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Biology Seminar: Postdoc Minisymposium

Mackenzie G., Elli T., Vivek S., Timothy G.
University of Washington, Department of Biology
Seminar date:
Wednesday, October 24, 2018 - 12:00
HCK 132
Name: Mackenzie Gerringer
Lab: Adam Summers
Title: Life in the trenches: the biology of the planet's deepest-living fishes
The hadal zone, depths 6,000-11,000 m, is characterized by high pressures, low temperatures, far from sunlight and named after the proverbial hell. Yet, a host of organisms are adapted to survive and thrive in this extreme environment. The snailfishes, family Liparidae (Scorpaeniformes), have found notable success in the hadal zone from depths ~6,000–8,200 m. The hadal fish community is distinct from the surrounding abyss where solitary, scavenging fishes such as rattails (Macrouridae), cutthroat eels (Synaphobranchidae), eelpouts (Zoarcidae), and cusk eels (Ophidiidae) are most common. Little is known about the biology of these deepest-living fishes, nor the factors that drive their success at hadal depths. This seminar addresses the role of feeding ecology, pressure adaptation, and life history in structuring fish communities at the abyssal-hadal boundary. These studies provide insight into the ecology and physiology of deep-dwelling fishes and inform new understanding of life in the trenches. 
Mackenzie Gerringer's research centers on the physiology and ecology of deep-sea animals, especially in the hadal zone, depths 6000 - 11,000 m. She earned her PhD in Marine Biology from the University of Hawaii in 2017 and is currently a postdoctoral researcher at Friday Harbor Labs, where she teaches, CT scans, mentors undergraduates, and 3D-prints fish parts. 

Name: Elli Theobald
Lab: Scott Freeman
Title: Weeding out diversity? 15 years of retrospective data and a meta-analysis of student achievement
Despite widespread effort to increase access to and diversity in STEM, women and minority students remain underrepresented in both STEM majors and STEM professions. Achievement gaps in college (i.e., differential performance between represented and under-represented students) likely contribute to this problem because lower performing students are more likely to drop out and less likely to major in STEM fields. Using two sources of evidence, we tested the hypothesis that active learning can close achievement gaps for historically under-represented students: First, we used retrospective data from the University of Washington to quantify achievement gaps in a predominantly lecture-based STEM curriculum. Then, we meta-analyzed instances of active learning closing achievement gaps for underrepresented students. We find 1) that achievement gaps in a lecture-based curriculum at UW are large and have serious consequences for students remaining in STEM, and 2) that on average, active learning narrows the achievement gap by nearly 50%.
Elli obtained her PhD in Janneke Hille Ris Lambers lab, here at UW, studying the effects of climate on plant and pollinator communities at Mount Rainier. She joined the BERG group in 2016, first working with Alison Crowe investigating equity in groupwork, and now working with Scott Freeman investigating systematic approaches to narrowing achievement gaps in STEM.

Name: Vivek Srinivas
Lab: Baliga lab, Institute for Systems Biology
Title: Characterization and elimination of translationally dormant persister subpopulation in mycobacteria
The ability of Mycobacterium tuberculosis (MTB) to tolerate antimicrobial killing is considered the major reason why a quarter of all patients require 6 months of treatment and an additional 5% are not cured even then. In order to shorten drug treatment and improve treatment outcome, it is necessary to first characterize and disrupt the mechanisms of antimicrobial tolerance (AMT) that precedes selection of resistance mutations. Here, we report a novel technology Per-Sort to identify and sort miniscule numbers of translationally dormant mycobacterial cells within an isogenic population of cells. Using Per-Sort we show that this pre-existing translationally dormant phenotype is nonheritable, and that the subpopulation is small in size, metabolically dormant, tolerant to antimicrobials, and expands in number upon nutrient starvation. Finally, measuring gene expression in single mycobacteria, we find that pre-existing persisters are a heterogeneous mix of vapC, mazF, and relA/spoT overexpressing cells that are eliminated and sensitized to antimicrobial killing through L-cysteine-mediated induction of metabolism.
Vivek obtained his PhD in Swati Patankar’s lab at Indian Institute of Technology Bombay, Mumbai, India studying the mechanisms in the translation regulation in asexual blood stages of malaria parasite Plasmodium falciparum. He joined the Baliga lab in 2016 to characterize the antimicrobial tolerance in Mycobacterium tuberculosis and discover novel drug regimens to reduce treatment durations of tuberculosis. 

Name: Timothy Gallaher
Lab: Caroline Stromberg
Title: Phytoliths, macrofossils and the early biogeographical history of the grass family
The timing of the origin and diversification of the grass family has become the subject of robust debate. Phylogenetic calibration using fossils from outside the family provide a much younger timeframe than do fossils, particularly phytoliths, from within the family. Using new phytolith identification tools and phylogenetic inference using both grass macrofossils and phytoliths we infer an Early Cretaceous Gondwanan origin of the Poaceae. Ancestral habitat reconstruction suggests that grasses first evolved in forest-associated habitats and that forest margins may have played an important role in allowing lineages to more readily transition into either deep shade or open habitats. In the Late Cretaceous through the Paleocene, several lineages began moving into open habitats, long before the spread of grass-dominated ecosystems in the Oligocene-Miocene. Our temporal reconstruction also indicates that C4 photosynthesis may have first evolved in the Early Eocene long before the rise to dominance of C4 grasslands in the last 10 million years. 
Timothy Gallaher earned his PhD. at the University of Hawaii where he studied the phylogenetics, biogeography and ethnobotany of the Screwpine family. Before coming to UW he worked in Lynn Clark’s lab at Iowa State University on grass leaf and cell form and function. For the past two years Tim has worked in Caroline Stromberg’s lab to quantify phytolith 3D shape and develop identification tools that will assist paleontologists with phytolith identification.
Fields of interest: