Dr. Steven Brady Professor, Southern Connecticut State University Boulevard of broken frogs: The perils of polluted ponds and life beside the road Human impacts on wild populations are numerous and extensive, degrading habitats and causing population declines across taxa. Residing perhaps in the shadows of climate change, roads and their many contaminants remain a widespread but often overlooked threat to biota, fragmenting landscapes and delivering suites of pollutants to adjacent habitats. In the snowbelt region of North America, deicing salts – used to melt snow and ice on roads and other impervious surfaces – is causing the salinization of many freshwater habitats. There, these added salts join a bevy of other runoff pollutants that threaten environmental health. Simultaneously, roads and their pollutants can act as agents of natural selection. Increasingly, it is becoming clear that road salt and other pollutants are driving population divergence across contemporary timescales. However, the capacity for local populations to adapt to these stressors remains unclear. Here, we consider the effects of road adjacency and road salt exposure on a pair of amphibian species, the spotted salamander (Ambystoma maculatum) and the wood frog (Rana sylvatica), which are found throughout much of North America. At the population level, these two species of spring-breeding amphibians exhibit contrasting responses to polluted roadside ponds. Spotted salamanders show evidence for local adaptation to roadside habitats. Wood frogs present a complex suite of maladaptive traits expressed during aquatic life stages but adaptive traits in terrestrial life stages. For instance, embryonic survival is relatively low for roadside populations yet adults from these populations have increased fecundity and locomotion. Further, recent evidence suggests that temperature has an exacerbating effect on salt toxicity, especially for roadside populations, and that a pair of genes might underlie the differential sensitivity found between populations. Together, this work indicates that exposure to pollution can have complex transgenerational effects, both adaptive and maladaptive, and that life history tradeoffs and potentially negative pleiotropy might mediate these outcomes.
Dr. Celia Symons Professor, University of California - Irving Species interactions in a changing world As the global climate becomes increasingly extreme and variable, society relies on stable ecosystem functioning for irreplaceable resources and services. To understand what nature will look like in a warmer and more variable future, we must be able to forecast how the climate shapes the strength of negative (predation, competition) and positive (facilitation) species interactions. We have good predictions of how climate will change through time, but we have less understanding of how climate change will cause perturbations across ecological networks via changes in species interactions. Species interactions are more fragile than species themselves because they don’t just require the species to be there, they depend on how species behave, their nutritional requirements, and their phenologies. My research group runs a long-term study of lakes in California’s Sierra Nevada Mountains to address the sensitivity of species interactions to spatial and temporal climate variation. Since 2013, we have conducted annual surveys of ecosystem structure, including biomass and community composition of pelagic producers and primary consumers, benthic invertebrates and chemistry in 21 lakes varying in elevation between 2000 and 3200m. Our 11-year survey includes both the wettest and second driest years of the past century, an indication that extreme conditions are occurring more frequently. Our study indicates that climate can magnify or dampen the influence of both bottom-up and top-down perturbations from pollution and non-native species introductions on aquatic ecosystem structure and function.
Dr. Anje Geitmann Professor, McGill University Multi-scale control of structural functionality in plants Plant tissues display structural organization that is intimately related with the specific tissue's functionality. A unique functionality in plants is organ motion. Although plants are not exactly known to move much, many species actuallly have the ability to orient or fold their leaves in order to optimize photosynthesis or ward off herbivores. Leaf actuation is executed by pulvini—joint-like motor organs that operate like hydraulically powered hinges. In the mimosa leaf, pulvini are incorporated at multiple locations in the compound leaf allowing it to rapidly and efficiently fold upon touch. To understand the mechanical principles underlying the execution of the rapid motion, we investigated pulvinus structure at tissue and cell scales. We found that circumferential hoop reinforcements present at various length scales optimize the translation of hydraulic changes into motion. Specialized cell wall structures and epidermis morphologies direct tissue swelling into directed organ shape changes. These findings provide insight into the role of cell wall structure in plant motor strategies, underscore the hierarchical, emergent nature of biomechanical systems, and highlight design principles that can inform the development of biologically inspired soft actuators.
Dr. Paul Grogan Professor, Queen's University What can Biology tell us about our future? Science is the human-constructed process aimed at understanding phenomena in nature, and hence developing sufficient knowledge to be able to make rational, evidence-based predictions. The human species currently finds itself in a severely threatening environmental and social sustainability crisis. What can the science of Biology tell us about our future?
This seminar will focus on applying core foundational biological principles to understanding our civilisation’s current position and future trajectory, and on suggesting appropriate responses that are coupled with an over-arching strategy to help us cope with the profound realities of our fundamental existential predicament. In short, it will attempt to put the science of biology in its larger context to address the following questions: i) Why are we in the current sustainability crisis, and what does the ultimate underlying answer mean for our future?; and ii) How can we best respond to, and cope with, the fundamental existential realisations that arise from acknowledging that answer? Addressing these questions has been a long personal journey for me, and I am looking forward to presenting my latest attempts at answers to the Department – (i.e. to my community of friends and colleagues that have deep and wide expertise in Biology). My central goal in leading this seminar is to get your feedback, and I look forward to a lively and insightful discussion. Dr. Tanja Slotte Professor, Stockholm University Genomic analyses of distyly in Linum reveal convergent evolution at the molecular level Supergenes govern multi-trait balanced polymorphisms in a wide range of systems, yet our understanding of their origins and evolution remains incomplete. The reciprocal placement of stigmas and anthers in pin and thrum floral morphs of distylous species constitutes an iconic example of a balanced polymorphism governed by a supergene, the distyly S-locus. Recent studies have shown that the Primula and Turnera distyly supergenes are both hemizygous in thrums, but it remains unknown if hemizygosity is pervasive among distyly S-loci. As hemizygosity has major consequences for supergene evolution and loss, clarifying whether this genetic architecture is shared among distylous species is critical. We aimed to characterize the genetic architecture and evolution of the distyly supergene in Linum by generating a chromosome-level genome assembly of Linum tenue, followed by the identification of the S-locus using population genomic data. We show that hemizygosity and thrum-specific expression of S-linked genes, including a pistil-expressed candidate gene for style length, are major features of the Linum S-locus. Structural variation is likely instrumental for recombination suppression, and although the non-recombining dominant haplotype has accumulated transposable elements, S-linked genes are not under relaxed purifying selection. Genomic analyses of additional distylous Linum species identify shared presence-absence variation at the S-locus, indicating that hemizygosity in thrums is a general feature of Linum S-loci. Finally, we investigate the genetic causes and genomic consequences of breakdown of distyly, resulting in homostylous species with elevated levels of self-fertilization. Our findings reveal remarkable convergence in the genetic architecture and evolution of independently derived distyly supergenes, and shed new light on the evolution and loss of an iconic floral polymorphism.
Associate Dean, Serving and Engaging Society Assistant Professor, Departments of Community Health and Epidemiology and Continuing Professional Development and Medical Education Research Scholar, Health Law Institute Dalhousie University Faculty of Medicine Rethinking EDIA in 2024 By the end of this session participants will:
Associate Department Head and Associate Professor; Director of Olga Lakela Herbarium, University of Minnesota Duluth Evaluating a drought-driven model for the evolution of obligate asexual reproduction Obligate apomixis -- asexual reproduction by seed, spore, or egg -- has evolved repeatedly across the tree of life, in diverse organisms ranging from animals (such as reptiles, insects, and fishes) to angiosperms and other plants. Despite its many origins, and the intriguing ecological and evolutionary parallels among them, little is known regarding the causes and long-term consequences of this heritable reproductive syndrome. Some studies suggest that drought, or periodic water limitation, could be key to driving the repeated evolution of obligate apomixis. To evaluate the drought hypothesis, my lab is uniting genomic, spatial, environmental, and life history data (across multiple evolutionary and ecological scales), leveraging ferns as a model system. Current estimates indicate that 10–30% of ferns exhibit obligate apomixis, which has evolved repeatedly in xeric and monsoonal environments around the world. Dry environments impose major constraints on plant life histories and the fern life cycle is especially vulnerable. This study is focused primarily on North American desert ferns and integrates reproductive traits (karyotype, gametophyte development, and spore size/number), climate and microhabitat, and phylogenomic data to specifically ask: Does environmental niche predict obligate apomixis or its constituent traits in desert ferns of North America? This work aims to also bridge generational gaps in technical expertise among next-generation researchers for a variety of cutting-edge and classical approaches, thereby stimulating interdisciplinary student-driven research that emphasizes the value and relevance of museum specimens for addressing fundamental biological questions.
Dr. Patricia Gillis, Research Scientist, Environment and Climate Change Canada Are Clams Actually Happy? Using Freshwater Mussel Ecotoxicology to Determine What Threatens an Imperiled Group Native freshwater mussels (Unionidae) are an ecologically important group, although their complex lifecycle leaves them vulnerable to a range of hazards. Over 70% of North American mussel species are either endangered, threatened, or in decline and poor water quality is considered to be one of the key contributors to their global decline. Canada’s Recovery Strategies for freshwater mussel Species at Risk recognize that poor water quality can affect conservation efforts and pose a risk to recovery. However, the identification and remediation of specific threats presents a challenge when extrapolating from single contaminant lab-based bioassays to the health of native mussel populations, especially in areas with complex mixtures of anthropogenic inputs. With the goal of broadening our understanding of which contaminants pose a risk to mussels, laboratory studies with a range of chemicals have been undertaken in parallel with wild mussel health and population assessments in anthropogenically-impacted habitats. This seminar will illustrate the joys and challenges of working with this complex canary by providing examples of studies that combine lab and field investigations. The first example is centered on the heightened sensitivity of early life stage mussels to salt and the threat that road salt-laden winter road runoff poses to mussels. The second example demonstrates how urban influences, including municipal wastewater effluent negatively impact freshwater mussels across multiple levels of biological organization. A final example will touch on the ‘Clam Project’, an Indigenous Community led investigation of freshwater mussels in Alberta’s Oil Sands Region.
Dr. Ian Richter, Postdoctoral Fellow, Blanchfield Lab, Queen's University Using the metabolic theory of ecology and size spectrum modelling to develop predictive stream fish productivity models Secondary production is indicative of the amount of energy available to higher trophic levels and can provide valuable insight into the dynamics of energy transfer within an ecosystem. Fish production incorporates a wide range of key response metrics such as abundance, biomass, growth, and reproduction, into one quantitative metric but requires resource-intensive data for empirical estimation. An alternative approach to evaluating the distribution and transfer of energy within aquatic ecosystems is size spectrum modelling which is reflects the negative scaling relationship between abundance and body size. While many studies have investigated fish productivity, few have evaluated different methods of estimating production or investigated the key drivers of productivity in riverine ecosystems. In this presentation, I present my research that focuses on investigating different approaches to predict the biomass production of stream fish assemblages using the metabolic theory of ecology and size spectrum modeling. More specifically, I test whether the metabolic theory of ecology and published standard production models can provide precise estimates of total stream fish productivity, investigate how a combination of abiotic and biotic variables are related to stream fish productivity in wadeable Ontario streams, and evaluate the effects of stream classification, spatial scale, and sampling design on the key parameters of riverine size spectrum models. Overall, this research demonstrates that published standard fish production models can be used to estimate productivity, that productivity is better predicted by biotic than abiotic variables, and that size spectra models at broad spatial scales can be used to investigate the movement of energy at higher trophic levels in river ecosystems. My research furthers our knowledge on the biomass production of stream fish communities and can serve a wide range of applications, including conservation and management efforts surrounding stream fish communities.
Dr. Ian Strachan, Professor, Department of Geography and Planning, Queen's University Understanding Carbon Cycling in Peatland Systems from Disturbance Through Restoration The operations of the Canadian Horticultural Peat Industry result in a disturbance to the natural carbon (C) functioning of selected peatlands. While the disturbed area is small in comparison to the total peatland area, nonetheless, during the years of active harvesting, these former peatlands are net C sources to the atmosphere. Following the cessation of harvesting operations, for any period left unrestored, the peatlands remain large sources of C to the atmosphere. Post-disturbance, the goal of active restoration is to return C functioning of the disturbed ecosystem to one resembling the pre-disturbance state. If the rewetting and revegetation process is successful in re-establishing conditions like that of an undrained peatland, this means a return to a sink for CO2 and a source of methane but an overall annual sink for carbon.
In this presentation, I provide examples of our Industry-partnered NSERC research where we have for the first time quantified the emissions from partially drained peatlands undergoing active production and have shown that restoration successfully returns the C sink function of peatlands. In the first example, several years of study in an eastern peatland indicated a decay in C emissions through years since harvesting began. We found that this resulted from the increasingly recalcitrant (older) C being exposed as years of harvest continued; a finding that was corroborated by C dating of the peat and measurements of humification. In the second example, the net ecosystem exchange (NEE) of C was continuously measured for multiple years in restored peatlands in eastern and western Canada using the eddy covariance method. We identified small but significant differences in respiration driven by temperature that were responsible for differences in cumulative NEE between years. In both locations, having the soil moisture consistently near the surface was linked to success. After ~15 years post-restoration, the eastern peatland had a mean net ecosystem uptake of 78 ± 17 g C m−2 year−1 which was similar to a reference undisturbed peatland. The more-newly restored western peatland showed greater spatial variation in NEE resulting from differences in soil moisture conditions across the site with wetter locations more closely resembled the NEE of an undisturbed peatland. Combined, all site years allow us to see the resulting restoration trajectory in terms of C function. Finally, through a radiative forcing model, we showed that restoration immediately following the cessation of harvesting operations would result in the restored ecosystem achieving a future net C sink status 7-8 times sooner than would a 20-year delay in restoration. Our results are currently being used to update emissions factors for Canada’s national C inventory. Dr. Dilini Abeyrama, Post-doctoral Fellow, Lougheed Lab, Queen's University Population differentiation of Southern Ocean seabirds The Southern Ocean is a remote but unique ecosystem with high winds, strong currents, and a handful of islands surrounding the Antarctic continent. Reduced gene flow due to these physical and non-physical barriers supports rapid evolution and endemism within the Southern Ocean. Seabirds are a good model to study barrier-mediated speciation as they face a limited number of physical barriers, yet they are a highly diversified group. In my thesis, I used molecular markers to study population differentiation in five Southern Ocean seabird species at the three levels: among ocean basins, within oceans and within a single island. Sooty albatross (Phoebetria fusca) and yellow-nosed albatross showed population differentiation between Atlantic and Indian Ocean basins. Two sister species of yellow-nosed albatross, Atlantic (Thalassarche chlororhynchos) and Indian (Thalassarche carteri), both showed population genetic structure within Atlantic and Indian Oceans, respectively. The other two study species, Kerguelen shags (Phalacrocorax verrucosus) and gentoo penguins (Pygoscelis papua) breeding on Kerguelen Island, showed genetic structure among different breeding colonies of each species on the same island. Non-physical barriers such as natal philopatry and at-sea distribution, are limiting gene flow in the Southern Ocean at different geographic scales.
Dr. Amanda Grusz, Assistant Professor, University of Minnesota Duluth Evaluating a drought-driven model for the evolution of obligate asexual reproduction Obligate apomixis -- asexual reproduction by seed, spore, or egg -- has evolved repeatedly across the tree of life, in diverse organisms ranging from animals (such as reptiles, insects, and fishes) to angiosperms and other plants. Despite its many origins, and the intriguing ecological and evolutionary parallels among them, little is known regarding the causes and long-term consequences of this heritable reproductive syndrome. Some studies suggest that drought, or periodic water limitation, could be key to driving the repeated evolution of obligate apomixis. To evaluate the drought hypothesis, my lab is uniting genomic, spatial, environmental, and life history data (across multiple evolutionary and ecological scales), leveraging ferns as a model system. Current estimates indicate that 10–30% of ferns exhibit obligate apomixis, which has evolved repeatedly in xeric and monsoonal environments around the world. Dry environments impose major constraints on plant life histories and the fern life cycle is especially vulnerable. This study is focused primarily on North American desert ferns and integrates reproductive traits (karyotype, gametophyte development, and spore size/number), climate and microhabitat, and phylogenomic data to specifically ask: Does environmental niche predict obligate apomixis or its constituent traits in desert ferns of North America? This work aims to also bridge generational gaps in technical expertise among next-generation researchers for a variety of cutting-edge and classical approaches, thereby stimulating interdisciplinary student-driven research that emphasizes the value and relevance of museum specimens for addressing fundamental biological questions.
Dr. Catherine Cullingham, Assistant Professor, Carleton University Using the mountain pine system to demonstrate the use of genomics to understand risk and resiliency of forests to large scale disturbances Mountain pine beetle has had significant impacts in western Canadian pine forests over the past two decades. Over 20 million hectares of pine in Canada has been affected impacting industry, communities, carbon cycling and ecosystem function. In 2006 the beetle expanded into central Alberta where it has encountered a novel host, jack pine. Many questions have arisen since then including, is jack pine an appropriate host for mountain pine beetle? What is the potential for continued spread across the Boreal forest? What genes underlie host susceptibility? Using population genetics, spatial ecology, and molecular biology my lab helps to answer some of these important questions, and provide useful outputs for management and predictive modelling. Through this integrated approach we provide insights into whether jack pine is a suitable host for mountain pine beetle which is an important step towards understanding the spread-risk potential of the beetle. We also have begun to identify the genetic component of pine host resilience to mountain pine beetle. Given the increasing frequency and intensity of biological invasions in forest ecosystems, approaches that consider interactions from the landscape to the individual will be critical for ensuring forest resiliency in the future.
Dr. Paulo Teixeira, Professor at "Luiz de Queiroz" College of Agriculture, University of São Paulo Nonhost plants as a source of immune receptors against pathogens of agricultural importance Plants use NLR receptors to detect effectors from pathogens and activate defense responses. However, most immune receptors in the plant kingdom remain uncharacterized, especially those in nonhost plants that are resistant to a wide range of pathogens of agricultural importance. Here, we examined whether nonhost Solanaceae species can recognize effectors from the citrus pathogen Xanthomonas citri subsp. citri. We transiently expressed 22 effectors in tomato, eggplant, Nicotiana benthamiana and N. tabacum and found that these nonhost plants recognized a distinct, but overlapping, set of effectors. Interestingly, XopAZ was recognized by all species, indicating the presence of conserved NLR receptors that respond to this effector. We subsequently identified a novel pair of TIR-NLRs in Solanaceae that is required for XopAZ recognition. I will discuss how this approach may facilitate the identification of immune receptors that could be transferred to crops as a strategy to combat diseases.
Maureen Buchanan is an Anishinaabe Kwe, a member of the local urban Indigenous community of Kingston and a member of the Batchewana First Nation near Sault Ste. Marie. Maureen has lived in Kingston for 30 years and raised her family. She, like many others in her community, through volunteerism, has worked to create small spaces of urban indigenous visibility, community connectedness, cultural sharing and language learning. She is a founder of the Kingston Indigenous Languages Nest and a founding director of the All Our Relations Land Trust. The talk will describe a local land-based project in which urban Indigenous people and allies have put into practice an evolving practice of land stewardship based on a worldview of sacred relations with our ecological kin and informed by Western science. Given the twin crises of biodiversity loss and climate change, Maureen will discuss the actions of this group of volunteers over the last three years and what actions are on the horizon.
Dr. Paulo Teixeira, Professor at "Luiz de Queiroz" College of Agriculture, University of São Paulo Nonhost plants as a source of immune receptors against pathogens of agricultural importance Plants use NLR receptors to detect effectors from pathogens and activate defense responses. However, most immune receptors in the plant kingdom remain uncharacterized, especially those in nonhost plants that are resistant to a wide range of pathogens of agricultural importance. Here, we examined whether nonhost Solanaceae species can recognize effectors from the citrus pathogen Xanthomonas citri subsp. citri. We transiently expressed 22 effectors in tomato, eggplant, Nicotiana benthamiana and N. tabacum and found that these nonhost plants recognized a distinct, but overlapping, set of effectors. Interestingly, XopAZ was recognized by all species, indicating the presence of conserved NLR receptors that respond to this effector. We subsequently identified a novel pair of TIR-NLRs in Solanaceae that is required for XopAZ recognition. I will discuss how this approach may facilitate the identification of immune receptors that could be transferred to crops as a strategy to combat diseases.
Dr. Benjamin Martin, Post-doctoral fellow, Harvard University Global identification of SWI/SNF targets reveals compensation by EP400 Mammalian SWI/SNF chromatin remodeling complexes move and evict nucleosomes at gene promoters and enhancers to modulate DNA access. Although SWI/SNF subunits are commonly mutated in disease, therapeutic options are limited by our inability to predict SWI/SNF gene targets and conflicting studies on functional significance. Here, I will describe our recent results where we have leveraged a fast-acting inhibitor of SWI/SNF remodeling to elucidate the direct targets and effects of SWI/SNF. We find that blocking SWI/SNF activity causes a rapid and global loss of chromatin accessibility and transcription. Whereas repression persists at most enhancers, we uncover a compensatory role for the EP400/TIP60 remodeler, which reestablishes accessibility at most promoters during prolonged loss of SWI/SNF. Indeed, we observe synthetic lethality between EP400 and SWI/SNF in cancer cell lines and human cancer patient data. Our data define a set of molecular genomic features that accurately predict gene sensitivity to SWI/SNF inhibition in diverse cancer cell lines, thereby improving the therapeutic potential of SWI/SNF inhibitors.
Dr. Jacqueline Sztepanacz, Assistant Professor, University of Toronto The evolution of sexual dimorphism over micro- and macro-evolutionary timescales The largely shared genome of males and females leads to genetic covariances between their shared traits. These genetic covariances can have a large effect on the magnitude and distribution of genetic variation within and between the sexes, which may lead to evolutionary constraints when the sexes are subject to divergent selection. In this talk, I will share results showing how the evolvability of sexual dimorphism in contemporary populations is correlated to the evolution of sexual dimorphism over millions of years, suggesting that patterns of genetic variation in contemporary populations can lead to long-lasting evolutionary constraints. I will also share recent research from my group investigating how patterns of natural and sexual selection contribute to this process.
Dr. Marc Laflamme, Professor, University of Toronto Mississauga Complexity in the oldest animal communities My research focuses on the Ediacaran Period (635-538 Ma), which represents a pivotal time in Earth history, marked by the transition from single-celled organisms into complex multicellular animals. My interests lie in the natural history and functional morphology of the Ediacara biota, a group of soft-bodied organisms whose affinities are fiercely debated, and whose disappearance from the fossil record prior to the Cambrian explosion of animals is equally perplexing. The geobiological context in which the first animals evolved (and in which the Ediacara biota disappeared) thus represents one of the most crucial transitions in the history of life, incorporating Earth’s first major biotic crisis, as well as its most dramatic evolutionary radiation. I hope to showcase how innovative computational approaches to investigating fossil morphology has led to the discovery of some of the earliest evidence for facilitation and Ediacaran nurseries, while dedicated studies into the decay of soft-tissues has led to novel conclusions surrounding biases in the fossil record of early life.
Dr. Laurence Yang, Assistant Professor, Queen's University Toward precision whole-cell simulators Manufacturing industries find computer simulations to be indispensable: they speed up design, increase product quality, and reduce R&D costs while helping to find alternatives to traditional design methods. Likewise, the bio-manufacturing industry has relied on simulators to model reactors and processes. Increasingly, companies are finding value in simulating the living cell factories themselves (microbes, mammalian cell lines, etc.). We will demonstrate cell modeling with examples from multiple organisms (Pseudomonas, Escherichia coli, algae), and for varying applications (drug discovery, bioproducts, discovery). We discuss modeling of microbial stress responses in the context of antimicrobial resistance. With recent advances in integrated genome-scale models of metabolism and protein expression, we developed a framework to predict microbial response to thermal, oxidative, and acid stresses. The models accurately compute how E. coli changes gene expression and metabolic states in response to these stresses, together with variations in nutrient availability. Furthermore, these models explain the molecular mechanisms underlying improved fitness observed for several microbes that were adaptively evolved under oxidative stress. We then show how the modeling method extends to eukaryotes, using algae as an example.
Dr. Saeid Mobini, Phytotron Facility Manager, Queen's University Revolutionizing Soybean Breeding: Incorporating Speed Breeding Techniques Speed breeding is an innovative agricultural methodology that revolutionizes the traditional plant breeding process by leveraging controlled environments and specialized lighting to accelerate crop growth cycles, significantly shortening the time required to produce successive generations of plants. This cutting-edge technique empowers plant breeders to expedite genetic selection, enhance diversity exploration, and swiftly develop improved crop varieties to address critical global challenges, including food security, climate change, and disease resistance. Speed breeding's adaptability to various crop species has positioned it as a transformative tool in modern agriculture, driving crop improvement and sustainability advancements.
Dr. Tia Harrison, Postdoctoral Fellow, Queen's University Patterns, consequences, and processes of mutualism evolution in the legume-rhizobium system Cooperation between species is widespread in nature yet the circumstances under which
mutualism evolves remain mysterious. My research uses the legume-rhizobium interaction to better understand patterns in mutualism evolution across geographic space, the ecological consequences of engaging in mutualism, and how mutualism evolves at a molecular level. Currently, our understanding of the legume-rhizobium interaction comes from a few well-studied temperate species. My research advances the field of legume-rhizobium research by sampling, sequencing, and analyzing non-model species from other parts of the globe, including the tropics. Legume-rhizobium interactions are greatly influenced by nutrient and partner availability in their habitat. I investigated changes in microbial community assembly on legumes across a large latitudinal gradient to understand how this interaction changes in temperate and tropical habitats. Although legumes hosted similar numbers of rhizobia partners across the range, tropical legumes associated with more non-rhizobia strains suggesting that tropical plants are less choosy of their symbiotic partners. There are many predicted benefits of being a less choosy host or generalist host to many symbiotic microbes. Using meta-analysis methods, I demonstrated that legume hosts that associate with many different rhizobial partners are more likely to find a compatible partner when introduced to a novel habitat. Generalist legumes establish in many new ranges and therefore experience greater ecological success compared to legume species that specialized on only a few rhizobia partners. It is unclear whether or how mutualism effects rates of molecular evolution. Most of the literature is focused on understanding how parasitic interactions are predicted to increase evolutionary rates in interacting species. I generated new sequence data from several non-model mutualistic species and found that mutualistic lineages in plants and rhizobia show elevated rates of molecular evolution. Therefore, mutualists may experience greater genetic change because they adapt to both a changing environment and symbiotic partners. Full Professor, Department of Cellular & Molecular Medicine Faculty of Medicine, University of Ottawa The SMC5/6 complex: Folding chromosomes back into shape when genomes take a break High-level folding of chromatin is a key determinant of the shape and functional state of chromosomes. During normal cell division cycles, structural maintenance of chromosome (SMC) complexes ensure the large-scale folding of chromatin into visible chromosomes. While it is known that cancer cells experience important changes in genome architecture, it is still unclear if mutations in core regulators of chromosome structure can lead to cancer-promoting loss in genome stability. To address this question, we conducted a systematic analysis of mutations affecting a global regulator of chromosome biology –the SMC5/6 complex– in cancer genomics cohorts. Analysis of 64,959 cancer samples spanning 144 tissue types and 199 different cancer genome studies revealed that the SMC5/6 complex is frequently altered in breast cancer patients. Patient-derived mutations targeting this complex associate with strong phenotypic outcomes such as loss of ploidy control and reduced overall survival. Remarkably, the phenotypic impact of several patient mutations can be observed in a heterozygous context, hence providing an explanation for a prominent role of SMC5/6 mutations in breast cancer pathogenesis. Overall, our findings suggest that genes encoding global effectors of chromosome architecture can act as key contributors to cancer development in humans.
Dr. Josh Neufeld, University of Waterloo Professor, University Research Chair Shedding light on the evolution of anoxygenic phototrophy through cultivation of Boreal Shield lake bacteria Phototrophic members of the Chloroflexota phylum are enigmas in the evolution of phototrophy because of their unusual photosynthetic reaction centre and antenna complex pairing. Through a “failed” cultivation experiment from an iron-rich Boreal Shield lake, we recovered and characterized a novel new species, “Ca. Chlorohelix allophototropha”, with unexpected features relevant to the evolution of phototrophic bacteria. This talk will present genome, physiology, and ecology data to demonstrate that this phylogenetically distinct phototroph can be among the most active populations in illuminated anoxic waters of Boreal Shield lakes, which number in the millions globally. Our results establish Chloroflexota phylum members as unique among known anoxygenic phototrophs, providing new context for understanding the origins of phototrophic life on Earth. Dr. Graeme Howe, Assistant Professor Queen's University, Department of Chemistry Genome mining for "extremozymes" - Extremophiles as sources of novel biocatalysts Directed evolution has enabled the development of extremely useful biocatalysts that have, in some cases, supplanted traditional organic chemistry in the industrial production of value-added commodity chemicals. Generally, mutations introduced into a protein scaffold to increase catalytic efficiency are accompanied by a compensatory destabilization of the enzyme. To circumvent this issue and allow a more thorough exploration of sequence space around naturally occurring enzymes, we have turned to sequence similarity networks (SSNs) to mine the genomes of thermophilic microorganisms to identify novel thermostable variants of enzymes with potential industrial utility. These networks allow for the exploration of whole protein families and the interrelatedness of every member sequence through an ‘all-by-all’ BLAST. Through the iterative construction of SSNs with varying sequence identity cutoffs, we have produced networks of putative isofunctional clusters that allow a single sequence with known catalytic function to reveal the role of thousands of unannotated PETase-like genes.
Our initial efforts in this arena have focused on the search for new thermostable plastic-degrading enzymes as a part of the OpenPlastic consortium’s efforts to develop a circular plastics economy. Following the initial discovery of a cutinase-like enzyme from Ideonella sakaiensis that degrades polyethylene terephthalate (PET), there has been an explosion in research revolving around the biocatalytic degradation of PET and other plastics. While several engineered PETases have emerged that are sufficiently stable and catalytically efficient for industrial PET degradation, we opted to direct our initial efforts to exploit the wealth of PETase sequence-function relationships to mine the genomes of extremophiles for new PETases as starting points for further engineering efforts. Using the I. sakaiensis enzyme as a seed sequence, SSNs were constructed that led to the identification of 10 putative PETases from bacteria with optimal growth temperatures ranging from 50 °C to 80 °C. This presentation will detail our efforts to characterize these enzymes and their potential utility in the degradation of PET plastics. Similar bioinformatics-driven approaches to identify and characterize thermostable enzymes that degrade polyamides and polyurethanes will also be presented. |
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