CSB Deptl Seminar: Prof. Tim Hughes, Dept of Medical Genetics & Microbiology, University of Toronto
CSB Departmental Seminar
Prof. Tim Hughes
Dept of Medical Genetics & Microbiology
University of Toronto
"Kaleidoscopic Evolution of C2H2 Zinc Finger Proteins"
Host: Prof. Maurice Ringuette
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
The C2H2 zinc finger (C2H2-ZF) is found in across the eukaryotes, and is the most numerous protein domain in many metazoans, representing nearly half of all human transcription factors. It is also one of the few protein domains that display widespread diversification, such that a majority of the ~700 human C2H2 proteins are expected to have unique binding motifs. Most C2H2 proteins, however, are largely unstudied in terms of both function and biochemistry, and it is unclear whether they even bind DNA and regulate transcription.
I will describe efforts in my lab to systematically characterize C2H2 proteins in human and across eukaryotes. We find that most C2H2 domains and most C2H2 proteins do bind DNA in a sequence specific manner. Rapid diversification of binding motifs in metazoans is facilitated by contribution of non-DNA-contacting residues to binding affinity, relative to non-metazoan C2H2 domains, enabling virtually unlimited combinations of DNA contacting residues, and continuous “kaleidoscopic” evolution over relatively short evolutionary timescales. We introduce new methods to integrate the identity of DNA contact residue identities with other residues and ChIP-seq data to improve both “recognition code” models and derivation of motifs from ChIP-seq. We observe widespread binding of C2H2 proteins to endogenous retroelements, providing a mechanism driving expansion and diversification. Surprisingly, we also find that the spectrum of C2H2 protein-protein interactions in living cells is nearly as diverse as the C2H2 DNA binding sites, suggesting that diversification involves multiple molecular mechanisms.
CSB Deptl Seminar: Prof. Sally Horne-Badovinac, Molecular Genetics and Cell Biology, The University of Chicago
CSB Departmental Seminar
Prof. Sally Horne-Badovinac
Molecular Genetics & Cell Biology
The University of Chicago
"Going in Circles gets you Somewhere – Mechanisms Controlling Egg Chamber Elongation in Drosophila"
Host: Prof. Maurice Ringuette
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
During development, discrete organs and entire body plans emerge from the coordinate actions of individual cells. These complex morphogenetic events require dynamic regulation of cell shape, polarity, and adhesion across cell populations, as well as reciprocal interactions between cells and their extracellular matrix (ECMs). My lab seeks to understand how these diverse cellular behaviors are orchestrated to produce an organ's shape. To this end, we are using genetic and cell biological approaches in Drosophila to investigate how a simple organ-like structure called an egg chamber is transformed from a spherical to an ellipsoidal shape. Egg chamber elongation depends on a dramatic collective cell migration event, in which the egg chamber’s outer epithelial cells crawl along their adjacent basement membrane ECM. This process causes the entire egg chamber to rotate within the matrix. This seminar will discuss two key aspects of this motility. First, I will show how tissue movement synergizes with new protein secretion to construct a polarized network of fibrils within the basement membrane that are required for elongation morphogenesis. Second, I will introduce a new planar signaling system that controls the collective migration itself.
CSB Deptl Seminar: Prof. Bret Pearson, Dept of Molecular Genetics, University of Toronto
CSB Departmental Seminar
Prof. Bret Pearson
Dept of Molecular Genetics
University of Toronto
"The Queen is Dead: Understanding Stem Cell Hierarchies using Freshwater Planarians"
Host: Prof. Dorothea Godt
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
The freshwater planarian (flatworm) has been used by biologists for over 100 years to study regeneration, however, over the past decade it is re-emerging as a powerful model for stem cell biology. Here we explore the molecular mechanisms by which planarians control their pluripotent adult stem cells in order to replace specific numbers and types of differentiated daughter cells. We apply both whole-organism and single cell RNA-sequencing and find that an RNA-binding protein, MEX3, is involved in the critical decision on whether a cell remains a stem cell, or differentiates. From this, we have pieced together the cellular hierarchy from stem cell to epithelial cell, and find that it is relatively shallow, with no master stem cell type ("Queen") at the top.
CSB Deptl Seminar: Prof. Alexei Savchenko, Chemical Engineering & Applied Chemistry, University of Toronto
CSB Departmental Seminar
Prof. Alexei Savchenko
Dept of Chemical Engineering and Applied Chemistry
University of Toronto
"Visualizing the Host-hijacking Toolkit of Pathogenic Bacteria"
Host: Prof. Peter McCourt
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
My research focuses on the molecular aspects of bacterial pathogenesis. Primarily we are interested in understanding the function of bacterial proteins involved in the sophisticated “biochemical cross-talk” between pathogen and host and which are critical for the survival and proliferation of the pathogen. This class, often collectively called ‘effectors’, includes bacterial proteins delivered into the host cell via specialized secretion systems. While these bacterial proteins have different mechanisms of delivery into the host cytoplasm, they all share the ability to alter host cellular pathways/systems to promote pathogenesis and contribute to virulence. Distantly related bacterial pathogens may harbor closely related effectors, suggesting that these effectors are targeting highly conserved host pathways and that one pathogenic mechanism can give rise to a multitude of diseases that range from bubonic plague in humans to fire blight in fruit trees. Thus, characterization of the specific functions of bacterial effectors will not only advance our general understanding of pathogenesis process but can also lead to discovery of novel eukaryotic signaling pathways.
In my presentation I will describe our advances in understanding of molecular function of bacterial effectors hijacking host ubiquitin proteasome system (UPS), which has emerged as one of the main targets for effector proteins. While bacteria generally lack the UPS, the bacterial pathogens encode many effectors with UPS- specific functions with particularly large and diverse group mimicking the function of eukaryotic ubiquitin protein ligases also known as E3 enzymes.
CSB Deptl Seminar: Prof. Gerald Berkowitz, Dept of Plant Science & Landscape Agriculture, University of Connecticut
CSB Departmental Seminar
Prof. Gerald Berkowitz
Dept of Plant Science & Landscape Agriculture
University of Connecticut
"Ca2+ Signaling in Plants: Molecular Mechanisms Underlying Cell Immune Response to Pathogens, Hormone Control of Plant Growth, and Stem Cell Signaling"
Host: Prof. Keiko Yoshioka
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
Transient elevation of intracellular Ca2+ is the most common signal transduction mechanism present in any living organism. In plants, this cytosolic secondary messenger is involved in dozens of signaling pathways that orchestrate cellular response to environmental, developmental, and physiological cues. However, only recently have specific Ca2+ conducting proteins been associated with specific signal transduction pathways. Further, the molecular mechanisms that link cell membrane receptor perception of extracellular signals to Ca2+ elevations in the plant cell cytosol remain, essentially, unknown and/or the current models speculative and controversial. The molecular nature of plant Ca2+ channels and Ca2+ sensors that transmit the signal to downstream response systems are quite distinct from those present in animals. Work will be presented about this biological paradigm. Cyclic nucleotide gated Ca2+-conducting ion channels (CNGCs) were characterized using electrophysiological and biochemical analyses. Genetic tools were used to associate these channels with a number of signaling pathways. Studies were also undertaken to associate CNGCs with cell membrane receptors that are involved in their activation, thus linking receptor function with the signal transduction pathways controlled by these channels. Finally, some Ca2+ sensors (calmodulin and Ca2+-dependent protein kinases) and other molecular steps were identified as transmitters of these signals to control cell responses.
CSB Deptl Seminar: Prof. Tod R. Thiele, Dept of Biological Sciences, University of Toronto at Scarborough
CSB Departmental Seminar
Prof. Tod R. Thiele
Department of Biological Sciences
University of Toronto at Scarborough
"Neural Circuits that Mediate Visually Driven Behaviours in Larval Zebrafish"
Host: Prof. Vince Tropepe
Refreshments will be served. All are welcome!
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
A fundamental activity of the brain is to transform sensory information into goal-directed movements. We still possess only a rudimentary understanding of how the brain performs sensorimotor transformations despite their necessity to virtually all of our daily activities. Technological advances in systems neuroscience and zebrafish research over the past decade present an unprecedented opportunity to define how brain circuitry gives rise to vertebrate behaviour. In my talk, I will describe research which identified circuits in the larval fish that underlie visually mediated behaviours. These include circuits in retinorecipient regions dedicated to prey capture as well as premotor circuitry that controls postural steering during swims. Analysis of both of these circuits supports the existence of highly modular neural architectures in zebrafish. I will also discuss future plans for my laboratory at the University of Toronto Scarborough where we will investigate circuits that govern the selection of behavioural motor programs. Lastly, I will describe a strategy that combines optogenetics with high throughput drug screening to identify compounds that modulate specific motor microcircuits in the brain.
CSB Graduate Student and Post-doc Seminar
Pizza lunch
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Speaker1: Gianni Castiglione (Chang Lab)
Title: Molecular Mechanisms of Cold-Adaptation in Vertebrate GPCR Dim-Light Sensor Rhodopsin
Speaker2: Stephanie Prezioso (Christendat Lab)
Title: Regulation of Quinate Metabolism in Listeria monocytogenes
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CSB Deptl Seminar: Prof. Mary Wildermuth, Plant & Microbial Biology, University of California, Berkeley
CSB Departmental Seminar
Prof. Mary Wildermuth
Plant & Microbial Biology
University of California, Berkeley
"Plant Host Manipulation by Powdery Mildews:
Insights into Obligate Biotrophy & Host Processes"
Friday, December 11, 2015 at 2 p.m.
Ramsay Wright Building, Room 432
Host: Prof. Keiko Yoshioka <keiko.yoshioka@utoronto.ca>
Abstract:
Plant-pathogen interactions are marvellously intricate, diverse, and highly integrated, with the disease outcome of the interaction dependent upon both pathogen and plant host factors and processes. My long-term goal is to understand the mechanisms by which hosts and pathogens interact to redirect host metabolism and physiology. By studying compatible interactions, where disease occurs, we can identify host factors that alter the extent of pathogen growth and reproduction resulting in enhanced susceptibility or resistance. These host factors may be involved in host defense or utilized by the pathogen for its growth and reproduction. Arabidopsis thaliana is our model host of choice because of its small, sequenced diploid genome, six-week generation time, and unparalleled associated genetic and genomic resources. In addition, Arabidopsis research on phytohormones and disease resistance has both translated to agronomically important species and led to the identification of host regulatory components impacting human health (e.g. NB-LRR proteins involved in innate immunity). Furthermore, because pathogens have evolved to effectively manipulate fundamental host processes and this manipulation often occurs as an induced, localized response, plant pathosystems can uniquely allow us to elucidate components of fundamental biological processes such as the cell cycle.
In my laboratory, we generate, analyze, and integrate biological information across disciplines to: (1) Discover host processes of importance to an interaction through the use of systems-level data, (2) Uncover the process components and their regulation through detailed biochemical, molecular genetic, cell biological, and genomic analyses, (3) Elucidate the functional role of a process in the context of a given plant pathosystem using theoretical, informatic, and experimental approaches.
CSB Deptl Seminar: Prof. Patrick Laprise, Molecular Biology, Medical Biochemistry and Pathology/Oncology, Université Laval
CSB Departmental Seminar
Prof. Patrick Laprise
Molecular Biology, Medical Biochemistry
and Pathology/Oncology
Université Laval
"Molecular Mechanisms Orchestrating Epithelial Cell Polarity"
Friday, December 4, 2015 at 2 p.m.
Ramsay Wright Building, Room 432
Host: Prof. Dorothea Godt <d.godt@utoronto.ca>
Abstract:
The functions of epithelial cells rely on the asymmetric distribution of many cellular constituents—a structural organization referred to as epithelial polarity. The polarized architecture of epithelial cells also shapes tissues during development. The protein machinery establishing epithelial polarity is conserved from flies to humans, reflecting its significance for the physiology of metazoans. For instance, the protein Yurt (Yrt) is a critical regulator of epithelial cell polarity in both flies and mammals. Our general objective is to further define Yrt function and regulation to illuminate the protein network that establishes epithelial polarity, thereby providing a better understanding of the molecular mechanisms sustaining epithelial tissue morphogenesis and physiology. My presentation will cover our recent work highlighting post-translational regulation of Yrt activity, and defining the oligomeric interfaces of this protein.
CSB Deptl Seminar: Prof. Trevor Moraes, Dept of Biochemistry, University of Toronto
CSB Departmental Seminar
Prof. Trevor Moraes
Department of Biochemistry
University of Toronto
"Bacterial Mechanisms to Overcome Nutritional Immunity"
Friday, November 27, 2015 at 2 p.m.
Ramsay Wright Building, Room 432
Host: Prof. Dinesh Christendat <dinesh.christendat@utoronto.ca>
Abstract:
The battle for nutrients between invading bacteria and its host is extremely complex. Mammals have evolved to possess ‘Nutritional immunity’ - a mechanism to sequester nutrients like zinc and iron thus limiting their availability to invading pathogens. In response, the evolving bacterial pathogen keeps pace with mammalian defences using specialized nutrient uptake system to alleviate the nutritional immunity pressure. Herein I will discuss our structural and functional insights into several bacterial nutrient acquisition systems (including the Bacterial Transferrin Receptor -TbpA/TbpB and a Zn uptake receptor -ZnuD) and a new sugar-phosphate transporter that provide bacteria with mechanism to acquire nutrients while within their host environment.