Pursuit Of Bird Brains Takes Researchers Back 66 Million Years

A handful of bird species survived the K-T extinction. Chicken genomes have changed the least since that terrible day.

A handful of bird species survived the K-T extinction. Chicken genomes have changed the least since that terrible day.

By Karl Leif Bates

In the beginning was the Chicken. Or something quite like it.

At that moment 66 million years ago when an asteroid impact caused the devastating Cretaceous–Tertiary (K-T) extinction, a handful of bird-like dinosaur species somehow managed to survive.

The cataclysm and its ensuing climate change wiped out much of Earth’s life and brought the dinosaurs’ 160-million-year reign to an end.

But this week, the genomes of modern birds are telling us that a few resourceful survivors somehow scratched out a living, reproduced (of course), and put forth heirs that evolved to adapt into all the ecological niches left vacant by the mass extinction. From that close call, birds blossomed into the more than 10,000 spectacularly diverse species we know today.

Erich Jarvis

Erich Jarvis

Not all birds are descended from chickens, but it’s true that chicken genes have diverged the least from the dinosaur ancestors, says Erich Jarvis, an associate professor of neurobiology in the Duke Medical School and Howard Hughes Medical Institute Investigator.

He’s one of the leaders on a gigantic release of scientific data and papers that tells the story of the plucky K-T survivors and their descendants, redrawing many parts of the bird family tree.

From giant, flightless ostriches to tiny, miraculous hummingbirds, the descendants of those proto-birds now rule over the skies, the forests, the cliff-faces and prairies and even under water. While other birds were learning to reproduce songs and sounds, hover to drink nectar, dive on prey at 230 miles per hour, run across the land at 40 miles per hour, migrate from pole to pole or spend months at sea out of sight of land, the chickens just abided, apparently.

terror birds

Sweet little chickadees had a very big, very scary cousin. “Parrots and songbirds and hawks and eagles had a common ancestor that was an apex predator,” Erich Jarvis says. “We think it was related to these giant ‘terror birds’ that lived in the South American continent millions of years ago.”

The new analyses released this week are based on complete-genome sequencing done mostly at BGI (formerly Beijing Genomics Institute). and DNA samples prepared mostly at Duke. The budgerigar, a parrot, was sequenced at Duke. There are 29 papers in this first release, but many more will tumble out for years to come.

“In the past, people have been using 1, 2, up to 20 genes, to try to infer species relationships over the last 100 million years or so,” Jarvis says. But whole-genome analysis drew a somewhat different tree and yielded important new insights.

More than 200 researchers at 80 institutions dove into this sea of big data like so many cormorants and pelicans, coming up with new insights about how flight developed and was lost several times, how penguins learned to be cold and wet and fly underwater and how color vision and bright plumage co-evolved.

The birds’ genomes were found to be pared down to eliminate repetitive sequences of DNA, but yet to still hold microchromosomal structures that link them to the dinosaurs and crocodiles.

The sequencing of still more birds continues apace as the Jarvis lab at Duke does most of the sample preparation to turn specimens of bird flesh into purified DNA for whole-genome sequencing at BGI. (More after the movie!)


As one of three ring-leaders for this massive effort, Erich Jarvis is on 20 papers in this first set of findings. Eight of those concern the development of song learning and speech, but the other ones are pretty cool too:

Evidence for a single loss of mineralized teeth in the common avian ancestor. Robert W. Meredith, et al. Science. Instead of teeth, modern birds have a horny beak to grab and a muscular gizzard to “chew” their food. This analysis shows birds lost the use of five genes related to making enamel and dentin just once about 116 million years ago.

Complex evolutionary trajectories of sex chromosomes across bird taxa. Qi Zhou, et al. Science. The chromosomes that determine sex in birds, the W and the Z, have a very complex history and more active genes than had been expected. They may hold the secret to why some birds have wildly different male and female forms.

Three crocodilians genomes reveal ancestral patterns of evolution among archosaurs. Richard E Green, et al Science. Three members of the crocodile lineage were sequenced revealing ‘an exceptionally slow rate of genome evolution’ and a reconstruction of a partial genome of the common ancestor to all crocs, birds, and dinosaurs.

Evidence for GC-biased gene conversion as a driver of between-lineage differences in avian base composition. Claudia C. Weber, et al, Genome Biology. The substitution of the DNA basepairs G and C was found to be higher in the genomes of birds with large populations and shorter generations, confirming a theoretical prediction that GC content is affected by life history of a species.

Low frequency of paleoviral infiltration across the avian phylogeny. Jie Cui, et al. Genome Biology. Genomes maintain a partial record of the viruses an organism’s family has encountered through history. The researchers found that birds don’t hold as much of these leftover bits of viral genes as other animals. They conclude birds are either less susceptible to viral infection, or better at purging viral genes.

Genomic signatures of near-extinction and rebirth of the Crested Ibis and other endangered bird species. Shengbin Li, et al Genome Biology. Genomes of several bird species that are recovering from near-extinction show clues to the susceptibilities to climate change, agrochemicals and overhunting that put them in peril. This effort has created better information for improving conservation and breeding these species back to health.

Dynamic evolution of the alpha (α) and beta (β) keratins has accompanied integument diversification and the adaptation of birds into novel lifestyles. Matthew J. Greenwold, et al. BMC Evolutionary Biology.  Keratin, the structural protein that makes hair, fingernails and skin in mammals, also makes feathers. Beta-keratin genes have undergone widespread evolution to account for the many forms of feathers and claws among birds.

Comparative genomics reveals molecular features unique to the songbird lineage. Morgan Wirthlin, et al. BMC Genomics. Analysis of 48 complete bird genomes and 4 non-bird genomes identified 10 genes unique to the songbirds, which account for almost half of bird species today. Two of the genes are more active in the vocal learning centers of the songbird brain.

Reconstruction of gross avian genome structure, organization and evolution suggests that the chicken lineage most closely resembles the dinosaur avian ancestor. Michael N. Romanov, et al. BMC Biology. Of 21 bird species analyzed, the chicken lineage appears to have undergone the fewest changes compared to the dinosaur ancestor.

Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the cold aquatic environment. Cai Li, et al. Gigascience. The first penguins appeared 60 million years ago during a period of global warming. Comparisons of two Antarctic species show differences and commonalities in gene adaptations for extreme cold and underwater swimming.

Evolutionary genomics and adaptive evolution of the hedgehog gene family (SHH, IHH, and DHH) in vertebrates. Joana Pereira, et al. PLoS ONE. Whole-genome sequences for 45 bird species and 3 non-bird species allow a more detailed tracing of the evolutionary history of three genes important to embryo development.

A Duke lab led the effort to isolate bird DNA for sequencing at BGI: (L-R) Erich Jarvis, associate professor of neurobiology and Howard Hughes Medical Institute investigator, lab research analyst Carole Parent, undergraduate research assistant Nisarg Dabhi, and research scientist Jason Howard. (Duke Photo, Les Todd)

A Duke lab led the effort to isolate bird DNA for sequencing at BGI: (L-R) Erich Jarvis, associate professor of neurobiology and Howard Hughes Medical Institute investigator, lab research analyst Carole Parent, undergraduate research assistant Nisarg Dabhi, and research scientist Jason Howard. (Duke Photo, Les Todd)

How To Get Your Foot In The Door At A Research Lab

By: Thabit Pulak

So now you are at Duke — one of the world’s best research universities — but now what? You might be taking cool classes, but how can you take advantage of the world-class research happening here? Roughly 50 percent of Duke undergrads do so at some point. Getting involved in research as a freshman might sound intimidating (I know it did to me!), but a little luck and perseverance can get you off to a strong start.

Alan working in Dr. Eroglu's laboratory.

Alan working in Dr. Eroglu’s laboratory.

I had the opportunity to talk with Duke freshman Alan Kong about his experiences trying to get into research labs, and how he successfully ended up finding one to join. Alan is considering majoring in biology whilst on the premed track.

He initially started to look into labs within a month of  starting classes at Duke. He spent about two months sending out emails to professors who were working on interesting projects.

“It was a very frustrating search, and initially difficult. I emailed five professors, and emailed each many times,” Alan said. “But perseverance ultimately paid off.”

Alan now works in the lab of Dr. Eroglu who is an assistant professor of cell biology, associated with the Duke School of Medicine. According to the Duke Institute of Brain Science website description, Eroglu’s laboratory “is interested in understanding how central nervous system (CNS) synapses are formed.”

Alan was also accepted into two others labs, but ultimately felt Dr. Eroglu was the best fit. “I picked Eroglu because her research was very interesting, and relevant to my interests,” Alan says. “I felt I could learn more interesting techniques in research, such as working with live animals.”

Now, Alan has been working in Dr. Eroglu’s lab for a month. When I asked him how it was going, with a smile he exclaimed, “It’s great!”

“Right now I am learning techniques such as genotyping, western blot. I even took out the retina of a rat!” Alan said. “I am learning the ropes of the lab, and my mentor said that down the road, if I learn properly, I can eventually work on my own independent project!”

When asked for any advice for other students thinking of getting into research, Alan said “Persistence is key — don’t give up! It’s a difficult process; don’t let small things get in the way. Keep trying until you find one.”

Alan

“Persistence is key – don’t give up!” Alan says

Learn more:

More information regarding Dr. Eroglu and her research: http://www.dibs.duke.edu/research/profiles/46-agla-eroglu

List of all Duke Faculty affiliated with Cell Biology with contact details: http://www.cellbio.duke.edu/all-faculty/

Summer research opportunities in math and statistics: http://bigdata.duke.edu/research/?field_project_topics_tid=19

Research opportunities in biology: http://cubr.biology.duke.edu/projects

For other research and summer opportunities visit https://biology.duke.edu/undergraduate/current-students/research-independent-study/summer-opportunities

For a list of research opportunities across the sciences, arts, humanities and social sciences visit: http://undergraduateresearch.duke.edu/uploads/media_items/summer-2015-funding-opps.original.pdf

 

 

More Elephants Means Fewer Trees in Kruger National Park

By Duncan Dodson

Imagine learning research methods while also getting charged by a rhino, observing a pride of lions hunting warthogs, and glimpsing a cheetah and her cub.

Lizzie feeding an elephant in Kruger National Park in South Africa. Her research attempted to map woody tree coverage in a section of the park since rising elephant populations has resulted in the destruction of woody trees.

Lizzie feeding an elephant in Kruger National Park in South Africa. Her research attempted to map woody tree coverage in a section of the park since rising elephant populations has resulted in the destruction of woody trees.

Elizabeth “Lizzie” Hoerauf experienced this last summer with five other students from Yale, Vanderbilt, Duke, and Reed Universities. The Organization for Tropical Studies (OTS) brought them to Kruger National Park in South Africa, charging them with researching various plants and animals in the park — with a primary focus on the effects of the park’s growing elephant population.

Culling of elephants – i.e., reducing their populations by selective slaughter — has been banned since 1994, resulting in a significant increase in the elephant population. This seems admirable, yet as the increasingly abundant massive animals roam the savanna they knock down more trees. Fewer trees across the park means lower habitat diversity for the park’s other plants and animals.

Lizzie’s project laid the groundwork for other students’ surveying efforts. To map woody cover, Lizzie took overhead images from previous park data of one of the four supersites that make up the park and overlaid them using Geographic Information Systems (GIS) software.

Her project did not come without its struggles. One moment she would emerge from her tent with a look of triumph telling her peers, “Guys look how amazing this is!” The next, disgruntled and lamenting, “Everything crashed….” However, her ultimately successful data consolidation demonstrated that less than ten percent of the area she studied was now populated with tall trees — a significant decrease from years past.

With some time to reflect Lizzie says that she learned more from this project than in the classroom. When I asked her if she had interests in returning to project in the future she noted a preference to pursue field research projects of her own. Lizzie did let me know that OTS is a wonderful program that Duke offers — it felt rewarding to be a small part of a massive and constantly evolving field research project.

Using Geographic Information Systems (GIS) software, Lizzie was able to map out and analyze woody tree cover for one of the supersites of the park. Her analysis found approximately 6 percent of the supersite to be covered by tall trees, much lower than previous years (12 percent in 1940 or 9 percent in 1974).

Using Geographic Information Systems (GIS) software, Lizzie was able to map out and analyze woody tree cover for one of the supersites of the park. Her analysis found approximately 6 percent of the supersite to be covered by tall trees, much lower than previous years (12 percent in 1940 or 9 percent in 1974).

The Science of Self-Agency: Dr. Nicolelis and the Walk Again Project

By Olivia Zhu

Screen grab from Univision of Juliano's robo-kick at the World Cup opening ceremony.

Screen grab from Univision of Juliano’s robo-kick at the World Cup opening ceremony.

Over the course of his 20-year career, Dr. Miguel Nicolelis has restored movement and self-agency to paraplegic patients.

On November 11th, as part of the Grand Challenge Seminar Series, Dr. Nicolelis captivated his audience by explaining the extensive process that culminated in Juliano, a Brazilian 29-year-old paralyzed from the chest downward in a car accident, performing the opening kick of the World Cup simply by using his mind.

Dr. Nicolelis has several faculty appointments in the Duke School of Medicine, Department of Psychology and Neuroscience, Institute for Brain Sciences, and Center for Neuroengineering. He has also written a book, Beyond Boundaries, about his work. His program, Walk Again, is supported by the Edmond and Lily Safia International Institute of Neuroscience in Brazil.

Dr. Nicolelis began making progress in 1999-2000 at Duke by developing electrodes that could record firing from multiple neurons. Using this technology, he determined which neurons were necessary for a monkey to move a joystick during a video game. Then, Dr. Nicolelis focused on creating a bypass that would bridge the mind directly to a computer, essentially removing the body as an intermediary.

He called this bypass a “Brain-Machine Interface,” or BMI, a term he coined at a cheese steak joint outside of Philadelphia. With the BMI, Dr. Nicolelis’s monkeys could play the video game without moving their arms or the joystick—they simply imagined themselves moving the joystick. The monkeys could even use their arms to do other tasks like eat or scratch themselves, creating a “third arm.”

Since then, with an extensive team of engineers, Dr. Nicolelis has implemented this technology by creating a IMG_1941hydraulically-powered exoskeleton that interprets a patient’s firing neurons and moves a patient’s legs accordingly.

He has also created artificial “skin,” which provides tactile feedback of movement to a patient’s upper body or, eventually, through an implant directly to the tactile cortex of the brain.

The technology is so accurate that patients report feeling “ghost limbs”—they believe that their legs are actually walking. The legendary Brazilian soccer player, Ronaldo, reportedly exclaimed “I’m moving!” with incredulity, when he was strapped to a chair testing Nicolelis’s technology.

Training with the exoskeleton also improves patients’ cardiovascular circulation, mental health, gastrointestinal health, and sensitivity in previously paralyzed areas.

Dr. Nicolelis is truly using science to stretch the boundaries of the human body.

Scents Are Key to Lemur Nightlife

LEMUR SUPERPOWER #457:  Some lemurs can safely digest cyanide in amounts sufficient to kill an elephant. Others can enter hibernation-like states to survive periods when food and water are in short supply. To add to their list of superpowers, lemurs also have especially keen powers of scent.

Buried in the nose of Fuggles the mouse lemur are specialized pheromone receptors that help her distinguish friend from foe in the dark of night, when mouse lemurs are active.

By Robin Ann Smith

If you could pick one superpower, consider taking inspiration from lemurs. Some lemurs can safely digest cyanide in amounts that would kill an elephant. Others can enter hibernation-like states to survive periods when food and water are in short supply. Still others have keen powers of scent, with the ability to find mates and avoid enemies in the darkness by smell alone.

Research by biologist and Duke Lemur Center director Anne Yoder suggests that the molecular machinery for sniffing out pheromones — much of which has gone defunct in humans and many other primates — is still alive and well in lemurs and lorises, our distant primate cousins.

Lemurs use scents to mark the boundaries of their territories, distinguish males from females and figure out whether another animal is friend or foe. When a lemur gets a whiff of another animal, specialized pheromone receptors in the lining of the nose transmit the information to the brain, triggering instinctive urges like mating, defense and avoiding predators.

The receptors are proteins encoded by a family of genes called V1Rs. First identified in rats in the mid-1990s, V1R genes are found in animals ranging from lampreys to humans. But the proportion of these pheromone-detection genes that actually functions varies greatly from one species to the next, Yoder said last week in a roundtable discussion hosted by Duke’s Science & Society program.

Randy the ring-tailed lemur scent-marks his territory. Photo by David Haring.

Randy the ring-tailed lemur scent-marks his territory. Photo by David Haring.

Studies suggest that as much as 90% to 100% of the pheromone-detection genes in humans consist of disabled pieces of DNA, called pseudogenes.

“Our pheromone-detection genes are so boring — we don’t have many of them, and almost all of them are broken,” Yoder said.

But in lemurs and lorises — whose ancestors split off from the rest of the primate family tree more than 60 million years ago — the proportion of pheromone-detection genes that is still intact is much higher.

In a study published this year, Yoder and colleagues analyzed the DNA of 19 species and subspecies of lemurs and lorises, looking for subtle differences in their V1R genes. They found that one group — the mouse lemurs — has the highest proportion of intact V1R sequences of any mammal yet studied.

To find out which genes are linked to which scents, Yoder and her colleagues plan to take DNA sequences from pheromone-detecting genes in lemurs, insert them into mice, and expose the mice to different scents to see how they respond.

An ability to sniff out the right mates — and avoid being seduced by the wrong suitors — may have served as a mating barrier that allowed lemur species to diverge after arriving in their island home of Madagascar, helping to explain how the more than 70 living species of lemurs came to be, Yoder says.

The Mystery Behind the Camel Statue

Knut Schmidt-Nielsen

A file photo of the real Knut Schmidt-Nielsen, not the bronze one, standing with the enigmatic camel statue dedicated to him and his work.

By Olivia Zhu           

The camel statue between the Biology Building and Gross Hall is a staple of Duke’s campus, but the significance behind this landmark is generally unknown.

On Monday, September 22, faculty from the Biology Department gathered for a dedication to remember the man behind the camel statue (or rather, in front of it), Dr. Knut Schmidt-Nielsen, who died in 2007.

Knut Schmidt-Nielsen, who would have turned 99 this Wednesday, was “the father of comparative physiology and integrative biology” and a James B. Duke professor at Duke’s Biology Department starting in 1952.

Schmidt-Nielsen studied the physiology of the camel’s nose, received the International Prize for Biology, and wrote the authoritative text on animal physiology.

Dr. Stephen Wainwright, who was present at the dedication, commissioned the camel to British sculptor Jonathan Kingdon, who finished the bronze camel statue in 1993. The inscription for the statue, “Tell me about yourself, Camel, that I may know myself,” encapsulates Schmidt-Nielsen’s outlook on physiology.

According to Dr. Steven Vogel, who was recruited to Duke’s faculty by Schmidt-Nielsen 49 years ago, Schmidt-Nielsen was actually shy and rather uncomfortable with the statue of himself. Vogel reported that Schmidt-Nielsen greatly advanced the zoology department with his high standards and “great charm and urbanity.”

“You could never say no to Knut,” Vogel said. Schmidt-Nielsen was also reportedly  “a very serious wine drinker”—accordingly, the dedication ceremony ended with wine and champagne.

To learn more about Knut Schmidt-Nielsen, read Vogel’s memoirs or a recommended autobiography, The Camel’s Nose.

Knut Schmidt-Nielsen

The statue as it appears now, with Knut in bronze. (File photo)