CSB Seminar: Professor Ian Scott, Senior Scientist, Developmental & Stem Cell Biology, SickKids, Associate Professor, Department of Molecular Genetics, University of Toronto

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Departmental Seminar

Professor Ian Scott
Senior Scientist, Developmental & Stem Cell Biology, SickKids
Department of Molecular Genetics, University of Toronto
“Cardiac lineage development in zebrafish”

 

Host:  Prof. Ashley Bruce <ashley.bruce@utoronto.ca>

Abstract:

We are interested in studying how the cardiac lineage is first specified and then elaborated during the earliest events of vertebrate development. Towards this end, we have been examining the zebrafish grinch mutant, which lacks all cardiac progenitors. This analysis has shown us that the GPCR encoded by the aplnrb gene fine-tunes Nodal signalling during gastrulation, resulting in a loss of myocardial progenitor specification and/or migration. To further analyze the cardiac progenitor lineage, we have applied single cell RNA-seq and ATAC-seq approaches to define novel genes and regulatory elements specific to this lineage. In preliminary work, this has revealed novel genes and conserved regulatory elements for future analysis. Following cardiac lineage specification, we have found that Hey2, a transcription factor, plays a key role in holding proliferation and cardiac contribution of second heart progenitors in check. Intriguingly, retinoic acid (RA) signalling restricts hey2 expression both during cardiac development and adult cardiac regeneration, suggesting that cardiac progenitor development may be re-deployed during adult cardiac repair.

Video Conferencing at UTM (DV3138) & UTSc (MW229)


CSB Seminar: Prof. Adam C. Martin, Massachusetts Institute of Technology, Department of Biology

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Departmental Seminar

Prof. Adam C. Martin
Massachusetts Institute of Technology
Department of Biology

"Organizing the contraction that changes tissue shape"

Host:  Prof. Ulrich Tepass <u.tepass@utoronto.ca>

Abstract:

Cells generate forces in tissues to sculpt the myriad of tissue shapes that occur in an organism.  An engine that is associated with cell and tissue shape changes in diverse contexts is a dynamic actomyosin meshwork or cortex underlying the plasma membrane.  In epithelial cells, contraction of the apical actomyosin cortex can drive apical constriction. I will describe how the apical cortex of non-muscle cells can adopt a polarized structure that topologically resembles a muscle sarcomere.  We discovered that establishing this sarcomere-like organization in the apical cortex requires a dynamic upstream signaling network that surprisingly involves, not only activation, but inhibition of the RhoA GTPase.

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Video Conferencing at UTM (DV3138) & UTSc (MW229)


CSB Seminar: Prof. Ross Sozzani, Department of Plant and Microbial Biology, North Carolina State University.

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Departmental Seminar

Prof. Ross Sozzani
Department of Plant and Microbial Biology
North Carolina State University

"Inferring gene regulation networks that control maintenance and identity of the Aradidopsis root stem cells"

Host:  Prof. Nicholas Provart  <nicholas.provart@utoronto.ca>

 

Abstract:

The stem cells in the tip of the Arabidopsis root form all the root tissues by undergoing rounds of coordinated cell division while maintaining their undifferentiated state. While a number of transcription factors involved in root stem cell maintenance have been described, a comprehensive view of the transcriptional signature of the stem cells is lacking. A better understanding of the transcription factors that maintain the stem cells and control each stem cell’s identity would give us more insight into how the growth and development of the root is initiated. In this work, we generated a model of the transcriptional mechanisms underlying the identity and maintenance of the Arabidopsis root stem cells that links known and newly predicted factors involved in these processes. For this, we first sorted and transcriptionally profiled four stem cell populations. We then developed GENIST, an algorithm for GEne regulatory Network Inference from Spatio Temporal Data. These datasets are processed by two computational strategies of clustering and Dynamic Bayesian Networks, which are integrated into our algorithm to increase the overall prediction capacity of our method. We inferred GRNs in the Arabidopsis root stem cell niche by applying GENIST to a combination of our stem cell dataset and a public time-series dataset. Our approach led to a map of genetic interactions that orchestrate the transcriptional regulation of stem cells. In addition to linking known stem cell factors, our resulting GRNs predicted novel implications of TFs in stem cell molecular events. We experimentally validated some of our key predicted transcription factors, which confirmed the robustness of our algorithm and our resulting networks.

 

Video Conferencing at UTM (DV3138) & UTSc (MW229)

CSB Seminar: Prof. Jamie Fitzgerald, Henry Ford Hospital

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Departmental Seminar

Prof. Jamie Fitzgerald
Henry Ford Hospital
"Microgravity and articular cartilage:  Is Spaceflight bad for your joints?"

 

Host:  Prof. Les Buck <les.buck@utoronto.ca>

 

Abstract:

The altered biomechanical environment of microgravity leads to a transient disease state in musculoskeletal tissues characterized by the progressive demineralization of bones and loss of skeletal muscle bulk. However, these tissue changes are reversed upon return to a 1G environment and normal tissue function is restored. The response to microgravity of articular cartilage, a biomechanically important tissue located at the ends of bones in synovial joints, has not been investigated. The effects of extended periods of unloading on articular cartilage are important to define because, unlike bone and skeletal muscle, articular cartilage has a very poor capacity to repair and significant microgravity-induced articular cartilage degradation may have long-term health consequences for flight personnel. To address whether cartilage is negatively impacted by microgravity we investigated the cellular and molecular responses of mouse articular cartilage exposed to 30 days of microgravity as part of the Biospecimen Sharing Program flown on the BION-M1 capsule. Proteoglycan levels and changes in gene expression due to microgravity in articular cartilage were compared with those in sternal fibrocartilage which was used as a non-weight-bearing control. The talk will discuss these data and the potential impact of microgravity-induced cartilage changes on long-term Spaceflight.

Video Conferencing at UTM (DV3138) & UTSc (MW229)

CSB Seminar: Prof. J. Todd Blankenship, Director, Molecular and Cellular Biophysics Program, Department of Biological Sciences, University of Denver

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Departmental Seminar

Prof. J. Todd Blankenship
Director, Molecular and Cellular Biophysics Programs
Department of Biological Sciences
University of Denver

"Membrane-dependent cell ratcheting and tissue morphogenesis"

Host:  Prof. Tony Harris <tony.harris@utoronto.ca>

Abstract:
The control of cell shape is a fundamental property required for epithelial tissue architecture and function. Tensile actomyosin forces have been conventionally thought to drive changes in epithelial cell shape and tissue remodeling. However, here we have examined the coordination of membrane trafficking and cytoskeletal networks to direct progressive changes in cell shape. We show that the AP Patterning system engages a membranous ratchet at the plasma membrane to effect interface contraction during cell intercalation. Our results suggest that endocytic and cytoskeletal forces converge on compartmental behaviors to direct cell shaping events.

Video Conferencing at UTM (DV3138) & UTSc (MW229)


CSB Seminar: Dr. Cyrus Martin, Senior Scientific Editor, Current Biology

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Departmental Seminar

Dr. Cyrus Martin
Senior Scientific Editor
Current Biology
"Science Publishing: An Editor's Perspective"

 

Host:  Prof. John Peever <john.peever@utoronto.ca>

Abstract: 

Interested in what happens behind the scenes at a scientific journal? Come hear Cyrus Martin, Senior Scientific Editor of Current Biology, discuss the life of a professional science editor. You’ll learn about both the nuts and bolts of how a manuscript winds its way from submission to (hopefully) publication and also the goals of a general biology journal, which include the aim of fostering communication between scientists working in different fields. Finally, emerging changes to science publishing, such as the way scientists access literature and the growing popularity of preprints will be discussed.

Video Conferencing at UTM (DV3138) & UTSc (MW229)


CSB Special Seminar: Professor Jeff Chang, Department of Botany and Plant Pathology, Oregon State University

CSB Special Seminar

Professor Jeff Chang
Department of Botany and Plant Pathology
Oregon State University
"Evolution of Agrobacterium and its Virulence Plasmids"
Thursday, December 15, 2016
2:00-3:00 p.m. at RW 432
Host: Darrell Desveaux (darrell.desveaux@utoronto.ca)
Abstract:

We sequenced and analyzed genome sequences from over 175 Agrobacterium strains isolated from diseased plants and their environments. Based on chromosome sequences, the strains can be circumscribed within eight different clades, with some representing new taxa of Agrobacterium. Comparisons between the eight clades and sister clades yielded results that further exacerbate the fuzziness in taxonomical and biological distinction from mutualistic rhizobia. We also operationally categorized Ti/Ri plasmids into groups and revealed preferences between plasmids, bacterial host, and plant host. The generalizations that were drawn additionally help provide valuable insights into the dynamic evolutionary processes that shaped Ti/Ri plasmids and Agrobacterium virulence.

 


CSB Special Seminar: Professor Edgar Spalding, Department of Botany, University of Wisconsin-Madison

CSB Special Seminar

Professor Edgar Spalding
Department of Botany
University of Wisconsin-Madison
"100 years of transporting auxin: from “correlative relationships” to molecular channels"
Thursday, December 1, 2016
3:30-4:30 p.m. at RW 432
Host: Keiko Yoshioka (keiko.yoshioka@utoronto.ca)
Abstract:

Movement of the auxin (indole-3-acetic acid) through plant tissues and organs is as much a part of this hormone's influence as the molecular actions by which it regulates much growth and development. Movement and action of the hormone were wrapped up into a vague notion called "correlation" by plant physiologists until the chemical identity of auxin was elucidated and phenomena such as tropisms were demystified almost 100 years ago. This presentation will survey the origins of the concept of a hormone with a highly controlled macroscopic transport mechanism before considering how well current information about PIN and ABCB membrane proteins supply a satisfactory explanation for the phenomenon usually referred to as polar auxin transport. Currently, most people believe that polar auxin transport results from auxin-conducting channels in the PIN family being localized predominantly at the 'downstream' ends of each cell in a path. The data from publications that established the current paradigm will be summarized along with new molecular, genetic, and electrophysiological data that indicate the mechanism may be more complicated. 

Selected Recent Publications

Wu G, Carville JS*, Spalding EP (2016) ABCB19-mediated polar auxin transport modulates Arabidopsis hypocotyl elongation and the endoreplication variant of the cell cycle. The Plant Journal 85: 209-218

Cho M, Henry EM, Lewis DR, Wu G, Muday GK, Spalding EP (2014) Block of ATP-binding cassette B19 ion channel activity by 5-nitro-2-(3-phenylpropylamino)-benzoic acid impairs polar auxin transport and root gravitropism Plant Physiology 166: 2091-2099

Moore CR, Johnson LS, Kwak I-Y, Livny M, Broman KW, Spalding EP (2013) High-throughput computer vision introduces the time axis to a quantitative trait map of a plant growth response. Genetics 195: 1077-1086

Vincill ED, Clarin AE, Molenda JN, Spalding EP (2013) Interacting glutamate receptor-like proteins in phloem regulate lateral root initiation. The Plant Cell 25: 1304-1313


CSB Seminar: Prof. Timothy Devarenne, Biochemistry and Biophysics, Agriculture and Life Sciences, Texas A&M University, College Station, Texas

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Departmental Seminar

Prof. Timothy Devarenne
Dept of Biochemistry & Biophysics
Agriculture & Life Sciences
Texas A&M University, College Station

"Cell Death Control and Hormonal Signaling during the Defense Response of Tomato to Bacterial Pathogen Pseudomonas syringae"

Host:  Prof. Keiko Yoshioka <keiko.yoshioka@utoronto.ca>

Abstract:
The Devarenne lab is interested in studying the molecular mechanisms used by plants to defend against the bacterial pathogen Pseudomonas syringae. Specifically, we study how tomato plants control cell death as a defense mechanism against P. syringae. During plant resistance to pathogens induction of host cell death is used to kill pathogen cells and reduce pathogen spread throughout the host. We have shown the tomato protein kinase Adi3 to be a suppressor of cell death in the absence of pathogen, and functions to control induction the cell death needed during resistance to P. syringae. Results will be presented summarizing these studies. Additionally, the Devarenne lab is studying how the perception of P. syringae controls hormone signaling needed for induction of tomato defense mechanisms. It is known that the hormone salicylic acid (SA) is needed for induced defense gene expression in response to P. syringae, and this response can be inhibited by the hormone jasmonic acid (JA) leading to reduced resistance to P. syringaeThus, JA signaling is inhibited during defense against P. syringae in order to maximize SA-mediated defenses. We are studying a new angle on the inhibition JA signaling by analyzing the inhibition of JA biosynthesis in response to P. syringae. Results will be presented on the role of threonine deaminase 2 (TD2) in the biosynthesis of active versions of JA and the regulation of TD2 in response to P. syringae.

Video Conferencing at UTM (DV3138) & UTSc (MW229)


CSB Seminar: Prof. Mikko Taipale, Dept of Medical Genetics, Donnelly Centre for Biomedical Research, University of Toronto

Cell & Systems Biology
Departmental Seminar

Prof. Mikko Taipale
Dept of Medical Genetics
Donnelly Centre for Biomedical Research
University of Toronto

"Systematic Characterization of Human Chaperone/Client Interaction Networks"

Host:  Prof. Maurice Ringuette <maurice.ringuette@utoronto.ca>

Abstract:
Chaperones are abundant, highly conserved cellular proteins that promote the folding and function of their substrate proteins (clients). In vivo, chaperones also associate with a large and diverse set of cofactors (cochaperones) that regulate their specificity and function. However, how these co=chaperones regulate protein folding and whether they have chaperone-independent biological functions is largely unknown. My lab is characterizing human chaperone/co-chaperone/client interaction networks with multiple functional proteomics approaches. Currently, our main focus is on the Hsp70/Hsp40 chaperone/co-chaperone network, which regulates thousands of diverse client proteins in all organisms.

Video Conferencing at UTM (DV3138) & UTSc (MW229)