Culture

Lianhuaqingwen (LHQW) capsule, a herb medicine product, has been clinically proved to be effective in coronavirus disease 2019 (COVID-19) pneumonia treatment. However, human exposure to LHQW components and their pharmacological effects remain largely unknown. The authors of this study aimed to determine human exposure to LHQW components. Based on the human exposure analysis, several ACE2 binding components with good enzyme inhibitory effects were screened out by ACE2 biochromatography. The results obtained by the authors demonstrated chemical and biochemical evidence for exploring molecular mechanisms of therapeutic effects of LHQW capsule for the treatment of COVID-19 patients based on the components exposed to humans.

The research also demonstrated the utility of the human exposure-based approach to identifying pharmaceutically active components in Chinese herb medicines.

COLUMBUS, Ohio - New research shows that when vampire bats feel sick, they socially distance themselves from groupmates in their roost - no public health guidance required.

The researchers gave wild vampire bats a substance that activated their immune system and made them feel sick for several hours, and then returned the bats to their roost. A control group of bats received a placebo.

Data on the behavior of these bats was transmitted to scientists by custom-made "backpack" computers that were glued to the animals' backs, recording the vampire bats' social encounters.

Compared to control bats in their hollow-tree home, sick bats interacted with fewer bats, spent less time near others and were overall less interactive with individuals that were well-connected with others in the roost.

Healthy bats were also less likely to associate with a sick bat, the data showed.

"Social distancing during the COVID-19 pandemic, when we feel fine, doesn't feel particularly normal. But when we're sick, it's common to withdraw a bit and stay in bed longer because we're exhausted. And that means we're likely to have fewer social encounters," said Simon Ripperger, co-lead author of the study and a postdoctoral researcher in evolution, ecology and organismal biology at The Ohio State University.

"That's the same thing we were observing in this study: In the wild, vampire bats - which are highly social animals - keep their distance when they're sick or living with sick groupmates. And it can be expected that they reduce the spread of disease as a result."

The study was published today (Oct. 27, 2020) in the journal Behavioral Ecology.

Ripperger works in the lab of co-lead author Gerald Carter, assistant professor of evolution, ecology and organismal biology at Ohio State. The two scientists and their co-author on this paper, University of Texas at Austin graduate student Sebastian Stockmaier, are also affiliated with the Smithsonian Tropical Research Institute in Panama.

Carter and Ripperger have partnered on numerous studies of social behavior in vampire bats. Among their previous findings: Vampire bats make friends through a gradual buildup of trust, and vampire bat moms maintained social connections to their offspring even when both felt sick.

For this work, the researchers captured 31 female common vampire bats living inside a hollow tree in Lamanai, Belize. They injected 16 bats with the molecule that induced the immune challenge - but did not cause disease - and 15 with saline, a placebo.

After returning the bats to their roost, the scientists analyzed social behaviors in the colony over three days, including a "treatment period" from three to nine hours after the injections during which the researchers attributed behavior changes to the effects of treated bats feeling sick.

"We focused on three measures of the sick bats' behaviors: how many other bats they encountered, how much total time they spent with others, and how well-connected they were to the whole social network," Carter said.

On average, compared to control bats, the sick bats associated with four fewer groupmates over the six-hour treatment period and spent 25 fewer minutes interacting per partner, and the time any two bats spent near each other was shortest if the encounter involved at least one sick bat.

"One reason that the sick vampire bats encountered fewer groupmates is simply because they were lethargic and moved around less," Carter said. "In captivity, we saw that sick bats also groom others less and make fewer contact calls. These simple changes in behavior can create social distance even without any cooperation or avoidance by healthy bats. We had previously studied this in the lab. Our goal here was to measure the outcomes of these sickness behaviors in a natural setting.

"The effects we showed here are probably common in many other animals. But it is important to remember that changes in behavior also depend on the pathogen. We did not use a real virus or bacteria, because we wanted to isolate the effect of sickness behavior. Some real diseases might make interactions more likely, not less, or they might lead to sick bats being avoided."

Although the study did not document the spread of an actual disease, combining the social encounter data with known links between exposure time and pathogen transmission allows researchers to predict how sickness behavior can influence the spread of a pathogen in a social network.

Clearly identifying each bat's behavior in the colony's social network was possible only because the proximity sensors - miniaturized computers that weigh less than a penny and fall off within a week or two - took measures every few seconds of associations involving sick or healthy bats or a combination of the two. Visualizations of the proximity sensors' recordings showed growth in the number of connections made in the colony's social network from the treatment period to 48 hours later.

"The proximity sensors gave us an amazing new window into how the social behavior of these bats changed from hour to hour and even minute to minute during the course of the day and night, even while they are hidden in the darkness of a hollow tree," said Ripperger, who is also a visiting scientist at the Museum of National History in Berlin, Germany.

CHAPEL HILL, NC - MicroRNAs (miRNAs) are evolutionarily conserved small noncoding RNAs - bits of genetic code that serve as critical gene regulators in many aspects of biological processes important for human health. Due to their essential roles in gene regulation, miRNAs are tightly regulated, and abnormal miRNA expressions have been linked to cancer, neurological disorders, cardiovascular diseases, and other diseases.

Understanding how miRNAs are regulated has been the focus of intense recent study. Over the years, scientists have discovered multiple protein regulators of miRNA biogenesis cellular pathways, and it is often perceived that these protein factors act on largely passive miRNA processing intermediates to direct their maturation. Now, the lab of Qi Zhang, PhD, associate professor in the UNC Department of Biochemistry and Biophysics, discovered a new RNA-centric mechanism by which miRNA processing intermediates can play direct, active roles in regulating miRNA biogenesis.

These findings, published in the journal Nature Chemical Biology, unveil that a 'hidden' layer of regulation by which the intrinsic dynamic ensemble of miRNA processing intermediates can direct the outcome of important biological processes in response to environmental and cellular stimuli in the absence of protein factors. If these processes go awry, then disease could result. Understanding the roles of miRNAs in disease is a needed step in finding new routes to better therapeutics.

MicorRNA-21 (miR-21) is involved in the creation, progression, metastasis of cancerous tumors, and it is involved in cell survival. When Zhang's lab studied miR-21 using NMR relaxation dispersion - an advanced imaging technique capable of detecting sparsely populated transient states that often evade conventional detection techniques - they found the precursor of miR-21 exists as an ensemble of dynamic conformational states, which is surprisingly sensitive to the acidity of the environment.

They discovered that, across physiological conditions, about 1 - 15% of the miR-21 precursor carries one additional proton, the smallest chemical modification known as protonation. With a lifetime of approximately 0.8 milliseconds, this protonated state sequesters a key residue into a new structure that substantially enhances the efficiency of processing the precursor into mature miR-21.

With these powerful "imaging" techniques, scientists can now unveil transient RNA states as the 'hidden' layers of regulation, including a fleeting riboswitch state important in controlling gene transcription - a state the Zhang laboratory discovered in 2017.

"We think these techniques add more promise for new strategies to create RNA-targeted therapeutics," said Zhang, a member of the UNC Lineberger Comprehensive Cancer Center. "And that is our goal; we need better targeted therapies for many diseases including cancers."

CLEVELAND - An international team of researchers led by Cleveland Clinic's Lerner Research Institute has performed for the first time a wide-scale characterization of missense variants from 1,330 disease-associated genes. Published in Proceedings of the National Academy of Sciences, the study identifies features associated with pathogenic and benign variants that reveal the effects of the mutations at a molecular level.

"Our study serves as a powerful resource for the translation of personal genomics to personal diagnostics and precision medicine, and can aid variant interpretation, inform experiments and help accelerate personalized drug discovery," said Dennis Lal, PhD, assistant staff, Genomic Medicine, and the study's lead author.
Recent large-scale DNA sequencing efforts have detected millions of missense variants, where mistakes in the DNA code change the amino acid (molecular building block of a protein) makeup of proteins. Some of these variants are pathogenic, meaning they alter the structure and function of a protein in a way that leads to disease, while others are benign with no impact on health. The vast majority, however, are considered variants of uncertain significance because their effects remain unknown.

While methods to predict variant pathogenicity exist, they do not elucidate why some variants are more or less likely to cause disease than others or establish their functional impact. Additionally, pathogenic and benign variants can co-exist in almost every disease-associated gene. As such, gaining a better understanding of the mechanistic differences between benign and pathogenic variants will be a critical next step in the development of novel therapies for genetic disorders.

Considering that a protein's function is closely linked to its three-dimensional structure, in this study the research team identified and compared the protein features of amino acids affected by pathogenic versus benign missense variants. Features that are more frequently mutated in pathogenic variants compared to benign variants (3D mutational hotspots) are likely crucial to protein fitness and thus could help explain the molecular determinants of pathogenicity.

Looking at 1,330 disease-associated genes, the researchers analyzed a set of 40 features and found that 18 were significantly associated with pathogenic variants, 14 were significantly associated with benign variants and the remaining eight had no significant association with any variant type.

"By considering genetic variation in the context of proteins' three-dimensional organization, we present for the first time an atlas of molecular properties of pathogenic mutations that addresses the differences between benign and disease-causing mutations," said Lal. "This study focused on 1,330 genes associated with rare types of genetic disorders, so we are currently extending our project to look at more genes and milder disorders."
Data from this study (including precomputed P3DFiDAGS1330 and P3DFiProteinclass values for every possible amino acid exchange in proteins encoded by 1,330 disease-associated genes, along with the explicit listing of the 3D features of the altered site as the rationale for the index) is available through the dedicated web server MISCAST.

An environmentally friendly and sustainable synthesis of "heavyweight" polymers with very narrow molecular weight distributions is an important concept in modern polymer chemistry. Thanks to a new photoenzymatic process, Chinese researchers have been able to increase the range of possible monomers. As reported in the journal Angewandte Chemie, the researchers were able to obtain well-defined linear and star-shaped polymers with ultrahigh molecular weights.

Because many polymer properties depend heavily on molecular weight, it is desirable to have as narrow a molecular weight distribution as possible. Precision polymers with ultrahigh molecular weights (> 1 t/mol) would be interesting candidates for high-performance elastomers, low-concentration hydrogels, photonic materials, durable coatings, and flocking agents. However, such heavyweight polymers are not easy to produce with a uniform distribution of molecular weights. The radical polymerizations in widespread use are especially difficult to control in this respect. Modern methods, such as RAFT polymerization (RAFT: reversible addition-fragmentation chain transfer) offer a significantly higher degree of control by keeping the concentration of reactive radicals very small. A special agent reacts reversibly with the growing polymer chains to form a nonradical species. Whenever the intermediate dissociates, new active radicals are formed. This slows the reaction and results in longer, more uniform polymer chains.

Ultraheavy polymers with narrow weight distributions were previously only attainable from conjugated monomers, meaning compounds with at least two C=C double bonds separated by a single bond. It has never been possible to make such polymers from nonconjugated polymers whose vinyl group (-CH=CH(2)) is bound directly to a noncarbon atom.

Zesheng An (Jilin University, Changchun) and Ruoyu Li (Shanghai University) have overcome this challenge with a simple, environmentally friendly, RAFT polymerization that is based on enzymatic photocatalysis. The enzyme glucose oxidase (GOx) oxidizes glucose with oxygen, reducing the flavin-containing cofactor FAD to FADH(?). The latter acts as a photocatalyst when irradiated with visible light, starting the radical chain reaction. GOx consumes the oxygen present in the solution--another advantage because oxygen disrupts conventional radical polymerizations and must be removed beforehand. The chain propagation agents they use are xanthates (sulfur-containing carboxylic acid derivatives).

The researchers attained well-defined linear and star-shaped polymers in nearly quantitative yield, as well as various copolymers with previously unattainable uniform ultrahigh molecular weights, starting from nonconjugated monomers. The reaction, which offers outstanding control over composition, molecular weight, and architecture, is simple to carry out and takes place under mild conditions (10 °C) in water.

LAWRENCE -- Politicians discuss the ins and outs of health care while trying to win votes, but for some Americans, policymakers do not seem to be listening. University of Kansas researchers have published a study about perspectives of individuals with disabilities on health care policy, and respondents overwhelmingly stated access to health care is vital and they would like policymakers to pay more attention to their needs.

Scholars analyzed data from 35 phone interviews and survey responses from more than 475 individuals with disabilities about health policy. While the respondents largely reflect the political opinions of American society at large, they tended to agree that health care should be viewed as a human right and that feelings of social exclusion and stigma inform what they would like to tell officials who make health policy in the United States.

"We found that people with disabilities are marginalized and stigmatized and that policymakers don't listen to them," said Sarah Smith, a doctoral candidate in sociology, graduate research assistant at KU and lead author of the study. "They also felt that access to health insurance was important in order to be able to take part in society and that policymakers did not consider how the policies they make affected their lives."

The study, published in the Journal of Disability & Policy Studies, was co-written by Smith; Jean Hall, professor of applied behavioral science and director of KU's Institute for Health & Disability Policy Studies, and Noelle Kurth, senior research assistant at the institute. The interviews and surveys revealed five key themes about health policy perspectives among people with disabilities.

Access to health insurance and health care is critical for their ability to participate in society

They felt that politicians did not understand or prioritize the needs and experiences of people with disabilities

Participants used a variety of arguments why policymakers and society should care about people with disabilities

They felt access to health care is a human right or moral imperative

Participants expressed largely positive views regarding the Affordable Care Act.

Respondents nearly uniformly reported how important employment was to their lives in terms of financial security, access to health insurance, not depending on state programs for health coverage and for personal dignity. However, they also faced many barriers to employment, especially those living in states that have not expanded Medicaid who tend to lose eligibility when they are employed.

"Employment is a key component of being part of society and a big part of personal identity," Smith said. "But it can be very hard to access, and most health insurance is tied to employment, which also makes insurance difficult to access, especially if you're not employed full time."

Many study participants also shared that policymakers do not consider the needs of constituents with disabilities.

"I hear politicians on the TV talking about me as if I am the cause of the budget deficit," one respondent said. "They seem to lump us into a group of people--well, not people: 'You're the budget deficit, you're this, you're that,' instead of saying, 'These are people who need care.' Maybe the number one thing, then, is an attitude change. You're not dealing with line items on a budget; you're dealing with what real people need."

Previous research has shown political leanings of people with disabilities are representative of those of American society at large, and participants used a variety of arguments for a matter they agreed on: Policymakers should care about individuals with disabilities. The arguments included that no one chooses to be disabled, anyone can become disabled, better health care access will lead to more productive society, all individuals should matter to policymakers as human beings and that politicians should make the health care policy for all like what they want for themselves and their families.

Health care was viewed as a human right, not something that should only be available to certain members of society, the findings showed.

"Policymakers already know that restricting access to health care has outcomes that range from loss of income to loss of life," one participant said. "True access means that all citizens, regardless of their ability to pay, have access to the same range of services. Like water and an unpolluted environment, health services are essential to life, liberty and the pursuit of happiness."

The study's participants also expressed largely positive opinions about the Affordable Care Act. Many reported that they still struggled with health care costs but were at least able to get health insurance through the act. Primarily, the law's health insurance premium subsidies, coverage for preexisting conditions and Medicaid expansion were important to study participants.

Taken as a whole, the results show the connections among disability stigma, health policy and politics. Previous research has shown that people with disabilities face barriers to political participation, similar to those they face with employment and participation in society, and as a result their voices are often underrepresented in health policy discussions, even though their lives are greatly affected by the policies enacted. As key participants in programs such as Medicare, Medicaid and Social Security, the population can provide vital insight into the functioning and outcomes of those programs, the authors wrote. As America's population ages and the COVID-19 pandemic affects more people's long-term health, new complications to health care access can be expected, which the authors plan to address in future research.

"This is a population that knows a lot about health policy, because they have to know a lot about navigating insurance and health care systems. Policymakers should listen to them," Smith said.

Low muscle quality and quantity are both predictive of poor outcomes in colon resection surgery, according to a new study published in JAMA Surgery.

Carla Prado, a researcher in the University of Alberta's Faculty of Agricultural, Life & Environmental Sciences, and her team followed 1,630 patients who received a diagnosis of Stage I to Stage III colon cancer. The researchers examined various outcomes including length of hospital stay, need for readmission and mortality in patients with colon cancer following colon resection surgery.

They found that low muscle mass was linked to greater post-operative complications, hospitalization and mortality.

According to the Canadian Cancer Society, in 2020, colorectal cancer is expected to be the second-leading cause of death from cancer in Canadian men and the third-leading cause of death from cancer in women. Surgery is often used to remove the cancer, and post-operative complications can affect a patient's quality of life.

Prado noted that the ability to predict who may suffer poor outcomes after surgery would allow for more personalized treatment and improved patient care.

Patients in the study were assessed using preoperative computerized tomography (CT) scans, a technique that involves taking a series of X-ray images from different angles and using computer technology to create cross-sectional images of the body. Scans are taken during cancer diagnosis, and researchers can also use the images to analyze body composition.

The CT technology is what allows for the added analysis of muscle radiodensity, which is the quality of the muscle itself.

"It's like you're looking at a steak and you have fat inside the steak. Our muscles can be like that too, and that's not good for us--so our study looked at both the mass (the quantity) and also the quality of the muscles, which is the amount of fat infiltration," said Prado.

Prado said colon cancer patients were of particular interest for a variety of reasons. The CT images obtained span the body to the third lumbar vertebrae, a frame that is ideal for assessing body composition. Many patients with colon cancer also commonly fall into the obese weight range, and studying low muscle mass in patients at higher weights can offer added insight.

According to Prado, the knowledge that low muscle quantity and quality are indicative of poor post-operative outcomes can have a major impact on patient care through targeted patient interventions.

"It is possible to preoperatively improve muscle, and through that intervention we can better people's quality of life. So I think exploring ways that we can successfully use this approach is the way of the future," she said.

Boston - Results from a new study led by Boston Medical Center (BMC) demonstrate the disproportionate impact of COVID-19 on Hispanic groups within the US, with the most severe outcomes, including death and intensive care, among Hispanic Black individuals. Analyzing data from the Centers for Disease Control and Prevention, researchers found differences between Hispanic groups, with higher rates of hospitalization and increased risk of death for Hispanic Black compared to Hispanic multiracial individuals. Published online in the Journal of Immigrant and Minority Health, the results highlight that Hispanic populations as a whole have worse COVID-19 outcomes compared to the Hispanic white population, demonstrating the need for more accurate demographic data collection efforts in order to better address the disparities among Hispanic individuals impacted by COVID-19.

Results from previous COVID-19 research have shown that Latinx populations, as a whole, have worse outcomes compared to other ethnic groups. This study, the first to use a nationally representative COVID-19 database, delves further into the data to investigate the differential impact of COVID-19 on different racial groups within the Hispanic community.

For this study, researchers analyzed data reported to the Centers for Disease Control and Prevention between April 5 and May 18, 2020, with a cohort of 78,323 individuals. They compared hospitalization, intensive care unit admission, need for breathing support, and death rates among Hispanic white, Hispanic Black, and Hispanic multiracial/other groups. Next, they compared these results with the data on the above criteria for non-Hispanic white individuals.

Hispanic Black individuals in the cohort had the highest rate of comorbidities, at 51 percent, as well as hospitalizations, which were 45 percent. Hispanic/multiracial individuals were more frequently admitted to the intensive care unit (10 percent), had the highest incidence of requiring breathing support through mechanical ventilation (10 percent) and more frequent rates of death due to COVID-19 (16.1 percent). Overall, Hispanic groups fared worse than non-Hispanic white individuals. The relative risk of death was 1.36, 1.72 and 1.68 times higher for Hispanic white, Hispanic Black and Hispanic multiracial compared to non-Hispanic white individuals.

"Our results clearly show that Hispanic individuals are more likely to be hospitalized and die from COVID-19 infection than non-Hispanic individuals, with the worst outcomes among Hispanic Black individuals," said Sarah Kimball, MD, co-director of BMC's Immigrant & Refugee Health Center and the study's corresponding author. One of the challenges, the authors note, is the incomplete information on race and ethnicity included in the reported data given variations among how the information is collected and reported. At this time, there are no universal standards or processes in place at health care institutions related to how racial or ethnic information is collected from patients.

"The dilemma is that we know these disparities among racial groups aren't biological, and reflect the systemic impacts of racism and inequality. Yet, we need better data collection on racial and ethnic groups, in order to develop interventions tailored to address the COVID-19 disparities among specific patient populations," added Kimball, who is also an assistant professor of medicine at Boston University School of Medicine. "The better data we have access to, the more targeted we can be in our public health and treatment approaches to dismantle the effects of racism and the disparities that we see among different groups within the Hispanic community, which can help decrease COVID-19-specific disparities in these individuals."

Acute liver failure is a devastating, rapidly progressing disease that results in death in 80% of cases, unless an emergency liver transplant is performed. In the developed world, its leading cause is a substantial overdose of acetaminophen, also known as paracetamol.

In a study published in Nature Medicine, researchers from the labs of Profs. Eran Elinav and Ido Amit in the Immunology Department of the Weizmann Institute of Science have, in using mouse models of acute liver failure, discovered three new subsets of liver cells that orchestrate the development of this condition. The scientists also uncovered signals - from the gut microbiome as well as the diseased liver - that jointly activate these cells, and showed that selectively blocking these signals and depleting the microbiome led to marked improvement in liver function and prolonged survival in mice. An analysis of liver tissue from human patients with acute liver failure revealed a molecular pattern strikingly similar to the one identified in mice in the study, raising hopes that the findings in mice may in the future be translated into a treatment for humans.

Dr. Aleksandra Kolodziejczyk, a postdoctoral fellow in Elinav's lab, led this project in collaboration with other scientists at the Weizmann Institute of Science and Dr. Amir Shlomai of the Liver Institute, Rabin Medical Center.

Kolodziejczyk and her colleagues began their exploration by creating gene expression profiles of 45,000 individual mouse liver cells, ultimately generating a comprehensive liver cell atlas in conditions of health and acute liver failure. The scientists identified 49 cell subsets, of which three new subsets - among stellate, endothelial and Kupffer cells - became abnormally activated as the acute liver failure progressed in the mice. These previously undescribed cell subsets secreted a large variety of substances that attracted immune cells from outside the liver, which then contributed to its damage. All three new cell subtypes shared a characteristic expression pattern of 77 genes - a pattern controlled by the same regulatory protein, the transcription factor MYC - which suggested that these cells may be activated through a common program.

The researchers suspected the newly uncovered activation pathway could be regulated by signals from the gut microbiome. This makes anatomical sense, as the gastrointestinal tract drains into the liver though a large network of veins, directly exposing the liver to substances produced in the gut and by its microbes. When the scientists depleted the microbiome of the mice by administering wide-spectrum antibiotics, symptoms of liver failure were alleviated. Moreover, when they induced acute liver failure in germ-free mice, which lack a microbiome, the condition was much less severe than in regular mice. Further studies of mice with and without a gut microbiome revealed that during acute liver failure, distinct molecules generated by the microbiome accumulate in the liver, where they activate the MYC protein in the three liver cell subtypes that contribute to liver damage. In the absence of a microbiome, MYC activation was attenuated, leading to reduced liver damage.

Kolodziejczyk then worked out the molecular details of MYC activation. She found that the molecules coming from the microbiome activate the MYC program through surface receptors on the three cell subtypes that she had identified earlier as aggravating the liver failure. She also found that the MYC program was activated in the same manner - that is, through the same receptors on the three cell subtypes - by signals coming from liver cells damaged by paracetamol.

When the mice were genetically depleted of functioning receptors, given drugs that blocked MYC or otherwise had the signals between these receptors and MYC interrupted, they no longer developed acute liver failure and their survival was extended. Gene expression analysis of individual cells showed that in the treated mice, the three newly identified cell subtypes were no longer abnormally activated, and this reduced both the immune cell infiltration and the resultant liver damage.

Finally, the researchers teamed up with Dr. Shlomai to analyze liver samples from patients with acute liver failure and to compare them with samples from healthy liver donors. Those from the patients - but not from healthy donors - were characterized by robust MYC activation that was similar to the one observed in mice. These results raise the possibility that blocking the MYC program by drugs, coupled with microbiome modulation, may prove to be a potential treatment for acute liver failure.

"Our findings provide a first step towards achieving a comprehensive understanding of how the microbiome interacts with the host in contributing to acute liver failure," Elinav says. "Such knowledge could lead to a new treatment option for this cureless and devastating disorder."

Living organisms aren't the only things that evolve over time. Cultural practices change, too, and in recent years social scientists have taken a keen interest in understanding this cultural evolution. Much research has focused on psychological factors among individuals, like how our visual system constrains the shape of written characters.

But environmental factors like availability of materials or physical space likely play a role, too, says Helena Miton, a Complexity Postdoctoral Fellow at the Santa Fe Institute. Although researchers in the field generally acknowledge the influence of the environment on cultural shifts, she says, the effects have never been investigated experimentally.

To tease out those influences, Miton recently designed a series of experiments -- using three identical drums and over 100 participants -- to investigate the influence of material constraints on the development of culture. She and her collaborators described the experiment and their results in Proceedings of the Royal Society B, the Royal Society's primary biology journal.

The group focused in particular on how environmental factors influence the evolution of rhythm. Miton says she chose to study music because instruments clearly depend on material constraints. The materials available to a community, for example, will determine the kinds of instruments they can create, which in turn shape the acoustics and sounds.

"We wanted to have an experiment that was as simple as possible," says Miton. The researchers recruited 120 participants, none of whom had ever studied music, to participate in an experiment modeled on the game "Telephone." Such so-called transmission chains, says Miton, are often used in laboratory settings to mimic cultural communications.

Participants were divided into chains of six people each. The first person listened to a simple sequence of beats played on three drums, and then attempted to replicate the rhythm. The second person listened to the first person's attempt and tried to replicate it, and so on. Miton and her collaborators studied how the rhythms changed through the transmission.

In some chains, people were given a rhythm to play on drums sitting next to each other. Others had to try to recreate beats on drums separated by larger distances. And still others faced a mix of small and large distances between the drums they were using. In total, the researchers studied four different spatial configurations of drums and compared how the rhythms produced by participants diverged across those configurations.

"People transform what they heard in a very systematic, rather than random, way," says cognitive scientist Dan Sperber at Central European University, in Budapest, who worked with Miton on the project. "We can predict how the rhythms will change." The scientists hypothesized, correctly, that over time the rhythms would diverge significantly from the original seed rhythm, and in a specific way for each configuration.

"This was a proof of concept experiment to show that with different environments, different cultural patterns would emerge," says Miton. "What's important is that we showed that you can parse out ecological and psychological factors."

She says she hopes this simple drum-and-telephone experiment will inspire new ways to tease out the many influences on cultural evolution in the future.

Fossils recovered from Antarctica in the 1980s represent the oldest giant members of an extinct group of birds that patrolled the southern oceans with wingspans of up to 21 feet that would dwarf the 11½-foot wingspan of today's largest bird, the wandering albatross.

Called pelagornithids, the birds filled a niche much like that of today's albatrosses and traveled widely over Earth's oceans for at least 60 million years. Though a much smaller pelagornithid fossil dates from 62 million years ago, one of the newly described fossils -- a 50 million-year-old portion of a bird's foot -- shows that the larger pelagornithids arose just after life rebounded from the mass extinction 65 million years ago, when the relatives of birds, the dinosaurs, went extinct. A second pelagornithid fossil, part of a jaw bone, dates from about 40 million years ago.

"Our fossil discovery, with its estimate of a 5-to-6-meter wingspan -- nearly 20 feet -- shows that birds evolved to a truly gigantic size relatively quickly after the extinction of the dinosaurs and ruled over the oceans for millions of years," said Peter Kloess, a graduate student at the University of California, Berkeley.

The last known pelagornithid is from 2.5 million years ago, a time of changing climate as Earth cooled, and the ice ages began.

Kloess is the lead author of a paper describing the fossil that appears this week in the open access journal Scientific Reports. His co-authors are Ashley Poust of the San Diego Natural History Museum and Thomas Stidham of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing. Both Poust and Stidham received their Ph.Ds from UC Berkeley.

Birds with pseudoteeth

Pelagornithids are known as 'bony-toothed' birds because of the bony projections, or struts, on their jaws that resemble sharp-pointed teeth, though they are not true teeth, like those of humans and other mammals. The bony protrusions were covered by a horny material, keratin, which is like our fingernails. Called pseudoteeth, the struts helped the birds snag squid and fish from the sea as they soared for perhaps weeks at a time over much of Earth's oceans.

Large flying animals have periodically appeared on Earth, starting with the pterosaurs that flapped their leathery wings during the dinosaur era and reached wingspans of 33 feet. The pelagornithids came along to claim the wingspan record in the Cenozoic, after the mass extinction, and lived until about 2.5 million years ago. Around that same time, teratorns, now extinct, ruled the skies.

The birds, related to vultures, "evolved wingspans close to what we see in these bony-toothed birds (pelagornithids)," said Poust. "However, in terms of time, teratorns come in second place with their giant size, having evolved 40 million years after these pelagornithids lived. The extreme, giant size of these extinct birds is unsurpassed in ocean habitats,""

The fossils that the paleontologists describe are among many collected in the mid-1980s from Seymour Island, off the northernmost tip of the Antarctic Peninsula, by teams led by UC Riverside paleontologists. These finds were subsequently moved to the UC Museum of Paleontology at UC Berkeley.

Kloess stumbled across the specimens while poking around the collections as a newly arrived graduate student in 2015. He had obtained his master's degree from Cal State-Fullerton with a thesis on coastal marine birds of the Miocene era, between 17 million and 5 million years ago, that was based on specimens he found in museum collections, including those in the UCMP.

"I love going to collections and just finding treasures there," he said. "Somebody has called me a museum rat, and I take that as a badge of honor. I love scurrying around, finding things that people overlook."

Reviewing the original notes by former UC Riverside student Judd Case, now a professor at Eastern Washington University near Spokane, Kloess realized that the fossil foot bone -- a so-called tarsometatarsus -- came from an older geological formation than originally thought. That meant that the fossil was about 50 million years old instead of 40 million years old. It is the largest specimen known for the entire extinct group of pelagornithids.

The other rediscovered fossil, the middle portion of the lower jaw, has parts of its pseudoteeth preserved; they would have been up to 3 cm (1 inch) tall when the bird was alive. The approximately 12-cm (5-inch-) long preserved section of jaw came from a very large skull that would have been up to 60 cm (2 feet) long. Using measurements of the size and spacing of those teeth and analytical comparisons to other fossils of pelagornithids, the authors are able to show that this fragment came from an individual bird as big, if not bigger, than the largest known skeletons of the bony-toothed bird group.

A warm Antarctica was a bird playground

Fifty million years ago, Antarctica had a much warmer climate during the time known as the Eocene and was not the forbidding, icy continent we know today, Stidham noted. Alongside extinct land mammals, like marsupials and distant relatives of sloths and anteaters, a diversity of Antarctic birds occupied the land, sea and air.

The southern oceans were the playground for early penguin species, as well as extinct relatives of living ducks, ostriches, petrels and other bird groups, many of which lived on the islands of the Antarctic Peninsula. The new research documents that these extinct, predatory, large- and giant-sized bony-toothed birds were part of the Antarctic ecosystem for over 10 million years, flying side-by-side over the heads of swimming penguins.

"In a lifestyle likely similar to living albatrosses, the giant extinct pelagornithids, with their very long-pointed wings, would have flown widely over the ancient open seas, which had yet to be dominated by whales and seals, in search of squid, fish and other seafood to catch with their beaks lined with sharp pseudoteeth," said Stidham. "The big ones are nearly twice the size of albatrosses, and these bony-toothed birds would have been formidable predators that evolved to be at the top of their ecosystem."

Museum collections like those in the UCMP, and the people like Kloess, Poust and Stidham to mine them, are key to reconstructing these ancient habitats.

"Collections are vastly important, so making discoveries like this pelagornithid wouldn't have happened if we didn't have these specimens in the public trust, whether at UC Riverside or now at Berkeley," Kloess said. "The fact that they exist for researchers to look at and study has incredible value."

COMMON MUTATION IN PARKINSON'S DISEASE INCREASES CELL CALCIUM, MAY CAUSE BRAIN CELL DEATH

Media Contact: Rachel Butchrbutch1@jhmi.edu

Johns Hopkins Medicine researchers have mapped out the cellular pathway that connects the most common genetic mutation associated with Parkinson's disease to brain cell death. In a new study, they show that the mutation initiates a biological pathway that could target brain cells most susceptible to the patterns of cell death leading to Parkinson's disease symptoms.

"This deep dive into the molecular players in Parkinson's disease may provide some answers to its onset and progression," says Valina Dawson, Ph.D., professor of neurology at the Johns Hopkins University School of Medicine, and director of both the neuroregeneration and stem cell programs at the medical school's Institute for Cell Engineering.

The study, published Oct. 1, 2020, in the journal Cell Stem Cell, revealed that a mutation in the leucine-rich repeat kinase 2 (LRRK2) gene shifts the balance of protein production within brain cells, allowing calcium to accumulate inside them. Though mutations in LRRK2 are the most common indicators of inherited Parkinson's disease, their functions within cells are not well understood.

Dawson and her research team learned that a specific mutation within the LRRK2 gene, called Gly2019Ser, or G2019S, produces a protein that becomes more active than normal. They found that this increased activity changes how ribosomes, the protein-making factories of the cell, select which RNA molecules are used to make other proteins. Ribosomes affected by the mutated LRRK2 protein prefer some RNAs with more complex structures than other simple RNAs.

"This preference causes major problems down the line, because it may shift the levels of proteins whose precise regulation is essential for neurons to function and survive," explains Dawson.

Among the consequences, says Dawson, is the regulation of many cell structures that are responsible for maintaining healthy levels of calcium. One such affected structure is the voltage-gated calcium ion channel, a portal crucial for processing and sending biochemical messages across the brain. Previous studies established that too much calcium in a brain cell can cause it to die. Excess calcium also has been linked as a contributing factor to Alzheimer's disease.

"Mapping out this progression of events is an important advancement in understanding the disease and provides more information on how Parkinson's disease may initially arise," says Dawson.

The research team hopes its findings provide opportunities to create new therapies for Parkinson's disease. "Defining each step in the pathway linking the LRRK2 mutation and brain cell death represents a potential target for drug interaction," says Dawson.

BETTER REPAIRED NERVE INSULATION MAY LEAD TO NEW MULTIPLE SCLEROSIS TREATMENTS

Media Contact: Vanessa McMains, Ph.D.vmcmain1@jhmi.edu

In a new study using mice, Johns Hopkins Medicine researchers have found a better way than natural healing to repair damaged insulation surrounding nerve cells. Normally, the natural healing process adds bumps to the surface of the protective fatty sheath, known as myelin, each time it's repaired. Over time and after cumulative damage, the myelin ultimately becomes too misshapen to wrap cleanly around the nerve, causing it to lose function.

This happens in multiple sclerosis (MS), a disorder in which the body's immune system mistakenly attacks the myelin around nerves, shutting them down and causing communication problems between the brain and the rest of the body.

In their study published on Oct. 2, 2020, in Science Advances, the researchers say that using certain drugs may prevent relapsing-remitting MS, the intermittent form of the disorder, from becoming progressive MS -- a chronic form of the condition in which the myelin can no longer repair itself.

"Suppressing the immune system has worked to treat relapsing-remitting MS, but it doesn't protect from the eventual advancement to progressive MS, for which there aren't any good treatments on the market," says Norman Haughey, Ph.D., professor of neurology at the Johns Hopkins University School of Medicine. "We think these findings are a big step toward improving the quality and composition of myelin following a flare-up."

In earlier work by Haughey's team, the researchers looked at the composition of the myelin surrounding nerves found near injured brain tissue taken from deceased people with MS. Myelin is made mostly from hundreds of types of fat molecules and proteins. The researchers saw that myelin around nerves near injury sites looked misshapen compared with that of other nerves, along with having much higher levels of ceramide -- a particular type of fat molecule -- and lower levels of another fat molecule called sulfatide.

Having the correct amount of ceramide is especially important because this fat regulates the curvature of myelin -- too much ceramide and it can't wrap tightly around the nerve, creating "bumps" in the myelin.

In the new study, the researchers fed the drug cuprizone to mice for 26 days to damage the myelin on their nerve cells. The myelin repaired itself, but looked it bumpy and wrapped poorly around the nerve because of the excess ceramide. In a series of experiments, the researchers found that brain inflammation activates the enzyme, neutral sphingomyelinase-2, which produces ceramide.

Working with an expert drug development team led by Barbara Slusher, Ph.D., M.A.S., professor of neurology at the Johns Hopkins University School of Medicine, the researchers identified the small molecular size drug, cambinol, which blocks neutral sphingomyelinase-2 from working. They theorized that this would prevent excess ceramide from being made and incorporated into regenerated myelin after an injury.

After nearly a month of feeding their mice cuprizone to cause myelin damage, the researchers injected them with cambinol. When the myelin grew back this time, it wrapped tightly around the neurons and looked like it did before the damage.

The researchers say this intervention did not completely restore the fat composition of myelin, but it appeared to increase the stability of the myelin, which likely would better protect the underlying neurons.

The team needs to determine if there are impacts from other abnormal fat levels in the repaired myelin even with the prevention of excess ceramide buildup. Also, the researchers need to confirm that the myelin -- after being in its correct shape and structure -- functions as it should and is more stable over long periods of time.

Once this is done, the team hopes to develop small molecular-size inhibitors of neutral sphingomyelinase-2 for eventual use in human trials.

Postdoctoral fellow Seung-Wan Yoo, Ph.D., M.S., is the lead author of this study.

Scientists at Fred Hutchinson Cancer Research Center in Seattle have shown that a potent antibody from a COVID-19 survivor interferes with a key feature on the surface of the coronavirus's distinctive spikes and induces critical pieces of those spikes to break off in the process.

The antibody -- a tiny, Y-shaped protein that is one of the body's premier weapons against pathogens including viruses -- was isolated by the Fred Hutch team from a blood sample received from a Washington state patient in the early days of the pandemic.

The team led by Drs. Leo Stamatatos, Andrew McGuire and Marie Pancera previously reported that, among dozens of different antibodies generated naturally by the patient, this one -- dubbed CV30 -- was 530 times more potent than any of its competitors.

Using tools derived from high-energy physics, Hutch structural biologist Pancera and her postdoctoral fellow Dr. Nicholas Hurlburt have now mapped the molecular structure of CV30. They and their colleagues published their results online today in the journal Nature Communications.

The product of their research is a set of computer-generated 3D images that look to the untrained eye as an unruly mass of noodles. But to scientists they show the precise shapes of proteins comprising critical surface structures of antibodies, the coronavirus spike and the spike's binding site on human cells. The models depict how these structures can fit together like pieces of a 3D puzzle.

"Our study shows that this antibody neutralizes the virus with two mechanisms. One is that it overlaps the virus's target site on human cells, the other is that it induces shedding or dissociation of part of the spike from the rest," Pancera said.

On the surface of the complex structure of the antibody is a spot on the tips of each of its floppy, Y-shaped arms. This infinitesimally small patch of molecules can neatly stretch across a spot on the coronavirus spike, a site that otherwise works like a grappling hook to grab onto a docking site on human cells.

The target for those hooks is the ACE2 receptor, a protein found on the surfaces of cells that line human lung tissues and blood vessels. But if CV30 antibodies cover those hooks, the coronavirus cannot dock easily with the ACE2 receptor. Its ability to infect cells is blunted.

This very effective antibody not only jams the business end of the coronavirus spike, it apparently causes a section of that spike, known as S1, to shear off. Hutch researcher McGuire and his laboratory team performed an experiment showing that, in the presence of this antibody, there is reduction of antibody binding over time, suggesting the S1 section was shed from the spike surface.

The S1 protein plays a crucial role in helping the coronavirus to enter cells. Research indicates that after the spike makes initial contact with the ACE2 receptor, the S1 protein swings like a gate to help the virus fuse with the captured cell surface and slip inside. Once within a cell, the virus hijacks components of its gene and protein-making machinery to make multiple copies of itself that are ultimately released to infect other target cells.

The incredibly small size of antibodies is difficult to comprehend. These proteins are so small they would appear to swarm like mosquitos around a virus whose structure can only be seen using the most powerful of microscopes. The tiny molecular features Pancera's team focused on the tips of the antibody protein are measured in nanometers -- billionths of a meter.

Yet structural biologists equipped with the right tools can now build accurate 3D images of these proteins, deduce how parts of these structures fit like puzzle pieces, and even animate their interactions.

Fred Hutch structural biologists developed 3D images of an antibody fished from the blood of an early COVID-19 survivor that efficiently neutralized the coronavirus.

Dr. Nicholas Hurlburt, who helped develop the images, narrates this short video showing how that antibody interacts with the notorious spikes of the coronavirus, blocking their ability to bind to a receptor on human cells that otherwise presents a doorway to infection.

Key to building models of these nanoscale proteins is the use of X-ray crystallography. Structural biologists determine the shapes of proteins by illuminating frozen, crystalized samples of these molecules with extremely powerful X-rays. The most powerful X-rays come from a gigantic instrument known as a synchrotron light source. Born from atom-smashing experiments dating back to the 1930s, a synchrotron is a ring of massively powerful magnets that are used to accelerate a stream of electrons around a circular track at close to the speed of light. Synchrotrons are so costly that only governments can build and operate them. There are only 40 of them in the world.

Pancera's work used the Advanced Photon Source, a synchrotron at Argonne National Laboratory near Chicago, which is run by the University of Chicago and the U.S. Department of Energy. Argonne's ring is 1,200 feet in diameter and sits on an 80-acre site.

As the electrons whiz around the synchrotron ring, they give off enormously powerful X-rays -- far brighter than the sun but delivered in flashes of beams smaller than a pinpoint.

Structural biologists from around the world rely on these brilliant X-ray beamlines to illuminate frozen crystals of proteins. They reveal their structure in the way these bright beams are bent as they pass though the molecules. It takes powerful computers to translate the data readout from these synchrotron experiments into the images of proteins that are eventually completed by structural biologists.

The Fred Hutch team's work on CV30 builds on that of other structural biologists who are studying a growing family of potent neutralizing antibodies against the coronavirus. The goal of most coronavirus vaccine candidates is to stimulate and train the immune system to make similar neutralizing antibodies, which can recognize the virus as an invader and stop COVID-19 infections before they can take hold.

Neutralizing antibodies from the blood of recovered COVID-19 patients may also be infused into infected patients -- an experimental approach known as convalescent plasma therapy. The donated plasma contains a wide variety of different antibodies of varying potency. Although once thought promising, recent studies have cast doubt on its effectiveness.

However, pharmaceutical companies are experimenting with combinations of potent neutralizing antibodies that can be grown in a laboratory. These "monoclonal antibody cocktails" can be produced at industrial scale for delivery by infusion to infected patients or given as prophylactic drugs to prevent infection. After coming down with COVID-19, President Trump received an experimental monoclonal antibody drug being tested in clinical trials by the biotech company Regeneron, and he attributes his apparently quick recovery to the advanced medical treatment he received.

The Fred Hutch research team holds out hope that the protein they discovered, CV30, may prove to be useful in the prevention or treatment of COVID-19. To find out, this antibody, along with other candidate proteins their team is studying, need to be tested preclinically and then in human trials.

"It is too early to tell how good they might be," Pancera said.

In the world of rare genetic diseases, exome and genome sequencing are two powerful tools used to make a diagnosis. A recent addition to the toolkit, RNA sequencing, has been demonstrated to help researchers narrow down disease candidate variants identified first on exome and genome sequencing. A new study from Baylor College of Medicine finds that starting genetic analysis with RNA sequencing can increase diagnostic yield even further. The results are published in the Journal of Clinical Investigation.

Baylor has been a leader in developing clinical applications of exome and genome sequencing, a technique that is now being used in clinics worldwide. Researchers at the National Institutes of Health (NIH) Undiagnosed Diseases Network (UDN) have successfully used exome and genome sequencing to increase the diagnostic rate of rare genetic diseases to about 35%.

"That's impressive because these cases have already had such an extensive workup already," said Dr. Brendan Lee, corresponding author on the study and professor and chair of molecular and human genetics at Baylor. "The 35% diagnostic rate is great, but unfortunately that means there's still 65% that remain undiagnosed."

Exome and genome sequencing do have limits. Over the years, scientists have identified about 4,000 disease-causing genes and 7,000 associated distinct clinical diseases, but relatively little is known about the roughly 16,000 other genes in the genome. Further, only about 1 or 2% of the genome is coding, meaning it is translated into RNA and proteins. Researchers are limited in their ability to interpret genetic changes in the noncoding regions of the genome.

"When a patient's exome and genome is sequenced, we interpret the results and come up with a list of gene mutations that could cause a disease," said Lee, the Robert and Janice McNair Endowed Chair in Molecular and Human Genetics at Baylor. "Often, we can't assign a definitive effect to many DNA mutations because there's not enough information."

To assist in interpretation of exome and genome sequencing, the UDN has increasingly turned to RNA sequencing. While exome and genome sequencing identify genetic changes in the DNA, RNA sequencing can reveal the effects of those changes, for example if a gene has lower expression than expected. RNA sequencing can also tell us about the effects of noncoding changes, something that is very important as we transition from exome to genome sequencing.

Trying a new approach

RNA sequencing has been used as a secondary tool to help prioritize disease gene candidates identified with exome and genome sequencing, and it has been shown to increase diagnostic yield to variable degrees. The Baylor team wanted to try a different approach with the UDN cases. Using a novel pipeline developed with collaborators in Germany, they started with the RNA sequencing to first identify unique differences in gene expression and splicing. Researchers could then trace the problem back to a corresponding genetic change in the exome and genome sequencing data.

"This strategy really flips the way we normally approach a case, looking at the end result in the RNA and working backwards to find the cause in the exome or genome. It allows biology to tell us where to look to make a diagnosis," said Dr. David Murdock, lead author of the study and assistant professor of molecular and human genetics at Baylor.

"We found this RNA sequencing first approach was extremely powerful," Lee said. "It was able to very rapidly point at the gene we should look at. Moreover, it did so in cases in which we would not have been able to identify the disease gene candidate using exome and genome sequencing alone. If we had used the old way and generated a priority candidate list, these gene mutations would not have even been in the priority list."

Increased diagnostic yield

The team found that exome and genome sequencing sometimes missed small deletions in genes. However, the RNA sequencing data showed that these deletions could dramatically affect gene expression. RNA sequencing also picked up changes in expression and splicing caused by variants in noncoding regions that would not have been flagged in regular exome and genome sequencing.

"We see lots of changes in the noncoding region, and there's no way to know if they're important," Lee said. "But the RNA sequencing will show an 80% decrease in expression related to that gene, and then we can assign causality to that noncoding variant."

The Baylor study found that beginning with RNA sequencing could increase the diagnostic yield 17% from the traditional exome and genome sequencing approach, bringing their overall diagnosis rate to roughly 50%. As part of the study, researchers analyzed both skin cells and blood cells and found that skin cells were more informative in diagnosis because of their homogenous nature and better gene expression.

"I see RNA sequencing with this approach as eventually becoming standard practice, especially as we move more from exome to genome sequencing. It allows us to diagnose so many more patients and gives families the answer they've been seeking," Murdock said.

"A diagnosis is not black and white. It involves variable amounts of certainty," Lee said. "The availability of this tool will change the certainty level, improving diagnostic yield and increasing confidence in that diagnosis."

Genetic factors that reduce the placenta's capacity to protect the fetus from the zika virus are described by Brazilian researchers in an article published in PLOS Neglected Tropical Diseases. According to the authors, the findings help explain why only some babies whose mothers are infected by zika virus during pregnancy are born with some kind of anomaly.

Since the 2015 epidemic at least 3,500 babies have suffered from zika congenital syndrome, which includes microcephaly, brain calcifications, and auditory and visual deficits, according to statistics available from the Brazilian Health Ministry. However, these cases are believed to correspond to between 5% and 10% of all the fetuses exposed to zika in the first trimester, the riskiest period of pregnancy.

"We observed differences in the expression of two classes of genes in the placenta of the affected babies. One is associated with the placenta's capacity to invade and attach to the wall of the uterus. The other has to do with the production of certain molecules known as chemokines, which attract maternal immune cells to combat the virus in the placental barrier," said Sergio Verjovski , a professor in the University of São Paulo's Chemistry Institute (IQ-USP) and principal investigator for the study, which was supported by São Paulo Research Foundation - FAPESP .

The discovery was only possible thanks to a cellular reprogramming technique that enabled the researchers to recreate in the laboratory the cells that make up the so-called primitive placenta, which gives the fetus support in the first trimester.

These cells, called trophoblasts, were obtained from blood samples donated by three pairs of discordant twins - cases in which only one sibling was born with microcephaly although both were equally exposed to viral infection in the womb.

Because these children represent an ideal model for the study of genetic factors that increase susceptibility to congenital zika syndrome, they have been monitored for about four years by researchers affiliated with the Human Genome and Stem-Cell Research Center (HUG-CELL), one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP. HUG-CELL's principal investigator is Mayana Zatz , a professor in the University of São Paulo's Bio-Science Institute (IB-USP) and a co-author of the article.

"First we reprogrammed the blood cells so that they returned to a stage of pluripotency similar to that of embryo stem cells," Verjovski said. "Then we had these induced pluripotent stem cells [IPSCs] differentiate in vitro into primitive trophoblasts."

Next, two groups of placental cells were cultured, one to simulate the primitive placenta of babies born with microcephaly and hence most affected by zika, and the other to represent the placenta of twins resistant to viral infection.

All the cultured cells were infected with a Brazilian strain of the virus (ZIKV-BR), which circulated here during the 2015-16 epidemic. The researchers then used sequencing techniques to compare the two groups' transcriptomes (all RNA molecules expressed by their genes). The aim was to see in each case how the virus affected gene expression in placental cells.

"In the trophoblasts of the babies born with microcephaly, we observed decreased expression of several genes associated with the extracellular matrix. These genes are a key part of a process whereby the placenta, which is fetal tissue, invades and attaches to the uterus," Verjovski said. "This process is important for the placenta to nourish the fetus properly and act as a physical barrier against pathogens and toxins."

Analysis conducted 48 and 96 hours after infection showed statistically significant growth of chemokines RANTES/CCL5 (up to 4.6 times) and IP10 (up to 96 times) only in the trophoblasts from the resistant babies.

"These molecules are important signalers to the mother's immune defense in the placental barrier. They attract to the site maternal cells capable of destroying the virus," Verjovski said.

The results, therefore, suggest that the primitive placenta in resistant babies is able to prevent infection of fetal tissue more effectively.

"We would need to perform new experiments to confirm this hypothesis," Verjovski said. "One possibility would be placing the trophoblasts infected with zika in contact with blood samples from pregnant women, and observing whether placental cells of resistant babies are indeed able to attract more of the mother's immune cells. However, this isn't easy to do: we would need to obtain blood samples from pregnant women whose immune cells were compatible with the discordant twins' cells."

In any event, he continued, the identification of genes differentially expressed in babies with microcephaly paves the way for research that aims to develop interventions capable of preventing damage to the fetus by the virus. "We think it would be more feasible to develop a treatment that reinforces the placental barrier and prevents infection of the fetus than to invest, for example, in a drug that blocks damage by the virus directly in the fetal nervous system," he said.

More than genetics

In a study published in 2017 in PNAS, Verjovski and collaborators at the University of Missouri in the United States showed that the primitive placenta offers a far more favorable environment to infection by zika than the mature placenta because of increased first-trimester expression of several genes that encode attachment proteins that facilitate viral entry into fetal tissue. On the other hand, the mature placenta expresses more proteins associated with antiviral defense. This study involved primitive and mature trophoblasts also obtained by cellular reprogramming, but from embryonic stem cells (and hence not from children exposed to the virus during pregnancy).

"At the time we raised the hypothesis that the primitive placenta in fetuses susceptible to zika expressed more attachment receptors so that these babies were exposed to a higher viral load. We've now refuted this theory with the new findings," Verjovski said.

The latest study showed, he added, that gene expression is initially the same in trophoblasts from twins born with and without microcephaly, but becomes different after viral infection. "For some unknown reason, the placenta responds differently to viral cell entry in susceptible and resistant babies," he said.

Other genetic factors associated with greater susceptibility to zika congenital syndrome were described by the HUG-CELL team in an article published in 2018 in Nature Communications . The researchers showed that zika replicated much more in neural progenitor cells (NPCs) from babies with microcephaly than in NPCs from their resistant siblings. Furthermore, NPCs from susceptible babies proliferated less and died more than NPCs from resistant babies. In this case, the NPCs were also generated by cellular reprogramming from blood samples donated by discordant twins.

A comparison of gene expression in the two groups brought to light differences in two important signaling pathways for brain development during the embryonic period - one mediated by the protein mTOR and the other by Wnt. These pathways regulate the proliferation and migration of central nervous system cells, among other things (read more at: agencia.fapesp.br/27084).

Other factors that have been associated with a heightened risk of fetal anomalies besides genetics include maternal diet, gut microbiota composition, and maternal exposure to pollutants and other pathogens. One of the questions that remain open is why in some regions, such as the Northeast of Brazil, zika caused many more cases of microcephaly than in others where zika outbreaks also occurred.

"In the study published in 2017, we compared two different zika strains - one isolated in Uganda [in Africa, where the virus originated] and another in Polynesia. The Brazilian strain derived from the latter," Verjovski said. "We found the African strain to be far more virulent in the primitive placenta. It's possible therefore that no cases of microcephaly occurred in Africa because the pregnant women infected there miscarried and the virus became less destructive as it mutated so that it was able to replicate for longer in the fetus and a larger number of infected women were able to take their pregnancies to term."