Graduate Theses & Dissertations

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Mitogenome characterization of the shortnose sturgeon (Acipenser brevirostrum) for international trade validation of aquaculture-reared caviar
Identifying the population origin of aquaculture-reared caviar is crucial for both conservation and management strategies of farmed fish but could also facilitate international trade of a CITES regulated product. Shortnose sturgeon (Acipenser brevirostrum) is the main source of caviar production in Atlantic Canada, from Breviro Caviar Inc. aquaculture facility. Shortnose sturgeon are also listed as a species-at-risk under the Species At Risk Act. Currently there is no genetic method for delineating wild from aquaculture-reared caviar. By targeting the mitochondrial genome (mitogenome) using novel long-range PCR primers and next-generation sequencing (NGS) methods we have successfully sequenced the full mitogenome of 37 shortnose sturgeon. The purpose of this study was to increase the resolution of diagnostic variation among populations and to validate Canadian aquaculture-reared stock from wild US populations. Results provided a previously unobserved novel control region haplotype in high frequency within both the aquaculture-reared and Saint John River wild sample sets. Similar frequencies were observed with whole mitogenome haplotypes. Diagnostic mitochondrial lineage found in high frequency within the captive Breviro Caviar Inc. population has the potential to allow caviar product from Breviro Caviar Inc. to be distinguished from protected US shortnose sturgeon populations. The application of full mitogenomic characterization provides the potential to further resolve differences between aquaculture and natural Canadian shortnose sturgeon stocks, US/Canadian populations and to contribute to future conservation strategies. Future research identifying signatures of selection on the mitogenome between captive and wild populations and across latitudinal gradients found within the species range. These novel methods have produced a proof-of-concept to provide a "farm-to-fork" validation and ecobrand of Breviro Caviar Inc. product and its aquaculture origin to support importation into US caviar markets. Author Keywords: aquaculture, mitogenome, next-generation sequencing, species-at-risk, sturgeon
Sexual Dimporphism and Population Dynamics of Sub-Arctic Breding Dunlin (Calidris alpina hudsonia) near Churchill, Manitoba, Canada
Around the world, many populations of migratory shorebirds appear to be declining. Conservation strategies to reverse declining trends rely on, among other information, a firm understanding of breeding ground population dynamics. From 2010 to 2014, I studied a breeding population of Dunlin (Calidris alpina hudsonia) near Churchill, Manitoba using mark-recapture methods. I found that females were significantly larger than males. I subsequently developed an equation based on morphological features that successfully classified 87.1% of females and 92.6% of males, sexed using molecular techniques. Using program MARK, I quantified the annual apparent survival of adults (± SE) within the breeding population (0.82 ± 0.063 for males, 0.73 ± 0.12 for females). Transient adults made up a significant percentage of the female population (32%, P = 0.011), but non-significant in the male population (12%, P > 0.05). Re-sight rate was high for both sexes, and ranged from 0.86-0.90 per year. Sex, year, and nest initiation date were the factors that had the greatest influence on annual returns. There was no significant difference in mean inter-annual nest site distance between sexes (male: 82.01 ± 13.42 m, female: 208.38 ± 55.88 m, P > 0.05). The high survival estimates obtained in this study suggest that the breeding population is stable and may not be contributing to suspected population declines within the subspecies. Author Keywords: demography, discriminant function analysis, mark-recapture, sexual size dimorphism, survival
Characterization of frog virus 3 and its binding partner LITAF
Iridoviruses are large (120-200nm) double stranded DNA viruses that contain an icosahedral capsid. The iridoviridae family is composed of five genera that infect a wide range of poikilothermic vertebrates (Lymphocystivirus, Ranavirus and Megalocyivirus) and invertebrate hosts (Iridovirus, Chloriridovirus). Frog virus 3 (FV3) is a member of the Ranavirus genus, and is commonly used as a model system to study iridoviruses. I was interested in understanding virus-host interaction in FV3. I studied two viral genes, FV3 97R and FV3 75L. Here I demonstrate that 97R localizes to the endoplasmic reticulum (ER) at 24 hours post-transfection. However, at 35 hours post-transfection 97R localizes to the ER but also begins to form concentrated pockets, continuous with the nuclear membrane This study found that 97R possess a unique phenotype and that its localization to the ER is mediated through its C-terminus transmembrane domain. FV3 75L encodes an 84 amino acids protein. I showed that FV3 75L localizes to the early endosomes, while its cellular binding partner, LITAF, localizes to late endosome/lysosome. Interestingly, when FV3 75L and LITAF are co-transfected into cells, LITAF can alter the subcellular localization of FV3 75L to late endosome/lysosomes. A physical interaction between LITAF and FV3 75L was demonstrated through a pull-down assay and that a highly conserved domain found in both proteins may mediate the interaction. LITAF has been proposed to function in protein degradation, but there is still uncertainty on LITAF's specific role. I was interested in further characterizing LITAF and its implications in protein degradation and a neurodegenerative disorder. At least 9 mutations of LITAF are associated with Charcot-Marie-Tooth disease type 1C (CMT1C), which belongs to the group of most common heritable neuromuscular disorders, affecting approximately one in 2500 people. We show that LITAF mutants G112S and W116G mislocalize from the late endosome/lysosome to the mitochondria while the T49M and P135T mutants show partial mislocalization with a portion of the protein present in the late endosome/lysosome and a portion of the protein localized to the mitochondria. Since LITAF is believed to play a role in protein degradation, it is possible that the specific characteristics of CMT1C may occur though impaired degradation of Schwann cell membrane proteins, such as PMP22. I was able to show that when WT LITAF is present, there is a decrease in the PMP22 intracellular levels, which suggest that LITAF plays an important role in protein degradation, and also in other types of CMT. Insight into how mutations in LITAF cause CMT1C may not only help better understand cellular pathways, but also further elucidate the role LITAF's viral homolog FV3 75L during viral infection. Author Keywords: 75L, Charcot-Marie-Tooth, CMTC1, ER, FV3, LITAF
Exonic Trinucleotide Microsatellites
Trinucleotide repeats (TNRs) are a class of highly polymorphic microsatellites which occur in neutral and non-neutral loci and may provide utility for individual- and population-identification. Exonic trinucleotide motifs, in particular, offer additional advantages for non-human species that typically utilize dinucleotide microsatellite loci. Specifically, the reduction of technical artifacts, greater separation of alleles and greater specificity of amplification products leading to more efficient multiplexing and cross-taxa utilization. This study aims to identify and characterize polymorphic trinucleotide repeats and conserved primer sequences which are conserved across Cervidae (deer) species and their potential for individual identification in forensic wildlife investigations. Chapter one provides a broad introduction to trinucleotide microsatellites, chapter two deals with data-mining TNRs and chapter three applies the identified TNRs as genetic markers for individual identification. Results demonstrate proof-of-concept that exonic TNRs are capable of giving random match probabilities low enough to be employed in individual identification of evidentiary samples. Author Keywords: DNA typing, Exons, Genetic Markers, Individual Identification, Trinucleotide, Wildlife Forensics
NMR and EPR Studies on Cytochrome b5 Isotypes of Giardia intestinalis
The amitochondrial protozoan, Giardia intestinalis, encodes four members of the cytochrome b5 (CYTB5) family of heme proteins of unknown function. While homology models can predict the likely fold of these proteins, supporting experimental evidence is lacking. The small size of the cytochromes (~16 kDa) makes them attractive targets for structural analysis by Electron Paramagnetic Resonance spectroscopy (EPR) and Nuclear Magnetic Resonance spectroscopy (NMR). EPR measurements are particularly useful in defining the geometry of the coordination environment of the heme iron; such measurements indicated that the planar imidazole rings of the invariant histidine axial ligands are nearly perpendicular to each other, rather than in the coplanar orientation observed within mammalian CYTB5s. This may be due to geometrical constraints imposed by a one-residue shorter spacing between the ligand pair in the Giardia cytochromes b5 (gCYTB5s). Following optimization of sample and instrument conditions for NMR experiments, a comparison of the 1D 1H-NMR spectra of gCYTB5 isotype I to those of three of its heme-pocket mutants (Tyr51→Phe, Tyr61→F, and Cys84→Ala) were used to tentatively assign the heme methyl and vinyl protons. Mutant Tyr61→F had the greatest effect on the wild-type spectrum due to maximum through-space contacts with the heme macrocycle and its proximity to the His63 axial ligand. These experiments are a prelude to further NMR experiments that can lead to solving the complete structures of these proteins. Author Keywords: cytochrome b5, heme b, mutant protein, paramagnetic iron, resonant spectroscopy, sequence homology
Development of genetic profiles for paternity analysis and individual identification of the North Atlantic right whale (Eubalaena glacialis)
The endangered North Atlantic right whale (Eubalaena glacialis) has been internationally protected from whaling since 1935 but recovery has been slow compared to the southern right whale (Eubalaena australis) due to anthropogenic mortalities and poor reproduction. Prey availability, genetic variability, and alleles of genes associated with reproductive dysfunction have been hypothesized to contribute to low calf production. The North Atlantic Right Whale DNA Bank and Database contains 1168 samples from 603 individuals. I added 115 new genetic profiles to the database which now contains profiles for 81% of individuals alive since 1980. Paternity assignments using these profiles resulted in 62% of sampled calves being assigned a father and only 38% of candidate males being assigned a paternity. This may suggest false exclusion due to genotyping errors or the existence of an unknown group of males. The use of the DNA database allowed for the identification of 10 deceased individuals which has implications for identifying cause of death and reducing mortalities. However, genetic identification is dependent on the time of post-mortem sample collection which influences DNA quantity and quality. An assessment for variations in methylenetetrahydrofolate reductase, a candidate gene associated with reproductive dysfunction, revealed six females heterozygous for a synonymous A/T variant in exon four which may influence reproductive success through changes in enzyme production, conformation or activity. Author Keywords: Eubalaena glacialis, Forensic Identification, Genetic Profiling, North Atlantic Right Whale, Paternity, Reproductive Dysfunction
Involvement of Endogenous Plant Hormones in The Regulatory Network of Fatty Acid Biosynthesis in Soybean Seed
The activities of phytohormones during the reproductive phase have been partially clarified in seed physiology while the biological role of plant hormones in oil accumulation during seed development has been investigated in part only. In this research, fatty acid (FA) contents and hormone profiles, including abscisic acid (ABA) and cytokinins (CKs) of seed samples in four different stages and comparing six soybean varieties have been investigated in order to examine the hypothesis that the endogenous plant hormones play important roles in FA production in soybean seeds. The FA contents increased significantly during this period while the hormone concentrations gradually declined towards the seed physical maturation. However, the interactions between FA contents and hormone profiles were complex and went beyond linear correlations. Hormone metabolism in the earlier stages of seed maturation period demonstrated numerous robust relationships with FA accumulations, as derived from several simple and multiple regression models in the determination of different FA contents. Evaluation of the effects of exogenous ABA and trans-Zeatin (tZ) on FA biosynthesis has revealed that ABA appears to be involved in the accumulations of unsaturated FAs while tZ participated in the synthesis of saturated and unsaturated FAs. Notably, the alterations of FA synthesis differ according to what exogenous hormone concentrations could be used. Author Keywords: Abscisic acid, Cytokinin, Fatty acid, Seed development, Soybean
Canid Predation of Domestic Sheep (Ovis aries) on Ontario Farms
Livestock predation by wild predators is a frequent and complicated issue, often cited as a significant factor in the decline of livestock production and justification for killing predators. Coyotes (Canis latrans) are the primary predators of sheep in Ontario. Some farms appear to be more susceptible to predation than others, despite the use of mitigation techniques. I explored land cover in the vicinity of farms as a potential influence on the level of predation, as coyote abundance and wild prey are correlated with certain habitat types. Using model competition, I show that landscape explains little variation in predation levels over all farms, but can explain 27% of variation in the percent of a flock killed. Total forest edge habitat and distance between forest patches were both positively associated with losses, suggesting a reduction in forest cover surrounding a farm puts the flock at greater risk. In addition, I tested four disruptive deterrents for effectiveness at protecting flocks. A matched-pairs analysis did not show a statistically significant benefit of these non-lethal mitigation tools. Author Keywords: Alternative Prey, Canis latrans, Coyote, Landscape, Predation Deterrents, Sheep
Calcium in the Muskoka River Watershed- Patterns, trends, the potential impact of forest harvesting and steps toward an ecosystem approach to mitigation
Decreasing lake calcium (Ca) concentration, in lakes located in base poor catchments of the Muskoka River Watershed (MRW) in south-central Ontario, is a well- established acid-rain driven legacy effect threatening the health and integrity of aquatic ecosystems that can be compounded by additional Ca removals through forest harvesting. The objectives of this thesis were to assess patterns and temporal trends in key water chemistry parameters for a set of lakes in forested catchments in the MRW in south- central Ontario, to predict the pre-industrial steady state lake Ca concentration and the potential impact of harvesting on lake Ca levels in lakes located in managed MRW Crown forests, and to assess potential effects of various mitigation strategies in Ca depleted managed forests. Mean lake Ca (mg L-1) in 104 lakes across the MRW have decreased by 30% since the 1980's with the rate of decrease slowing over time. Mean Lake SO4 (mg L-1), and Mg (mg L-1) concentration also decreased significantly with time (37% and 29%, respectively) again with a declining rate of decrease, while mean lake pH and DOC increased significantly between the 1980's and the 1990's (16% and 12%, respectively) but exhibited no significant pattern after that. Principal components and GIS spatial analyses of 75 lakes with data from 2011 or 2012 water seasons suggested that smaller lakes, at higher elevation in smaller catchments with higher runoff and minimally impacted by the influence of roads and agriculture are associated with lower Ca concentrations and thus are the lakes at risk of amplified Ca depletion from forest harvesting. Spatial analyses of harvested catchments indicated that, under the proposed 10 year land forest management cut volumes, 38% of 364 lakes in the MRW will fall below the critical 1 mg L-1 Ca threshold compared with 8% in the absence of future harvesting. With respect to potential mitigation measures, soil pH and foliar Ca were indicated by meta-analysis to be more responsive to lime addition studies while soil base saturation and tree growth appeared more responsive to wood-ash addition. Future research should address the spatial extent of lakes at risk and identify when critical levels will be reached under harvesting regimes. Further investigation into the use of Ca-addition as a tool for managing the cumulative effects of past, present and future stressors is recommended. Author Keywords: calcium, harvesting, lakes, lime, Muskoka River Watershed, wood-ash
Understanding the establishment of Typha spp. in North America using population genetics and common garden studies
There are three cattail (Typha) taxa in Canada: T. latifolia (native), T. angustifolia (introduced), and their hybrid T. x glauca. The latter is invasive in regions around the Laurentian Great Lakes, and I investigated the potential role that commercial suppliers may be playing in the introduction of non-native Typha by comparing genotypes of North American, European, and commercially available plants. I found that Ontario garden centres are importing both hybrids and non-native lineages of T. angustifolia into Canada, but was unable to identify the provenance of T. latifolia. I also investigated the possibility that the hybrid cattail leaf litter shade and leachate influences germination and early growth of the parental species of the hybrids. Using three common garden experiments, I found that T. x glauca leaf litter suppresses germination rates of the three taxa. In the early seedling growth experiment, plant performance varied by taxa, and for the competition experiment there were no intra- or interspecific competition or treatment effects on the performance of plants. Overall, my research identified a potential mechanism allowing T. x glauca to dominate wetlands, and also shows that non-native lineages are being introduced into Canada through commercial trade Author Keywords: Competition, Germination, Non-native lineages, Plant nurseries, Seedling Growth, Typha spp.
Flavohemoglobin expression in Giardia intestinalis exposed to nitrosative stress
The parasitic protist Giardia intestinalis lacks most heme proteins yet encodes a flavohemoglobin (gFlHb) that converts nitric oxide to nitrate and likely protects the cell from nitrosative stress. In this work an antibody raised against gFlHb was used to examine both changes in gFlHb expression levels and intracellular localization in Giardia in response to nitrosative stress. Giardia trophozoites exposed to stressors which either directly release nitric oxide (diethyltriamine NONOate, 1 mM) or are sources of other reactive nitrogen intermediates (sodium nitrite 20 mM or S-nitrosoglutathione, 1 or 5 mM) exhibited a 2 to 9-fold increase of gFlHb after 24 hours. Increased expression levels of gFlHb were detectable by 8 hours in S-nitrosoglutathione and diethyltriamine-NONOate-treated trophozoites, and by 12 hours after sodium nitrite exposure; these differences were likely due to differences in the rates of release of RNS from these compounds. In addition to a band of the expected size for gFlHb (52 kDa), western blots detected a second, higher molecular weight band (72 kDa) with comparable or higher intensity upon treatment with these RNS donors, which is consistent with sumoylation of gFlHb. Immunofluorescence microscopy of Giardia trophozoites detected gFlHb diffused throughout the cytoplasm and more punctuated staining along the cell membrane and between the nuclei. The punctuated staining may be due to the association of gFlHb with either peripheral vacuoles or basal bodies. Author Keywords: Flavohemoglobin, Giardia intestinalis, Nitrosative stress
Conservation Genetics of Woodland Caribou in the Central Boreal Forest of Canada
Maintaining functional connectivity among wildlife populations is important to ensure genetic diversity and evolutionary potential of declining populations, particularly when managing species at risk. The Boreal Designatable Unit (DU) of woodland caribou (Rangifer tarandus caribou) in Ontario, Manitoba, and Saskatchewan has declined in southern portions of the range because of increased human activities and has been identified as 'threatened' by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). In this dissertation, I used ten microsatellite DNA markers primarily from winter-collected fecal samples to delineate genetic structure of boreal caribou in declining portions of the range and increase understanding of the potential influence of the non-threatened Eastern Migratory DU of woodland caribou on genetic differentiation. Eastern migratory caribou are characterized by large home ranges compared to boreal caribou and migrate seasonally into portions of the Boreal DU range. A regional- and local-scale analysis using the spatial Bayesian clustering algorithm in program TESS delineated four regional clusters and 11 local clusters, with the majority of local clusters occurring along the southern periphery of the range. One of those clusters in Ontario corresponded spatially with the seasonal overlap of boreal and eastern migratory caribou and was characterized by substantial admixture, suggesting that the two DUs could be interbreeding. Next, I decoupled the impacts of historical and contemporary processes on genetic structure and found that historical processes were an important factor contributing to genetic differentiation, which may be a result of historical patterns of isolation by distance or different ancestry. Moreover, I found evidence of introgression from a currently unsampled population in northern Ontario, presumably barren-ground caribou (R. t. groenlandicus). Finally, because our analysis suggested recent processes were also responsible for genetic structure, I used a landscape genetics analysis to identify factors affecting contemporary genetic structure. Water bodies, anthropogenic disturbance, and mobility differences between the two DUs were important factors describing caribou genetic differentiation. This study provides insights on where conservation and management of caribou herds should be prioritized in threatened portions of the boreal caribou range and may have implications for future delineation of evolutionarily significant units. Author Keywords: boreal forest, genetic structure, landscape genetics, microsatellite DNA, Rangifer tarandus, woodland caribou

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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