Charles F. Baer, Ph.D.
Department of Biology
University of Florida Genetics Institute
Abstract
Understanding the relative contributions of the different evolutionary forces to phenotypic evolution is a central mission of population and quantitative genetics. As a starting point, it is important to isolate the contributions of mutation from the other forces, because mutation can never be "turned off". A Mutation Accumulation (MA) experiment provides a way to quantify the cumulative effects of mutation in the (near) absence of natural selection. Then, comparison of the properties of genetic variation introduced by mutation to those of the standing genetic variation within and/or between populations provides insight into what natural selection does or does not want.
We use data from a set of C. elegans MA lines to address two fundamental questions in evolution. First, we quantify the amount of mutational input into the mutational process itself. We find that the genome-wide mutation rate evolves significantly upward over a few hundred generations of relaxed natural selection. Second, we compare two independent measures of selection acting on new spontaneous mutations, one of which is conceptually airtight but of limited utility, the other of which is conceptually suspect but of broad utility (and widely applied). Happily (or coincidentally), the two measures agree with within a factor of two. We further show that new spontaneous mutations interact synergistically, potentially explaining why we have not Died 100 Times Over. Finally, we show that the base-substitution spectrum of experimentally accumulated mutations differs significantly from the spectrum of standing rare variants. That discrepancy means either (a) that natural selection skews the spectrum, or (b) mutations accumulated in the lab do not faithfully reflect the natural spectrum. We increasingly suspect the latter.
Host: Soojin Yi, Ph.D.
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Host: Francesca Storici
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Turgay Akay, PhD
Department of Medical Neuroscience
Dalhousie University
Abstract
To generate locomotor behavior, the nervous system must precisely regulate the timing and the strength (locomotor pattern) of multiple flexor and extensor muscle contractions controlling movement at the three joints of the hindlimb. These locomotor patterns are generated by the combined actions of a network of interconnected interneurons within the spinal cord (the central pattern generator) and sensory feedback from the periphery, but how these two components are integrated and collectively act to control movement remain obscure. Using an interdisciplinary approach including mouse genetics, in vivo electrophysiology, motion analysis, and computational methods, I will discuss recent findings in my laboratory addressing the role of proprioceptive sensory feedback in locomotor pattern generation.
About the Speaker
Turgay Akay completed an undergraduate degree in fisheries engineering at Süleyman Demirel University in Turkey. His interest in animal behaviour led him back to Germany, where he was born, to pursue a diploma degree in biology at the University of Bielefeld and a PhD at the University of Cologne’s Institute for Zoology. His PhD thesis addressed the role of sensory feedback in interjoint coordination in insect walking. Upon completing his PhD in 2002, Dr. Akay re-located to North America. Following postdoctoral stints at the University of Pennsylvania with Dr. Michael Nusbaum and University of Alberta with Dr. Keir Pearson, Dr. Akay made the move to Columbia University, where he worked with Dr. Tom Jessell and later became an associate research scientist at Columbia’s Center for Motor Neuron Biology and Disease. Already a long-time collaborator with Dalhousie’s motor neuron researchers, Dr. Akay made the move to Halifax in 2014 to join the Department of Medical Neuroscience as an Assistant Professor.
Physiology Brownbag Seminars
The Physiology Group in the School of Biological Sciences hosts Brownbag Lunchtime Seminars twice a month on Wednesdays at noon in room 1253 of the Applied Physiology Building located at 555 14th Street NW, Atlanta, GA 30318. You are welcome to bring a lunch and join us as we ruminate with us on topics in Physiology! A full listing of seminars can be found at http://pwp.gatech.edu/bmmc/physiology-brownbag-seminars-spring-2019/.
Host: Boris I. Prilutsky, Ph.D.
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Struck by climbing suicide rates, third-year School of Biological Sciences major Collin Spencer organized the first Intercollegiate Mental Health Conference, which kicked off on Feb. 15, 2019. "Mental health is one of the most pressing issues for adolescents in the country right now," Spencer says.
Bulking up to avoid being eaten may have been one reason single-celled organisms joined to form multicellular entities. That’s one of the hypotheses to explain the transition to multicellularity in the early stages of life on Earth. How and why that transition occurred is one of the major questions in the story of how life began and evolved.
Georgia Tech researchers report evidence to support this hypothesis. Watching in real time, they observed how a single-celled alga became a multicellular organism in just 50 weeks after they introduced a predator. The study was published online on Feb. 20, 2019, in Scientific Reports.
“The study showed that small single-celled organisms can evolve to become larger multicellular organisms as a way to avoid being eaten,” says Matt Herron, a senior research scientist in the School of Biological Sciences and the study’s lead author.
“Nearly every living thing has to contend with the possibility of being a meal to others,” Herron says. Complex life forms have evolved various defenses to avoid becoming someone else's dinner – such as camouflage, speed, weapons, and chemical defenses. One way to avoid being eaten is to become too big for the predators. Among microbes, one way to get bigger is to form a group of cells – in other words, to become multicellular.
All multicellular organisms evolved from unicellular ancestors. But because the evolution occurred hundreds of millions of years ago, it’s hard to know how or why it happened. Experimental evolution allows researchers to watch evolutionary change as it occurs in real time in the laboratory.
“We grew some algae with predators and some without predators,” says William Ratcliff, an assistant professor in the School of Biological Sciences and study coauthor. “After 50 weeks, we compared the two cultures. We found that some cultures grown with predators had become multicellular, but cultures grown without predators remained unicellular.”
“This could be a first step toward the kind of complex multicellularity we see in animals, plants, fungi, and seaweeds,” Herron says. “The multicellular algae that evolved in our experiment could be used to explore how they continue to evolve. For example, can these algae evolve a division of labor, with cells becoming specialized to perform different functions?”
Other authors from Georgia Tech are School of Biological Sciences Professor Frank Rosenzweig, postdoctoral researcher Kimberly Chen, technician Joshua Borin, and graduate students Jacob Boswell and Jillian Walker. Other coauthors are Charles Knox and Margarethe Boyd, of the University of Montana, Missoula.
This work was supported by the National Science Foundation, NASA, the Packard Foundation, and the John Templeton Foundation.
Figure Caption
Depiction of algal life cycles after evolution with (B, C, and D) or without (A) predators for 50 weeks. D shows a fully multicellular life cycle, with multicellular clusters releasing multicellular propagules. (Credit: Scientific Reports)
By Brent Verrill, Communications Manager, Brent Byer Institute for Sustainable Systems
Twenty-three Georgia Tech undergraduate students have been selected for the second class of Sustainable Undergraduate Research Fellows (SURF). Among them are Kathryn McCarthy, School of Biological Sciences; Shivan Mittal, School of Physics; and Gigi Pavur, School of Earth and Atmospheric Sciences.
McCarthy and Mittal are among the 20 new fellows. Pavur is among the three who are returning from the previous year of the program.
The fellows represent all six colleges at Georgia Tech and were selected from a highly qualified and competitive field of students.
- William Abdallah, Industrial Engineering
- Joseph Buehler, Chemical and Biomolecular Engineering
- Leo Chen (returning), Computer Science
- Anielle Duritza, Environmental Engineering
- Kian Halim (returning), Computational Media
- Kyte Harvey, Mechanical Engineering
- Connor Hawley, Electrical Engineering and Computer Science
- Chloe Kiernicki, Architecture
- Elizabeth Krakovski, Public Policy
- Micah Landwermeyer, Materials Science and Engineering
- Matthew Lim, Computer Engineering
- Farouk Marhaba, Computer Science
- Kat Matthews, Business
- Kathryn McCarthy, Biological Sciences
- Shivan Mittal, Physics
- Christi Nakajima, Public Policy
- Gigi Pavur (returning), Earth and Atmospheric Sciences
- Leah Claire Nofsinger, Materials Science and Engineering
- Ashlyn Sasser, Industrial Design
- Alexandra Schultz, Chemical Engineering
- Ranal Apeksha Tudawe, Mechanical Engineering
- Jeniveve Vaia, Material Science and Engineering
- Eliya Olivia Wagner, Environmental Engineering
The research fellows, who are paid, are developing prototypes of interactive building-monitoring systems that convey the unique elements, qualities, and performance of the Kendeda Building for Innovative Sustainable Design, which is under construction. The systems will also monitor the behaviors that the buiding engenders among its occupants and visitors.
Through SURF, the students will learn about sustainability, systems thinking, and how to apply these principles to the Georgia Tech Living Building. Their work is facilitated by Michael Chang, deputy director of the Brook Byers Institute for Sustainable Systems.
As a building coordinator for the School of Biological Sciences, Lyubomir “Lyubo” Lichev takes care of the facility, but more importantly, he takes care of people.
Every workday is different, he said, but each begins at 7 a.m. with a walk through the Cherry Emerson Building to ensure everything is in place from the previous night and ready for the new day.
“Building Coordinator 1 is a very diverse job,” Lichev said. “I handle small things like issuing keys to lab members and putting fuel into the vehicles, to bigger projects like taking inventory of equipment and handling the disposal of old equipment.”
He said he likes helping professors fill their day-to-day needs in the lab, and it’s a rewarding feeling to know that he made someone’s day brighter. He also likes interacting with new people as he does his work.
“The School of Biological Sciences is a big school, so I meet new faces every day,” said Lichev, who is also an industrial and systems engineering Tech student. “It makes an interesting conversation when I meet classmates outside the classroom while working.”
Lichev grew up in Bulgaria and earned a bachelor’s degree in manufacturing engineering from the Technical University of Sofia in 2008. He moved to the United States 10 years ago at age 22, leaving his entire family in Bulgaria. Only three of his classes from Bulgaria were transferable to the U.S., so he effectively had to start college again. In 2017, he earned an associate’s degree in engineering from Georgia State University – Perimeter College. He’s currently a part-time Tech student in his third year.
“The industrial engineering degree I’m pursuing at Tech is a natural follow-up to the manufacturing degree I earned in Bulgaria,” he said. “To me, the industrial engineering degree here shows how a business runs and how we can make it run better. It is very versatile and is the right one for me. I want to see it through.”
Lichev said that after graduating he would like to keep working at Georgia Tech, perhaps as an in-house consultant who examines a unit and identifies ways to help it work more efficiently.
“I know I’m a few years from graduation, and things change,” he said, “but I can see myself retiring from the Institute.”
Lichev said he enjoys being an employee and a student, and he encourages others to do the same through the Tuition Assistance Program.
“I would like to see more of my colleagues take classes,” he said. “It doesn’t have to be at Georgia Tech. As long as the school is in the University System of Georgia, they can access the benefits.”
Away from Work
Lichev’s job, classes, and homework leave him with little time for hobbies.
“When I’m not working or doing schoolwork, the thing I enjoy best is sleep. I know a lot of Tech students can relate to that,” he said. “After graduation, I will develop some hobbies. For now, sleep is my best friend.”
He keeps in touch with his family in Bulgaria through weekly video chats. He said that because of the seven-hour time difference, finding a good time for everyone to talk can be tricky.
His most recent trip to Bulgaria was Christmas 2018. Before then, he hadn’t been there since 2014 when he made a surprise visit on his father’s 50th birthday.
“I’m not going to wait another four years before I go back,” he said. “If I can, I’ll go back this year.”
The 2019 Karlovitz Lecture and a Frontiers in Science Lecture to celebrate 2019, the International Year of the Periodic Table
The 2019 Karlovitz Lecture will be delivered by best-selling author Sam Kean.
Kean's book about the periodic table, "The Disappearing Spoon," answers many uncommon questions about chemical elements: Why did Gandhi hate iodine? Why did the Japanese kill Godzilla with missiles made of cadmium? How did radium nearly ruin Marie Curie’s reputation? And why did tellurium lead to the most bizarre gold rush in history?
According to Kean, the periodic table is one of humanity’s crowning scientific achievements, but it’s also a treasure trove of passion, adventure, betrayal, and obsession.
About the Speaker
Best-selling author Sam Kean’s book “The Disappearing Spoon” delves into every element in the periodic table and explains each one’s role in science, money, mythology, war, the arts, medicine, alchemy, and other areas of human history, from the Big Bang through the end of time.
In addition to “The Disappearing Spoon,” Sam Kean has several other titles on the New York Times bestselling list: “Caesar’s Last Breath,” “The Dueling Neurosurgeons,” and “The Violinist’s Thumb.” All of his books were named Amazon top science books of the year. His work has been featured on NPR’s “Radiolab,” “All Things Considered,” and “Fresh Air.”
Sam Kean will sign books after the lecture.
About the Karlovitz Lecture
The lecture is made possible by an endowment in memory of College of Sciences Dean Les Karlovitz, who served as dean for 16 years until 1989. Seeking to broaden intellectual discourse on campus, the series focuses on speakers whose work has led them to stretch across disciplinary boundaries.
About Frontiers in Science Lectures
Lectures in this series are intended to inform, engage, and inspire students, faculty, staff, and the public on developments, breakthroughs, and topics of general interest in the sciences and mathematics. Lecturers tailor their talks for nonexpert audiences.
About the Periodic Table Frontiers in Science Lecture Series
Throughout 2019, the College of Sciences will bring prominent researchers from Georgia Tech and beyond to expound on little-discussed aspects of chemical elements:
- Feb. 6, James Sowell, How the Universe Made the Elements in the Periodic Table
- March 5, Michael Filler, Celebrating Silicon: Its Success, Hidden History, and Next Act
- April 2, John Baez, University of California, Riverside, Mathematical Mysteries of the Periodic Table
- April 18, Sam Kean, Author, The Periodic Table: A Treasure Trove of Passion, Adventure, Betrayal, and Obsession
- Sept. 12, Monica Halka, The Elusive End of the Periodic Table: Why Chase It
- October 31, Taka Ito, Turning Sour, Bloated, and Out of Breath: Ocean Chemistry under Global Warming
- Nov. 12, Margaret Kosal, The Geopolitics of Rare and Not-So-Rare Elements
Closest visitor parking is Area 6 (Fifth Street and Spring) or Area 8 (Tech Square) on the parking map, https://pts.gatech.edu/visitors#l3.
Event Details
Have you ever wondered what it’s like to be a faculty member at a small undergraduate focused liberal arts college? This job is a great option if you’re passionate about teaching and working with undergraduates on your research projects. At this info session, three STEM faculty members working at Harvey Mudd College will give you a feel for the day-to-day life as a faculty member at this kind of institution. We’ll have lots of time for Q and A, so please bring lots of questions! RSVP here or at https://goo.gl/forms/Pyu0ty7qvCxrW98y2 to make sure you get fed!
ABOUT THE SPEARKERS
Jason Gallicchio
Assistant Professor of Physics
https://www.hmc.edu/about-hmc/hmc-experts/gallicchio-jason/
Jason specializes in experimental cosmology—the study of the origin and evolution of the universe. Gallichio spent a year at the South Pole Telescope where he researched polarization of the Cosmic Microwave Background (CMB) and served as a South Pole NSF Station Science Leader. He is also interested in devising new ways to conduct fundamental tests of quantum mechanics and has designed improvements for Bell-type tests of quantum entanglement.
Danae Schulz
Assistant Professor of Biology
https://www.hmc.edu/biology/faculty-staff/danae-schulz/
Danae studies the African trypanosome, a protozoan parasite that causes sleeping sickness in humans and nagana in cattle. Trypanosomes are transmitted to the bloodstream of a mammal through the bite of a tsetse fly, eventually leading to coma and death. Danae would like to understand what allows trypanosomes to reprogram themselves to adapt as they move between the differing environments of the fly midgut and the mammalian bloodstream, with an eye toward trying to manipulate these adaptations to generate new therapies.
Brian Shuve
Assistant Professor of Physics
https://www.hmc.edu/about-hmc/hmc-experts/shuve-brian/
Brian researches theoretical particle physics. Shuve develops and studies new theories to explain mysteries of the universe, such as the nature of dark matter and why there exists more matter than antimatter. He also devises and implements new experimental tests to learn more about the fundamental constituents and forces of matter. For example, Shuve researches how the discovery of new particles at high-energy colliders such as CERN’s Large Hadron Collider could shed light on the physical processes taking place in the early universe that shape the world as we see it today.
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Alain Frigon, Ph.D.
Department of Pharmacology-Physiology
Université de Sherbrooke
Abstract
After complete spinal cord injury (SCI), adult cats recover hindlimb locomotion after a few weeks of treadmill training. This recovery is due to the presence of a spinal locomotor central pattern generator (CPG), which is thought to be reactivated by sensory feedback from the moving legs. One of the central tenets of motor rehabilitation is that training must be task specific. However, as the locomotor CPG is present at birth, we hypothesized that task-specific training is not required to restore locomotion after complete SCI. To test this hypothesis, we investigated whether providing non-task-specific training in the form of rhythmic manual stimulation of the triceps surae muscles restored hindlimb locomotion after complete SCI in cats. Twelve adult cats (>10 months) were divided into three groups and implanted with electrodes to chronically record muscle activity (EMG, electromyography). After collecting data in the intact state, we transected the spinal cord at low thoracic levels. Group 1 received rhythmic manual stimulation of the triceps surae muscles, Group 2 received traditional treadmill training while Group 3 received no treatment. Cats in all three groups recovered full body weight support during standing one week after SCI. Six weeks after SCI, cats in all groups performed full weight bearing hindlimb locomotion from 0.1 to 0.8 m/s. The results indicate that the recovery of hindlimb locomotion after complete SCI does not require task-specific training and is partly spontaneous, consistent with the hypothesis that the spinal cord produces locomotion as its default pattern.
More about the Speaker
Dr. Alain Frigon has a broad background in neuroscience and kinesiology, with specific expertise in spinal cord neurophysiology and locomotor control. For the past 15 years, his research has focused on the neural control of rhythmic movements (arm cycling, locomotion and scratching) and on neurophysiological changes that take place after spinal cord or peripheral nerve injury. He received experimental training in motor control in humans (E. Paul Zehr) and with the cat model in three different laboratories that use complementary preparations, including in vivo recordings in awake behaving cats (Serge Rossignol), intracellular/extracellular recordings in curarized decerebrate cats (Jean-Pierre Gossard) and electromyography and force recordings in immobilized decerebrate cats (Charles J. Heckman). His lab currently uses a range of experimental techniques to study the control of movement in the cat and is funded by the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada.
Physiology Brownbag Seminars
The Physiology Group in the School of Biological Sciences hosts Brownbag Lunchtime Seminars twice a month on Wednesdays at noon in room 1253 of the Applied Physiology Building located at 555 14th Street NW, Atlanta, GA 30318. You are welcome to bring a lunch and join us as we ruminate with us on topics in Physiology! A full listing of seminars can be found at http://pwp.gatech.edu/bmmc/physiology-brownbag-seminars-spring-2019/.
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