Graduate Theses & Dissertations

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Expression of Giardia intestinalis flavoenzyme GiOR-1 and characterization of its electron transfer properties
Giardia intestinalis possesses four isotypes of cytochrome b5 (gCYTB-I-IV) that differ from their mammalian counterparts, suggesting different functions in this protozoan parasite. Although the recently discovered Giardia flavoenzyme, GiOR-1, reduces these cytochromes, its properties have not been thoroughly studied, owing to the difficulty in its expression. Here I describe successful conditions for expression of GiOR-1 using autoinduction. GiOR-1 is obtained with flavins bound as indicated by its UV-visible spectrum. Its ability to catalyze electron transfer from donors (NADH, NADPH) to acceptors (oxygen, ferricyanide, cytochrome c, gCYTB5-III) were studied in spectrophotometric rate assays. NADPH is the preferred electron donor, while cytochromes are the preferred electron acceptors. Interestingly, the His-tag used to purify gCYTB5-III decreases its reaction rate with GiOR-1, as an untagged version has slightly faster rates. These findings establish the appropriate conditions for further studies on GiOR-1, including the identification of endogenous electron acceptors. Author Keywords: Autoinduction, Cytochrome b5, Cytochrome P450 oxidoreductase, Giardia intestinalis, GiOR-1, Polyhistidine tag
Prescription Drugs
Medication used to treat human illness is one of the greatest developments in human history. In Canada, prescription drugs have been developed and made available to treat a wide variety of illnesses, from infections to heart disease and so on. Records of prescription drug fulfillment at coarse Canadian geographic scales were obtained from Health Canada in order to track the use of these drugs by the Canadian population. The obtained prescription drug fulfillment records were in a variety of inconsistent formats, including a large selection of years for which only paper tabular records were available (hard copies). In this work, we organize, digitize, proof and synthesize the full available data set of prescription drug records, from paper to final database. Extensive quality control was performed on the data before use. This data was then analyzed for temporal and spatial changes in prescription drug use across Canada from 1990-2013. In addition, one of major research areas in environmental epidemiological studies is the study of population health risk associated with exposure to ambient air pollution. Prescription drugs can moderate public health risk, by reducing the drug user's physiological symptoms and preventing acute health effects (e.g., strokes, heart attacks, etc.). The cleaned prescription drug data was considered in the context of a common model to examine its influence on the association between air pollution exposure and various health outcomes. Since, prescription drug data were available only at the provincial level, a Bayesian hierarchical model was employed to include the prescription drugs as a covariate at regional level, which were then combined to estimate the association at national level. Although further investigations are required, the study results suggest that the prescription drugs influenced the air pollution related public health risk. Author Keywords: Data, Error checking, Population health, Prescriptions
Developing Social-Emotional Competencies in Youth
Trait Emotional Intelligence (TEI) plays an important role in the health and wellness of children and adolescents. Not surprisingly, the literature on TEI and youth has expanded dramatically. Although the quality of this work continues to be uneven due to the continued proliferation of TEI-related measures with questionable psychometric features. One over-looked TEI measure in the field is the short form developed for the Emotional Quotient Inventory Youth Version (EQ-i:YV-S). The core goal of Study 1 was to examine the overall reliability and validity of the EQ-i:YV-S. The aim of Study 2 was to evaluate the utility of the EQ-i:YV-S as a measure of the effectiveness of a new school-based social and emotional learning program for elementary school students. Results from Study 1 demonstrated that the EQ-i:YV-S had good internal reliability, 6-month test-retest reliability, and convergent validity. Study 2 found that Total EI and most key EI-related dimensions had significant improvement from pretest to post test on the EQ-i:YV-S. These findings have important implications for TEI measurement in youth and the effectiveness of school-based psychoeducational programming for TEI, with the EQ-i:YV-S as a viable option for research in this area. Author Keywords: emotional intelligence, psychoeducational programming, social-emotional competencies
Prey abundance and habitat during the breeding season for Piping Plovers in the Ontario Great Lakes region
Similar to other shorebird trends around the world, the Piping Plover population (Charadrius melodus circumcinctus) is projected to decline if concerted conservation efforts are relaxed. To date, there is insufficient understanding of the connection between habitat type, prey abundance, and chick behaviour of the Piping Plover breeding population in Ontario. The aim of my thesis was to gain knowledge about prey abundance at recent and historic breeding locations, understanding how habitat influences prey abundance and chick behaviour across the Piping Plover breeding range in Ontario’s Great Lakes. The objective of my first study was to understand prey abundance across the breeding region Great Lakes of Ontario from 2018-2019, including occupied and unoccupied sites, and to quantify variation among habitats and periods of reproduction. To evaluate resources, I sampled 17 locations to compare prey abundance using invertebrate traps (n= 3,507). Sampling took place over the reproductive periods of nest initiation, post-hatch, and fledging and in four habitat types of shoreline, wrack, berm, and back dune. Occupied breeding sites had higher prey abundances, and different assemblages of invertebrate prey than unoccupied sites. Additionally, breeding sites had higher prey abundance during nest initiation and supported higher amounts of prey in shoreline and wrack habitat. The objective of my second study was to understand how habitat types influence chick behaviour. To evaluate behaviour-habitat trends, instantaneous chick observations were recorded at the four nest sites from the post-hatch to fledging stages. In total there were 23 fledged chicks that we observed across the two years. Chicks in this study spent 60.9% of their time foraging, 11.9% of the time displaying alert behaviour, 21.4% of their time resting or being brooded, and 5.9% of their time preening. Chicks spent a large proportion of time foraging in the shoreline, resting in the back dune, and alert in berm habitat. The frequency of these alert, defensive behaviours differed among sites, with Sauble Beach chicks spending more time in defensive behaviours compared to other sites. I concluded that in both nesting and brood-rearing periods, habitat is selected non-randomly by adult and young Piping Plovers to maximize access to invertebrate prey for growth and survival. Access by chicks to the most productive habitats should be considered in local management decisions. Author Keywords: chick behaviour, endangered, Great Lakes Region, habitat, Piping Plovers, prey abundance
Sensitivity of Forest Soils to Acidic Deposition Downwind of an Aluminum Smelter, Kitimat, B.C.
Maximum permitted SO2 emissions from an aluminum smelter in Kitimat, B.C., increased after modernization in 2015. An increase in acidic deposition can potentially acidify forest soils. Monitoring was conducted at two long-term soil monitoring plots at near (7 km) and far (41 km) sites downwind from the smelter. Change in soil properties was assessed between 2015 and 2018: for the near plot, there was significant decrease in pH and exchange acidity; far plot soils exhibited significant decrease of base cations and exchange acidity in the 0–5 cm layer only. The average total SO42- deposition at near and far plots were estimated to be between 8.2–12.1 and 6.7–7.4 kg/ha/yr, respectively. It was concluded no soil acidification was detected. Observed changes were attributed to measured differences in organic matter, likely influenced by sampling difficulty and measurement process discrepancies. Estimated SO42- deposition levels pose no risk to soil base cation depletion. Author Keywords: acid forest soils, acidic deposition, aluminum smelter, exchangeable base cations, long-term monitoring, minimum detectable change
Assessing effects and fate of environmental contaminants in invasive, native, and endangered macrophytes
Macrophytes play an important role in aquatic ecosystems, and thus are integral to ecological risk assessments of environmental contaminants. In this dissertation, I address gaps in the assessments of contaminant fate and effects in macrophytes, with focus on glyphosate herbicide use for invasive plant control. First, I evaluated the suitability of Typha as future standard test species to represent emergent macrophytes in risk assessments. I concluded that Typha is ecologically relevant, straight-forward to grow, and its sensitivity can be assessed with various morphological and physiological endpoints. Second, I assessed effects from glyphosate (Roundup WeatherMAX® formulation) spray drift exposure on emergent non-target macrophytes. I performed toxicity tests with five taxa, Phragmites australis, Typha × glauca, Typha latifolia, Ammannia robusta, and Sida hermaphrodita, which in Canada collectively represent invasive, native, and endangered species. I found significant differences in glyphosate sensitivity among genera, and all species’ growth was adversely affected at concentrations as low as 0.1% (0.54 g/L), much below the currently used rate (5%, 27 g/L). Third, I assessed the potential for glyphosate accumulation in and release from treated plant tissues. I found that P. australis and T. × glauca accumulate glyphosate following spray treatment, and that accumulated glyphosate can leach out of treated plant tissues upon their submergence in water. Finally, I assessed effects of released glyphosate on non-target macrophytes. I found that P. australis and T. × glauca leachate containing glyphosate residues can stimulate the germination and seedling growth of T. latifolia, but can exert an inhibiting effect on A. robusta, although leachate without glyphosate caused similar responses in both plants. Additionally, I found no negative effects in A. robusta when exposed to glyphosate residues in surface water, or when grown with rhizosphere contact to an invasive plant that was wicked (touched) with glyphosate. My results show that non-target macrophytes can be at risk from glyphosate spray for invasive plant control, but risks can be mitigated through informed ecosystem management activities, such as targeted wick-applications or removing plant litter. Integrating contaminant fate and effect assessments with emergent macrophytes into ecological risk assessments can support the protection of diverse macrophyte communities. Author Keywords: Ecosystem management, Ecotoxicology, Glyphosate, Herbicide, Invasive plant, Species at risk
Robust assessment of changes in wild mammal occupancy and activity relative to livestock and human disturbance
Anthropogenic activities such as human activity and livestock grazing are responsible for the global rise in disturbance impacts on wildlife and may underlie regional changes in biodiversity and ecosystem dynamics. Few studies have tried to disentangle the effects of different anthropogenic activities on wildlife behaviour, leaving a major gap in our understanding of conservation and management needs in disturbed areas. Human activity and livestock grazing are increasing in spread and intensity worldwide, thereby imposing pressure on both wildlife and natural areas. In this thesis, I used a camera trapping and occupancy modeling framework to assess whether human presence and livestock grazing had different impacts on site occupancy and activity of 10 wild mammal species, and how responses differed across taxa. Specifically, I predicted that all species would be sensitive to disturbance, but the type and intensity of the response would depend on disturbance type. I detected different responses to each disturbance type across species, but response type (displacement, activity change, crepuscularity) was not associated with species characteristics such as body. Importantly, disturbance intensity had a strong effect on wildlife activity levels, with many species exhibiting marked reductions in activity at high human or livestock disturbance intensity. It remains unclear whether all species’ responses are a direct consequence of disturbance versus indirect outcomes of shifts in behaviour of other species in the wildlife community (i.e., disturbance-related changes in prey activity may affect predator activity). Although on the whole disturbance intensity and effect sizes tended to be relatively low in this study, responses were exhibited across all species, implying that disturbance responses may be universal in wild mammals and largely underestimated. Ultimately, my work offers a template for the robust assessment of disturbance impacts on wildlife and provides new avenues for future research to deepen our understanding of wildlife sensitivity to anthropogenic activities. Author Keywords: activity, anthropogenic disturbance, human activity, livestock, occupancy, wildlife
Individual Differences in Human Tolerance for Wildlife and The Role of Nature Relatedness
Human-wildlife interactions are inevitable and lead to decisions about wildlife. The current research investigated what demographic and psychological factors influence decisions in wildlife management. Also, a new measure, the Tolerance for Wildlife Scale, was developed. A student sample (n = 329) and a community sample (n = 213) completed measures on their nature relatedness, environmental concern, and emotions towards wildlife. They completed the Tolerance for Wildlife Scale and rated decisions to use lethal or non-lethal action in nine human-wildlife scenarios. Correlation analyses revealed people who are more tolerant towards wildlife are more connected with nature, concerned for the environment, feel positive emotions towards wildlife, and are more likely to choose non-lethal management actions. ANOVAs revealed that location and occupation have an impact on tolerance for wildlife. By identifying factors that influence tolerance for wildlife, humans can hope to share space with wildlife and foster coexistence. Author Keywords: emotion, environmental concern, nature relatedness, tolerance, wildlife, wolves
Evidence of an Interaction Between Memory Stores for Long-Term Context Fear Memory in the Rat
Memories which typically require the hippocampus (HPC) can become represented in structures outside of the HPC, and therefore resistant to HPC damage, but, the properties of these memories are poorly understood. Some research has suggested that the HPC continually contributes to memories that are resistant to hippocampal damage, and without this support, they are weaker and more susceptible to loss. However, this hypothesis has yet to be tested experimentally. We examined this possibility in rats by assessing decay and extinction of a context fear memory that had become independent of the HPC via repeated learning episodes. We found that HPC-independent context fear memories decay and extinguish faster without continued HPC support, suggesting that the HPC plays a continued role in long-term memory. We also provide new evidence of a persistent interaction between the HPC and other memory systems, which strengthens non-HPC representations so that they withstand HPC damage at longer intervals. Author Keywords: consolidation, context fear, hippocampus, memory, retrograde amnesia
Peers, Props & Play
This study examined the relation between complexity of pretend play during preschool and early academic skills two years later. Preschool children (n =19), aged 3 years, were observed during self-directed free play, which was then coded for complexity of symbolic thought with respect to symbolic agent (ability to direct self or other’s play) and symbolic substitution (abstractness of props). Children’s literacy and numeracy skills were assessed concurrently and two years later when children were 5 years old. We found that children who directed others' play compared to children who focused on their own play had higher mathematics achievement at 5 years. In addition, children who engaged in more complex object substitutions (abstract props) had better counting at 3 years and better early reading skills at 5 years than their peers, who showed few complex substitutions. Our findings suggest that encouraging specific aspects of pretend play in preschool could be a relatively simple way to promote early academic achievement. Author Keywords: Math , Play complexity, Preschool , Pretend Play, Reading
Phytohormone-enhanced heavy metal responses in Euglena gracilis
Phytohormones, Cytokinin (CK) and Abscisic acid (ABA), are best known for controlling plant growth and stress responses; but they also mediate various developmental perspectives in alga. Yet, their mode of action in algal adaptive strategies to heavy metal responses, their involvement in orchestration of phytohormone crosstalk remain largely unknown and a molecular framework of phytohormone-controlled heavy metal uptake is absent. I found that three metals known globally to contaminate aquatic ecosystems, nickel (Ni), lead (Pb), and cadmium (Cd), cause changes in the levels of endogenous CKs, ABA, auxins, and gibberellins (GAs) in the green alga Euglena gracilis. Exogenous ABA or CK (trans-zeatin) alleviated metal toxicity through improved metal uptake efficiency and the regulation of the endogenous CKs activity profiles and GAs activity. This new evidence suggests that E. gracilis possesses functional phytohormone signals and metabolic pathways that are under metal stress response. Exogenously applied ABA or CK provoked the coordinated activation of metal uptake, likely via enhanced accumulation of metal binding compounds (i.e., proline, glycine, cysteine containing peptides), which are effective for metal sequestration. Using untargeted metabolomics analysis and functional annotation, this thesis further established that, CK and ABA modified pathways and metabolites, which were mainly involved in metal acclimation and resistance. These modified metabolites that were under the influence of phytohormones in algal cells growing under metal stress conditions were associated with: lipid pathways, riboflavin metabolism, biosynthesis of cofactors/vitamin, and carbohydrate metabolism. Bioactive secondary compounds (e.g., terpenoids, alkaloids, flavonoids, carotenoids) were also modified in algal cells treated with phytohormones. The present study highlights that ABA and CKs are important regulators of algal metal accumulation/acclimation strategies based on increased metal uptake, enhanced CK metabolism, regulation of hormonal crosstalk and regulation of some core cellular metabolism pathways, all of which improve metal uptake efficiency. Finally, our results suggest that ABA and CK form a novel strategy for metal bioremediation techniques and for sourcing microalgal value-added metabolites. Author Keywords: abscisic acid, cadmium, cytokinin, Euglena gracilis, lead, nickel
Landscape fitness
Variation in habitat quality and disturbance levels can strongly influence a species’ distribution, leading to spatial variation in population density and influencing population dynamics. It is therefore critical to understand how density can lead to variability in demographic responses for effective conservation and recovery of species. My dissertation illustrates how density and spatial familial networks can be integrated together to gain a better understanding of the influence of density on population dynamics of boreal caribou. First, I created an analytical framework to assess results from empirical studies to inform spatially-explicit capture-recapture sampling design, using both simulated and empirical data from noninvasive genetic sampling of several boreal caribou populations in Alberta, Canada, which varied in range size and estimated population density. Analysis of the empirical data indicated that reduced sampling intensity had a greater impact on density estimates in smaller ranges, and the best sampling designs did not differ with estimated population density but differed between large and small population ranges. Secondly, I used parent-offspring relationships to construct familial networks of boreal caribou in Saskatchewan, Canada to inform recovery efforts. Using network measures, I assessed the contribution of individual caribou to the population with several centrality measures and then determined which measures were best suited to inform on the population demographic structure. I found substantial differences in the centrality of individuals in different local areas, highlighting the importance of analyzing familial networks at different spatial scales. The network revealed that boreal caribou in Saskatchewan form a complex, interconnected familial network. These results identified individuals presenting different fitness levels, short- and long-distance dispersing ability across the range, and can be used in support of population monitoring and recovery efforts. Finally, I used a spatial capture-recapture analytical framework with covariates to estimate spatial density of boreal woodland caribou across the Saskatchewan Boreal Plains, and then reconstructed parent-offspring relationships to create a familial network of caribou and determined whether spatial density influenced sex-specific network centrality, dispersal distance, individual reproductive success, and the pregnancy status of females. I show that caribou densitygreatly varied across the landscape and was primarily affected by landscape composition and fragmentation, and density had sex-specific influences on dispersal distance, reproductive success, and network centrality. The high density areas reflected good-quality caribou habitat, and the decreased dispersal rates and female reproductive output suggest that these remnant patches of habitat may be influencing demographic responses of caribou. Author Keywords: boreal caribou, density, familial networks, population dynamics, rangifer tarandus caribou, spatial capture-recapture

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Format: 2022/07/01