Theses and Dissertations at Montana State University (MSU)
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Item A comparative approach to refine molecular mechanisms impacting meat quality and carcass characteristics(Montana State University - Bozeman, College of Agriculture, 2021) Schumacher, Madison Lee; Chairperson, Graduate Committee: Jennifer Thomson and Jane A. Boles (co-chair)Fat deposition is important to both producers and consumers. Producers decide when to harvest animals based on a fat endpoint while consumers equate marbling to tenderness. USDA quality grade is determined by physiological age and marbling. While quality grades help provide insight about product palatability, there is too often variation within the same quality grade. The control of fat deposition is important to determination of carcass endpoint and efficiency of production. The purpose of this study was to increase our understanding of the regulation of fat deposition and muscle growth in relation to USDA quality grade, and to utilize a species comparison to highlight genes and pathways regulating these tissues in multiple meat producing species. Fifteen wethers and fifteen steers from the Red Bluff Research Center were fed to end points that represented Standard, Select, and Choice quality grades endpoints for steers while sheep were fed to fat thicknesses typical to industry endpoints. Subcutaneous adipose tissue and muscle samples were collected for gene expression analysis. Loin were removed from each animal for shear force analysis. Shear force analysis showed a significant reduction in shear force values as quality increased in beef (p < 0.05). RNA extracted from the adipose and muscle tissue was sent to Novogene for RNAseq analysis. The largest difference observed in this study was found within the ovine muscle tissue. Comparing Class 3 to Class 1 muscle tissue resulted in 723 genes down regulated and 1,853 genes up regulated. Class 3 to Class 2 showed 1,127 genes down regulated and 2,272 genes up regulated. When comparing bovine samples, there was an equal distribution of up and down regulated genes. Differentially expressed genes were associated with fat metabolism, cellular signaling, and inflammation in beef. Poor annotation limited the functional analysis of differentially expressed genes in sheep. This study emphasized the need for additional studies evaluating the relationship between gene expression and fat deposition.Item Post-prandial serum concentrations of Trimethylamine-N-oxide in overweight and obese adults with low and high systemic inflammation(Montana State University - Bozeman, College of Education, Health & Human Development, 2018) Wilson, Stephanie Michelle; Chairperson, Graduate Committee: Mary P. MilesPurpose: Elevated trimethylamine-N-oxide (TMAO) levels have been implicated in the development of atherosclerosis. The impact of a high-fat meal on the post-prandial TMAO response in healthy overweight and obese adults was explored, accounting for additional variables that may affect the rate of TMAO conversion. Methods: Forty overweight and obese men and women participated in a high-fat meal challenge containing 50 g fat. Blood samples were collected at fasting and hourly in the 4 hours after meal ingestion and tested for concentrations of TMAO, liver enzymes, lipids, creatinine, insulin, and inflammatory markers. An initial mixed-effects model was constructed to analyze TMAO changes in participants who classified as having low or high levels of systemic inflammation accounting for factors that may influence TMAO concentrations. Backward refinement of the initial model was performed based off p-values. Results: Model refinement found that the log TMAO response was best explained by inclusion of estimated glomerular filtration rate (eGFR), insulin over time, a linear interaction between time and inflammation phenotype, and random effects on subject. Log TMAO after the meal was not different between inflammation phenotypes (p = 0.33). Estimated GFR was the most important determinant in the log TMAO response (p = 0.03), with lower log TMAO observed with higher eGFR values. In conclusion, serum TMAO concentrations during a high fat-meal challenge were strongly determined by eGFR, but not by fasting inflammation status.