Theses & Dissertations - Harvested by LAC

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This collection contains all non-embargoed theses and dissertations that comply with Library and Archives Canada's (LAC) Theses Canada harvesting requirements. All theses and dissertations that are suitable for harvesting are automatically mapped into this collection and will be harvested into the Theses Canada collection.

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    Interactions between individual physiology and social information in the North American red squirrel (Tamiasciurus hudsonicus)
    (University of Guelph) Hare, Alexander; Newman, Amy; McAdam, Andrew
    As the manner in which individuals respond to, and produce social information is intimately connected to their physiological state, it is not surprising that individual physiological responses to stress as mediated through endocrine axes, such as the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes may have impacts not just on the responding individual, but on the surrounding community through social information. Despite the important role that these interactions play in shaping individual responses to stimuli, interactions between conspecifics, and resource utilization, our understanding of how these physiological axes and social information interact remains relatively uninvestigated. My thesis aims to examine the role that the HPA axis and closely associated HPG axis play in directing how social information is produced and incorporated into both the physiology and ecology of free-living mammals. In order to do this, I have conducted field experiments and examined multi-year datasets from a natural population of North American red squirrels (Tamiasciurus hudsonicus) that have been studied continuously for the last 34 years. Conducting a playback experiment in which I manipulated the motivational state and relatedness of senders, I found that receiving red squirrels did not alter territorial behaviour, indicating that the physiological state of senders is less important than other factors, such as changes in resources for kin discrimination. Second, I examined a multi-year dataset of acoustic recordings in order to examine whether there were reliable vocal cues relating to estrus in female red squirrels. Despite finding no distinct cues relating to estrus, I did find that female vocal characteristics changed significantly during pregnancy, providing potential cues to conspecifics within an acoustic neighbourhood. Finally, in examining whether social information regarding circulating glucocorticoids influenced social partners, I found that red squirrel glucocorticoids were influenced by the glucocorticoids of neighbours. I also found novel sex differences in the glucocorticoid levels of males and females. This thesis expands our understanding of how individual physiology and social information influence each other, showing strong association between both the HPA and HPG axes and the social interactions of a natural population of mammals.
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    Investigating Representations and Students’ Challenges, Experiences and Perceptions of Equity, Diversity and Inclusion at Veterinary Colleges in Canada and the USA
    (University of Guelph) Dusome, Kassandra; Khosa , Deep
    Though important, equity, diversity and inclusion (EDI) is understudied and reported in veterinary medicine. Using two studies, this research aimed to investigate the representations, and students’ challenges, experiences and perceptions of EDI at veterinary colleges. First, the websites of all veterinary colleges in Canada and the USA were assessed using content and statistical analysis. Male or BIPOC people were more likely to be depicted without animals. BIPOC individuals were under-depicted on some USA websites and over-depicted on others. Website reading level, and access to supports for underrepresented students and mental health resources were inconsistently represented. Second, the survey responses of students at five Canadian and five American colleges were statistically analyzed. Students who were not white, with a disability or part of the LGBTQ2S+ community were more likely to agree or strongly agree that discrimination occurs at college. Overall, fewer students reported experiencing discrimination in colleges compared to workplaces.
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    Plant response to severing access to arbuscular mycorrhizal networks differs between controlled and field environments
    (University of Guelph) Herlin, Olivier; Maherali, Hafiz
    Arbuscular mycorrhizal (AM) fungi associate with 70% of plant species and increase the availability of nutrients in exchange for plant sugars. Research determining whether plants benefit from AM fungi is derived predominantly from controlled environments that may not represent the undisturbed field environment. To determine whether plant responses are equivalent between controlled greenhouse and field environments, we quantified 9 plant species responses to severing access to the AM network in both environments using a mesh barrier (48μm) preventing root entry but enabling ingrowth of AM hyphae. We found that in the greenhouse severing access to AM networks reduced plant biomass, but in the field severing increased plant biomass. The lack of correlation in plant mycorrhizal responsiveness between environments suggests that controlled environments may need to account for the surrounding plant density, plant community, and the larger carbon cost from AM networks in the field to observe field relevant plant responses.
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    Novel Roles of Cardiac-derived Erythropoietin in Disease
    (University of Guelph) Marrow, Jade P.; Simpson, Jeremy
    Myocardial infarction (MI) is a leading cause of death globally. Over 3 million individuals experience ST-segment elevation MI (STEMI) each year. Despite considerable research into cytoprotective mechanisms, no clinically available therapy has been developed that directly reduces ischemic cardiac injury. Understanding the pathophysiological mechanisms underlying MI should reveal novel strategies for treatment and diagnostic purposes (i.e., biomarkers). Emerging preclinical data shows erythropoietin (EPO), a canonically renal-derived erythropoietic cytokine, is also produced by the heart under hypoxic conditions in vitro and in vivo. However, whether these findings translate to functionally relevant outcomes post-MI is currently unknown. Therefore, the overarching purpose of this thesis was to define the contributions to cardioprotection by endogenously produced EPO in the heart and fundamentally improve our understanding of non-canonical EPO biology. My objective was to characterize the systemic (i.e., endocrine) and local (i.e., autocrine/paracrine) effects of cardiac EPO using two in vivo pre-clinical models (i.e., murine permanent occlusion MI and a cardiomyocyte-specific EPO knockout mouse). We hypothesized: 1) cardiac ischemia localized to the heart would induce cardiac Epo expression and contribute to erythropoiesis, and 2) loss of endogenous cardiomyocyte-derived Epo would increase myocardial susceptibility to ischemia-reperfusion injury and impair cardiac functional recovery. Here we show MI upregulates cardiac Epo, stimulating erythropoiesis, alongside the expression of a novel exon 4-deleted Epo splice variant (termed mV-Epo). Administration of recombinant human EPO (rhEPO) or a human orthologue to the mV-EPO variant (hV-EPO) was cardioprotective compared to vehicle-treated MI mice. Therefore, as a non-erythropoietic EPO isoform, hV-EPO represents a promising strategy for amplifying endogenous cardiac EPO signaling in post-MI patients without the rheological side effects posed by traditional rhEPOs. In our second model, cardiomyocyte-specific Epo deletion induced a compensatory increase in Epo expression by neighboring endothelial cells that enabled cellular hypertrophy and superior cardiac function, and reduced ischemia-reperfusion injury. Collectively, cardiac EPO has powerful physiological relevance as a cardioprotectant and erythropoietic cytokine. These findings fundamentally shift our understanding of EPO biology – confirming it as both an endocrine and autocrine/paracrine cardiac hormone – and reinvigorate its therapeutic potential for ameliorating MI-induced dysfunction.
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    Growing tomato in controlled environments under continuous light requires dynamic LEDs to entrain the circadian rhythm, adjust canopy architecture, and balance photostasis
    (University of Guelph) Marie, Telesphore; Grodzinski, Bernard
    Controlled environment agriculture (CEA), including greenhouses and indoor production, offers tremendous opportunities to meet food security across the world. The success of CEA depends on electricity, with artificial lighting consuming a large fraction. Previous work has introduced a novel alternating LED strategy that extends the photoperiod in greenhouse production, taking advantage of off-peak electrical pricing while maintaining a healthy crop. Tomato (Solanum lycopersicum L.) is a model species in terms of its sensitivity to extended photoperiods, experiencing photoperiodic injury under continuous light. The alternating LED strategy alleviated photoperiodic injury and it was hypothesized that circadian rhythm entrainment was responsible, as the injury itself has been associated with circadian asynchrony previously. The presented thesis continues to explore and optimize the strategy in different chapters. First, the principles of circadian entrainment are detailed. A perspective centers on the “latitudinal rule”, where predictable chronotypes have evolved to the longer photoperiods in northern latitudes that can guide selectable traits for breeders and tailor ideal entraining cues for any genotype. Second, diurnal transpiration patterns revealed a great way to assess and measure circadian entrainment on a whole-plant level as they integrate cellular-stomata responses with whole-plant hydraulic status. Practically, transpiration, and associated thermal indices, can be sensed remotely to bring circadian data into smart-agriculture. Finally, a modified dynamic LED strategy (dynamic 1) significantly outperformed control (16hr photoperiod with unchanging spectrum), and by-far surpassed constant light (24hr), in total biomass accumulation via morphological and photosynthetic adjustments. A second modification (dynamic 2) attempted to extend the daytime photoperiod by 4hrs and resulted in a subtle photosynthetic stress response. A deep phenotyping gas exchange plus chlorophyll fluorescence multi-curve dataset revealed photorespiration as both beneficial and hazardous in photoperiodic injury. Also, a simple high throughput protocol distinguished dynamic 2 as engaging a nonphotochemical quenching dissipative type response, whereas dynamic 1 engaged an ATP:NADPH balancing response that upregulated ATP synthase activity. Cyclic electron flow at nighttime was also found to likely contribute much needed ATP. Overall, a philosophy is proposed that optimizing plant growth should start with entraining circadian rhythms, and then fine-tune timing/ dosage to choreograph morphology and balance photostasis.
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    Transferable skills: A student perspective
    (University of Guelph) Boivin, Simone; Jacobs, Shoshanah
    University graduates do not have the necessary skills to succeed in the workplace. To address this skills gap there have been calls for universities to improve transferable skill education. To accomplish this, it is important to understand students’ attitudes and motivations. To better understand Canadian undergraduate students’ attitudes about and motivation to develop transferable skills in their education I created and distributed a survey to students at the University of Guelph in all disciplines and year levels. I also developed and delivered a scientific inquiry workshop, delivered in two different contexts (biology-specific, and general). I found that students in all year levels have a positive attitude about and are motivated to develop transferable skills, with students mostly focused on the value of transferable skills for employment. Students are also frustrated with current transferable skill education. There is also indication that students feel differently about developing transferable skills in different contexts.
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    How to Market Your Curator Team: The Role of Entitativity in Curation Subscriptions
    (University of Guelph) Wang, Huiquan; Wang, Juan
    Curation subscription is an emerging e-commerce business model which provides recurring deliveries of products selected by curators from companies but tailored to subscribers’ individual preferences. Focusing on the essential role of curators in curation subscriptions, the current research explores how subscription companies promote their curation services by managing the entitativity of their curator teams. Results from one study indicate that increasing the entitativity of a curator team can increase the perceived competence of the team, which in turn promotes consumers’ subscription intention. The positive effect of entitativity on subscription intention only presents for consumers with utilitarian purchase motivations. As consumers’ purchase motivations shift from utilitarian to hedonic, the effect attenuates to disappears. Findings of the study provide theoretical implications for future marketing research as well as managerial inspirations for subscription service providers.
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    Analysis of the Immunomodulatory Properties of Mycobacterium Cell Wall Fraction on the Cytokine Production of Peripheral Blood Mononuclear Cells of Healthy Dogs
    (University of Guelph) Ward, Robert; Sharif, Shayan; Geoffrey, Wood; Khalil, Karimi; Charlotte, Pye; Anthony, Yu
    Mycobacterium cell wall fraction (MCWF) is a Toll-like receptor agonist that is derived from non-pathogenic Mycobacterium phlei. The objective of this research was to evaluate host responses induced by MCWF in canine peripheral blood mononuclear cells (PBMCs), using enzyme-linked immunosorbent assays (ELISA) and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) for quantifying cytokine protein and mRNA transcripts, respectively. PBMCs were isolated from eight healthy dogs and cells were cultured with MCWF. A significant increase of interleukin (IL)-10 mRNA was detected at all time points for all concentrations of MCWF (p<0.05). mRNA relative abundance reflected this finding. A post-stimulation elevation of interferon (IFN)-γ mRNA was noted at 24-hours with all concentrations of MCWF (p<0.01) and tumor necrosis factor (TNF)-α mRNA was increased for 0.5ng/dL MCWF only at 72-hours (p<0.05) compared to the negative control. Further research into the role of MCWF as a systemically administered immunomodulator or adjuvant to immunotherapy is warranted.
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    Treated with Love: Understanding Dog and Cat Caregivers’ Perceptions, Decisions, and Experiences with Feeding Treats
    (University of Guelph) Nielson, Shelby; Khosa, Deep
    Treats are commonly fed by most dog and cat caregivers and can constitute a significant proportion of an animal’s diet, potentially contributing to obesity. Previous research has explored the nutritional aspects of the primary diet for companion animals, though factors surrounding treat feeding specifically have received far less attention. While reducing or eliminating treats is commonly recommended as a strategy for weight management, caregivers can struggle to adhere to such dietary recommendations. This research consisted of two sequential phases using a mixed-methods approach. The first phase utilized an online questionnaire to quantitatively explore dog and cat caregivers’ (n=1053) perceptions, decisions, and behaviours for feeding treats. Data were analyzed using descriptive statistics and multivariable modelling, and results were used to inform the development of a question guide for the subsequent qualitative phase. The second phase involved the use of five online focus groups to provide an in-depth exploration of caregivers’ (n=24) perceptions and behaviours surrounding treat feeding, including their motivations and barriers related to reducing treat feeding with dogs and cats. Findings elucidated a diverse spectrum of how caregivers incorporate treats in their pet’s diets, evident through a multitude of treat types, as well as how and why treats are provided. The research identified associations between certain treat feeding habits and obesity, including daily chews (OR=2.99) for dogs and table scraps (OR=4.22) for cats. Findings highlighted the importance of treats in the human-animal bond, which can influence caregivers’ willingness and capability to deny treats. Changing the pet’s routine (OR=1.67) was identified as a significant factor that was positively associated with caregivers’ reported capability to reduce their pet’s current treat intake as difficult. Overall, participating caregivers reported a low reliance on veterinarians for support in decisions and habits related to feeding treats. Outcomes of this research have both clinical and educational implications, offering a foundational framework for the development of targeted interventions. Findings highlight opportunities to enhance the available resources that can empower both veterinary professionals and caregivers to make well-informed decisions and foster sustainable treat feeding practices to support weight management and overall health, while fostering the human-animal bond.
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    Histological Heterogeneity: Tissue-Level Diversity of Lizard Osteoderms
    (University of Guelph) Willan, Gabriella; Vickaryous, Matthew
    Osteoderms are bone-rich elements that form within the dermis of various vertebrates including many species of lizard. Lizard osteoderms demonstrate variability in size, shape, and body-wide distribution but a detailed comparative assessment of their microstructure is lacking. Here, I characterized the histological diversity of osteoderms from representative members of the lizard groups Gekkota (geckos), Scincomorpha (scincids, cordylids, Gerrhosaurids), and Anguimorpha (anguids, Shinisaurus, helodermatids, varanids). In virtually all lizards, osteoderms are composed primarily of bone, albeit with a heterogeneous and often laminated fibrillary organization. Histologically, most osteoderms are dominated by lamellar, woven-fibred, and/or Sharpey-fibred bone, although details of the organization and relative contribution of each bone matrix differs between genera. In addition, we found that multiple genera from each major group also develop a highly mineralized, collagen and cell-poor capping tissue – a feature previously restricted to only a handful of species. Singularly, the osteoderm-like elements from the gekkotan Geckolepis entirely lack bone and instead are composed of a plate of collagen topped with mineralized capping tissue.
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    Glucose-Induced Memory Enhancement Mediated by Opioid Systems in Rats
    (University of Guelph) Soodeen, Keith; Leri, Francesco
    The mechanism of the memory enhancing effects of peripheral administered glucose is not well understood. This line of research is important because it may offer insight into food addictive seeking behaviours and obesity. The aim of the current study was to investigate the effect of subcutaneous glucose injections on memory consolidation and if the memory enhancement could be blocked by modulating the opioid or catecholamine systems. In this study, male Sprague-Dawley rats were tested on object recognition with post-training administration of glucose as well as with post-training administration of a contrave-like drug combination and glucose. It was found that glucose (100mg/kg) enhancing effect on object recognition tasks could be blocked with the contrave-like combination, naltrexone alone, and naloxone methiodide. This experiment concluded that opioid receptors are involved with the memory enhancement from glucose.
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    Analysis of Stx4-Munc18c Interaction and Membrane-Type 1 Matrix Metalloproteinase Phosphorylation During Cell Invasion
    (University of Guelph) Battagin, Samantha; Coppolino, Marc
    Membrane-type 1 matrix metalloproteinase (MT1-MMP) plays a central role during invadopodium-based ECM degradation and subsequent cancer cell invasion through its proteolytic ability and as a signal transducer. Regulation of MT1-MMP function is not well understood but would provide better insight on the role of MT1-MMP and how it can be targeted to impair cell invasion in metastatic cancers. Previous research provides evidence that disrupting SNARE function, by competitively inhibiting Stx4’s interaction with its regulatory protein Munc18c, impairs MT1-MMP trafficking and cell invasion. Furthermore, previous research revealed a potential role for MT1-MMP phosphorylation at Thr567 in the activation of ERK signalling as a mechanism to upregulate cell invasion. The goal of this study was to examine Stx4 and Munc18c interaction across different breast cancer cell lines and to determine if ERK activation in breast cancer cells is mediated by MT1-MMP phosphorylation. The results of this study suggest Stx4-Munc18c interaction is conserved across breast cancer cell lines and in breast tumour tissues. Although we could not conclude the involvement of MT1-MMP phosphorylation at Thr567, our results confirm positive evidence of MT1-MMP’s potential role in ERK activation. This study expands the analysis on cellular mechanisms involved in regulating MT1-MMP activity.
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    Barbering in Laboratory Mice (Mus musculus): Investigating Risk Factors and Behavioural Correlates
    (University of Guelph) Young, Lauren; Mason, Georgia
    Barbering is a behaviour in laboratory mice (mus musculus), where animals pluck the fur and/or whiskers out of themselves or conspecifics. It has been hypothesized this behaviour is related to social dominance, human hair-plucking disorders (trichotillomania) and environmental stressors, though there is no consensus in the literature. I sought to replicate past findings about environmental and demographic factors that increase the risk of whisker- and fur-barbering and test new hypotheses using a cross-sectional data collection approach. I also sought to simultaneously test three hypotheses about the etiology of whisker-barbering using time budget data. Overall, this work found differential factors that increase the risk of whisker- and fur-barbering. It also suggested that whisker-barbering in female C57BL/6 mice is related to social dominance, though only in older animals, and is reduced by environmental “enrichment”. Further research is thus needed to investigate the influences on, and welfare impacts of, different barbering phenotypes.
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    Unlocking the Potential of Fat in Milk Replacer for Calves
    (University of Guelph) Wilms, Juliette Nina Roxanne; Steele, Michael
    The composition of milk from mammals likely evolved to ensure the survival and the optimal growth of the offspring. In the dairy industry, calves are often fed milk replacer (MR) or a combination of whole milk (WM) and MR. Despite advances in calf nutrition, MR still significantly differs from WM, particularly in fat content, which is half that of WM. Competition within the food industry also results in milk fat being unavailable for inclusion in MR formulations, requiring the use of alternative fat sources. Since nutrient imbalances can disrupt metabolic homeostasis in neonates, it is important to establish nutritional boundaries for MR formulation. To address these challenges, the objectives of this thesis were to 1) understand the impact of low-fat formulations on calf development and metabolic responses, 2) to investigate to which extent fat composition in WM and MR is important for the developing calf, and 3) to propose short-term improvement in fat composition by balancing individual fatty acids (FA) to enhance the well-being of calves in current production systems. All experimental analyses were performed on Holstein dairy calves within the first 3 mo of life. Calves were raised in two systems: individually housed and fed restricted volumes of milk or group-housed with ad libitum access to milk and starter feed. Unlike MR high in lactose or protein, increasing fat inclusion in MR shifted metabolic responses closer to those of calves fed a WM powder. Formulating the FA profile to resemble milk fat by incorporating dairy cream was beneficial for calves, improving preweaning intakes and growth. Finally, balancing individual FA in MR, as a means to further mimic the FA profile of milk fat without including dairy cream, improved gastrointestinal tract development in the preweaning phase, allowing calves to consume substantially more starter feed upon weaning. Taken together, these findings suggest that increasing the fat content and balancing the fat composition in MR is crucial for enhancing the growth and metabolic health of developing calves.
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    Characterizing and Improving the Light Environment in Greenhouse Fruiting Vegetable Crops
    (University of Guelph) Terlizzese, Daniel; Zheng, Youbin
    During the winter, a lack of natural light significantly impairs greenhouse crop production. To use light more efficiently, this thesis investigated the light environment and photosynthetic capacities of leaves throughout the canopies of greenhouse-grown eggplant (Solanum melongena) and mini cucumber (Cucumis sativus). The effects of supplemental lighting with extended photoperiods on greenhouse eggplant were also explored to reduce energy costs. Within both species’ canopies, the greatest decrease in light intensity was observed between 0.0 - 0.4 m from the canopy apex, but leaves remained photosynthetically active throughout the canopy. Thus, pruning healthy leaves between 0.0 - 1.0 m from the canopy apex will not increase net carbon assimilation. All photoperiods with supplemental lighting produced similar fruit yields, but early signs of plant stress were observed within the 20h treatment. This thesis provides valuable information to guide the management of greenhouse vegetable crops while decreasing the energy cost of supplemental lighting.
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    Novel Strategies for Sustainable Rapid Breeding of Cannabis sativa L.
    (University of Guelph) Baiton, Austin; Jones, Andrew
    Currently, feminized cannabis seeds are produced by spraying “XX” plants with silver-based compounds to block ethylene receptors. 1-MCP provides a more environmentally benign alternative to silver. Exposure to 100µM gaseous 1-MCP for 72 hours resulted in a 30.4% conversion to male flowers compared to 72.6% for the 3mM STS (silver thiosulfate) treatments. The use of in-vitro plants to reduce generation time is also investigated. In-vitro cannabis explants treated with 10µM PBZ (paclobutrazol) had increased harvest index (HI) (30.8%) and floral weight (135mg/plant) compared to the control with 15.8% HI and 60mg floral weight. No treatment induced a more rapid transition to flowering compared to the control. Lastly, polyploidy is explored as a method of crop improvement. The tetraploids matured 20 days before the diploids and produced the same amount of floral material calculated as grams short day-1 with 3.43g day-1 in diploid plants and 3.62g day-1 for tetraploids.
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    Loss of Nkd1 is Dominant to Loss of Axin2 in Regulating Wnt Signaling
    (University of Guelph) Bell, Ian; Van Raay, Terry
    Canonical Wnt signaling is a crucial regulatory pathway in early embryonic development and adult stem cell maintenance and its misregulation leads to numerous diseases. Thus, understanding the regulation of this pathway becomes vitally important. The canonical Wnt pathway signals through the stabilization of β-catenin in the cytoplasm allowing for β-catenin to relocate to the nucleus to activate Wnt target genes. Axin2 and Nkd1 are widely utilized negative feedback regulators in Wnt signaling where Axin2 functions to destabilize cytoplasmic β-catenin, and Nkd1 functions to inhibit the nuclear localization of β-catenin. Here, we set out to further understand how Axin2 and Nkd1 regulate Wnt signaling by creating axin2-/- and nkd1-/- single mutants and axin2-/-;nkd1-/- double mutant zebrafish using sgRNA/Cas9. All three Wnt regulator mutants were viable and had impaired heart looping, neuromast migration defects, and behavioral abnormalities in common, but there were no signs of synergy in the axin2-/-;nkd1-/- double mutants. Further, Wnt target gene expression by qRT-PCR and RNA-seq analysis, and protein expression by mass spectrometry demonstrated that the axin2-/-;nkd1-/- double mutant resembled the nkd1-/- phenotype, suggesting that loss of Nkd1 is dominant over the loss of Axin2. In support of this, the data further demonstrates that Axin2 uniquely alters the properties of β-catenin-dependent transcription, having novel readouts of Wnt activity compared to nkd1-/- or the axin2-/-;nkd1-/- double mutant. We also tested the sensitivity of the Wnt regulator mutants to exacerbated Wnt signaling, where the single mutants displayed characteristic heightened Wnt sensitivity, resulting in an eyeless phenotype. Surprisingly, this phenotype was rescued in the double mutant, where we speculate that cross-talk between Wnt/β-catenin and Wnt/Planar cell polarity pathways could lead to altered Wnt signaling in some scenarios. Collectively, the data emphasizes both the commonality and the complexity in the feedback regulation of Wnt signaling.
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    Establishing a Model System for Studying the Role of CREB3 in Insulin Secretion from Pancreatic Beta Cells
    (University of Guelph) Chiu, Brian; Lu, Ray
    CREB3/Luman is a transcription factor that is best known for its involvement in the unfolded protein response. Little is known about Luman’s role in insulin secretion, but it has been shown to be involved in a variety of secretory and metabolic processes such as COPII vesicle formation and regulation of glucose transporter expression. Insulin is a peptide hormone responsible for lowering blood glucose in the body. It acts through the promotion of glucose uptake and storage by suppression of glucose production. The pancreatic beta-cell is the sole cell type in the body responsible for both insulin production and secretion and will recognize extracellular glucose concentration and secrete the insulin needed to maintain proper glucose homeostasis. Failure to maintain proper glucose homeostasis will inevitably result in Type II Diabetes Mellitus. The goal of this project is to establish a model system for studying the role of CREB3 in insulin secretion of pancreatic beta cells through CRISPR-Cas9 mediated knockout and to test the role of CREB3 in insulin secretion through various treatments. The results of this study will help us to understand the mechanisms of insulin secretion and could potentially offer insight into the development of treatments for Type II Diabetes.
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    Classifying Canadian Pork Primals Based on Colour, Firmness, and Lean-fat-bone Ratio
    (University of Guelph) Wei, Xinyi; Duizer, Lisa; Manuel, Juárez; Benjamin, Bohrer; Manickavasagan, Annamalai
    The work aimed to provide innovations for categorizing Canadian pork primals, including loins, hams, and bellies, by focusing on essential quality attributes: colour, lean-to-fat ratio, and firmness, ultimately enhancing industrial processes. Study 1 compared recently developed devices to Minolta spectrophotometers for measuring colour (252 loin chops; 46 tenderloins). Newly developed instruments presented low RSD (< 5%), with minor variations in the a* values for the Nix Pro II and b* values for the Spectro 1 Pro. Correlations with subjective standards were higher for Nix and Spectro devices, compared to Minolta. Newly developed devices presented reliable pork surface colour measurement. Study 2 investigated the image analysis method to categorize pale pork loins. Colour of the ventral side (n= 550) was correlated (r= 0.79, P< 0.05) to the lean muscle area of centre chop. Thresholds at multiple levels (2.5th, 5th, and 7.5th) for the palest ventral surfaces were selected to classify centre chop. The method achieved a categorization accuracy of 87% at the 7.5th percentile of ventral sides, suggesting its potential utility for processors in the pre-sorting of commercial pork. Study 3 used image analysis on 248 bone-in hams to classify extremely fat or lean hams. Linear measurements of fat layers predicted known composition of the whole ham with R2= 0.7. A system based on these predictions aimed to classify extremely fat or lean hams at the 10th percentile threshold. Accuracy dropped by 18% for lean ham prediction but increased by 60% for fat ham prediction at the 30th percentile threshold. In Study 4, an automated conveyor system simulated the production line movement to classify 94 bellies based on firmness at 4°C, 2°C, and -1.5°C. Temperature significantly (P< 0.05) affected bending angles. Multiple bends only changed firmness classification at 4°C and 2°C. The findings from all studies contribute insights for the development of an automated classification system focusing on meat surface colour or the firmness of pork belly primals. Furthermore, the linear measurements on ham faces can be effectively utilized in the construction of a manual device designed for the classification of pork ham primals based on composition.
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    Retirement Productivity: Working, Volunteering and Caregiving in Retirement Age Baby Boomers
    (University of Guelph) Kelly, Mac Donald; Lyons, Sean
    Studies on retirement suggest a dichotomous choice that retirees are either satisfied or dissatisfied with their retirement. However, the research suggests that baby boomers experience this stage differently than their predecessors, approaching a potential 30-year retirement with better health and a new perspective on aging and retirement. Using a Life Course framework, this study looks at a more nuanced perspective that indicates a spectrum of retiree satisfaction within the baby boomer population. Using a cluster analysis and the dataset from the Canadian Longitudinal Study on Aging, this study found that baby boomers participate in nine unique combinations of activities in retirement and that these combinations of working, caregiving and volunteering resulted in varying outcomes for health and happiness as measured by satisfaction with life, healthy aging, general physical health, general mental health, social engagement, subjective social status, financial sufficiency and financial future. In recognizing the contribution that retirement age Canadians make, this study introduced the idea of ‘retirement productivity’ to the lexicon on retirement research, encompassing the various permutations of paid and unpaid work in retirement. The results showed that with three exceptions, those who are retired are generally happier and healthier than those who are retired are generally happier than those who are not retired and working but that it depended on retirement productivity. This study looked at the possible reasons for this spectrum of satisfaction in retirement. It concluded that retirees are a heterogenous group and what they do during their retirement years is associated with their levels of health and happiness in this third stage.