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- ItemMetal-ligand cooperation in bis(phosphinimine)-supported rhodium pincer complexes: from dehydrogenation to value-added products(Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2025) Hsiang, Shou-Jen (Edward); University of Lethbridge. Faculty of Arts and Science; Hayes, Paul G.Expansion of methodology towards the synthesis of pincer ligand (L = κ3-NNN’ = 2,5-[iPr2P=N(4-iPrC6H4)]2-N’(C4H2)-) supported rhodium tetrylene (κ2-L(CO)Rh(ER2); E = Si, Ge; κ2-L = κ2-NN’-Rh, κ1-N-E) and borylene (κ2-L(CO)Rh(BMes); Mes = mesityl) species is described, followed by investigations into the reactivity of these new complexes. A metal-ligand cooperative approach was used to dehydrogenate group 14 starting materials of the form RR’EH2 (E = Si, Ge; R = aryl or alkyl; R’ = H, aryl or alkyl) and MesBH2 (Mes = mesityl), and the resulting complexes were characterized by a variety of instrumentational techniques (NMR, IR, EA). X-ray crystallography was used to unambiguously confirm the solid-state structure within these species, establishing the hemilability of the R3P=NAr “phosphinimine” nitrogen-donor of the pincer ligand as well as its base-stabilization capabilities. Diverse reaction chemistry was demonstrated for these species, starting with dehydrocoupling reactions with pinacol, which provided proof that the activated main group functionalities could be used as {BMes}, {SiRR’}, and {GeRR’} synthons and transferred to organic substrates. Additionally, reaction of a base-stabilized borylene complex with a variety of alkynes and CO gas yielded highly functionalized boron-containing heterocycles ((PhC=CRBMesO)C=NPipp) that would be difficult to synthesize by alternative routes, showcasing the potential these systems have for applications. Finally, the H-substituted silylene complex, κ2-L(CO)Rh(Si(H)Mes), was demonstrated to react with tris(pentafluorophenyl)borane to yield an elusive silylyne complex, the first of its kind with rhodium. Altogether, a cohesive body of work encompassing the development of new methodologies, diverse reaction chemistry, and the presentation of future areas for pursuit are described herein.
- ItemEntomopathogenic fungi: an alternative for the biological control of aphids (Phorodon cannabis) in cannabis (Cannabis sativa) plants(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Lopez Restrepo, Daniel A>; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, IgorThe rapid expansion of the cannabis industry in Canada post-legalization has heightened the prevalence of pests, particularly the cannabis aphid Phorodon cannabis,which poses significant threats to crop health. This study investigates the immediate effects of P. cannabis on Cannabis sativa plants and explores biological control strategies utilizing entomopathogenic fungi. The research aims to test the antagonistic activity of various fungal isolates against aphids, analyze the immune responses of cannabis plants to infection, assess the impact on metabolite production and yield, and develop effective application strategies for these biocontrol agents. Fungal isolates of Beauveria and Metarhizium were isolated and characterized. Infection tests on aphids demonstrated the potential of these fungi to control aphid populations without the environmental drawbacks associated with chemical insecticides. Bioassays revealed that both fungi achieved 100% aphid mortality at high conidial concentrations (1×10⁷ conidia/mL), with Beauveria bassiana demonstrating faster efficacy. In greenhouse trials, Beauveria bassiana maintained aphid populations below 20 aphids throughout the experiment across all varieties and maintaining cannabis growth parameters comparable to the chemical insecticide. Untreated aphid infections substantially reduced plant height and biomass across three cannabis varieties tested, reaching heights of 40-48 cm and under 4 g of dry biomass. Cannabinoid and terpene analyses revealed that Beauveria bassiana-treated plants exhibited higher concentrations of key metabolites, including THCa, CBDa, and total terpenes, compared to chemically treated plants. The findings highlight Beauveria bassiana as an eco-friendly alternative for pest management that not only effectively controls aphids but also supports the biochemical quality of cannabis plants. Findings suggest that entomopathogenic microorganisms can significantly mitigate the impact of P. cannabis on cannabis seedlings, offering a sustainable alternative to chemical controls. This research contributes to the understanding aphid interactions with cannabis plants and promotes eco-friendly pest management practices within the burgeoning cannabis industry.
- ItemApplication of antimicrobial peptides to control leaf rust (Puccinia triticina) infection in bread wheat (Triticum aestivum L.)(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Panthi, Urbashi; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, Igor; Bilichak, AndriyScreening and developing novel antifungal agents with minimal environmental impact are needed to maintain and increase crop production constantly threatened by various pathogens. Small peptides with antimicrobial and antifungal activities have been known to play an important role in plant defense both at the pathogen level by suppressing its growth and proliferation as well as at the host’s level through activation or priming of the plant’s immune system for faster, more robust response against fungi. Rust fungi (Pucciniales) are plant pathogens that can infect key crops, threaten global food security and are capable of overcoming the resistance genes introduced in elite wheat cultivars. We performed an in vitro screening of 19 peptides predominantly of plant origin with antifungal or antimicrobial activity for their ability to inhibit leaf rust (Puccinia triticina, CCDS isolate) urediniospores germination. Nine peptides demonstrated significant fungicidal properties compared to the control. Foliar application of the top three candidates, β-purothionin, Purothionin-α2 and Defensin-2, decreased the severity of the leaf rust infection in wheat (Triticum aestivum L.) seedlings. Additionally, increased pathogen resistance was paralleled by elevated expression of the defense-related genes.
- ItemMultigenerational UV stress effects in Arabidopsis thaliana offspring(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Lopez Virgen, Andres Guadalupe; University of Lethbridge. Faculty of Arts and Science; Kovalchuk, IgorContinuous exposure to environmental stress contributes to species diversity and drives microevolutionary processes. However, whether epigenetic alterations, such as differential DNA methylation, are prerequisites for speciation events remains unclear. We hypothesized that prolonged stress exposure would increase epigenetic diversity more than genetic diversity. In this study, we analysed the effects of 25 consecutive generations of UV-C stress on the genome and epigenome of Arabidopsis thaliana. Our results showed that multigenerational UV-C exposure led to significant genetic and epigenetic changes in the progeny. Genomic analysis of the UV-stressed progeny (F25UV) revealed a higher frequency of genetic variations compared to controls (F25C, F2C), with deletions being more prevalent than insertions, probably due to the mechanisms of DNA damage and repair processes triggered by UV radiation. F25UV also exhibited a significantly higher proportion of nonsense mutations, with C-to-T transitions being the most common, likely due to deamination of methylated cytosines. Epigenomic analysis showed that F25UV plants had more differentially methylated cytosines (DMCs) across all contexts than the F2C group. F25UV also had more DMCs than the F25C group in the CHG and CHH contexts, with the most striking difference in the CHH context, where F25UV had over 10-fold more DMCs than the F25C group. Despite these genetic and epigenetic changes, no differences in progeny resilience under stress were observed, based on root analysis, reactive oxygen species levels, and overall growth at both the seedling and mature stages. Our findings suggest that UV radiation stress can induce genetic and epigenetic changes that are capable of being inherited in transgenerational manner. Although these changes did not result in more resilient plants, their non-random nature suggests an evolutionary and adaptive direction.
- ItemIndigenous anarchism: a story of resistance, reconcilliation and becoming through the decolonization of ways of knowing(Lethbridge, Alta. : University of Lethbridge, Dept. of Sociology, 2024) Fox-Grey, Elizabeth K.; University of Lethbridge. Faculty of Arts and Science; Hogue, Michelle M.; Ramp, WilliamABSTRACT The purpose of this thesis is to examine some aspects of what is needed to work reconciliation (healing) into western academic institutions via the art of resistance and the decolonization of methodologies in social science. The decolonization of methodologies will entail freedom to engage in a rigorous effort to engage with Indigenous ontologies and epistemology, and Indigenous selfhood and the spirit, as well as recovering and extending particular Indigenous knowledge systems. The decolonization of methodologies will foster not only better research but also the autonomy of Indigenous graduate students and their agency to embrace their cultural, landed and ancestral selves. Decolonization of methodologies could be a sign of the seriousness of commitment by Canadian universities to reconciliation. Indigenous students need to be able to feel at home on the territory where universities are located – their territories. Decolonization of methodologies will reconcile the precolonial past and the still-colonized present colonization by helping to remove the hegemonic claims of the European Enlightenment to govern all knowledge production. I hope to have demonstrated how I see Michelle Hogue, Kori Czuy, Casey Eagle Speaker, Robin Wall Kimmerer and others as having fostered, in their different ways, new approaches to Indigenous theory and/or research. I take a decolonizing approach to western epistemology, ontology and methods to highlight the way that Indigenous ontology and epistemology can add value to the future of research and scholarship.