Biological Sciences Undergraduate Works

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    Conservation of genetic diversity using life history predictors of adaptive potential
    (2025-04) Goertz, Alyssa; Fraser, Kevin (Biological Sciences); Detwiler, Jillian (Biological Sciences); Garroway, Colin
    Biodiversity loss is reducing population sizes globally, leading to a decline in genetic diversity. This is concerning, as genetic diversity is vital for species' survival and adaptation to future environmental change. Conservation frameworks, such as the International Union for Conservation of Nature (IUCN) Red List, assess extinction risk but overlook genetic diversity and adaptive potential. This is primarily because genetic data is not available for most species. My project directly addresses the lack of consideration of genetic diversity conservation framework by examining the relationship between adaptive potential and easy-to-measure life history traits. If easy-to-measure traits reflect adaptive potential, they can be used to guide conservation where direct estimates of adaptive potential are lacking. Adaptive potential reflects the additive genetic variance (VA) underlying fitness. VA reflects genetic diversity and capacity for adaptation and is used in calculating heritability. I hypothesized that life history traits (e.g., body mass, longevity, fecundity, and age of maturity) predict adaptive potential, measured by heritability. The data for heritability were derived from studies by Mittel et al. (2015), Holstad et al. (2024), and life history trait data from Myhrvold et al. (2016). Data inclusion consisted of heritability measured for morphological, life history, behavioural, and physiological traits, for terrestrial vertebrate species and from wild populations. The relationship between heritability and life history traits was measured using generalized linear mixed models. My results revealed significant relationships between heritability and life history traits. Larger body mass and longer lifespan were associated with low heritability, while larger litter/clutch sizes and earlier ages of maturity were associated with high adaptive potential. Morphological heritability estimates exhibited stronger correlations with life history traits compared to other heritability estimates, suggesting they may be a more reliable proxy for predicting adaptive potential. These findings highlight the potential of using life history traits to infer species’ genetic diversity and adaptive potential, offering a valuable tool to improve conservation prioritization.
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    Canopy-dependent environmental factors impact on nitrogen fixation in Shepherdia canadensis in the boreal forest and tundra
    (2025-03) Tydings, Jason; Renault, Sylvie (Biological Sciences); Fraser, Kevin (Biological Sciences); Markham, John
    Actinorhizal shrubs, plants that symbiotically associate with nitrogen-fixing bacteria and do not depend on soil nitrogen, can increase productivity and facilitate successional changes. High-latitude environments are characterized by harsh abiotic climatic conditions that limit nitrogen availability to plants. However, actinorhizal shrubs are less prevalent at higher latitudes, even though those environments are generally nitrogen-limited. Reduced year-round temperatures, water availability, and light availability are all thought to limit nitrogen fixation due to its energetic costs, making nitrogen fixation unfavourable at higher latitudes. Shepherdia canadensis (buffalo berry) is an actinorhizal shrub that is found in higher-latitude environments across Canada. We wanted to determine, within the northern edge of the boreal forest and tundra, how much nitrogen fixation is occurring in buffalo berry, and how it varies across naturally occurring habitat and canopy-dependent environmental factors. The natural abundance stable isotope technique was used to quantify nitrogen fixation, while canopy-dependent variables were measured using hemispherical image analysis. We found that buffalo berry shrubs were getting a majority of their nitrogen content through nitrogen fixation (55.32% - 94.74%) and that on average, fixation occurred at a higher rate in the forest (74.67%) compared to the tundra (68.00%). Notably, foliar δ13C values varied with canopy openness. Specifically, shrubs in more open areas and the tundra had higher δ13C values, which were interpreted to be a result of stomatal closure in response to reduced water availability. Nitrogen fixation was found to be sensitive to water availability, decreasing with canopy openness (17.99% – 99.79%). This limitation could reduce the productivity of nitrogen-fixing plants in response to warmer climate conditions.
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    The Role of Physical Movement in Spinal Cord Repair Using an Adult Zebrafish Model
    (2025-03) David, Gabrielle; Xing, Lei (Biological Sciences); Stacey, Joy (Biological Sciences); Lindsey, Ben; Jeffries, Ken
    Spinal cord injury (SCI) is a debilitating medical condition that can lead to lifelong paralysis. Failure to regain mobility and restore neurons can be attributed to the non-permissive microenvironment within the mammalian spinal cord that is characterized by prolonged inflammation and glial scarring. Unlike mammals, the zebrafish has a remarkable ability to regenerate neurons in the spinal cord following a complete transection. Aside from the activation of chemical pathways that promote growth, zebrafish also have ependymoglial (stem) cells surrounding the central canal that can proliferate and differentiate into all cell types of the spinal cord. Previous studies have investigated factors that promote neuronal regeneration, yet the contribution of locomotion remains unevaluated. Thus, we aimed to explore the role of physical movement in spinal cord repair by developing a swim column that elicited swimming activity (exercise treatment) from injured fish. This apparatus was developed using an aquarium pump to direct flow into a PVC tube placed within an acrylic tank. Adult male zebrafish from motor neuron reporter line, Tg(hb9:eGFP), were used. Results showed that the exercise treatment slowed the rate of recovery and diminished normal swimming behaviour. Downstream analysis of distance travelled, mean velocity, and mobility state duration revealed that SCI fish treated with exercise had delayed recovery compared to SCI fish that were untreated. Contrary to previous studies using mammalian models, we found that functional mobility was hindered, and swim restoration was limited. Furthermore, our findings contrast other zebrafish exercise studies that demonstrated increased neurogenesis in larvae, and attenuation of age-related diseases such as sarcopenia and cardiac failure. These contradictions may be attributed to sample size, experimental timeline, treatment duration, and stress levels. Although the current study did not yield statistically significant results, these preliminary findings lay the groundwork for deeper exploration of movement in regenerative models
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    Protecting plants against the fungal pathogen Sclerotinia sclerotiorum using host-induced gene silencing
    (2025-04) Caners, Rhey; Whyard, Steve (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Belmonte, Mark
    Sclerotinia sclerotiorum is a fungal pathogen that affects Canadian crops every year. Brassica napus (canola) is particularly vulnerable. Chemical fungicides are widely used to control S. sclerotiorum. However, with increasing concerns about resistance and ecological effects, it is necessary to develop new and improved control methods. Host-induced gene silencing (HIGS) is an RNA interference technology that has the potential to be harnessed to create transgenic, pathogen-resistant crops. In this study, I analyzed the effectiveness of four independently transformed lines of Arabidopsis thaliana expressing RNA to silence the NOB1 gene (SS1G_07873) in S. sclerotiorum. Three of the lines expressed double-stranded (ds)RNA while the fourth line expressed paperclip (pc)RNA, a novel RNA structure which folds over itself on both ends to protect it from nucleases. The analysis was done through detached-leaf lesion assays and transcript knockdown analysis of the NOB1 target gene as well as three known interacting genes. Though improvements are required, the lesion assays show significant decreases in lesion size. Transcript knockdown analysis revealed insignificant changes in NOB1 expression. The interacting genes analyzed showed a significant reduction in transcript abundance, indicating that further experiments are required to understand the processing of foreign RNA in the plant. With further testing to optimize HIGS using SS1G_07873, this technology has the potential to be replicated in crop plants as a means of protection against S. sclerotiorum.
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    Using long-read sequencing to diagnose rare neuromuscular disorders: a pilot study
    (2025-03) Martin, Alexandria Brooke; Wright, Galen (Max Rady College of Medicine); Lee, Jae-Hyeok (Biological Sciences); Hartley, Jessica; Belmonte, Mark
    Many individuals with suspected genetic neuromuscular disorders (NMDs) remain undiagnosed despite extensive conventional genetic testing, which generally employs short-read sequencing (SRS) methods. Long-read sequencing (LRS) is a recently introduced technology which offers improved genome coverage and variant detection missed in standard approaches. Therefore, this pilot study aimed to investigate the application of long-read whole genome sequencing (LR-WGS) with the PacBio Revio platform for five participants (four families) with undiagnosed NMDs to identify causal genetic variants. Retrospective participant chart reviews were first conducted to assess phenotype, inheritance patterns, and other clinical factors. Following this, a novel bioinformatics pipeline was developed to enhance variant annotation and prioritization by integrating LRS population data with established genomic population frequency databases and in-silico predictions of deleteriousness. Finally, manual filtration was performed to further refine variant prioritization based on the clinical insights gained from chart reviews. Candidate variants of interest were found in three of four families analyzed (75%), including strong candidates in the FLNC and DMD genes, and a potential candidate in the TTN gene requiring functional validation. This pilot validates the pipeline for analysis of LRS data and provides evidence that LR-WGS could offer improvements over traditional SRS approaches in diagnosing NMDs, particularly in detecting complex variants. Improving accurate molecular diagnosis ultimately leads to better clinical outcomes for affected patients, including personalized treatment strategies and interventions. Future directions include the study of additional participants with NMDs to allow for a more comprehensive evaluation of diagnostic yield and applicability across diverse genetic backgrounds.