the authors posed an important question. Considering the weak ion selectivity of SiNRAT over divalent cations, it is still unclear how NRAT proteins can function as an Al3+ transporter in a physiological condition where other divalent cations are also abundant. This would be an important question to be addressed in the related research field in the future.
The methods section is well written and the atomic coordinates and EM map file will be available to the community.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The authors use data from 3 cross-sectional age-stratified serosurveys on Enterovirus D68 from England between 2006 and 2017 to examine the transmission dynamics of this pathogen in this setting. A key public health challenge on EV-D68 has been its implication in outbreaks of acute flaccid myelitis over the past decade, and past circulation patterns and population immunity to this pathogen are not yet well-understood. Towards this end, the authors develop and compare a suite of catalytic models as fitted to this dataset and incorporate different assumptions on how the force of infection varies over time and age. They find high overall EV-D68 seroprevalence as measured by neutralizing antibodies, and detect increased transmission during this time period as measured by the annual probability of infection and basic reproduction number. Interestingly, their data indicate very high seroprevalence in the youngest children (1 year-olds), and to accommodate this observation, the authors separate the force of infection in this age class from the other groups. They then reconstruct the historical patterns of EV-D68 circulation using their models and conclude that, while the serologic data suggest that transmissibility has increased between serosurvey rounds, additional factors not accounted for here (e.g., changes in pathogenicity) are likely necessary to explain the recent emergence of AFM outbreaks, particularly given the broader age-profile of reported AFM cases. The Discussion mentions important current unknowns on the biological interpretation of EV-D68 neutralizing antibody titers for protection against infection and disease. The analysis is rigorous and the conclusions are well-supported, but a few aspects of the work need to be clarified and extended, detailed below:
1) Due to the lack of a clear single cut-point for seropositivity on this assay, the authors sensibly present results for two cut-points in the main text (1:16 and 1:64). While some differences that stem from using different cut-points are fully expected (i.e., seroprevalence being higher using the less stringent cut-point), differences that are less expected should be further discussed. For instance, it was not clear in Figure 2 why the annual probability of infection decreased after 2010 using the 1:64 cut-point, while it continued to increase using the 1:16 cut-point. It would also be helpful to explain why overall seroprevalence and R0 continue to increase over this time period using the 1:64 cut-point. Lastly, it would be useful to see the x-axis in Figure 4 extended to the start of the time period that FOI is estimated, with accompanying credible intervals.
2) Additional context of EV-D68 in the study setting of England would be useful. While the Introduction does mention AFM cases "in the UK and elsewhere in Europe" (line 53), a summary of reported data on EV-D68/AFM in England prior to this study would provide important context. The Methods refers to "whether transmission had increased over time (before the first reported big outbreak of EV-D68 in the US in 2014)" (lines 133-134), rather than in this setting. It would be useful to summarize the viral genomic data from the region for additional context - particularly since the emergence of a viral clade is highlighted as a co-occurrence with the increased transmissibility detected in this analysis.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This manuscript explores a novel technique to use dyes co-injected with various pharmaceutical reagents, like chemotherapic agents, to assess cellular effects in a cell culture model.
The major premise is that dye diffusion can be detected through fluorescent microscopy and be used as a measure of co-injected drug concentration. In chemotherapy commonly multiple drugs are given simultaneously, however, understanding how to tailor the concentrations of a multi-drug cocktail to each individual is largely trial and error. The authors surmise that perhaps using a cell culture model whereby cancer cells are cultured and then exposed to dye-tracked molecules an optimal multi-drug combination and concentrations can be determined. In other words, the intermixing of various connected drugs can then be fluorescently monitored to elucidate optimal concentrations of multi-drug combinations.
The concept overall is interesting but is relatively preliminary in its proof of concept. The authors note that varying free-diffusion of drugs out of the cell could complicate interpretation and that most of the analysis was done on a relatively short time basis and not longer evaluation periods that were more typical of chemotherapy.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors unexpectedly found that the protein Grb2, an adaptor protein that mediates the recruitment of the Ras guanine-nucleotide exchange factor, SOS, to the EGF receptor, can be recruited to membranes by the immune cell tyrosine kinase Btk. The authors show, using total internal reflection fluorescence (TIRF) microscopy that the interaction with Grb2 is reversible, dependent on the proline-rich region of Btk, and independent of PIP3. These experiments are well performed and unambiguous.
The authors next asked whether Grb2 binding to Btk influences its kinase activity, by evaluating (i) Btk autophosphorylation and (ii) the phosphorylation of a peptide from the endogenous substrate PLC1. The readout relies on non-specific antibody-mediated detection of phosphotyrosine but nevertheless reveals a concentration-dependent increase in both Btk autophosphorylation and PLCy1 phosphorylation. The experiments, however, have only been performed in duplicate and, particularly in the case of PLCy1 phosphorylation, exhibit enormous variability which is not reflected in the example blot the authors have chosen to display in Figure 3C. Comparison of the same, duplicate experiment presented in Figure 3 Supplement 2 paints a very different picture.
The authors next sought to determine which domains of Grb2 are required for activation of Btk. Again, these experiments were only performed in duplicates, and the authors' claims that Grb2 can moderately stimulate the SH3-SH2-kinase module of Grb2 are not well supported by their data (Figure 4C-D).
The authors next asked whether Grb2 stimulates Btk by promoting its dimerization and trans-autophosphorylation. The authors measured the diffusion coefficient of Btk on PIP3-containing supported lipid bilayers in the presence and absence of Grb2. They noted that the diffusion coefficient of individual Btk particles decreases with increasing unlabeled Btk, which they interpret as Btk dimerization. Grb2 does not appear to influence the diffusion of Btk on the membrane (Figure 5A). Presumably, the diffusion coefficient reported here is the average of a number of single-molecule tracks, which should result in error bars. It is unclear why these have not been reported. Next, the authors assessed the ability of Grb2 to stimulate a mutant of Btk that is impaired in its ability to dimerize on PIP3-containing membranes. In contrast to wild-type Btk, autophosphorylation of dimerization-deficient Btk is not enhanced by Grb2. Whilst the data are consistent with this conclusion, again, the experiment has only been repeated once and the western blot presented in Figure 5 Supplement 2 is unreadable. It is also puzzling why Grb2 gets phosphorylated in this experiment, but not in the same experiment reported in Figure 3 Supplement 2.
Finally, the authors argue that Grb2 facilitates the recruitment of Btk to molecular condensates of adaptor and scaffold proteins immobilized on a supported lipid bilayer (SLB) (Figure 6). This is a highly complex series of experiments in which various components are added to supported lipid bilayers and the diffusion of labelled Btk is measured. When Btk is added to SLBs containing the LAT adaptor protein (phosphorylated in situ by Hck immobilized on the membrane via its His tag), it exhibits similar mobility to LAT alone, and its mobility is decreased by the addition of Grb2. The addition of the proline-rich region (PRR) of SOS further decreases this mobility. In this final condition, the authors incubate the reactions for 1 h until LAT undergoes a phase transition, forming gel-like, protein-rich domains on the membrane, shown in Figure 6B. The authors' conclusion that Btk is recruited into these phase-separated domains based on a slow-down in its diffusion is not well supported by the data, which rather indicates that Btk is excluded from these domains (Figure 6B - Btk punctae (green) are almost exclusively found in between the LAT condensates (red)). As such, the restricted mobility of Btk that the authors report may simply reflect the influence of barriers to diffusion on the membrane that result from LAT condensation into phase-separated domains. The authors also present data in Figure 6 Supplement 1 indicating that Grb2 recruitment to Btk is out-competed by SOS-PRR and that Btk does not support the co-recruitment of Grb2 and SOS-PRR to the membrane. These data would appear to suggest that the authors' interpretation of the decreased mobility of Btk on the membrane may not be correct.
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Local file Local file
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2.3-2 Theorem (Completion)
Alternative explanations from Walfram Math world: here.
In brief, you can use an isometry map from a banach space to another subspace in a different Banach space such that it's dense.
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Reviewer #2 (Public Review):
This is an exceptional study that provides conclusive evidence for the existence of a descending pathway from the brain that inhibits nociceptive behavioral outputs in larvae of Drosophila melanogaster. The authors identify molecular both molecular and neuronal/cellular components of this pathway. Converging lines of evidence and conclusive genetic experiments indicate that the neuropeptide, drosulfakinin (DSK), and its receptors (CCK1 and CCK2) function to inhibit nociception behaviors. Interestingly, the authors show that the relevant DSK neurons have cell bodies that are in the larval brain and that these neurons send projections into the thoracic ganglion and ventral nerve cord. Several lines of evidence support the hypothesis that fourth-order nociceptive neurons called Goro, are one relevant target for these outputs. RNAi knockdown of the CCK1 receptor in these cells sensitizes behavioral and physiological responses to noxious heat. Second, the axons of DSK neurons form physical contact with processes of Goro neurons as revealed by GRASP analysis. However, the authors' careful experiments indicate that the contacts between axons and Goro neurites might not be indicative of direct synapses and instead might operate through the bulk transmission of the peptidergic signals. The study raises many interesting questions for future study such as what behavioral contexts might depend on this pathway. Using the CAMPARI approach, the authors do not find that the DSK neurons are activated in response to nociceptive input but instead suggest that these cells may be tonically active in gating nociception. Future studies may find contexts in which the output of the DSK neurons is inhibited to facilitate nociception, or contexts in which the cells are more active to inhibit nociception.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The voltage-gated potassium channel KCNQ1/KCNE1 (IKs) plays important physiological functions, for instance in the repolarization phase of the cardiac action potential. Loss-of-function of KCNQ1/KCNE1 is linked to disease. Hence, KCNQ1/KCNE1 is a highlighted pharmacological target and mechanistic insights into how channel modulators enhance the function of the channel is of great interest. The authors have through several previous studies provided mechanistic insights into how small-molecule activators like ML277 act on KCNQ1. However, less is known about the binding site and mechanism of action of other type of channel activators, which require KCNE1 for their effect. In this study, Chan and co-workers use molecular dynamics approaches, mutagenesis and electrophysiology to propose an overall similar binding site for the KCNQ1/KCNE1 activators mefenamic acid and DIDS, located at the extracellular interface of KCNQ1 and KCNE1. The authors propose an induced-fit model for the binding site, which critically engages residues in the N-terminus of KCNE1. Moreover, the authors discuss possible mechanisms of action of how drug binding to this site may enhance channel function.
The authors address an important question, of broad relevance to researchers in the field. The manuscript is generally well written and the text easy to follow. A strength of the work is the parallel use of experimental and simulation approaches, which enables both functional testing and mechanistic predictions and interpretations. For instance, the authors have experimentally assessed the putative relevance of a large set of residues based on simulation predictions. A limitation is that several methods need to be described in more detail to allow for evaluation of the presented data. Also, a more extensive presentation of representative data would be useful, along with discussions on the putative impact on drug effects of the diverse intrinsic properties of tested mutants.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors provide comprehensive results showing that pharmacological inhibition of PI3K negatively affects heart tube formation via misoriented and slower cardiac movements. They used several cellular and molecular assays to demonstrate the potential mechanisms involved in PI3K-dependent cardiac fusion defects. Moreover, they use several imaging techniques and quantitative assessments to support their findings. Although the manuscript is well-written and most of their results support their conclusions, the manuscript and its findings heavily rely on high concentrations of PI3K small-molecule inhibitors, which will have off-target effects. The off-targets of PI3K pharmacological inhibition should be interpreted with caution and further evaluated. The authors suggest PI3K inhibition mediates heart tube formation throughout PI3K-mediated migration defects rather than PI3K-mediated proliferative defects. However, the authors did not further evaluate this later point; it should be considered carefully.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study, Lamire et al. use a calcium imaging approach, behavioural tests, and pharmacological manipulations to identify the molecular mechanisms behind visual habituation. Overall, the manuscript is well-written but difficult to follow at times. They show a valuable new drug screen paradigm to assess the impact of pharmacological compounds on the behaviour of larval zebrafish, the results are convincing, but the description of the work is sometimes confusing and lacking details.
The volumetric calcium imaging of habituation to dark flashes is valuable, but the mix of responses to visual cues that are not relevant to the dark flash escape, such as the slow increase back to baseline luminosity, lowers the clarity of the results. The link between the calcium imaging results and free-swimming behaviour is not especially convincing, however, that is a common issue of head-restrained imaging with larval zebrafish.
The strong focus on GABA seems unwarranted based on the pharmacological results, as only Picrotoxinin gives clear results, but the other antagonists do not give a consistent results. On the other hand, the melatonin receptor agonists, and oestrogen receptor agonists give more consistent results, including more convincing dose effects.
The pharmacological manipulation of the habituation circuits mapped in the first part does not arrive at any satisfying conclusion, which is acknowledged by the authors. These results do reinforce the disconnect between the calcium imaging and the behavioural experiments and undercut somewhat the proposed circuit-level model.
Overall, the authors did identify interesting new molecular pathways that may be involved in habituation to dark flashes. Their screening approach, while not novel, will be a powerful way to interrogate other behavioural profiles. The authors identified circuit loci apparently involved in habituation to dark flashes, and the potentiation and no adaptation clusters have not been previously observed as far as I know.
The data will be useful to guide follow-up experiments by the community on the new pathway candidates that this screen has uncovered, including behaviours beyond dark flash habituation.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors sequenced a clinical pathogen, Klebsiella FK688, and definitively establish the genetic basis of the carbapenem-resistance phenotype of this strain. They also show that the causal mutations confer reduced fitness under laboratory conditions, and that carbapenem sensitivity readily re-evolves in the lab due to the fitness costs associated with the resistance mutations in the clinical isolate. They also establish that subinhibitory concentrations of ceftazidime select for the otherwise deleterious blaDHA-1 gene. Based on this finding the authors speculate that prior beta-lactam selection faced by the ancestors of Klebsiella FK688 potentiated the evolution of the carbapenem-resistance phenotype of this strain. If this hypothesis is true, then prior history of beta-lactam exposure may generally potentiate the evolution of carbapenem resistance.
Strengths:
From a technical perspective, the findings in this paper are solid. In addition, the authors establish a simple genetic basis for carbapenem resistance in a clinical strain, which is a valuable and non-trivial finding (i.e. they show that the CRE phenotype in this strain is not an omnigenic trait distributed over hundreds of loci).
Weaknesses:
The main weakness of this paper is that the authors draw overly broad conclusions of a conceptual nature from narrow experimental findings. This could be addressed by drawing more modest and narrow implications from the findings.
1) The title of this paper is "Treatment history shapes the evolution of complex carbapenem-resistant phenotypes in Klebsiella spp." But they provide no data on the treatment history of the patient from whom this strain was isolated from. Therefore, the authors have no evidence to support their central claim. Indeed, it is completely possible that this strain never faced beta-lactam selection in the past, or that the patient's hypothetical history of betalactamase was irrelevant for the evolution of FK688. First, it is completely possible that this is a hospital-acquired infection, such that the history of this strain is due to selection in other contexts in the hospital that have little to do with the patient's treatment history. Second, it is completely possible that this strain (the chromosome anyway) has no prior history of beta-lactamase selection, and that it acquired the megaplasmid containing blaDHA-1 via conjugation from some other strain. In this second hypothetical scenario, it is possible that the fitness cost of the blaDHA-1 gene is not particularly high in a different source strain, but that it has some cost in the FK688 strain that it was isolated from. And of course, fitness costs in the human host could be very different than fitness costs in the laboratory, where strains are evolving under strong selection for fast growth. And given the benefit of resistance, it's clear that this strain clearly has a strong fitness advantage over faster-growing sensitive strains in the context of the source patient under antibiotic treatment.
My general point here is that the broad claims made about patient history or prior history shaping the evolution of this strain are largely indefensible because there is no data here to make solid inferences about *how* prior history shaped the evolution of this strain.
2) Historical contingency. The authors claim that their work shows how historical contingency shapes the evolution of resistance. One problem with this claim is that it is trivial- this is only a significant claim if the reader believes that prior history is not important in the evolution of antibiotic resistance, which is a straw-man null hypothesis, to mix a couple metaphors. To be more concrete, clearly strain background (prior history) matters-eliminating the plasmid with the resistance gene eliminates resistance. But that is not particularly surprising, given the past 50 years of evolutionary microbiology literature on plasmids and resistance. By contrast to this work, the major contribution of papers that examine the role of historical contingency in evolution (i.e. various Lenski papers) is that those works *quantitatively* measure the role of history in comparison to other factors (chance, adaptation). Since this work is a deep dive into a single clinical isolate, the data presented here do not and cannot shed light on the role of historical contingency in the emergence of this strain. The authors' claims about the prior history that led to the CRE phenotype are reasonable- but are fundamentally speculative. I have nothing against speculation, as long as it is clear what claims are speculative, and what are concrete implications. But the authors frame these speculative claims as concrete implications of their findings.
3) The authors claim that "[This work] suggests that the strategic combinations of antibiotics could direct the evolution of low-fitness, drug-resistant genotypes". I suppose this is true, but I also think this is a stretch of an implication given these findings. To be blunt, while I suppose it's better to have costly resistance variants that re-evolve sensitivity than to have low-cost high-resistance strains circulating, I think the patient's family would probably disagree that the evolution of a low-fitness drug-resistant genotype was good or strategic in the clinical context, even if better from a public health perspective. Low-fitness drug-resistant strains are just as lethal under clinical antibiotic concentrations!
The authors do show the plausibility of their hypothesis/model that prior beta-lactam selection is sufficient to potentiate the evolution of carbapenem-resistance (by the additional ompK loss-of-function mutation). I think those findings are very nice. But the authors undermine their results by extrapolating too far from their data. Hence, I think narrowing the scope of the implications would improve this paper.
In addition to narrowing the scope of the implications as written, I also would like to add that there may be other ways of framing this paper (other than historical contingency) that may make the significance of this work more apparent to a broader audience. This may be worth considering during the revision process.
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Reviewer #2 (Public Review):
Toxoplasma gondii (Tg) and Plasmodium falciparum (Pf) are two protozoan parasites that both present threats to global human health as the causal agents of toxoplasmosis and malaria, respectively. In absence of effective vaccines, disease control relies heavily on the use of drugs aimed at treating infected patients to inhibit parasitic growth and eventually kill parasites to interrupt the parasitic lifecycle. These obligate intracellular vacuole-dwelling parasites quickly attach to their host cells before actively pinching through their plasma membranes and completing their complex respective lifecycles.
Kumar et al. seek to understand the complex process of host cell recognition, attachment, and invasion in order to devise possible strategies to possibly interfere and/or block to prevent invasion of the host cell or compromise egress from the infected cell. Characterizing the 3D structure at atomic resolution and dynamics of the glideosome molecular machinery involved in parasite attachment and invasion/egress provides grounds for the future rational design of novel anti-parasitic therapies targeting novel molecular targets and phylum-specific biological processes. Toxoplasma belongs to the same large family of obligate intracellular parasites such as the malaria parasite Plasmodium. These protozoa actively attach and glide at the surface of their target host cell before invading it. Such motility and propulsion at the surface of the host cell are powered by a large protein complex, the glideosome.
The article elegantly combines structural, biophysical, biochemical, computational, and cell biology approaches to dissect the structure and mechanism of action of TgGAC (and PfGAC).
The crystal structure of TgGAC was solved at an apparent 2.7A resolution by se-mad and although it is overall well described it requires further polishing in terms of model quality and accuracy. This is a very large protein, so it represents a considerable amount of work to build and refine. We note deficiencies in the way refinement (atomic displacement parameters and model building in general) and phasing statistics description were carried out or presented. This warrants further inspection and requires significant improvement and corrections to meet the usual standards expected from this field of research.
Solution scattering data while supporting the model of a conformational change between a compact (closed) conformation observed in the crystal obtained at pH 5 and an extended monomeric conformation observed at pH 8 more amenable to interactions with other cellular partners in the context of a functional glideosome needs some clarification. Because of the way proteins seem to be prepared for the SAXS analysis, I have some objections to the interpretation of some of the data.
The biochemical analysis of lipid binding specificity of the small c-terminal pleckstrin-like domain of TgGAC and PfGAC (full-length or c-terminal domain) using liposome binding assays, elegant NMR relaxation methods but also molecular dynamics on full-length GAC models are extremely convincing and support all authors claim.
The fact that however the CTD lipid binding activity is not required in vivo is a bit surprising although CTD seems required to stabilize the protein in vitro.
The section describing the hydrogen-deuterium exchange analysis of TgGAC conformation is confusing as it stands and requires clarification. It fails to be compelling in my personal opinion.
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Reviewer #2 (Public Review):
The study aimed to provide information on the extent to which the COVID-19 pandemic impacted cervical cancer (CC) screening and treatment in 3 Canadian provinces. The survey methodology is appropriate, and the results provide detailed descriptive statistics by province and type of practice. The results support the authors' conclusions. This evidence together with data gathered from other national surveys may provide baseline data on the impact of the pandemic on CC outcomes such as late-stage diagnoses and CC treatment outcomes due to these delays.
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Reviewer #2 (Public Review):
OTOP channels are relatively newly discovered and their physiology is poorly understood. Zn activation appears to be a differentiating feature of OTOP function and Zn is a pharmacological tool for research. The Zn potentiation of OTOP3 is a curious phenomenon that is studied very carefully here. The language in this manuscript is appropriately nuanced in the interpretation of results and is delightfully agnostic with regards to function vs binding. The major strengths of this work are the very thorough characterization of the zinc effect and the identification of the 11-12 loop as necessary and sufficient for the zinc effect.
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Reviewer #2 (Public Review):
The authors investigated patterns of fMRI activation for familiar words in two groups of deaf people. One "language rich" group received exposure to sign from birth, whereas the "language poor" group included kids born to hearing parents who had limited exposure to language during the first few years of life. The primary findings involved group differences in BOLD activation patterns across different areas of interest within the semantic network when participants made intermittent 1-back category judgments for words appearing in succession.
There was much to be liked about this study, including the rigor of the methods and the novel contrasts of two deaf samples. These strengths were balanced by a number of questions about the assumptions and theoretical interpretations underlying the data. I will elaborate on the major points in the paragraphs to follow, but briefly, the ways in which the authors are framing critical period constraints in language fundamentally differ from the standard nativist perspectives (e.g., Chomsky, Lenneberg). The assumptions of what constitutes a deprivation model require further justification and perhaps recasting to avoid unnecessary stigma (i.e., this reviewer was uncomfortable with the assertion that being born deaf to hearing parents by default constitutes deprivation). The introduction lacked principled hypotheses that motivated the choice of comparing abstract and concrete words, and potential accounts of group differences were underdeveloped (e.g., how do parents in China typically react to having a deaf child, and what supports are in place for preventing language deprivation? Are newborn infants universally screened for hearing loss in China? The answers to these questions might help the readers to understand why/how deaf children in this circumstance might experience deprivation).
References to critical periods require a bit more elaboration with respect to lexical-semantic vs. semantic acquisition. The nature of the critical period in language acquisition remains controversial with respect to its constraints. Lenneberg and Chomsky speculated that the limit of the critical period for language acquisition was about puberty (13ish years of age). This is much older than the deaf sample tested here so arguments about aging out of the critical period at least for language acquisition need more nuance. Another issue relates to learning semantic mappings vs. learning language as falling under the same critical period umbrella. This seems highly unlikely as semantic acquisition in early childhood is aided by linguistic labeling but would likely occur in parallel even in the context of language deprivation. Much of the prior literature on critical periods and nativist approaches to language development has focused on syntactic acquisition and elements such as recursion rather than a mapping of symbols to conceptual referents. This makes the critical period group comparison somewhat tenuous because what you are really interested in is a critical period for word meaning acquisition not the more general case of syntactic competency.
The point above is highlighted in the following statement underlying one of the primary assumptions of the study:<br /> Pg. 3, "Here, we take advantage of a special early-life language-deprivation human model: individuals who were born profoundly deaf in hearing families and thus had very limited natural language exposure (speech or sign) during the critical period of language acquisition in early childhood"
"hypofunction of the language system as a result of missing the critical period of language acquisition" (pg 3), same critique as previous - the critical period window is thought to be 13ish years old.
There are a couple of problems with this assertion/assumption. Although it is true that most children who are born deaf have hearing parents, it is not justifiable to label this condition an early-life deprivation model. Hearing parents who are extremely motivated to learn sign language and pursue related language enrichment strategies can successfully offset many of these effects. Similarly, it is not inconceivable that a deaf child born to a deaf parent might be neglected or abandoned without the benefit of early sign exposure. My argument here is that classifying deaf children born to hearing parents as automatically 'language deprived' is potentially both stigmatizing and scientifically unjustified.
Pg. 6 "It should be noted that the neural semantic abstractness effect does not equate with language-derived semantic knowledge, as it might arise from some nonverbal cognitive processes that are more engaged in abstract word processing (Binder et al., 2016)." - I had great difficulty understanding what this meant.
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Reviewer #2 (Public Review):
This paper describes a relatively unbiased and sensitive method for identifying the contributions of different behavioral parameters to neural activity. Their approach addresses, in an elegant way, several difficulties that arise in modeling of neuronal responses in population imaging data, namely variations in temporal filtering and latency, the effects of calcium indicator kinetics, interactions between different variables, and non-linear computations. Typical approaches to solving these problems require the introduction of prior knowledge or assumptions that bias the output, or involve a trade-off between model complexity and interpretability. The authors fit individual neuron's responses using neural network models that allow for complex non-linear relationships between behavioral variables and outputs, but combine this with analysis, based on Taylor series approximations of the network function, that gives insight into how different variables are contributing to the model.
The authors have thoroughly validated their method using simulated data as well as showing its applicability to example state of the art data sets from mouse and zebrafish. They provide evidence that it can outperform current approaches based on linear regression for the identification of neurons carrying behaviorally relevant signals. They also demonstrate use cases showing how their approach can be used to classify neurons based on computational features. They have provided Python code for the implementation and have explained the methods well, so it will be easy for other groups to replicate their work. The method could be applied productively to many types of experiments in behavioral and systems neuroscience across different model systems. Overall, the paper is clearly written and the experiments are well designed and analysed, and represent a useful contribution to the neuroscience field.
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Reviewer #2 (Public Review):
This important paper is a real tour de force and combines functional MRI, behaviour, and brain stimulation to characterise the effect of stimulation of the lateral habenula in a rodent model for depression. The results are stunning and the data presented seems compelling.
My only comment is I would like more discussion on the relevance of these results for the treatment of depression in humans, both in terms of the rodent model and in terms of the results shown in this study.
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Reviewer #2 (Public Review):
This manuscript is clear in that it shows no/minimal weight gain in a mouse model of trisomy 21 compared to the control mouse, even under a high-calorie diet. The difference is the clear demonstration of the increased expression of sarcolipin. It is important that the expression of SERCA was also shown not different between the genotypes. Additionally, an important result is that manipulating the skeletal muscle was sufficient to promote weight loss without the need for hypermetabolism in other tissues such as adipose tissue.
- A clear explanation of why the expression of sarcolipin/hypermetabolism is different between mouse and human under the same condition would be useful.
- p.12-13 and15. The language around 'futile' cycling is not correct because Ca movement through the sarcoplasmic reticulum of the resting fiber is essential to the function of the muscle. Firstly, the cycle of Ca through the SR is through the ryanodine receptor (RyR) as well as due to slippage through the SERCA (PMID: 11306667, PMID: 35311921). This is not made clear anywhere in the manuscript. Ca leak out of the SR through RyR is an essential component to the control/setting of the resting cytoplasmic [Ca2+] via the activation of store-operated Ca2+ entry, which is in a balance with the activation of the PMCA on the t-system membrane (PMID: 35218018). The SERCA resequesters the leaked Ca2+ from the SR. It is not possible that the resting [Ca2+] is set by the reduced efficiency of the SERCA, as indicated in the ms (PMID: 20709761). It is expected that the mito [Ca2+] steady state is set by the raised resting cyto [Ca2+] (PMID: 20709761). Ca2+ transients during EC coupling will promote transient increases in mito Ca2+ (PMID: 21795684, PMID: 36121378), but not steady-state increases. Some of these problems are highlighted by the errors in the diagram Fig 5D: please change/correct (i) the invagination of the sarcolemma is called the t-system; (ii) the cycle of Ca leak through the SR starts with RyR Ca leak, where the Ca is resequestered by the SERCA, in addition to Ca slippage through the pump. Draw a RyR opposite the t-system on the SR terminal cisternae. The heat generated by SERCA is absorbed in the cytoplasm, metabolites enter the mito and the OxPhos generates heat (PMID: 31346851). (iii) Ca does not enter mito because it cannot get into the SR (the resting cyto Ca is controlled by the t-system/plasma membrane, PMID: 20709761, PMID: 35218018). Please redraw.
- The changing of the properties of the muscle towards oxidative properties is consistent with the expression of sarcolipin in mouse muscle (all of it is in type II fibers). It is important to show whether the muscles have fiber-type shifts. Please report the fiber types of the muscles that have been surveyed in this project.
- Non-shivering thermogenesis (NST) is mentioned in this manuscript as the means of hypermetabolism, as has the lengthened duration of the cyto Ca transients during EC coupling. It is not clear at all what the contribution of NST compared to the increased work of the SERCA to clear released Ca from the cyto to the hypermetabolism. What are the relative proportions? If sarcolipin is largely for NST, then hypermetabolism is about the resting muscle.
- The link that SLN is causing more ATP use at the pump but the heat generated by OxPhos in mito is important and should be made, see Barclays' work (eg. PMID: 31346851). A direct link between the SERCA function and mito function is occurring but I currently don't see one being made in the ms. This could be made clear in Fig 5D diagram.
- p.22. "The reprogramming of glycolytic...elevated Ca transients...". The language is wrong here. Oxidative fibers do not have elevated Ca transients compared to glycolytic. The amplitude of Ca release is greater in glycolytic and the duration of the transient is longer in the oxidative (eg. PMID: 12813151).
- p.22. "as less calcium is being transported into the SR due to uncoupling of the SERCA pumps". The same amount of Ca is being transported, just at the expense of more ATP than would be the case in the absence of SLN. Otherwise, the SR Ca2+ content would not be at a steady state while the SR continuously leaks Ca2+.
- p.23. Tavi & Westerblad (PMID: 21911615) show how Ca transient amplitude and frequency signal in slow and fast twitch fibres. Here, we are not concerned with what is happening in myotubes, where the SR is less developed than in adult fibres.
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Reviewer #2 (Public Review):
The authors present a new method of determining the boundaries of superficial, input, and deep cortical layers from laminar multielectrode recordings in non-human primates.<br /> It is based on using the generalized phase (GP) of the LFP (filtered between 5-50Hz) in conjunction with phase coupling (to the GP) of spiking activity (from single or multi-units). They report that phase coupling differs between layers. Critically the preferred LFP phase differs between the deep layers and layers above (input/superficial layers), and this measure can be reliably used to infer input/deep layer boundaries.
Spiking on a given channel (for all channels) tended to occur at +/- pi relative to LFPs recorded at superficial/input layers, but at 0pi relative to deep-layer LFPs. This relationship can be used to estimate the input/deep layer boundary. Generally, the estimate obtained was well correlated with measures derived from traditional CSD analysis. Where discrepancies occurred between CSD and phase coupling-based depth estimates, phase coupling-based depth estimates correlated better with additional measures such as firing rates, and low/high-frequency spectral power cross-over, that have been previously reported to align with cortical depth.
These results were present in areas MT (marmoset), V4 (macaque), and PFC (marmoset), and can be performed on short sequences of data under multiple experimental conditions.
This is a novel, easier, and potentially more precise way to assign cortical depth in non-human primates, which may prove useful to the wider research community.
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Reviewer #2 (Public Review):
Previous work by the same group has shown that the potassium channel TWIK2 contributes to the activation of the NLRP3 inflammasome in macrophages. In this manuscript, the authors provide new insights into the biology of TWIK2 and show that TWIK2 translocated to the plasma membrane of macrophages following stimulation with ATP. They show that ATP stimulation induced exocytosis, via a process dependent on the purinergic receptor P2X7, the presence of calcium and vesicle fusion. Genetic deletion of P2X7, depletion of calcium, and pharmacological inhibition of vesicle fusion collectively contributed to the inhibition of current changes and NLRP3 inflammasome activation. The authors also show that the endosomal protein Rab11a translocated to the plasma membrane following ATP stimulation and that Rab11a contributed to NLRP3 inflammasome activation. Depletion of Rab11a in macrophages prevented lung injuries and NLRP3 inflammasome activation in mice treated with LPS.
The major strength of the work is the use of a combination of cell culture work and a mouse model to address the cell biology of inflammasome activation.<br /> The weakness is that the current set of data is not able to fully support the conclusion that Rab11a, P2X7 and calcium influx mediate the translocation of TWIK2 to the plasma membrane. The characterisation of inflammasome activation is also partial. If these weaknesses can be addressed, the authors would have achieved their aims and increased the impact of their work in the field of inflammasome biology.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Overall, I thoroughly enjoyed reading and reviewing this manuscript. I think that it contributes importantly to the literature and illustrates an appealing way to connect neural data to normative ideas, phenomenological models, and mechanic explanations. In particular, the suggestion that the retina is specifically tailored to support predictive information encoding is normatively appealing, because animals obtain ecological advantages by anticipating their environment. It would be very exciting to figure out how the retina accomplishes this task. The authors begin their analysis of this question by using spatiotemporal receptive fields to phenomenologically describe how retinal ganglion cells nonlinearly integrate visual signals presented in different regions of the visual field. This allows them to identify several spatiotemporal components of the receptive field, termed kernels, that contribute differentially to predictive information encoding. The authors then use neural circuit modeling to reproduce these receptive field properties using biologically plausible bipolar cell inputs to the retinal ganglion cells. This allows them to hypothesize how specific circuit properties may contribute to predictive information encoding. For example, the authors' current models allow them to address the roles of bipolar cell nonlinearities, spatially local coupling between bipolar cells, patchy bipolar cell to retinal ganglion cell connectivity, and activity-dependent neuronal adaptation.
By connecting predictive information encoding to receptive field properties and candidate circuit mechanisms, the authors hope to identify biological fingerprints of predictive information encoding that could carry over to other neural circuits in the brain. I did not find this component of the argument to be convincing. My main concern is that stimulus statistics and neuronal activity statistics dually contribute to the meaning of predictive information, but this study did not dissect the role of stimulus statistics at all. As a result, I think the paper places too much emphasis on mechanism, and not enough emphasis on natural sensory statistics. The authors do devote a figure to illustrating that their receptive field estimation procedure is insensitive to the stimulus ensemble used for fitting (Fig. 4). Indeed, perhaps the receptive field kernels would stay similar if they were fit to natural stimuli. However, it would still be the case that the pattern of predictive information encoding captured by these kernels would strongly vary as a function of stimulus ensemble. For example, here the authors use random synthetic stimuli with relatively short correlation times, which means that the temporal horizon for predictive information encoding is limited (see Liu et al., Nat Neuro, 2021). The pattern of predictive information encoding for natural stimuli may be very different, and it may be that different receptive field components and neural circuit mechanisms contribute to predictive information encoding in that context. Similarly, other sensory systems are adapted to process stimuli with other sensory statistics, and I do not think it's clear that the receptive field components and neural circuit mechanisms identified here will be universally relevant.
The manuscript uses information theoretic methods to infer multiple kernels that describe linear stimulus features that modulate spiking activity of retinal ganglion cells. A potentially interesting limitation of the study is that it assumes that "outputs of these kernels are summed prior to passing through a common nonlinearity." However, many other papers have found that neuronal activity is sometimes governed by multiple linear features that cannot be summed prior to their nonlinear action. It would be interesting to know whether these kinds of features contribute to predictive information encoding in the retina.
A major problem with the manuscript is that its methods are inadequately described. I think that a major revision will be required before readers will be able reproduce the manuscript's results. These missing methodological details also make it difficult for readers to fully assess the manuscript's conclusions, strengths, and limitations.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
By analyzing hundreds of genomes, authors studied the so-called elusive genes, i.e., genes present in human genome but their orthologs deleted in some other mammals. Authors showed their bioinformatic pipeline of identifying these genes (Fig. 1), the genomic or evolutionary features of these genes (e.g. high GC content, Fig. 2), conservation of these features in other vertebrates including remotely related gar or shark (Fig. 3) together with polymorphism level, transcriptional features, epigenetic features of these genes (Fig. 4-6). Finally, in the Discussion section, the authors showed the chromosomal contributions of elusive genes and argued that these genes could be derived from ancient microchromosomes (Fig. 7).
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Whether and how molecularly defined neuronal groups in the spinal cord process distinct modalities are of great interest. In this study, Boyle et al. characterized roles of inhibitory neurons expressing NPY in adult mice. By using chemogenetic, electrophysiological tools and behavioral measurements, the authors discovered that activating NPY+ interneurons strongly reduced pruritogen-evoked itch and reflexive behaviors (acute nociception or under inflammation / neuropathic pain states). Silencing NPY+ spinal interneurons enhanced spontaneous and chemical itch in a GRPR+ neurons dependent manner. The authors concluded that, unlike previous findings suggesting that these neurons are selective for mechanical itch, adult NPY+ interneurons play dual roles in gating various types of itch and pain.
Strengths:
The authors performed careful characterization and comparisons between development lineage and adult spinal neurons expressing NPY. This lays the foundation of the current study. The behavioral measurements were also well designed with proper controls.
Weaknesses:
There is inadequate discussion about previous studies of NPY interneurons. Specifically, the authors should address why a more restricted subset of these neurons (this study) have broader effects than seen previously.
I cannot see the reason for including results from manipulation of Dyn+ interneurons in this paper. First, the title does not reflect roles of spinal Dyn+ population. In addition, without further experiments characterizing relationships between NPY and Dyn interneurons in modulating itch and/or nociception, Dyn datasets seem to deviate from the main theme.
While the authors provided convincing evidence that GRPR+ neurons serve as a downstream effector of NPY+ neuron evoked itch, the relationship between GRPR and NPY neurons in modulating pain is not examined. Therefore, Fig. 7B is pure speculation and should be removed.
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Reviewer #2 (Public Review):
The paper by Huan, Yong, et al. studies epithelial cell extrusion in MDCK monolayers grown on sinusoidally wavy surfaces in varying media osmolarities, finding that both curvature and osmolarity-mediated basal hydraulic stress spatially regulate extrusion events. The authors fabricated wavy substrates of varying periods and amplitude out of PDMS (and PA hydrogels) and monitored monolayer evolution and cell extrusion over time, by combining live-cell imaging with a convolutional network-based algorithm for automatic detection of extrusions.
In general, the study has been elegantly designed, starting with convincing evidence for enhanced extrusion rates in concave valleys with respect to convex hills. Next, the authors showed that hyper-osmotic medium reduced cell extrusion rate, which was demonstrated in a variety of different media compositions (e.g. with sucrose, DMSO, or NaCl), while hypo-osmotic medium increased cell extrusion rate. Additionally, the authors applied reflection interference contrast microscopy to reveal fluid spaces between the substrate and the basal side of the monolayer, which were found to grow when media composition was altered from hyper-osmotic to normal osmotic conditions. Using a 3D traction force microscopy approach, the authors demonstrated that cells on convex regions apply a downward pointing force on the substrate, opposite to cells on the concave regions. This was linked to a larger basal separation on the concave valleys as opposed to the convex hills. Finally, the authors focussed on the FAK-Akt pathway to explore the hypothesis that basal hydraulic stress interferes with focal adhesions, leading to differences in cell extrusion rates in media of different osmolarity and on convex or concave surfaces.
Despite the host of relevant experiments and the interesting data acquired with a variety of techniques, some aspects of the manuscript would need to be strengthened or explained in more detail to better support the claims and to provide more convincing evidence.
1) The sinusoidal wavy substrate that the authors use in their investigation is interesting and relevant, but it is important to realise that this is a single-curved surface (also known as a developable surface). This means that the Gaussian curvature is zero and that monolayers need to undergo (almost) no stretching to conform to the curvature. The authors should at least discuss other curved surfaces as an option for future research, and highlight how the observations might change. Convex and concave hemispherical surfaces, for example, might induce stronger differences than observed on the sinusoidal substrates, due to potentially higher vertical resultant forces that the monolayer would experience. The authors could discuss this geometry aspect more in their manuscript and potentially link it to some other papers exploring cell-curvature interactions in more complex environments (e.g. non-zero Gaussian curvature).
2) The discussion of the experiments on PAM gels is rather limited. The authors describe that cells on the PAM gels experience fewer extrusions than on the PDMS substrates, but this is not discussed in sufficient detail (e.g. why is this the case). Additionally, the description of the 3D traction force microscopy and its validation is quite limited and should be extended to provide more convincing evidence that the measured force differences are not an artefact of the undulations of the surface.
3) The authors show nuclear deformation on the hills and use this as evidence for a resultant downward-pointing force vector. This has, indeed, also been observed in other works referenced by the authors (e.g. Werner et al.), and could be interesting evidence to support the current observations, provided the authors also show a nuclear shape on the concave and flat regions. The authors could potentially also characterise this shape change better using higher-resolution data.
4) The U-net for extrusion detection is a central tool used within this study, though the explanation and particularly validation of the tool are somewhat lacking. More clarity in the explanation and more examples of good (or bad) detections would help establish this tool as a more robust component of the data collection (on all geometries).
5) The authors study the involvement of FAK in the observed curvature-dependent and hydraulic stress-dependent spatial regulation of cell extrusion. In one of the experiments, the authors supplement the cell medium with FAK inhibitors, though only in a hyper-osmotic medium. They show that FAK inhibition counteracts the extrusion-suppressing effect of a hyper-osmotic medium. However, no data is shown on the effect of FAK inhibitors within the control medium. Would the extrusion rates be even higher then?
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Reviewer #2 (Public Review):
The authors are trying to distinguish between four models of the role of glypicans (HSPGs) on the Dpp/BMP gradient in the Drosophila wing, schematized in Fig. 1: (1) "Restricted diffusion" (HSPGs transport Dpp via repetitive interaction of HS chains with Dpp); (2) "Hindered diffusion" (HSPGs hinder Dpp spreading via reversible interaction of HS chains with Dpp); (3) "Stabilization" (HSPGs stabilize Dpp on the cell surface via reversible interaction of HS chains with Dpp that antagonizes Tkv-mediated Dpp internalization); and (4) "Recycling" (HSPGs internalize and recycle Dpp).
To distinguish between these models, the authors generate new alleles for the glypicans Dally and Dally-like protein (Dlp) and for Dpp: a Dally knock-out allele, a Dally YFP-tagged allele, a Dally knock-out allele with 3HA-Dlp, a Dlp knock-out allele, a Dlp allele containing 3-HA tags, and a Dpp lacking the HS-interacting domain. Additionally, they use an OLLAS-tag Dpp (OLLAS being an epitope tag against which extremely high affinity antibodies exist). They examine OLLAS-Dpp or HA-Dpp distribution, phospho-Mad staining, adult wing size.
They find that over-expressed Dally - but not Dlp - expands Dpp distribution in the larval wing disc. They find that the Dally[KO] allele behaves like a Dally strong hypomorph Dally[MH32]. The Dally[KO] - but not the Dlp[KO] - caused reduced pMad in both anterior and posterior domains and reduced adult wing size (particularly in the Anterior-Posterior axis). These defects can be substantially corrected by supplying an endogenously tagged YFP-tagged Dally. By contrast, they were not rescued when a 3xHA Dlp was inserted in the Dally locus. These results support their conclusion that Dpp interacts with Dally but not Dlp.
They next wanted to determine the relative contributions of the Dally core or the HS chains to the Dpp distribution. To test this, they over-expressed UAS-Dally or UAS-Dally[deltaHS] (lacking the HS chains) in the dorsal wing. Dally[deltaHS] over-expression increased the distribution of OLLAS-Dpp but caused a reduction in pMad. Then they write that after they normalize for expression levels, they find that Dally[deltaHS] only mildly reduces pMad and this result indicates a major contribution of the Dally core protein to Dpp stability. The "normalization" is a key part of this model and is not mentioned how the normalization was done. When they do the critical experiment, making the Dally[deltaHS] allele, they find that loss of the HS chains is nearly as severe as total loss of Dally (i.e., Dally[KO]). Additionally, experimental approaches are needed here to prove the role of the Dally core.
Prior work has shown that a stretch of 7 amino acids in the Dpp N-terminal domain is required to interact with heparin but not with Dpp receptors (Akiyama, 2008). The authors generated an HA-tagged Dpp allele lacking these residues (HA-dpp[deltaN]). It is an embryonic lethal allele, but they can get some animals to survive to larval stages if they also supply a transgene called “JAX” containing dpp regulatory sequences. In the JAX; HA-dpp[deltaN] mutant background, they find that the distribution and signaling of this Dpp molecule is largely normal. While over-expressed Dally can increase the distribution of HA-dpp[deltaN], over-expression of Dally[deltaHS] cannot. These latter results support the model that the HS chains in Dally are required for Dpp function but not because of a direct interaction with Dpp.
In the last part of the results, they attempt to determine if the Dpp receptor Thickveins (Tkv) is required for Dally-HS chains interaction. The 2008 (Akiyama) model posits that Tkv activates pMad downstream of Dpp and also internalizes and degrades Dpp. A 2022 (Romanova-Michaelides) model proposes that Dally (not Tkv) internalizes Dpp.
To distinguish between these models, the authors deplete Tkv from the dorsal compartment of the wing disc and found that extracellular Dpp increased and expanded in that domain. These results support the model that Tkv is required to internalize Dpp. They then tested the model that Dally antagonizes Tkv-mediated Dpp internalization by determining whether the defective extracellular Dpp distribution in Dally[KO] mutants could be rescued by depleting Tkv. Extracellular Dpp did increase in the D vs V compartment, potentially providing some support for their model. However, there are no statistics performed, which is needed for full confidence in the results. The lack of statistics is particularly problematic (1) when they state that extracellular Dpp does not rise in ap>tkv RNAi vs ap>tkv RNAi, dally[KO] wing discs (Fig. 6E) or (2) when they state that extracellular Dpp gradient expanded in the dorsal compartment when tkv was dorsally depleted in dally[deltaHS] mutants (Fig. 6I). These last two experiments are important for their model but the differences are assessed only visually. In fact, extracellular Dpp in ap>tkv RNAi, dally[KO] (Fig. 6B) appears to be lower than extracellular Dpp in ap>tkv RNAi (Fig. 6A) and the histogram of Dpp in ap>tkv RNAi, dally[KO] is actually a bit lower than Dpp in ap>tkv RNAi, But the author claim that there is no difference between the two. Their conclusion would be strengthened by statistical analyses of the two lines.
Strengths:
1. New genomically-engineered alleles
A considerable strength of the study is the generation and characterization of new Dally, Dlp and Dpp alleles. These reagents will be of great use to the field.
2. Surveying multiple phenotypes
The authors survey numerous parameters (Dpp distribution, Dpp signaling (pMad) and adult wing phenotypes) which provides many points of analysis.
Weaknesses:
1. Confusing discussion regarding the Dally core vs HS in Dpp stability. They don't provide any measurements or information on how they "normalize" for the level of Dally vs Dally[deltaHS]? This is important part of their model that currently is not supported by any measurements.
2. Lacking quantifications and statistical analyses:
a. Why are statistical significance for histograms (pMad and Dpp distribution) not supplied? These histograms provide the key results supporting the authors' conclusions but no statistical tests/results are presented. This is a pervasive shortcoming in the current study.
b. dpp[deltaN] with JAX transgene - it would strengthen the study to supply quantitative data on the percent survival/lethal stage of dpp[deltaN] mutants with or without the JAK transgene <br /> c. The graphs on wing size etc should start at zero. <br /> d. The sizes of histograms and graphs in each figure should be increased so that the reader can properly assess them. Currently, they are very small.
The authors' model is that Dally (not Dlp) is required for Dpp distribution and signaling but that this is not due to a direct interaction with Dpp. Rather, they posit that Dally-HS antagonize Tkv-mediated Dpp internalization. Currently the results of the experiments could be considered consistent with their model, but as noted above, the lack of statistical analyses of some parameters is a weakness. One problematic part of their result for me is the role of the Dally core protein (Fig. 7B). There is a mis-match between the over-expression results and Dally allele lacking HS (but containing the core). Finally, their results support the idea that one or more as-yet unidentified proteins interact with Dally-HS chains to control Dpp distribution and signaling in the wing disc.
There is much debate and controversy in the Dpp morphogen field. The generation of new, high quality alleles in this study will be useful to Drosophila community, and the results of this study support the concept that Tkv but not Dally regulate Dpp internalization. Thus the work could be impactful and fuel new debates among morphogen researchers. <br />
The manuscript is currently written in a manner that really is only accessible to researchers who work on the Dpp gradient. It would be very helpful for the authors to re-write the manuscript and carefully explain in each section of the results (1) the exact question that will be asked, (2) the prior work on the topic, (3) the precise experiment that will be done, and (4) the predicted results. This would make the study more accessible to developmental biologists outside of the morphogen gradient and Drosophila communities.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Neutrophils are the most abundant circulating leukocytes in human. They play important roles in innate immune responses to infections and tissue injuries. Although they are dept in phagocytosis of microbes, neutrophils are not known to normally conduct efferocytosis or phagocytose host cells including apoptotic cells and play a significant role in apoptotic cell removal. In this report the authors provide evidence to suggest that neutrophils are involved in removal of apoptotic hepatocytes with certain specificity (i.e., they do not remove HEK293 or HUVEC endothelial cells). Moreover, the authors also show that neutrophils can burrow into the target cells and possibly ingest the target cells from the inside. The authors thus term this neutrophil-mediated efferocytosis process as "perforocytosis". Furthermore, evidence is provided to suggest that this neutrophil-mediated efferocytosis process keeps the number of apoptotic cells low in the livers and that defects in the processes may associate with autoimmune liver (AIL) disease phenotypes. Therefore, many of these findings are novel and the study is of important implications in our understanding of the role of neutrophils in autoimmune disease.
By examination of HE-stained, noncancerous liver tissue sections from patients with hepatocellular carcinoma and hepatic hemangioma, the authors observed that cells with neutrophil nuclear morphology were inside apoptotic hepatocytes. The authors also further characterized this observation by staining the sections with neutrophil and apoptosis markers. In addition, the authors observed the same phenomena in mouse livers using intravital microscopy, which also recorded the time course of the disappearance of a neutrophil-associated apoptotic cell. The author went on further characterization of neutrophil-mediated efferocytosis of cultured hepatic cells in vitro and demonstrated the process was specific for apoptotic hepatic cells, but not HEK293 or endothelial cells. The in vitro system was then used to characterize the molecular bases for neutrophil-mediated efferocytosis of apoptotic hepatic cells. The evidence was provided to suggest that IL1b and IL-8 released from and selectins upregulated in apoptotic hepatic cells were important. Importantly, the authors used two methods to deplete the neutrophils and showed that the neutrophil depletion increased apoptotic cells in livers. Finally, the authors showed that neutrophil depletion caused defects in liver function parameters. At the end, the authors presented evidence to suggest that AIL disease may be due to defective neutrophils that fail to perform "perforocytosis."
Although the evidence in its totality indicates that neutrophils burrow into apoptotic hepatocytes, the significance of this "perforocytosis" phenomenon and the circumstances under which it may occur remain to be better defined. In both neutrophil depletion models, the TNUEL-positive cells were not definitively identified rather than assuming they were hepatocytes. In addition, there are discrepancies in the number of neutrophils and apoptotic cells in mouse liver studies; Figure 2a WT (many neutrophils; locations unclear) vs Figure 5A Ctr (a few neutrophils that appear in or near a vessel), and Figure 2a DTR (a few apoptotic cells) vs Figure 5A Depletion (many apoptotic cells). Importantly, Figure 5a Ctrl, which is presumably a section from a mouse without any surgical treatment or without inflammation, the sole TUNNEL signal does not appear to be associated with neutrophils. Does this mean that "perforocytosis" primarily occurs in inflamed livers (Of note, human liver samples in Figure 1 are from patient with tumors. There should be inflammation in the livers of these patients). The data on human AIL patient neutrophils raises more questions: how many AIL patients have been examined? Do these AIL neutrophils lack IL1, IL8 receptors, and/or selectin ligands? Are there increases in apoptotic hepatocytes in AIL patients? Additionally, the overall numbers of apoptotic cells even in the absence of neutrophils are rare; thus, it is questionable that such rarity of apoptotic cells can cause significant AIL phenotypes.
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soundcloud.com soundcloud.com
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The role of the actin-binding protein palladin (PALLD) in cardiomyocyte development, growth, and function has not been defined. In order to address this question, the authors first identified that CARP and FHOD1 interact with PALLD in cardiomyocytes. They then performed cardiomyocyte selective deletion of PALLD in embryonic and adult mice and discovered that deletion of PALLD in adult mice leads to dilated cardiomyopathy (DCM) and intercalated disc ultrastructural changes. In contrast, embryonic deletion of cardiomyocyte PALLD did not cause a cardiomyopathy phenotype in neonatal or adult animals.
1. The divergent cardiac phenotypes of the embryonic deletion of cardiomyocyte PALLD (no cardiomyopathy) versus the adult deletion of cardiomyocyte PALLD (dilated cardiomyopathy(DCM)) is an interesting result. The authors speculate that embryonic deletion of PALLD induces compensatory pathways that prevent the development of adult cardiomyopathy in these mice. However, these compensatory pathways remain unexplored.<br /> 2. The authors discovered that mice with adult cardiomyocyte deletion of PALLD had significant changes in the cardiomyocyte intercalated disc (ICD) ultrastructure. They suggest these changes in ICD ultrastructure contribute to DCM formation in the adult PALLD deletion mice (line 270). However, it remains unclear if these changes in ICD ultrastructure are specific to mice with adult deletion of PALLD.<br /> 3. The different transgenic Cre mouse lines may be an alternative explanation for the divergent cardiac phenotypes in the embryonic versus adult deletion of cardiomyocyte PALLD. The tamoxifen dose administered for the inducible Myh6:MerCreMer mice was 30mg/kg/day x 5 which has been reported to lead to the induction of cardiomyocyte DNA damage response pathways (Dis Model Mech. 2013 Nov; 6(6): 1459-1469, J Cardiovasc Aging 2022;2:8). The electron micrograph experiments in Figure 5 did not include a group of Myh6:MerCreMer mice administered tamoxifen. The authors only compared PALLD fl/fl and Myh6:MerCreMer/PALLD fl/fl mice.<br /> 4. The apoptosis assessment was performed 24 weeks after administration of tamoxifen to the Myh6:MerCreMer/PALLD fl/fl mice. However, cardiomyocyte apoptosis may have occurred much earlier if it was secondary to Myh6:MerCreMer tamoxifen-induced cardiotoxicity (or related to PALLD deletion).<br /> 5. The animal studies in Fig 3D show a DCM phenotype in mice with adult deletion of cardiomyocyte 200kDa PALLD which suggests a potential loss of function mechanism for DCM formation. However, the authors then report in Fig 6 that human DCM heart tissue samples have a ~2.5fold increase in mRNA expression of the 200kDa PALLD transcript which would suggest a possible gain of function mechanism for DCM formation. How do the authors reconcile these divergent results with regard to palladin's role in cardiomyocyte homeostasis and cardiomyopathy formation?
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This paper addresses the topic of how T cells migrate in different tissues. The authors provide experimental evidence that T cell migration in the lung is more confined than in lymph nodes and gut villi. While prior studies have started to define the way T cells migrate during normal and pathological conditions, there is still a lot to learn about the factors that control this process. Thus, the topic is significant and timely. The authors use previously acquired data with two-photon microscopy from murine tissues. They compare multiple motility parameters of T cells in lymph nodes, gut villi, and inflamed lungs. Experiments demonstrate that T cells in the lung have a particular mode of migration characterized by low speeds, back-and-forth motions, and confinement.
Strengths:<br /> Overall, this is a very well-performed study. The data presented is of excellent quality and, for the most part, supports the authors' conclusions. The imaging techniques used to track T cells in various organs and the mouse models implemented are very relevant and robust. The functional analysis of the different migration features of T cells is compelling and should be of use to the community. The conclusion that T cells use different migration modes depending on the organ appears novel. This is considered of major significance.
Weaknesses:<br /> The main weakness of the manuscript is that the study remains descriptive and comparative. It is important to analyze and describe different migration modes depending on the organ. Still, it would have been desirable for the authors to provide information on the reason for such differences. One of the striking observations is the back-and-forth motion of T cells in the lung. Searching for mechanisms underlying this unique mode of displacement would strengthen the quality of the study.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this paper, the authors propose a system for annotating and curating scientific publications in the context of interspecies host-pathogen interactions. This system, called PHI-Canto (the Pathogen-Host Interaction Community Annotation Tool), is an extension of an existing tool (called Canto). In addition, they present the development of new concepts, controlled vocabularies, and an ontology for annotating relevant aspects in this domain, called PHIPO (Pathogen-Host Interaction Phenotype Ontology).
The approach has been empirically validated by annotating ten publications. The application's source code is available, as well as the associated ontologies and vocabularies and an example of the data resulting from the annotation process.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
The authors' manuscript has several strengths. First, the authors consider multiple relevant levels of biology including genomics, transcriptomics, structural and functional neuroimaging, cognitive neuroscience, and psychological/environmental factors. Such an approach is often necessary to deconvolute the complexities of psychiatric phenotypes. The authors have taken careful steps to think about potential confounds (e.g., ancestry for PRS) and to try to define their phenotypes (e.g., psychological resilience and biological aging) as best as they can, given the data they have access to from the ABCD study. The manuscript is well written overall.
My main concerns relate to core assumptions and techniques that underlie the premise of the study. First, while there is comorbidity between AD and MDD, a causal relationship between the two (in either direction) is not established. Though MDD often predates AD, this is to be expected given MDD's high lifetime prevalence (15-20% of the general population) and typical age of onset before age 65. Because AD typically presents late in life (>65 years of age), MDD will, by definition, usually predate AD. While new onset, late life MDD is often the first presenting symptom of AD/Parkinson's disease and other neurodegenerative conditions, it is also not clear that this is the same disorder as idiopathic MDD.
To this point, two genetic tools can help us determine the biological relationship between MDD/AD, genetic correlation and Mendelian Randomization. Using the data from the MDD PRS used in this analysis, the Supplementary Table 3 from the Howard et al. 2019 paper (https://doi.org/10.1038/s41593-018-0326-7) reveals a genetic correlation of -0.041 between the two. This indicates essentially no strong relationship between the MDD/AD (perhaps even a slightly inverse relationship). Mendelian Randomization studies in addition to the Howard et al paper (https://doi.org/10.1212/WNL.0000000000010463) find no causal role for MDD towards AD and vice versa. Thus, their comorbidity is likely mediated by additional factors. Additionally, while stress contributes to AD pathophysiology, AD is strongly genetic and, given its late onset, it is unclear how genetic risk for AD would meaningfully impact the psychological resilience of a 9 to 10-year-old.
My second concern is regarding the statement "adolescents at genetic risk for AD/MDD" when describing the sample. Per Howard et al 2019 out-of-sample prediction testing, the MDD PRS used by the authors explains between 1.5-3.2% of the phenotypic variance in MDD when used on a sample such as ABCD. MDD PRS is in its infancy and cannot reliably be used to identify individuals at high risk of MDD given that even individuals in the top 10th percentile of MDD PRS have an odds ratio for depression of only ~2.4. We would expect 90 or so individuals in this cohort to fall into this group leaving significant concerns about statistical power and the potential for false positive discoveries. While the AD PRS is significantly further along compared to MDD because of AD's simpler genetic architecture, the same concerns apply as, outside of APOE, the AD PRS does not capture the majority of phenotypic variance in AD.
The authors state that they wish to examine the effects of perinatal adversity directly/indirectly on biological aging and then assess the potential effects of biological aging on resilience. The authors use of pubertal age as a measure of accelerated aging is understandable given the data available, though not ideal. There are well validated measures of biological age such as Horvath's epigenetic clock. While advanced pubertal age is technically a form of accelerated aging, the majority of pubertal age as a phenotype is not likely to be explained by perinatal adversity. Rather, a combination of unmeasured variables including genetic variation, dietary factors, environmental exposures (endocrine disrupting chemicals), and obesity that play a substantial role in determining pubertal age. Childhood stress has been shown to have relatively small effects on pubertal age (d = -0.1) (10.1037/bul0000270).
Lastly, the authors employ the use of an as of yet unpublished technique to map neurotransmitters density to structural data from neuroimaging studies. While this technique is certainly interesting, its face validity is not clear given that many of the receptor-disease associations reported in the original preprint do not line up with what we know about the biology of these disorders from strong human genetics data or current FDA approved treatments. Moreover, the authors mention "Excitation/Inhibition" imbalance but the technique used appears to only include glutamate data from one receptor type, mGluR5. This may not be an adequate measure of E/I imbalance, despite there being a statistically significant finding.
Measuring both transcriptional output from GWAS loci and gene expression correlates from MRI data is a noisy and challenging prospect. Indeed, recent research has shown poor correlation between gene expression and neurotransmitter receptor density.(https://doi.org/10.1016/j.neuroimage.2022.119671).
Thus, fundamental aspects of this manuscript including the use of MDD PRS to identify "at risk" individuals, the unclear link between AD and adolescent psychological resilience, the use of prepubertal age as a measure of biological age, and the limited conclusions that can be drawn from the gene expression and receptor density technique limits confidence in the results as presented.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors use a series of elegant methods to describe the nature of the interrelationship among CD8+ T cells and fibrocytes in the airways of COPD patients. They find an increased presence of these interactions in COPD and show that CXCL8-CXCR2 interactions are crucial for this interaction, leading to increased CD8+ T cell proliferation.
Major strengths of the work include the detailed functional experiments used to describe the nature of the CD8+ T cell - fibrocyte interaction. Another key strength is the translational approach of the work, building on clinical data and connecting back to these same clinical data. The conclusions of the authors are supported by the data. The impact of the work is significant and key to our understanding of the interrelationship between inflammation and tissue remodeling in COPD. Understanding this relationship holds strong potential for the identification of new drug targets and for the identification of patients at risk.
The derivation of the CXCL8/CXCR2 dependency is based on a limited number of COPD patients, which could be strengthened. Also, the impact of the interrelationship between CD8 cells and the fibrocytes is not fully described.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript: "Metabolic consequences of various fruit-based diets in a generalist insect species" by Olazcuaga et al., addresses an interesting question. Using an untargeted metabolomics approach, the authors study how diet generalism may have evolved versus diet specialization which is generally more commonly observed, at least in drosophila species. Using the phytophagous species Drosophila suzukii, and by directly comparing the metabolomes of fruit purees and the flies that fed on them, the authors found evidence for "metabolic generalism". Metabolic generalism means that individuals of a generalist species process all types of diet in a similar way, which is in contrast to "multi-host metabolic specialism" which entails the use of specific pathways to metabolize unique compounds of different diets. The authors find strong evidence for the first hypothesis, as they could easily detect the signature of each fruit diet in the flies. The authors then go on to speculate on the evolutionary ramifications of this for how potentially diet specializations may have evolved from diet generalism. Overall, the paper is well written, the experiments well documented, and the conclusions convincing.
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d2l.arizona.edu d2l.arizona.edu
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In my life thinking critically looks like reflecting on your past and history to guide you with your decision making in the future. There may not be an exact situation from the past that will be the answer, but there could be a scenario that is similar that you can use to help influence your future decision making skills.
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d2l.arizona.edu d2l.arizona.edu
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Using information and ethically for me pretty much sums up to, giving credit where credit is due and using data to help you with decision making. In my job we collect data from students which helps us get funding for my program. I understand that, if we are not getting positive growth in our data then we run the risk of loosing funding. So I understand the importance of data.
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d2l.arizona.edu d2l.arizona.edu
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Understand and value differences to me means, being open minded and the use of cultural relativism. To me it is incredibly important to be accepting and understanding of other people's cultures and customs. Whenever someone would acknowledge my culture I would always feel very proud of it. So I want to repay that and give the respect that all differences deserve.
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d2l.arizona.edu d2l.arizona.edu
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Communicating effectively to me just means getting the message out with the shortest amount of words with the same impact. I do a lot of presentations for my job which requires me to change the way how I talk with varying groups of kids so being able to deliver the message as short and sweet as possible is effective communication.
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openai.com openai.comDALL·E 21
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https://openai.com/product/dall-e-2
DALL·E 2 is an AI system that can create realistic images and art from a description in natural language.
Tags
Annotators
URL
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The goal of this study was to provide in situ measurements of how combined eye and body movements interact with real 3D environments to shape the statistics of retinal motion signals. To achieve this, they had human walkers navigate different natural terrains while they measured information about eyes, body, and the 3D environment. They found average flow fields that resemble the Gibsonian view of optic flow, an asymmetry between upper and lower visual fields, low velocities at the fovea, a compression of directions near the horizontal meridian, and a preponderance of vertical directions modulated by lateral gaze positions.
Strengths of the work include the methodological rigor with which the measurements were obtained. The 3D capture and motion capture systems, which have been tested and published before, are state-of-the-art. In addition, the authors used computer vision to reconstruct the 3D terrain structure from the recorded video. Together this setup makes for an exciting rig that should enable state-of-the-art measurements of eye and body movements during locomotion. The results are presented clearly and convincingly and reveal a number of interesting statistical properties (summarized above) that are a direct result of human walking behavior.
A weakness of the article concerns tying the behavioral results and statistical descriptions to insights about neural organization. Although the authors relate their findings about the statistics of retinal motion to previous literature, the implications of their findings for neural organization remain somewhat speculative and inconclusive. An efficient coding theory of visual motion would indeed suggest that some of the statistics of retinal motion patterns should be reflected in the tuning of neural populations in the visual cortex, but as is the present findings could not be convincingly tied to known findings about the neural code of vision. Thus, the behavioral results remain strong, but the link to neural organization principles appears somewhat weak.
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ung.edu ung.edu
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dispense,
to give out something, especially products, services, or amounts of money 分配、發放
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lyre
a stringed instrument of the harp class having an approximately U-shaped frame and used by the ancient Greeks especially to accompany song and recitation (https://www.merriam-webster.com/dictionary/lyre) 古希臘的七弦豎琴
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stratagems,
an artifice or trick in war for deceiving and outwitting the enemy (https://www.merriam-webster.com/dictionary/stratagem) 計謀、詭計、策略、戰略
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www.radiofrance.fr www.radiofrance.fr
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Pour aider les enseignants à accompagner ces enfants, les Auxiliaires de Vie Scolaire viennent renforcer en classe un ou plusieurs élèves, avec une grande utilité. Bien sûr, la robotique ne remplacera jamais les AVS. Mais par contre, on peut essayer de prévoir un certain nombre de qualités ou d'aptitudes pour le robot qui permettraient d'aider l'accompagnant.
DANS LE CADRE D'UE NOTE CRITIQUE POUR L1 PSYCHOLOGIE IED
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this study, Ippolito and colleagues elucidated the molecular mechanism of CMK-1 shuttling between the nucleus and cytoplasm and its function in the context of regulated thermosensation in C. elegans. This study is built on their previous work that identified a specific Nuclear Export Sequence (NES) required for CMK-1 cytoplasmic localization at 20{degree sign}C, and a specific Nuclear Localization Signal (NLS) to promote prolonged heat (28{degree sign}C)-induced CMK-1 nuclear entry. Here they show additional functional NES and NLS which counteract previously identified elements: the NLS297-307-dependent nuclear entry pathway and the S325-dependent cytoplasmic accumulation. Combined with their previous study, their work suggests a model: upon prolonged FLP neuron stimulation by noxious heat, CaM binding to CMK-1 causes CKK-1-dependent phosphorylation of T179, which in turn has a context-dependent dual effect: it is sufficient for nuclear translocation at 20{degree sign}C in an NLS71-78-dependent manner, and it promotes NES288-294-dependent nuclear export at 28{degree sign}C.
The authors thereby established a direct link between the state of a signal transduction pathway and FLP neuronal activity in response to heat stimulation. They used multiple approaches, including transgenics and reporter quantification analysis to characterize CMK-1 nucleo-cytoplasmic dynamic equilibrium. The experiments are well-designed with appropriate controls and appropriate sample sizes. The data analysis is comprehensive and revealing. The findings expand the functionally relevant intrinsic CMK-1 subcellular localization determinants. The new understanding generated in this study will appeal to readers in the fields of cell biology, signal transduction, and physiology.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In their paper Variation in thermal physiology can drive the temperature dependence of microbial community richness, Clegg and Parwar present a relatively simple phenomenological model for explaining the wide variety of empirically observed relationships between temperature and diversity in the microbial world. Previous theories such as the Metabolic theory of biodiversity (MTB) and the metabolic niche hypothesis have emphasized the role of energy through either more efficient cellular kinetics or temperature-dependent niches. This paper builds on these works by showing that if one accounts for the variation of temperature sensitivity across species, one can get a much richer set of behaviors consistent with empirical observations.
Overall, I find the manuscript quite compelling and the model presented as a very nice summary of how variability in temperature dependence, simple Arrhenius scaling, and arguments based on modern coexistence theory can be combined to explain empirical observations of species abundance distributions and temperature.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Despite high bone mineral density, increased fracture risk has been associated with T2D in humans. In this study, the authors established a model that could mimic some aspects of T2D in mice and then study bone turnover and metabolism in detail.
Strengths<br /> This is an exciting study, the methods are detailed and well done, and the results are presented coherently and support the conclusions.<br /> Previous work from Dr. Long's group over this last decade has established a requirement for glycolysis in osteoblast differentiation. They showed the requirement for glycolysis not only for the anabolic action of PTH but also as an effector downstream of Wnt signaling. Using the T2D mouse model they have generated, they test if manipulating glycolysis and oxidative phosphorylation can rescue some of the detrimental effects on bone in this model.<br /> They use several novel approaches, they use glucose-labeling studies that are relatively underutilized, and it provides some insights into defective TCA cycle. They also utilize BMSCs that have been sorted for performing single-cell sequencing studies to identify specific populations modified with T2D. Unfortunately, the results are modest and need some clarification on what these populations add to the story.<br /> The authors use two approaches: a drug (Metformin) and a number of mouse genetic models to over-express genes involved in the glycolytic pathway using Dox inducible models. The results with overexpressing HIF1 and PFKFB3 show a potential rescue of bone defects with T2D, and Glut1 overexpression does not rescue T2D-induced bone loss.
Concerns<br /> The authors have generated several overexpression models to manipulate the glycolytic pathway to recuse T2D-induced bone loss. The use of DOX in drinking water has been shown to affect mitochondrial metabolism. Did the authors control for these effects? Since both the groups of mice got the DOX in drinking water, there is internal control.<br /> Only one of the rescue experiments had control with the Chow diet. There are some studies that have shown a high-fat diet to be protective of bone loss in TID models.<br /> The use of metformin to correct metabolic dysfunction and, thereby, bone mass is an exciting result. Did the authors test to see if they had in any way rescued this phenotype because of reducing ROS levels? The decrease in OxsPhos seen with the seahorse experiments suggests there could be mitochondrial dysfunction often associated with ROS generation.<br /> All of the experiments used male mice (because STZ use and ease of T2D establishment in males). It would be better if this were made clear in the title.<br /> Is the T2D model presented really represent what is observed in humans? Some experiments to test the other factors implicated in T2D and whether those are modulated in the rescue experiments might help address this.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The underlying toxic species in C9ORF72 FTD/ALS is debated, with evidence for the contribution of both loss of function and gain of function of sense G4C2 repeat-expanded mRNAs and DRPS has been shown. The authors ask what the role - if any - of the antisense C4G2 repeat expanded mRNAs, which are equally abundant in patient brains, in producing toxicity. They convincingly show a role for these, independent of DRP expression, and distinct from sense G4C2repeat-expanded in toxicity in cell lines, neurons, and zebrafish, mediated via PKR activation. The latter is shown through increased p-eIF2alpha and reduced protein synthesis rates, associated with toxic phenotypes, rescued by PKR knockdown. The authors have achieved their aims, where the excellent data strongly support their conclusions.
The mechanism for PKR activation by antisense but sense repeat-expanded mRNAs is not examined, but the authors reasonably propose secondary structure differences in PKR activation. This could be tested in future work.
The work adds to our understanding of mechanisms of toxicity in repeat disorders, and this particular mechanism has implications for therapy via ISR modulation to reverse the effects of PKR activation.
The human data adds to the spectrum of protein-misfolding neurodegenerative diseases that show UPR/ISR activation, again with implications for therapy via ISR modulation.
Interestingly, PKR knockdown only partially rescues cell toxicity in neuronal cells, possibly reflecting other toxic mechanisms at play.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This work continues the exploration of the GspB protein as a cytosolic hub for different cell wall enzymes. In particular, this manuscript presents evidence for the direct interaction of GspB with both FtsZ and PBP4 in Staphylococcus aureus. Structural determination is provided for the N-term region of GspB alone and in complex with the small cytosolic region of PBP4 recognized by GspB.
After previously published works from the same group identifying the connection between GspB and FtsZ, and from another group providing the structural basis for the interaction between GspB and PBPs in different bacterial species; the present work provides incremental information for the S. aureus case. The work is sound, and the experimental evidence supports the presented conclusions.
The main strength of the manuscript is providing pieces of evidence of the protein-protein interaction between GspB and FtsZ and between GspB and PBP4.
However, no structural information is provided for the GspB:FtsZ complex, and the 3D structure of the N-term domain of GspB is very similar to previous ones solved for other bacteria, but with the presence of a three-residues insertion that provides flexibility to the domain, a fact that seems to be important in vivo.<br /> The complex of N-term GspB with the cytosolic micro-domain of PBP4, reveals the interactions involved in the recognition; an interaction network that is similar to the previously reported for GspB and PBPs in bacillus subtilis and in Streptococcus pneumonia.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This study examined the relationship between dopamine synthesis capacity, working memory, impulsivity, and spontaneous eye blink rate. The rationale for the study is sound and well-articulated given the results of prior studies suggesting relations between dopaminergic measures and these behavioral measures. Understanding these relationships is important both for understanding the neural and neurochemical correlates of behavioral traits, but also because it has been proposed that these measures might be used as a proxy for dopamine synthesis capacity, which is extremely expensive to collect and requires exposure to radiation. The study used appropriate methods and a major strength is that it was performed in a larger sample than is typical for PET studies, which are typically underpowered due to the expense of using radioligands. Critically, the study did not find evidence for associations. Although the results can be seen as disappointing in that they failed to confirm hypotheses, the findings nevertheless have substantial implications for the field. Specifically, the results argue against the use of these behavioral constructs as a proxy for dopamine synthesis activity. As such, the findings provide a critical corrective for prior conclusions that were derived from past smaller studies.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This is an interesting study that seeks to deorphanize Tango2, a protein linked to muscle dysfunction but with no known function. It reveals that Tango2 primarily co-localizes with mitochondria, and its loss impacts mitochondrial homeostasis. Tango2-depleted cells also accumulate LDs. Lipidomic analysis indicated a partial depletion of diacyl lipids including PA in Tango2-depleted cells, and an accumulation of lyso-lipids such as LPA. The proposed model suggests that Tango2 plays a role in lipid metabolism, potentially in acyl-CoA trafficking and or delivery to lyso-lipids to generate diacyl-lipids for mitochondrial homeostasis, which is defective in tango2-deficient diseases like rhabdomyslosis. In general, this is a well-conducted and potentially important study. The first section which deals with Tango2 localization and profiling of cellular changes in Tango2-depleted cells is well conducted. However, the latter half which seeks to understand how Tango2 loss impacts lipid homeostasis is more preliminary. Lyso-lipids like LPA are definitely altered with tango2 loss, but additional work is necessary to understand whether this is due to increased lyso-lipid synthesis, a block in their acylation, or some combination of factors. Delineating these possibilities will significantly enhance this study.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Dell'Amico and colleagues examine a C-terminal truncating mutation of WDR62, a gene identified as the 2nd most frequent cause of primary microcephaly. The authors generate neural progenitor cells and neurons from patient-derived IPSCs to examine the cell biological phenotypes of the truncation. This reveals the localization of WDR62 in the Golgi apparatus during interphase and suggests that shuttling from the GA to the spindle poles could be a potential mechanism underlying the effects of WDR62 truncation on cortical development.
Whereas these model systems are useful to study certain cell biological aspects of mutated cells, they do not fully recapitulate all features of the cortical development that the authors study. This model system lacks polarity of the tissue, which is important for a correct cell division of radial glia, which in turn is the key process impaired in microcephaly. Together with the inherent heterogeneity of the differentiation protocols, this poses a major weakness to the authors' approaches. On the other hand, the authors' system is well-suited for the analysis of co-localization and they show compelling evidence of the localization of WDR62 to the GA in interphase, which is the main strength of the study. These data are corroborated by immunostainings in fetal human tissue. Minor experiments are still needed to show a direct interaction of WDR62 with GA proteins and to further assess by immunofluorescence the GA-WDR62 co-localization in the radial glia of fetal human samples. Further, the author's interpretation that premature neurogenesis is not occurring in their system should be better supported by additional immunostaining. Finally, the manuscript is well written and the methods are adequately explained.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors attempt to develop an allele-specific editing approach targeting RHO-T17M mutation for potential therapeutic use to treat the mutation associated with autosomal dominant retinitis pigmentosa.
1) The authors reported three sgRNAs for the RHO T17M allele for verification. It would be helpful to describe details of the discovery phase of these sgRNAs, including design, in silico predictions, inclusion criteria, off-target analysis, etc.
2) The authors claim that the targeted gene-editing efficiencies are dose-dependent. However, data were presented from only one mouse for the 5x108 dose group (line 231-237), which might need more explanation.
3) With respect to Fig. 4C, the flat-mount retina is not representative. A better image of flat-mount of retina is preferred.
4) With respect to Fig. 6B & 6C, it seems that T17M protein and RHO-5m protein are likely detected in both cytoplasm and plasma membrane rather than being limited to the cytoplasm alone.
5) The therapeutic efficacy benefit should be supported by data of photoreceptor function and cell preservation after treatment. It is be better to include two more control groups, namely wild-type mice and untreated mutant mice, which may help evaluate improved response after treatment.
6) The mouse lines are confusing. Did the authors generate three lines of mice, including RHOwt/hum, Mut-RHOwt/hum, RHOhum/m-hum mice? Did the authors use the Rhohum/m-hum mice for verification of cutting efficiencies, whereas they use the other two lines of mice for rescue experiments? The authors should clarify.
7) Mut-RHOwt/hum mice have previously been reported to have fundus pigment abnormalities, so the fundus should be examined after rescue. The expression of Rho-5M mRNA was reduced in vitro. Was the expression of RHO mRNA also down regulated after rescue as well as in vitro? Did the subretinal injection of GFP spread to the whole retina? This can be determined with retinal flat mount or panretinal staining using GFP labeling. The authors showed that the cell numbers in the ONL were increased in the treatment group compared with the control group at 9 mpi. Were the other nuclear layers or plexiform layer also affected? Did the other retinal cells develop normally? Figure 8 showed retinal functions with AAV-based SaCas9/17-Sg2 in Mut-Rhowt/hum mice. ERG of Mut-Rhowt/hum mice without treatment are also needed.
The efficiency and safety of RHO T17M allele-specific editing in this paper are well supported by in vitro and in vivo experiments.
The fundamental basis of the study design should be clearly stated, ie which truncation variants in RHO cause disease or not. It is reported that truncation variants occurring before K296 are likely benign, which should be mentioned. This is the key starting point for this kind of study and is not limited to RHO. but as an allele-specific gene editing approach as a potential therapy for dominant mutations in any gene for which heterozygous loss-of-function is tolerated in the whole gene or in part of the gene (mostly at N-terminals). Apart from RHO, in fact, N-terminal truncating variants in several other IRD associated genes have been reported to be benign in heterozygotes, including CRX, TOPORS, RP1, etc. This study verified the efficiency and safety of this approach based on both patient derived iPSC and humanized animal models which are unique compared with other studies on RHO.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this paper, Pose-Méndez and colleagues have investigated the lifelong ability of zebrafish for functional Purkinje cell regeneration after selective ablation. Previous studies have determined that the adult zebrafish cerebellum lacks the capacity to regenerate Purkinje cells after traumatic injury. The authors use an elegant approach to determine whether selective ablation of Purkinje cells, a scenario closer to neurodegenerative disease, would allow for regeneration. The overall message is, that Purkinje cell regeneration is accomplished at every age after targeted ablation. The authors find in a series of well-executed functional and behavioral experiments that selective loss of Purkinje cells leads to a change in neuronal circuit activity and behaviors. During the regeneration process and interestingly before the full recovery of Purkinje cell numbers compared to controls neuronal activity as well as behaviors are recovered.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
In this elegant work, the authors investigated dopamine release (measured by dLight sensor fiber photometry) in the nucleus accumbens shell, in response to salient luminance change. They show that abrupt visual stimuli - including stimuli not detectable by the human eye - can evoke robust dopamine release in the accumbens shell.
The fact that dopamine signals can be evoked by salient sensory stimuli is not itself novel, but the paper manages to make several important and new findings:
1. The authors show that the dopamine signal is not related to the level of threat evoked by the visual stimuli. <br /> 2. They provide important detail about the stimuli parameters relevant to dopamine release. For instance, they show that the rate of luminance change (or abruptness) is a key factor in evoking dopamine responses.<br /> 3. They show that robust dopamine responses can be evoked by visual stimuli of low intensity, including stimuli not perceptible by the human eye.<br /> 4. They show that these dopamine responses can be evoked by all wavelengths in the visible spectrum (with some higher sensitivity at certain wavelengths).<br /> 5. Finally, by recording dopamine responses in two knockout mice strains, the authors show that the light-evoked dopamine release critically relies on rod and cone photoreceptors, but not melanopsin phototransduction.
These results add to a series of recent findings showing that dopamine signals are not restricted to the encoding of reward prediction error, but instead contribute to signaling environmental changes more broadly. The study has been skillfully executed, the results are clear and appropriately analyzed, and the manuscript is very well written. Although the work did not include control mice lacking the dLight sensor, the fact that light-evoked dopamine responses were not observed in mice lacking cone + rod phototransduction is strong evidence that the fiberphotometry signals were not due to direct light artifacts.
Comment/concerns are minor:
1. The authors show that the dopamine response evoked by a brief visual stimulus is drastically reduced when the visual stimulus is repeated in rapid succession (stimulus train). The authors interpret this as evidence for the HABITUATION of this light-evoked dopamine release. An alternative explanation is that it is the prediction of the stimulus that is responsible for canceling the dopamine response (i.e. sensory prediction error). The authors should discuss this alternative explanation for this finding.
2. Although the study largely focuses on dopamine responses to visual stimuli, the results are largely consistent with previous studies showing dopamine signals encoding value-neutral changes in sensory inputs (i.e. sensory prediction errors) in different modalities (taste or odors; cf. Takahashi et al., 2017, Neuron; Howard & Kahnt, 2018, Nat. Comm.). The authors might want to cite those papers (note that I am not affiliated with those papers).
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
This study adds value in the relatively new field, specifically in the topic of ET-B receptor. In this study the authors provide a new structure in ET-B receptor that might be beneficial to the development of ET-B agonist. However, from the clinical and physiological point of view, the manuscript did not provide sufficient evidence in its current form.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Ribonucleotide reductase (RNR) is crucial for de novo synthesis of the dNTP building blocks needed for DNA synthesis and is essential in nearly all organisms. In the current study, all three E. coli RNRs have been removed and the essential function of the enzyme is bypassed by the introduction of an exogenous deoxyribonucleoside kinase that enables dNTP production via salvage synthesis. This leads to a complete dependency on exogenously supplied deoxyribonucleosides (dNs), loss of control of dNTP regulation, and a highly increased mutation rate. The bacteria could also grow with only supplied deoxycytidine (and no other dNs), indicating that all dNTPs could be synthesized from deoxycytidine. An evolutionary analysis of the recombinant E. coli strain grown in multiple generations showed that mutations accumulated in genes involved in the catabolism of deoxycytidine and deoxyribose-1-P, supporting a model that all the other deoxyribonucleosides can be produced by a phosphorylase using nucleobases and deoxyribose-1-P as substrates and that the deoxycytidine (besides being a precursor of dCTP) could be a substrate to produce the deoxyribose-1-P needed by the phosphorylase working in the opposite direction.
The story is very interesting with novel findings, and the experiments are well performed. There are a few missing pieces of information, but on the other hand, it is many steps to cover if everything is going to be shown in a single paper and I came to the conclusion that the data is enough at this stage. One of the missing points for future research is to check what happens with the dNTP pools. RNR is a very important enzyme to control the dNTP levels and it is likely that it is unbalanced dNTP pools that lead to the increased mutation rates. However, it would be interesting to really measure the dNTP pools and connect them to the mutations reported. Another missing piece is to identify which nucleoside phosphorylase is involved and investigate its substrate specificity to better understand why the cells can live on deoxycytidine but not other dNs.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The aim of this article was to create a biologically plausible model of decision-making that can both represent a choice's value and reproduce winner-take-all ramping behavior that determines the choice, two fundamental components of value-based decision-making. Both of these aspects have been studied and modeled independently but empirical studies have found that single neurons can switch between both of the aspects (i.e., from representing value to winner-take-all ramping behavior) in ways that are not well described by current biological plausible models of decision making.
The current article provides a thorough investigation of a new model (the local disinhibition decision model; LDDM) that has the goal of combining value representations and winner-takes-all ramping dynamics related to choice. Their model uses biologically plausible disinhibition to control the levels of inhibition in a local network of simulated neurons. Through a careful series of simulation experiments, they demonstrate that their network can first represent the value of different options, then switch to winner-takes-all ramping dynamics when a choice needs to be made. They further demonstrate that their single model reproduces key components of value-based and winner-takes-all dynamics found in both neural and behavioral data. They additionally conduct simulation studies to demonstrate that recurrent excitatory properties in their network produce value-persistence behavior that could be related to memory. They end by conducting a careful simulation study of the influence of GABA agonists that provide clear and testable predictions of their proposed role of inhibition in the neural processes that underlie decision-making. This last piece is especially important as it provides a clear set of predictions and experiments to help support or falsify their model.
There are overall many strengths to this paper. As the authors note, current network models do not explain both value-based and ramping-like decision-making properties. Their thorough simulation studies and their validation against empirical neural and behavioral data will be of strong interest to neuroscientists and psychologists interested in value-based decision-making. The simulations related to persistence and the GABA-agonist experiments they propose also provide very clear guidelines for future research that would help advance the field of decision-making research.
Although the methods and model were generally clear, there was a fair amount of emphasis on the role of recurrence in the LDDM, but very little evidence that recurrence was important or necessary for any of the empirical data examined. The authors do demonstrate the importance of recurrence in some of their simulation studies (particularly in their studies of persistence), but these would need to be compared against empirical data to be validated. Nevertheless, the model and thorough simulation investigations will likely help develop more precise theories of value-based decision-making.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors made an applaudable attempt to identify druggable cryptic pockets and address a controversy regarding a pH switch of a very large system of significant biological and Pharmaceutical interest. Due to the size of the system and uncertainty in the membrane interactions/curvature the draft produces etc, it is a nontrivial task. By using a previously validated mixed solvent (i.e., benzene mapping) protocol, the authors were able to analyze the potential pockets in the entire system. This is big technical advance and the protocol can be used by other works in the field for studying cryptic pockets.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors want to capture the dynamics of CML therapy with TKI and understand why some patients fail to respond to therapy (primary resistance). They develop a mathematical model of hematopoiesis that includes stem cells, progenitor cells, and mature cells linked through feedback mechanisms. They explore parameter space using sophisticated algorithms to reduce this parameter space and the potential models to one final model and then apply it to chronic myeloid leukemia in the chronic phase under therapy with a tyrosine kinase inhibitor. The novelty in the model is the feedback mechanism introduced and the concomitant animal model data to understand the parameters.
The model is tractable and yet captures important physiologic aspects of hematopoiesis that have not been explored previously in CML. The animal data to validate it is also quite important. Finally, the application of the model to clinical data illustrates its applicability to real clinical scenarios and provides interesting insights.
One concern is whether the short-term transplantation experiments truly reflect the steady state of hematopoiesis and how CML develops in humans.
It is possible that the model can be applied to other hematologic conditions such as myeloproliferative disorders since one would expect the dynamics and interactions to be similar.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
Throughout the manuscript, the authors aim to distinguish signal from the lack of it. All conclusions depend on the success of this process. In such an endeavor, the sensitivity of the applied methods is critical. Thus, the authors must use the most sensitive tools to draw meaningful conclusions. The latest iGluSnFR has amazing sensitivity allowing the detection of single AP-evoked responses. This is not the case for vGpH, which requires hundred APs to get a meaningful signal. Similar, synthetic Ca2+ dyes have much better dynamic range, linearity and sensitivity compared to GCaMP6f.
The rate of silent boutons at 2 mM [Ca2+]e is lower for a single AP compared to 20 or 200 APs. The overall failure rate cannot be increased with increasing the number of APs. This clearly indicates a technical issue (e.g. insufficient sensitivity of vGpH and GCaMP6f).
The authors used three different measuring tools and used three different stimulation protocols, making the interpretation of the data challenging. It is impossible to tell how the failure rate changes from 1 to 20 APs without knowing the release probability, the pool size, depletion, recovery of SVs, and facilitation. These are all unknown.
The last experiment with the GABAB agonist has little novelty in its present form. The authors demonstrate that GABAB agonism increases the rate of silent terminals. The interesting issue would be to reveal how the effect of GABAB activation depends on the [Ca2+]e. This information is essential to see whether there is indeed a shoulder in its effectiveness curve.
The authors refer to a theoretical set-point in [Ca2+]e below which the function of the terminals is fundamentally different. From the presented experiments, the reviewer does not see any data that is inconsistent with a continuum. 'Thus, as with Ca2+ influx, SV recycling is modulated in an all-or-none manner by modest changes in [Ca2+]e around the physiological set point.' This statement is not supported by the data. The reviewer cannot see a set point.
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www.medrxiv.org www.medrxiv.org
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Reviewer #2 (Public Review):
In this study, Bayliss et al. built a machine learning algorithm that predicts which country an isolate of Salmonella Enteritidis has come from based on its genome sequence. The study used S. Enteritidis isolates taken from clinical infections in the UK with recently reported travel, with the recent travel location being assumed as the source of infection.
The reason for developing this type of algorithm is to use it for source attribution in the case of gastroenteritis cases caused by imported food or cases of gastroenteritis picked up during travel overseas. S. Enteritidis is a major cause of gastroenteritis worldwide. Its transmission is tied in with the food chain, and understanding where it travels and how is key to reducing the burden of these infections. While a country's efforts to reduce the burden of these bacteria within its own borders can have tremendous benefits, imported food can still introduce contaminated meat and produce, and these have indeed become larger proportional risks following control efforts in the UK.
S. Enteritidis shows strong geographical substructuring across its phylogenetic tree. Traditional phylogenetic analysis is time-consuming (particularly to perform repeatedly on a routine basis) and required highly skilled staff to perform. Machine learning should be able to identify genetic markers linked to clades typically found in a single location, without the need to build and interpret a phylogenetic tree.
There is some nice methods development work in this paper, with the employment of a hierarchical structure to the ML modelling pipeline and the use of an array of classifier, resampler, feature selection and parameter optimisation techniques to increase accuracy.
However, the main strength of this paper is how well tailored the model is to a real world use case. Many groups are applying machine learning to genomic data, but often not with a clearly defined use case or realistic training and testing conditions. The results begin by giving the reader an understanding of the current state of this work in a UK context, where all clinically reported cases of Salmonella are sequenced and when appropriate, travel history is recorded. The algorithm is designed to fit into this existing practise and thought has been put into how this would be operationalised. For example, the authors have shown that this work can truly be done in real-time, by developing an algorithm that works directly on raw reads and takes <4 mins to run. A great touch in this work was determining the time horizon over which the model should be retrained to keep up with contemporary geographic distributions of this pathogen. The time horizon itself may not be highly generalizable in genomic epidemiology, but the methods provided make it easier for others to make the same assessment for their pathogen and use case.
A weakness of the work is the areas where predictions are not as accurate, but this relates to the extent of pathogen sequencing today rather than the method itself. Countries with less accurate predictions are ones which few people return from with an infection and if they do, it tends to be a different strain each time, making building an accurate algorithm for these cases impossible without denser sampling outside of clinical infections or more sequencing of infections occurring in other countries. Without proofs of concept like this, there is less of a strong economic argument to justify these investments. Therefore this work represents an important step in demonstrating the feasibility of the method itself and the value in gathering more data. In contrast, a major strength of this work is that it uses data collected routinely from existing practice in the UK, rather than a bespoke sampling strategy that may not be realistic for routine public health. A comparison of the collection to NCBI also found this sampling to be less biased by specific outbreaks of interest, which is encouraging.
The training dataset appears to be only based on infections acquired overseas, while I suspect the model would be more useful in investigating infections due to imported contaminated food. An unresolved question from this work is therefore whether the source of travel-acquired infections and infections caused by food imported from the same places is the same, or whether exported vs domestically consumed food around the world is treated differently in important ways that would affect the relative prevalence and success of strains in causing infections. Looking at clinical infections also may bias Salmonella to those that cause more severe forms of infection, as many people don't report to a doctor when they have food poisoning. The large egg-related outbreak that did not feature much at all in the UKHSA dataset is potentially a nice example of this.
The low accuracy on countries with low infection numbers and high genetic diversity indicates that these algorithms would likely become less accurate over time if food safety is improved, and that individual countries could avoid being confidently attributed as a source of infection by eliminating or controlling major circulating foodborne clones. More clearly communicating when a prediction is uncertain could be helpful in dealing with isolates from countries where it is hard to make a determination.
One final limitation I see is the exclusion of UK Salmonella isolates - in cases where it is uncertain whether a Salmonella infection is due to import or not, it does not seem possible to make this assessment using the ML tool. This also limits the utility of the tool for other countries that might also benefit.
The authors have done an excellent job of demonstrating the feasibility of this approach and honing their machine learning workflow to the specific demands of the task. The work presents a clear and well thought out use case with the overall performance of the algorithm broken down into test cases where the algorithm is successful and unsuccessful which provide useful insight into what we can expect from the performance of these approaches.
Finding a way to better communicate when the source of an outbreak is unclear due to poor representation of a clade or a clade that is found in many countries would be a valuable extension of this work in the future, but as it is the results represent a promising starting point for initiating investigations into the source of Salmonella infections.
Diarrheal disease is a huge health burden worldwide. Previous work to lower the burden of these infections has shown that targeted interventions can make a substantial difference to the burden of disease and success of clonal outbreaks. The availability of a tool that can be used routinely to assess the most likely overseas origin of an infection could potentially highlight previously unrecognised outbreaks or areas of suddenly increased importation rate. In turn, this could lead to better investigations and targeted improvement of food security.
This paper provides an excellent case for the value of collecting recent travel history and including it in metadata for pathogen genomic data. If this were done in more countries with different patterns of travel and the data could be shared, this would provide a valuable global resource and start to capture the flow of strains internationally.
I am curious about the implications of being better able to attribute clinical gastroenteritis cases in the UK (and elsewhere) to food imported or travel to specific countries with respect to trade and regulation. This is well outside the scope of the paper, however the ability to capture isolates commonly picked up from food around the world without the cooperation of these countries raises interesting issues, particularly when factoring in the authors' scenarios of the true country of origin being obscured by uneven travel patterns and complex food supply networks.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The mechanism for early-onset osteoporosis (EOOP) is not well understood. The authors performed PLS3 knockout and characterized its bone phenotype in a rat model. This provides a very useful tool for studying EOOP and the potential treatment for EOOP. The authors did a very nice job of characterizing the phenotype including the assessments of bone turnover markers, bone histomorphometric analyses, and bone biomechanical tests. The results from these assessments led to the conclusion that this PLS3 knockout rat model mimics the human EOOP. In addition, treatment with currently available drugs for osteoporosis is effective in this EOOP model. These results support further clinical investigation of anti-osteoporosis drugs for EOOP management.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The manuscript at hand by Sharma et al. presents new data on neurons of the stellate ganglia that are relevant for autonomic control of the heart. The authors identify stellate ganglionic neurons (SGN) that innervate the heart by retrograde tracing techniques and differentiate them from SGN neurons innervating other organs and tissues (mostly paw is used as a control). They subsequently employ single-cell RNAseq and morphological and functional (electrophysiological) studies. Their main finding is the identification of 3 SGN subtypes that they were further able to stratify into high and low neuropeptide Y cells. These subpopulations differ with regard to gene expression and action potential generation indicating different electrophysiological properties and different roles in the sympathoexcitation of the heart. They validate these findings by in vivo experiments where electrical stimulation of stellate ganglia after NPY-expressing neurons was depleted and find that heart rate change was lower under stimulation with high frequencies for NPY-depleted mice. The research question is very relevant and might have important therapeutic consequences for patients with cardiac diseases. The paper is written clearly. The methods applied are elegant and appropriate and the data support the conclusion.
The authors do report on some experiments in which stellate ganglion was used. Viral administration and physiological studies were performed on the right, while RNA sequencing was done from the right and left stellate ganglion. As there are physiological lateral differences between the effects of the left and right stellate ganglion, it would be useful to thoroughly report which side was used for which experiment throughout the manuscript and to discuss whether any lateral differences are relevant for the obtained results and conclusions.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The authors develop statistical tests for assessing whether two hemispheres of the Drosophila larval brain are bilaterally symmetric, and more generally to develop a framework for comparisons of connectomes. The study is organized in order of increasing complexity of the statistical test, beginning with a simple test of whether or not the two sides of the brain have equal connection density. A more sophisticated approach is applied to a model in which neurons are partitioned into groups defined by preexisting known cell types on the left and right hemispheres and densities are allowed to vary between groups (a stochastic block model). A correction is included for an overall difference in density between hemispheres. Finally, analyses are applied to assess which cell types contribute to differences in the larval connectome. This identifies Kenyon cells as particularly distinct - a density-corrected stochastic block model with Kenyon cells removed results in no significant bilateral asymmetry. Results are also compared across different choices for thresholding of connection weights.
This manuscript tackles an interesting and timely problem. The analyses are largely straightforward applications of standard hypothesis tests for binomially distributed random variables. However, the observation that a density correction is needed to account for the two hemispheres' connection probabilities, and that a stochastic block model is sufficient to describe these probabilities, with the exception of the Kenyon cells, is interesting and makes more precise the notion of bilateral symmetry, at least at the level of connection probabilities, than previous approaches.
There are still several questions that remain about the generality of the results. The first concerns assumptions about the generative model for the graph. As the authors acknowledge, an Erdos-Renyi random network is a strong simplifying assumption. In particular, independent edge weights may be a restrictive model of connectome data given the broad degree distribution, spatial dependencies, and other features that characterize biological connectivity. A second question concerns the issue of statistical power. After partitioning neurons into groups, the most significant difference in connection probabilities comes from Kenyon cells, with the smallest p-value in the density-corrected comparison coming from KC-to-KC connections (Fig. 4B). However, KCs represent a large group of neurons, and the KC-to-KC connection probability is among the highest in the larval brain (Fig. 3B), raising the question of whether the observation of a significant difference specifically for these neurons is simply due to increased power. Third, connection density is only one of the many graph features that may be relevant for evaluating connectome similarity.
In total, although the analyses are straightforward, the study represents a first step toward the evaluation of connectome similarity and should spur further work in this important direction.
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www.biorxiv.org www.biorxiv.org
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Reviewer #2 (Public Review):
The two new micropeptides are well characterized in the manuscript and appear to be functionally important with some chromatin-level consequences of their loss (which can be either direct or indirect), but the finding that lincRNA sequences encode micropeptides is not novel, and the two described in the paper appear to be zebrafish-specific and their function was tested only in zebrafish, which limits the interest in these genes. The use of ribosome profile data along behavioral screening to identify micropeptides is interesting and important, but the scope of the screen, the candidates selected for testing, etc. are not clear enough as presented. The ChIP-seq analysis of the new proteins is very interesting but is not described in any detail. Overall, the experimental part is well designed and the phenotypes reported by the authors appear to be strong and convincing, but the mechanistic understanding of what the two new proteins do and how, and the general interest in the results given the current scope of understanding of micropeptide is limited.
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Reviewer #2 (Public Review):
In this work, the authors have carried out an extensive and highly granular survey of Mycobacterium ulcerans carriage by possums who are living on the outskirts of Melbourne Australia, in areas that are known hot spots for cases of Buruli ulcer (BU). The work is the culmination of many years of endeavour by this team, who first identified that the faeces of possums can be highly positive for M. ulcerans DNA, genetically linked to the strains found in BU patients who live in, or have visited, the area.
Surveys across two seasons were performed. Based on qPCR data to identify M. ulcerans carriage, spatial mapping of this, and BU case data, a statistical model was generated using data from the Mornington Peninsula that was better predicted than a null model. This statistical model was then validated using a second independent site at Geelong. As a result of this data, there can now be little doubt that possums play a vital role in the transmission cycles of BU in the region, and will allow mitigation strategies to be designed and tested. As BU is a necrotising skin disease that can cause disability and permanent disfiguration even in a high-resource setting such as Australia, such approaches are urgently needed.
Strengths:
The scale (both in terms of geographic reach/granularity and time) of the surveillance effort to understand the distribution of M. ulcerans DNA in the local possum population is unprecedented.
Since BU is a notifiable disease in Australia, the researchers have access to comprehensive clinical information across the study period.
The statistical model developed had a strongly positive influence over the ability to predict where BU cases will arise, over areas with a small radius (several km) which is the first time this has been achieved. The process by which this model was developed and validated seems robust.
Weaknesses:
In their model, the authors have used an assumed "exposure window" for when patients were infected with M. ulcerans in the Mornington Peninsula. Correctly defining, and assigning, this is absolutely critical to the accuracy of the statistical model, as is "blinding" of researchers assigning mesh boxes to patients to the results of surveillance data (and vice versa). These aspects are not fully clear in the current version. Furthermore, the effects on the model of changing these assumptions are not discussed.
The presence of M. ulcerans DNA in possum excreta and in patient samples is defined by qPCR for IS2404, a multicopy insertion sequence. Greater justification for using this as the sole marker is required, as this insertion sequence is also present in other mycolactone-producing mycobacteria. Moreover, some samples were claimed to be 'positive' with Ct values of 40 without justification for using this value (such as standard curves).
Comparing the summer and winter surveys at the Mornington Peninsula, the distribution of M. ulcerans positive excreta appears to have changed quite substantially, especially given that the possums are reported to be highly territorial with a range of only 100m. This version of the manuscript does not formally compare these spatial distributions, only the averages. Such an analysis would help understand if it is the possums that are moving, whether the possums undergo 'waves' of carriage (or indeed any other explanation), or if these apparent differences are down to chance.
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Reviewer #2 (Public Review):
In their manuscript, Francou and colleagues study the delamination of epiblast cells into the mesodermal layers using live imaging of mouse embryos cultured ex vivo. By segmenting the apical area of delaminating cells, they quantify extensively the dynamic behavior of delaminating cells. Using immunostaining and crumbs2 mutants, they propose that apical constriction of cells results from pulsed contractions, which could be guided by crumbs2 signals.
The manuscript is interesting and provides extremely valuable data for our understanding of mouse gastrulation. Occasionally, the manuscript can be a bit confusing and contains a few inaccuracies. However, the main issues I have are with some of the interpretations from the authors, which may be incorrect due to limited time resolution (with a 5 min time resolution that was used, it might be difficult to distinguish pulses from measurement noise) and the analysis of immunostaining data, which would require more rigorous quantification.
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Reviewer #2 (Public Review):
This manuscript documents the study of the transcriptome of Borrelia burgdorferi at 1, 2, 3 and 4 days post-feeding in nymphs of Ixodes scapularis. The authors use antibody-based pull-downs to separate bacteria from tick and mouse cells to perform an enrichment. The data presented support that the transcriptome of B. burgdorferi changes over time in the tick. This work is important as until now, only limited information on specific genes had been collected. This is the first study of its kind and is valuable for the field.
The manuscript is overall well written and easy to follow. The data are compelling and support the conclusions.
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Reviewer #2 (Public Review):
Mitochondria are essential cellular organelles that generate ATPs as the energy source for maintaining regular cellular functions. However, the degradation of sperm-borne mitochondria after fertilization is a conserved event known as mitophagy to ensure the exclusively maternal inheritance of the mitochondrial DNA genome. Defects on post-fertilization sperm mitophagy will lead to fatal consequences in patients. Therefore, understanding the cellular and molecular regulation of the post-fertilization sperm mitophagy process is critically important. In this study, Zuidema et. al applied mass spectrometry in conjunction with a porcine cell-free system to identify potential autophagic cofactors involved in post-fertilization sperm mitophagy. They identified a list of 185 proteins that might be candidates for mitophagy determinants (or their co-factors). Despite the fact that 6 (out of 185) proteins were further studied, based on their known functions, using a porcine cell-free system in conjunction with immunocytochemistry and Western blotting, to characterize the localization and modification changes these proteins, no further functional validation experiments were performed. Nevertheless, the data presented in the current study is of great interest and could be important for future studies in this field.
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Reviewer #2 (Public Review):
The work presented in this manuscript focuses on the role of Cylicins in spermiogenesis and the consequences of their absence on infertility. The manuscript is presented in two parts: the first part studies the absence of Cylicins from KO mouse models and shows in mice that both isoforms of Cylicins are necessary for normal spermiogenesis. The evaluation of double heterozygotes is particularly useful for the second part which looks at the presence of mutations in these genes in a cohort of infertile men. A patient with two hemizygous/heterozygous mutations in the CYLC1 and 2 genes, respectively, was identified for the first time and the results obtained with the KO models support the hypothesis of the pathogenicity of the mutations.
In general, the experiments are perfectly performed and the results are clear. Numerous techniques in the state of the art in male reproduction are used to obtain high-quality phenotyping of the mouse models.
The discovery of two concomitant mutations in an infertile patient is very interesting and the work carried out on mice allows supporting that an absence of CYLC1 and a heterozygous mutation of CYLC2 could lead to a phenotype of complete infertility. However, as the mutation on CYLC2 is not identified as pathogenic, the pathogenicity of this mutation remains in question (the authors note this point in the discussion). It would be interesting to see if the mutated amino acid is conserved between different species. In mice, the authors have shown the importance of these proteins on the morphology of the acrosome. What about in humans?
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Reviewer #2 (Public Review):
The manuscript by Gordon-Fennell et al. presents an open-source platform for the analysis of behavior in a head-fixed apparatus (termed OHRBETS). In addition to providing instruction on how to assemble and implement the apparatus itself, the authors validate its use across a set of procedures broadly relevant to the field of behavioral neuroscience - including operant conditioning and fluid consumption protocols run in conjunction with optical manipulation and/or recording of neural activity.
The manuscript is comprehensive and clearly very strong. It also has the potential to have a broad impact in the field as many labs start to move towards effective head-fixed behavior. I also appreciate the fact that this manuscript includes a range of very strong behavioral tests - including experiments where several reinforcer options are available. This could be used for studies assessing taste, preference, reinforcer value, etc. Overall, the manuscript is impactful and my enthusiasm for it is high.
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