Tuesday, January 12, 2021

San Diego Zoo gorillas contract COVID, raising alarms for great apes in wild

A mountain gorilla mother and her baby in the wild in Rwanda. Great apes "are important not just to ecosystems but to giving us insights into understanding our own selves and our evolutionary past," says Emory disease ecologist Thomas Gillespie.

By Carol Clark

The news that some members of the gorilla troop at the San Diego Zoo have tested positive for the virus that causes COVID-19 ramps up the urgency for protecting great apes in the wild from exposure, warns Thomas Gillespie, an Emory disease ecologist. 

“This first known transmission to apes confirms what we strongly suspected — that one of our closest living relatives is susceptible to the novel coronavirus,” says Gillespie, an associate professor in Emory’s Department of Environmental Sciences and Rollins School of Public Health. “More than ever, it’s a race against time. If gorillas in the wild become infected it will be a much more dangerous scenario because we won’t have the ability to contain it.” 

In March, Gillespie co-authored a Nature commentary warning that non-human great apes are susceptible to human respiratory diseases and that COVID-19 could prove devastating to animals on the brink of extinction. 

The non-human great apes include chimpanzees, bonobos and gorillas, which live in equatorial Africa, and orangutans, which are native to the rainforests of Indonesia and Malaysia. The International Union for Conservation of Nature (IUCN) lists chimpanzees and bonobos as endangered species, while gorillas and orangutans are critically endangered. 

Even exposure to viruses that have mild effects in people, such as those causing the common cold, have been associated with mortality events in wild primates. 

The San Diego Zoo Safari Park reported that it conducted tests for the presence of the SARS-CoV-2, the coronavirus that causes COVID-19, after two of its gorillas began coughing. On January 11, the test results confirmed the presence of the virus in some of its gorillas, the zoo announced in a release, adding that it suspects that the virus was transmitted by an asymptomatic staff member, despite the strict prevention protocols in place. 

Great apes, in particular, are at risk from many human diseases due to our close relationship. Chimpanzees and bonobos are our nearest living relatives, sharing about 99 percent of human DNA, while gorillas are our next closest relatives, sharing 98 percent of our DNA. 

The great apes also share key sites within the ACE2 receptor protein with humans that allow SARS-CoV-2 to bind onto cells and infect them. 

Gillespie is a member of an IUCN task force focused on mitigating the impact of COVID on great apes and other primates. He is working with governments and organizations in Africa, including the Jane Goodall Institute, to provide scientifically-informed guidance on protecting wild apes during the pandemic as tourism, research and other activities that lead to human-ape overlap resume. The IUCN Save Our Species Program provided funding to support communities impacted by the loss of great ape tourism, to help prevent people from resorting to poaching animals or logging their habitats. Some of those funds are set to run out soon. 

Gillespie’s lab is also developing a spatially-explicit model to investigate key factors that may affect the spread of the virus among wild primates, so that governments and organizations can prioritize efforts to protect the animals. 

“What’s happened in San Diego has brought the pandemic risks for great apes back into the spotlight,” Gillespie says. “Great apes are our closest relatives and many of them are critically endangered, on the verge of extinction. We’ve gained a lot of insights into our own health and biology by studying these animals. They are important not just to ecosystems but to giving us insights into understanding our own selves and our evolutionary past.”

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Monday, January 11, 2021

Movers and shakers: New evidence for a unifying theory of granular physics

Understanding the dynamics of granular materials — such as sand flowing through an hourglass or salt pouring through a shaker — is a major unsolved problem in physics. A new paper describes a pattern for how record-sized events affect the dynamics of a shaken granular material as it moves from an excited to a relaxed state, adding to the evidence that a unifying theory underlies this behavior. 

The Proceedings of the National Academy of Sciences (PNAS) published the work by Stefan Boettcher, an Emory theoretical physicist, and Paula Gago, an expert in modeling the statistical mechanics of granular matter in the Department of Earth Science and Engineering at the Imperial College of London. 

“Our work marks another small step forward to describing the behavior of granular materials in a uniform way,” says Boettcher, professor and chair of Emory’s Department of Physics. “A complete understanding of granular materials could have a huge impact on a range of industries,” he adds. 

“To name just a few examples, it’s relevant to the compaction of granules into pellets to make pills, the processing of grains in agriculture and to predict behaviors of all kinds of geophysical matter involved in civil engineering.”


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Friday, January 8, 2021

Chemists invent shape-shifting nanomaterial with biomedical potential

Electron micrographs give a detailed view of the new nanomaterial. Arrows indicate layers that form in the tubes, leading to the hypothesis that the sheets form tubes by scrolling in at the corners.

Chemists have developed a nanomaterial that they can trigger to shape shift — from flat sheets to tubes and back to sheets again — in a controllable fashion. The Journal of the American Chemical Society published a description of the nanomaterial, which was developed at Emory University and holds potential for a range of biomedical applications, from controlled-release drug delivery to tissue engineering. 

The nanomaterial, which in sheet form is 10,000 times thinner than the width of a human hair, is made of synthetic collagen. Naturally occurring collagen is the most abundant protein in humans, making the new material intrinsically biocompatible. 

“No one has previously made collagen with the shape-shifting properties of our nanomaterial,” says Vincent Conticello, senior author of the finding and Emory professor of biomolecular chemistry. “We can convert it from sheets to tubes and back simply by varying the pH, or acid concentration, in its environment.” 

The Emory Office of Technology Transfer has applied for a provisional patent for the nanomaterial.


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Wednesday, December 16, 2020

Whole genomes map pathways of chimpanzee and bonobo divergence

A bonobo in the wild. "Understanding the physiological mechanisms underlying the differences in chimpanzee and bonobo behaviors may also give us information about the genes underlying our own behaviors," says Emory anthropologist John Lindo. (Photo by Sarah Kovalaskas)

By Carol Clark

Chimpanzees and bonobos are sister species that diverged around 1.8 million years ago as the Congo River formed a geographic boundary and they evolved in separate environments. Now, a whole-genome comparison of bonobos and chimpanzees reveals the gene pathways associated with the striking differences between the two species’ diets, sociality and sexual behaviors. 

The journal Genes, Brain and Behavior published the comparative analysis, conducted by anthropologists at Emory University.

 

“Our paper is the first whole-genome positive selection scan between chimpanzees and bonobos,” says John Lindo, Emory assistant professor of anthropology and senior author of the study. “We contrasted the genomes of both species to understand how natural selection has shaped differences between the two closely related primates.”  

 

Lindo is a geneticist specialized in ancient DNA and natural selection. “Chimpanzees and bonobos are fascinating because they are very, very closely linked genetically but they have huge behavioral differences,” he says.

 

The two species also share around 99 percent of human DNA, making them our closest living relatives in the animal kingdom. “Understanding the physiological mechanisms underlying the differences in chimpanzee and bonobo behaviors — particularly the much stronger propensity of bonobos toward conflict resolution instead of fighting — may also give us information about the genes underlying our own behaviors,” Lindo says.

 

Sarah Kovalaskas, an Emory graduate student of anthropology, is first author of the paper. Before joining Emory she spent nine months in the field, studying the social development of juvenile bonobos in the Democratic Republic of Congo (DRC). Wild bonobos, an endangered species, are only found in forests south of the Congo River in the DRC.

 

“Bonobos are well-known for being playful, even as adults,” Kovalaskas says. “It was fun to observe the juveniles twirling around in the trees, chasing one another and trying to pull each other down. When the mothers tried to wean them, they would sometimes throw tantrums and scream and run around. You can’t help but recognize the similarity in behaviors to humans.” 


Emory graduate student Sarah Kovalaskas in the field in the Democratic Republic of the Congo.
 

Populations of chimpanzees, also an endangered species, are found in a forested belt north of the Congo River and scattered in a few other areas of west and central Africa. 

 

Bonobos and chimpanzees closely resemble one another physically and they were not recognized as separate species until the 1930s. Their behavioral differences are much more distinct. While bonobos organize into female-led societies, chimpanzees are patriarchal. When bonobos encounter other bonobo groups they generally interact peacefully. Bonobos are also known for using sexual behaviors to defuse tension — including same-sex behaviors among females. Chimpanzees, however, tend to act more aggressively when encountering other chimpanzee groups and may even have violent exchanges that include fatalities. 

 

A leading hypothesis suggests that different feeding ecologies were key to the behavioral divergence between the two species. This theory posits that the abundant ground vegetation in the bonobo territory provided easy access to year-round food without competition from other individuals. Larger groups could feed together instead of foraging in isolation, allowing females to develop strong bonds to counter male domination, and to mate with less aggressive males, leading to a kind of “self-domestication.”

 

The whole genome comparison showed selection in bonobos for genes related to the production of pancreatic amylase — an enzyme that breaks down starch. Previous research has shown that human populations that began consuming more grains with the rise of agriculture show an increase in copies of a closely related gene that codes for amylase.

 

“Our results add to the evidence that diet and the available resources had a definite impact on bonobo evolution,” Kovalaskas says. “We can see it in the genome.”

 

Compared to chimpanzees, bonobos also showed differences in genetic pathways well-known to be related to social behaviors of animals — as well as humans. Bonobos had strong selection for genes in the oxytocin receptor pathway, which plays a role in promoting social bonds; serotonin, involved in modulating aggression; and gonadotropin, known to affect sexual behavior.

 

“The strong female bonds among bonobos, in part, may be mediated by their same-sex sexual behaviors,” says co-author James Rilling, professor and chair of Emory’s Department of Anthropology. “Our data suggest that something interesting is going on in the bonobo pathways for oxytocin, serotonin and gonadotropin and that future research into the physiological mechanisms underlying behavioral differences between bonobos and chimpanzees may want to target those specific systems.”


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Thursday, December 10, 2020

First-known iguana burrow fossil discovered

An illustration of how the trace fossil of the iguana burrow (shown in cross-section) and the surrounding landscape may have looked during the Late Pleistocene Epoch. (Illustration by Anthony Martin)

The discovery of the first known fossil iguana nesting burrow, on an outer island of the Bahamas, fills in a gap of scientific knowledge for a prehistoric behavior of an iconic lizard. PLOS ONE published the finding by scientists from Emory University, which also uncovers new clues to the geologic and natural history of the Bahamas. 

The fossilized burrow dates back to the Late Pleistocene Epoch, about 115,000 years ago, and is located on the island of San Salvador — best known as the likely spot where Christopher Columbus made his first landfall in his 1492 voyage. 

“San Salvador is one of the outer-most islands in the Bahamas chain and really isolated,” says Anthony Martin, a professor in Emory’s Department of Environmental Sciences and senior author of the PLOS ONE paper. “It’s a mystery how and when the modern-day San Salvadoran rock iguanas arrived there. Today, they are among the rarest lizards in the world, with only a few hundred of them left.”

Martin’s specialty is ichnology — the study of traces of life, such as tracks, nests and burrows. He documents modern-day traces to help him identify trace fossils from the deep past to learn about prehistoric animal behaviors. 


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