The Departmental I-EDIAA committee will be screening the 30-minute film ‘Signal Fire’. This film progressed out of the working group composed of Canadian scientists and Indigenous elders and scholars that published “Towards Reconciliation: 10 Calls to Action to Natural Scientists Working in Canada” in Facets (Wong et al., 2020).
More information about the film, and its trailer, can be found at: https://www.signalfirefilm.ca/watch Following the screening, everyone is welcome to participate in a discussion (~20 minutes). Those interested will break into small groups (using several rooms on the 3rd floor) and will be provided a few questions to guide reflection and discussion. We look forward to seeing everyone at this screening and discussion. 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. Zoe Kane, PhD Candidate, Smol Lab Using changes in Cladocera assemblages to determine how ornithogenic inputs structure freshwater ecosystems Seabirds can be considered biovectors, transporting large concentrations of nutrients (e.g., nitrogen (N), phosphorous (P)) and metals (e.g., Cd, Zn, Hg) from their marine feeding grounds to their terrestrial breeding grounds. Seabird fertilizes their nesting sites by depositing feces, feathers, carcasses, and eggshells, which can be tracked directly (e.g., sterol/stanol to characterize guano deposits) or from their influence on nearby waterbodies (e.g., nutrient enrichment and/or pH changes traced using subfossil algal assemblages over time). Recent paleolimnological studies from PEARL reconstructed and hindcasted the population dynamics of Baccalieu Islands vulnerable Leach's Storm petrel population (Hydrobates leucorhous, hereafter LESP) to assess the effects of natural and anthropogenic stressors.
Adding to the several paleolimnological proxies used to track and reconstruct historical LESP inputs on ponds on Baccalieu island (Lunin, Brister, Gull and Mainland Reference ponds), I have implemented Cladocerans, or water fleas, which are well-known paleolimnological indicators (but as yet unexplored in these novel ornithological-limnological studies) as their species-specific exoskeletal remains are well preserved in sediment. They have a pivotal role in aquatic food webs, occupying an intermediate trophic position between top-down regulators and bottom-up factors, providing a critical link between the eutrophication process and the implications of elevated nutrient conditions on higher trophic levels. My results build on previous work that examined how seabird-derived nutrients influence primary production and algal assemblages in highly impacted ponds. I demonstrate that shifts from littoral/benthic to pelagic cladoceran taxa coincide with peaks in the inferred LESP population, highlighting the importance of seabird inputs to limnological conditions and eutrophication in several ponds on Baccalieu Island. 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.
Christina M. Tschritter, PhD Candidate, Lougheed Lab Mapping pathogen distributions and population connectivity of a sentinel Arctic species, the polar bear (Ursus maritimus) across a changing North American Arctic Large-scale environmental shifts are expanding pathogen distributions making many northern species more vulnerable to disease. To understand such rapidly changing host-pathogen dynamics and potentially mitigate impacts of novel pathogens on northern peoples and ecosystems, I quantify population connectivity and pathogen presence in a sentinel Arctic species, the polar bear (Ursus maritimus). Polar bears are apex predators that can provide insight into pathogen distribution and prevalence across marine and terrestrial ecosystems. The focus of my dissertation was to develop molecular tools to monitor polar bear populations and to promote co-management through non-invasive and harvest-based sampling. More specifically I aimed to: (i) Delineate polar bear population structure using genome-wide panels of Single Nucleotide Polymorphic markers (SNPs) to interpret population connectivity that might impact pathogen spread; (ii) Develop and validate a sensitive multiplexed, magnetic-capture, and digital PCR tool for surveillance of five zoonotic pathogens (three bacteria Erysipelothrix rhusiopathiae, Francisella tularensis, and Mycobacterium tuberculosis complex (MTBC), and two parasites T. gondii and Trichinella spp.) relevant to wildlife and human health; and (iii) Quantify the spatial distributions of focal pathogens in polar bear tissues and observe associations between pathogen detections and predictors. Despite the mobility of polar bears and their large home ranges I found three population clusters that coincide with Arctic ice ecoregions. I made novel pathogen detections (first detection of E. rhusiopathiae in a polar bear, first molecular detection of F. tularensis in the tundra, and the first detection of a MTBC member in Arctic wildlife) and provide insights on how populations might respond to future exposure to novel pathogens. Overall, we found that harvest season and human settlements were important predictors of presence for some pathogens. I envision the establishment of a long-term harvest-based monitoring program that incorporates the powerful molecular tools that we have created, enabling territorial governments to monitor changes in prevalence and/or the geographic advance of select pathogens. The continuation and expansion of this work into a monitoring program would present an unprecedented opportunity to provide critical, real-time, and community-based disease surveillance across the Arctic and ultimately improve opportunities for the co-management of the polar bear species.
Rui Huang, PhD Candidate, diCenzo Lab and Snedden Lab Characterizing the functional impact of Sinorhizobium meliloti bacA allelic variation on symbiosis with legume hosts The symbiosis between legume plants and rhizobial bacteria are highly specific and require both partners to be compatible with each other during the process of symbiotic development. A range of host and symbiont properties regulate the specificity of these relationships. In certain clades of legume plants, the rhizobial BacA transporter and legume-expressed NCR peptides are thought to play a role in defining host/symbiont compatibility. The inverted repeat-lacking clade (IRLC) of legumes expresses NCR peptides to initiate and maintain terminal differentiation of rhizobia, a developmental process that leads to mature, nitrogen-fixation bacteroids. The BacA transporter is essential in transporting NCR peptides and protecting the rhizobia from the antimicrobial activity of these peptides. A previous study found that replacing the bacA allele of Sinorhizobium meliloti with the ortholog from Rhizobiumleguminosarum allowed symbiosis with the host Melilotus officinalis but not with Medicago sativa. In this thesis, I investigated the mechanisms underlying the symbiotic specificity of bacA alleles. On the host legume side, the nodule transcriptomes of M. sativa and M. officinalis were assembled, and their NCR peptide transcripts were identified. The transcriptomic data revealed an approximately 2-fold greater abundance of transcripts encoding highly cationic NCR peptides (isoelectric point > 9.5), which are known to have antimicrobial properties, in M. sativa vs M. officinalis. I hypothesize that the difference in the abundance of highly cationic NCR peptide contributes to why the R. leguminosarum BacA can support symbiosis with M. officinalis but not M. sativa. In addition, I hypothesize that unlike the S. meliloti BacA, the R. leguminosarum BacA is unable to efficiently transport all of the highly cationic NCR peptides of M. truncatula, resulting in a build-up in the bacterial periplasm, leading to cell death. On the rhizobia side, I combined genetic analysis and computational modelling to better understand the BacA transporter. Site-directed mutagenesis analyses showed that S. meliloti
Q193G and N312G BacA mutants recreated the symbiotic phenotypes of S. meliloti carrying the R. leguminosarum bacA allele when paired with hosts M. sativa and M. officinalis. In addition, I generated mutant libraries of S. meliloti and R. leguminosarum bacA through error-prone PCR that identified amino acid residues important for BacA function. Together with BacA structural models that I generated, these data provide novel insight and hypotheses into the functional differences between S. meliloti and R.leguminosarum BacA and their ability to transport NCR peptides. Collectively, the data presented in this thesis provides a deeper understanding of how BacA and NCR peptides may contribute to host/symbiont compatibility in rhizobium – legume symbioses. 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.
AAKANX PANCHAL - MSc Candidate Tackling the rhizobium competition problem by engineering exclusive compatibility between legumes and inoculant rhizobia Legume plants can benefit tremendously from their relationship with nitrogen-fixing soil bacteria called rhizobia. Within structures rhizobia induce along legume roots called nodules, rhizobia fix atmospheric dinitrogen into ammonia. High nitrogen-fixing rhizobium inoculants can provide legume crops with enough bioavailable nitrogen under ideal conditions to limit nitrogen fertilizer use and its negative environmental impacts. However, low nitrogen-fixing rhizobia native to the soil can outcompete high nitrogen-fixing rhizobia for nodule occupancy, reducing the benefit to the legumes and ultimately perpetuating dependence on nitrogen fertilizer. A potential solution to this "rhizobium competition problem" is engineering exclusive compatibility at the level of nodule occupancy between high nitrogen-fixing rhizobium inoculants and their associated legume crops. Nodule occupancy begins with rhizobia producing Nod factors specific to legume Nod factor receptors, where Nod factors and Nod factor receptors are like keys and locks. It is the ability of low nitrogen-fixing rhizobia native to the soil to produce the same Nod factors as high nitrogen-fixing rhizobium inoculants that allows low nitrogen-fixing rhizobia to nodulate the legume. Exclusive compatibility between the rhizobium inoculant and legume crop would involve inoculant rhizobia producing Nod factors that are unique in the target environment and legumes producing matching Nod factor receptors, such that low nitrogen-fixing rhizobia producing the original Nod factors should no longer be able to nodulate the legume. To test the feasibility of using this strategy, we have been working towards genetically engineering a model rhizobium-legume pair, Sinorhizobium meliloti and Medicago truncatula, to use Nod factors and Nod factor receptors from a different rhizobium-legume pair, Mesorhizobium japonicum and Lotus japonicus. In my seminar, I will present our progress in bringing the Lotus japonicus Nod factor receptor genes together into a single construct for their eventual expression in Medicago truncatula.
MSc Candidate, Aristizabal Lab Understanding the regulation and function of Cdk8 Cdk8 is a conserved protein kinase and a member of the Mediator transcription co-activator complex. Accumulating evidence highlights Cdk8 as a crucial oncogene in colorectal cancer, emphasizing the need to understand its function and regulation. Notably, CDK8 is amplified or overexpressed in approximately 60% of colon cancer tumors, and elevated CDK8 levels correlate with tumor stage and reduced patient survival. Supporting its oncogenic role, knockdown of CDK8 diminishes the proliferation of colon cancer cell lines, while overexpression induces tumor formation in immunodeficient mice, effects that depend upon Cdk8's kinase activity. Beyond colorectal cancer, growing research also implicates CDK8 in melanoma, leukemia, as well as breast, pancreatic, and prostate cancer, evidence that has stimulated the development of Cdk8 inhibitors for cancer therapy. Despite a growing interest to target Cdk8 for anti-cancer treatment we have limited information about Cdk8 regulation, a knowledge gap that may complicate efforts to block its activity. For my exit seminar, I will discuss my work using the budding yeast model system to understand the function and regulation of Cdk8 by leveraging disease-associated variability and recent insight from structural and biochemical analyses. Specifically, I have leveraged data from The Cancer Genome Atlas and ClinVar to identify CDK8 missense mutations that are likely to affect function. This work led me to find a cluster of mutations that localize to the kinase ATP binding pocket or sites of interaction with CycC and Med12, proteins known to regulate Cdk8 kinase activity. My findings so far suggest that most of the mutants disrupt Cdk8 function, resulting in a feedback mechanism that leads to an increase in Cdk8 protein and mRNA levels. In addition, my work examining the role of Med12 in regulating Cdk8’s activity in vivo showed that this interaction contributes to Cdk8 function in a condition specific manner. Collectively, this research sheds light on the function and regulation of Cdk8, work that will inform the development of targeted therapies and enhance our understanding of the mechanisms by which Cdk8 contributes to cancer development.
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.
MSc Candidate, Lougheed Lab Mapping the Contact Zone of Two Chorus Frog Mitochondrial Lineages in Southern Ontario Contact zones facilitate the study of diverging evolutionary lineages in primary (evolved in situ) or secondary (evolved in allopatry) contact; outcomes of contact zone dynamics have implications for species range limits, can clarify questions regarding species delineation and speciation itself, and may be relevant for conservation. Chorus frog populations within Ontario and Quebec (currently collectively classified as Pseudacris triseriata) possess distinct mitochondrial haplotypes representing Boreal (P. maculata) and Western Chorus Frogs (P. triseriata). These diverging mitochondrial lineages are in secondary contact in Southern Ontario, yet the exact location of contact is uncertain, lying somewhere between Toronto and southern Georgian Bay (a linear span of ~150km). I used environmental DNA (eDNA) from water sampled at ~50 chorus frog breeding ponds to better delineate the chorus frog contact zone. Environmental DNA facilitates extensive geographic sampling, allows for the identification of single wetlands with co-occurring populations, and is less invasive than tissue sampling (e.g. toe clipping, buccal swabbing, lethal sampling). I used droplet digital PCR with custom primer-probe mitochondrial cytochrome b sets that target each lineage (one primer-probe set for each lineage). My data refine the location of the contact zone and identify at least three ponds with both lineages present. My findings set the stage for future work in hybridization and speciation, and have implications for conservation and designations by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). My research also showcases the effectiveness of eDNA in mapping the distributions of cryptic or secretive species or evolutionary lineages.
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.
Troy Martin, MSc Candidate, Arnott Lab Effects of 'eco-friendly' road de-icer alternatives on freshwater ecosystems Increasing use of de-icing salt on roads and paved surfaces is contributing to rising salinity in freshwater, threatening aquatic ecosystems. In response, novel road de-icers advertised as “eco-friendly” have been developed and are widely used in large cities across North America. Despite this, research on road salt alternative toxicity rarely extends beyond individual species, and community and ecosystem-level testing remain limited. We used outdoor mesocosms to test how zooplankton communities, important primary consumers in aquatic systems, responded to three de-icers: rock salt (NaCl), an organic alternative (beet-brine), and an inorganic alternative (NaCl, CaCl2, MgCl2). We found that both alternatives were toxic to zooplankton and decreased total abundance and richness of communities. Cladocerans and copepods were more sensitive than rotifers for all de-icers, indicating differential sensitivities that would impact community composition, species interactions, and ecosystem function. We further saw impacts at the zooplankton species level and at the bacterial community level, indicating that de-icers might have impacts at various trophic levels. These results are worrisome because they suggest that some de-icer alternatives might not be as “eco-friendly” as advertised, despite their growing use across North America.
Emma Graves, PhD Candidate, Smol Lab Assessing long-term anthropogenic impacts on lakes within the Rideau Canal system: A paleolimnological assessment The Rideau Canal was constructed in the early-1830s, primarily as a means to transport military personnel, but is now exclusively recreational. The construction of the canal and associated flooding, as well as other land-use changes, likely impacted lakes within the system, but long-term monitoring data are not available. Furthermore, recent environmental changes, including accelerated climate warming, have likely affected lake ecosystems. Paleolimnology can be used to reconstruct these missing data sets. Earlier diatom-based paleolimnological studies were conducted on lakes within the Rideau Canal system ~25-30 years ago and more recently by K. Balasubramaniam (MSc, 2022). However, nothing is known concerning the long-term changes in primary consumer (i.e., Cladocera) assemblages linked to the various environmental disturbances. Using the biological information stored in dated sediment profiles from five lakes within the Rideau Canal system (Opinicon, Upper Rideau, Lower Rideau, Big Rideau, and Indian), my study examines how cladoceran assemblages have changed over the past ~250 years in response to these multiple environmental stressors. Changes linked to canal construction and subsequent flooding are recorded in the sediment profiles. However, the most striking shifts in both diatoms and Cladocera have occurred since the 1970s, with assemblage changes linked to accelerated climate warming. These changes will likely have cascading effects on other ecosystem services.
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.
Millie Smith, MSc Candidate, Plaxton Lab Phosphorylation of the cytosolic glucose-6-phosphate dehydrogenase isozyme AtG6PD6 in response to phosphate nutrition of the model plant Arabidopsis thaliana Glucose-6-phosphate dehydrogenase (G6PD) is a tightly regulated enzyme that catalyzes the first committed step of the oxidative pentose phosphate pathway (OPPP). The OPPP plays a pivotal role in generating reducing power in the form of NADPH, and carbon skeletons (e.g., ribose-5-P) needed for anabolism and cell growth. Our recent phosphoproteomics study discovered that the cytosolic G6PD isozyme, AtG6PD6, became hyperphosphorylated at multiple N-terminal residues 48 h following resupply of 2 mM phosphate (Pi) to Pi-starved (–Pi) Arabidopsis thaliana cell cultures. Although other phosphoproteomic studies have documented in vivo N-terminal phosphorylation of AtG6PD6 and its orthologs from other plant species, the functions and mechanisms of this phosphorylation event remain unknown. My research seeks to test the hypothesis that phosphorylation activates AtG6PD6 to enhance OPPP flux during the rapid resumption of cell growth that follows Pi resupply to –Pi Arabidopsis. Immunoblotting with a phosphosite-specific antibody confirmed that AtG6PD6 from Pi-resupplied, but not –Pi, Arabidopsis suspension cells and roots was phosphorylated at Ser18. This correlated with an increase in extractable G6PD activity following Pi-resupply to –Pi Arabidopsis seedlings (i.e., root extracts). Although the native enzyme is highly unstable in vitro, a partial purification of phosphorylated AtG6PD6 was achieved from Pi-replete suspension cells. The purified preparation was rapidly dephosphorylated by incubating with exogenous λ-phosphatase, and the kinetic properties were investigated. Assessing the interplay between Pi nutrition and cytosolic G6PD phosphorylation may contribute to our understanding of post-translational OPPP control in plants, while identifying targets for developing Pi-efficient crop varieties. Such cultivars are urgently needed to alleviate agriculture’s over-reliance on massive applications of non-renewable and polluting Pi fertilizers.
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.
Kate Mitchell, MSc Candidate, Martin Lab The impact of wind turbines on the distribution of wintering and migrating raptors Renewable energy sources, such as wind power, are rapidly expanding as governments aim to fight climate change. However, wind turbines may negatively impact surrounding wildlife. Raptors are birds of prey, essential in maintaining their ecosystems. Raptor collisions with wind turbines are heavily studied, but the spatial displacement of these birds due to wind turbines has received less attention. Understanding collisions and displacement are both necessary to comprehend the overall effects of wind turbines on raptors. In this study, we used standardized surveys to record the presence, number, and location of wintering and migrating raptors on Amherst Island for three years before and after the wind turbines were built to assess whether the wind turbines have affected raptor distributions.
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.
Tazi Rodrigues, MSc Candidate, Blanchfield Lab 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. 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. |
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