Dr. Eve Marder
University Professor Victor and Gwendolyn Beinfield Professor of Biology Perturbations Reveal that Degenerate Circuits Hide Cryptic Individual Variability More than 40 years of work on the crustacean stomatogastric nervous system on the cardiac sac, gastric mill, and pyloric rhythms have described numerous instances of circuit reconfiguration by neuromodulation and sensory inputs. These reconfigurations can involve alterations in the frequency and phases relationships of rhythms, and switching of neurons from participating in one circuit to another. Computational works shows clearly that there are multiple, degenerate sets of parameters that can result in similar output patterns. Motivated by this, we have studied the effects of several different perturbations on STG networks, revealing animal-to animal differences in their responses that are not evident without extreme perturbation. Short Biography of Eve: Eve Marder is the Victor and Gwendolyn Beinfield University Professor at Brandeis University. She obtained a B.A degree from Brandeis University in 1969, a Ph.D. from the University of California, San Diego in 1974, and did postdoctoral research at the University of Oregon and the Ecole Normale Superieure in Paris, France before assuming her faculty position in 1978. Marder was President of the Society for Neuroscience (2008), and on the NINDS Council, National Academy of Sciences Council, numerous Study Sections, and Advisory Boards for institutions in the USA and abroad. Marder is a member of the National Academy of Sciences, the National Academy of Medicine, the American Academy of Arts and Sciences, and Fellow of the Biophysical Society, the American Physiological Society, and the American Association for the Advancement of Science. She received the Miriam Salpeter Memorial Award for Women in Neuroscience, the W.F. Gerard Prize from the Society for Neuroscience, the George A. Miller Award from the Cognitive Neuroscience Society, the Karl Spencer Lashley Prize from the American Philosophical Society, Honorary Doctorates from Bowdoin College and Tel Aviv University, the Gruber Award in Neuroscience, the Education Award from the Society for Neuroscience, the Kavli Award in Neuroscience. and the National Academy of Sciences Award in Neuroscience. Marder served on the NIH working group for the Obama BRAIN Initiative, and is now on the BRAIN advisory Council. Marder has served on many journal editorial boards. She was Editor-in Chief of Journal of Neurophysiology, and was a Senior and then Deputy Editor at eLife for its first 6 years. Marder studies the dynamics of small neuronal networks, and her work was instrumental in demonstrating that neuronal circuits are not “hard-wired” but can be reconfigured by neuromodulatory neurons and substances to produce a variety of outputs. She combines experimental work with insights from modeling and theoretical studies. With Larry Abbott, her lab developed the programmable dynamic clamp. Her lab pioneered studies of homeostatic regulation of intrinsic membrane properties, and stimulated work on the mechanisms by which brains remain stable while allowing for change during development and learning. Marder now studies how similar network performance can arise from different sets of underlying network parameters, with its relevance for differential resilience in the population. In addition to her original research papers, Marder has published numerous extremely influential review articles which are heavily cited. Additionally, she has published more than 20 short essays relevant to the life of scientists, senior and junior. She has long been an advocate for women, diversity and international representation. Her life was highlighted in a recent book by Charlotte Nassim, MIT Press, 2018 Lessons from the Lobster, Eve Marder’s Work in Neuroscience. Emilie Norris-Roozmon
MSc Candidate, Colautti Lab Associations among self-reported tick-borne disease symptoms, treatments & diagnoses In eastern Canada, deer ticks (Ixodes scapularis) carry a variety of bacterial (Borrelia burgdorferi, Anaplasma, Ehrlichia, Rickettsia) and protozoan pathogens (Babesia) that are responsible for more disease in humans than any other arthropod vector. While most known tick-borne diseases (TBD) in Canada are treatable, invasions of new pathogens may go undetected for decades or more. Misdiagnosed and untreated infections can cause debilitating symptoms, many of which are non-specific and can be mistaken for other diseases. Using quantitative models, the goal of my thesis was to investigate whether tick-borne diseases cause syndromes (e.g., groups of symptoms which consistently occur together). I used supervised machine learning models of self-reported symptoms while accounting for demographic characteristics, clinical tests, and chronic health conditions. An anonymous cross-sectional survey was disseminated online via the Qualtrics software package to survey age, gender, blood test results, symptom profiles, and chronic health conditions. Recruitment was focused on the Kingston-Ottawa corridor because it is a Lyme disease hotspot in Canada, but inclusion criteria included anyone with a self-reported tick bite. This resulted in 1248 unique submissions, 301 of which self-reported a tick-borne disease diagnosis. On average, participants who reported a Lyme disease diagnosis along with one or more secondary co-infections presented with more symptoms and a longer time to diagnosis than participants with Lyme disease alone. A Regularised Discriminant Analysis of 13 binary symptoms correctly classified participants with 98% accuracy into self-reported diagnoses grouped into four categories: Lyme disease, Lyme with one or more co-infections, other tick-borne disease, and no diagnosed disease. To model how healthcare practitioners might diagnose disease, I used hierarchical logistic regressions to identify self-reported factors that predict diagnosis. Skin rash and blood tests were predictive of all three diagnosis categories, accounting for 41-61% of the variation in TBD diagnosis predictions. Participants with chronic health conditions (cardiovascular, rheumatological, and central nervous system disorders) were less likely to receive tick-borne disease diagnoses, which is consistent with misdiagnosed disease. My research shows how symptom profiles can help to understand tick-borne diseases, representing a collaborative approach between scientists and patients that can help to improve diagnosis and knowledge translation in the domain of tick-borne disease. Liying Xu
MSc student, PEARL Lab Understanding spatial patterns of past aridity on the Canadian prairies over the Holocene: Insights based on diatom assemblages from Success Lake The Canadian prairies receive limited precipitation and hence are prone to drought-related environmental, economic, and social impacts. Previous studies have suggested the Canadian prairies are highly subject to extreme drought in the future that resembles the mid-Holocene,which is when many lakes have dried out. Understanding the Holocene aridity profile is critical for us to be able to confidently forecast future drought and aridity, which is essential to establish appropriate policies and programs to reduce negative impacts. I used diatom outer scales buried in Success Lake sediment to reconstruct changes in lake water salinity, which could indicate the change in the aridity over the Holocene on the Canadian prairies. Diatom record from Success Lake revealed four stages of aridity change in its vicinity over the Holocene. Century-scale analysis of the diatom record during the Holocene is consistent with a drier climate in the early-mid Holocene (between 7000 to 5300 yr BP). An abrupt decrease in diatom-inferred salinity between 5300 cal yr BP to 3300 yr BP indicates the onset of a wetter climate, with continuing arid conditions throughout the mid-Holocene. Analysis of the past ~3000 years suggests that the late Holocene was more complex, with extended periods of increased variability in precipitation, characterized by frequent oscillation between the rise and falls in effective moisture. Comparing the aridity record from Success Lake with other paleoclimatic records from the Canadian prairie revealed a west-east moisture variability gradient, showing coherency within western and eastern sites and with opposite trends among the two groups. The mechanism controlling the moisture gradient is likely associated with the positioning and shaping of the jet stream, influenced by ocean-atmospheric interaction and solar radiation. Natural shifts in moisture availability may accelerate global warming, further reducing the precipitation and intensifying the likelihood of extreme drought over the Canadian prairie. Dr. Gregor Fussmann
The Fussmann Lab, McGill University How plankton interacts with the environment – and what happens if it doesn’t As a freshwater and evolutionary ecologist, I study the population dynamics and the evolutionary adaptation of plankton communities. With accelerating climate change, there is a need to understand the ecological and evolutionary responses of complex plankton communities in lakes and oceans. I will present the results of mesocosm experiments that have investigated the effects of rising CO2 and temperature. These factors play a particular role in lake ecosystems because CO2 is taken up by phytoplankton for photosynthesis and changing temperature affects the liquid water phase but also the duration of ice cover. Plankton communities in the wild always interact with their environment, but it is also necessary to gain an understanding of the baseline dynamics that occur when there is “no environment.” In this vein, I will present an alternative experimental approach, which attempts to shut out external environmental factors. In microcosm experiments we explored whether plankton predator-prey cycles can be sustained over long periods of time, as suggested by classical ecological models. Jordan Balson,MSc Candidate
Lefebvre Lab & Environment Physiology and Freshwater Ecosystem Lab Assessing the potential of Caenorhabditis elegans in the bioremediation of M. aeruginosa Reported incidences of cyanobacterial harmful algal blooms, or CHABs, are increasing across the world due to climate change and nutrient loading. CHABs can produce dangerous cyanotoxins and dominate freshwater ecosystems. Microcystis is one of the most common types of cyanobacteria and can produce microcystins. The ecological and human impact of algal blooms are immense, costing $7.8 billion in loss of ecosystem and market asset values in Lake Erie alone. A proactive, targeted approach is needed to bioremediate CHABS. Bioremediation of CHABs with Viviparus georgianus (the banded mystery snail) is somewhat effective, as the snail filter feeds and ingests intact cyanobacteria cells, which are then translocated to the benthos in pseudofeces. Although this keeps cyanobacteria from entering its disruptive colonial phase, this is temporary, as currents eventually liberate the live cyanobacteria cells. Nematodes, such as Caenorhabditis elegans and its relatives, are potential candidates for bioremediating these cyanobacteria-containing pseudofeces in combination with the banded mystery snail. C. elegans have been shown to have detoxification pathways, which may break down microcystins. As well, cyanobacteria have been found in C. elegans’ microbiome, making it likely that they ingest cyanobacteria in nature. We aim to examine the potential of C. elegans for multi-stage bioremediation of Microcystis. We aim to evaluate the potential of C. elegans to ingest, digest and detoxify Microcystis and pseudofeces; as well, we aim to determine what impacts this diet has on C. elegans’ health. We hypothesize that nematodes are viable organisms for bioremediating CHABs in combination with V. georgianus and that nematodes will be able to ingest, digest and detoxify Microcystis cells contained within snail pseudofeces. Sarah Beech, MSc Candidate
Environment Physiology and Freshwater Ecosystem Lab Spatial ecology of two Lake Whitefish spawning aggregations in Lake Ontario and the Bay of Quinte Lake Whitefish (Coregonus clupeaformis) in the Laurentian Great Lakes have experienced overexploitation by commercial fisheries and major ecological changes throughout the past century. In Lake Ontario, the Lake Whitefish population was severely reduced and has shown minimal reproductive success since the 1990’s. In Canadian waters, two major spawning aggregations persisted in the eastern basin and currently support a commercial fishery. The declined state as well as the socio-economic and ecological importance of this species has emphasized the need for current research and knowledge. Using acoustic telemetry, this project analyzed the spatial distribution and movement patterns of two spawning groups of Lake Whitefish in Lake Ontario and the Bay of Quinte. Spatial analysis revealed clear differences in space use between the spawning groups. The spatial discreetness observed between the spawning groups suggests differences may exist in commercial exploitation and factors related to bioenergetics such as diet and energy expenditure. Understanding the current behaviour and ecology of Lake Whitefish will also be important for management of the commercial fishery and future conservation efforts. Dr. Rebecca Batstone Institute for Genomic Biology, University of Illinois at Urbana-Champaign The complex genetics of symbiotic extended phenotypes in a model mutualism A goal of modern biology is to develop the genotype-to-phenotype (G-P) map, a predictive understanding of how genomic information generates the organismal trait variation present in natural and managed communities. As microbiome research advances, however, it has become clear that many of these traits are governed by genetic variation encoded not only by the host’s own genome, but also by the genomes of myriad cryptic symbionts. Thus many ecologically-important traits, such as plant yield and pathogen resistance in agriculture, are actually symbiotic extended phenotypes, and this recognition adds even more complexity to our conceptions of the G-P map. Here, I present recent work (see bioRxiv links below) examining naturally-occurring genetic variation in 191 strains of the model N-fixing symbiont, Ensifer meliloti, in four association mapping studies. Using this data, I identify three key features of the G-P map that must be accounted for if we want to predict the evolution of symbiotic extended phenotypes: i) genotype-by-environment (G x E) interactions, ii) genotype-by-genotype (G x G) interactions; and iii) symbiotic pleiotropy, whereby loci influence traits not only of their bearer, but also of interacting individuals. I hope to convince you that the identity and function of loci underlying symbiotic extended phenotypes are largely environmentally-dependent, yet we can nonetheless identify universal loci that are likely important in all or most environments, and thus, serve as excellent targets both for genetic engineering and future coevolutionary studies of symbiosis.
bioRxiv links: https://www.biorxiv.org/content/10.1101/2021.08.03.454976v2.full https://www.biorxiv.org/content/10.1101/2021.07.19.452989v2.full Phinyaphat Srithiphaphirom, PhD Candidate Department of Biology, Robertson Lab, Queens' University Rapid cold hardening and stress-induced spreading depolarization in the central nervous system of Locusta migratoria Rapid cold hardening (RCH) is a short-term hormesis in which brief chilling (minutes to hours) significantly enhances the stress tolerance of an animal. Insects live in varied habitats and thus experience different kinds of environmental stresses. To thrive, insects enter a reversible coma, or hypo-energetic state when they are under stress. This is associated with a sudden loss of ion homeostasis and temporary shutdown in the central nervous system (CNS), which is a hallmark of spreading depolarization (SD). Insectstress tolerance is dependent on the sensitivity of their nervous systems to unfavourable conditions, which can be modulated by RCH. Using pharmacological and electrophysiological approaches, we investigated the mechanism of RCH and its effect on stress-induced SD in locusts, Locusta migratoria. We showed that RCH delays the onset of both chill- and anoxia-induced SD. Octopamine (OA) is an insect stress hormone, and we showed that OA mimics, whereas its antagonist, epinastine (EP), blocks, the effect of RCH on chill- and anoxia-induced SD. Thus, we concluded that OA mediates the RCH-induced delay of the onset of anoxia-induced locust coma. Lastly, we investigated whether RCH affects anoxia-induced SD via one or more of the following homeostatic mechanisms that are involved in maintaining K+ gradients: Na+ /K+ -ATPase (NKA), Na+ /K+ /2Cl- co-transporter (NKCC), and voltage-gated K+ (Kv) channels. We showed that NKA and Kv channels (excluding the Shaker family) modulate SD occurrence and possibly take part in the mechanism of RCH, whereas NKCC is directly involved in the mechanism of RCH. Altogether, we suggested that RCH regulates NKA, NKCC, and Kv channels through an octopaminergic pathway to modulate stress induced SD in locusts.
Michelle Kong, MSc. Candidate Department of Biology, Wang Lab, Queen's University Measuring the efficiency of bioremediation of cyanobacterial harmful algal blooms With rising global temperatures, harmful algal blooms have been increasing in size and frequency for several decades. These blooms produce and release toxins while severely reducing the oxygen levels of marine and freshwater ecosystems, resulting in large scale mortality events of aquatic life. Cyanobacterial harmful algal blooms (CHABs) produce cyanotoxins, which have caused poisoning cases of aquatic life, agricultural animals, and humans alike. A key element in a proactive approach to controlling CHABs may be bioremediation, which is the use of naturally occurring organisms to consume environmental pollutants. Viviparus georgianus, the banded mystery snail, is ubiquitous to freshwaters, naturally occurs in high densities, and can safely ingest cyanobacteria with high tolerance and rapid detoxification effects, making them an ideal candidate for use in bioremediation. However, little is known about their consumption, their rate of consumption, and how it may be affected by the species of cyanobacteria present and density of snails. We placed V. georgianus in microcosms with varying species of cultured algae or cyanobacteria, as well as varying densities of snails and then measured the quantity of cyanobacteria ingested via chl-a levels. Through this, we were able to observe V. georgianus’ consumption of cyanobacteria at a similar efficiency to green algae, as well as significant drops in chl-a with as little as 3g of snails per 200mL of water. By understanding how to optimize V. georgianus’ consumption of cyanobacteria, we can make use of a widespread and highly populous species for efficient and effective inhibition of bloom growth.
Samreen Munim, MSc Candidate
Department of Biology, Martin Lab, Queen's University Do acoustic signals diverge or converge where geographic ranges overlap? Closely related bird species often have similar acoustic mating signals because of their shared recent ancestry, which can affect their reproductive isolation and ability to live together when they overlap in range. Mating signals are mostly used to attract mates and interact with competitors of the same species, but closely related species can also respond to these signals, which can lead to costs of co-occurrence, both direct (e.g., hybridization, aggression) and indirect (e.g., as a by-product of ecological divergence). As a result, where closely related species overlap in range, we expect mating signals to diverge to minimize these costs. However, the opposite can also occur: signals may converge in sympatry (i.e., range overlap) because of similar selective pressures from the environment, or from introgression or cultural drift. Moreover, selection to reduce aggressive encounters can also lead to convergence. Whether signals more often diverge or converge when species overlap in range is poorly understood, particularly for acoustic signals. To address this gap, I used a comparative framework wherein each comparison involves a pair of closely related sister lineages that differ in whether they overlap in range with a third, more distant lineage within the same genus. For each comparison, I found recordings of birds and compared the signals of the sympatric pair of species to the allopatric (i.e., no range overlap) pair to see if acoustic signals more often diverge or converge when closely related species overlap in range. The results of this study will help us better understand signal evolution and the maintenance of species barriers in sympatry, with consequences for the broad patterns of biodiversity we see in nature. |
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