This early research provides evidence for the importance of chemical signaling pathways as the major form of cell-to-cell communication and play a role in the body throughout an animal's lifetime.

Wallingford and colleagues found evidence for the important role that the protein known as Dishevelled plays in cell fate (how cells know what type of cell to become); how cells know where to go (head or tail), and how cells interact with each other in the animal body. Dishevelled has been found to play this same role across many animal species, which indicates its importance.

Basins located in the eastern Rocky Mountains of the United States were the primary area of interest. Maps showing the location of several of these basins can be seen at the following sites: Map of Williston Basin https://serc..edu/details/images/35362.html

Map of San Juan Basin https://www.mapsofthepast.com/san-juan-basin-usgs-1959-2941-x-23.html

Map of Hanna Basin https://www.researchgate.net/figure/Map-showing-the-Hanna-Laramie-and-Shirley-Basins-Wyoming-including-major-structural_fig1_284185996

Map of the Denver Basin https://www.researchgate.net/figure/Map-of-the-Denver-Basin-within-Colorado-Wyoming-and-Nebraska-with-structure-contours-on_fig1_265508368

Earlier research showed that the Corral Bluffs area has a relatively continuous K–Pg boundary stratigraphic sequence. It is the most extensive surface exposure in the Denver Basin and allows for the opportunity to interpret fossil collections in the context of K–Pg boundary extinction and recovery.

In their study, MacLeod et al. reported the values of the oxygen-18 isotope (δ18O) in phosphate compounds isolated from sand-sized (~0.1 to 2 mm) remains of fish teeth, scales, and bone from El Kef, Tunisia, that indicate a warming trend of ~5°C beginning at the K-Pg boundary and lasting for ~100,000 years. This supported similar findings by the author of this research article.

Tobin et al. analyzed fossil bivalve shells for carbonate-clumped isotopes. Their findings confirmed a decrease in summer temperatures over the last k.y. of the Cretaceous. This cooling trend accounts for declines in vertebrate and invertebrate biodiversity, making the destabilized ecosystem more susceptible to the asteroid impact.

In communities of present-day mammals, ecological richness is primarily driven by vegetation type. The fossil record shows that some plant groups, such as gymnosperms (pines, spruce, and firs), decreased in diversity as a result of the K-Pg extinction. Angiosperms (flowering plants), on the other hand, underwent a rapid increase in diversity. When becoming dominant, angiosperms allowed for the evolution of a diversity of mammals and other animals.

Several different dating techniques have determined that the K–Pg boundary layer in the Denver Basin overlaps with the age of the K–Pg boundary layer in the Hell Creek Formation in Montana. The age of both these areas is the same as that of tektites from Chicxulub where the asteroid impact occurred. This provides strong support for the contemporaneous deposition of ash and debris across western North America directly after the Chicxulub impact.

The authors spent many years looking for mammal fossils in different locations in the western U.S.

It has been shown that there is a strong relationship between Earth’s geochemical cycles and the biosphere. An example would be that the many volcanic eruptions occurring in the Deccan Traps likely released greenhouse gases that triggered post-KPgE warming periods. These periods resulted in a greater diversity of plant species, which in turn supported larger bodied mammals.

Lamichhaney and colleagues (2015) searched genomes of closely related species that had different beak sizes and identified ALX1, a homeobox gene that controls development in the face and neck, and correlates well with differences in beak shape.

Lamichhaney and colleagues (2016) analyzed finches whose beak sizes changed during a drought and identified HMGA2, a nearby gene locus also related to beak size.

Grant et al. did the experiment described here with a population of G. difficilis on Isla Genovesa.

They played tape-recorded songs from several G. difficilis populations (Isla Genovesa, Isla Wolf, and Isla Darwin) and demonstrated that the finches responded strongly to their own population's song, weakly to the Isla Darwin population's song, and not at all to the Isla Wolf population's song.

In 2004-05, a severe drought caused competition between two species of finch on the island of Daphne Major. The medium ground finch (G. fortis) and large ground finch were in competition for decreased food sources. Because medium ground finches with large beaks were at a disadvantage, the size of beaks for these finches decreased as a result of this selection pressure.

This natural experiment was studied by Lamichhaney and colleagues (2016) and by Grant and colleagues (2014).

Bolsted and colleagues describe how they changed the allometric relationship of wing size to body size in fruit flies, Drosophila melanogaster, through artificial selection.

This shows that selection can change allometric relationships and supports the authors' suggestion that natural selection is the cause of the changes in allometric relationship between bill size and body size in the Big Bird population.

By measuring bill size and recording bird mortality on Daphne Major during a drought that occurred in 2004-05, scientists were able to establish the characteristics of bills that were adaptive during this period of decreased food supply.

The plant species mentioned is a food supply for the Big Bird lineage, so this data on bill morphology is relevant to understanding this hybrid population.

In "40 Years of Evolution" (reference 12), Grant and Grant devote an entire chapter to the analysis of this possible new hybrid species that supports these conclusions about bill and body size, as well as song. 

Their analysis includes extensive pedigrees and data on beak depth and width, heterozygosity, and song analysis.

The current paper explores the beak morphology and genetic data more closely to contribute to the understanding of the hybrid lineage success and reproductive isolation.

In 2010, Grant and Grant analyzed genetic data to search for the effect of breeding with immigrant birds (reference 16). They used genetic studies to quantify the effect of genes from the same species (from populations on other islands) compared to those of different species.

Rosemary and Peter Grant developed this idea based on observations of mating pairs, as well as experiments. In some experiments, they played recorded birdsongs from either the same or a different species and recorded the birds' responses. Other experiments involved presenting birds with a stuffed specimen of either the same or a different species and recording their responses.

Rosemary and Peter Grant have led the study of the bird species of the Galapagos Islands since the 1970s. Individual birds on the island have been banded and described, so migrants such as the one described can be identified when they arrive.

Schumer and colleagues present three criteria: 1) demonstration of a mechanism of reproductive isolation, 2) evidence of hybridization (preferably genetic and based on whole genome evidence), and 3) hybridization-derived isolation (establishing that the hybridization led to the reproductive isolation and not some other factor).

Researchers at Rutgers created a scaffold, or 3D pattern of cells, by assembling Type-1 collagen. collagen is the most abundant tissue in the ECM. Type-1 collagen specifically is the most abundant collagen used to strengthen and support tissues in the body. The researchers chemically modified the collagen such that it can assemble into 3D structures in the presence of ulraviolet light (light with a shorter wavelength than visible light but linger than x-rays and gamma rays). This allowed researchers to control 3D assembly of collagen through light. Similarly, collagen structures can be assembled by controlling pH, temperature and collagen concentration using chemically modified collagen.

Jordan S. Miller notes that 3D printing facilitated creation of tissue constructs with live cells. However, he argues that in order to engineer functional artificial organs, the construct should contain 1–10 billion functioning cells. Furthermore, these constructs should control the spatial arrangement of cells and contain complex vascular networks and functional nerves.

Previous work done by S. J. A. Koh et al. tested how to achieve linear actuation with planar actuators using this method, allowing these authors to replicate these trials using their single and two-unit actuators.

Experiments have been performed to test the ability of liquid dielectrics versus solid dielectrics. Liquid dielectrics are able to repair themselves after dielectric failure or damage. Using liquid dielectrics allow for longer lasting actuators, resistant to breakdown, puncture and other damage. However, they do not generate too much movement (<5% strain).

Fault tolerant dielectrics are able to recover from breakdown. There are multiple ways to accomplish this recovery. The device in the paper uses a liquid dielectric. When the liquid dielectric breaks down, only a portion of the overall dielectric is effected. Then when the breakdown event stops, the electricity stops, the remaining dielectric liquid fills in the damaged areas, effectively healing the actuator.

When voltage is applied across dielectric materials, they do not conduct electricity but rather get polarized, by accumulating positive and negative charges within the material. Dielectric breakdown happens when the voltage is so high that the dielectric begins conducting electricity. A breakdown event briefly makes the dielectric material conductive, allowing for high amounts of current to flow through, typically causing permanent damage to the material

Experiments have been conducted to optimize the abilities of dielectric elastomers. It has been discovered that pre-straining the elastomers, like stretching a balloon, allows the elastomers to achieve a higher strain at a faster rate. Pre-straining is the process of applying a force to a material before actual use. When you stretch a balloon before blowing air into it, you are "pre-straining" the balloon. This allows the material to "get use to" the forces it will experience. Also, computational models helped determine the best ways to pre-strain elastomers such that a specific 3D shape is achieved.

Fluid actuators, which converts fluid pressure into movement, were previously used in soft robots. This would make actuators bulky, slow and less efficient because of tanks and channel systems needed to generate the pressure.

Traditional robots require rigid structures. This has caused design considerations to work around the machines rather than the problem being solved. Soft robotics seeks to eliminate the rigid structure problem.

Most importantly, for biomedical problems, soft robots provide flexibility and adaptability for accomplishing tasks in a way similar to humans. They also provide a platform for safer interaction with humans.

Capacitive self-sensing is an sophisticated approach to drive actuators in closed loop because it does not require any additional or external sensing elements. A simple proportional integral (PI) controller was used in this work to successfully demonstrate the application of capacitive self-sensing for closed-loop operations, and a tunable grating actuator was used to test the actuation scheme.

Previous work using an electromechanical oscillator consisting of three artificial muscles was used to measure capacitance by applying low-amplitude AC voltage. Dielectric Elastomer Actuators (DEAs) were used as flexible capacitors. The oscillator supported a set of rails on which a ball was placed. Upon actuation, the rails tilted, rolling the ball.

Kook and colleagues studied the plasma levonorgestrel concentrations following the oral administration of Levora tablets in females between the ages of 19 and 44. The mean concentration observed was 14.1 +/- 7.9 ng/mL.

This data serves as a comparison for the serum concentrations that was observed in the pigs.

While the drug concentration in the serum is in the range of nanograms/ml in humans, it is in the picograms/ml range in pigs.

Dr. Salessiotis experimentally measured the diameter of a fully functioning pylorus. It was concluded that a diameter of 1.9 cm was never exceeded.

When unfolded, the smart pill spans larger than this reported size.

The authors have previously shown that this smart pill can release drug for infectious diseases for a period of 1-2 weeks. Here, the authors extend this time to 4 weeks for the oral contraceptive application.

The boundary is a thin band of rock with a high concentration of platinum (heavy) metals. L. Alvarez et al. hypothesized that this layer resulted from an asteroid impact. Evidence is based on the concentration of these metals in Earth’s crust as compared to their cosmic abundance. The asteroid impact resulted in both the asteroid and rock from Earth’s crust being pulverized and sent as dust into the atmosphere. This dust was distributed worldwide. By sampling deep-sea sediments, Alvarez et al. found that the boundary rock contained higher concentrations of platinum metals than the surrounding Cretaceous and Tertiary limestones, supporting the asteroid impact hypothesis.

The passage times of ingested food/drugs through the digestive system is slower in pigs compared to humans. Therefore, before applied to humans, the design of the smart pill should be modified. The smart pill's residence time in the stomach should be lengthened and the period of drug release should be shortened. This design change will ensure that the smart pill releases all its drug content while in the digestive system.

Kirtane and colleagues developed a once-weekly oral drug delivery system for HIV medication. The smart pill was unique in its drug-polymer matrices, which allowed week-long drug delivery at the desired concentration.

This matrix-based system was applied to the smart pill developed in this work.

The use of microneedles has been proposed as an alternative contraceptive, which works through applying a pain-free patch that administers hormones at regulated times.

Wu and colleagues reviewed past strategies of developing injectable hormonal contraceptives. Their analysis describes the use of injections to form drug deposits as a long-term contraceptive option.

Hooper studied contraceptive pill users by analyzing the results of an online questionnaire. The attitudes, awareness, compliance, and preferences of users were assessed.

Analysis revealed non-compliance (failing to take a pill altogether or taking a pill at the wrong time) by many users, including missed doses or doses taken at an incorrect time.

Researchers at the Department of Genetics and Pathology in Rudbeck Laboratory studied three vascular endothelial growth-factor receptors (VEGF) responsible for regulating the cardiovascular system. They showed the importance of controlling angiogenetic-growth-factors (such as proangiogenic) that are responsible for the formation of blood vessels. Fibronectin is not mentioned by name but other glycoproteins are emphasized for their importance as receptors for VEGF.

Dvir and colleagues used stem cells to print patches of heart tissue and showed that they had functioned properly and contained blood vessels (a sign of healthy tissue). Once they had a process to create the tissue they were able to print a full scale, anatomically correct, functioning heart.

Thomas Hinton and colleagues at Carnegie Melon University developed a hydrogel bath in which a syringe injects another gel that solidifies with a precision up to 100 micro-meters. The gel bath was then removed by raising the system temperature from 22°C (71.6°F) to 37°C (98.6°F) while the deposited material simultaneously remained solidified.

In this study, it was discovered that balsam fir, the island's original dominant tree species, was not able to recruit, as it was a favorite food for deer. White spruce, and several companion species, have replaced the fir, as deer do not find them palatable.

A number of different factors led to the success of the brown tree snake in Guam: barrier-free dispersal, few safe areas for avian prey, lifestyle of the predator (nocturnal and arboreal), and the ability of the predator to find prey under varying conditions.

A metastudy of 45 replicated and 35 unreplicated field experiments found that introduced predators had double the negative effect than of native predators on their vertebrate prey:

Read more: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1950296/

Herbivores produce large amounts of methane, a potent greenhouse gas, as a byproduct of their diet. By losing so many of these organisms during the Pleistocene and early Holocene, the methane concentration in the atmosphere would have dropped rapidly, helping to cause the global cooling of the Younger-Dryas.

By allowing the expansion of the predator population (spiny lobster), the size of the prey population (sea urchins) was held in check and individual urchins suffered from disease less often.

The kelp forests of Alaska and the Aleutian Islands were monitored for up to 15 years to evaluate the impacts of top-down controls by sea otters on the community structure of the region.

In this study, it was noted that ungulates above 150 kg were regularly limited by food availability instead of predation, due to their large body sizes.

Conversely, small ungulates (<150 kg) were regular prey of the several large carnivores on the Serengeti, and their populations, and the trophic levels below them, were controlled by the apex predators.

Loss of predators in these systems caused much greater impacts on the smaller herbivores than the larger ones.

A metastudy of 41 papers and 60 independent tests found that terrestrial trophic cascades occurred more frequently than previously thought across systems and were on par with those in aquatic environments. While the strength of the cascade response varied across systems based on several factors (type of carnivore, plant antiherbivore defenses, type of damage measured, etc.), trophic cascades were common, although not universal.

To see the effects of one such natural experiment, read "Ecological meltdown in predator-free forest fragments," from Terborgh et al. in Science.

Also can be found in the "Related Content" sidebar.

To learn more about the interesting work on the complex impacts of trophic cascades, see research in Science (Ngai & Srivastava, 2006; Chapin III et al., 1997; Myers et al., 2007).

PDF downloads of these papers can be found under "Related Content."

Humans have a number of different impacts on the biosphere, but loss of apex predators is thought to be one of the widest ranging issues of the planet.

An overview of the threats to the planet's largest 31 carnivores and implications can be found here.

The study (Ripple et al.) can also be found in the "Related Content" sidebar.

J. D. W. Madden et al. previously reported strain percentages of 20%, which is comparable to the experimental strain of 37% achieved in this paper.

A Weibull distribution works similar to a normal distribution or a grading "bell-curve". In previous experiments, it was shown that the likeliness of a dielectric breakdown is based on a specific Weibull distribution.

Iglay, Cao, Mavros, Joshi, Yu, and Tunceli reviewed twenty-two observational studies regarding how often chronic disease patients took their medication. Patients prescribed once-weekly and once-daily doses were compared.

The analysis showed that patients needing to take doses once a week were more likely to take their medication than patients needing to take doses once a day.

Kishimoto and Maehara studied and compared adherence to daily, weekly, and monthly doses of medication for osteoporosis patients.

The study revealed that monthly medication regimens had better patient adherence than weekly and daily medication regimens.

Researchers 3D printed biological material to create different types of cells and repeated the process in a complex way to replicate testable organs such as livers.

Researchers from Center for Nano-scale Systems (CNS) developed a method to 3D print a microchip replicating an organ to test experiments without putting anyone at risk.

This system established a geologic time scale for the emergence of North American land animals beginning with the late Cretaceous and continuing to the present. These ages, or stages when referring to the rock strata, were established using geographic place names to identify where the fossils were found.

This refers to the analysis of rock strata to determine remanent magnetization. It provides precise information about the polarity of the Earth’s magnetic field at the time of formation of the strata. The time interval between polarity reversals, or chron, is then used to accurately determine when the change occurred and date the strata.

They are members of the taxon Multituberculates and are not thought to belong to any of the groups of mammals living today. The anatomy of the pelvis suggests that they did not lay eggs but gave birth to very small, immature young. They had specialized teeth ideal for a vegetarian diet.

Note that the authors' work is built upon the findings of earlier research.

This is a way to determine the temperature based on the principle that the formation temperature of carbonate minerals is proportional to the relative abundance of 13C18O16O in CO₂. The clumped isotope thermometer is based on the measurement of the abundance of 13C-18O bonds in the mineral sample.

Multiple investigations have been performed to study the distributions and compositions of helium in a group of well-characterized diamonds. Studies during the 1980s made the scientists aware of the unusually ³He/⁴He ratio within individual diamonds. More recent explorations indicate that these diamonds are sources of radiogenic helium-4 and are generally found underneath the Earth’s mantle.

Conventionally, a high ³He/⁴He ratio is known to originate from the lower mantle region of the Earth. However, studies show that this is not always true. A new model proposed by scientists analyzed the seemingly inconsistent results and hypothesized that the high ³He/⁴He content may also arise from the upper mantle region.

The final tumor-specific method of generating immunity is to directly produce dendritic cells (the most common type of antigen-presenting cells) which display tumor antigens.

Another tumor-specific method of generating immunity is to modify tumor cells so that they produce a molecule which encourages the immune system's professional antigen-presenting cells (APCs) to take up molecules from the tumor cells. This means that APCs are better able to "train" T cells to recognize the signatures of the tumor.

Another tumor-specific method is modifying tumor cells so they become more similar to antigen-presenting cells. This allows T cells to recognize them more easily.

One such tumor-specific method of generating an immune response is to modify tumor cells so that they produce costimulatory molecules that enhance activation of T cells they come in contact with.

There are other methods of generating an immune response against cancer. Unlike this one, they are specific to the type of tumor, and require that the tumor cells be obtained and engineered in some way to become more visible to the immune system.

For the immune system to be able to respond to molecules on the surface of cancerous cells, these molecules are first presented on the surface of specialized immune cells. Through this antigen-presentation process, T cells able to respond to these molecules are activated and expanded.

The Institute for European Environmental Policy found that plastics make up 85% of beach litter worldwide, 61% of which are single-use plastics, such as those used in food packaging.

If cancerous cells express B7-1, the immune system is better able to respond to them and clear the tumor.

Another effect of CTLA-4 signaling is the programmed cell death of T cells. This is another way for CTLA-4 to dampen T cell responses.

Blocking CTLA-4 also increases T cell activation that happens as a result of encountering foreign invaders.

The inhibitory CTLA-4 receptor can be blocked by using soluble antibody. Blocking the effects of CTLA-4 allows T cells to activate and proliferate normally upon induction by anti-CD3.

CD3 is a co-receptor alongside the T-cell receptor. Together, they provide the primary signal of T cell activation. In this experiment, the scientists tried to add anti-CD3 antibody, which would normally result in T cell activation. However, the inhibitory effect of CTLA-4 wins out over this activation technique.

CTLA-4 competes with CD28 for binding to the B7 family of molecules.

The overall activation of T cells is also influenced by another type of secondary signal. In addition to stimulatory signals discussed above, T cells may also encounter inhibitory signals. The balance of these two signaling events results in the overall level of activation.

Introducing the genes for B7 molecules into tumor cells allows them to provide the secondary signal needed to activate T cells. This allows the immune system to respond to those modified tumor cells, as well as any future tumors of the same type that they encounter (even if the latter do not express B7).

The two-signal model of T-cell activation was confirmed when scientists found that specialized immune cells, called antigen-presenting cells, provide a secondary signal to T cells in order to activate them. This secondary signal comes from the interaction of the B7 family of molecules (on the surface of APCs) with the CD28 receptor (on the surface of T cells).

The mechanism of superlubricity at the sliding interfaces of materials is studied. Dienwiebel and co-researchers have investigated the superlubricity of graphite using a home-built frictional force microscope. They have also investigated the role of incommensurability in the origin of the ultralow friction of graphite.

Size plays a major role in superlubricity and many researchers have investigated the dependence of size of materials in friction reduction. Liu and co-workers reported one such size-dependent study of superlubricity on graphite. They have detailed the probability percentages of the superlubric state for different contact areas and also the mechanism of superlubricity (self retraction) of graphite layers.

The failure of moving mechanical assemblies due to friction and wear is a major concern in today's world. Different types of lubricants are employed to minimize friction. Though this helps to improve the lifetime of mechanical systems, researchers are on a quest to find a perfect lubricant to achieve the lowest friction and wear possible with no harmful additives or chemicals.

Research in superlubricity is gaining interest due to its potential applications in mechanical systems to reduce friction- and wear-related failures. Various researchers proposed different materials to achieve near-zero friction. Even though these materials show some promise, most materials are perfectly crystalline (which is not the case in real life) and the effect occurs mostly at the nanoscale regime.

Diamondlike carbon (DLC) film is a widely researched material to combat friction and wear in a number of applications, owing to its impressive tribological properties and low deposition costs. The tribological properties of DLC films sliding against each other are investigated and they are found to display super-low friction under specific conditions.

The structural analysis of graphene-wrapped nanodiamonds by electron energy-loss spectra (EELS) reported in this study is analogous to the previously reported structure of detonated nanodiamonds by other researchers.

The arcuate nucleus, a subregion of the hypothalamus, has been shown to be a very important brain region that controls food intake

Neurons within this region have been shown to control feeding in a reciprocal manner. POMC-expressing neurons are activated by satiety signals and reduce food intake whereas AgRP-expressing neurons are activated by starvation and increase food intake. These neurons have been proposed to be the neural substrate for satiety and hunger, respectively.

This paragraph details the pathway of fructose and glucose metabolism within cells. In normal cells this is how glucose and fructose are broken down and converted into energy. It is unknown how tumors metabolize these molecules and so the scientists move on to explore this in their next series of experiments.

Colorectal tumor fructose metabolism has been looked at in the past. In these studies the enzymes required to break down fructose were studied, rather than looking at fructose transporters as this paper did. The past research found similar results where tumors had higher levels of enzymes that break down fructose than normal human tissues did.

The same results seen in human studies looking at gastrointestinal discomfort after fructose consumption were recapitulated in mouse studies. In animal models scientists are able to more closely control variables and more inversely monitor outcomes. In this case they were able to directly measure fructose concentrations in the colon rather than relying on gastrointestinal symptoms. They found high concentrations of fructose in the colon after oral delivery, suggesting that the passive transporters in the intestine were unable to uptake fructose at levels higher than 1g per kg of weight.

A past study administered various amounts of fructose to people after fasting. They then assessed gastrointestinal symptoms that stem from fructose passing through into the intestines and colon undigested (malabsorption). They found that even 5g of fructose can lead to the saturation of passive transporters in the intestine. Ingestion of any amount of fructose over 5g will result in high levels of fructose in the colon.

Previous study of another genetically modified mouse model (where tumors were induced to grow mostly in the colon) demonstrated similar results. This suggests that this mouse model or genetic manipulation (APC deletion) itself is not somehow more sensitive to high fructose corn syrup than other mutations that lead to colorectal cancer. Comparing previous results increases confidence that any colorectal cancer tumors will respond to high fructose corn syrup in a similar fashion.

Scientists have found that in a high majority of colorectal cancers the APC gene is defective. This high correlation suggests that the APC gene is a major cause for the development of colorectal cancer and tumors.

Taking big data sets such as questionnaires or patient data, computational biologists can run statistical tests to look at correlations between variables. In this case data has shown that people who drink a lot of sugar-sweetened beverages (such as soda) tend to be more overweight and in men there was a significant correlation to developing colorectal cancer.

Prior to this research, studies primarily focused only on the transmitter expression during development. Is there a similar phenomenon in adult stages? The cervical ganglia are separated by denervation technique. The denervated ganglia were measured for the activity of substance P. Two-fold increase in substance P was observed in the ganglia compared to controls.

Two types of neurons—trigeminal neurons and nodose neurons—are discussed here.

Trigeminal neurons are derived from the neural crest. Epibranchial placodes help in the generation of the neurons found in the back of the brain/cranial nerves (or nodose). Hence, both neurons differ in embryonic origin.

Trigeminal neurons are derived from one source and hence they are homogenous. However, the epibranchial placode helps in the generation of several cranial nerves, namely hypoglossal and glossopharyngeal. This results in a heterogenous population.

As both sets of neurons differ in their embryonic origin and location in the brain, it is fair to state that the functions of these neurons to express catecholamines will also be different.

The conversion of norepinephrine to epinephrine is dependent on the mRNA synthesis and hormones released by the pituitary-adrenal axis.

Neurons in rat sweat glands can convert from catecholaminergic to cholinergic groups during development. This is evident from the lack of enzymes that are responsible for catecholamine synthesis.

These studies performed RNA sequencing to identify differences in RNA and gene expression in the autistic brain. They found that there are similarities in the kinds of genes that are changed in patients with autism.

D. Carstensen and others quantified the variability of interactions between plants and pollinators across different spaces. They found that these interactions vary greatly between different locations due to the abundance of species, which determined the likelihood of partners interacting with each other.

Lorenzo, Crouch, and Mazur found that using more interactive teaching methods improved conceptual understanding for all students in a college-level physics class and reduced the gap in performance between women and men, compared to classes taught in the traditional lecture-based way. Classes taught with the highest level of interaction eliminated the gender gap.

Schmader, Johns, and Barquissau found that women who identified more strongly with the stereotype that men are better than women at math were likely to be less confident about their own abilities and less likely to pursue math careers. They also found that women who believed the gender stereotype were more susceptible to its negative effects on math test performance.

Values affirmation can reduce the effect of stereotype threat for women taking a math test under laboratory conditions.

It has been shown that values affirmation can significantly reduce a person's physical response to a subsequent stressful situation.

Specifically, participants that performed a values affirmation task before undergoing a stress test produced less cortisol (a hormone that is released when we are stressed) than participants who did not get the intervention.

Previous work has assessed the gender achievement gap in college students taking introductory physics at the University of Colorado at Boulder.

Despite the use of teaching methods thought to reduce the gender achievement gap, there remained a difference between men's and women's test scores. Most of this gap could be attributed to differences in prior preparation (for example, men were more likely to take high school physics), but not all of the gap could be attributed to these factors.

Traveset and colleagues observed that bird-plant interactions on the Galápagos islands are highly generalized, meaning the birds developed relationships with a wide variety of plants, and vice versa. These broad interactions offer more opportunities for species to gain food. However, the authors also warn that these additional interactions promote the reproduction and survival of invasive plant species, at the cost of native species.

Using a blocking agent for nicotinic receptors, the binding of acetylcholine was blocked in the ganglia. This manipulation is similar to denervation technique and hence, the authors observed an increase in the activity of substance P.

The uptake of norepinephrine in these neurons remain unaffected. The neurons are capable of producing noradrenaline.

Noradrenergic neurons produce norepinephrine, the neurotransmitter expressed in rat sweat glands during postnatal stages of development. For a short period of time in development, the neurons lose the noradrenergic expression, but pick up the expression of acetylcholine.

Previously, researchers found that neurons in frog sympathetic ganglia are also depolarized by substance P, making them an appropriate model organism to study.

Cocaine is capable of producing LTP in several brain regions.

Similar to nicotine, SAHA also causes an increase in the expression levels of FosB

In cocaine-treated animals, LTP is impaired. SAHA helped in rescuing certain aspects of LTP in cocaine-treated animals.

This study shows that the key determinants for sequential drug use are the onset of age and the frequency of drug usage

The authors use DNA expression array techniques to identify genes that are modified by drugs of abuse and their mechanism of action.

FosB is shown to regulate gene expression in cocaine-treated animals.

CBP is instructed to FosB promoter to acetylate H4 histones, thereby regulating the expression of FosB gene in cocaine-treated animals

This paper shows that chromatin remodeling is a key mechanism that contributes to cocaine-induced synaptic plasticity.

Here the authors show that the cocaine can cause acetylation of histones via histone acetyl transferase (HAT) at a particular promoter site leading to chromatin acetylation and remodeling.

The authors show that the impairment in LTP and chromatin acetylation was observed in the animals.

By manipulating the CREB binding protein (CBP), some of these deficits were able to be restored. This suggests that LTP depends on the regulation of CBP.

Cocaine induces long term depression (LTD), a form of synaptic plasticity in the nucleus accumbens. This impairment in LTD causes deficits in the memory storage in this brain region.

After administering cocaine to animals, there is a decreased excitatory input from the prefrontal cortex to Nucleus accumbens.

This change in inputs leads to a lack of restraint on the inhibitory output from the nucleus accumbens to the ventral tegmental area, as the inhibitory output remains the same.

This leads to increased dopaminergic activity in VTA, leading to an increase in motor activity and in reward pathways.

This survey was conducted in the US to identify the usage and correlation of drugs of abuse. Questions were provided as a survey to the participating individuals, and the results are summarized in the report.

Examples of queries are age, drug usage, and frequency, lifestyle, smoking, and drinking frequency.

These tipping points are notoriously difficult to predict but can be recognized after the fact. Models are being developed to identify tipping points ahead of time, for example here.

There have been five mass extinctions on Earth in the past. These were caused by various natural events, from gamma-ray bursts to megavolcanic eruptions to meteor strikes. During each mass extinction, species diversity diminished significantly in a short period of time. Each mass extinction was followed by the evolution of novel forms of organisms that transformed their habitats in new ways.

Most scientists agree that we are currently in the 6th mass extinction event, this one largely caused by human activities such as climate change, habitat loss/fragmentation, pollution, invasive species, and human consumption/overexploitation.

This top-down forcing by disease and loss of herbivores has also been linked to the complex carbon cycle in the region:

http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1000210

In this case, the apex predators have been overhunted by humans for bushmeat, for trophies, or as pests to their livestock.

Because of overuse of antibiotics in livestock, the vulture population declined, leading to more scavenging by feral dogs of carcasses throughout the region. As the dog populations grew, and due to their proximity to humans, the risk of transmission of rabies to humans has increased greatly.

In this case, researchers found that certain types of predatory fish, while consumers of mosquito larvae, also regularly consumed the mosquito's main predators, leading to increased malaria infections.

Researchers found that after wolves were reintroduced to Yellowstone, there was a net decline in soil nitrogen, likely due to fewer large herbivores. In addition, the spatial nature of nitrogen renewal changed due to new use patterns by the herbivores.

Predatory sea stars regularly graze the rocky intertidal regions and are not prey-specific. Their grazing opens new substrate for multiple species, preventing the dominant species from colonizing all of the rocks.

It was observed that the loss of coyotes as an apex predator control on smaller vertebrate predators, along with habitat fragmentation, led to trophic cascades in the ecosystem.

Anorexia induced by dietary deficiency in a single indispensable amino acid was found to induce expression of c-fos—a protein known to be present in active neurons—in the PSTh.

Zahodne, Amami, and Novakova studied Parkinson's patients and found that many subjects exhibited binge-eating behavior. Those that had received deep-brain stimulation of the subthalamus were more likely to display this behavior.

Kendrick and colleagues found that the neurotransmitter GABA was increased in the ZI in sheep when the animals were presented with and ingested food.

The ZI has been shown to be important for food intake that occurs in response to low levels of blood glucose. Rats with ablated ZI eat less food under these conditions.

The lateral hypothalamus is a region neighboring the ZI. Stimulation of this site has been shown to substantially increase food intake and is also hedonic.

Nirenberg and co-workers saw that poly A was not decoded, specifically at low pH (acidic environments). At low pH, poly A is double stranded. These results suggest that the residues may need to be exposed—that RNA must lack secondary structure—to be decoded.

Nirenberg and Matthai discovered that "special RNA"—now called tRNA—was critical to protein synthesis. A protein could only grow with enough tRNA available, demonstrating that tRNA was a critical material to generate proteins.

To hear a contemporary scientist give an in-depth account of protein synthesis, watch Johns Hopkins University's Rachel Green detail the process on this iBiology video.

Lippman and Von Ehrenstein showed that genetic material (mRNA) from a mammal could be decoded with genetic material (tRNA) from a bacteria to form the protein hemoglobin. Because hemoglobin is not found naturally in bacteria but is found naturally in mammals, this was a remarkable result: The biological material of a bacterium decoded mammalian genetic material!

The result suggests that vastly different biological species share a genetic language. This is strong evidence that the code is universal.

See a visualization here.

Tsugita used an acid (nitrous acid) to chemically mutate RNA. The acid most often changed cytosine bases into uracil bases. The mutant genetic material encoded a different amino acid sequence than the unmutated, or native, form.

Introgression, the movement of a gene from one species into the gene pool of another, has been known to speed up a population's response to an evolutionary selective pressure. It does this by increasing genetic diversity.

Grant and Grant documented recurring introgressive hybridization between medium ground finches and small ground finches.

HMGA2 is a gene that plays a role in transcribing HMGA proteins. These proteins are associated with chromatin, the substance that makes up chromosomes and can consist of DNA, RNA, and proteins.

Pfannkuche and colleagues (2009) found that HMGA2 is an important factor in embryonic stem cells and seems to magnify other factors, such as the regulation of body height in humans, the repression of certain genes, and several other functions.

Stuart and Losos (2013) found that just over 6% of the cases they reviewed that highlighted character displacement actually showed strong examples. However, one study not only documented ecological character displacement, but also showed it happening in real time. This was the long-term experiment of Darwin's finches by Grant and Grant (2006).

Darwin states in The Origin of Species that the differences between species is caused by divergence. It is this divergence that acts to minimize the competitive interactions between similar populations.

Brown and Wilson (1956) later argued that this concept (they called it character displacement) was a common part of geographical speciation. They explained that displacement happened most often as a product of genetic and ecological interaction when species first met.

This is an advantage over the traditional CRISPR/Cas9-mediated genome editing. CRISPR/Cas9 uses the cell's machinery to make changes, so it is efficient only in actively dividing cells.

Moreover, we can compare the REPAIR system to DNA cytidine base-editors (BE). The BE system has been modified to prevent cellular DNA repair processes that are triggered by Uracil (U) bases in DNA. The BE system, in any form, still relies on DNA repair machinery to propagate the edit. RNA editing does not. 

Check out the schematic below for more information on the BE editing paths.

There are two main approaches for the inserting of exogenous genetic material into cells: non-viral and viral.

Non-viral techniques such as transfection with DNA-liposomes can be used for almost any construct, and are relatively easy to use. Some therapeutic companies are looking at lipid nanoparticles for ribonucleoprotein (RNP) delivery to the liver. The authors of the paper used liposome transfection in all of the preceding experiments they describe here. However, this method is inappropriate for in vivo (live) delivery because of its non-specificity and high toxicity.

An alternative approach is to use viral delivery. This strategy utilizes the natural ability of viruses to infect cells and integrate viral DNA into cellular DNA. A part of the viral genome is replaced with a desired sequence, and then cells are infected with the modified virus. When viruses insert their DNA into the cellular DNA, the desired sequence is added. Viruses are very specific and use only certain molecules to enter the cell, so this method is useful for controlling the type of cell that receives exogenous DNA. However, precautions must be taken to make sure the virus does not go out of control and that the cell's immune response does not destroy the virus before it delivers the DNA.

The group that described targeting preferences of Cas13 suggested that PFS should be used for Cas13 instead of PAM, since PAM is used for Cas9. Additionally, PFS is different than the PAM because the PAM is used for discriminating self from non-self sequences. The PFS is not used for that as there is no concern for self targeting when targeting RNA molecules. Therefore, the PFS is just some sequence preference of Cas13.

ADAR enzymes bind to adenosine and convert them to inosine by deamination, or the removal of an amino group from the molecule. In RNA, inosine is structurally similar to guanine (G), so it can form a base pair with cytidine (C). ![] (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953425/bin/nihms234588f1.jpg)

Source: Nishikura, K. (2010). Functions and Regulation of RNA Editing by ADAR Deaminases. Annual Review of Biochemistry 79, 321–349. http://doi.org/10.1146/annurev-biochem-060208-105251

The authors developed a technique called SHERLOCK (Specific High-Sensitivity Enzymatic Reporter UnLOCKing) and successfully used it to detect Zika and dengue virus RNA, pathogenic bacterial DNA, and mutations in human DNA. 

Both RNA and DNA molecules can be used as a starting material. First, they are converted to DNA and amplified by in vitro transcription into RNA. Next, Cas13 finds target RNA sequences and emits a signal that researchers use to detect the presence of certain RNA molecules.

See the creators of SHERLOCK talk about how it works and potential applications in this video.

The application of macroscopic laws of friction to the nanoscale region remained controversial. Mo and his team used molecular dynamics simulations to study friction laws in dry nanoscale contacts. They have investigated the effect of the number of atoms in chemical contact in friction and reported on the relationship between contact area and friction force in the nanoregime.

MOF-801 was selected for this study because it adsorbs a large amount of water even when a small amount of water is present in the atmosphere, as is often the case in arid regions such as deserts.

To date, the existing systems for water-harvesting cannot be efficiently used in environments with low relative humidity levels.

Zeolites and silica gels are minerals made mainly of aluminum and silica. They also have porous structures which allow them to trap molecules within their cavities. This property makes them useful as adsorbants for molecules such as water.

It has been found that a variety of porous materials can trap water from air in small cavities within its structures. This capacity is dependent on the material. For the water harvesting process to be practically usable, the material needs to be able to absorb a large amount of water even when only a small concentration of water is present in the atmosphere (low relative humidity).

There has been a lot of interest in developing a system capable of harvesting water from air and fog. However, systems developed so far either require a very large amount of water in the air (high humidity), which is not suitable for dry regions, or need a large amount of energy to allow condensation of the water. These systems are therefore neither usable in dry conditions nor economically viable. In the "Related Content" tab, check out a response the paper authors wrote that addresses these issues.

Materials with perfect atomic structures and long periodicity are traditionally sought for superlubricity. Carbon compounds such as carbon nanotubes, graphite, and graphene are investigated for this purpose. One concern is the difficulty in attaining sustainable superlubricity at the engineering scale.

The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. The IPCC reviews and assesses the most recent scientific, technical, and socioeconomic information relevant to the understanding of climate change.

This study utilized the 1995 IPCC report. Updated versions come out every few years, with the 5th and most recent IPCC report published in 2014.

For more information about the IPCC, visit:

https://www.ipcc.ch/index.htm

Thompson and Wallace did not directly state that the North Atlantic Oscillation (NAO) may be part of the Arctic Oscillation (AO), but they did mention that these oscillations share many similar characteristics.

Thompson and Wallace found that changes in wintertime sea level pressures above the high northern latitudes of Europe and Asia was part of an AO, distinct from the NAO. The AO "resembles the NAO in many respects; but its primary center of action covers more of the Arctic." This means that there are aspects of the climate features which can distinguish between these two climate phenomenon.

Reynolds helped develop a method for converting satellite data into accurate temperature measurements. One of the problems with satellite data is that it has to be corrected for anomalies such as dust and aerosols, which can make satellite measurements slightly different from reality. It is possible to get usable temperature data from satellites by accounting for this and correcting the data.

Dickenson et al. analyzed North Atlantic water temperatures and proposed a theory that the variability in deep ocean mixing is related to the regional climate pattern (the North Atlantic Oscillation).

The restart of deep water mixing in the Labrador Sea just southwest of Greenland coincides with a change in phase of the North Atlantic Oscillation. This study notes that climate has a strong impact on the extent of deep water formation (convection) in the North Atlantic Ocean.

There are also time series records of land temperatures. For the last 100 years, many countries have recorded increasing temperatures.

To learn more, check out this Carbon Brief video created by Antti Lipponen: https://www.youtube.com/watch?v=-yIHxOui9nQ

There are many assumptions that go into creating global climate models. This is because these models must simulate complex interactions between the atmosphere, oceans, land surface, ice, and the sun.

However, as information from real-world sources such as satellites and other measurements accumulates, climate models are constantly refined to increase their power, usefulness, and accuracy. Improved climate models that have been released since this paper was published have made the concern about a sudden increase in atmospheric carbon dioxide less of an issue.

For more about climate models visit Skeptical Science: https://www.skepticalscience.com/climate-models-basic.htm

Hansen et al. discovered that, between 1979 and 1996,Earth received somewhere between 0.5 to 0.7W/m² of extra energy. As energy can not be created nor destroyed, this extra incoming energy remains in the Earth system and contributes to climate change. 

Warm, salty seawater from the mid-latitudes is transported northward by the Gulf Stream. Once it reaches the higher latitudes near the Labrador Sea, cold air temperatures chill the seawater. This salty, cold seawater is denser than warmer waters, so it sinks and becomes the formation zone for North Atlantic deep water.  

This density-driven process of deep ocean circulation is sometimes referred to as Thermohaline Circulation. "Thermo" refers to temperature and "haline" refers to how much salt the water contains. Both temperature and salinity are key components in determining density.

The North Atlantic is one of the few regions in the world where deep water formation occurs.

The waters of the Mediterranean are extremely warm and have high levels of evaporation, causing the sea to be very salty. While Mediterranean waters are typically warmer than in the Atlantic Ocean, the high salinity causes Mediterranean waters to be slightly more dense than surface waters of the Atlantic. Because of this, water that exits the Mediterranean into the Atlantic sinks and flows out into the Atlantic at roughly 1000 m depths.

For more information about the Mediterranean Outflow and to see real Argo float depth profiles visit: http://www.euroargo-edu.org/floatdata.php?float=6901631

Because the Earth is a spinning sphere, certain wind and ocean currents have formed that make it useful to think of the Equator as a boundary between North and South Pacific waters.

To learn more about how ocean currents are driven by wind, water density differences, and tides, watch this video from the National Oceanographic and Atmospheric Administration (NOAA): https://oceanservice.noaa.gov/facts/current.html

The ocean is a major carrier of heat. As warm surface currents move towards the poles, they slowly release heat. Once cold and dense enough in the high latitudes, this water sinks and the deep ocean currents carry cold waters to lower latitudes.

Figure from Thompson and Seiber (2011, IJBC).

Due to Earth's tilt, the tropics receive more incoming solar radiation than the poles do, so there is excess warming in the lower latitudes. Wind and ocean currents carry this heat towards the higher latitudes.

This figure shows the balance between average net incoming solar radiation (shortwave) and the heat emitted by earth (longwave radiation) from 90° North to 90° South.

Read more about earth's energy balance here: http://www.physicalgeography.net/fundamentals/7j.html

The authors of this paper agree with Bork and colleagues' original proposition that enterotypes are "densely populated areas in a multidimensional space of community composition." However, they argue that these enterotypes are not discrete but rather overlapping microbial configurations.

There is a huge variety of diseases associated with bacteria. The connections between bacteria and pathologies are only beginning to be uncovered, in part due to research into the microbiome.

To get an overview of the types of diseases caused by bacteria, check out this resource from the University of Utah: https://learn.genetics.utah.edu/content/microbiome/disease/

O'Toole and colleagues found that changes in the gut microbiome composition were associated with chronic conditions like obesity and inflammation. They were able to show that these changes were partially driven by diet in aging populations.

Gordon and colleagues conducted a similar gut microbiome study in 2012 but focused on how they differed across populations, comparing healthy individuals from Venezuela, Malawi, and the United States.

The Human Microbiome Project launched by the U.S. National Institutes of Health was one of the first initiatives to research the impact of our microbiomes on human health and disease. This was one of the first large scale projects based on 16S rRNA sequencing and has become the basis of important database systems for current metagenomic studies. The goal of this study was to establish a core human microbiome in healthy individuals and observe how it changes during different disease states.

The FGFP and the LLDeep projects share similar sequencing approaches and goals to the Human Genome Project, with a distinct focus on the gut microbiome and its links to lifestyle and health.

See the supplemental figure below.

This type of speciation could be rare, but as it is also hard to detect, it may be less rare than currently estimated.

Hybrid speciation in plants that includes increasing the chromosome number is known to occur.

Neurons in the dish were exposed to electrical activity that can cause depolarization of membrane. It is shown that these neurons are noradrenergic while the non-neuronal cells show an expression of acetylcholine.

Different species may coexist in the colon differently to reduce competition and extinction in either species as several components (nutrients) will be differentially available throughout the colon with changing transit time.

Researchers, like Bokulich and colleagues, had previously demonstrated that birth mode (i.e., vaginal, caesarian) affected the gut microbiome in adults. This study was not able to demonstrate that these differences were still present later in life.

Microbiome assessments can have different goals. The U.S. National Institutes of Health Human Microbiome Project (HMP) aimed to characterize the microbial communities from 300 healthy individuals across different sites on the human body; whereas, the Flemish Glut Flora Project (FGFP) targeted a general sample of the population.

Read more: https://commonfund.nih.gov/hmp

Bork and colleagues proposed that humans have three different gut types based on the most abundant bacterial taxa. The types of bacteria present are independent of an individual's age, sex, or nationality but they found some correlation between some characteristics and bacterial function. For example, the abundance of Bacteroides, which break down carbohydrates, was found to increase with age.

In October 2010, Google announced that its self-driving vehicles had collectively driven more than 200,000 kilometers (about 124,000 miles) on actual roads in California.

In 2007, the Defense Advanced Research Projects Agency (DARPA) hosted the DARPA Urban Challenge, which called for self-driving vehicles that could navigate a realistic city environment, and obey traffic rules while doing so.

The requirements for the challenge included passing slowly moving cars, merging into fast traffic, and parking in a parking lot.

Researchers have developed a new set of software that decodes ultrasonic rat vocalizations, including those that come from tickling!

Check it out with this video from Verge Science.

Dintzis and Naughton demonstrated that a protein is synthesized from one end of the amino acid chain to the other, like stringing beads on a necklace one by one.

If you are interested in science communication, annotation, or just passionate about connecting students to #ActualLivingScientists, come see us!

This phenomenon has been observed on Daphne Major in several cases. It is a possible factor in causing hybridization events.

There is a naturally occurring variability in rats' urge to consume alcohol that is correlated with the levels of NPY in their brain. In mice, artificially increasing the amount of NPY in the brain leads to higher consumption of alcohol and reduced sensitivity to the intoxicating effects of alcohol (as well as vice versa). This is very similar to what has also been shown in flies (see reference in previous paragraph).

Injection of NPY into specific parts of the mouse brain can trigger intense eating or inhibit sexual drive.

When the activity of the NPF circuit is reduced below normal, flies are less sensitive to the intoxicating effects of alcohol (i.e. they exhibited fewer signs of "drunkenness"). The vice versa has also been observed to be true.

The authors will argue in this paper that they have discovered an explanation for how addictive substances/experiences can affect a fly's behavior and neurobiology. Understanding the effect of reward on an organism is important because it can lead to a better understanding of addiction (which can be seen as an abnormal response to a rewarding substance).

The rewards the authors use here are mating (sex) and ethanol (alcohol). The authors cite previous research to show that flies find alcohol to be rewarding and that they demonstrate addictionlike behaviors in pursuit of alcohol. These distinctions are important to demonstrate the similarities between fly and human responses to alcohol. They then build upon this previous research for their own experiments.

An important advantage of Cas13 over Cas9 is that it does not have a PAM or PFS that is required for it to target a specific site. To expand the number of sequences that Cas9 can target, researchers must use Cas9 proteins from different species (which have different associated PAM sequences). This can complicate the development and testing of gene editing systems that use Cas9.

In terms of precision, i.e., on-target editing, we can compare REPAIR to other base editors.

For instance, cytidine editors contain the cytidine deaminase APOBEC1 and convert C-G pairs to A-T pairs. The activity of APOBEC1, directed by Cas9, is not restricted to only one C but extends for several bases away from the PAM sequence. Recent work has demonstrated that the editing window of APOBEC may be reduced to 1-2 nucleotides by modifying of the deaminase.

Similarly, the precision of ADAR2 may be increased by placing a C across from the target A, creating a mismatch that is ideal for ADAR2 editing.

The authors of the paper looked at the crystal structure of the ADAR deaminase with the RNA duplex and predicted that ADAR might also operate on RNA-DNA duplexes. Later, they experimentally confirmed this prediction.

The RNA molecule is transcribed in the nucleus and then exported to the cytoplasm. It can be recognized and cleaved by Cas13 at any moment along this way.

Previously, the authors used nuclear localization sequences (NLS) and nuclear export sequences (NES) to determine at what point during the transcription and export process Cas13 is most efficient. They tested knockdown efficiency of LwaCas13a with either NLS or NES tags.

They found that constructs with a nuclear localization sequence (NLS) were most efficient. However, this observation cannot be generalized to all Cas13 orthologs, which must be tested individually.

Previous work has shown that ADAR works better when an RNA molecule contains a mismatch at a target site. This may be because it makes it easier for the deaminase to flip the target base, which has to happen for editing. Panel B shows what base flipping looks like: Zheng, Y., Lorenzo, C., & Beal, P. A. (2017). DNA editing in DNA/RNA hybrids by adenosine deaminases that act on RNA. Nucleic Acids Research, 45(6), 3369–3377. http://doi.org/10.1093/nar/gkx050

Similar to the gut cells, the nerve ganglia of the rat also show transient expression of catecholamine during development.

This study focused on the neurotransmitter expression changes in the embryonic stages of development. At embryonic day 11.5, the neurons express the attributes of noradrenergic cells. However, these traits are lost by embryonic day 14.5. The uptake system for norepinephrine remains intact in these neurons.