Honours Theses/Papers

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Mitigating disturbance to breeding seabirds during drone censuses in the Arctic
(2024) Adams, Reid
Drones provide an opportunity to rapidly census avian species in remote areas, addressing challenges associated with traditional methods and potentially reducing disturbance to the birds. Despite the increasing use of drones for avian monitoring, there is no consensus on the best practices for effective monitoring with minimal disturbance. In partnership with local communities, surveys and analyses were conducted on the responses of multiple culturally and ecologically important Arctic seabird species (Common Eiders, Double-crested Cormorants, Great Black-backed Gull, Herring Gull, Ring-billed Gull) to drone censuses. The investigation focused on drone flight parameters associated with heightened flushing events. I found no flushing during drone takeoff, suggesting effective methods for future researchers to minimise seabird disturbance during drone takeoff. The majority of flushing events occurred during drone approaches to nesting colonies and overhead flights. I observed high variation in response to the drone from the gull species and observed a greater response than expected from Common Eiders. Drone approach speed was a significant predictor of seabird flushing, with flushing events minimised during drone approach at speeds below 4m/s and altitudes above 50m. Regarding overhead flights along the surveying transect, drone survey speed was a significant predictor. Overhead behavioural responses were effectively mitigated with drone speeds below 5 m/s and altitudes above 50m. I provide optimal drone practices to minimise disturbance to breeding seabirds during census in remote Arctic regions, covering takeoff, approach, and overhead flight. Additionally, I discuss practical environmental concerns researchers should consider when employing these methods.
Investigating PAI-1, ICAM-1, and VCAM-1 expression dependence on neural activity within the acute phase of stroke in mice endothelial cells
(2024) Burford, Samuel A.
Stroke is a leading cause of death and disability worldwide. Following an Ischemic stroke, of which 87% of all strokes are, a spreading depolarization occurs, propagating damage to healthy tissue. Through initial experimentation, the procoagulant protein Plasminogen Activator Inhibitor-1 (PAI-1) displayed a unique expression pattern 24 hours following an ischemic stroke model in mice, producing a localized region of expression within endothelial cells contralateral to the stroke site. Through the application of a strong GABA agonist and using a passive diffusion method to limit tissue damage, my goal was to determine if the neural activity of the spreading depolarization was responsible for PAI-1 expression. I also aimed to observe expression patterns of Intracellular Adhesion Molecule-1 (ICAM-1) and Vascular Cell Adhesion Molecule-1 (VCAM-1) using immunolabelling. Expression of PAI-1 through immunolabelling was inconclusive due to high levels of endogenous binding of the secondary antibody. An attempt to limit endogenous binding was unsuccessful. VCAM-1 imaging did not display significant expression, however ICAM-1 did display a stroke dependent expression, in a pattern where proximity to the stroke site was indicative of total expression. Though PAI-1 expression manipulation was inconclusive, the potential for neural dependency in its expression remains. ICAM-1 expression results indicate a correlation between ICAM-1 expression and inflammation following stroke and likely does not display any neural activity dependence. If neural activity dependence can be further investigated in PAI-1, along with the identification of a potential neurovascular coupling pathway, then the expression of other vascular proteins may be studied to better understand the implications and reach of spreading depolarizations, along with the potential damage or resilience they may provide.
The intergenerational effects of glucose enrichment on the reproduction of C. elegans
(2024) Bass, Elizabeth
Despite glucose being shown to have detrimental effects on reproduction, the intergenerational impacts of diet on reproduction have not been well investigated. The ‘Fetal Origins of Disease’ hypothesis suggests that a parent's environment affects the health of the offspring in their adult life. Therefore, I hypothesized that offspring that remain on the same media as their parents will be better suited to that environment and, therefore, better able to reproduce later in life. I used Caenorhabditis elegans to test this hypothesis. The parental generation of C. elegans lived on nematode growth medium (NGM) or NGM supplemented with 20 mM glucose for two days. Fertilized oocytes were taken from these individuals and served as the offspring generation. The offspring were raised on NGM before being placed on one of the experimental mediums. Four experimental groups were created: an NGM to NGM group, an NGM to glucose group, a glucose to glucose group and a glucose to NGM group. A late mating assay was completed to determine each group's reproductive ability and oocyte quality analysis using DIC of mated hermaphrodites on Day 5 of adulthood. Significant differences suggested that exposure to glucose only in the parental generation or only in the offspring generation negatively impacted the late-reproductive capacity of the offspring. The late-reproductive capacity of worms exposed to glucose for two generations was significantly better than that of those exposed to glucose only in the offspring generation. This suggests that prior parental exposure to glucose may be beneficial for living in a high-glucose environment. Assessment of oocyte quality based on the presence of cavities between oocytes, regularity of shape and reduction in oocyte size also produced significant differences between groups. Exposure to glucose only in the offspring generation significantly decreased the size of the oocytes and increased the presence of cavities compared to those not exposed to glucose. Exposure to glucose only in the parent generation significantly reduced the size of the oocytes. No significant differences were found in the regularity of shape between each group. These results suggest that exposure to glucose decreases reproductive capacity later in life, partially due to decreased oocyte quality. The effects of glucose exposure in the parent generation may result in epigenetic changes that can be harmful if the offspring returns to an NGM diet but may be beneficial if the offspring remains on the diet.
Characterizing the acute damage response of CX3CR1:GFP+ cells in the cornea using live whole-mount imaging
(2020) Gulka, Sebastian
Immune cells serve a plethora of roles within the body. This includes responding to tissue damage efficiently to limit injury-related complications and restore homeostasis. In the cornea, this function is critical, as improper healing can lead to a loss of vision due to corneal scarification/neovascularization or by damage to the retina that is initiated by the inflammatory response to corneal healing. It is currently unknown what cells are first responders to tissue damage within the cornea, and what this response looks like. Previous research has indicated that the cornea contains macrophages in the stroma and dendritic cells in the epithelium. To determine how this response manifests CX3CR1:GFP mice—which have one copy of the chemokine receptor CX3CR1 replaced with GFP—were used. Mice were euthanized, eyes enucleated, and the anterior chambers of each eye were injected with the lipophilic dye FM4-64 to label cell membranes. The whole eye was used for live-imaging and damage procedures. Corneal damage was induced by using a high-powered laser focussed on the basal layer of the corneal epithelium. Surrounding CX3CR1+ cells were observed for 2.5 hours after the injury. Proximal stromal CX3CR1+ cells responded to damage by extension of filipodia towards the damaged region over the course of about 30 minutes, however, no cell migration was noted. Epithelial dendritic cells did not respond as vividly as macrophages. Immunolabeling revealed that responding macrophages were MHCII+, while MHCII- cells did not respond to damage. This study is a preliminary look at damage-responding cells in the cornea and has successfully identified a subset of responding cells. Questions that remain to be answered are: what is the secretory profile of responding cells, what is the end-goal of the response, and how can corneal immune cells be decisively classified based on functionality.
Interhemispheric migration of resident macrophages and microglia in the stroke brain
(2020) Templeman, Julia
Confocal microscopy and immunohistochemistry were used to observe the interhemispheric migration of immune cells in the brains of mice after an induced stroke. When a sham stroke was induced in the brains of Cx3Cr1-GFP female mice there was no immune cell migration from the injected to the stroke hemisphere, but when an ischemic stroke was induced, there was significant migration towards the stroke area. Further immunohistochemistry determined that the majority of these migrating cells were resident brain macrophages, and none of them were microglia. This study also revealed a non macrophage, non microglial cell type that carried 34.91% of the microspheres towards the stroke. They are presumed to be immune cells that do not express the fractalkine receptor CX3CR1 such as neutrophils, dendritic cells, myeloid cells, or monocytes. More research with more cellular labels is needed in order to fully elucidate the phenotype of these cells. These results show that a stroke does provoke the interhemispheric migration of resident brain macrophages in the female mouse brain.
Ammonium, nitrate, and proton flux in fern gametophytes
(2024) Creasy, Em
Total net NH4+, NO3-, and H+ fluxes were investigated in three species of fern gametophytes: Polystichum munitum, Christella dentata, and Cyrtonium falcatum. Flux measurements were performed with a microelectrode ion flux measurement (MIFE) system. Overall, net NH4+ influx was seen in all gametophytes. Net NO3- efflux and net H+ influx was seen in most gametophytes. The gametophyte generation of C. dentata and C. falcatum displayed greater NO3- efflux than the sporophyte generation. On average, male P. munitum gametophytes displayed greater per-unit-area NH4+ uptake than female/hermaphrodite gametophytes, though the latter showed greater NH4+ uptake at the whole-organism level. This finding suggests that fern gametophytes may conform to the expectations of nutrient-based sex determination. This study was the first to perform precise ion flux measurements at discrete positions on fern gametophytes and sporophytes. This research provides greater insight into the nutrient ecology of fern gametophytes, an under-studied field.
Evaluating putative Dryas ajanensis ssp. beringensis x Dryas integrifolia hybrids - A leaf morphometric analysis
(2024) Friele, Kai
Dryas is an alpine and circumpolar genus of long-lived dwarf shrubs in the Rosaceae family. Extensive hybridization within this genus makes species identification challenging. This is especially the case in alpine areas of British Columbia, where Dryas integrifolia and Dryas ajanensis may be mis-identified due to the presence or absence of leaf scales. These misidentified individuals have been considered putative D. ajanensis  D. integrifolia hybrids. The main goals of this study were to 1) evaluate leaf morphology in D. ajanensis, D. integrifolia, and their putative hybrids, 2) determine the leaf characters of fundamental importance in distinguishing the putative hybrids from their parents, and 3) provide insight on the range of the putative hybrids. A morphometric analysis of Dryas leaves from herbarium specimens was conducted to test the hypothesis that D. ajanensis  D. integrifolia hybrids have intermediate leaf morphology to that of D. ajanensis and D. integrifolia. Fifteen leaf traits including size, shape, and the presence of glands and scales were assessed on three leaves each of 101 specimens. Lobe depth, extent of lobe cover, length, width, and the presence or absence of scales and glands were identified as important traits in differentiating the parent taxa and putative hybrids. The putative hybrids did not show discrete intermediacy to the parent species but rather showed continuous morphological variation between the parental extremes. This pattern of variation is consistent with the morphological variation observed in hybrid swarms, rather than F1 hybrids. Overall, the results suggest that putative D. ajanensis  D. integrifolia hybrids in western North America originated from a hybrid swarm similar to Dryas hybrid swarms observed elsewhere. Within British Columbia, there is an unusual situation in that the hybrid occurs far south of one parent (D. ajanensis), but not as far south as the other parent (D. integrifolia).
Prenatal delta-9-tetrahydrocannabinol exposure leads to persistent deficits in hippocampal synaptic plasticity
(2024) Green, Victoria
Following legalization, cannabis rates have been increasing, and despite low self-reporting, it is known that cannabis is now one of the most commonly used drugs during pregnancy. In crossing both the placental and blood-brain barrier, delta-9-tetrahydrocannabinol (THC), the most well-understood component of cannabis, has access to the developing fetal nervous system and to the neuromodulatory endocannabinoid signaling system, where it acts as a cannabinoid receptor 1 and cannabinoid receptor 2 partial agonist. To investigate possible long-term consequences of prenatal THC exposure in rats, a subtype of synaptic plasticity, long-term potentiation (LTP), was investigated in vitro in the dentate gyrus of adult male and female offspring following prenatal exposure between gestational days 5 to 20. LTP was found to be significantly decreased in both sexes of animals exposed to THC, with evidence from additional paired pulse and input-output tests suggesting that the THC-induced changes are specific to the mechanism underlying LTP and not to the basal excitability of the circuits. These findings contribute to the existing body of knowledge on the dangers of drug use during pregnancy.
Mortality of the intertidal copepod, Tigriopus californicus, in response to sequential temperature and salinity stressors over different latency periods
(2024) Hackett, Brooke
Organisms are subject to constant fluctuations in their physical environment, both short and long-term. While many organisms are adapted to cope with slight fluctuations in their environment, anthropogenic influences are causing these stressors to become more frequent and extreme, prompting researchers to study how multiple stressors impact animals. Currently, few studies have researched sequential stressors. In nature, intertidal organisms can experience drastic changes in their physical environment multiple times throughout a single day as the tides change, as waves splash, and as weather changes indicating that simultaneous stressor studies may not be reflective of natural conditions and are thus uninformative. To address this gap, I investigated the mortality patterns of a common intertidal copepod, Tigriopus californicus, in response to different sequences of 12-hour freshening (66% reduction in salinity) and 12- hour temperature (either a -15 °C or +16 °C change) stressors with three latency periods of 0, 12, and 24 hours. My experiments revealed complex interactions between stressors, with the survival outcomes influenced by the order and timing of stress exposure. I observed that the fresh-fresh sequence exhibited high survival rates in heat experiments but lower survival rates in cold experiments, suggesting differential responses to stressors based on seasonal conditions. Furthermore, the influence of prior pool conditions, including salinity and temperature, on copepod survival was evident, with variations in mortality across different tide pool locations. The effect of latency between stressors on copepod survival varied, with longer latency periods generally associated with slightly higher survival rates. Our findings highlight the importance of considering sequential stressor exposures and the temporal dynamics of environmental conditions in understanding the resilience of marine organisms to changing climates. This study contributes to our understanding of the adaptive strategies employed by T. californicus in response to environmental stressors and underscores the need for further research on the mechanisms underlying stress tolerance in marine populations.
Exploring fungal strategies: a comparative analysis of peroxidase enzyme secretion in ectomycorrhizal and arbuscular mycorrhizal fungi
(2024) Innes, Freya
Understanding the role of mycorrhizal associations in soil organic matter (SOM) dynamics is important for managing ecosystem functions and mitigating climate change impacts on forests. In this study, I compared soils under 100% Pseudotsuga menziesii D. (Douglas-fir), characterized by ectomycorrhizal (EM) associations, under 100% Thuja plicata T. (western red cedar) with arbuscular mycorrhizal (AM) associations, and under a 50:50% balanced mix of both tree species. I used peroxidases, a lignin modifying group of enzymes secreted by mycorrhizae to access nutrients in organic structures, to test between nutrient acquisition strategies of EM and AM. I found 2.75 times as much total forest floor peroxidase concentration in the Douglas-fir plots with EM associations compared to the western red cedar plots with AM associations. This indicates the importance of mycorrhizal symbionts in nutrient acquisition. My results suggest that the ability of EM to produce peroxidases that degrade complex molecules within SOM is a distinct nutrient acquisition strategy employed by this group of mycorrhizae. I also observed lower total peroxidases in mineral soil compared to forest floor, potentially due to the 30-year age of the stand and the early stage of development of the fungal community in mineral soil layers. Covariate analysis revealed that exchangeable potassium, sodium, manganese (Mn), and the carbon-to-nitrogen ratio (C:N) were all positively correlated with total forest floor peroxidase concentration. Exchangeable Mn and the C:N ratio were likely the most influential factors due to the impact of C:N on fungal community compositions. My findings underscore the importance of mycorrhizal symbionts in shaping soil carbon dynamics and highlight the potential for targeted management strategies to optimize soil organic carbon storage and reduce loss of carbon through respiration.
Shell variability in Littorina obtusata along the Eastern Canadian intertidal in response to crab predation and novel niches
(2024) Kinahan, Will
Predation is a pervasive biological process that shapes species-species interactions and morphological adaptations within populations and across ecosystems. Observing the dynamics of predator-prey interactions within the intertidal remains difficult, although not impossible. In this study, I observed how crab-induced shell injuries of the Flat Periwinkle (Littorina obtusata) vary among abiotic and biotic conditions along the intertidal communities of Newfoundland and Nova Scotia. Extending from the observations of 21,613 shells retrieved from 92 localities upon various macrophytes (Ascophyllum nodosum, Fucus vesiculosus, F. serratus, F. edentatus), my results indicated the following. 1) L. obtusata in Nova Scotia exhibited a twofold increase in injury prevalence compared to those found in Newfoundland. 2) Between localities, categories algae cover, and intertidal slope were not significant in explaining the differences observed in shell injury, however wave exposure did effect the outcome of shell injury depending on province. 3) Substrates varied in degrees of shell injury accumulation. 4) Shell injury prevalence was significantly dependant on macrophyte type in 14 localities, although, shell injuries overall were more prevalent if collected from the F.serratus. 5) The presence of shell injuries dependant on shell colour varied dependant on macrophyte type, with some localities exhibiting increased frequencies of injury dependant on shell colour and their fucoid background. Through these preliminary findings, I argue that select abiotic and biotic factors influence the outcomes of predator-prey interactions and highlight the complex nature of trait directionality.
Stress, reelin, and the entorhinal cortex: Exploring the effect of chronic stress on reelin density in the rat entorhinal cortex and the correlations with cognition, emotion, and inflammation
(2024) Kurz, Katerina E.
Chronic stress is a risk factor for depression, Alzheimer’s disease, and other disorders. Reelin is a protein with roles in cortex development, synaptic plasticity, and immune responses. Reelin is dysregulated in the hippocampus, hypothalamus, and other regions in these disorders and others. The entorhinal cortex (EC) plays an important role in episodic and spatial memory: with ties to the hippocampus, reelin expression, and shows alterations in depression. To examine the effect of chronic stress on the reelin positive (reelin+) cells in the EC and the connections to cognitive, emotional, and immune systems, 36 rats underwent a 14 week cyclic chronic stress model of depression. A subset of rats received an injection of reelin on the last day to test whether reelin treatment reverses depression-like behaviour and restores reelin in the EC. Behavioural tests were conducted, and immunohistochemistry was used to stain reelin+ cells. Reelin treatment reversed depression-like behaviour, but no effect of chronic stress on EC reelin+ cell density was observed, suggesting that chronic stress does not affect the levels of reelin+ cells in the EC as it does in other regions such as the dentate gyrus. Correlations were examined between reelin+ cell density, forced swim test immobility, spatial memory, and spleen white pulp (WP) area. There was no relationship between reelin+ cell density and immobility time, however there was a significant correlation between spatial memory and reelin cell density in males. This correlation was disrupted with chronic stress but successfully recovered with a reelin injection, suggesting a sex-specific relationship between spatial memory and reelin levels in the EC. Males showed significant white pulp atrophy and recovery with reelin, but only females showed a significant correlation with reelin+ cell density. This suggests a role of reelin in modulating inflammatory responses, and highlights another sex-specific difference. The disruption by chronic stress in the correlation between cognitive tests and EC reelin+ cells, and the subsequent recovery by a single reelin iv injection should be further explored when considering the putative fast-acting antidepressant actions of reelin, and that cognitive symptoms in depression patients aren’t properly solved by current antidepressant treatment.
Examining the role of calcium signalling in endothelial cells and microvascular obstruction in the mouse brain
(2024) Oshanyk, Adam
Recently, research has revealed that obstructions in the microvascular network of the brain contribute to the pathology of various detrimental neurological disorders. Dysfunctional vascular mechanisms could account for the higher prevalence of these obstructions. However, an understanding of the specific mechanisms contributing to microvascular obstruction remains limited. Therefore, this study aimed to elucidate how cerebral calcium signalling in endothelial cells contributes to microvascular obstructions, as calcium signalling is implicated in vascular mechanisms governing vasodilation and regulating vascular tone, factors potentially contributing to microvascular obstruction. Using transgenic mice, we selectively attenuated endothelial calcium signalling through conditional Cre-expression and assessed obstruction risk by intravenously injecting fluorescent microspheres. Our results reveal that attenuating cerebral endothelial calcium signalling has no significant effect on the density of stalled microspheres compared to controls. These findings suggest cerebral endothelial calcium signalling may operate redundantly or play a minor role in cerebral vascular obstructions. Our results underscore the complexity of vascular mechanisms in the brain and emphasise the need for future research in this area.
Preliminary study of history, distribution, use, and reproductive biology of seaside juniper (Juniperus maritima)
(2024) Strachan, Kailey
Seaside juniper (Juniperus maritima) is a recently discovered tree species. To date, little research has been done on it. My study aimed to gather preliminary information on the sex ratios within the populations and the filled seed per cone (FSPC) from multiple locations around Vancouver Island and the Gulf Islands. Locations in central Vancouver Island had the largest, healthiest populations, and the highest mean FSPC. The locations in southern Vancouver Island had both the smaller and unhealthier populations: they had catastrophic FSPC numbers. The sex ratio of this species is 40% males, 60% females, which is opposite to traditional dioecious gymnosperm sex ratios. I also investigated the Indigenous history of seaside juniper and its involvement in spiritual and protective practices. My results draw attention to a declining species and encourage increased efforts in conservation and land management.
Modelling the effect of type 2 diabetes-like hyperglycemia on ferritin expression and investigating the effects of iron chelation on lifespan in Caenorhabditis elegans
(2024) Urdahl, Jasmin Violet
The relationship between iron homeostasis and glucose metabolism has recently gained attention, as researchers attempt to uncover therapeutic approaches to treat type two diabetes. Type II diabetes mellitus (T2DM) is one of the most common endocrine disorders in the world. The prominence of hyperglycemic diets in Western countries has drastically increased the prevalence of T2DM. Both glucose and iron can act as biological stressors on cells, and result in increased production of reactive oxygen species (ROS). This can ultimately lead to pancreatic cell damage and impaired insulin signalling, as characterized by T2DM. Human ferritin, or the ortholog FTN- 1 in C. elegans, is an iron storage protein that plays a crucial role in mitigating oxidative stress caused by excess iron. In an attempt to elucidate physiological responses in iron metabolism to T2DM-like conditions, a unique C. elegans mutant worm was used, ftn-1p
Assaying the role of complement factor D on retinal pigment epithelial cell pathology in a mouse model of Stargardt disease
(2024) Xie, Xiaoya
Stargardt disease (STGD) is a macular dystrophy caused by mutations in ABCA4. ABCA4 loss-of-function leads to the accumulation of bisretinoids, known as lipofuscin, in the retinal pigment epithelial (RPE) cells in the retina. When photoxidized, lipofuscin can become toxic and cause RPE cell damage as well as activating the complement system of innate immunity. Complement factor D (CFD) is necessary for activating a branch of the complement system called the alternative pathway (AP) and is hypothesized to compromise normal RPE homeostasis which in turns promotes RPE lipofuscin accumulation and photoreceptor degeneration in Stargardt disease. This study examined the process of lipofuscin accumulation over time and how the loss of CFD affects STGD development in 6-month and 12-month Abca4-/- mice by quantifying (i) 488 nm RPE autofluorescence as a measure of the accumulation of lipofuscin in paraffin-embedded eye sections, and (ii) the immunofluorescence level of C3 (a critical protein in complement system activation) in the RPE. My results showed that the 488 nm autofluorescence level increased between 6-month and 12-month Abca4-/- mice, and between the 12-month Abca4-/- and the age-matched wildtype mice. However, the autofluorescence levels were unchanged among the 6-month experimental genotypes. The C3 immunofluorescence level in most of the 6-month experimental genotypes was unchanged. Due to the absence of the disease phenotype (i.e., elevated 488 nm autofluorescence) in the 6-month experimental samples, the role of CFD in STGD progression could not be assessed. Since the results of the autofluorescence assay on paraffin-embedded sections in this study are consistent with what has been observed by others in the Chow lab on flat-mounted RPE, cross-section tissue slides may be used as an alternative for examining the progression of STGD.
A mouse model of Rett syndrome shows a cell-autonomous reduction of α4* nicotinic receptors in dopaminergic neurons of the substantia nigra pars compacta
(2018) Le Gratiet, Keyrian
Rett syndrome (RTT) is a neurodevelopmental disorder due to spontaneous mutations in a gene (MECP2) on the X chromosome. With the mutations typically found in the paternal germline, female RTT patient are more common than males and manifest a constellation of severely debilitating symptoms after birth. Development is mostly normal during the first 6 months but then stalls and regresses resulting in individuals that lack motor coordination, have impaired speech, and exhibit Parkinsonian symptoms often accompanied by seizures. Mice with the same mutation have many neuronal dysfunctions including poor neural communication, some of which is due to improper signaling by the transmitter acetylcholine (ACh). The cholinergic system is critically involved in the generation of purposeful behaviours including voluntary motor acts, which correlate with some of the conditions seen in RTT patients. The present study investigated whether mutant (Mecp2-) dopaminergic (DAergic) cells have downregulated α4-containing (α4*) nicotinic acetylcholine receptor (nAChRs) expression compared to wild-type (Wt) (Mecp2+) DAergic cells in the substantia nigra pars compacta (SNc) of a RTT female mouse and whether this downregulation was cell-autonomous. Spectral confocal imaging was used to quantify the YFP-tagged α4* nAChRs in five-week-old Mecp2EGFP/+/ α4YFP/+, Mecp2+/- / α4YFP/+, and Mecp2+/+ / α4YFP/+ female mice. Imaging confirms that mutant DAergic neurons have reduced expression of α4* nAChRs compared to spatially colocalized Wt DAergic neurons in the SNc of a young RTT female mouse. Furthermore, the reduction in nAChR expression in DAergic neurons was found to be cellautonomous with Wt DAergic neurons from the RTT female and DAergic neurons from Wt females displaying similar amounts of α4* nAChRs on their soma. Finally, there was convincing evidence for spatially-modulated reduction in nAChR expression in mutant DAergic neurons with the lateral SNc showing a greater reduction in levels of nAChR expression compared to the medial SNc. To our knowledge, this is the first study to provide anatomical evidence for a cellautonomous downregulation of α4* nAChR expression in DAergic neurons in the SNc of a young RTT female mouse.
Congenital anomalies in Nunavut: Trends and current status
(2018) Morello, Michelle
BACKGROUND: Congenital anomalies (CAs), also known as birth defects, constitute a substantial proportion of infant and child morbidity and mortality, placing an excessive burden on health care systems. In Canada, Nunavut has twice the number of overall CAs compared to Canada (99.7/1,000 Vs 51.5/1,000), contributing to the highest rates of certain CAs in the country. Specifically, congenital heart defects (CHDs) are seen to be exceedingly high in this population. PURPOSE: To assess the current status and trends of birth prevalence of CAs in Nunavut over a 25-year time span. METHODS: CAs ascertained from a chart review of 2249 live births of children born from January 1, 2010 and December 31, 2013 (four years) to mothers residing in Nunavut was carried out and compared to previous chart reviews of 2567 Inuit births from 1989 and1994 and 2019 Inuit births from 2000 to 2005. CAs were coded according to the ICD-10 system. Evaluation of the use of administrative data to report CAs was also accomplished by comparing results to data previously reported by the Canadian Congenital Anomaly Surveillance System (CCASS) from 2006-2012. RESULTS: The rate of CAs for the current chart review was 64.03/1,000 live births or 6.4%. A total of 144 CAs in 118 infants with one or more anomaly were reported. The overall rate was lower by one-third (31.9%) compared to the chart review completed from 1989-1994 (61.36 vs 93.10 /1,000; OR: 0.64, 95% CI 0.51-0.80, p<0.0001). The greatest difference was seen in CAs of the musculoskeletal (MSK) system (0.45/1,000 vs 8.95/1,000LBs; OR: 0.28, 95% CI 0.13-0.58, p=0.0002). No significant differences in the overall rate of CAs were found when compared to the 2000-2005 chart review. CAs of the MSK system again accounted for the greatest difference when compared to the second chart review (4.45/1,000 vs 10.40/1,000 LBs; OR: 0.42, 95% CI 0.18-0.95, p=0.0290). In comparison to the CCASS, the rate of total anomalies was one-third (34.3%) lower (64.0/1,000 vs 82.2/1,000; OR 0.76, 95% CI 0.62-0.93, p=0.0064). CHDs affected 3% of births in this chart review. There were no differences in the rate of CHDs in comparison to the previous chart reviews; however, rates were elevated in comparison to the CCASS (OR 1.44, 95% CI 1.04-1.97, p=0.0212). CONCLUSIONS: CHDs continue to be elevated in this population and are a large contributor of CAs in Nunavut. Future study to understand the genetics of CHDs in relation to the Inuit is suggested. Monitoring smoking, alcohol, folate and vitamin A levels for women in child-bearing years should continue as they play a large role in the prevention and prevalence of CAs. The use of administrative data provided by the CCASS to report CAs in Nunavut is limited and a more comprehensive system is needed.
Stoichiometric C:N:P ratios of saprophytic and ectomycorrhizal fungi across edaphic gradients on Vancouver Island
(2018) Harmon-Denhoed, Rachael
Soil microorganisms are key players in nutrient cycling in many ecosystems. Ecological stoichiometry is the study of elements and how they are conserved throughout ecosystem cycles. Ecological stoichiometry can be complemented by the metabolic theory of ecology which is concerned with the thermodynamic resource allocation processes that govern the movement of elements within the biomass of plants, organisms and their substrates. These theories were applied in this study to interpret patterns of nutrient stoichiometry in soil, plants and fungi. The objectives of this study were to determine if fungi exhibit homeostatic C:N:P ratios across an edaphic gradient and if significant variation exists in C:N:P ratios between fungal guilds. Saprotrophs and ectomycorrhizal fungi were the two guilds used in this study to represent two fungal nutrient acquisition strategies: free-living organic matter decomposers and root symbionts. The C:N:P ratios of the ectomycorrhizal and saprotrophic fungi were 218:17:1 and 101:11:1, respectively. The results showed that there were varying degrees of homeostasis present in ectomycorrhizal and saprotrophic fungi. This study demonstrated that the differences in guild were significant and that the differences in nutrient acquisition strategies of the two fungi was reflected in their C:N:P stoichiometry. Saprophytes appear to be more homeostatic than ectomycorrhizal fungi. Ectomycorrhizal fungi mirror relationships found within the soil and conifer needles which may relate to their intimate relationship with both the substrate and host plants. Future research should include a fungal community analysis to determine whether stoichiometric plasticity is due to community composition shifts, as well as more specific substrate analysis to determine how microsites and rates of decomposition affect the stoichiometry of fungal organisms.
A comparison of Saprolegnia parasitica gene expression in the presence and absence of a host
(2018) May, Emily
As the importance of aquaculture increases globally, determining the infection strategies of opportunistic fish pathogens like Saprolegnia parasitica grows increasingly vital. Saprolegnia parasitica, a hemibiotrophic oomycete, has an initial biotrophic stage in which it suppresses host defences to facilitate infection, but the molecular mechanisms behind this infection strategy are largely unknown. In this study, I tested the hypothesis that expression of two S. parasitica virulence genes differs in the presence and absence of a host. The studied genes were: SpHtp1, a putative RXLR-like effector gene and SPRG_13235, a potentially horizontally transferred disintegrin gene with no known oomycete analogs. To test my hypothesis, I exposed pure S. parasitica zoospore cultures either to water imbued with Salmo salar effluents or to sterile water; then, I extracted RNA from experimental samples and measured expression differences with polymerase chain reactions (PCR). I successfully used nested PCR with gene-specific primers to qualitatively analyze expression, but quantitative analyses with real-time PCR (qPCR) were unsuccessful. Based on qualitative analyses, I concluded that SPRG_13235 was expressed in low amounts in both host presence and host absence, implying that factors other than host presence mediate gene expression variance. I was unable to determine whether SpHtp1 expression varied. Future studies should consider both studied genes but should focus on SPRG_13235, which remains largely uncharacterized. Disintegrin proteins inhibit vital cell functions by blocking integrin ligand-binding domains, potentially making them vital for host infection. The SPRG_13235 primer sets designed in this study can be used to facilitate future research in this area and can also be used to effectively detect S. parasitica propagules in environmental samples.

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