Hana Thompson MSc Candidate, Eckert lab A shift from sexual to asexual reproduction in a wetland plant: implications for range edge dynamics All species have limits to their geographic distributions, and these limits are thought to reflect a failure of adaptation to conditions beyond the range. The adaptive capacity of populations at range limits could be strongly influenced by the amount and distribution of genetic variation, which in turn is strongly affected by variability in reproductive system, particularly in plants which exhibit diverse reproductive modes. Plants can reproduce sexually, either through outcrossing (exchanging pollen with other individuals) or self-fertilization. Many plants have the capacity for some form of asexual reproduction as well, by producing parthenogenic seeds or clonal reproduction via vegetative propagation. Sexual and asexual reproduction have different ecological requirements, meaning that a species with both methods of reproduction can have separate sexual and asexual niches. In some species, the sexual niche is narrower than the asexual niche, thus shifts to asexuality might allow these species to thrive in environments where sexual reproduction is inhibited. Decodon verticillatus is a wetland plant that reproduces sexually through most of its range and exhibits a shift to asexual clonal reproduction at the northern range margin. For my master’s research I am investigating the evolutionary causes and consequences of this shift to asexuality, and the implications for range edge dynamics in Decodon verticillatus using a transcriptomic analysis of RNA-seq data. I found that the range-edge populations show genetic signatures of long-term asexuality, such as increased heterozygosity and a breakdown of isolation by distance. This suggests that the asexual populations are long-lived and well-established, and that shifting to asexuality may have allowed range expansion beyond the sexual niche of D. verticillatus. Understanding the factors that influence range limits and range expansion is becoming increasingly important to better anticipate the capacity of species to adapt, and potentially shift their ranges in response to anthropogenic environmental changes.
Lee Marie Raytek MSc Candidate, Snedden Lab & Plaxton Lab In vivo hyperphosphorylation of the Ca2+/calmodulin-dependent glutamate decarboxylase isozyme AtGAD1 in phosphate-resupplied Arabidopsis thaliana Inorganic phosphate (Pi) has a crucial role in plant development, yet it is often the most limiting macronutrient of many soils. Pi starved (-Pi) plants elicit a Pi starvation response that alters gene expression and metabolism to enhance their efficiency of Pi acquisition and use. This research field is enabling the development of innovative strategies for engineering Pi-efficient crops, urgently needed to reduce inputs of unsustainable and non-renewable Pi fertilizers for long-term global food security and ecosystem preservation. Our recent phosphoproteomic study revealed that the glutamate decarboxylase AtGAD1 became in vivo phosphorylated at multiple serine residues (located near its N-terminus) 48 h following resupply of 2 mM Pi to -Pi cell cultures of the model plant Arabidopsis thaliana. AtGAD1 is a root-specific, cytosolic GAD isozyme. GADs catalyze the first committed step of the 4-aminobutyrate (GABA) shunt by decarboxylating glutamate into GABA, an important yet enigmatic ‘stress’ metabolite and apparent signal molecule. GAD is the only enzyme of central plant metabolism known to be activated by Ca2+/calmodulin-binding; however the functions or mechanisms of plant GAD phosphorylation have not been studied, although similar N-terminal hyperphosphorylation of AtGAD1 and its orthologs has been described in numerous studies of the phosphoproteome of Arabidopsis and other plants. My thesis research seeks to test two hypotheses: (i) phosphorylation inhibits AtGAD1 activity, and/or (ii) phosphorylation affects AtGAD1’s subcellular localization. This involves comparing the physical and kinetic properties of FPLC-purified, native phospho- versus dephospho-AtGAD1, and molecular cloning of mCherry-AtGAD1 fusion constructs needed to visualize the enzyme’s location in –Pi versus Pi-resupplied cells. Assessing the interplay between Pi nutrition and AtGAD1 phosphorylation will contribute to elucidating the physiological roles of GABA and the GABA shunt under Pi stress and potentially other stresses.
Dr. Eric Capo Institut de Ciencies del Mar, Spanish National Research Council Merging two worlds: application of molecular ecology tools in paleolimnology to study the long-term changes in aquatic microbial communities Historical deposits of sedimentary DNA are a promising target for molecular tools with potential to inform about long-term changes in aquatic microbiome (i.e., bacteria, archaea protists, fungi, viruses) and how microorganisms are controlled by viral infection, pathogens, and larger predators (e.g., zooplankton and fish). As sedimentary DNA archives can encompass timescales that span decades to hundreds of thousands of years, they complement and enhance contemporary data derived from water monitoring. The data from such historical monitoring is integrative and enable ad hoc assessment of biological responses to past environmental and more recent anthropogenic perturbations. Over the last decade, studies using sedimentary DNA metabarcoding successfully reconstruct temporal changes in microbial communities, including cyanobacteria and microbial eukaryotes. I present here an overview of this research field, some of my ongoing research projects on lakes Biwa (Japan), Ekoln (Sweden) and the Black Sea, and reveal the potential to answer questions that can only be provided when including sedimentary DNA for the reconstruction of long-term temporal changes in aquatic microbial communities.
Bio: Eric Capo has a PhD in molecular paleoecology with skills in molecular biology, data analysis and aquatic microbial ecology. His interests lie in the ecology of aquatic systems (freshwater and marine systems), the temporal dynamics of microbial communities and their functional responses to environmental perturbations (climate, eutrophication, mercury pollution). He is the founder and coordinator of the sedaDNA scientific society, an international network of sedaDNA research and the co-founder of Mersorcium, a consortium about microbial Hg-cycling in the environment. Patrick Wolf MSc Candidate, Tufts lab Acoustic Telemetry Provides New Insights on the Ecology of Smallmouth Bass in Eastern Lake Ontario Smallmouth Bass (Micropterus dolomieu) are an integral freshwater predator with a wide
distribution in North America. Our understanding of Smallmouth Bass ecology is extensive but primarily based on research from smaller inland lakes, rivers, and reservoirs. Smallmouth Bass are native to the Great Lakes, but much less is known about their ecology in these large waterbodies. In Lake Ontario, there is an urgent need for additional research on this species due to suggested changes in their population status by provincial and state agencies. Smallmouth Bass in the Southern Great Lakes have also recently experienced large increases in angling pressure due to the region's growing popularity of bass tournaments. The main objective of the present study was to examine whether a novel acoustic telemetry approach could be used to obtain new information on the ecology of Smallmouth Bass in the eastern basin of Lake Ontario. This study showed that it was possible to continuously monitor an experimental group of Smallmouth Bass using acoustic telemetry from September 2020 to October 2021. These results provide new evidence that Smallmouth Bass exhibit local residency in large lake ecosystems to a much greater degree than previously understood. Observations from acoustic transmitters also showed changes in the seasonal ecology of resident fish. Wintering areas were not far from summer home ranges, but Smallmouth Bass occupied deeper depths and reduced their activity during the winter. Some of these results have important implications for assessing and managing Smallmouth Bass populations in the Great Lakes. Marco Lee, PhD Student Nelson and Moyes Lab Metabolic Phenotype of Daphnia under Hypoxia: Macroevolution, Microevolution, and Phenotypic Plasticity Hypoxia is a stressor that influences animal function from ecology to molecular biology. Animals cope with hypoxia through strategies that improve oxygen delivery and anaerobic energy metabolism. Daphnia is a freshwater crustacean that can upregulate hemoglobin (Hb) in response to hypoxia, imparting a red color. We combine multiple field surveys across season with a common garden experiment to evaluate changes in the metabolic phenotype of Daphnia in relation to environmental hypoxia. We observed seasonal changes in the metabolic phenotype that differed between red and pale animals. Hb was upregulated early in the season in Daphnia in hypoxic lakes, and a relationship between Hb and lactate dehydrogenase, a key enzyme in anaerobic metabolism, only emerged later in the season in a lake-specific temporal pattern. To evaluate whether these differences were due to specific lake environments or microevolutionary differences, we ran a common garden experiment using six isofemale lines from each of four lakes. We found a strong response to 18 h hypoxia exposure in the expression of both Hb and lactate dehydrogenase. Unexpectedly, other glycolytic enzymes, pyruvate kinase and enolase, were not upregulated under hypoxia. This contrasts observations in vertebrate models, as hypoxia often triggers a suite of responses controlled by the master transcriptional regulator hypoxia-inducible factor. Overall, the combination of lab and field studies suggest that the metabolic phenotype of the animal is dictated by both microevolutionary differences (within and between lakes) as well as the spatial and temporal environmental heterogeneity of the lakes. In addition, hypoxic responses in Daphnia may be regulated by serveral independent pathways, highlighting the importance of studying animal models with distinct ecology to understand the evolution of hypoxia-driven phenotypic remodeling.
Dr. Nancy Turner University of Victoria “More Than Just a Tree”: Recognizing Intangible Cultural Values of Nature "In this talk, I discuss the complex ways of knowing that inform Indigenous Peoples’ traditional land and resource management systems through the lens of ethnoecology. In particular, I focus on the values embedded with traditional ecological knowledge systems, and how these influence peoples’ relationships with other species and approaches to environmental stewardship, especially relating to trees and other plants. I also introduce the notion of “kincentricity” in which the inextricable interconnections among humans, other species and our environments are explicitly recognized. I provide examples of these perspectives, with first-hand accounts by Indigenous knowledge holders from western Canada, as well as stories and ethnographic evidence. With today’s drastic declines in global biodiversity and rapid climate change, the knowledge and perspectives relating to the environment of peoples who have lived sustainably in their home places “since time immemorial” are particularly relevant. " ——Nancy
Glafira Ermakova MSc Candidate Chin-Sang Lab Investigating the effect of tumour suppressor PTEN/DAF-18 variants and mammalian insulin on the insulin and insulin-like signaling pathway in Caenorhabditis elegans The insulin and insulin-like growth factor signaling (IIS) pathway is highly conserved across all metazoans and is responsible for a variety of developmental processes in which disruptions can lead to dysregulated cell growth. The IIS pathway gets activated in the presence of high levels of nutrients and its primary role is to cause a growth-stimulating response throughout the organism. Due to the pathway’s anabolic nature, it’s overactivation may cause excessive cell proliferation, tumour formation, and even behavioural impairments such as autism spectrum disorder (ASD). As any other key pathway, proteins play an important role up and downregulating the overall effects of the IIS pathway. In humans, tumour suppressor protein Phosphatase and Tensin Homolog, also known as PTEN inhibits IIS, preventing excessive growth and development. The IIS pathway is highly conserved between mammals and the model organism Caenorhabditis elegans (C. elegans). However, while insulin acts as an activator of the IIS pathway in mammals, in C. elegans mammalian insulin has been shown to act as an antagonist, further complicating the role of insulin in C. elegans. The first aim of my thesis research was to work with C. elegans to characterize variants of the human tumour suppressor PTEN in worms by looking at effect of 5 mutations in the homologous C. elegans protein DAF-18. By determining the effects of these mutations on the model organism C. elegans, we can potentially infer how these variants play a role in human disease formation, such as the development of ASD. The second aim of my research was to explore the effect of mammalian insulin on the development of C. elegans. A potential treatment for diseases involving hyperactivation of the IIS pathway might involve an engineered antagonistic human insulin which could bind to the insulin receptor and downregulate it through competitive inhibition. However, if C. elegans is to be used as a model to study human insulin and its activation properties on the IIS pathway, we first need to elucidate the effect of the human insulin on the C. elegans insulin receptor DAF-2. If human insulin can have an agonistic effect on our model organism, then we might be able to use it as an assay to assess the function of human insulin in vivo.
Mia Rondinelli, MSc Candidate DiCenzo Lab Variations in carbapenem resistance associated with the Verona Integron‑encoded Metallo‑β‑lactamase across the order EnterobacteraleS The dissemination of genes encoding antimicrobial resistance (AMR) in populations of pathogenic bacteria is an inconvenient truth of microbiological research. Infections with resistant bacteria are twice as likely to result in serious health conditions and three times more likely to result in death when compared to their non-resistant counterparts, accounting for approximately 700 000 global deaths yearly. The use of antibiotics at sub-therapeutic levels in livestock to boost the cost-efficiency of feed, the increased prevalence of multidrug resistant pathogens in nosocomial environments, and the continued over-prescription and misuse of medically relevant antibiotics are just a few of the factors contributing to the increased prevalence of AMR, meaning that it is crucial that we continue to study how AMR genes operate within their hosts and spread across populations of pathogenic bacteria. In my thesis project, I am investigating the factors that contribute to carbapenem resistance in six multidrug resistant clinical isolates from Kingston General Hospital across the order Enterobacterales. Although these six isolates contain the same carbapenemase gene, vim-1, their minimum inhibitory concentrations of ertapenem (a clinically relevant carbapenem antibiotic) vary more than tenfold across strains. Therefore, my research seeks to address the factors contributing to ertapenem resistance phenotype by identifying the microbial physiology supporting this resistance and broadly investigating the molecular epidemiology of vim-1 in the Kingston region.
Dr. Tamzin Blewett University of Alberta Understanding the complex toxicity of chemical mixtures in freshwater environments Hydraulic fracturing is a technique used globally to recover oil and gas from impermeable sources (e.g. shale, coal beds). During this process chemical additives are injected into the ground at high pressures to “fracture” rock formations yielding oil and gas. Over time mixtures of the injected chemicals and hydrocarbon products will flow back to the surface as a complex solution termed flowback and produced water (FPW). Spills or applications (e.g. as a dust and ice suppressant) of hydraulic FPW can be devastating to freshwater environments. During this presentation I will review the current knowledge of FPW toxicity to freshwater organisms with larger implications on ecosystems. The key toxic components of the FPW mixtures will be highlighted, as well as potential mechanisms by which effects on individuals are exerted. Consideration will be given to real-world exposure scenarios, and the possible biological and ecological impacts if the thawing Arctic hydrocarbon reserves are subjected to this method of oil and gas extraction.
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