Graduate Theses & Dissertations

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Larval lake whitefish (Coregonus clupeaformis) recruitment dynamics in Lake Huron
Lake whitefish (Coregonus clupeaformis) recruitment has declined substantially in several regions of the Laurentian Great Lakes since the establishment of non-native dreissenid mussels in the early 1990’s. In Lake Huron, the reasons for the observed recruitment declines are currently unknown and there is limited knowledge about larval life stage. In our study, we determined whether larval hatching and growth rates have changed before and after dreissenid mussel invasion, and the role of several key environmental variables in influencing annual variation in larval densities. Larval fish were collected in the Fishing Islands spawning shoal during two time periods: a historical period (1976-1986) and a contemporary period (2017-2019). Larval densities and growth were lower in recent years, suggesting that recruitment is being limited at the larval life stage and that reduced food availability may be further limiting the growth during the larval stage. Annual variation of larval densities were influenced by spawning stock biomass, water levels, and dreissenid mussel presence, with higher water levels and the presence of dreissenid mussels being associated with higher larval densities. The direction of the effect of spawning stock biomass was either negative or positive depending on the model. We also found that larval density was a significant predictor of age 4 recruitment, indicating that year-class strength may be partly established at the larval life stage. Author Keywords: Coregonus clupeaformis, Great Lakes, Lake Huron, Lake whitefish, Larval, Recruitment
Cartoons Ain't Human
Why show things that aren’t people acting like people? In the field of animation, it’s a surprisingly big “why?”, because it’s a “why?” that doesn’t lead to any sort of doctrine of ontology, of inevitability, of manifest destiny, or of anything like that. But it does lead to another “why?”—“why did anthropomorphic depictions of animals and non-human entities come to define an entire era of American short-form animation?” When we think about ‘classic era’ cartoon shorts, the first names that come to mind are likely to be those of anthropomorphic animal characters—Mickey Mouse, Bugs Bunny, and a list of others so numerous that any machine Wile E. Coyote tried to build to count them all would probably explode. This can make us lose sight of the fact that human characters had their place as well in these films: Bugs and Daffy regularly tangled with Elmer Fudd; the studio that made cartoon stars of Betty Boop and Popeye produced no famous animal characters at all in its heyday. And yet, it’s the animals that steal the show in the animated shorts produced by major studios in America from the 1920s through the 1960s. Part of their appeal lies in the fact that they were useful and recognizable substitutes for humans. Without making things too ‘personal’ for the audience, they could be used to examine and deconstruct social practices in the full-speed-ahead period that took America from World War I to the war in Vietnam. Animals weren’t the only ones to get a full-on anthropomorphic treatment in these shorts. Machines and other artefacts came to life and became sites of interrogation for contemporary anxieties about the twentieth century’s ever-expanding technological infrastructure; parts of the natural world, from plant life to the weather, acted with minds of their own in ways that harken back to the earliest animistic folk beliefs. No matter when or how it’s being used, anthropomorphism in animation is a device for answering, not one big “why?”, but a lot of little “why?”s. What you’re about to read is an exploration of a few of those little “why?”s. Author Keywords: America, Animation, Anthropomorphism, Cartoons, Deconstruction, Popular Culture
Assessing factors associated with wealth and health of Ontario workers after permanent work injury
I drew on Bourdieu’s theory of capital and theorized that different forms of economic, cultural and social capital which injured workers possessed and/or acquire over their disability trajectory may affect certain outcomes of permanent impairments. Using data from a cross-sectional survey of 494 Ontario workers with permanent impairments, I measured workers’ different indicators of capital in temporal order. Hierarchical regression analyses were used to test the unique association of workers’ individual characteristics, pre-injury capital, post-injury capital, and the outcomes of permanent impairments. The results show that factors related to individual characteristics, pre-injury and post-injury capital were associated with workers’ perceived health change, whereas pre-injury and post-injury capital were most relevant factors in explaining workers’ post-injury employment status and income recovery. When looking at the significance of individual predictors, post-injury variables were most relevant in understanding the outcomes of permanent impairment. The findings suggest that many workers faced economic and health disadvantages after permanent work injury. Author Keywords: Bourdieu, hierarchical regression, theory of capital, work-related disability, workers with permanent impairments
How Did We Get Here? Exploring Socio-Political Influences in Canadian Penitentiaries
This thesis examines how political and social issues have molded and alteredCanada’s penal system since the nineteenth-century. From early Anglo-Canadian society to Joseph Archambault’s 1938 Report of the Royal Commission to Investigate the Penal System of Canada, the Canadian penal system waxed and waned against social and political tides. As rehabilitative justice took hold throughout the developed world in the early twentieth century, Canada attempted to shift its justice ideologies only to find that punitive justice had created strong footings. This made reform challenging to implement. Author Keywords: Archambault Report, Canadian penal system, Canadian prisons, prison press, prison systems, prison writing
Using Fluorescent Carbon Dots for Biosensing Applications of Amino Acids
Amino acids make up proteins, which are the building blocks of life. A balance of amino acids is needed to maintain a healthy state. Tyrosine (Tyr) is synthesized from the metabolism of phenylalanine, which is an essential amino acid, meaning it can only be obtained from the diet. It is related to many metabolic and neurodegenerative diseases. Tyr can undergo post-translational modifications such as phosphorylation and nitration, which are implicated in cancer and nitrative stress, respectively. Although there are many methods to detect Tyr and its analogues, phosphotyrosine (pTyr) and nitrotyrosine (nTyr), these methods are time-consuming, involve expensive instruments and involve tedious process. This research proposes a new type of nanomaterials, carbon dots (CDs), to detect these amnio acids. Data indicate that CDs can be used to detect nTyr with a limit of detection of 34 μM in the linear range of 20 - 105 μM. The amenability of CD-nTyr assay was also tested in various biological matrices and biological molecules and was shown to be sensitive to nTyr. Nitration of Tyr was carried out in the presence of sodium nitrite and hydrogen peroxide catalyzed by either Cu(II) or Fe(III) to mimic biological reactions and CDs were tested as both inhibitors and indicators of Tyr nitration. Although CDs did not inhibit the nitration reaction of Tyr, they did not serve as indicators of Tyr nitration due to the quenching of CDs by the nitrating agents. This shows the importance of using CDs to detect nTyr and further use it for biological applications to detect diseased states. Author Keywords: amino acids, carbon dots, nanomaterials, sensor, spectroscopy, tyrosine
Determinants of Deviance
Background: Researchers have provided evidence that attachment may be independently linked to early adversity and criminal behaviour. In this study, I examined the combined associations among these variables in a student and community sample. Method: The first study consisted of undergraduate students (n = 590) who completed surveys to assess early adversity (Felitti, et al., 1988), attachment (Scharfe, 2016), and criminal behaviours. Participants were grouped based on their reports of adverse experiences and engagement in criminal behaviour. The second study was a replication of the first using a community sample (n = 294). Results: My hypotheses were partially supported, and my findings were consistent across Study 1 and Study 2. As I expected, there was a significant main effect for adversity when examining the mean scores of the attachment representations for attachment to mothers (Study 1 F (16, 1763.402) = 3.61, p < .001; Study 2 (F (16, 849.942) = 2.377, p = .002) and attachment to fathers (Study 1 F (16, 1763.402) = 4. 349, p < .001; Study 2 (F (16, 840.776) = 3.067 p < .001)). From examining the means, I concluded that participants who reported greater adversity reported higher insecure-avoidant and lower secure attachment to mothers and fathers. There were no significant main effects for criminal behaviour or significant interaction effects. Impact: To date, no study has explored all three variables explicitly. My findings are able to highlight the critical importance of secure attachment relationships and add further comprehension to exploring factors associated to criminal behaviour. Author Keywords: Attachment, Criminal Behaviour, Early Adversity
Retrograde Amnesia of Fear Memories Following Pentylenetetrazol Kindling
Memories pertaining to fearful events are some of the most salient and long-lasting memories, as they are critical to the survival of an organism. Seizures induce aberrant changes within temporal lobe and limbic brain structures that are critical for supporting fear memories. Seizures can occur at any time; therefore, it is imperative that research address how seizures impact previously learned information. The present series of experiments demonstrate that pentylenetetrazol-kindling induces retention deficits of previously acquired context fear memories in male rats. Kindling induced subsequent fear learning deficits but did not impact spatial learning. Additionally, following kindling, volumetric increase was observed within the hippocampal subfield CA3, as well as increased neural activation within the hippocampal subfield CA1. The results of this work suggests that chronic seizures can alter the function of neural networks important for supporting and retrieving previously acquired memories. Author Keywords: amygdala, anterograde amnesia, context fear conditioning, hippocampus, retrograde amnesia, seizures
Story is Medicine
This is a story within a story that spans over a hundred years and four generations. It takes the reader from war-torn Russia during a famine to the urban streets of Toronto and then to the Canadian North. The story is a memoirette, or a ‘not quite long enough, but almost a memoir’ of a mother’s journey navigating life after her son discloses his addiction to Fentanyl. The mother finds little if any support from family, friends or conventional support programs and instead turns to her oma’s harrowing stories of survival as a source of knowledge, strength and medicine. The analysis explores storytelling as a legitimate method of learning, pedagogy and research. It explores the concept of story as medicine through Etuaptmumk. A Two-Eyed Seeing framework created by Mi’kmaq elders in 2004 (Sylliboy, Latimer, Marshall & McLeod, 2009). The power of the narrative is discussed through ‘Western’ and ‘Indigenous’ lenses. Author Keywords: addiction, Etuaptmumk, Fentanyl, story as medicine, story as pedagogy, Two-Eyed Seeing
Interactome study of the Giardia intestinalis nuclear localized cytochrome b5
Giardia intestinalis is a waterborne enteric parasite that lacks mitochondria and the capacity for heme biosynthesis. Despite this, Giardia encodes several heme proteins, including four cytochrome b5 isotypes (gCYTB5-I – IV) of unknown function. The aim of this thesis is to gain insight into the function of the Giardia cytochrome b5 isotype III (gCYTB5-III) that is found in the nucleus, as first reported by our laboratory using immunofluorescence microscopy experiments with an isotype-III specific antibody. Nuclear localization of isotype-III is supported by two of my experiments: i) immunoblot analysis of crude cytoplasmic and nuclear enriched fractions of Giardia trophozoites; ii) association of gCYTB5-III with the insoluble fraction of Giardia lysates crosslinked with formaldehyde is reversed by DNase I treatment. To gain an understanding of the possible roles of gCYTB5-III, I performed immunoprecipitation (IP) experiments on lysates from Giardia trophozoites to identify its protein partners. Mass spectroscopy analysis of the immunoprecipitate identified proteins localized to the nucleus (RNA polymerase, DNA topoisomerase, histones, and histone modifying enzymes). Intriguingly, over 40% of the known mitosomal proteome, which functions in iron-sulfur (Fe-S) cluster assembly was also associated with gCYTB5-III. One of these proteins, the flavoenzyme GiOR-1, has been shown to mediate electron transfer from NADPH to recombinant gCYTB5-III. These IP results provide evidence that GiOR-1 and gCYTB5-III interact in vivo, and furthermore, suggest that some proteins in the mitosome could interact with those in the nucleus. I also found that DNA stress, caused by low concentrations of formaldehyde (0.1 – 0.2%) resulted in the increased expression of gCYTB5-III. Collectively these findings suggest a role of gCYTB5-III in Giardia's response to DNA stress and perhaps the formation of Fe/S clusters. Author Keywords: cluster, cytochrome, heme, iron, mitosome, nuclear
Food insecurity among racialized international students
The notion that food insecurity only occurs in the absence of food is prevalent in society. This perception is too narrow and insufficient to capture the diverse manifestations and experiences of food insecurity. In this thesis, I adopt a more expansive approach to examine food (in)security through the lenses of adequacy, quality, and availability of culturally relevant food. I look specifically at the experiences of racialized international students from diverse backgrounds, to empirically ground this approach to understanding food (in)security. Drawing on both quantitative and qualitative data, this study explores the perceptions and real-life experiences of racialized international students who study at Trent University and University of Toronto. These two institutions were selected based on cultural diversity and variation, proximity to culturally appropriate food and the cost involved in accessing culturally appropriate food. Beyond that, I examine structural and policy elements that may be exacerbating the challenge of food security among this category of students. Clearly, issues related to food insecurity and hunger within all spatial configurations are urgent, however, there is a scarcity of literature that zeroes in on the experiences of racialized international students specifically. In the wake of the dramatic internationalization of post-secondary Canadian schools, issues of foreign students’ welfare cannot be overlooked, hence, I narrowed my research lenses to study the character of racialized international students’ inadequate access to culturally appropriate food. Upon analyzing the survey data gathered from 107 racialized international students coupled with semi-structured in-depth interviews with 8 racialized students, I found evidence that culturally appropriate foodstuffs were not abundant in supply for racialized international students. Consequently, the low supply of this category of foodstuffs translates into higher levels of prices which deter racialized international students from making adequate purchases to meet their taste and preference. As part of the findings, the students mentioned that the high cost of tuition, as well as other school-related expenditures are structural policy barriers that leave them with meagre amounts of income to spend on culturally appropriate food items. Under such circumstances, racialized international students are left with the option of purchasing fewer quantities of culturally relevant foodstuffs that meet their daily nutritional requirements. The study further revealed that the challenge of food insecurity poses a threat to the academic achievement and psycho-social well-being of affected students. In addressing these challenges, I propose that the government as well as the school authorities should consider reducing the tuition fees to lessen the financial burden on students. Apart from that, stocking grocery stores and creating culturally appropriate food supply centers in and around school campuses may be helpful. Also, the international offices of universities should intensify welfare programs that entail periodic needs assessment of international students. This will offer the school authorities timely support services to students as and when it is needed. In conclusion, I wish to state that this study seeks to add to the recently growing strand of literature that examines the intersectionality between internationalization of post-secondary schools and food insecurity. The findings provide important and preliminary evidence underpinning the experiences of racialized international students with the phenomenon of food insecurity, thereby providing a point of departure for additional research on the broader nature of intersections between food insecurity and racialization. Author Keywords: Canada, Culture, Food insecurity, International Students, Race, Universities
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

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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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