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Department of Biology Seminar

"Phased, Secondary siRNAs in Plant Reproduction and Other Pathways"

SelfieDr. Blake Meyers | Meyers Lab

BIO: 

Blake Meyers is a Member & Principal Investigator at the Donald Danforth Plant Science Center in St.

Louis, and he is a Professor in the Division of Plant Science and Technology at the University of

Missouri - Columbia. He formerly held the Edward F. and Elizabeth Goodman Rosenberg

professorship at the University of Delaware, where his research group was from 2002 to 2015. He

was elected as a Fellow of the American Association for the Advancement of Science (AAAS) in 2012,

and a Fellow of the American Society of Plant Biologists (ASPB) in 2017, the same year he was

awarded the Charles Albert Shull Award by the ASPB for outstanding investigations in the field of

plant biology. He was elected to the US National Academy of Sciences in 2022. After serving on the

editorial board since 2008, Blake became the Editor-in-Chief of The Plant Cell in January 2020. Work

in his lab addresses the biological functions, biogenesis, genomic impact, and evolution of small

RNAs in diverse plant species, using combination of genomic and molecular genetics approaches,

with a focus on phased, secondary siRNAs (“phasiRNAs”).



He received his undergraduate degree in biology from the University of Chicago in 1992, and

working with Prof. Richard Michelmore at UC Davis, was awarded M.S. and Ph.D. degrees in genetics in 1995 and 1998, respectively. After that, he did a postdoc with Prof. Michele Morgante at DuPont Crop Genetics, working on maize genomics for 2 years before returning to Prof. Michelmore’s group at UC Davis in 2000 to do a 2nd postdoc on Arabidopsis disease resistance. In 2002, Blake started his

own research group at the University of Delaware. He was the chair of the Department of Plant & Soil Sciences at the University of Delaware from 2009 to 2015.

Abstract:

In plants, 21 or 22-nt miRNAs or siRNAs typically negatively regulate target genes through mRNA cleavage or translational inhibition. Heterochromatic or Pol IV are 24-nt and function to maintain heterochromatin and silence transposons. Phased “secondary” siRNAs (phasiRNAs) are generated from mRNAs targeted by a typically 22-nt “trigger” miRNA, and are produced as either 21- or 24-mers via distinct pathways. Our prior work in maize and rice demonstrated the temporal and spatial distribution of two sets of “reproductive phasiRNAs”, which are extraordinarily enriched in the male germline of the grasses. These two sets are the 21-nt (pre-meiotic) and 24-nt (meiotic) siRNAs. Both classes are produced from long, non-coding RNAs, generated by hundreds to thousands of loci, depending on the species. These phased siRNAs show striking similarity to mammalian piRNAs in terms of their abundance, distribution, distinctive staging, and timing of accumulation, but they have independent evolutionary origins. The functions for these small RNAs in plants remain poorly characterized. I will describe our recent work investigating the functions of plant phasiRNAs and their roles in modulating traits of agronomic importance in plants, including male fertility, as well as novel applications of phasiRNAs such as those generated from transplastomic plants.

 

Date:
Location:
Plant Science Building-Cameron Williams Auditorium

"Cells and Molecules for Touch, Pain and Interoception"

Dr. Alexander Chesler | Chesler Lab

Chesler
Bio
Dr. Chesler received his degrees from Bard College (B.A., 1995) and Columbia University (Ph.D., 2005). His graduate study, in the laboratory of Dr. Stuart Firestein, was focused on the function and development of olfactory sensory neurons. He did his postdoctoral training in the laboratory of Dr. David Julius at the University of California, San Francisco, where he combined physiological, anatomical, and behavioral approaches to study the pharmacology of somatosensory neurons. He joined the NIH intramural pain program (NCCIH) in 2013 where his laboratory now employs multidisciplinary approaches to study how sensory stimuli (such temperature, touch, and environmental irritants) are detected and encoded by the somatosensory system.

Watch the seminar here!

Date:
Location:
THM 116

"Leveraging Animal Behavioral Interactions to Learn About Cognition & Social Dynamics"

Selfie

 

 

Dr. Elizabeth Hobson | Hobson Lab

Bio
Dr. Hobson received her PhD from New Mexico State University and was awarded two independent postdoctoral fellowships, the first at NIMBioS (the National Institute for Mathematical and Biological Synthesis) and the second at the Santa Fe Institute. She started her lab at the University of Cincinnati in Fall 2019 and is currently an Assistant Professor.

Abstract:
In many social species individuals create their social worlds through interaction decisions and are then subject to and constrained by these social constructs, which can affect an individual’s future actions. Understanding how much individuals “know” about their social worlds is critical in understanding these potential feedbacks. However, it is difficult to determine how much information individuals have about the social structures in which they live. In this talk, I summarize several ways my group is addressing these questions by combining empirical experiments with computational approaches to provide insight into cognition through social decisions. I highlight new work on parakeet aggression and dominance hierarchies to illustrate this approach. I show evidence that parakeet rank is unlikely due to individual characteristics and that group-level social dominance patterns can be plastic and can respond to group membership changes. Finally, I show how parallel or related experiments can allow for comparative analyses across species. These approaches, and a taxonomically broad perspective, provide new opportunities to investigate the effect of social information on individual behavior within conflict, and has the potential to provide rigorous evidence for the evolutionary patterns underlying social cognition.

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Date:
Location:
THM 116

"Overwintering in the Arctic: Animal Strategies for Surviving the Long, Cold, and Dark"

SelfieDr. Brian Barnes

Bio:
Dr. Barnes is currently a Professor of Zoophysiology with the Institute of Arctic Biology at the University of Alaska in Fairbanks. He's also the Director of Alaska INBRE, an NIH capacity building program in biomedical research and also the Science co-Director at Toolik Field Station. He participated in summer workshops involving biological rhythms at Hopkins Marine Station. He has a  PhD in Zoology from the University of Washington where Jim Kenagy was his advisor. Dr. Barnes received his Post-doc in Psychology and Zoology with Irv Zucker and Paul Licht as advisors. He began as Assistant Professor at the University of Alaska in 1986.

Abstract:
In Alaska, winters begin early, last seemingly forever, are very cold, snowy and dark, as well as extremely beautiful, quiet, and serene. This talk will review the physiological and behavioral strategies available to animals for surviving and coping with arctic winters, including cryobiology in insects, freeze tolerance in frogs, and hibernation in ground squirrels and bears. Using data logging and advanced telemetry, the locations, behavior, sleep, circadian rhythms, cardiovascular patterns, and thermoregulation of animals were recorded as they overwinter under natural conditions.

Cucujus beetle larvae may not freeze at temperatures below -80C, wood frogs freeze almost solid and survive; arctic ground squirrels lose track of time, become torpid while colder than ice but warm to sleep, even as black bears continuously doze, only occasionally snore, and their hearts beat in a syncopated rhythm. Little is known about the genetic and molecular basis of hibernation, but discovering its mechanisms could lead to novel clinical therapies and escape strategies in humans.

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Date:
Location:
THM 116

"Highlights from 57 Years of Studying the Ecology, Biogeography and Evolution of Seed Dormancy and Germination"

SelfieDr. Carol Baskin 

Abstract:
What controls the timing of seed germination in nature? This question is of much interest because the timing of seed dormancy-break and germination are an important part of the adaptation of a species to its habitat. Thus, we want to know what environmental conditions are required for seed dormancy-break and germination in various kinds of habitats from the tropics to the arctic, i.e. germination ecology.

My first germination experiments were conducted in 1966 when I was a graduate student at Vanderbilt University; I am still expanding my knowledge about seeds of wild plants. My original work/interests have expanded from germination ecology to the world biogeography of nondormancy and of the five classes/kinds of dormancy and to the evolutionary relationships of nondormancy and the classes of dormancy.

I have studied ca. 400 species from Kentucky/Tennessee, as well as species from Hawaii, Tiawan and Sweden. With collaborators, I have been involved in seed germination studies in Argentina, Australia, Brazil, China, India, Iran and Japan. The world biogeography of seed dormancy was part of a book entitled “Seeds: ecology, biogeography, and evolution of dormancy and germination, C.C. Baskin and J.M. Baskin, 1998 (1st ed.) 2014 (2nd ed.), Elsevier/Academic Press,” which contained a complication of data on the world biogeography of seed dormancy for ca. 3,000 (1st ed.) and 13, 600 (2nd ed.) species. This data set provides an overview of seed dormancy of trees, shrubs and herbs in all the major vegetation zones on earth, and it has now been used by various collaborators to help investigate other aspects of seed biology, including the evolution of seed dormancy (i.e. dormancy transition states).  

I am a plant ecologist, and as such I seek information about the fossils and palaeohistory of seeds, embryo morphology, dormancy-breaking and germination requirements of seeds of species in all the major vegetation zones on earth and evolutionary relationships of nondormancy and the five classes of dormancy. Recently, I have been exploring how palaeohistory, biogeography and phylogeny have influenced seed dormancy-breaking and germination requirements in highly species-rich families such as the Asteraceae (ca. 30,000 species, sunflower family), Myrtaceae (ca. 6,000, Eucalyptus family) and Rubiaceae (ca. 13, 460 species, coffee family).

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Date:
Location:
THM 116

"Botanical research at Eastern Kentucky University: Fantastic ferns, conservation and beyond"

SelfieDr. Sally Chambers

Abstract:

Kentucky is a botanically diverse state home to over 2,000 native plants and more than 400 taxa that are of conservation concern. Kentucky’s native plants are phylogenetically diverse, and a subset of taxa reflect Kentucky’s geologic history as tropical relicts. This is especially true for the ferns in Kentucky, as many species occupy sandstone rock shelters which buffer extreme climatic conditions much like cave ecosystems. These microclimatic pockets create unique distribution patterns for the ferns that occupy this niche space, and even further partition the fern life cycle such that some crevices host only gametophytes while others host both gametophyte and sporophyte generations. This talk will focus on decades of work conducted in these unique rock shelter environments and the spatial differentiation of fern generations (gametophyte/sporophyte) in Kentucky, the Appalachians and beyond. Ecological research focusing on topics such as local adaptation, physiological tolerance limits, and population differentiation will be discussed. The remainder of the talk will highlight the botanical resources housed at Eastern Kentucky University and the utility of these natural history collections to scientists worldwide.



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Date:
Location:
THM 116

"The Evolution of Cell Types in the Cerebral Cortex"

SelfieDr. Maria Antonietta Tosches | Tosches Lab

Abstract:

The cerebral cortex is arguably the brain area that underwent the most profound transformations in vertebrate brain evolution. The expansion of the cerebral cortex in mammals was accompanied by an explosion of neuronal diversity. To discover general principles underlying the evolution of neuron types and circuits, we study the simple cerebral cortices of non-mammalian vertebrates. Our recent work has focused on the Spanish newt Pleurodeles waltl, a species with a key phylogenetic position in the vertebrate tree. We are investigating the neuroanatomy, cell type composition, and function of the Pleurodeles brain using a combination of modern neuroscience tools.

Our work on amphibians and reptiles indicates that the cerebral cortex of ancestral tetrapods was layered, with two main classes of neurons with distinct laminar positions, molecular identities, and long-range projections. In salamanders, these two layers are generated sequentially from multipotent progenitors in an outside-in sequence. We propose that in mammals new types of pyramidal neurons evolved from these two ancestral classes by diversification, through the emergence of novel gene regulatory interactions during neuronal differentiation.

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Date:
Location:
THM 116

CANCELLED | "Dissecting Ciliopathies: From Molecular Mechanism to Potential Treatments"

SelfieDr. Samantha Brugmann | Brugmann Lab

Bio:

Dr. Samantha Brugmann is a developmental biologist studying craniofacial development and disease. Her longterm goal is to help children with craniofacial anomalies by generating tissue amenable for surgical repair. To achieve this goal, her lab specifically focuses on the role the primary cilium during craniofacial development and the craniofacial anomalies that arise when the cilium do not function properly. Projects in her lab utilize avian, murine and humaninduced pluripotent stem cells to gain a better understanding of the molecular mechanisms associated with craniofacial anomalies. In addition to using existing animal models to understand human craniofacial disorders, her lab also sequences patients and generates cell-based models to uncover novel genetic causes for craniofacial ciliopathies.



Abstract:

The Brugmann Lab focuses on the understanding molecular and cellular processes important for craniofacial development and the onset of craniofacial anomalies (CFAs). CFAs represent approximately one third of all birth-defects. For the past decade, my research program has centered on treating these conditions by garnering a fundamental understanding of craniofacial development and pathological mechanisms associated with CFAs. We have specifically focused on a class of CFAs called ciliopathies, which are caused by disruptions to a cellular organelle called the primary cilium. Ciliopathies represent a fast-growing group of disorders, that can affect up to 1 in 800 people. My lab was the first to report that the craniofacial complex is the primary organ system affected in 30% of all ciliopathies, and thus coined the term craniofacial ciliopathies. My lab uses murine, avian and human model systems to understand molecular mechanisms associated with ciliopathies. Furthermore, we use these model systems to identify potential therapeutic avenues to treat this class of diseases. 

Date:
Location:
THM 116

"Planarian Stem Cells: A Model for Limitless Regeneration and Renewal"

SelfieDr. Carrie Adler | Adler Lab

Bio:

Carrie is currently an Assistant Professor in the Department of Molecular Medicine at Cornell University, where she started her lab in 2015. She attended college at Wesleyan University and afterwards worked as a technician with Bruce Mayer at Harvard Medical School, studying signal transduction pathways. For graduate school, Carrie enrolled in the Tetrad program at UCSF, joining Cori Bargmann's lab to study neural development in C. elegans. As a postdoc, Carrie trained with Alejandro Sánchez Alvarado at the University of Utah and the Stowers Institute for Medical Research.

Abstract:

Throughout our lives, we are constantly exposed to insults, including injuries, disease, and environmental toxins. Frequently referred to as a ‘fountain of youth’ given their potential for rejuvenation, stem cells have the capacity to restore damaged tissue. In most model organisms, regenerative capacity is limited and stem cells are scarce, which has made it difficult to pinpoint the mechanisms regulating their behavior. In addition, stem cell exhaustion occurs as we age, diminishing our ability to repair damaged tissues. Finally, while we have made significant progress in recapitulating organ growth in vitro, how might these tissues be used in humans to restore physiological function?

My research program has probed these questions in an emerging model organism, planarian flatworms. These animals have long been regarded as champion regenerators because they can rapidly replace any tissue that’s been damaged or lost, including the nervous system. The basis of this unlimited renewal lies in an abundant population of stem cells. My lab’s primary goals are to understand how these cells sense and respond to injury, and how they maintain genome integrity through repeated cell divisions that occur during regeneration.

Check out the seminar here!

Date:
Location:
THM 116

Thomas Hunt Morgan Annual Lecture 2023: "African Integrative Genomics: Implications for Health and Disease"

Selfie Dr. Sarah Tishkoff | Tishkoff Lab

 

Sarah Tishkoff is the David and Lyn Silfen University Professor in Genetics and Biology at the University of Pennsylvania, holding appointments in the School of Medicine and the School of Arts and Sciences. She is also Director of the Penn Center for Global Genomics and Health Equity.

Dr. Tishkoff studies genomic and phenotypic variation in ethnically diverse Africans. Her research combines field work, laboratory research, and computational methods to examine African population history and how genetic variation can affect a wide range of traits – for example, why humans have different susceptibility to disease, how they metabolize drugs, and how they adapt through evolution.

Dr. Tishkoff is a member of the National Academy of Sciences and a recipient of an NIH Pioneer Award, a David and Lucile Packard Career Award, a Burroughs/Wellcome Fund Career Award, an ASHG Curt Stern award, and a Penn Integrates Knowledge (PIK) endowed chair. She is a member of the Scientific Advisory Panel for the Packard Fellowships for Science and Engineering and the Board of Global Health at the National Academy of Sciences and is on the editorial boards at PLOS GeneticsGenome Research; G3 (Genes, Genomes, and Genetics);Cell.

Her research is supported by grants from the National Institutes of Health, the National Science Foundation, the Chan Zuckerberg Institute, and the American Diabetes Association.

Abstract:

Africa is the ancestral homeland of all modern human populations within the past 300,000 years.  It is also a region of tremendous cultural, linguistic, climatic, phenotypic and genetic diversity.   Despite the important role that African populations have played in human history, they remain one of the most underrepresented groups in human genomics studies. A comprehensive knowledge of patterns of variation in African genomes is critical for a deeper understanding of human evolutionary history and the identification of functionally important genetic variation that plays a role in both normal variation and disease risk.  Here I will describe our studies of genomic variation in ethnically and geographically diverse Africans in order to reconstruct human evolutionary history and identify candidate genes that play a role in adaptation to infectious disease, diet, high altitude, stature, and skin color. I will highlight recent research integrating data from a genome wide association study of skin pigmentation in Africans and scans of natural selection from whole genome sequencing. Combining high-throughput reporter assays, Hi-C, CRISPR-based editing, and melanin content assays, we identified novel regulatory variants that impact melanin levels in vitro and modulate human skin color variation. Additionally, we identified a novel gene regulating pigmentation by impacting genes involved in oxidative phosphorylation and melanogenesis. These results provide insights into the mechanisms underlying human skin color diversity and adaptive evolution.

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Date:
Location:
THM 116
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