2025 MU Theses - Freely available online

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    Understanding perceptions of rural tourism : a case study of the Rock Island Trail
    (University of Missouri--Columbia, 2025) Cunningham, Joseph Peter; Wilhelm Stanis, Sonja; Xu, Shuangyu
    The Rock Island Trail is one of Missouri’s newest state parks; a rail trail that will stretch nearly 200 miles across the state when it is completed. Despite the designation, a large majority of the trail is under development. Disagreement on state funding has caused a delay in the development process, leaving much of the funding and development to individual communities along the trail. Differences in speed of development have confused RIT developers, creating both a need and an opportunity to examine potential causes. Perceived benefits and concerns, planning and development, sense of belonging, and social capital were identified as possible dimensions. Residents in 19 communities along the developing section of the trail were sent postcards with a link to an online survey. Altogether, 195 valid surveys were collected, and a series of ANCOVAs were conducted. Respondents saw more potential benefits than concerns happening to their community, with a moderate sense of readiness regarding the trail planning and development, and a sense of belonging. Results were mixed with regards to social capital. While there was no significant difference between communities in differing stages of trail development, significant differences were found in trail support and prior rail trail experience, via the Katy Trail. Findings from this study can be used locally with Rock Island Trail developers and can be applied to future rail trail developments.
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    Design and evaluation of EV charging networks : a case study of the SF--LA corridor
    (University of Missouri--Columbia, 2025) El-Rjoob, Sora; Rajendran, Suchithra
    The growing adoption of electric vehicles (EVs) presents both opportunities and challenges for transportation systems, particularly in high-volume corridors. Although EVs provide environmental and economic benefits, inadequate charging station capacity can lead to congestion, long waiting times, and grid strain. This study employs a simulation-based model to evaluate EV network performance along the San Francisco--Los Angeles corridor, utilizing real-world arrival rates, behavioral factors, and grid constraints. The model implements a non-stationary M(t)/M/c simulation approach in Python to estimate and compare waiting times, booth requirements, and related costs across several scenarios under demand uncertainty, driver behaviors, and grid constraints. The simulation results show how booth allocation and system performance metrics respond to arrival rates and behavioral variations. This provides a flexible framework, supporting decision-making for infrastructure planners and offers guidance on trade-offs between costs, sustainability, and service quality.
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    Investigating factors influencing blue-winged teal movements and habitat selection during the nonbreeding season
    (University of Missouri--Columbia, 2025) Edwards, Jeffrey; Webb, Lisa; Fowler, Drew
    Migration is an important life history strategy used by waterfowl to access seasonally available resources. However, migratory events in both autumn and spring are energetically demanding and migration strategies that minimize energy expenditure could offer opportunities for increased fitness. Although waterfowl may initiate seasonal migrations based on a range of favorable environmental factors that minimize energy expenditure, risk of mortality, and maintain or improve body condition, most studies have investigated these relationships at the population level using abundance and occupancy metrics. In this study, we used data from individual GPS/GSM-tracked blue-winged teal (Spatula discors) to evaluate the environmental drivers of autumn and spring migration phenology during 2020 -- 2023 (n = 321 migratory movements) at a continental scale. We modeled departure probabilities of blue-winged teal using logistic exposure models to evaluate how environmental factors influence autumn and spring migration initiation dates as well as subsequent departures from migration stopover sites. We developed candidate models to predict probability of departure, conditional on environmental covariates (e.g., photoperiod, wind bearing and speed, atmospheric pressure, precipitation, visibility, temperature, soil temperature, and low cloud cover) measured at a 32 km2 resolution. Additionally, we evaluated models that included a binary harvest season covariate in our autumn migration analyses to test if departure probabilities were conditional on hunting season (e.g., open vs closed). Departure probabilities in spring and autumn were most influenced by photoperiod although the effect was greatest for spring migration initiation movements. Departure probabilities increased with favorable wind conditions (i.e., tailwinds); however, the effect was greatest for subsequent migratory movements in spring. Autumn departure probabilities of subsequent migratory movements increased with accumulated precipitation, suggesting that blue-winged teal may respond rapidly to proximate wetland conditions. Blue-winged teal are likely to initiate migratory movements based on photoperiod, but may use proximate, local environmental cues (e.g., favorable wind conditions) to time subsequent migratory movements. Importantly, our results indicated hunting season was not associated with autumn migration departure probabilities. Our findings provide some of the first insights into the individual responses of blue-winged teal to environmental factors during autumn and spring migrations which may help inform management decisions from both a harvest and habitat management perspective.
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    A functional analysis of growth hormone receptor promoter regions in swine
    (University of Missouri--Columbia, 2025) Denton, Alicia Nicole; Lucy, Matthew; Safranski, Timothy
    Growth hormone (GH) and its receptor (GHR) play critical roles in regulating growth, development, and reproductive function in animals. GHR expression in the liver is critical for postnatal growth and is regulated by tissue-specific promoters. While promoter 1 (P1) is considered the primary hepatic promoter in species such as cattle, the role of P1 and promoter 2 (P2) in pigs remains poorly defined. This study used CRISPR/Cas9 to generate pigs with bi-allelic knockouts of either P1 (P1KO) or P2 (P2KO) to evaluate the promoter-specific regulation of hepatic GHR signaling and systemic growth. P1KO pigs exhibited normal hepatic GHR and IGF1 expression, normal circulating GH and IGF1 concentrations, and no differences in postnatal growth compared with wildtype (WT) littermates. In contrast, P2KO pigs showed marked reductions in GHR1B, total GHR, and IGF1 mRNA in both liver and muscle, accompanied by elevated circulating GH and lower IGF1 concentrations compared with WT. These endocrine changes were associated with impaired postnatal growth, with P2KO pigs consistently weighing less than WT animals. Despite this, P2KO females were capable of lactation, though fetal growth and litter size were reduced. These findings suggest that promoter 2, not promoter 1, is the primary regulator of hepatic GHR expression and somatotropic axis coupling in pigs. The results highlight species-specific differences in GHR regulation and underscore the functional importance of promoter 2 in supporting postnatal growth and metabolic function. This study also demonstrates the efficacy of targeted gene editing to dissect promoter-specific gene function in livestock.
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    Identification of small molecule inhibitors targeting Cache Valley virus replication and establishment of reverse genetics for swine mammalian orthoreovirus
    (University of Missouri--Columbia, 2025) Khalid, Muhammad Afnan; Ma, Wenjun
    Bunyaviruses are important zoonotic pathogens, and many of them are highly pathogenic and cause severe diseases with high mortality in infected humans. Cache Valley virus (CVV), an emerging bunyavirus, is an arthropod-borne, tri-segmented, enveloped RNA virus of veterinary and public health significance. CVV affects many mammalian species, most commonly causing central nervous system defects and abortions in sheep and goats, and a few human cases with neurological illness have been reported from different parts of the USA. Currently, no commercial vaccines and antivirals are available for human and animal use. To develop an antiviral with broad-spectrum activity against different bunyaviruses, our group has performed high-throughput screening of more than twenty-six thousand small molecules predicted to penetrate the blood-brain barrier and identified 239 small molecules with antiviral activity against the Rift Valley Fever Virus (RVFV) MP-12 vaccine strain expressing Ranielle Luciferase. Thirty-five small molecules were selected for further investigation. In this study, we screened these thirty-five small molecules against the CVV human isolate using the gold standard plaque reduction assay and identified 11 compounds that showed effective inhibition of CVV replication. To explore the mechanism of identified compounds that inhibit CVV replication, we established a minigenome reporter assay and tested them. Results showed that three compounds significantly reduced luciferase expression compared to positive (Ribavirin) and mock controls, indicating that these compounds potentially target viral polymerase RdRp of CVV, thereby inhibiting viral replication. One compound has been demonstrated to effectively inhibit two other bunyaviruses, RVFV and Andes virus, by our group. Our results indicate that this compound could be a good antiviral candidate with broad-spectrum activity against different bunyaviruses. We will further test its efficacy against other bunyaviruses and optimize it in order to develop safe and effective broad-spectrum antivirals against emerging bunyaviruses that threaten human and animal health. Mammalian Orthoreovirus (MRV), a member of the Reoviridae family, infects various mammalian species, including humans, and is important for veterinary and public health. Due to its segmented genome, it can reassort among different strains when they infect the same host, resulting in novel and virulent strains. Our group has isolated reassortant MRVs from US bats and swine, which can infect human, swine, and canine cells without prior adaptation. Our pig studies reveal that both swine MRV1/Porcine/USA/2018 and bat MRV1/40/Bat/USA/2018 viruses are able to infect and replicate in pigs, but they show different tissue tropism. The swine isolate was dominantly detected in the gastrointestinal tract of infected pigs, while the bat isolate was restricted to the respiratory tract of infected animals. We hypothesize that the different tissue tropism of both swine and bat MRVs is due to the S1 segment-encoded surface sigma-1 protein, which is the major attachment protein and binds to the host receptor. To test our hypothesis, I attempted to establish a reverse genetics system for the novel porcine MRV1/Porcine/USA/2018 isolate and then rescue a recombinant swine MRV with the S1 segment from the bat MRV1/40/Bat/USA/2018 isolate. I constructed ten plasmids containing ten gene segments from the porcine MRV under the T7 promoter with conserved sequences at both the 5' and 3' UTRs for each gene and confirmed them by sequencing. The swine MRV was not successfully rescued despite multiple attempts and modifications. It is expected that the failure to rescue the porcine MRV can be resolved in the future. Additionally, to understand the seroprevalence of MRVs in pigs, we have established an in-house ELISA assay to detect MRV-specific antibodies. In this ELISA, we coated the whole virus (MRV1/Porcine/USA/2018) as an antigen and screened pig serum samples collected from different parts of the USA. I have screened 405 samples and found that 240 were positive for MRV, with a 60 percent positive rate. In the future, these MRV-positive serum samples will be further characterized by the HI assay. This result indicates a high seroprevalence in the US swine population, suggesting that MRV could pose threats to animals when co-infected with other pathogens.