Dr. Zoe Panchen The blossoming of the Arctic: Natural history records as a resource to study plant responses to climate change The Arctic is experiencing some of the most dramatic changes in climate with temperatures rising at treble the rate of the global average. Phenology, the timing of natures seasonal events, is often related to temperature and, as the climate warms, Arctic flowering and fruiting times are generally shifting earlier. Natural History records of pressed plants (herbarium specimens) are often collected in flower or fruit and offer a snap shot of flowering and fruiting times over the past century or more. Herbarium specimens are thus an excellent resource for predicting how plants will respond to climate change. In this talk, I will discuss how Arctic plants are responding to climate change, focusing on findings from my Nunavut plant phenology research using herbarium specimens and long-term phenology monitoring. I will conclude my presentation by describing my current research on evolutionary and life history trait patterns in Arctic plant phenological responses to climate change.
Dr. Liana Burghardt Assistant Professor, Plant Sciences Department Pennsylvania State University Evolving together, evolving apart: Measuring the fitness of rhizobial bacteria in and out of symbiosis with leguminous plants The nitrogen-fixing symbiosis between legumes and rhizobia represents fertile ground to study the evolution and ecology of beneficial plant-microbe interactions. In facultative relationships where both partners can live independently, soil selection patterns can influence the process of host adaptation and vice versa. This talk will describe a twist on an ‘evolve and resequence’ methodology we developed to measure the relative success of scores of co-existing rhizobia isolates in host and nonhost environments. Our team of researchers has measured Sinorhizobium strain fitness in nodules of Medicago legume hosts and as free-living saprophytes in the soil. By synthesizing results from multiple experiments, we examine patterns of rhizobial fitness correlations within and between host and non-host environments. We found 1) only between host species do we observe negative fitness correlations (evolutionary constraint), 2) that in soil mesocosms, temperature and salinity influence isolate-level selection more strongly than other soil characteristics, and 3) that adaptation to nonhost soil environments is unlikely to constrain or undermine rhizobial adaptation to host environments. Our results suggest it may be possible to leverage host genetic variation to manipulate rhizobial communities and optimize rhizobial fitness without undermining the soil survival of rhizobia and that co-occurring Medicago species may function to maintain rhizobial diversity in soils.
DR. LEIGH MCGAUGHEY The Great River Rapport: A collaborative approach to assessing and communicating the ecological health of the Upper St. Lawrence River Born out of the question “What is the health of the St. Lawrence River?” the River Institute, in partnership with the Mohawk Council of Akwesasne, initiated an ecosystem health report on the river. Framed in the Ohén:ton Karihwatéhkwen (Words that come before all else), the project is a science-based, ecosystem health report informed by community-driven research questions. The Great River Rapport engages Indigenous partners, community members and groups, academics, students, and government agencies to produce scientific findings, and translate science into compelling stories and formats that motivate action. It also performs the role of identifying data gaps for future research. Through a participatory approach, a suite of 35 ecological indicators have been selected to reflect the health of the river system. Progress on the project to date will be shared, along with key findings from a selection of the fish indicators (see www.riverrapport.ca). Assistant Professor and Canada Research Chair in Plant Cell Biology Department of Cell and Systems Biology, University of Toronto Building the plant cell wall from the inside out The plant cell wall is a polysaccharide-based extracellular matrix that surrounds and protects all plant cells. Since plants are constantly growing and developing within the confines of their cell walls, plant cells must be in constant communication with their cell walls. Furthermore, cell walls are a critical line of defense between plant cells and their environment; changes to the cell wall are often early warning signs of pathogen attack or abiotic stress, and plants fortify their cell walls in response to these stresses. This ongoing communication between the plant cells and their cell walls is collectively called “cell wall signaling”. The McFarlane Lab at The University of Toronto studies the molecular mechanisms of cell wall signaling and responses, including cell wall secretion and remodeling. We have recently characterized two different pathways that affect cell wall matrix polysaccharide synthesis at the Golgi apparatus. Interestingly, these cell wall synthesis defects result in changes to Golgi structure and function including inappropriate cell wall synthesis, secretion, and/or remodelling. These cellular phenotypes ultimately result in defects in coordinated cell growth and loss of tissue integrity, resulting in dramatic consequences for plant growth and development
University of Rochester The evolutionary history of Drosophila simulans Y chromosomes reveals molecular signatures of resistance to sex ratio meiotic drive The recent evolutionary history of the Y chromosome in Drosophila simulans, a worldwide species of Afrotropical origin, is closely linked to that of X-linked meiotic drivers (Paris system). The spread of the Paris drivers in natural populations has elicited the selection of drive resistant Y chromosomes. To infer the evolutionary history of the Y chromosome in relation to the Paris drive, we sequenced 21 iso-Y lines, each carrying a Y chromosome from a different location. Among them, 13 lines carry a Y chromosome that is able to counteract the effect of the drivers. Despite their very different geographical origins, all sensitive Y’s are highly similar, suggesting that they share a recent common ancestor. The resistant Y chromosomes are more divergent and segregate in 4 distinct clusters. The phylogeny of the Y chromosome confirms that the resistant lineage predates the emergence of Paris drive. The ancestry of the resistant lineage is further supported by the examination of Y-linked sequences in the sister species of D. simulans, D. sechellia and D. mauritiana. We also characterized the variation in repeat content among Y chromosomes and identified two simple satellites ((AAACAAT)n and (AATGG)n) associated with resistance. Altogether, the molecular polymorphism allows us to infer the demographic and evolutionary history of the Y chromosome and provides new insights on the genetic basis of resistance.
Dr. Molly Stanely University of Vermont Chacterizing a unique subset of taste cells in Drosophila melanogaster All animals must continually make important feeding decisions. Chemosensory neural circuits, such as those for taste and smell, play a key role in directing feeding behaviors. The sensing of food chemicals by specialized sensory taste cells (gustation) helps animals evaluate potential food sources to encourage consumption of nutritive compounds while avoiding potentially harmful compounds. While the cellular and molecular mechanisms for encoding some taste modalities are relatively well-understood, such as ‘sweet’ and ‘bitter’, other taste modalities are more complex, such as ‘salty’ and ‘umami’. The fruit fly, Drosophila melanogaster, offers unparalleled genetic tools to answer neurobiological questions and I have recently used this model organism to help uncover the molecular and cellular mechanisms of salt taste and feeding. While creating a comprehensive map of taste cells on the fly labellum for this project, a unique subset of chemosensory cells with an unknown function were identified. In this seminar, I will share recent work that aims to characterize the activation profile of these taste cells and understand the functional impact of these sensory cells on feeding behaviors.
Gut microbes help mitigate a major challenge of hibernation Hibernation’s hallmark trait is a profound depression of metabolism that enables animals to survive long periods without eating. This makes hibernation an effective solution to winter’s food scarcity problem; however, it deprives the animal of dietary nitrogen, which is an essential building block for protein. In theory, this should threaten the structure and function of important tissues within the animal, but it has long been known that hibernating mammals avoid this fate and maintain tissue function (e.g., muscle performance) even after many months of fasting hibernation. In this talk, I will discuss our recent work that has revealed how the hibernator’s gut microbes facilitate this tissue preservation and our current work that is investigating how this process may benefit human spaceflight and human health generally.
Accelerating freshwater restoration science & practice through community-engaged research The UN Decade of Ecosystem Restoration (2021-2030) calls for an accelerated need to cooperate at local and global scales to heal our degraded planet, and that the best examples of restoration success have been community-led. Through research situated in watersheds impacted by settler-dominated agricultural intensification and urbanization, Dr. Febria will describe how farm-focused and Indigenous-led partnerships have led to richer outcomes in addition to Western-science outcomes, all of which are crucial for freshwater restoration science and its’ translation into practice and decision-making. Research on molecular and microbial properties of headwater stream ecology and community ecology of Unionid species-at-risk will be discussed as examples of how projects in the Healthy Headwatesrs lab centre human dimensions to inform the science pursued across watersheds in the Laurentian Great Lakes and our shared home known as Turtle Island/North America. Drawing on additional examples globally, this talk will demonstrate how ethical and equitable research partnerships can support a more effective and actionable science, in support of a just and sustainable freshwater future.
Dr. Edel Pérez-López Département de Phytologie, Université Laval Strawberry-leafhopper-phytoplasma, a pathosystem under siege by climate change Food security is threatened by climate change, directly through the response of crop productivity, and indirectly through the relationship of crops with plant pathogens and pests. In Quebec, strawberry growers have been noticing how in the last few years the number of insect pests have been increasing every summer, especially leafhoppers, members of the family Cicadellidae known vectors of virus and bacterial diseases. To understand these observations, we have been investigating for two years the diversity and abundance of leafhoppers in strawberry fields in the main producer areas of the province. In parallel, we have been also investigating the presence and distribution of strawberry green petal disease, a disease caused by bacterial pathogens transmitted by leafhoppers, and the role of those insects as vectors of the disease. In this seminar I will present the results of these two years of work finding an unexpected diversity of leafhoppers including eleven new reports for East Canada, an increase spread of strawberry green petal disease in Quebec fields, and evidence that new pathogens might be affecting soon strawberry fields in Canada, all this probably orchestrated by global warming.
Jeffrey Dason, Department of Biomedical Sciences, University of Windsor Activity-dependent cholesterol redistribution is required for synaptic growth Synaptic plasticity is a fundamental property of neurons that allows their ability to transmit information to change with experience. Numerous studies have examined how synaptic plasticity is regulated by protein–protein interactions and changes in the expression and activation of various proteins. In contrast, the roles of lipids in synaptic plasticity have been less studied. Increasing evidence suggests that the lipid content of neuronal membranes does not remain constant and is altered by synaptic activity. The Drosophila larval neuromuscular junction is a well-established model system for studying synaptic growth and shares the basic molecular components found at most synapses. We generated transgenic flies that express the cholesterol binding D4H domain of Perfringolysin O toxin fused to GFP and found increased levels of cholesterol in presynaptic terminals of glutamatergic Drosophila neuromuscular junctions following periods of increased synaptic activity. We found that cholesterol is required for both synaptic growth and activity-dependent synaptic growth. Examination of several mutant and transgenic larvae reveal that cholesterol is likely regulating synaptic growth through the cAMP-PKA kinase signaling pathway. Collectively, our data demonstrates that cholesterol redistribution occurs in response to synaptic activity and that it plays a key role in development and activity-dependent synaptic plasticity.
Dr. Ben Freeman University of British Columbia, Biodiversity Research Centre Why do tropical species live in narrow slices of mountainsides, and why does this matter in the climate change era? Why do tropical species live in narrow slices of mountainsides? Climate is the prevailing explanation for this pattern, but competition can also restrict species’ elevational ranges. In this talk I will share my research investigating the biogeography of climate change and the relative role of climate and species interactions in shaping species’ ranges in tropical mountains, Earth’s hottest biodiversity hotspots.
Visit Dr. Freeman's website here Dr. Michael Downey University of Ottawa, Faculty of Medicine New functions and regulation for inorganic polyphosphates across evolution Polyphosphates (polyP) are long chains of inorganic phosphates that are found in virtually all cells on earth. Ranging from 3 to thousands of residues in length, these chains have been implicated in diverse functions, ranging from protein folding and virulence in bacteria to cell signalling and blood clotting in higher eukaryotes. How does such a simple molecule participate is such varied functions? I will present our work suggesting that polyP functions, at least in part, via lysine polyphosphorylation. This appears to be a non-enzymatic modification wherein long chains of polyP are thought to be covalently attached to lysine residues of target proteins in bacteria, yeast, and human cells. I will also present evidence that eukaryotic cells tightly regulate polyP subcellular localization, which has important implications for the control of polyphosphorylation and other aspects of polyP biology.
Dr. Downey's CV is viewable here CRISPR-Cas9 based gene editing strategies for the correction of genetic disorders Congenital genetic defects are the leading cause of morbidity and mortality. Despite advances in our understanding of the etiology and pathophysiology of genetic diseases, treatments are lacking. Advances in precision medicine, specifically gene therapy and editing approaches, have provided hope for a cure for these diseases at their molecular roots and can help in improving pathological outcomes. Based on the route of administration, time of delivery (prenatal or postnatal) and type of vectors (viral vectors and nanoparticles), different cell types and tissues can be targeted. In this talk, I will discuss nanoparticle-mediated gene editing (including base editing) strategies for the treatment of diseases such as type 1 tyrosinemia.
Connect with Dr. Sign on Twitter, LinkedIn, or view his publication on Google Scholar Dr. Thomas A. DeFalco Western University Deciphering and engineering kinase-mediated responses to stress in plants Plants must constantly survey their environment to respond to environmental perturbations. Toward this end, plants deploy receptor kinases (RKs) at the cell surface, which allow them to sense and respond to external cues while coordinating growth and development. Many RKs have been characterized as pattern recognition receptors (PRRs), which activate pattern-triggered immunity (PTI) upon perception of non- or altered-self elicitor molecules. Intensive study of model PRRs and PTI has led to an emerging paradigm wherein activated RK complexes trigger downstream signalling via activation of cytosolic kinases. These kinases in turn function to execute downstream signalling through the direct phosphorylation and regulation of diverse substrate proteins. I will discuss our work using a key immune-regulating kinase as a molecular probe to resolve the PTI signalling pathway, as well as how such knowledge can be applied to engineer immune responses. I will also discuss how such approaches may be applied to other, non-immune pathways, and how this relates to specificity in cell signalling.
Dr. Ivan Oresnik Department of Microbiology, University of Manitoba Relationship between central carbon metabolism and nitrogen fixation in Sinorhizobium meliloti Carbon metabolism is generally well understood in Sinorhizobium meliloti. The literature is consistent with the role of dicarboxylic acid metabolism while the bacteroid is actively fixing nitrogen. However, the literature contains many nitrogen fixation phenotypes ascribed to mutants that encode enzymes in central carbon metabolism that make little sense, or are even paradoxical. For example, a mutation in pckA, which is necessary for gluconeogenesis and encodes phosphoenolpyruvate carboxy kinase, consistently gives nitrogen fixation rates that are approximately 50% of wild-type, yet no measurable enzyme activity can be detected in bacteroids. Similarly, our work has shown strains that do not have triose phosphate isomerase activity also yield plants with 50% dry matter accumulation when grown under nitrogen deficient conditions. To date there is no clear explanation why these lesions affect nitrogen fixation based on our current knowledge. Based on our observations, we are hypothesizing that carbon metabolism may be correlated with endoreplication during bacteroid development and that rates of nitrogen fixation may be linked to the copy number of genes directly involved in nitrogen fixation. Although this may explain what occurs in indeterminate nodules, it probably does not apply to determinate nodules, suggesting that what limits nitrogen fixation between these nodule types may be different. Dr. Megan Bontrager Department of Ecology & Evolutionary Biology at University of Toronto Local adaptation at range edges and under anomalous climates Species’ geographic ranges are limited on the landscape. A major focus of work in the Bontrager lab is identifying which evolutionary and ecological forces interact to shape species’ geographic distributions and limit adaptation. In addition, populations are frequently adapted to their local environments, and my lab works to identify which components of the environment are the most important factors driving local adaptation. I will talk about how gene flow affects range edge populations and how these effects may be especially important under climate change. I will also present results from two quantitative syntheses of transplant experiments to 1) examine how climate change is altering patterns of local adaptation, 2) evaluate the relative importance of temperature and precipitation to local adaptation and 3) examine how the magnitude of local adaptation changes from range centres to range edges. This work explores critical drivers of plant population performance and characterizes patterns of adaptation across species' ranges.
Dr. Anusha Shankar Lab of Ornithology at Cornell University Hot and cold hummingbirds: The ecology, physiology and genes of cold endotherms Information about Dr. Anusha Shankar here
Hummingbirds live fast. They have among the highest metabolic rates of all vertebrates, and must eat constantly to stay alive. I will talk about some of what I have learned about how they manage their energy budgets during the day, and how they allocate time and energy to different activities based on changes in their environment. At night, they save energy by entering the fascinating hibernation-like state of torpor. How do they manage to get so cold (~50°F/10°C) and slow their metabolism down as much as they do, and stay alive? This is what I am currently working on finding out. My work integrates methods and approaches from ecology, physiology and transcriptomics to understand how these tiny endotherms manage to survive in a variety of environmental conditions. Dr. Tom Sherratt Carleton University Not all who wander are lost: exploration-exploitation dilemmas, and how animals resolve them There is frequently a trade-off between gaining new information (exploration) and using current information (exploitation). In some instances, this trade-off is mundane: should we play it safe and buy a familiar brand of wine we know is good (exploit), or take a risk and try a new brand that might be even better (explore)? In other instances, the trade-off is a matter of life and death: at what point in a clinical trial should researchers exploit their available information and switch all patients to an experimental drug if it looks like it works? Likewise, non-human animals regularly face exploration-exploitation dilemmas that have fitness consequences: should they attack an unfamiliar type of prey in the hope that it is edible (explore), or trust their instincts and leave it alone (exploit)? Should they continue to graze in the current field, or move elsewhere where the grass may be greener?
In this talk, I highlight the ubiquity of exploration-exploitation dilemmas and introduce the analytical and numerical techniques to solve them. Once the solutions are described, I show how many widely observed phenomena, from age-dependent neophobia in great tits to polymorphisms in butterflies, can be understood as a consequence of animals seeking to resolve this trade-off. The solution techniques to exploration-exploitation models are computationally demanding, and animals cannot possibly solve them by “doing the math”. Indeed, I describe experimental evidence showing how simple “rules of thumb” are able to predict the behaviour of decision-makers far better than the exact solution. Finally, I show how two separate Bayesian approaches to decision making in behavioral ecology, namely signal detection models (which predict strategic behaviour assuming complete information) and exploration-exploitation models (which predict strategic behaviour as information is gained), are deeply connected, with the former a special case of the latter. Dr. Eve Marder
University Professor Victor and Gwendolyn Beinfield Professor of Biology Perturbations Reveal that Degenerate Circuits Hide Cryptic Individual Variability More than 40 years of work on the crustacean stomatogastric nervous system on the cardiac sac, gastric mill, and pyloric rhythms have described numerous instances of circuit reconfiguration by neuromodulation and sensory inputs. These reconfigurations can involve alterations in the frequency and phases relationships of rhythms, and switching of neurons from participating in one circuit to another. Computational works shows clearly that there are multiple, degenerate sets of parameters that can result in similar output patterns. Motivated by this, we have studied the effects of several different perturbations on STG networks, revealing animal-to animal differences in their responses that are not evident without extreme perturbation. Short Biography of Eve: Eve Marder is the Victor and Gwendolyn Beinfield University Professor at Brandeis University. She obtained a B.A degree from Brandeis University in 1969, a Ph.D. from the University of California, San Diego in 1974, and did postdoctoral research at the University of Oregon and the Ecole Normale Superieure in Paris, France before assuming her faculty position in 1978. Marder was President of the Society for Neuroscience (2008), and on the NINDS Council, National Academy of Sciences Council, numerous Study Sections, and Advisory Boards for institutions in the USA and abroad. Marder is a member of the National Academy of Sciences, the National Academy of Medicine, the American Academy of Arts and Sciences, and Fellow of the Biophysical Society, the American Physiological Society, and the American Association for the Advancement of Science. She received the Miriam Salpeter Memorial Award for Women in Neuroscience, the W.F. Gerard Prize from the Society for Neuroscience, the George A. Miller Award from the Cognitive Neuroscience Society, the Karl Spencer Lashley Prize from the American Philosophical Society, Honorary Doctorates from Bowdoin College and Tel Aviv University, the Gruber Award in Neuroscience, the Education Award from the Society for Neuroscience, the Kavli Award in Neuroscience. and the National Academy of Sciences Award in Neuroscience. Marder served on the NIH working group for the Obama BRAIN Initiative, and is now on the BRAIN advisory Council. Marder has served on many journal editorial boards. She was Editor-in Chief of Journal of Neurophysiology, and was a Senior and then Deputy Editor at eLife for its first 6 years. Marder studies the dynamics of small neuronal networks, and her work was instrumental in demonstrating that neuronal circuits are not “hard-wired” but can be reconfigured by neuromodulatory neurons and substances to produce a variety of outputs. She combines experimental work with insights from modeling and theoretical studies. With Larry Abbott, her lab developed the programmable dynamic clamp. Her lab pioneered studies of homeostatic regulation of intrinsic membrane properties, and stimulated work on the mechanisms by which brains remain stable while allowing for change during development and learning. Marder now studies how similar network performance can arise from different sets of underlying network parameters, with its relevance for differential resilience in the population. In addition to her original research papers, Marder has published numerous extremely influential review articles which are heavily cited. Additionally, she has published more than 20 short essays relevant to the life of scientists, senior and junior. She has long been an advocate for women, diversity and international representation. Her life was highlighted in a recent book by Charlotte Nassim, MIT Press, 2018 Lessons from the Lobster, Eve Marder’s Work in Neuroscience. Dr. Gregor Fussmann
The Fussmann Lab, McGill University How plankton interacts with the environment – and what happens if it doesn’t As a freshwater and evolutionary ecologist, I study the population dynamics and the evolutionary adaptation of plankton communities. With accelerating climate change, there is a need to understand the ecological and evolutionary responses of complex plankton communities in lakes and oceans. I will present the results of mesocosm experiments that have investigated the effects of rising CO2 and temperature. These factors play a particular role in lake ecosystems because CO2 is taken up by phytoplankton for photosynthesis and changing temperature affects the liquid water phase but also the duration of ice cover. Plankton communities in the wild always interact with their environment, but it is also necessary to gain an understanding of the baseline dynamics that occur when there is “no environment.” In this vein, I will present an alternative experimental approach, which attempts to shut out external environmental factors. In microcosm experiments we explored whether plankton predator-prey cycles can be sustained over long periods of time, as suggested by classical ecological models. Dr. Rebecca Batstone Institute for Genomic Biology, University of Illinois at Urbana-Champaign The complex genetics of symbiotic extended phenotypes in a model mutualism A goal of modern biology is to develop the genotype-to-phenotype (G-P) map, a predictive understanding of how genomic information generates the organismal trait variation present in natural and managed communities. As microbiome research advances, however, it has become clear that many of these traits are governed by genetic variation encoded not only by the host’s own genome, but also by the genomes of myriad cryptic symbionts. Thus many ecologically-important traits, such as plant yield and pathogen resistance in agriculture, are actually symbiotic extended phenotypes, and this recognition adds even more complexity to our conceptions of the G-P map. Here, I present recent work (see bioRxiv links below) examining naturally-occurring genetic variation in 191 strains of the model N-fixing symbiont, Ensifer meliloti, in four association mapping studies. Using this data, I identify three key features of the G-P map that must be accounted for if we want to predict the evolution of symbiotic extended phenotypes: i) genotype-by-environment (G x E) interactions, ii) genotype-by-genotype (G x G) interactions; and iii) symbiotic pleiotropy, whereby loci influence traits not only of their bearer, but also of interacting individuals. I hope to convince you that the identity and function of loci underlying symbiotic extended phenotypes are largely environmentally-dependent, yet we can nonetheless identify universal loci that are likely important in all or most environments, and thus, serve as excellent targets both for genetic engineering and future coevolutionary studies of symbiosis.
bioRxiv links: https://www.biorxiv.org/content/10.1101/2021.08.03.454976v2.full https://www.biorxiv.org/content/10.1101/2021.07.19.452989v2.full |
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