- Nov 2022
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
BAX has been shown to translocate to lysosomes where it is suggested to trigger LMP and cell death under different pathophysiological conditions, including Parkinson’s disease, oxidative stress, and autophagic cell death (35–37). To assess BAX translocation to the lysosomal membrane and its colocalization with RECS1, we detected active BAX using the 6A7 conformational antibody. Analysis of RECS1 (using the Flag antibody) and the distribution of the lysosomal protein LAMP-2 in MEFs indicated that under basal conditions (no RECS1), BAX remained mainly cytosolic (fig. S4H). However, BAX colocalized with RECS1 in LAMP-2–positive vesicles following RECS1 induction (Fig. 3, E to G). After CQ treatment, BAX was redistributed into large LAMP-2–positive vesicles, an effect that was dependent on RECS1 expression (Fig. 3E). Active BAX was present preferentially in Flag-RECS1–positive lysosomes in cells treated with CQ (Fig. 3, F and G). Together, these results suggest that RECS1 induces cell death through LMP in response to lysosomal stress, correlating with the translocation of BAX to lysosomes
Overexpression of RECS1 in CQ-stressed cells causes LMP and translocation of BAX to the lysosome, which induces cell death. BAX is a proapoptotic protein.
-
- Sep 2021
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
After ablation, we observed a 95% reduction in time spent exploring the open arm of the EPM and a 57% increase in duration of the immobility time in the FST
These findings validate the effectiveness of TH-IR ablation by 6-OHDA, as a decrease in time spent in the open arm of the EPM is associated with increased anxiety, and an increase in immobility time in the FST is associated with a depressed state. These results are not surprising as it is expected that a halt in the synthesis of dopamine (the feel-good transmitter) would increase anxiety and depression.
-
Long-day exposure produced the opposite effects
For rats, nocturnal mammals, increased photoperiod exposure is a stressor. Consequently, in both the EPM and FST, rats exhibit more depressive/anxious behaviors following long photoperiod exposure. In the EPM test, these rats spend less time in the open arm, and in the FST, they give up swimming and become almost immobile much sooner than the control group. For the short-day exposure group, the rats have more open arm activity, and in the FST persevere for longer, indicating reduced anxiety relative to the control group.
-
Assays of CRF in the CSF and corticosterone in the plasma confirmed this to be the case (Fig. 4D).
Panel D of Figure 4 shows that CSF levels of CRF and plasma levels of corticosterone significantly decrease following short photoperiod exposure. In panel B, short photoperiod exposure results in elevated coexpression of D2R and SST2/4R. These findings support the hypothesis that increased coexpression of D2R and SST2/4R has inhibitory effects on CRF neurons of the third ventricle.
-
These results demonstrate that transmitter respecification is not achieved by translation from preexisting transcripts and involves de novo induction of TH or SST mRNA
The experimenters' measurements of mRNA expression are used to determine whether transmitter respecification is resulting from new transcription or preexisting transcription. If transmitter respecification is resulting from preexisting transcripts, TH and SST mRNA would already be present in the cytosol and only following exposure to a certain photoperiod condition, translational machinery would translate that existing mRNA. Thus, if the source is preexisting mRNA, then we should not observe TH and SST mRNA counts follow numbers of TH and SST neurons, and instead mRNA levels should be unchanged. The fact that the experimenters are observing that mRNA levels follow TH and SST neuron count demonstrates that the photoperiod exposure condition is inducing de novo transcription, rather than direct translation of preexisting transcripts.
-
Newly expressing TH-IR neurons induced through short-day photoperiod exposure coexpressed additional dopaminergic markers (3), VMAT2 (fig. S6), and the dopamine transporter, DAT (fig. S7).
Because one role of VMAT2 is to package dopamine from the cytosol into synaptic vesicles for their release from the neuron, VMAT2 serves as a marker for the presence of dopamine. In addition to VMAT2 expression, the expression of the dopamine transporter, DAT, was also observed. Altogether, these findings serve as evidence that the newly expressed TH-IR neurons, induced by short-day photoperiod exposure, are indeed synthesizing dopamine.
-
The number of intracellular SST-IR storage vesicles depended on photoperiod light-cycle duration
Panel D is consistent with the findings in Panel B and Panel C, which also demonstrate an increase in SST expression following increase day exposure.
-
The 43% increase and 96% decrease in TH-IR/SST-IR coexpression after short- and long-day exposure, in contrast to the balanced photoperiod, suggest that TH-IR and SST-IR neurons are recruited from a reserve pool of cells (23) that are switching transmitters
In response to the photoperiod exposure condition, the circuit activity changes such that the neurons of the reserve pool are switching transmitters. The researchers believe that the TH-IR and SST-IR neurons are coming from this reserve pool of cells based on their finding that short-day exposure led to an increase in the recruitment of TH-IR neurons and diminishment of SST-IR neurons, while long-day exposure had the opposite effect.
-
Double immunofluorescence revealed that different photoperiods changed the balance of dopamine and SST coexpression in neurons in the PaVN and PeVN
The experimenters performed immunostaining for both dopamine and SST expression. Panel B depicts immunofluorescence of these transmitters in the PaVN. The first of the three images depicts the results from long day exposure; under this condition, there is an abundance of red representing an increase of SST expression and very little green indicating that there is a decrease in dopamine expression. Under short day exposure (third image), the opposite is true.
-
TH expression did not differ from controls exposed to the 12L:12D photoperiod for 2 weeks
Finding that the TH-IR neuron counts are reversible upon application of opposite photoperiod treatment is further evidence that sensory stimuli can induce neuroplastic changes in the already mature brain.
-
No significant BrdU labeling was detected in the LPO, PaVN, or PeVN
BrdU labeling did not result in significant amounts of active poliferating cells; this is an initial indication that inverse SST and dopamine expression is not due to neurogenesis.
-
Week-long exposure to each of the different photoperiods failed to produce changes in numbers of TH-IR neurons in an adjacent nucleus, A13 (Fig. 1E and fig. S2B), which does not receive retinal input via the SCN
In order for the dopamine alterations to be induced by changes in light exposure duration, the dopaminergic neurons must be able to receive retinal input, as is the case with the dopaminergic neurons in the hypothalmic nuclei, innervated by the retino-hypothalmic projection. If the neurotransmitter respecificaiton is indeed due to the photoperiod treatment, dopamine production at an adjacent dopamine source, which does not receive retinal input via the SCN, should be unaffected.
-
Circadian fluctuations do not account for changes produced by different photoperiods.
Within the three photoperiods, 19L:5D, 5L:19D, and 12L:12D, the number of TH-IR neurons are similar. Because there is a consensus within each photoperiod, this is indicating that circadian fluctuations are not contributing to neurotransmitter respecificaiton.
-
FFN511 generated fluorescent signals in hypothalamic slices from brains of animals exposed to each of the three photoperiods. Fluorescence decreased upon KCl depolarization
In panel C, before KCl depolarization, there is observable fluorescent signals from FFN511, indicating dopamine uptake. Upon KCl depolarization, the fluorescence is diminished; this is indicative of dopamine release. The results of panel C are consistent with panel A and B in that during the long day light condition (19 hours light, 5 hours darkness), the fluorescence signal is the lowest, which means less dopamine being taken up.
-
Dopamine is colocalized with TH in the PaVN after exposure to each of the photoperiods. n = 5 animals for each photoperiod.
Panel B: The fact that in all three photoperiod conditions, dopamine is colocalized with TH validates the use of TH as a marker of dopamine synthesis.
-
Natural stimulation of other sensory modalities may cause changes in transmitter expression that regulate different behaviors.
The researchers found that neurotransmitters are not actually fixed upon maturation, but are, in actuality, dynamic and can be affected by sensory stimuli such as longer or shorter photoperiods. Changes in transmitter expression result in behavioral changes as well. Thus, follow up research can explore what other sensory stimuli can change transmitter expression and also examine the corresponding behaviors that are regulated by those transmitters.
-
Induction of newly dopaminergic neurons through exposure to the short-day photoperiod rescued the behavioral consequences of lesions.
Shortening the length of daylight the rats are exposed to induced the formation of new dopaminergic neurons and thereby restored the rats' previous (normal) behaviors, i.e., the rats no longer displayed anxious and depressed behaviors.
-
Pharmacological blockade or ablation of these dopaminergic neurons led to anxious and depressed behavior, phenocopying performance after exposure to the long-day photoperiod
Using drugs to prevent dopamine production resulted in anxious and depressed behaviors by the rats; these same behaviors were also observed following extended day length exposure.
-
Changes in postsynaptic dopamine receptor expression matched changes in presynaptic dopamine, whereas somatostatin receptor expression remained constant.
When more of the neurotransmitter dopamine is produced, there is also an increase in the postsynaptic dopamine receptor. Likewise, when less dopamine is produced, it follows that there is a decreased expression of dopamine receptors. However, for somatostatin, this was not the case. Regardless of whether somatostatin production is increased or decreased, the somatostatin receptor expression is unchanged.
-
- Aug 2021
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
We found that populations of interneurons in the adult rat hypothalamus switched between dopamine and somatostatin expression in response to exposure to short- and long-day photoperiods.
Altering the amount of time that a rat is exposed to light in a day leads to changes in the type of neurotransmitters being expressed by a set interneurons located in the hypothalamus. When the rat's daily light exposure is restricted to a shorter time frame, those interneurons favor dopamine expression. In contrast, longer daily periods of light exposure results in those same interneurons favoring somatostatin expression.
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
introduced plants accounted for 93.3% of dispersal events
Of all seeds found on bird poops, 93% are of introduced plant species
-
- Feb 2020
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Hence, predator behaviour may aim to maximize foraging success based on both prey behaviour and the physiological processes that can influence behaviour of prey (i.e. metabolic rates).
The original hypothesis that shark behavior would be solely tied to their own temperature (most active when warm and resting when cool, or some other binary relationship) is revised in light of the more nuanced pattern that the researchers observed in the data.
Here, the authors present a new hypothesis that also includes the temperature and behavior of prey, pointing out that the sharks may be most active when the temperature gap between predator and prey is the largest due to their differences in thermal inertia. When the shark is cooling, the fish upon which it preys will have cooled down even more, reducing their ability to escape from the still relatively warm shark.
-
- Dec 2018
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
larger fish have greater thermal inertia and increased cardiac capacity
Thermal inertia is the ability of a body or object to maintain its temperature when ambient temperature changes. Larger objects have higher thermal inertia, so larger fish lose heat more slowly than smaller fish. Larger fish also have larger hearts, which can pump more blood.
-
The largest size-based differences in energy intake were also observed in October (Fig. 6 and table S3), indicating that thermal niche expansion in this endothermic species results in high energetic reward.
The increased temperature range allowed the tuna to forage and obtain energy more efficiently.
-
Lower energy intake was observed during late summer (August and September), when bluefin tuna are moving up through the Southern California Bight (28° to 32°N).
Lower energy intake during migrations.
-
- Dec 2017
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Table 1
mtDNA CO1 is a gene found within the mitochondria, it is used to measure the genetic difference between organisms. A higher mean indicates a larger difference between two organisms, which is indicative of being a different species. (JP)
-
Fig. 2
In general, this graph illustrates that as genetic distance between species increases (this is measured by Nei's D) then mtDNA divergence increases as well. Overall, compatibility between two different organisms will be less if they have high mtDNA divergence and a high Nei's D value. (JP)
-
All the shrimps we studied are shallow water, fully marine forms with planktonic larvae.
Main subjects studied. Planktonic larva is significant in this study because larva shrimp would migrate to different regions of the Isthmus of Panama which may be a significant contributor to speciation events ~J.D.A. (+ JP)
-
Even the least divergent pairs show substantial reproductive isolation
Species so closely related showed two differ clutches. Isolation could've been geographical, though nothing that could completely cut them off from each other since they are similar. If anything, this could infer that they could've been selective in mating, or aggressive in behavior to even mate, thus preventing creation of offspring between them. ~J.D.A
-
The null hypothesis, that isolation was simultaneous but rates of divergence are highly variable, is incompatible with the observed pattern because metabolic enzymes, mtDNA, and mate recognition share no mechanistic basis that would cause their divergence rates to be automatically associated.
Basically, the null is rejected because it contradicts the observed data. The null states that isolation occurred around at the same time, but the observed data shows divergence indicators such as metabolic enzymes, mtDNA, and mate recognition, all of which are not associated at a single mechanistic basis required for concurrent divergence. ~S.Z.
-
However, they do show some distributional differences that could affect sensitivity to changing conditions associated with gradual rise of the isthmus.
The physical location of the shrimp could effect the divergence associated with the gradual rise of isthmus. ~S.Z
-
Pacific members of the most divergent pairs are found deeper in the intertidal or are rare in habitats with heavy sedimentation (25) (Fig. 2). Thus, larval avoidance (26) of shoaling waters over the rising isthmus (6, 7) may have accelerated genetic isolation of these pairs.
The shrimp located closer to the sea floor had a slimmer chance of being pushed over the isthmus; therefore had a higher chance of isolation and divergence. ~S.Z.
-
Our data can also be used to estimate rates of divergence in reproductive compatibility. Even the least divergent pairs show substantial reproductive isolation
The less compatible they are the more they have diverged. ~S.Z.
-
Geographic isolation is thought to permit divergence and speciation by disruption of gene flow
The physical barrier created by the Isthmus of Panama prevented the exchange of genes; therefore, allowing the organism to develop differently on wither side of the barrier or diverge. (SZ)
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
a phosphorylation-mimicking Thr205→Glu205 (T205E) tau variant coprecipitated significantly less with PSD-95 as compared with nonmutant and T205A (A, Ala) tau (Fig. 4C and fig. S21)
Phosphorylation at T205 inhibits complex formation.
-
T205 phosphorylation of tau is part of an Aβ toxicity–inhibiting response.
Phosphorylation at T205 on tau limits Amyloid beta toxicity.
-
p38γ regulated PSD-95/tau/Fyn complexes, likely at the level of PSD-95/tau interaction
From Fig. 3 the authors conclude that p38y reduces PSD-95/tau/Fyn complex formation by affecting PSD-95/Fyn interactions.
-
PTZ transiently increased PSD-95/tau/Fyn complex formation in p38γ+/+ animals; this effect was even more noticeable in p38γ−/− mice
p38y was shown to inhibit the formation of complexes, but the addition of PTZ lowers the protective function of p38y.
-
PSD-95/tau/Fyn interaction was reduced in transgenic mice with neuronal expression of p38γCA
The interactions that are required to form the complexes are reduced in mice with an active form of p38y, demonstrating that p38y may prevent complex formation.
-
PSD-95 copurified more tau and Fyn from p38γ−/− versus p38γ+/+ brains, and even more from APP23.p38γ−/− compared with APP23.p38γ+/+ and p38γ−/− brains
An immunoprecipitation for PSD-95 was ran. The proteins that were associated with PSD-95 complexes also precipitated due being in a complex with PSD-95. The results show that tau and Fyn were contributing more to the PSD-95 complexes when p38y was not present.
-
PSD-95/tau/Fyn interaction was enhanced in Alz17.p38γ−/− animals versus Alz17.p38γ+/+ mice
Results show that more PSD-95/tau/Fyn complexes were in the brains of p38𝛾-/- vs. p38𝛾+/+. This shows that PSD-95/tau/Fyn complexes are associated Amyloid-beta induced excitotoxicity
-
when compared to tau−/−.p38γ+/+mice, tau−/−.p38γ−/− animals showed similar protection from PTZ-induced seizures
p38y only protects agianst PTZ-induce siezures only when tau is present. A difference between p38y being present and p38 being absent is only seen in mice that have tau.
-
These data also showed that, compared with APP23 mice, APP23.p38γ−/− animals had aggravated memory deficits that persisted with aging
APP23.p38y+/+ mice survived longer and had performed better in water maze than APP23.p38y-/- mice. Also shown in the results is that APP23.p38y+/+.tau-/- vs. APP23.p38y-/-tau-/- mice, are statistically the same, suggesting that the protective effect of p38 comes from phosphorylating tau.
-
The exacerbating effects of p38γ loss on reduced survival, memory deficits, and neuronal network dysfunction of APP23 mice were virtually abolished in APP23.p38γ−/−.tau−/− mice
The APP23 deficits improved when tau was not present in mice.
-
p38γ−/− mice showed no deficits and had normal motor function
The lack of p38y kinase did not negatively affect the movement and motor function of the mice.
-
Aβ pathology was comparable in the brains of APP23.p38γ−/− and APP23.p38γ+/+ mice (fig. S6), but p38γ deletion aggravated premature mortality and memory deficits of APP23 mice
APP23 mice that had p38y and did not have p38y displayed similar traits, but the deficits in mice that did not possess p38y kinase were worse.
-
Surprisingly, only p38γ depletion (p38γ−/−), but not systemic p38β, p38δ, or neuronal p38α (p38αΔneu) knockout, changed PTZ-induced seizures
The only knockout mouse that displayed a change associated with PTZ-seizures was p38y. Because p38y was the only one that influenced the results, it is the focus of all the experiments.
-
Finally, we found that tau-dependent Aβ toxicity was modulated by site-specific tau phosphorylation, which inhibited postsynaptic PSD-95/tau/Fyn complexes, revealing an Aβ toxicity–limiting role of p38γ in AD that is distinct and opposite to the effects of p38α and p38β (11, 13, 14).
The authors state, contrary to popular belief, that tau can play a protective role in limiting amyloid beta toxicity by interacting with p38γ. By phosphorylating specific sites tau can increase neuron survival and improve memory loss.
-
PTZ-induced seizures are reduced in tau−/− mice (8, 9). Adeno-associated virus (AAV)–mediated expression of WT and T205A neurons, but not T205E tau or green fluorescent protein (GFP), in the forebrains of tau−/− mice enhanced PTZ-induced seizures (Fig. 4D and fig. S25).
The data shows that the tau-/-.AAV tauWT and tau-/-.AAV tauT205A were the most susceptible to seizures and had the most severe seizures out of the four genotypes.
-
Hence, phosphorylation of tau at T205 should similarly mitigate neurotoxicity. Aβ caused cell death in WT and T205A neurons but significantly less in T205E tau-expressing neurons (fig. S23). Similarly, neurons expressing p38γ and, more so, p38γCA were significantly more resistant to Aβ-induced cell death than controls (fig. S24).
The results from previous experiments showed that neurons survived at higher rates when they had T205E and p38γ.
-
Pan-p38 inhibition stopped p38γ/p38γCA-induced disruption of PSD-95/tau/Fyn complexes
If p38y is completely inhibited, the complexes are stable.
-
Hence, p38γ regulated PSD-95/tau/Fyn complexes via phosphorylating tau at T205.
The results of this experiment showed that p38γ helped to disrupt the PSD-95/tau/Fyn complexes through phosphorylation of T205.
-
Increasing p38γ levels compromised PSD-95/tau/Fyn interaction in cells, and expression of a constitutively active p38γ variant (p38γCA) completely abolished this interaction
p38y was shown to prevent the interactions required to form the complexes associated.
-
Similarly, pT205 was markedly reduced in APP23.p38γ−/− animals compared with APP23.p38γ+/+ mice (Fig. 4B)
The results of the previous experiment showed that APP23p38𝛾-/- mice had decreased T205 phosphorylation compared to the APP23p38𝛾+/+, which had T205 phosphorylation.
-
no PSD-95/tau/Fyn complexes were isolated from tau−/− and tau−/−.p38γ−/− brains
Demonstrates that the complexes will not form if unless tau is present.
-
In summary, the levels of active p38γ kinase and tau phosphorylation at T205 determined susceptibility to excitotoxicity and Aβ toxicity.
-
the effects of p38γ on excitotoxicity and Aβ toxicity were tau-dependent.
The protective qualities of p38y are dependent on tau being present. If tau is not present, amyloid-beta toxicity effects the cells the same, even if p38y is present.
-
increasing tau levels in p38γ−/− mice [brought about by crossing with nonmutant tau-expressing Alz17 mice (23)] significantly enhanced PTZ-induced seizures in Alz17.p38γ−/− mice
Mice that had higher levels of tau were more susceptible to seizures.
-
In summary, p38γ depletion exacerbated excitotoxicity, neuronal circuit synchronicity, mortality, and memory deficits in APP23 mice, without changes in Aβ pathology.
Overall, every deficit associated with APP23 was made worse when p38y was not present.
-
Electroencephalography showed enhanced spontaneous epileptiform activity and interictal hypersynchronous discharges in APP23.p38γ−/− compared with APP23.p38γ+/+ mice
From the results, the researchers can infer that the presence of p38𝛾 kinase has a protective ability that lessens the amount of seizure trains that occur due to Aβ density bodies
-
Compared with APP23.p38γ+/+ mice, APP23.p38γ−/− animals had increased sensitivity to PTZ-induced seizures
From the results conducted in the experiment, specifically the Fig. 1 G-J, mice that did not possess p38y were more sensitive to seizures
-
only p38γ localized to postsynapses and limited excitotoxicity.
The only knockout mouse that was shown to cause a change in PTZ-induced seizures was p38𝛾. p38𝛾 was also the only kinase that was shown to localize in postsynapses between neurons.
-
- Nov 2017
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
mimicking site-specific tau phosphorylation alleviated Aβ-induced neuronal death and offered protection from excitotoxicity.
The site that is phosphorylated by p38y was found to be important for reducing effects of AD. Demonstrates that the function of p38y is important, and the mere presence of p38y in the cell is not protective, it has to be functional.
-
depletion of p38γ exacerbated neuronal circuit aberrations, cognitive deficits, and premature lethality in a mouse model of AD, whereas increasing the activity of p38γ abolished these deficits
The research found that the presence of p38y reduced the effects of AD in the mouse model.
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
first, the sex-determining proteins studied in the present work evolve at constant rates, as suggested by global molecular clock tests (Table 1).
From Table 1, the following sex-determining proteins display InL, InL(clock), and the p-value. These factors display the final calculations. From what the author first concluded, the InL(clock) values show that there is in fact a constant rate with which the proteins evolve. It is tested by the likelihood ratio tests based off the models of evolution defined. -Melanie
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
The high levels of genetic differentiation detected within C. jimenezii raise questions whether these two populations can be treated as different varieties/subspecies within this taxon or if indeed they may represent two different species.
In this study, the researchers found some questions as to whether the two species of C. jimenezii could be grouped with the same taxa.
Upon meeting with the author, it was stated that the molecular tools used, found a large amount of differentiation. This was not what the authors hoped and in turn was concluded that they were to remain in separate taxa.
RA
-
Therefore we recommend not translocating material between these two populations for genetic conservation or ecological restoration programs until the taxonomy of this species within Coccothrinax is further studied.
Genetic conservation of this population is important due to the few individuals left in Haiti and the Dominican Republic.
Upon meeting with the author, the difficulty of finding the purebred species was discussed as were the methods.
RA
-
The taxonomic uncertainties between the two populations of C. jimenezii have important implications for reintroduction programs. These two sites of C. jimenezii represent two clear management units for conservation, and the population genetic data suggest that we cannot rule out that they are two distinct taxa.
The authors concluded based off of the molecular data, that the two species of C. jimenezii could not be identified as two different taxa.
RA
-
We have not been able to find data regarding the environmental history in these two populations since the 15th century. However, there is agreement among conservation biologists that since the arrival of the Europeans to this island there has been habitat fragmentation and deforestation linked to rapid expansion of urban and rural activities (Sambrook et al., 1999; Alscher, 2011; Foxx, 2012). Palms have long-life cycles; therefore, the detrimental consequences of genetic drift on genetic diversity can take a long period of time to manifest because of their long generation time and the presence of overlapping cohorts (Duminil et al., 2009).
Since the extinction of C. jimenezii is of primary concern, the authors grab resources from other works to help solidify this concept. It is clear that the conservation of this species is vital to this study.
RA
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
The answers to fundamental questions about the origins of animal life and the evolution of their diverse phenotypes may be held in the genomes of distinct invertebrate phyla.
The conclusion explains why they investigated what standards an invertebrate must reach to be tested for a successful genome sequencing. The researchers also add that geneticists could choose another option than searching an organism that meets their criteria. This option is sequencing organisms and modeling them for another organism. This would allow the geneticist to understand the other organism by having an idea of how the genome functions.
The researchers also state a challenge faced by the science community is understanding the data they collect from the genome sequence, apart from also gathering the sequences. They state the research they do will help advance knowledge about invertebrate genomes by providing the necessary tools to investigate the sequences. (NAJ)
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Likewise, there is no evidence for differences among the pairs in historical effective population sizes or generation times that can be related to divergence (20).
The generation types (ex. F1, F2, etc.) and population size were taken into account for each shrimp pair. These factors were found to not support the phenomenon of divergence among shrimp pairs because no differences were found. ~J.D.A.
-
Our data can also be used to estimate rates of divergence in reproductive compatibility.
The less compatible they are the more they have diverged. ~S.Z.
-
Pacific members of the most divergent pairs are found deeper in the intertidal or are rare in habitats with heavy sedimentation (25) (Fig. 2). Thus, larval avoidance (26) of shoaling waters over the rising isthmus (6, 7) may have accelerated genetic isolation of these pairs.
The shrimp located closer to the sea floor had a slimmer chance of being pushed over the isthmus; therefore had a higher chance of isolation and divergence. ~S.Z.
-
However, they do show some distributional differences that could affect sensitivity to changing conditions associated with gradual rise of the isthmus.
The physical location of the shrimp could effect the divergence associated with the gradual rise of isthmus. ~S.Z
-
The null hypothesis, that isolation was simultaneous but rates of divergence are highly variable, is incompatible with the observed pattern because metabolic enzymes, mtDNA, and mate recognition share no mechanistic basis that would cause their divergence rates to be automatically associated.
Basically, the null is rejected because it contradicts the observed data. The null states that isolation occurred around at the same time, but the observed data shows divergence indicators such as metabolic enzymes, mtDNA, and mate recognition, all of which are not associated at a single mechanistic basis required for concurrent divergence. ~S.Z.
-
Geographic isolation is thought to permit divergence and speciation by disruption of gene flow
The physical barrier created by the Isthmus of Panama prevented the exchange of genes; therefore, allowing the organism to develop differently on wither side of the barrier or diverge. (SZ)
-
All the shrimps we studied are shallow water, fully marine forms with planktonic larvae.
Main subjects studied. Planktonic larva is significant in this study because larva shrimp would migrate to different regions of the Isthmus of Panama which may be a significant contributor to speciation events ~J.D.A. (+ JP)
-
Fig. 2
In general, this graph illustrates that as genetic distance between species increases (this is measured by Nei's D) then mtDNA divergence increases as well. Overall, compatibility between two different organisms will be less if they have high mtDNA divergence and a high Nei's D value. (JP)
-
Table 1
mtDNA CO1 is a gene found within the mitochondria, it is used to measure the genetic difference between organisms. A higher mean indicates a larger difference between two organisms, which is indicative of being a different species. (JP)
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Energy intake and thermal excess were positively correlated with body size as measured by the curved fork length (CFL) of tagged tunas
A big tuna (large body size) requires more energy which means it needs to feed from a higher amounts of prey or big preys. Consequently, the heat production is higher provoking a thermal excess. YS & WT
-
Lower energy intake was observed during late summer (August and September), when bluefin tuna are moving up through the Southern California Bight (28° to 32°N).
Lower energy intake during migrations - M.A.S
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Management of nutrient effects on both of these pathways would positively affect riverine health.
The purpose of these experiments were to test the effects of nutrients on terrestrial carbon loss that ultimately leads to a change in ecosystems.
Learning the effects and ideal ratios of nitrogen to phosphorus for ecosystems will lead to better policies to protect them.
-
Litter quantity in the streambed was predicted to be 2.8 times and 7.7 times higher in reference versus nutrient-enriched streams after 6 and 12 months,
In the experiment, it was found that the addition of nutrients encouraged terrestrial organic carbon loss.
This was tested by observing the litterbags of the experimental streams and comparing the data to the litterbags of the control stream.
Since a large amount of mass was lost in the stream with nutrient additions, this gives some evidence that too many nutrients off-balances organic carbon levels.
-
Reach-scale outputs of C increased as fine POC export, as well as respiration (15).
Fine POC export represents the movement of broken down carbon along the stream. Finer particles move faster and further down a stream as biological factors such as microbes and fungi decomposing the terrestrial organic carbon.
-
They may limit terrestrial C loss as CO2 and maintain downstream C export, but contribute to depletion of local C resources (22, 23).
Detrivores have a different method of carbon depletion from streams. finer particulate organic carbon travels faster and further away from an area, deleting the area of carbon sources.
Invertebrates may leave the system if there are no food sources and alter the food chain.
-
However, roughly similar-sized effects of N and P on loss rates are strong evidence of co-limitation (Fig. 2 and table S3).
Both nitrogen and phosphorus are contributing factors to changes in terrestrial carbon loss.
Within the ecosystem, different organisms require different ratios of nutrients to react and convert terrestrial carbon to carbon dioxide.
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Another study in which mouse NC cultures were treated with Edn3, Edn1, or Kitl showed an increase in the number of melanocyte progenitors; however, Kitl alone was not sufficient to induce the differentiation of melanocyte progenitors into mature melanocytes. Mature melanocytes were however observed, when treatment with Kitl was followed by Edn3 or Edn1 (Reid et al., 1996). As previously noted, although in the absence of Edn3, Kit-positive and DOPA-positive cells arose in mouse NC cultures, Ednrb signaling was required for the generation of fully pigmented melanocytes (Ono et al., 1998). These findings hint to a specific requirement for Ednrb signaling, independent of Kit signaling, in melanocyte differentiation. This requirement for Ednrb in the final phase of melanocyte differentiation may occur cell-autonomously, as suggested by the inability of Ednrb null cells to generate pigment even in the presence of Kitl (Hou et al., 2004). Together these findings point at a cooperative interaction between Kit and Ednrb signaling in melanocyte development, with Ednrb signaling being specifically required in the final differentiation step
This paragraph discusses how Ednrb is needed in order to further a melanocyte into melanoma, even if Kitl (another signaling pathway) is present. Therefore, this is the direct link to melanoma.
(NB)
-
- Oct 2017
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Table 2
By quantifying behavioral tolerance and intolerance of male-female transisthmian pairs, the researchers are able to compare interactions between closely related and distantly related species of snapping shrimp.
For example, while keeping figure 1 and table 2 in mind, more closely related species have higher compatibility compared to more distantly related species. Although this is not an indicator of having viable offspring, this shows that closely related species may share similar behaviors or may have similar niches. (JP)
-
Fig. 1 Single most parsimonious phylogenetic tree constructed on the basis of mtDNA sequences with PAUP (18). Transitions were given one-quarter the weight of transversions (based on the fourfold greater abundance of transitions than transversions in our data), and trees were rooted by the P7-P7'-C7 clade. Taxon codes are as in Table 1.
Figure 1 is a visual representation of the relationship between differing species of snapping shrimps. This diagram was made using the mitochondria DNA sequences of the organisms and the PAUP program which calculates the level of relatedness between the sibling species of snapping shrimp.
Comparing Table 1 with Figure 1, it is found that species more closely related, such as P2 and C2, had a lower mtDNA mean value (6.6). Meanwhile, species that were more distantly related, such as P7' and C7, had a higher mtDNA mean value (19.7). (JP)
-
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
our findings suggest that the overexploitation of spawning aggregations can fundamentally alter the natural predator-prey equilibrium, limiting foraging options for reef sharks within aggregation sites.
The inverted biomass pyramid is a good thing, but the fish spawning aggregations play an important role in whether or not this stays a good thing.
- D.N.B.
-
These observations confirmed that hundreds of sharks actively feed on a large variety of prey (at least 14 fish species; Figures 4 and S3). In particular, sharks feed aggressively on the large number of groupers present during spawning aggregations in June and July [13]. Shark abundance and residency times both increase when camouflage groupers (Epinephelus polyphekadion) arrive from the surrounding reef area to spawn
there is an active correlation between the populations of prey and predators, when the camouflage groupers aggregate in order to spawn. This increase in prey is what attracts the sharks. MSARS , WT & YS
-
Overall, sharks showed different degree of residency (mean ± SEM = 42.21% ± 7.75% of days present in the pass; range = 2.1%–95.9%; Table S3), with three transient (<20% residency), six semi-resident (20%–70% residency), and four highly resident (>70% residency) sharks (Figure S2).
The study showed that overall, there was a higher number of sharks observed that spent most of their time in the pass than there were that spent less of their time in the pass. YS & WT
-
- Aug 2017
-
www.scienceintheclassroom.org www.scienceintheclassroom.org
-
Western assay of induced SX4 cells showed the presence of Venus only in the membrane fraction and not in the cytoplasmic fraction, suggesting efficient membrane localization of Tsr-Venus.
The e coli strain engineered by the authors is behaving as they predicted.
-