Friday, April 21, 2017

Better pollen barcoding breaking down barriers to plant identification

"We're interested in pulling pollen off of bees, sequencing that pollen, and figuring out what the bees have been eating," says Emory biologist Berry Brosi. "We can start to construct networks between plants and pollinator species."

By Carol Clark

Pollen goes back about 491.2 million years, to the Devonian Period. Analysis of its traces have long been used to help solve mysteries related to the history of plants on Earth — from dating rocks for oil exploration to understanding the cultural practices of ancient peoples and investigating past habitats.

Now pollen analysis is poised to play an increasing role in solving modern-day mysteries, aided by gene-sequence libraries and advances in DNA barcoding, or the use of DNA to identify species. DNA metabarcoding enables the analysis of multi-species samples, if those species are contained in a gene-sequence reference library.

The Berry Brosi lab in Emory’s Department of Environmental Sciences recently expanded this gene-sequence library, adding a database for the rbcL gene to the already developed ITS2-gene library to improve the accuracy of plant species identification.

“We’re interested in pulling pollen off of bees, sequencing that pollen, and figuring out what the bees have been eating,” says Brosi, whose lab studies both managed honeybees and wild bees. “We can start to construct networks between plants and pollinator species.”

While Brosi is focused on bee research, pollen analysis contains temporal and spatial signatures that have the long-range potential for a broad range of applications, including forensic investigations. Examples include pinpointing the origin of an illicit drug, testing whether the marketing labels on products such as honey and olive oil match their actual geographic provenance, and determining whether the body of a murder victim had been moved.

The journal Applications in Plant Sciences published the work on the new rbcL library, and the database is publicly available.

“We chose rcbL because the length of the gene is readily applied to modern high-throughput sequencing methods,” says Karen Bell, who led the work as an Emory post-doctoral fellow.

The new rbcL library contains sequences from more than 38,400 plant species, adding to the ITS2 library of sequences from more than 72,000 species. After combining the two markers, the Brosi lab demonstrated that it could identify eight of nine plant species in a mixture, compared to only six species-level identifications based on ITS2 alone.

“Now you can simultaneously run a single analysis for both markers on the same sample,” Brosi says. “It’s a streamlined process that reduces false positives and false negatives coming back from the bioinformatics pipeline.”

If a plant species is not included in the reference library, however, it cannot be identified by DNA barcoding, so more sequences from the estimated 450,000 species of flowering plants must be added to make the pollen databases more comprehensive.

The Brosi lab tweaked the DNA metabarcoding bioinformatics pipeline to make it capable of using additional DNA barcodes once their databases have been developed. “The more genetic markers available,” Bell says, “the greater the chance of genetic identification.”

As the cost of genome sequencing comes down, researchers won’t be restricted to scanning the barcodes of small fragments of DNA either: “At some point in the future,” Bell says, “we’ll be doing DNA barcoding using whole plant genomes. The laboratory technology is available, but currently we don’t have enough complete plant genomes to make the databases.”

Another problem that the Brosi lab is working on is the fact that pollen samples are almost always mixed, and the current analytical methods are not quantitative. “We don’t know what the proportion of any species of pollen is within a sample,” Brosi says. “We’re currently trying to disentangle that problem.”

The Botanical Society of America contributed to this report. 

Related:
Pistil-packing science: Pollen genetics could help fight crime
Top 10 polices needed now to protect pollinators

Wednesday, April 19, 2017

For Emory students, 'a lifestyle approach to health'

First-year student Jessie Brightman participates in a class discussion in Health 200. Emory's peer-taught Health 1,2, 3 Program opens avenues for students to have stewardship of their own health. Emory Photo/Video

By April Hunt
Emory Report

If you’re going to change the way that college students talk about health, the first step is for students to do the talking.

It didn’t take long for Michelle Lampl to realize that. As director of Emory’s Center for the Study of Human Health, Lampl saw the success in a pilot “health partner” initiative conducted at the Center for Health Discovery and Well-Being, and turned it into the Human Health 1,2,3 Program for Emory College undergraduates.

The peer-taught program draws on the principles of predictive health and opens avenues for students to have stewardship of their own health. And, because Health 100 is required for every first-year Emory College student, the success of that foundational course has helped bolster student understanding of health.

“Emory is a leader in the paradigm shift in the science of health,” Lampl says. “Medicine is defined by disease. We focus on health. Our program is about changing the culture.”

Launched in 2012, human health is an interdisciplinary degree that has exploded in demand, from four majors its first year to 250 now. It has also attracted the notice of peer schools and beyond for its innovative approach that connects the liberal arts focus of Emory College with the groundbreaking research in public and global health sciences happening across the university.

Health 1,2,3 offers undergraduates the sort of education often reserved for graduate students: a framework to understand not only the science needed in health-related careers, but also the physical, mental and spiritual components of health.

Here’s how it works: All first-year students must take Health 100, which includes the study of timely health topics, such as getting enough sleep, and training for each student to set specific goals. 

Students who find Health 100 informative can enroll in Health 200, where they get training on the science of health and how to lead peers in discussions. Health 300 is the course where trained students become peer health partners for Health 100, overseeing the course with faculty supervision. 

“The way I describe it is, this is a lifestyle approach to health,” says Dylan Hurley, a first-year student who enrolled in Health 200 this spring.

“This is an integration of science and discussion, to make the concepts come to life,” Hurley adds. “That’s what makes it so essential.”

Read the whole article in Emory Report.

Related:
Human health major aims at culture change
New health course shifts to peer-led, personalized approach

Thursday, April 13, 2017

The Peeps experiments: Science that never goes stale


It’s that time of year again: The sugary, squishy, neon-bright baby chicks and bunnies known as Peeps have reappeared and people are inexplicably eating them. Vox wrote a roundup of some of the best cultural phenomena concerning Peeps over the years. It included an excerpt from a classic Emory Report story from 1999, describing how Emory researchers Gary Falcon and James Zimring “performed perhaps the most exhaustive Peeps testing in human history," exploring the candies’ durability in the face of a variety of substances:

“To test Peep solubility, they began with simple tap water, then moved on to boiling water, then to acetone, sulfuric acid and sodium hydroxide, but were left dumbfounded by Peeps' apparent invulnerability to each.

“Then they tried Phenol, a protein-dissolving solvent lethal to humans in amounts as small as a single gram. Peeps proved mortal to such a substance — well, almost. One hour after plunging an unfortunate Peep into its grisly demise, all that remained in the beaker was a pair of brown carnauba wax eyes floating in a purple Phenol soup.”

Emory’s groundbreaking Peeps research lives on at peepresearch.org, including details of an investigation of the effects of smoking and alcohol on Peeps health and the medical miracle of separating quintuplet Peep siblings, conjoined at birth.

Monday, April 10, 2017

Small world, big impact: The Emory Global Health Institute

The Emory Global Health Institute helped fund a program in Haiti for those suffering from depression in communities ravaged by natural disaster and conflict. This photo, near the town of Hinche, was taken by Emory medical student Jesse Rappaport, one of the 2016 winners of the EGHI Global Health Student Photography Contest.

By Sylvia Wrobel
Emory Magazine 

The little boy died at home, without medical attention, before his fifth birthday. It happens to as many as one in five children in poor African and South Asian countries. The boy was deeply mourned, but never counted. His death was not noted in any registry. Except for a fever, no one had any idea why he died—information that might have been lifesaving for family members, or helped health officials recognize and address a widespread problem, or been the earliest indication of a smoldering epidemic.

In 2015, when the Bill and Melinda Gates Foundation wanted to learn why so many die young, they turned to the Emory Global Health Institute (EGHI) to lead the Child Health and Mortality Prevention and Surveillance Network (CHAMPS), designed to help high-child-mortality countries strengthen their capability to collect, analyze, interpret, and share data. Innovative methods include training local teams to visit families soon after a child dies,gathering information on symptoms and, with permission, taking small needle tissue biopsies, which when examined with specialized tools developed at the US Centers for Disease Control and Prevention (CDC) can identify the specific organisms causing illness and death.

“While we would think we have a pretty good idea of why children are dying—respiratory disease, enteric infections, fevers, and sepsis from different microorganisms—we don’t know those specific causes,” says Jeffrey Koplan, former director of the CDC and now Emory Vice President for Global Health and EGHI’s founding director. “There are a lot of different things that can cause respiratory failure. A lot of illnesses can lead to gastroenteritis and then death. The objective of this grant is to identify the specific causes of death so that we can develop programs to address them and save lives.”

CHAMPS is big: A $75 million investment for the first three years of a projected 20-year study, involving hundreds of partners at field sites and programmatic support from Emory, the CDC, and other Atlanta-based and international partners. But EGHI was created to serve as the mainframe for just such large-scale, long-term efforts—whether addressing high rates of maternal and childhood morbidity, understanding the spike of diabetes in developing nations, or increasing access to safe water.

Borders don’t mean much to infectious diseases, from shape-shifters like HIV and drug-resistant tuberculosis to sudden outbreaks like Ebola, SARS, or Zika. Chronic problems like diabetes and cardiovascular disease no longer belong primarily to richer, fatter nations but take an increasingly heavy toll on the economic stability, development, and even national security of developing nations, all with global impact.

Founded 10 years ago as the flagship program to expand Emory’s commitment to global health, EGHI is its own entity, university-wide, not part of any individual school. The organization is deliberately compact—a staff of ten, a cluster of offices, no big signs on the door. But its design—pragmatic, strategic, multidisciplinary, partner focused—gives it maximum flexibility in how to identify and tackle problems.

Read the whole article in Emory Magazine.

Related:
In Madagascar: A health crisis of people and their ecosystem

Monday, April 3, 2017

How babies see faces: New fMRI methods open window into infants' minds

“We’ve provided the first neural evidence that our basic mechanisms for face and place recognition are in place in infancy and only a little weaker than that of adults,” says Emory psychologist Daniel Dilks.

By Carol Clark

The ancient philosophers Descartes, Aristotle and Plato are among those who have pondered variations on the question: How much of our brain and mind are we born with and how much comes from being in the world?

“It’s an age-old debate, and one that we’re still having because it’s one of the most difficult questions to answer,” says Emory psychologist Daniel Dilks. “You can’t do controlled experiments to fully test the question in humans because you would have to take away a person’s experiences.”

Modern-day techniques, such as functional magnetic resonance imaging, or fMRI, offer a window into neural activity. Subjects must remain perfectly still and alert during scanning, however, making it difficult to do experiments with very young children. As a result, most measurements of children’s neural activity only go back to age four, at the earliest.

Until now, that is. As a post-doctoral fellow at MIT, Dilks was part of a team that successfully scanned the brains of awake human infants using fMRI. The researchers wanted to learn whether infants used similar neural mechanisms as adults to visually distinguish specific types of input, such as faces and objects.

“Two thirds of the adult brain is involved in visual processing, so the origins of how we process visual stimuli is particularly important to understanding the brain and the mind,” Dilks says.

The researchers adapted fMRI technology to make it baby friendly. They built a special fMRI head coil – the receiving antenna of the scanner – that allows a subject to recline in what resembles an infant car seat. A mirror attached to the seat allows a baby to watch videos while in the scanner. The researchers also muffled the noise of the scanner.

Using this technology, and other modifications, they conducted fMRI experiments on babies just four to six months old. The babies watched movies of faces and places and other stimulus categories while in the scanner, as data was collected on their neural activity. Their responses were then compared to those of adults.

The results, published this year by Nature Communications, found that the visual cortex of the infants responded preferentially to the categories of faces and places, with a spatial organization similar to adults. The adult responses, however, were more sensitive.

“We’ve provided the first neural evidence that our basic mechanisms for face and place recognition are in place in infancy and only a little weaker than that of adults,” Dilks says.

The work adds to the growing evidence that babies do not come into the world as what the ancient philosophers referred to as tabular rasa, or blank slates.

“Thirty years ago, we thought that infants were basically little sponges, absorbing everything around them,” Dilks says. “We now know that babies are full of knowledge really early — and we’re learning that some of that knowledge is pretty complex. It’s a big paradigm shift.”

Dilks has brought the fMRI scanning technology for infants and children to Emory, where his lab will build on the research to learn more about the development of visual processing. One goal is to map the progression of the category-selective visual cortex from infancy to adulthood. In addition to adding to basic scientific knowledge, the research may one day have medical applications.

“We can’t fix most neurological problems right now, partly because we don’t know enough about the brain,” Dilks says. “By continuing to learn more about how the brain develops and functions normally, we may keep moving closer to being able to repair it when something goes wrong.”

Related:
Babies have logical reasoning before age one
Dogs process faces in specialized brain area, study reveals 
How babies use numbers, space and time

Monday, March 20, 2017

Primate-parasite network analyses show how germs jump from host to host

A juvenile bonobo leaps from a branch. The bonobo, a threatened species of great ape found in the Congo Basin, is the closest existing relative to humans, along with the chimpanzee.

By Carol Clark

An extensive review of research on wild primate social networks and parasites underscores the importance of super-spreaders, or central individuals that play an outsized role in transmission of a pathogen.

Trends in Parasitology published the review, the first comprehensive synthesis of environmental and theoretical studies of disease dynamics in wild primate species — most of which are now threatened with extinction.

“This review gives critical insights that are applicable not just to conservation, but to our understanding of emerging infectious diseases and human health,” says Thomas Gillespie, lead author of the review and a primate disease ecologist at Emory University. “We hope it helps jump-start a new way of approaching research into disease transmission – one that integrates ecology, behavior and evolution on a grand scale.”

About 60 percent of the more than 500 known primate species face an extinction threat and more than three-fourths of them are on the decline, due to loss of habitat, hunting and disease. Large chunks of the world’s forests are succumbing to agriculture, mining and logging, bringing people, primates, pets and livestock into closer proximity. That juxtaposition sets the stage for more pathogens to jump between humans and our closest relatives. More than 20 percent of wild primate species harbor parasites capable of spilling over into humans. HIV, Ebola, yellow fever and respiratory viruses are examples of viruses shared by humans and wild primates.

“How an emerging pathogen spreads through a species tends to be ‘a black box’ until it causes an outbreak among people,” Gillespie says. The Zika virus, for instance, was first identified in monkeys in Uganda in 1947 but was not widely studied until recently, after it started sweeping through human populations.

Wild chimpanzees in Uganda's Kibale National Park. Chimpanzees, another threatened species of great ape, share 96 percent of human DNA. (Photo by Julie Rushmore)

Traditional infectious disease models generally assume that all individuals within a population have an equal probability of receiving or giving an infection, but more powerful analytical tools are showing that is not the case.

“Especially during the last decade,” Gillespie says, “it’s become much clearer that, just as everything in natural systems is heterogeneous, so is disease transmission.”

The so-called 80-20 rule – 80 percent of disease transmission events in an epidemic are caused by 20 percent of individuals – is now a well-established phenomenon. What’s not yet as well-understood are all of the variations within a disease system, and how these variations can combine to make an individual a super-spreader.

“Primate-parasite networks are an ideal model system for studying these questions,” Gillespie says, “because primate species are so varied and they have sophisticated social structures. We also have behavioral data for many primates – detailing the hierarchical ranking of individuals, and whom those individuals are related to and whom they interact with – collected over decades of observational studies.”

Combining knowledge of behaviors by individual species with data on their parasites can help researchers sort out high-risk traits and identify super-spreaders that contribute to transmission in a predictable way. Such patterns can help researchers to develop targeted interventions.

The review cites the example of a vaccine under development for Ebola virus, which is designed to replicate and spread immunity from a few individuals to others in a population. Targeting the most central individuals in an ape group with such a vaccine may be an effective way to mitigate future Ebola-related ape die-offs and spillover events into human populations.

The review also lays out a vision for the next decade of research into pathogen transmission, one that integrates ecology, behavior and evolution for studies of wild primates, other wildlife and humans.

“In addition to looking at how sociality influences infection, this review highlights the need to understand more about the flip side of that question: How do pathogens affect behavior and shape sociality?” Gillespie says. “We want to get people thinking about questions like this, in parallel networks of species.”

Co-authors of the review include Julie Rushmore of Oregon State University and the University of Georgia, and Donal Bisanzio of the University of Oxford.

Related:
Experts warn of impending extinction of many of the world's primates
Zeroing in on super-spreaders, and other hidden patterns of epidemics

Tuesday, March 7, 2017

Brain scans of service-dog trainees help sort weaker recruits from the pack

Some of the service dog trainees that were involved in the study pose with an fMRI scanner. (Photo by Gregory Berns.)

By Carol Clark

Brain scans of canine candidates to assist people with disabilities can help predict which dogs will fail a rigorous service training program, a study by Emory University finds.

The journal Scientific Reports published the results of the study, involving 43 dogs who underwent service training at Canine Companions for Independence (CCI) in Santa Rosa, California.

“Data from functional magnetic resonance imaging (fMRI) provided a modest, but significant, improvement in the ability to identify dogs that were poor candidates,” says Emory neuroscientist Gregory Berns, who led the research. “What the brain imaging tells us is not just which dogs are more likely to fail, but why.”

All of the dogs in the study underwent a battery of behavioral tests showing that they had a calm temperament before being selected for training. Despite calm exteriors, however, some of the dogs showed higher activity in the amygdala – an area of the brain associated with excitability. These dogs were more likely to fail the training program.

“The brain scans may be like taking a dog’s mental temperature,” Berns says. “You could think of it as a medical test with a normal range for a service dog. And the heightened neural activity that we see in the amygdala of some dogs may be outside of that range, indicating an abnormal value for a successful service dog.”

The findings are important, he adds, since the cost of training a service dog ranges from $20,000 to $50,000. As many as 70 percent of the animals that start a six-to-nine-month training program have to be released for behavioral reasons.

“There are long waiting lists for service dogs, and the training is lengthy and expensive,” Berns says. “So the goal is to find more accurate ways to eliminate unsuitable dogs earlier in the process.

The study found that fMRI boosted the ability to identify dogs that would ultimately fail to 67 percent, up from about 47 percent without the use of fMRI.

“This type of approach is not going to be feasible for individual trainers and their dogs because of the expense of fMRI,” Berns says. “It would only be practical for organizations that train large numbers of dogs every year.”

CCI is a non-profit that breeds, raises and trains dogs to assist human partners. Its service dog program, designed for disabled people, provides dogs to do tasks such as turn on lights, pick up dropped keys, open a door and pull a manual wheelchair.

Golden retrievers, Labradors — or crosses between the two — are the usual CCI service dog breeds, due to their generally calm and affable natures. After the puppies are weaned, they are adopted by volunteer puppy raisers for 15 months, before returning to CCI to undergo behavioral tests. Those that pass begin training.

For the Scientific Reports paper, the researchers taught the dogs how to remain still while undergoing an fMRI at the start of the training program.

The Berns lab was the first to conduct fMRI experiments on awake, unrestrained dogs, as part of an ongoing project to understand canine cognition and inter-species communication. In an early experiment, dogs were trained to respond to hand signals. One signal meant the dog would receive a food treat, and another signal meant that the dog would not receive one. The caudate region of the brain, associated with rewards in humans, showed activation when the dogs saw the signal for the treat, but not for the non-treat signal.

The researchers adapted this experiment for the current study — the largest yet involving dogs undergoing fMRI. The dogs were taught hand signals for “treat” and “no treat,” but sometimes the signals were given by the dog’s trainer and other times by a stranger.

The results found that dogs with stronger activity in the caudate in response to the treat signal – regardless of who gave the signal – were slightly more likely to successfully complete the service dog training program. However, if a dog had relatively more activity in the amygdala in response to the treat signal – particularly if the signal was given by a stranger – that increased the likelihood that the dog would fail.

“The ideal service dog is one that is highly motivated, but also doesn’t get excessively excited or nervous,” Berns says. “The two neural regions that we focused on – the caudate and the amygdala – seem to distinguish those two traits. Our findings suggest that we may be able to pick up variations in these internal mental states before they get to the level of overt behaviors.”

Berns hopes that the technology may become more refined and have applications for a broader range of working dogs, such as those used to assist the military and police forces.

Co-authors of the study include Andrew Brooks and Mark Spivak from Dog Star Technologies in Sandy Springs, Georgia, and Kerinne Levy from CCI.

Related:
What is your dog thinking? Brain scans unleash canine secrets
Dogs process faces in specialized brain area, study reveals

Monday, March 6, 2017

Atlanta Science Festival celebrates 'frontiers of the unknown'

Participants in the Zombie Outbreak Game scoured Peavine Creek on the Emory campus in 2016 for clues to the cause of a mock epidemic. The popular game returns this year on Sunday, March 19.

By Carol Clark

Watch for an astronaut, zombies, a hovercraft and liquid nitrogen ice cream to pop up on the Emory campus during the Atlanta Science Festival, March 14 to March 25. Thousands of science enthusiasts, of all ages, are also expected to appear for the fourth annual event – which includes lab tours, talks, a planetarium show, movie screenings, science-themed dance and games and lots more interactive fun.

The festival blasts off at Emory this year with a talk by NASA astronaut Mark Kelly. Tickets are going fast in the countdown to the event, set for 7 pm on Tuesday, March 14 at Glenn Memorial United Methodist Church.

“Emory University is proud to be a founder and strong supporter of the Atlanta Science Festival, which is just one example of the university’s engagement with our city and region,” says Emory President Claire E. Sterk. “We welcome the local community to our campus for the launch of the 2017 festival and to hear astronaut Captain Mark Kelly. Captain Kelly is an inspiration to all of us who are seeking to push the frontiers of the unknown.”

Name the ASF mascot
The title of Kelly’s talk is “Endeavor to Succeed.” He will give an insider’s perspective on space travel and the year-long NASA experiment he is participating in with his twin brother, also an astronaut, on how space affects the human body.

The public is invited to enter a contest to name the festival's new astronaut mascot. Entries are due by Friday, March 10 at 5 pm, and the winner will receive four VIP tickets to Kelly's talk.

Following are highlights of other festival events set at Emory.

“STEM Gems: Giving Girls Role Models in STEM Careers,” brings together women leaders from business, academia, NASA and more for a panel discussion on Thursday, March 16. They will offer advice aimed at girls ages 10 and up, who are interested in careers involving science, technology engineering or math.

The “Zombie Outbreak Game” returns to campus this year, on Sunday, March 19, giving participants ages 12 and up a chance to investigate a mock zombie disease outbreak, using real-world tools employed by scientists at Emory and the Centers for Disease Control and Prevention. Actors from Out of Hand Theater will play the patients as participants don masks and gowns and follow a trail of clues through streams, woods and labs across campus.

A dance performance, “Creating a New Normal: Race, Identity, Health and Activism,” will explore the themes involved in working towards an AIDS free generation, on the afternoon of Monday, March 20. The performance will be followed by a conversation with scientists and public health researchers — hosted by the Emory Center for Ethics — on the past, present and future of viral diseases.

“Investigating Our Human Past,” the evening of Monday, March 20, will allow visitors to examine the Emory Anthropology Department’s cast collection of fossilized skulls of our ancestors. Scientists will be on hand to discuss recent advances in our understanding of how the human brain evolved.

The Mathematics and Computer Science Department will present “Unveiling the Internet,” geared for teens, on the evening of Thursday, March 23. Participants will meet in a computer lab to tinker with code and learn concepts like how Snapchat snaps move through space.
Physics Live! set for Friday, March 24

The ever-popular “Physics Live!” returns to the Emory Math and Science Center on Friday, March 24. Children will be entertained with giant soap bubbles, a hovercraft and liquid nitrogen ice cream, among other activities. This year, the physics fun will be joined by a “Chemistry Carnival” at the Atwood Science Center. Chemists will turn into midway barkers, awarding prizes to visitors who play games like Peptide Jenga and Bacterial Telepathy, based on ongoing research in Emory labs.

The Oxford Campus will host a “Critter Crawl” through Oxford Forest on Sunday, March 19, to learn about wildlife native to Georgia. And on Sunday, March 21, an event called “It’s About Time” will bring guests and local researchers together to share scientific and social concepts of time.

In addition to on-campus events, members of the Emory community will be featured in Atlanta Science Festival activities happening throughout metro Atlanta:

“Science and Spirituality” will explore the intersections of physics and faith, biology and belief. The panel of local scientists and theologians will include Arri Eisen, a biologist from Emory’s Center for Ethics. On Thursday, March 16 at First Christian Church of Decatur.

“The Science Behind Tremors, the Movie,” features Emory paleontologist Tony Martin who will provide a lively discussion about real animals that inspired giant fictional worms. On Sunday, March 19 at Fernbank Science Center.

A live show and podcast called “You’re the Expert” will bring together a panel of comedians and podcast host Chuck Bryant, who will good-naturedly grill Emory chemist Cora McBeth about her work. On Tuesday, March 21 at 7 Stages Theatre.

The Exploration Expo, the culminating event of the festival, will include scientists from Emory biology, chemistry, environmental sciences, the Emory Herbarium and the Emory Center for the Study of Human Health. They will be among the hosts of 100 booths offering science-themed activities for families during the culminating event of the festival, set for Centennial Park on Saturday, March 25.

Monday, February 27, 2017

How protein misfolding may kickstart chemical evolution

The origami of disease, and of life: Research into the abnormal folding of proteins related to neurodegenerative conditions is providing insights into how life may emerge from a chemical system.

By Carol Clark

Alzheimer’s disease, and other neurodegenerative conditions involving abnormal folding of proteins, may help explain the emergence of life – and how to create it.

Researchers at Emory University and Georgia Tech demonstrated this connection in two new papers published by Nature Chemistry: “Design of multi-phase dynamic chemical networks” and “Catalytic diversity in self-propagating peptide assemblies.”

“In the first paper we showed that you can create tension between a chemical and physical system to give rise to more complex systems. And in the second paper, we showed that these complex systems can have remarkable and unexpected functions,” says David Lynn, a systems chemist in Emory’s Department of Chemistry who led the research. “The work was inspired by our current understanding of Darwinian selection of protein misfolding in neurodegenerative diseases.”

The Lynn lab is exploring ways to potentially control and direct the processes of these proteins – known as prions – adding to knowledge that might one day help to prevent disease, as well as open new realms of synthetic biology. For the current papers, Emory collaborated with the research group of Martha Grover, a professor in the Georgia Tech School of Chemical & Biomolecular Engineering, to develop molecular models for the processes.

“Modeling requires us to formulate our hypotheses in the language of mathematics, and then we use the models to design further experiments to test the hypotheses,” Grover says.

Darwin’s theory of evolution by natural selection is well-established – organisms adapt over time in response to environmental changes. But theories about how life emerges – the movement through a pre-Darwinian world to the Darwinian threshold – remain murkier.

The researchers started with single peptides and engineered in the capacity to spontaneously form small proteins, or short polymers. “These protein polymers can fold into a seemingly endless array of forms, and sometimes behave like origami,” Lynn explains. “They can stack into assemblies that carry new functions, like prions that move from cell-to-cell, causing disease.”

This protein misfolding provided the model for how physical changes could carry information with function, a critical component for evolution. To try to kickstart that evolution, the researchers engineered a chemical system of peptides and coupled it to the physical system of protein misfolding. The combination results in a system that generates step-by-step, progressive changes, through self-driven environmental changes.

“The folding events, or phase changes, drive the chemistry and the chemistry drives the replication of the protein molecules,” Lynn says. “The simple system we designed requires only the initial intervention from us to achieve progressive growth in molecular order. The challenge now becomes the discovery of positive feedback mechanisms that allow the system to continue to grow.”

The research was funded by the McDonnell Foundation, the National Science Foundation’s Materials Science Directorate, Emory University’s Alzheimer’s Disease Research Center, the National Science Foundation’s Center for Chemical Evolution and the Office of Basic Energy Sciences of the U.S. Department of Energy.

Additional co-authors of the papers include: Toluople Omosun, Seth Childers, Dibyendu Das and Anil Mehta (Emory Departments of Chemistry and Biology); Ming-Chien Hsieh (Georgia Tech School of Chemical and Biomolecular Engineering); and Neil Anthony and Keith Berland (Emory Department of Physics).

Related:
Peptides may hold 'missing link' to life

Monday, February 20, 2017

Contact tracing, with indoor spraying, can curb dengue outbreak

A traditional Queenslander home in Cairns, Australia, is open to breezes, as well as to disease-bearing mosquitoes. (Photo via James Cook University.)

By Carol Clark

Contact tracing, combined with targeted, indoor residual spraying of insecticide, can greatly reduce the spread of the mosquito-borne dengue virus, finds a study led by Emory University.

In fact, this novel approach for the surveillance and control of dengue fever – spread by the same mosquito species that infects people with the Zika virus – was between 86 and 96 percent effective during one outbreak, the research shows. By comparison, vaccines for the dengue virus are only 30-to-70-percent effective, depending on the serotype of the virus.

Science Advances published the findings, which were based on analyses from a 2009 outbreak of dengue in Cairns, Australia.

“We’ve provided evidence for a method that is highly effective at preventing transmission of diseases carried by the Aedes aegypti mosquito in a developed, urban setting,” says the study’s lead author, Gonzalo Vazquez-Prokopec, a disease ecologist in Emory’s Department of Environmental Sciences. “We’ve also shown the importance of human movement when conducting surveillance of these diseases.”

“The United States is facing continual threats from dengue, chikungunya and Zika viruses,” says Sam Scheiner, director of the National Science Foundation’s Ecology and Evolution of Infectious Diseases Program, which funded the research. “For now, the response is to intensively spray insecticides. This research shows that a more targeted approach can be more effective.”

While the method would likely not be applicable everywhere, Vazquez-Prokopec says that it may be viable to control Aedes-borne diseases in places with established health systems and similar environmental characteristics to Cairns, such as South Florida or other U.S. states at risk of virus introduction.

“The widespread transmission of dengue viruses, coupled with the birth defects associated with Zika virus, shows the dire need for as many weapons as possible in our arsenal to fight diseases spread by these mosquitos,” he says. “Interventions need to be context dependent and evaluated carefully and periodically.”

A public health worker collects Aedes mosquito larvae from water that has pooled on a tarp at a residence in Cairns, Australia.

During the dengue outbreak in Cairns, public health officials traced recent contacts of people with a confirmed infection – a surveillance method known as contact tracing. This method is commonly used for directly transmitted pathogens like Ebola or HIV, but rarely for outbreaks spread by mosquitos or other vectors.

Using mobility data from the known cases, public health workers targeted residences for indoor residual spraying, or IRS. Walls of the homes – from top to bottom – and dark, humid places were Aedes mosquitos might rest, were sprayed with an insecticide that lasts for months.

The method is time-consuming and labor intensive, and health officials were not able to reach all of the residences that were connected to the infected persons.

The researchers found that performing IRS in potential exposure locations reduced the probability of dengue transmission by at least 86 percent in those areas, in comparison to areas of potential exposures that did not have indoor spraying.

“The findings are important,” Vazquez-Prokopec says, “because they demonstrate one of the few measures that we have for the effectiveness of an intervention to reduce the transmission of dengue.”

Many times, he says, in the face of a dengue outbreak public health officials end up using trucks to spray insecticide – despite the lack of scientific evidence for the effectiveness of fogging from the streets to control Aedes aegypti mosquitos.

Quantifying the effectiveness of existing methods, and the context within which they work, can strengthen the vector-control arsenal. “We need to develop plans for outbreak containment that are context-specific,” Vazquez-Prokopec says.

He is researching ways to scale up this intervention. While it now takes approximately half-an-hour to conduct indoor residual spraying in a single house, he would like to cut that time to as little as 10 minutes.

“We are evaluating how we can scale up and improve IRS for 21st-century urban areas,” Vazquez-Prokopec says.

Co-authors of the study include researchers from Queensland Health, the Rollins School of Public Health and James Cook University, Cairns.

Related:
Zeroing in on 'super spreaders' and other hidden patterns of epidemics
Human mobility data may help curb urban epidemics

Friday, February 17, 2017

How dads bond with toddlers: Brain scans link oxytocin to paternal nurturing

The findings show that "fathers, and not just mothers, undergo hormonal changes that are likely to facilitate increased empathy and motvation to care for their children," says Emory anthropologist James Rilling.

By Carol Clark

Fathers given boosts of the hormone oxytocin show increased activity in brain regions associated with reward and empathy when viewing photos of their toddlers, an Emory University study finds. 

“Our findings add to the evidence that fathers, and not just mothers, undergo hormonal changes that are likely to facilitate increased empathy and motivation to care for their children,” says lead author James Rilling, an Emory anthropologist and director of the Laboratory for Darwinian Neuroscience. “They also suggest that oxytocin, known to play a role in social bonding, might someday be used to normalize deficits in paternal motivation, such as in men suffering from post-partum depression.”

The journal Hormones and Behavior published the results of the study, the first to look at the influence of both oxytocin and vasopressin – another hormone linked to social bonding – on brain function in human fathers.

A growing body of literature shows that paternal involvement plays a role in reducing child mortality and morbidity, and improving social, psychological and educational outcomes. But not every father takes a “hands-on” approach to caring for his children.

“I’m interested in understanding why some fathers are more involved in caregiving than others,” Rilling says. “In order to fully understand variation in caregiving behavior, we need a clear picture of the neurobiology and neural mechanisms that support the behavior.”

Researchers have long known that when women go through pregnancy they experience dramatic hormonal changes that prepare them for child rearing. Oxytocin, in particular, was traditionally considered a maternal hormone since it is released into the bloodstream during labor and nursing and facilitates the processes of birth, bonding with the baby and milk production.

More recently, however, it became clear that men can also undergo hormonal changes when they become fathers, including increases in oxytocin. Evidence shows that, in fathers, oxytocin facilitates physical stimulation of infants during play as well as the ability to synchronize their emotions with their children.

In order to investigate the neural mechanisms involved in oxytocin and paternal behavior, the Rilling lab used functional Magnetic Resonance Imaging (fMRI) to compare neural activity in men with and without doses of oxytocin, administered through a nasal spray. The participants in the experiment were all healthy fathers of toddlers, between the ages of one and two. While undergoing fMRI brain scans, each participant was shown a photo of his child, a photo of a child he did not know and a photo of an adult he did not know.

When viewing an image of their offspring, participants dosed with oxytocin showed significantly increased neural activity in brain systems associated with reward and empathy, compared to placebo. This heightened activity (in the caudate nucleus, dorsal anterior cingulate and visual cortex) suggests that doses of oxytocin may augment feelings of reward and empathy in fathers, as well as their motivation to pay attention to their children.

Surprisingly, the study results did not show a significant effect of vasopressin on the neural activity of fathers, contrary to the findings of some previous studies on animals.

Research in prairie voles, which bond for life, for instance, has shown that vasopressin promotes both pair-bonding and paternal caregiving. “It could be that evolution has arrived at different strategies for motiving paternal caregiving in different species,” Rilling says.

Co-authors of the study include Ting Li (Emory Anthropology), Xu Chen (Emory Anthropology and the School of Medicine’s Department of Psychiatry and Behavioral Sciences), Jennifer Mascaro (Emory School of Medicine Department of Family and Preventive Medicine) and Ebrahim Haroon (Department of Psychiatry and Behavioral Sciences)

Related:
Testes size correlates with men's involvement in toddler care
A brainy time traveler

Friday, February 10, 2017

Brazilian peppertree packs power to knock out antibiotic-resistant bacteria

The weed whisperer: Ethnobotanist Cassandra Quave uncovered a medicinal mechanism in berries of the Brazilian peppertree. The plant is a weedy invasive species in Florida, but valued by traditional healers in the Amazon as a treatment for infections. (Photos by Ann Bordon, Emory Photo/Video)

By Carol Clark

The red berries of the Brazilian peppertree – a weedy, invasive species common in Florida – contain an extract with the power to disarm dangerous antibiotic-resistant staph bacteria, scientists at Emory University have discovered.

The journal Scientific Reports published the finding, made in the lab of Cassandra Quave, an assistant professor in Emory’s Center for the Study of Human Health and in the School of Medicine’s Department of Dermatology.

“Traditional healers in the Amazon have used the Brazilian peppertree for hundreds of years to treat infections of the skin and soft tissues,” Quave says. “We pulled apart the chemical ingredients of the berries and systematically tested them against disease-causing bacteria to uncover a medicinal mechanism of this plant.”

Brazilian peppertree, Schinus terebinthifolia
The researchers showed that a refined, flavone-rich composition extracted from the berries inhibits formation of skin lesions in mice infected with methicillin-resistant Staphylococcus auereus (MRSA). The compound works not by killing the MRSA bacteria, but by repressing a gene that allows the bacteria cells to communicate with one another. Blocking that communication prevents the cells from taking collective action, a mechanism known as quorum quenching.

“It essentially disarms the MRSA bacteria, preventing it from excreting the toxins it uses as weapons to damage tissues,” Quave says. “The body’s normal immune system then stands a better chance of healing a wound.”

The discovery may hold potential for new ways to treat and prevent antibiotic-resistant infections, a growing international problem. Antibiotic-resistant infections annually cause at least two million illnesses and 23,000 deaths in the United States, according to the Centers for Disease Control and Prevention. The United Nations last year called antibiotic-resistant infections a “fundamental threat” to global health and safety, citing estimates that they cause at least 700,000 deaths each year worldwide, with the potential to grow to 10 million deaths annually by 2050.

Blasting deadly bacteria with drugs designed to kill them is helping to fuel the problem of antibiotic resistance. Some of the stronger bacteria may survive these drug onslaughts and proliferate, passing on their genes to offspring and leading to the evolution of deadly “super bugs.”

In contrast, the Brazilian peppertree extract works by simply disrupting the signaling of MRSA bacteria without killing it. The researchers also found that the extract does not harm the skin tissues of mice, or the normal, healthy bacteria found on skin.

“In some cases, you need to go in heavily with antibiotics to treat a patient,” Quave says. “But instead of always setting a bomb off to kill an infection, there are situations where using an anti-virulence method may be just as effective, while also helping to restore balance to the health of a patient. More research is needed to better understand how we can best leverage anti-virulence therapeutics to improve patient outcomes.”

Quave, a leader in the field of medical ethnobotany and a member of the Emory Antibiotic Resistance Center, studies how indigenous people incorporate plants in healing practices to uncover promising candidates for new drugs.

Cassandra Quave with her lab manager James Lyles, a co-author of the Brazilian peppertree study and a post-doctoral fellow at Emory.

The Brazilian peppertree (Schinus terebinthifolia) is native to South America but thrives in subtropical climates. It is abundant in much of Florida, and has also crept into southern areas of Alabama, Georgia, Texas and California. Sometimes called the Florida holly or broad leaf peppertree, the woody plant forms dense thickets that crowd out native species.

“The Brazilian peppertree is not some exotic and rare plant found only on a remote mountaintop somewhere,” Quave says. “It’s a weed, and the bane of many a landowner in Florida.”

From an ecological standpoint, it makes sense that weeds would have interesting chemistry, Quave adds. “Persistent, weedy plants tend to have a chemical advantage in their ecosystems, which may help protect them from diseases so they can more easily spread in a new environment.”

The study's co-authors include Amelia Muhs and James Lyles (Emory Center for the Study of Human Health); Kate Nelson (Emory School of Medicine); and Corey Parlet, Jeffery Kavanaugh and Alexander Horswill (University of Iowa). The laboratory experiments were conducted in collaboration between the Quave and Horswill labs with funding from the National Center for Complementary and Integrative Health, National Institutes of Health.

The Quave lab is now doing additional research to confirm the safest and most effective means of using the Brazilian peppertree extract. The next step would be pre-clinical trials to test its medicinal benefits. “If the pre-clinical trials are successful, we will apply for an application to pursue clinical trials, under the Food and Drug Administration’s botanical drug pathway,” Quave says.

The Brazilian peppertree finding follows another discovery made by the Quave lab in 2015: The leaves of the European chestnut tree also contain ingredients with the power to disarm staph bacteria without increasing its drug resistance.

While both the Brazilian peppertree and chestnut tree extracts disrupted the signaling needed for quorum quenching, the two extracts are made up of different chemical compounds.

“The latest classes of antibiotics introduced to the market were actually discovered between the 1950s and 1980s,” Quave says. “Scientists have just been building off the same building blocks of earlier classes and modifying them slightly to create new antibiotics. Examining the extracts of plants used by traditional healers for infections may open up discovery of new chemical scaffolds for drug design, and provide important pathways for battling antibiotic-resistance.”

Related:
Chestnut leaves yield extract that disarms deadly bacteria
Tapping traditional remedies to fight modern super bugs
A future without antibiotics?

Monday, February 6, 2017

Astronaut Mark Kelly to launch Atlanta Science Festival at Emory

Captain Mark Kelly, who led NASA missions into space, will lead off the action-packed schedule of this year's Atlanta Science Festival on Tuesday, March 14. His talk is entitled "Endeavor to Succeed." (NASA photo)

By Carol Clark

The 2017 Atlanta Science Festival blasts off on Tuesday, March 14 with a talk by Captain Mark Kelly – commander of Space Shuttle Endeavour’s final mission – at 7 pm in Emory’s Glenn Memorial Auditorium.

“We wanted to start off this year with someone who appeals to people of all ages and who epitomizes science in action,” says Meisa Salaita, co-executive director of the Atlanta Science Festival, which will continue through March 25 with events throughout the metro area. “Who better than an astronaut to show us how science can take us to new and exciting places?”

The title of Kelly’s talk is “Endeavour to Succeed.” Tickets for the event can be bought in advance on the Atlanta Science Festival’s web site for $12 ($8 for children 12 and under). They will also be available at the door the day of the event for $15.

Starting at 5:30 pm, during the countdown to Kelly’s talk, the public is invited to join toy rocket launching activities on the Glenn Memorial lawn, led by members of the Georgia Tech Ramblin’ Rocket Club and the Institute of Electronic and Electrical Engineers.

Kelly, who began his NASA career in 1996, commanded the Space Shuttle Discovery, as well as the Endeavour. He left the astronaut corps in the summer of 2011 to help his wife, former U.S. Congresswoman Gabrielle Giffords, recover from gunshot wounds she received in an assassination attempt on her life. The couple’s story captivated the nation, and they went on to found Americans for Responsible Solutions to advocate for gun control.

NASA is comparing biological data from the Earth-bound Kelly with his identical twin brother, Scott Kelly, who recently spent a year in space. The unique Twins Study may offer insights into how to prepare astronauts for a long-term mission to Mars.

Kelly is also a prolific author, including numerous children’s books with space themes, and he will be available for a book signing following his talk at Emory.

The 12-day Atlanta Science Festival features talks, lab tours, film screenings, participatory activities and science demonstrations — more than 100 events at dozens of different venues, including the Emory campus. “We’ve expanded the number of days at the festival of the year, to avoid scheduling conflicts and give people a chance to experience more of the festival,” Salaita says. (Click here for the full schedule of events.)

Physics Live (at the Emory Mathematics and Science Center) and a Chemistry Carnival (at the Atwood Chemistry Center) will be among the Emory campus highlights, featuring lab tours and science demonstrations from 3:30 to 7 pm on Friday, March 24. (Click here for a full listing of Emory-related events.)

New at the festival this year will be an appearance by New York rap artist Baba Brinkman. He will perform “Rap Guide to Climate Chaos” at 1:30 on Saturday, March 18 at the Drew Charter School. 

Also new this year is “The Art and Science of Cooking with Insects,” featuring free tastings, at 7:30 pm on Thursday, March 23 at Manuels Tavern.

About 20,000 visitors are expected for the festival’s culminating event, the Exploration Expo, from 11 am to 4 pm on Saturday, March 25 at Centennial Olympic Park. Around 100 interactive exhibits will delight curious minds of all ages, from Emory chemist’s Doug Mulford’s “Ping Pong Big Bang” to the immersive Google Village experience.

Leading sponsors of this year’s Atlanta Science Festival include Emory, Georgia Tech, the Metro Atlanta Chamber, Delta Airlines and Google.

Thursday, February 2, 2017

If you dig survival, read 'The Evolution Underground'

"Some animals were born to run. Others were born to burrow," says Emory paleontologist Anthony Martin, shown with the cast of a crustacean burrow from the Georgia coast. (Photo by Lisa Streib.)

By Carol Clark

The dirt flies in Emory paleontologist Anthony Martin’s new tell-all book, “The Evolution Underground: Burrows, Bunkers and the Marvelous Subterranean World Beneath Our Feet.” The book takes readers on a head-spinning tour of the underworld, from the tiny tunnels drilled by modern-day earthworms to the massive, four-meter-wide paleo-burrows excavated by the Pleistocene’s giant sloths.

“I want people to understand how the evolution of burrowing has shaped the environments we see today, from the ocean floor to high mountaintops,” Martin says. “Burrowing strategies are also key to the survival of many species – beyond just the burrowers themselves.”

Martin is a leading expert of ichnology – the study of trace fossils, including burrows, nests, tracks and feces. “The Evolution Underground,” published by Pegasus Books, is Martin’s seventh book, and his second aimed at a general audience, after 2014’s “Dinosaurs Without Bones.”

In the following interview, he reveals some of nature’s deepest, darkest secrets.

Q. When did burrowing behaviors begin in animals? 

Tony Martin: The earliest evidence we have for burrowing goes back 550 million years, with marine animals. But these early burrowers, including trilobites, didn’t go very deep. If you think of the sea floor like a carpet, they were digging into the top of it or just beneath it, probably mining the sediment for food.

Around 545 million years ago, trilobites, marine worms and other invertebrates starting going deeper, burrowing vertically. They were probably both seeking organic particles for food and shelter against predators. Soon after that, predators started burrowing and the arms race was on.

Map of tunnel system made by Pleistocene giant ground sloths. U.S.S. Enterprise shuttlecraft (7 meters/23 feet long) for scale. (Figure by Anthony Martin.)

Q. How did these burrowers impact the environment? 

TM:
By punching down into the seabed, they put oxygen down into sediment that normally wasn’t exposed to it. That started oxidizing elements on the ocean floor, changing the carbon, phosphorous, nitrogen and sulphur cycles. So burrowing changed the ocean chemistry, which in turn had an influence on atmospheric chemistry. These early burrowers were ecosystem engineers.

They were also highly adaptable. The invasion of land by ocean life may have been facilitated by burrowing, enabling some species to make the transition to a new environment.

Q. So burrowers were the original survivalists? 

TM:
Yes! Burrowing enabled animals to make it through the worst that Earth threw at them – or even the worst that the solar system threw at them. A lot of animals, for example, lived after a large asteroid impact killed off the dinosaurs 66 million years ago. Why did they survive? They were in their bunkers! It’s likely there were other factors, but burrowing is definitely an advantage when you get a giant space rock dropped on you.

There are modern examples, as well. After the 1980 eruption by Mount St. Helens, scientists flew over this barren, smoldering wasteland in helicopters. All the largest animals were gone. One of the only signs of life was the tops of pocket gopher burrows. Ecologists determined that pocket gophers didn’t just survive the explosion, they helped the entire ecosystem come back. They mined the soil and brought up seeds from below, restoring vegetation. And their burrows provided microhabitats for reptiles and amphibians in the area.

Pocket gophers aren’t the only ecological heroes. Gopher tortoises dig burrows six-meters deep and create an underground zoo of diversity. Some 300-to-400 species live alongside the tortoises in their burrows, including indigo snakes, the longest snake native to North America, and rattlesnakes.

Behold an ecological hero — the pocket gopher! (Photo by Ty Smedes, Washington Department of Fish and Wildlife.)

Q. Do any animals stand out as the best burrowers? 

TM:
It depends on how you define “best,” but when it comes to the amount of soil overturned, ants are the rulers of the underground. Leafcutter ants create these spiral, vertical shafts that go down two meters and branch into a labyrinth of tunnels that connect to outer chambers. A recent excavation of a leafcutter colony in Brazil showed that these tiny insects had to move about 40 tons of soil to create their underground city. That’s the ant equivalent of the Great Wall of China, in terms of the effort that went into it. And that’s just a single ant colony. Especially compared to their size, ants have a disproportionate impact on ecosystems.

Q. What about human burrowing behaviors? 

TM:
Humans also burrow to survive predation and environmental extremes. The massive underground cities carved out of volcanic ash in Cappadocia, Turkey, during Byzantine times served as safe havens during times of war. Fears of nuclear warfare during the Cold War prompted the U.S. military to build networks of underground bunkers.

Montreal’s The Underground City was created mainly to deal with Canada’s long winters. People live, shop and go to the office while staying in a climate-controlled environment. And in the opal-mining town of Coober Pedy, in the Outback of Australia, people have adapted to the scorching heat by building underground houses.

We can learn a lot from burrowers of the geologic past, as well as the burrowing animals of today. If you want to survive a mass extinction, for example, you should probably start digging.

Related:
Bringing to life 'Dinosaurs Without Bones'
Dinosaur burrows yield clues to climate change
Lake bed trails tell ancient fish story

Thursday, January 19, 2017

Experts warn of impending extinction of many of the world's primates

The black-and-white ruffed lemur of Madagascar is endangered due to hunting and to habitat loss. Most primates live in regions with high levels of human poverty and inequality, which contributes to the decline of the animals, says Thomas Gillespie, an Emory expert in the disease ecology of primates.

By Carol Clark

Urgent action is needed to protect the world’s dwindling primate populations, warns a group of 31 leading experts on primate conservation in Science Advances. Sixty percent of the more than 500 primate species worldwide are threatened with extinction, while more than 75 percent have declining populations, the landmark article reports. The authors include scientists and policymakers from the United States, Europe, Asia, Latin America and Africa.

“The majority of primate species are endangered now. We are at a turning point where we must take action or lose many species during the next 50 years,” says co-author Thomas Gillespie, an associate professor in Emory University’s Department of Environmental Sciences and an expert in the disease ecology of primates.
A young orangutan

“Primates are our closest relatives and make up a large proportion of the mammals of the world,” he adds. “If we lose them, not only do we lose a lot of insights into ourselves, we lose the ecological services that they provide.”

The order primates – ranging from the tiny mouse lemurs of Madagascar to the massive mountain gorillas of Central Africa – is the third most diverse order of mammals, after rodents and bats. Primate species serve as seed dispersers, pollinators, predators and prey to keep ecosystems in balance. For instance, other rare animals – such as jaguars, leopards and harpy eagles – include monkeys in their diets.

Primates are so prevalent in zoos and in media imagery, many people are lulled into a false sense of security and do not realize how scarce they are becoming, Gillespie says.

The Science Advances article details how escalating human activities are putting unsustainable pressures on primates and their habitats, including extensive forest loss due to the expansion of industrial agriculture and large-scale catting ranching, logging, oil and gas drilling, mining, dam building and the construction of road networks for resource extraction.

In addition to habitat loss and poaching, disease is a major threat to many primate populations, and is often intertwined with the other two issues, Gillespie says. “It’s important to try to keep primate habitats as intact as possible,” he says, “because when they become fragmented primates may be forced to come out and raid agricultural crops just to get enough to eat. And crop raiding leads to all kinds of conflict, such as fights between dogs and primates, and opportunities for fecal contamination.”

A young chimpanzee in Gombe Stream National Park, where human misuse of antibiotics is putting the animals at risk for antibiotic-resistant bacterial infections. "If you help a local human population become healthier, you also reduce the potential for infectious disease in the surrounding wildlife," Gillespie says.

Disease is the main threat to the survival of the endangered chimpanzees of Tanzania’s Gombe Stream National Park, made famous by the work of primatologist Jane Goodall, who began observing them during the 1960s.

Work by Gillespie and his colleagues has found that human misuse of antibiotics is putting the Gombe chimpanzees at risk for antibiotic-resistant bacterial infections. The Gillespie lab is one of the few investigating the ecology and epidemiology of infectious disease in natural systems where domesticated animals, humans and wildlife overlap.

Among the pathogens threatening both humans and non-human primates are the malaria species Plasmodium knowlesi, which can cause disease in pigtail macaques in Southeast Asia; Ebola, which affects chimpanzees and gorillas in Africa; and yellow fever, which strikes brown howler monkeys in South America.

Most primates live in regions with high levels of human poverty and inequality, and the co-authors stress the need to improve human health and access to education, while also preserving traditional livelihoods that can contribute to food security and environmental conservation.

“If you help a local human population become healthier, you also reduce the potential for infectious disease in the surrounding wildlife,” Gillespie says.

The authors are calling on governmental officials, scientists, non-governmental organizations, businesses and individual citizens to mobilize and raise awareness of the plight of the world’s primates.

“If humans continue to alter and degrade habitats such that they are unsuitable for our primate relatives, then these habitats will eventually become unsuitable for ourselves,” they conclude.

Related:
In Madagascar, a health crisis of people and their ecosystem
Disease poses risk to chimpanzee conservation, Gombe study finds
Sanctuary chimps show high rates of drug-resistant staph

Wednesday, January 18, 2017

Neuro-imaging maps brain wiring of extinct Tasmanian tiger

An 1862 illustration of the thylacine, or Tasmanian tiger. The extinct marsupial had dog-like features, along with tiger-like stripes and an abdominal pouch. "The thylacine brain is very different than the canine brain, despite the physical resemblance of their bodies," says Emory neuroscientist Gregory Berns.

By Carol Clark

Scientists have used an imaging technique to reconstruct the brain architecture and neural networks of the thylacine – better known as the Tasmanian tiger – an extinct carnivorous marsupial native to Tasmania. The study, published in PLOS ONE, used magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to scan postmortem specimens of two thylacine brain specimens, both of which were about 100 years old.

The results, when compared to the Tasmanian tiger’s closest living relative, the Tasmanian devil, suggest that the larger-brained thylacine had more cortex devoted to planning and decision-making. 

“The natural behavior of the thylacine was never scientifically documented,” says Gregory Berns, a neuroscientist at Emory University and the lead author of the study. “Our reconstruction of its white matter tracts, or neural wiring, between different regions of its brain is consistent with anecdotal evidence that the thylacine occupied a more complex, predatory ecological niche versus the scavenging niche of the Tasmanian devil.”

The comparative study also supports theories of brain evolution suggesting that as brains grow larger they become more modular, or divided into sections associated with discrete functions, Berns says. 

Kenneth Ashwell, an anatomist at the University of New South Wales School of Medical Sciences and an expert on the brain evolution of marsupials and monotremes, co-authored the study.

“The technology for imaging the preserved brains of rare, extinct and endangered species is an exciting innovation in the study of brain evolution,” Ashwell says. “It will allow us to track pathways and study functional connections that could never be analyzed through older experimental techniques.”

Image shows the reconstruction of the neural pathways of the Tasmanian devil (left) and the Tasmanian tiger, or thylacine (right). (Image courtesy Gregory Berns).

Monotremes, such as the egg-laying platypus, are remnants of the first mammals, going back more than 150 million years. Marsupials formed a later branch of mammals, including the best-known example, the kangaroo. Instead of laying eggs, they bear relatively undeveloped young that must be carried in a mother’s pouch.

The Tasmanian tiger looked like an amalgam of several animals. It is one of only a few marsupials to have a pouch in both sexes. It was the size and shape of a medium-to-large size dog, but had tiger-like stripes running down its lower back and an abdominal pouch. Its Greek name, Thylacinus cynocephalus, means “dog-headed pouched one.”

The fossil record shows that the Tasmanian tiger appeared about four million years ago in Australia. By the 20th century it was extinct, or extremely rare, on the mainland but was still found in Tasmania, the island state off Australia’s southern coast. Its demise is attributed to loss of habitat through farming activity, coupled with a bounty scheme placed on the animal after it was suspected of killing sheep and other livestock. The last known Tasmanian tiger died in 1936, in Tasmania’s Hobart Zoo.
Tasmanian devil, top, and thylacine (1808)

The Tasmanian devil, another iconic animal of Tasmania, is now the island’s largest surviving carnivorous marsupial. It is known for its powerful jaws and scream-like vocalizations. Tasmanian devils are also unique because they suffer from devil facial tumor disease – an infectious, non-viral parasitic cancer which they can transmit to one another through fighting. While the unusual disease makes the animals of interest to cancer researchers, it is threatening the survival of the remaining Tasmanian devils, whose wild population has declined by 70 percent during the past 20 years.

Berns, who was the first to conduct MRI experiments on awake, unrestrained dogs to learn more about their neural processes, was particularly intrigued by the thylacine due to its physical resemblance to dogs.

“The thylacine appears to be an example of convergent evolution, filling a similar niche that members of the canid family did elsewhere,” Berns says. “It’s interesting, however, that the thylacine brain is very different than the canine brain, despite the physical resemblance of their bodies.”

Only four surviving specimens of the brains of Tasmanian tigers exist, and the study gained access to two of them. One was provided by the Smithsonian Institution, taken from a male Tasmanian tiger after it died at the National Zoological Park in 1905. The other specimen, loaned to the researchers by the Australian Museum in Sydney, came from an animal that died during the 1930s.

The two Tasmanian devil brains used in the study included one from the Smithsonian Institution, which had been preserved around the same time as its Tasmanian tiger specimen. The other specimen came from a recently deceased animal and was supplied by the Save the Tasmanian Devil Program, a conservation initiative of the Australian and Tasmanian governments.

A male and female thylacine in the National Zoo of Washington D.C., circa 1904. (Photo by E. J. Baker, from the Smithsonian Institution archives).

MRI scans reveal information about the architecture of a brain – known as gray matter. Diffusion tensor imaging (DTI) provides information about how molecules move through biological tissues, revealing the connective pathways of a brain – known as white matter.

The technique of using DTI on a non-living brain is mainly applied to research on recently deceased humans, primates and rats. Berns is pioneering the use of a special form of DTI to digitally reconstruct the neural networks of other animals, using archived brain specimens from zoological and museum collections.

In 2015, Berns successfully used DTI on two decade-old specimens to map the sensory and motor systems of the brains of dolphins for the first time. The results showed how at least two areas of the dolphin brain are associated with the auditory system, unlike most mammals that primarily process sound in a single area.

The current digital reconstruction of the brain of the Tasmanian tiger is particularly important, Berns says, not just because the animal is extinct but because the specimens used were much older than those of the dolphins.

“While it is easier to study the brains of animals that have recently died, we’ve shown that we can successfully use our scanning techniques on specimens that are 100 years old,” Berns says. “We now have the technology available to make use of the treasure trove of museum collections around the world.”

Berns launched a project called the Brain Ark, a digital archive of high-resolution, three-dimensional brain structures of megafauna, which is publicly accessible via the web so that other researchers can contribute to and draw from the data. It currently includes the scans from the dolphins, Tasmanian tigers and Tasmanian devils.

The digital resource will allow researchers to explore questions about brain evolution, including how brain structure is related to species-specific attributes such as being primarily a predator or prey, foraging strategies, ecological niches and sexual dimorphisms.

“We know a lot about the brains of primates and rats, but there are a lot of other animal brains out there that no one has looked at in any kind of detail,” Berns says. “The Brain Ark is going to fill that gap. We are living in a time when much of the planet’s megafauna is at risk for extinction. It’s important to gather as much data as we can before many of these animals disappear.”

Related:
First images of dolphin circuitry hint at how they sense sound
Brain scans unleash canine secrets