FGS - Electronic Theses and Practica

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This collection contains University of Manitoba electronic theses and practica.

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Recent Submissions

Now showing 1 - 5 of 26222
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    Open Access
    Survey and development of a molecular test for Soybean Cyst Nematode (Heterodera glycines Ichinohe) in Manitoba
    (2024-04-29) Ghavami Shirehjin, Nazanin; Zvomuya, Francis (Soil Science); Gulden, Robert (Plant Science); Tylka, Gregory (Iowa State University); Tenuta, Mario
    Soybean Cyst Nematode (SCN), Heterodera glycines (Ichinohe 1952), recognized as a major global soybean pest, is already established in the Canadian provinces of Ontario and Quebec. This study anticipated its imminent presence in Manitoba, driven by its rapid spread from U.S. counties bordering the province. The research objectives were to a) survey SCN presence in Manitoba soybean fields, b) develop a molecular method for direct soil quantification of H. glycines, and c) identify native cyst nematodes in Manitoba Prairie Preserves. The survey of 30 commercial soybean fields in Manitoba revealed four positive fields for SCN using morphological characters of cysts, PCR with species-specific primers for H. glycines (COXIII and SCAR), and DNA sequencing of four regions of the genome, marking the first report of H. glycines in Manitoba. In 2021, an additional soybean field in Manitoba showed SCN symptoms and H. glycines females on the soybean roots. A molecular test employing a SYBR Green I-based real-time qPCR assay using species-specific primers for H. glycines (COXIII and SCAR) was developed, offering a reliable, sensitive and specific means to detect and quantify H. glycines eggs directly in soil DNA extracts of Manitoba and Ontario samples. This developed method eliminates the need for labour-intensive microscopic identification and egg counting of H. glycines in soils. Soil sampling in three Prairie Preserves of Manitoba revealed that, out of the prairies sampled, only one had nematode cysts. The cysts were extracted from the rhizosphere soil of Prairie Cordgrass located in the Manitoba Tall Grass Prairie Preserve. Using morphological and molecular analysis, which involved PCR amplification and sequencing of four regions of the genome (ITS rDNA, D2-D3 expansion segments of 28S rDNA; 18S rDNA, and a fragment of Mt-DNA (COI)), the recovered cyst nematodes were confirmed to be Punctodera stonei. This finding marks the first report of P. stonei in Manitoba and only the second in Canada. The findings of this study provide valuable insights into SCN presence in Manitoba, present a reliable molecular method for H. glycines quantification in soils, and unveil the presence of a cyst nematode species in a native prairie of Manitoba.
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    Introgression of blackleg resistance genes from related Brassica species to B. napus
    (2024-04-08) Shah, Keval Pravinchandra; McCartney, Curt (Plant Science); Bandara, Nandika (Food and Human Nutritional Sciences); Chen, Guanqun (Gavin) (University of Alberta); Duncan, Robert; Stasolla, Claudio
    Canola (Brassica napus L.) is one of the most important oilseed crops, contributing more than $26 billion annually to the Canadian economy. Blackleg is caused by fungal plant pathogen Leptosphaeria maculans (Desm) Ces. et de Not. In canola, blackleg disease causes more than $1 billion in yield losses globally. There are different disease management strategies, and using resistant cultivars is one of the economically viable and environmentally sustainable approaches. There are reports of a breakdown of blackleg disease resistance in Australia, France, and Canada due to severe pathogen pressure. Twenty-two blackleg-specific resistance genes have been identified in different Brassica species. Out of these, the B-genome blackleg-specific resistance genes provide resistance throughout a plant's life. This thesis addresses the identification of putative novel sources of resistance from Brassica juncea and hexaploid Brassica into B. napus. In the first project, different B. juncea UM lines were used to identify a high level of resistance against blackleg disease and were screened with L maculans isolate 03-15-03 (AvrLm2, AvrLm3, AvrLm5-9, AvrLm6, AvrLm10, and AvrLm11) and PG4-1-M (AvrLm2, AvrLm5-9, AvrLm6, AvrLm10, and AvrLm11). Plants were inoculated with different L. maculans (AvrLm3 and avrLm3; AvrLm5 AvrLm6, AvrLm5 avrLm6, and avrLm5 avrLm6) isolates to identify the novel source of resistance in Brassica napus Westar x Brassica juncea UM3073 (UMBJ16) genotypes. For genotyping, UMBJ16 genotypes were tested for all the available blackleg-specific resistance gene-linked Kompetitive Allele-Specific PCR (KASP) (Rlm1, Rlm2, Rlm3, Rlm4, Rlm7, Rlm9, LepR1, LepR2, LepR3, and LepR4) and Simple Sequence Repeats (SSR) markers (Rlm6 and rjlm2). In the second project, the B-genome blackleg-specific resistance genes were introgressed from hexaploid Brassica into B. napus. Similar phenotyping and genotyping approaches were followed to identify the putative novel source of resistance against L. maculans isolate 03-15-03 and PG4-1-M in Brassica napus Westar x hexaploid Brassica crosses (BNHB16). This resulted in the identification of a putative novel source of resistance against L. maculans isolate PG4-1-M in UMBJ16 and BNHB16 genotypes. This newly developed germplasm will help to develop blackleg-resistant breeding material in canola and rapeseed breeding programs.
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    Role of the thioredoxin system in chronic corticosterone treatment- impaired neuronal differentiation and degeneration
    (2024-05-14) Llanes Cuesta, Maria Alejandra; Miller, Donald (Pharmacology and Therapeutics); Siddiqui, Tabrez (Physiology and Pathophysiology); Andreazza, Ana (University of Toronto); Wang, Jun-Feng
    During the stress response, the hypothalamic-pituitary-adrenal (HPA) axis releases glucocorticoids into the bloodstream, targeting different organs including the brain. Chronic stress is a major risk factor for depression. Thioredoxin (Trx) is an oxidoreductase that reverses protein cysteine thiol oxidation, inhibits apoptosis signal-regulating kinase 1 (ASK1) and has been shown to promote cAMP response element-binding protein (CREB) activation. Trx reductase (TrxR) maintains Trx in a reduced state, while Trx interacting protein (Txnip) acts as an endogenous Trx inhibitor. Studies from our lab showed that chronic stress and chronic corticosterone (CORT) treatment upregulated Txnip and induced oxidative damage in cultured mouse neurons and mouse brain, suggesting that Trx system mediates CORT-induced neuronal damage. The objective of this work is to investigate the role of Trx system in chronic CORT-impaired neuronal differentiation and CORT-enhanced neurodegeneration. First, we found that Trx and TrxR protein levels increased during differentiation, while Txnip increased during neurodegeneration of primary mouse cortical neurons. Blocking Trx with CRISPR/Cas9 or the Trx inhibitor PX12 reduced neurite outgrowth. PX12 treatment also reduced the expression of synaptic proteins vGLUT1 and PSD95. Second, we found that CREB phosphorylation increased during neuronal differentiation and that blocking Trx reduced CREB phosphorylation in primary cortical neurons. In SH-SY5Y cells, we found that H2O2 reduced CREB phosphorylation and promoted CREB cysteine oxidation, while treatment with Trx mimetic peptide CB3 reversed H2O2 effect. We also found in primary mouse cortical neurons that ASK1 phosphorylation was increased during neurodegeneration and that PX12 increased ASK1 phosphorylation. Third, we found that CORT treatment elevated Txnip protein levels, reduced CREB phosphorylation, enhanced ASK1 phosphorylation, and impaired neurite outgrowth in primary neurons. Knocking down Txnip prevented CORT-impaired neurite outgrowth. Fourth, we found that chronic CORT injections induced depressive-like behaviors in mice, which was reversed by knocking down Txnip in the frontal cortex. Our findings suggest that Trx can facilitate neuronal differentiation by preserving the cellular redox balance, inhibiting CREB cysteine oxidation and maintaining CREB activation. Trx can also inhibit ASK1 apoptotic signaling and produce a neuroprotective effect. Chronic CORT treatment can upregulate Txnip, which may further inhibit Trx activity, inhibiting neurite outgrowth and promoting depressive-like behaviors in mice.
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    Open Access
    Musicking for social change: music educators' perceptions of social justice education
    (2024-05-15) Fraser, Justin D.; Moore, Shannon (Curriculum, Teaching, and Learning); Curnow, Joe (Educational Administration, Foundations, and Psychology); Peters, Beryl
    Social justice education (SJE) is broadly understood as the pedagogical work of challenging the systems, structures, and discourses that oppress, exploit, and exclude. Importantly, SJE vis-à-vis music education offers students unique opportunities to critically connect with and respond to the world by engaging musically with issues of (in)equity and (in)justice. However, despite its transformative potential, there is limited research on how the concept of SJE is perceived by secondary music educators. This matters because music educators’ perceptions of SJE inevitably shape their orientations toward and relationships with students, pedagogy, music, and social justice. Therefore, grounded in a bricolage approach to methodology that draws on critical, poststructural, and anti-colonial perspectives, this qualitative research study employs semi-structured interviews to critically examine how 10 Grade 7 to 12 Manitoba school music educators: (a) conceptualize SJE, (b) understand the importance of SJE in relation to their roles as music educators, and (c) understand the connections between social justice, music education, and the Manitoba music curriculum framework. This study reveals that research participants’ perceptions of SJE are both constructed within and constrained by the dominant discourses of the Western classical ensemble paradigm, thereby perpetuating the hegemony of Western art music and colonial musical epistemologies while simultaneously marginalizing the work of social justice. Findings also reveal that study participants’ perceptions of SJE are largely informed by liberal conceptions of social justice which have the potential to invisibilize unequal power relations and normalize coloniality. This study is significant in coming to know how, despite music educators’ best intentions, efforts to enact social change through music education may inadvertently embody oppressive potential.
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    Open Access
    Field, textural, and geochronological investigations into the intrusion dynamics and crystallization histories of the Separation Rapids rare-metal pegmatites, northwestern Ontario
    (2024-04-16) Ching, John Garnet; Böhm, Christian (Earth Sciences); Bethune, Kathryn (University of Regina); Camacho, Alfredo; Anderson, Scott
    The Separation Lake greenstone belt (SLgb) is host to a suite of potentially economic Neoarchean Lithium – Cesium – Tantalum (LCT) complex type, petalite subtype granitic pegmatites (Big Whopper, Big Mack, Snowbank, Glitter and Marko’s). Field observations on these pegmatites such as well-developed layering, ptygmatic folds, boudins, and mullions have in the past led investigators to infer that the pegmatites experienced pervasive high-strain deformation after emplacement. In this study, we reinterpret the field relations between the pegmatites and country rock, incorporate pegmatite microtextures, and date, by the U-Pb method, the time of crystallization to reassess the role of regional-scale deformation in the distribution and morphology of these pegmatites. Uranium-Pb ratios in monazite and titanite were measured, in-situ, by LA-ICP-MS to establish the timing of regional metamorphism and pegmatite intrusion. Monazite in the country rock yields the same age, within error, of the ca. 2650 Ma Separation Rapids pluton and suggests intrusion and metamorphism were coeval in the area. The range of monazite U-Pb ages of ca. 2637 Ma, ca. 2617 Ma, and ca. 2602 Ma indicate that the pegmatites crystallized after metamorphism / deformation and may not be related to one magmatic event. Field relationships and microtextural data indicate that deformation is induced locally (i.e., not regional) and results from emplacement mechanisms during pegmatite intrusion. The dominant fabric in the country rock is defined by the alignment of hornblende and is cut by the pegmatite. Moreover, all pegmatites have a metasomatic halo of biotite that overprints the S2 fabric in the country rock. Essentially, the pegmatites acted as viscous indenters into fluidized, weakened, ductile country rock. Recognizing the fact that deformation is not a result of regional-scale deformation has important implications for exploration including: 1) pegmatites need not intrude along structural corridors, 2) the dominant direction of propagation is now oriented subvertical with the surface expression of several pegmatites suggesting the bulk of the intrusions lies buried under the current erosional surface; and 3) undiscovered LCT pegmatites may lie within other segments of metavolcanic rocks along the English River – Winnipeg River subprovincial boundary, as similar emplacement ages across the SLgb and Bird River belt of eastern Manitoba (e.g. Big Mack at ca. 2637 Ma and Tanco at ca. 2640 Ma) may infer continuous mineralization along the boundary.