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- ItemTrait aggression and its impact on memory for violent information(Lethbridge, Alta. : University of Lethbridge, Dept. of Psychology, 2025) Reinink, Michelle R.; University of Lethbridge. Faculty of Arts and Science; Mansour, JamalI investigated whether an individual difference, specifically trait aggression, affects how violent information is remembered. My main hypothesis was that participants with higher trait aggression would better remember details of violence and be more accurate in identifying the perpetrators of violent actions than those with lower scores, while memory for non-violent events would not differ based on trait aggression. To test this, I used an eyewitness memory paradigm wherein participants watched a violent or non-violent video and indicated how aggressive they perceived the content and the person who committed the violent/non-violent act to be. Memory for the videos was measured with recall and recognition questions for the people in the videos. During the delay between the video and the lineups, participants completed the Buss-Perry Aggression Questionnaire (Buss & Perry, 1992). Next, participants completed a target-present or target-absent lineup for each of the two individuals from the video. Contrary to my hypothesis, increased trait aggression was not associated with increased memory for violent events, though it was associated with biased perceptions. Participants high in trait aggression perceived more aggression in non-violent videos and less aggression in violent ones than participants low in trait aggression. An implication of this research is that if an eyewitness perceives relatively neutral information as aggressive, this could affect how administrators of justice perceive the suspect, in turn potentially affecting investigations and subsequent sentencing.
- ItemBiophysical characterization of Zika virus terminal region interactions(Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2025) Kerr, Liam A.; University of Lethbridge. Faculty of Arts and Science; Patel, Trushar R.Recent viral threats have intensified research into viral mechanisms and the various interactions during their viral life cycle. Viruses such as Zika virus have continued to threaten healthcare systems around the globe, with large outbreaks affecting over 3 million people within the last decade. While viral proteins have received significant attention, the untranslated terminal regions (TRs) flanking the single-stranded RNA genome play crucial roles in the viral life cycle. These TRs facilitate replication through interactions with host/viral proteins and through self-association via cyclization, which regulates transcription and translation. This thesis characterizes the biophysical and cellular properties of this cyclization interaction and the TRs interaction with the host protein FXR1. Using size exclusion multi-angle light scattering and analytical ultracentrifugation, we defined the hydrodynamic profiles of the TRs and FXR1. Microscale thermophoresis quantified the affinity and specificity of the TRs cyclization interaction, as well as the affinity of FXR1 for the TRs. Cellular studies further demonstrated that TR mutations disrupting cyclization drastically reduce viral replication. Collectively, this work identifies a sequence specific interaction governing Zika virus replication and establishes a foundation for characterizing the TR-FXR1 interaction, offering potential targets for future therapeutic development.
- ItemThe impact of mRNA modifications on ribosomal decoding: a molecular dynamics simulation study(Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2025) Lea, Mark J.; University of Lethbridge. Faculty of Arts and Science; Wetmore, Stacey D.Post-transcriptional RNA modifications are key regulators of translational accuracy and efficiency. While ribosomal RNA (rRNA) and transfer RNA (tRNA) modifications have well-characterized roles in protein synthesis, the functions of messenger RNA (mRNA) codon modifications are less understood. However, growing evidence suggests that mRNA codon modifications can modulate translation. Naturally occurring mRNA modifications can be enzymatically added, such as inosine (I), which is incorporated into mRNA codons to expand decoding capacity and remodel the proteome. Alternatively, modifications can result from damage to mRNA codons, such as the alkylative lesions 1-methylguanosine (m1G) and 2-methylguanosine (m2G), which can have potentially unpredictable and harmful consequences. This thesis developed a large-scale computational model of the ribosomal A-site (>370,000 atoms) and performed molecular dynamics (MD) simulations to understand the position-dependent structural effects of the inosine, m1G, and m2G codon modifications. These investigations revealed that modified codons associated with experimentally-observed reduced peptide formation rates exhibit tRNA dissociation or distorted decoding center geometries. In contrast, modified codons with negligible effects on experimental rates maintain A-site conformations that promote productive decoding. Thus, this thesis provides mechanistic insight into how mRNA modifications can regulate translation at the atomic level and establishes a robust computational method for future studies that strive to understand the roles of numerous additional RNA modifications during translation.
- ItemEvaluating wetland extent trends using remote sensing: case studies in the Canadian Rockies(Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment, 2025) Rodrigues, Italo Sampaio; University of Lethbridge. Faculty of Arts and Science; Hopkinson, ChristopherMountainous wetlands provide critical ecosystem services, but their sustainability is increasingly threatened by climate change impacts on river flow, runoff regimes, and landscape dynamics. The main objective of this thesis is to investigate how wetland hydrology and land cover in two mountainous regions, the Upper Columbia floodplain in British Columbia and the Eastern Slopes of Alberta (ES), are changing over time and how they could react under future climate scenarios. The specific aims of this thesis are to: 1) Evaluate historical and projected changes in wetland land cover and hydrology in the Upper Columbia River floodplain (1984–2040); 2) Apply and expand these methods to the ES (1984–2023); 3) Quantify open water evaporation relative to forest ecosystem evapotranspiration volumes, and assess seasonal variations between the snowmelt- and rainfall-dominated periods. Results on Objective 1 indicate that from 1984 to 2022 the Upper Columbia floodplain has already undergone significant hydrological and ecological changes. Peak river discharge now occurs eleven days earlier and with shorter duration, so generating greater peak flows over a shorter period. These shifts have matched a drying trend in wetland habitats and a transition to woody and shrubby vegetation. Under both RCP 4.5 and RCP 8.5, projected data (2020s–2040s) show a continuous reduction in late-summer open water areas; the seasonal peak shifts earlier into spring (April to mid-May). Applying a similar analytical approach to the ES in Objective 2 revealed both parallel and contrasting trends. In the snowmelt-dominated period (late May to mid-July), subalpine (≤2300 m) and alpine (>2300 m) regions experienced increases in open water, non-woody, and woody/shrub vegetation while barren land decreased. On the other hand, the rainfall-dominated period (late July to mid-September) revealed a decline in open water area and an increase in barren land, so suggesting possible seasonal water constraints and vegetation changes. For Objective 3, the estimated proportion (P%) of open water evaporation in relation to volumes of forest ecosystem evapotranspiration. Historically, P% was 2.4% during the snowmelt-dominated period and 2.1% during the rainfall-dominated period. Especially in earlier stages of the hydrologic year, these trends indicate rising contributions of surface water bodies to total evapotranspiration. The consequences comprise changed water availability, habitat changes, and the long-term viability of wetland ecosystem services. The noted seasonality of hydrological changes and acceleration highlights the need for adaptive water management and conservation strategies considering local and regional dynamics.
- ItemAltered behaviour and transmission ecology of fluke-infected zombie ants(Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, 2025) Edison, Lauren M.; University of Lethbridge. Faculty of Arts and Science; Goater, Cameron P.Parasites can induce changes in the colour, morphology, and behaviour of their hosts. In some cases, the induced changes are extraordinary in their expression. In an iconic example, Formicid ants infected with the lancet liver fluke, Dicrocoelium dendriticum, attach their mandibles to a plant for hours or days. I described patterns of infection in two species of ants infected with D. dendriticum in a region of parasite emergence in southern Alberta and found that ants recruit parasites in clumps from their first intermediate host, terrestrial snails. Overall, infected ants contain, on average 27±25 (mean ± standard deviation) encysted metacercariae (n = 677). In a departure from classic examples of parasite manipulation, infected ants do not die on the plant. Rather, they detach, resume normal ant activities, then re-attach. This bizarre ‘attach/detach/repeat’ sequence of altered behaviour likely facilitates transmission into grazing mammals while also preventing desiccation of the ant hosts and their parasites. I conducted a field study monitoring the behaviour of infected ants and found that the timing of attachment and detachment of ants on plants is closely linked with environmental factors such as light intensity, relative humidity, temperature, and also with ant circadian rhythm. Additionally, I completed a spatiotemporal analysis of the distribution of infected ants on plants in the field and found that infected ants are often aggregated on plants adjacent to the nest that they originated from, representing the first reported case of “super aggregation” of parasites. Whereas a pattern of strong aggregation on plants was spatially and temporally consistent for one species of Formicid ant in this region of parasite emergence, the behavioural processes leading to aggregation are enigmatic, as are the consequences of aggregation for rates of fluke transmission from ants into definitive hosts.