Arts and Science, Faculty of
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- ItemThe impacts of circadian disruption on hippocampal place cell activity(Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience, 2024) Robertson, David R.; University of Lethbridge. Faculty of Arts and Science; McDonald, RobertCircadian rhythms are daily physiological cycles with wide-reaching influence on biological, mental and behavioural functions. We are at our best when our circadian rhythms function in a stable and consistent manner synchronous with stable and consistent patterns of day and night. Disruptions to circadian rhythms cause all manner of negative effects. One effect that is of particular interest to this study is that spatial memories formed while circadian rhythms are in disarray are not retained as well as those formed in stable conditions. The sorts of memories affected this way have a common factor. They all rely heavily on the hippocampal memory system. Methods have already been devised to read and decipher the neural code of hippocampal place cell firing patterns. However, until now, no attempt has been made to view how circadian disruption influences these hippocampal neural patterns. This experiment bridges that gap.
- ItemTwo plant extracts that cause unique aggregated phenotypes in Staphylococcus aureus and could act as an antibiotic alternative(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024-05) Hand, Nadia; University of Lethbridge. Faculty of Arts and Science; Kernéis, Sophie; Golsteyn, RoyThis thesis is about the abilities of two plant extracts to cause aggregation or “clumping” of Staphylococcus aureus. This project is in response to rising levels of antibiotic-resistant bacteria, and a lack of methods to control the dispersal of bacteria of agricultural origin. As the implementation of antibiotics in the agricultural sector has increased since the discovery of antibiotics, concerns regarding human health have arisen. The use of antibiotics acts as a selection pressure against bacteria that are susceptible to the antibiotic’s effects. This allows for those bacteria that possess antibiotic resistance to reproduce, creating strains of mainly antibiotic-resistant bacteria. The purpose of this thesis is to investigate two clump-inducing plant extracts that are a potential tool to limit the dispersal of bacteria in solution (ex. Bacteria in agricultural wastewater). By promoting clumping in the bacteria, it is thought that the bacteria’s dispersal will be limited, decreasing instances of infection, thereby indirectly reducing the need for antibiotic use. The two plant extracts studied here were selected from a library of bacterial clump-inducing plant extracts. They come from different botanical families and induce clump formation in S. aureus resulting in differing clump phenotypes. In addition to clump formation, both plant extracts cause a significant reduction in the growth of S. aureus (F (3, 72) = 4.022E+17, p < 0.001), (F (3, 58) = 185, p < 0.001). It is found that clumping molecules act in an adhesive manner and that the bacteria do not play an active role in clump formation. With this finding the first steps of affinity purification of clumping molecules were carried out for further identification of their chemical identities. This thesis outlines a procedure to study, compare and purify other clump-inducing plant extracts, many of which have not been investigated.
- ItemSoil acidity in southern Canadian prairie chernozemic agricultural soils(Lethbridge, Alta. : University of Lethbridge, Department of Geography and Environment, 2024) Wagner, Mark H.; University of Lethbridge. Faculty of Arts and Science; Peddle, Derek Roland; Jensen, ThomasSoil acidity is an increasing concern for growers in the southern prairies of western Canada. This study took place over a three-year period, starting in 2020, the research lime treatment plots were established in low soil pH zones, in the three cropped fields: Hilton, Sierra and Kings Lake. Both powdered or granular lime was surface applied on long-term no-till fields, with one of three placement methods: no incorporation, incorporation with harrowing, or incorporation using tillage. Soil sampling was followed by pH measurements conducted in November 2021 and 2022. In Fall 2021 only the treatment of powdered lime incorporated using tillage increased the soil to the pH target of 6.5 for the 0-15 cm depth. By Fall 2022 soil sampling, pH analyses showed that all lime treatments were effectively ameliorating the low pH soils. Further study investigated spatial variability of soil pH on the study fields, the most practical sampling density for accurate pH maps was shown to be 1 sample spot per 0.8 hectares. After this study, data was gathered on the incorporation methods and lime forms. It was determined all treatments sufficiently raised the pH to an acceptable level for crop growth, after two years. Furthermore, the assessment on pH variability was vital to understanding how variable soil pH can be in a field.
- ItemExploring sulfate cycling in a mineral-soil wetland restored with wastewater(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Denny, Mariya; University of Lethbridge. Faculty of Arts and Science; Bogard, Matthew J.Sulfate (SO42-) pollution is contributing to the salinization of surface waters worldwide. Wetlands are natural filters on the landscape that remediate surface water by retaining and processing pollutants. However, the capacity for wetlands to process excess SO42- from wastewater is poorly understood, especially for natural (as opposed to constructed) wetlands. Here, I explore the SO42- remediation capacity of Frank Lake, a restored, multi-basin wetland complex in southern Alberta, Canada, that is used to treat effluent from municipal and beef slaughterhouse sources. Using a combination of approaches, I show that there was limited SO42- processing throughout the wetland. Mass balances constructed for two distinct hydrologic periods showed that Frank Lake shifted from a SO42- source during wet years (2013 - 2015) to a sink during drought years (2021 - 2022). Yet I found little evidence of active SO42- processing in surveys conducted during drought years. SO42- remained the dominant form of sulfur (S) among all three basins (>95% of total S), implying little net change in the S pool. Similarly, dual stable isotope ([delta]34S and [delta]18O) analysis showed limited isotopic enrichment among wetland basins, implying limited transformation of SO42- via microbial reduction. Sediment incubations confirmed the patterns observed with stable isotopes, showing little net removal of SO42- throughout the wetland. The preferential reduction of nitrate (NO3-) and other more energetically favourable constituents of the effluent may restrict the extent of microbial SO42- reduction throughout Frank Lake. The limited extent of emergent and submerged vegetation may also limit SO42- uptake by plants. Given the limited SO42- processing in Frank Lake, and the headwater position of this wetland complex in the broader aquatic network, my work provides context for previous reports of increasing salt concentrations documented in rivers of the South Saskatchewan River watershed.
- ItemInvestigating the structure-function relationship of anti-mitotic natural products in Canadian prairie plants(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2024) Healy Knibb, Shannon M.; University of Lethbridge. Faculty of Arts and Science; Golsteyn, RoyThis thesis investigates Canadian prairie plants as sources of natural product compounds capable of inhibiting human cell division. Natural products present an opportunity to identify novel anti-mitotic compounds to address the lack of known inhibitors for many mitotic regulatory proteins. By biology-guided fractionation, we purified the natural products anemonin from Pulsatilla nuttalliana and (+)-6-tuliposide A from Erythronium grandiflorum, and this is the first report of their anti-mitotic activities. We then conducted a comparative study between pulchelloid A (from Gaillardia aristata), anemonin and (+)-6-tuliposide A, and identified unique mitotic arrest profiles, suggesting distinct protein targets and mechanisms of action consistent with the widespread relationship between structure and function in biology. The discovery of natural product inhibitors from Canadian prairie plant species holds tremendous potential for advancing our understanding of mitotic regulation and contributes to the development of targeted treatments for precision medicine.