Biological Sciences Undergraduate Works

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Access status: Open Access ,
Validation and application of a metagenomics protocol to the root-associated fungal communities of Northern wild rice (Zizania palustris)
(2025-08) Spring, Abby; Markham, John (Biological Sciences); Bakker, Matthew (Microbiology); Klymiuk, Az
The occurrence of root-associated fungi in wetland plants is not yet well-understood, despite recent indications that some contain diverse mycobiomes, including potential plant mutualists. Although arbuscular mycorrhizal fungi (AMF) can be neutral and even parasitic, emerging evidence suggests that AMF provide benefits to many wetland plants, as in terrestrial soils. Dark septate endophytes (DSEs) occur in wetland plants at similar or greater frequencies than AMF and may also confer benefits to host plants. Zizania palustris (Northern wild rice, manômin) is an emergent annual macrophyte found in shallow lakes and slow-moving rivers in central and eastern North America, where it is harvested from both wild stands and cultivated paddies. Despite the significance of this plant to Indigenous peoples and emerging agricultural interests, its fungal diversity in traditional rice lakes or wild stands is currently unknown. To identify the root-associated fungal communities of Z. palustris collected from wild stands across Manitoba and determine its mycorrhizal status, I undertook ITS and 18S targeted amplicon sequencing of the rhizosphere soil and determined the incidence of fungal structures within roots via microscopy. Since wetland soils contain contaminants that inhibit metabarcoding, I optimized DNA extraction and amplification protocols prior to their application to these samples. The ITS data suggested that the rhizosphere is primarily basidiomycotan and ascomycotan. The 18S data identified three genera of AMF available in the surrounding rhizosphere for association with Z. palustris: Glomus, Acaulospora, and Claroideoglomus. The root incidence data showed consistent fungal colonization by aseptate and dematiaceous hyphae, with somewhat lower incidence of hyaline hyphae and AMF-like structures, despite complete inundation of all plants. While confirmation of Z. palustris as a mycorrhizal plant requires sequencing of the root-endogenous fungi, this thesis presents preliminary data confirming the presence of AMF in the rhizosphere and AMF-resembling structures within the roots.
Access status: Open Access ,
Herbivory resistance to generalist feeder Trichoplusia ni of faba bean (Vicia faba) exposed to salinity stress
(2025-03) Lavallée-Shrupka, Caleb; John Markham (Biological Sciences); Kevin Fraser (Biological Sciences); Renault, Sylvie; Avila-Sakar, German
Plants are often exposed to multiple stress factors simultaneously. Exposure to one stress can exacerbate or mitigate the response to a subsequent stress. While salinity and herbivory can impair growth and physiological function individually, their combined effects remain poorly understood. To investigate this interaction and determine if salt tolerance influences resistance to herbivory, Vicia faba (cv. Broad Windsor) plants were grown under salinity (0, 50, 75, 100 mM NaCl) and exposed to cabbage looper (Trichoplusia ni) herbivory. Gas exchange parameters (photosynthesis, stomatal conductance, transpiration) were not significantly affected by salinity after 11 days of treatment. After 20 days, salinity did not affect plant height, stem biomass or water content of most tissues but significantly reduced root and lateral leaf biomass. Total phenolic compounds and total soluble proteins in the leaves were also unchanged. Elemental analysis revealed that salinity significantly increased Na and Cl concentrations in all three tissue types (leaves, stems, and roots), with the highest accumulation in roots. Salinity significantly increased the concentrations of macronutrients (N, P, K, Ca, and Mg) and micronutrients (Fe, Mn, Cu, Zn, and Mo) in the leaves, suggesting efficient nutrient retention in photosynthetically active tissues. Constitutive resistance to herbivory was not significantly affected by salinity. However, induced resistance was significantly impaired in salt-treated plants. Together, these findings indicate that V. faba exhibits moderate tolerance to salinity, maintaining gas exchange and nutrient homeostasis under salt stress while minimizing growth impairments. The compromised induced resistance highlights the vulnerability of inducible defenses and suggests that salinity may force a tradeoff between preserving physiological function and sustaining inducible defences against herbivory. These results emphasize the importance of considering stress interactions when evaluating plant defence.
Access status: Open Access ,
Acute effects of quinoline and 2-methylquinoline on electrical activity of great pond snail (Lymnaea stagnalis) neurons
(2025-04) Tramley, Cameron; Tomy, Gregg (Chemistry); Markham, John (Biological Sciences); Fry, Mark
Polycyclic aromatic compounds (PAC) are organic compounds found ubiquitously in the environment and originate naturally or anthropogenically. They are persistent, bioaccumulative, and toxic (PBT). PACs have been found to modulate voltage gated ion channels in fish cardiomyocytes. Many studies have examined PACs effects, however, there is growing concern about a less studied class of PACs: hetero-polycyclic aromatic compounds (HPACs). Quinoline and its derivative 2-methylquinoline are two-ringed HPACs found in high concentrations in sediment and tissues of fishes from the Great Lakes. Studies investigating synthetic quinoline derivatives used in the pharmaceutical industry have shown HPACs modulate voltage gated sodium, calcium and potassium ion channels in cardiomyocytes of fishes and mollusk neurons. We therefore designed a study investigating the acute neurobiological effects of quinoline and 2-methylquinoline on Great Pond Snail (Lymnaea stagnalis) neurons, a model with a large easily accessible central nervous system and well conserved ion channels. Electrophysiological characteristics were measured by performing suction electrode experiments on the right internal nerve of the right parietal Lymnaea stagnalis ganglion. Extracellular recordings before and after application of various quinoline or 2-methylquinoline concentrations were used to determine the frequency of right parietal nerve activity which we normalized as percent of control. The extracellular recordings revealed that quinoline affects right parietal nerve activity in a dose dependent manner. Quinoline caused a statistically significant effect on right parietal nerve activity at 1000 nM, but not 100 nM, and 10 nM, with mean percent of control values being 89.2 ± 4.3%, 103.9 ± 4.6% and 99.9 ± 3.5% respectively. 2-Methylquinoline had no statistically significant effect on right parietal nerve activity at 1000 nM. These experiments highlight the importance of understanding the neurobiological effect of PBT environmental contaminants quinoline and 2-methylquinoline, as well as demonstrate the utility of suction electrode recordings as an electrophysiology technique to evaluate acute neurotoxicity of environmental contaminants.
Access status: Open Access ,
Evaluating Nitrogen Utilization Strategies in Chlamydomonas reinhardtii
(2025-04) Tibule, Miku; Doering, Jennifer (Biological Sciences); Markham, John (Biological Sciences); Lee, Jae-Hyeok
Nitrogen (N) is a common, yet essential macronutrient required for nucleic acid and amino acid synthesis for cell growth and biomass of photosynthetic eukaryotes which includes algae and plants. Understanding how organisms strategically use N for growth will allow development of economical use of N fertilizer being invested into croplands, which in return mitigates anthropogenic contribution to environmental pollution. This honours thesis explores N-use strategies by examining the N-sensing mechanisms within Chlamydomonas reinhardtii to investigate its necessity for optimal growth under N-limited and N-repleted conditions through comparative growth within individual N source provision of NH4Cl, KNO3, and urea. Using photobioreactor and nitrogen quantification experiments, I obtained biomass productivity data and residual N within the cultures, which allowed for an understanding of algal growth under various N-source concentration conditions. Through a comprehensive data analysis of growth biomass OD and residual N concentrations, my study uncovered that there is a regulatory mechanism of C. reinhardtii that allows for a reduction in N consumption rate under extreme N limitation stress, which in turn allows the algae to shift its metabolic priorities to internal N-use. These insights contribute to the existing literature by highlighting the significance of the N-sensing mechanism within C. reinhardtii, for N-use strategies, discovering a temporal switch in metabolic function, and offering potential further investigations into how the algae prioritize cellular N contents for growth and cellular division. Ultimately, this study provides a deeper understanding of N assimilation and cellular use, paving the way for future research and developments in the field.
Access status: Open Access ,
Regulation of gene expression by growth differentiation factor 15 in the developing mouse and human neocortex
(2025-04) Mohamad, Ruby; Docker, Margaret (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Xing, Lei
The evolution of the neocortex, specifically its expansion, is the key advancement that made higher cognitive abilities possible. Humans today have a neocortex that constitutes up to two-thirds of their overall brain mass. This expansion reflects increased and prolonged activity of neural progenitor cells (NPCs), which give birth to neurons during fetal cortical development. Growth differentiation factor 15 (GDF15) is a cell-extrinsic signal that has previously been found to promote basal progenitor proliferation, one of the main classes of NPCs critical to human brain development and evolution. Previously, the Xing Lab discovered several potential downstream targets that could be regulated by GDF15 in the fetal human neocortex, including Dachshund Family Transcription Factor 1 (DACH1), Glypican 6 (GPC6), Semaphorin 5A (SEMA5A), and Shroom Family Member 3 (SHROOM3). All of which have been reported to have various roles in neurodevelopment. In this study, we manipulated GDF15 levels in the developing mouse and human neocortex to understand its regulatory effect on the potential downstream targets. My range-finding experiment indicated a concentration-dependent increase in mRNA levels of the downstream targets, with the most increase observed in fetal human neocortical tissue incubated with 100ng/ml recombinant human GDF15 protein. Knockout of the GDF15 gene in embryonic mice revealed decreased mRNA levels of all the downstream targets. Furthermore, adult GDF15 knockout transgenic mice exhibited a decrease in interneuron and deep-layer neuron numbers. My findings are consistent with the notion that GDF15 regulates NPC proliferation through these downstream targets, contributing to long-term effects on neuron abundance in the adult brain.
Access status: Open Access ,
Measuring the Active Learning Gains of Students In Undergraduate Biology Labs Using Peer Review
(2025-03) Bantel, Joseph; Joy Stacey (Biological Sciences); Tamara Kelly (York University); Debets, Cassandra
The peer-review process allows students to engage in the valuable exercise of critically thinking about how they generate and judge the validity of an idea. This is a cornerstone of the scientific community and a core component of biological sciences. Some students in undergraduate studies routinely underperform in the traditional educational experience and benefit greatly from active learning. In a first-year introductory biological science course at the University of Manitoba, I studied the population by using an online peer-review platform called Peerceptiv to study the standardized learning gains of different demographic groups of students to determine if any subgroups experienced a disproportional benefit in this learning exercise compared to any others. I hypothesized that peer-to-peer feedback on scientific graphing would raise the measurable graded assignment scores of URM students in undergraduate biological science, and therefore predicted that there would be no significant difference between URM and non-URM students' graded performance after peer-to-peer input. Students in certain groups did have higher learning gains over the course of the semester when averaged however, these results were not significantly different from the rest of the population. Overall, the reception of the exercise was very positive in student perceptions with 79% of respondents saying that it helped them understand the concepts they learned about. The strongest response was from students saying that getting reviews of their work was the most useful, with 87%. Ultimately, this study shows that students learn from the peer review process and have learning gains associated with it however, additional testing is necessary to definitively say which groups may or may not benefit the most from this activity.
Access status: Open Access ,
Impacts of a flea beetle double-stranded RNA-based insecticide on the ground beetle Pterostichus melanarius
(2025-04) Lampimaki, Silas; Belmonte, Mark (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Whyard, Steve
Flea beetles (Phyllotreta cruciferae and P. striolata) are the most damaging insect pests of canola, one of Canada’s most economically valuable crops. Chemical insecticides are currently the primary method of flea beetle control, but concerns about their impact on non-target organisms highlight the need for safer alternatives. RNA interference (RNAi) has been recognized for its ability to selectively kill insect pests by silencing target genes through sequence-specific exogenous double-stranded RNA (dsRNA). However, sequence similarity between pest and beneficial insects continue to pose risks about potential off-target effects. In this study, two dsRNAs targeting the UBE2L3 and Snf7 gene in P. cruciferae were evaluated for off-target effects in the predatory ground beetle Pterostichus melanarius. A bioinformatic analysis was used to identify the similarity between the dsRNA sequences and their respective orthologs in P. melanarius. Beetles were then injected with the dsRNAs, and relative gene expression and mortality were measured. Following injection of the UBE2L3 dsRNA, which shares 83.4% similarity and a 29 bp matching segment with P. melanarius, target gene expression was reduced by 69.9%. Conversely, injection of the Snf7 dsRNA, which only shares 62.6% similarity, did not induce gene knockdown. Despite the knockdown of UBE2L3, no significant mortality was observed in any treatment group, including the positive control, suggesting that an insufficient dose of dsRNA was used. These findings demonstrate that sequence similarity influences the off-target effects of dsRNA, which can be predicted using a bioinformatic assessment. Continued sequencing of beneficial insects is required so that dsRNA can be designed to have minimal similarity with other species to reduce off-target effects.
Access status: Open Access ,
Investigating the impact of helminths on mercury in Arctic foxes
(2025-04) Whiteside, Kayla; Detwiler, Jillian (Biological Sciences); Davoren, Gail (Biological Sciences); Roth, Jim
Mercury (Hg) pollution in the Arctic poses a growing threat to the health of local wildlife, yet many factors behind Hg bioaccumulation remain poorly understood. Primarily ingested through diet, Hg bioaccumulates in animal tissues and can impair neurological and reproductive functions. Intestinal helminths have demonstrated the ability to take up Hg while residing in their hosts and have consequently been suggested to benefit their hosts through mitigating toxin exposure. In this study, I used Arctic foxes harvested over five years from Churchill, MB to analyze fox muscle total mercury concentrations ([THg]) (ng/g), intestinal helminth [THg], and helminth biomasses to determine if (i) helminth group (taxa and size) influences helminth Hg uptake, and (ii) helminths benefit their host by decreasing host Hg uptake. Results showed that [THg] did not significantly vary with fox sex, age, or harvest year. Cestodes demonstrated higher [THg] than nematodes, though size did not influence [THg] for either taxon. Both cestodes and nematodes demonstrated [THg] increases relative to host [THg], though only the cestodes had significantly higher [THg] than their hosts, and no significant effect was seen for either cestode or nematode biomass on fox [THg]. Overall, this study provides valuable insight into host-helminth-Hg dynamics. Further research is needed to elucidate the mechanisms and significance of helminth Hg uptake to help understand their potential applications in mitigating toxin exposure in wildlife.
Access status: Open Access ,
The effects of topically-applied double-stranded RNA pesticides on Myzus persicae
(2025-03) Joseph, Kelvin Tom; Wilkins, Olivia (Biological Sciences); Lee, Jae-Hyeok (Biological Sciences); Whyard, Steve
The green peach aphid (Myzus persicae) is a major agricultural pest, causing billions in crop losses and contributing to global food insecurity. Increasing incidences of insecticide resistance and off-target effects highlight the need for alternative control methods. RNA interference (RNAi), a gene-silencing mechanism triggered by exogenous double-stranded RNA (dsRNA), has emerged as a promising approach to species-specific pest control. Topically applied dsRNA offers a non-GMO alternative to traditional pesticides, selectively inducing mortality in pests by targeting essential genes. One such gene, Chitin Synthase (CHS), is crucial for the insect exoskeleton, tracheae, and gut. However, dsRNA penetration through the aphid’s hydrophobic exoskeleton remains a challenge, necessitating delivery enhancements like surfactants. This study tested two dsRNA structures—long linear dsRNA (210 bp) and short paperclip RNA (pcRNA, 25 bp)—targeting CHS, with and without the surfactant Silwet. Third-instar aphids were topically treated with a dsRNA droplet, and their survival and fecundity were monitored over eight days. Several bioassay optimizations were implemented, including stretching diet packets, treating third instars instead of adults, filter-sterilizing diets, and chilling aphids before treatment. Bioassays demonstrated that dsRNA + Silwet significantly increased aphid mortality, whereas dsRNA alone and all pcRNA treatments had no significant effects. No significant fecundity reduction or CHS gene knockdown was observed. While only a single gene target was assessed, findings suggest RNAi-based pesticides hold potential for aphid control, and Silwet improves dsRNA efficacy. Further research on optimizing dsRNA formulations could enhance their application as next-generation pesticides.
Access status: Open Access ,
Comparing the boldness and exploration of co-occurring invasive marine crabs (Hemigrapsus sanguineus and Carcinus maenas)
(2024-03) DeJaegher, Emily; Detwiler, Jillian (Biological Sciences); Davoren, Gail (Biological Sciences); Ramey-Balci, Patricia
Boldness (i.e., the propensity to take risks) and exploratory behaviours can influence an animal’s ability to acquire resources, thus affecting competitive success. The Asian shore crab, Hemigrapsus sanguineus, and European green crab, Carcinus maenas, co-occur as highly invasive species in coastal areas of the United States, and more recently, in Atlantic Canada. Both crabs use structurally complex rocky intertidal habitat and consume similar macroalgal and invertebrate prey, such that they likely compete for resources. Competitive interactions between co-invaders could influence the success of either species, affecting their impacts on the ecosystem. Yet, there is a gap in research comparing behaviours, such as boldness or exploration, between co-invaders such as these crabs. Here, the boldness of H. sanguineus and C. maenas are compared by investigating their tendencies to exit preferred rocky habitat with shelter to explore an open and brightly lit area. The crabs’ exploratory tendencies are also compared, by evaluating if the species spontaneously alternate (i.e., preferentially explore regions that they have least recently explored), an indicator of efficient exploration. The two species had similar latencies when exiting the sheltered habitat, but C. maenas spent more time in the open area overall. Both crabs also tended to spontaneously alternate, but H. sanguineus had a greater tendency to do so than C. maenas, revealing for the first time the existence of significant differences in spontaneous alternation behaviour between invasive species. If the strong exploration ability of H. sanguineus can improve the species’ ability to find resources, it may have a competitive advantage over C. maenas in regions where the crabs co-occur.
Access status: Open Access ,
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.
Access status: Open Access ,
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.
Access status: Open Access ,
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
Access status: Open Access ,
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.
Access status: Open Access ,
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.
Access status: Open Access ,
Factors Influencing Testes Size in the Cape Ground Squirrel (Xerus inauris)
(2025) Aston, Gemma; Garroway, Colin (Biological Sciences); Davoren, Gail (Biological Sciences); Waterman, Jane
When males compete through sperm competition, selection favours an increased investment in sperm production to streghten the male’s probability of siring offspring when females multiply mate. This increased investment in sperm quantity results in large testes relative to the species’ size. Thus, testes size can be used as a measure of reproductive fitness in males experiencing intense sperm competition. Despite this relationship, studies investigating testes size have focused on interspecific variation, leaving the factors driving intraspecific variation in testes size an underexplored area of study. I investigated the influence of age, body condition, rainfall, parasite abundance and testosterone concentration on the testes size of Cape ground squirrels, a sciurid known to be under intense sperm competition. Data was collected from males trapped on SA Lombard nature reserve in South Africa between the years 2013-2024 and the influence of each factor on testes mass was assessed using linear regression. Testes mass was found to increase with both age and body condition and body condition also increased with age. While the energetic demands of spermatogenesis appear to shape the relationship between body condition and testes size, declining oxidative stress with age and a terminal investment strategy may drive enhanced testes investment in older individuals. Parasite abundance negatively affected testes size suggesting parasites remove resources from their host that would otherwise be allocated to reproduction. Rainfall and testosterone concentration did not affect testes size. The lack of relationships between rainfall and testes size may have occurred due to the limitations of this study, while testosterone's lack of impact on testes size may be caused by the low testosterone demands of a year-round breeding strategy. These findings aid in our understanding of the factors influencing reproductive success in males experiencing sperm competition and the selective forces shaping intraspecific testes size variation.
Access status: Open Access ,
Effects of Infection with Brainworm Parasite (Parelaphostrongylus tenuis) on the Climbing Behaviour in a Host Gastropod Species (Deroceras laeve)
(2025-04) Dalling, Ness; Van Nest, Byron (Biological Sciences); Markham, John (Biological Sciences); Detwiler, Jillian
Brainworm parasite (Parelaphostrongylus tenuis) is a nematode parasite which typically infects white-tailed deer (WTD – Odocoileus virginianus) as a definitive host, where it often causes no severe harm. It develops through larval stages in terrestrial gastropods and is eventually ingested by the WTD to complete its life cycle. Brainworm can infect other ungulates accidentally, most commonly moose (Alces alces), where it causes serious neurological disease and often death. Here, I investigate the potential role of parasite-modified behaviour in influencing the ingestion of the gastropod hosts by the ungulate host. I hypothesize that when infected with P. tenuis larvae, a gastropod host, the meadow slug (Deroceras laeve) will display altered vertical climbing behaviour, predicting an increase in vertical climbing activity. Vertical climbing behaviour was assessed amongst 15 infected and 45 uninfected slug hosts at four different times throughout the day, on two separate days. I found a significant effect of the interaction between the weight of slugs, their infection status, and the time of day on vertical climbing behaviour. This is novel evidence to support the parasite-modified behaviour hypothesis in P. tenuis and suggests that climbing behaviours may play a role in the transmission of brainworm. Further research would be beneficial, as replicates in this study were low, and the presence of coinfection with a secondary parasite in some samples may have provided a confounding effect.
Access status: Open Access ,
The short-term effects of peer tutoring in first-year biology labs on students with and without ADHD
(2025-03) Chambers, Amanda; Scott, Kevin (Biological Sciences); Waterman, Jane (Biological Sciences); Debets, Cassandra
Peer tutoring is an active learning strategy that has been implemented in many university-level courses. However, many studies that examine the effects of peer tutoring focus solely on the long-term impacts of peer tutoring on learning outcomes and student perceptions, without considering how peer tutoring may affect students with learning differences, such as attention-deficit/hyperactivity disorder (ADHD). Therefore, this study considers the short-term effects of peer tutoring on learning outcomes and perceptions related to understanding metabolic experiments and the ability to focus in students with different relationships with ADHD. Data was collected from students in BIOL 1020 labs at the University of Manitoba during the Fall 2024 semester through an experiment lab, peer tutoring lab, final lab exam, and demographic survey. The main results of this study revealed that peer tutoring had no significant effect on the learning outcomes of students who have different relationships with ADHD. However, peer tutoring did have a significant positive effect on all students’ perceived understanding of metabolic concepts, regardless of their relationship with ADHD. Peer tutoring also had no significant impact on students’ perceived ability to focus, regardless of their relationship with ADHD. The findings of this study not only provide useful information to educators who may want to implement peer tutoring in their labs, but also demonstrate how peer tutoring affects all students the same, and can therefore be considered an inclusive active learning strategy for students, regardless of their relationship with ADHD.
Access status: Open Access ,
Circadian Patterns of Flight in a Long-Distance Migratory Songbird
(2024-07-05) White, Trina; Davoren, Gail (Biological Sciences); Fraser, Kevin
Migration is a common strategy in many different animal taxa, including birds. Most migratory songbirds migrate mainly at night (i.e., nocturnal migrants), with some species migrating primarily during daytime (i.e., diurnal migrants). Some birds can even combine nocturnal and diurnal flights, but these tend to be associated with barrier crossings (e.g., long overwater flights). Whether diurnally migrating songbirds also incorporate night flights into other periods of their spring migrations despite a lack of migration barriers has not been investigated. Further, we lack a precise understanding of the influence of specific environmental conditions on day or night flight behaviour. We investigated circadian patterns of flight in purple martins (Progne subis), a long-distance migratory songbird that journeys between nonbreeding areas in South America and breeding sites in eastern North America. We used direct-tracking (GPS loggers) of individual spring migrations to quantify the daily timing of flights, flight speed, flight distance, and altitude as well as whether these factors were associated with temperature. Birds were tagged with GPS loggers in Winnipeg, Canada, which collected location and altitude every two hours during spring migration. We used Movebank to align location data with average local temperature. We found that martins migrated mainly during daylight, but surprisingly, 15% of flights overland occurred during the night. The average speed for daytime and nighttime flights was similar. We found that neither temperature nor timing of flights influenced flight speed and distance travelled, but flights at higher altitudes were associated with longer flight distance and faster speeds. Our results suggest that a species classified as a diurnal migrant routinely makes night flights overland that are not associated with crossing known migratory barriers. Further studies could increase the sample size of birds and the number of usable GPS fixes, which would allow us to track birds as close to their breeding grounds in temperate areas as possible.
Access status: Open Access ,
Energy Density of Capelin (Mallotus villosus) and Sand lance (Ammodytes americanus and Ammodytes dubius) during the summer in Coastal Newfoundland
(2024-07-05) Vonderbank, Kate; Stacey, Joy (Biological Sciences); Treberg, Jason (Biological Sciences); Davoren, Gail
Spawning capelin (Mallotus villosus) and non-spawning Atlantic sand lance (Ammodytes americanus, A. dubius) adults and juveniles are important forage fish species in coastal Newfoundland during July and August when high abundances of top predators rely on them as critical energy sources. To determine whether these prey types differ in their energy content, and interannual changes in quality, samples of each prey type were collected during July-August 2020 and 2023. Bomb calorimetry was used to measure whole-body dry energy density (kJ/dry g) and calculate wet energy density (kJ/wet g) and water content. Although sand lance are at the peak of their annual lipid cycle and capelin are at their minimum during the summer, adult female sand lance had lower dry energy density (mean of both years ± SE, 20.7 ± 0.11 kJ/dry g) than all capelin sex and maturity categories, and wet energy densities (4.4 ± 0.09 kJ/g) did not differ from capelin. Within capelin, wet and dry energy densities did not differ among gravid females, spent females and males, which contrasts previous findings from before the capelin population in Newfoundland collapsed. Within sand lance, juvenile dry energy density (20.8 ± 0.14 kJ/g) did not differ from adult females. Juvenile sand lance wet energy density was the only prey type that varied interannually, where energy density in 2020 was higher (5.3 ± 0.15 kJ/g), but this is thought to be because the samples were more dried out before collection. Overall, our findings indicate that although sand lance adults and juveniles are similar in wet energy densities to capelin, their lower wet mass per fish would result in a higher number of sand lance needed to reach a fixed energy content per meal. Other factors, including abundance and distribution of each species, also impact foraging costs and must be paired with energy densities to estimate prey type quality.

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