Theses and Dissertations at Montana State University (MSU)
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/732
Browse
8 results
Search Results
Item Colloids, diagnostics, and 3D-printed hydrogels(Montana State University - Bozeman, College of Engineering, 2021) LeFevre, Thomas Brian; Chairperson, Graduate Committee: James Wilking; This is a manuscript style paper that includes co-authored chapters.Colloidal suspensions are dispersions of microscopic particles in liquid. Their properties have broad impacts in industry, medicine, and biology. In Chapter 2, we focus on measuring the interactions between colloidal particles suspended in water and a glass surface. We measure these interactions using a custom-built fluorescence centrifuge force microscope (F-CFM). This is the first CFM built with fluorescence capability, the first CFM used to measure colloidal interaction forces, and the first CFM capable of operating at speeds above 2000 RPM - and up to 5000 RPM - in a centrifuge. The F-CFM enables colloidal scale objects to be discriminated by fluorescence, which opens potential applications for biological samples that fluoresce under different phenotypic states. In Chapter 3, we focus on designing a point-of-care (POC) saliva collection, metering, and mixing system for detecting viral pathogens. The device was designed for the specific purpose of testing for the presence of SARS-CoV-2 in saliva using molecular amplification methods but could be applied to any pathogen whose constituents can be detected in saliva. The design to prioritizes ease of use, low cost, and scalability in order to facilitate massively widespread testing, which was absent during the first years since the emergence of SARS-CoV-2, In Chapter 4, we describe a method of formulating and printing hydrogel resins with high resolution channels using light-based 3D printing. In Chapter 5, we describe a leak-resistant, pressurized connector platform for connecting modular hydrogels that can be used to create complex assemblies of hydrogel components. In Chapter 6, we describe a microscope sample temperature control platform that fits into standard upright microscope stages in order to heat and cool samples in a controlled manner under the microscope in order to observe temperature dependent reactions like polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). In Chapter 7, we describe a LAMP formulation that can be used to detect the presence of SARS-CoV-2 RNA in saliva despite the inhibitory components present in saliva and demonstrate its comparable accuracy to the gold standard of pathogenic testing: nasopharyngeal PCR testing.Item Evaluating the effects of climate change and pathogens on pollinator health using plant functional traits and longitudinal monitoring(Montana State University - Bozeman, College of Letters & Science, 2017) Glenny, William Robb; Chairperson, Graduate Committee: Laura Burkle; Michelle Flenniken (co-chair)Pollinators are essential for the maintenance of biodiversity, ecosystem function, and economic productivity. In particular, bee pollinators are required for plant reproduction and pollination of agricultural crops. However, land use change, climate change, pathogens, pesticide exposure, among other factors likely act alone and in combination to negatively impact bee pollinators and the services they provide. Further resolution of the effects of these stressors, both individually and combined, on bee pollinators is important to understand the global decline of pollinator health. Abiotic conditions associated with climate change may alter plant traits important for pollinator attraction leading to in shifts in plant-pollinator communities. Floral visual and chemical traits were measured in four species of forbs subjected to elevated or ambient concentrations of carbon dioxide, and decreased or normal water availability in a fully factorial crossed design. Treated plants were observed for pollinator visitation rates and community composition to better understand the mechanisms by which climate change can influence pollinator attraction. Results indicate that changes in both visual and chemical cues of plants will alter plant-pollinator interactions. Furthermore, plant functional trait responses to climate change increase competition for pollinators in forbs with overlapping flower types, while facilitating pollinator visitation to forbs with dissimilar flower types. Pathogens contribute to annual honey bee colony losses and the declining populations of some wild bee species. Bee pathogens, including viruses, fungi, microparasites and ectoparasites, can vary across geographic location and season. To examine the impact of pathogens on honey bee colony health, using colony size as a proxy for health, we longitudinally monitored pathogen prevalence and abundance of pathogens in honey bee colonies involved in California almond pollination. Individual honey bee associated pathogens varied throughout the one year monitoring period, but Deformed wing virus in parallel with increasing levels of Varroa destructor mite infestation predominated shifts in honey bee pathogen profiles by the end of the sampling period. Our results indicate that bee populations experience multiple concurrent threats operating at multiple scales to affect pollinator health. Continued investigation into factors affecting pollinator health both independently and in concert are needed to develop strategies mitigating declines in pollination services.Item Potato and potato virus Y: the effect of cultivar, seed type, and dfense-inducing agents differences in incidence(Montana State University - Bozeman, College of Agriculture, 2016) Boyd, Elisa Kirk; Chairperson, Graduate Committee: Michelle Flenniken; Eileen Carpenter, Michelle Flenniken and Nina Zidack were co-authors of the article, 'Potato cultivar and seed type affect incidence of potato virus Y (PVY N-WI) infection' submitted to the journal 'Plant disease' which is contained within this thesis.; Eileen Carpenter, Michelle L. Flenniken and Nina Zidack were co-authors of the article, 'Examination of resistance-inducing compounds to limit potato virus Y (PVY N-WI) infection in potatoes' which is contained within this thesis.Potato (Solanum tuberosum subsp. tuberosum) is an important crop grown worldwide. Propagated vegetatively, a sustainable potato industry relies on pathogen free, tissue culture-produced plantlets to maintain low disease incidence in seed potato stock. Potato virus Y (PVY) infection is the most significant threat to seed potato production. Therefore, determining the influence of cultivar and seed type on PVY incidence could lead to improved management practices. Data from seed potato certification inspection in Montana indicated that plants grown from seed produced in sterile conditions (plantlets and minitubers) had a greater incidence of PVY than plants grown from field-produced tubers. We hypothesized that differences in cultivar, seed type and growth conditions (i.e., sterile vs. field grown) impacted PVY incidence. Systemic acquired resistance (SAR) is a plant immune response that is induced by pathogens and resistance-inducing agents. Resistance-inducing agents are effectively used to limit fungal pathogens, and we hypothesized that they may also limit PVY infection. To test these factors, potato plants (cultivars Russet Burbank and Norkotah Colorado 3) were grown from multiple seed types (i.e., plantlet, minituber, and Generation 3 tuber (G3)) and mechanically inoculated with PVY strain Wilga in the presence and absence of Systemic Acquired Resistance (SAR) inducing agents. Percent infection (incidence) was measured with double-antibody sandwich enzyme-linked immunosorbent assay (DASELISA) at three time points post-inoculation. These studies resulted in the following conclusions: (1) incidence of PVY infection varies by cultivar, specifically, the Russet Burbank cultivar had a lower incidence of PVY than the Norkotah Colorado 3 cultivar, (2) Russet Burbank plants grown from tissue culture plantlets had a higher incidence of PVY infection than Russet Burbank plants grown from field-produced G3) tubers, and (3) phosphorous acid (Phostrol®), an inducer of Systemic Acquired Resistance (SAR) may reduce PVY infection, particularly in Russet Burbank plantlets. These findings advance our understanding of the differences in PVY incidence by cultivar and seed type, and in turn provide valuable information for maintaining pathogen free potato seed.Item Population dynamics of coexistence by plant pathogens of the rhizosphere of spring wheat(Montana State University - Bozeman, College of Agriculture, 2015) Troth, Erin Elizabeth Gunnink; Chairperson, Graduate Committee: Alan T. DyerThe dryland root rot complex is a collection of root pathogens that significantly affect small grain production in the semiarid regions world-wide. The complex includes Cochliobolus sativus, Fusarium pseudograminearum, Rhizoctonia solani, Pythium ultimum, and Penicillium sp. The purpose of this thesis was to document the interactions among these pathogens that commonly coexist within the wheat rhizosphere. The thesis had two objectives: 1) examine variation in interactions amongst isolates of C. sativus and F. pseudograminearum within the wheat crown and 2) identify interactions among pathogens in the dryland root rot complex (C. sativus, F. pseudograminearum, R. solani, P. ultimum, and Penicillium sp.) in-field, as reflected in plant response variables. For objective 1, wheat in both field and greenhouse settings were inoculated singly and in all pathogen isolate combinations. Both C. sativus and F. pseudograminearum, alone and in combination, reduced yield (P<0.001, P=0.003, respectively), but C. sativus isolates had a greater effect on both yield and emergence (P<0.001). Inoculations with some isolates of C. sativus and F. pseudograminearum were suppressive on populations of each other. Significant variability in suppressiveness was observed among isolates for both species. For objective 2) plant health as measured by emergence, vigor, plant height and yield, was observed in response to inoculations with all single, pairwise, four-pathogen and five-pathogen combinations of C. sativus, F. pseudograminearum, R. solani, P. ultimum, and Penicillium sp. Antagonistic relationships that favored overall plant health were observed between several pathogens, including P. ultimum, Penicillium sp. and C. sativus. These antagonistic interactions affected seedling emergence and plant vigor. Conversely, F. pseudograminearum in combination with R. solani significantly reduced emergence beyond expected (P=0.002). Within the community interaction studies overall, F. pseudograminearum was the dominant pathogen, causing more disease and more consistent disease than any other pathogen, and generating increased damage to emergence when inoculated in the community (P=0.017). In conclusion, interactions among members of the dryland root rot complex is a dynamic process, one that varies by species and pathogen isolate. These interactions are more often antagonistic, with one pathogen suppressing another. Additional studies may improve how disease control measures are deployed in the future.Item The millipede of Santo Antao, Spinotarsus caboverdus : survey for pathogenic microorganisms, bioassay tests of fungal pathogens against S. caboverdus and Melanoplus sanguinipes(Montana State University - Bozeman, College of Agriculture, 1994) Brito, Jorge MendesItem Pathogenicity of Vairimorpha sp. (Nosematidae: Microsporida) in the Mormon cricket, Anabrus simplex (Tettigoniidae: Orthoptera)(Montana State University - Bozeman, College of Agriculture, 1991) Currey, David MichaelItem Vertical transmission of a dimorphic microsporidium (Microspora) in the Mormon cricket, Anabrus simplex (Orthoptera: Tettigoniidae)(Montana State University - Bozeman, College of Agriculture, 1993) Djibode, FrancoiseItem A comparative study of enterotoxic and non-enterotoxic micrococci(Montana State University - Bozeman, College of Agriculture, 1949) Morledge, David R.