Graduate Theses & Dissertations

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Isotopes of the Caribbean
This research represents the first stable carbon and nitrogen isotope analysis of human bone collagen (n = 29) from the Escape Site (AD 300 - 1000), Saint Vincent. As a two-pronged investigation, this research had the following goals: (1) determining the ideal pretreatment for poorly preserved bones and (2) reconstructing the Escape Site sample population diet. By incorporating powdered specimens, shorter demineralizations and increased acid:sample exposure, higher collagen yields were produced, thereby expanding the sample size for isotopic analysis. Notably, the elemental data suggests that not all isolated collagen was biogenic and was perhaps contaminated by non-collagenous proteins. This highlighted the importance of using multiple criteria to rigorously evaluate collagen based on the full quality indicator profile. In the end, 5 individuals yielded useable isotope data which was consistent with a broad spectrum diet relying primarily on C3 plants as well as terrestrial, reef, nearshore and freshwater fauna. Within the broad region, the Escape Site data was comparable to other islands from the Lesser Antilles and Cuba emphasizing the influence of regional biodiversity as well as the likelihood that the studied population contributed and benefitted from the extensive Saladoid trade networks which existed at the time. Author Keywords: Caribbean, Collagen, Escape Site, Human diet, Saladoid, Stable isotope analysis
Social Anxiety, Theory of Mind, and Executive Function in Late Adolescence and Early Adulthood
Studies that have investigated the relation between social anxiety and theory of mind or executive function have shown that individuals with deficits in these cognitive processes have high levels of social anxiety. However, methodological problems make past findings questionable and difficult to interpret. The current study investigated whether deficits in theory of mind and executive function predicted symptoms of social anxiety in 99 older adolescents and young adults (18-29). On average, participants had moderate levels of social anxiety. Performance on measures of theory of mind and executive function did not predict symptoms of social anxiety. This lack of associations could be due to characteristics of the current sample, methodological differences in the current study compared to past studies, or the type of social anxiety and theory of mind measure used. Implications and directions for future research are discussed. Author Keywords: Early Adulthood, Executive Function, Late Adolescence, Social Anxiety, Theory of Mind
Mfsd8 regulates growth and multicellular development in Dictyostelium discoideum
The neuronal ceroid lipofuscinoses (NCLs), commonly known as Batten disease, are a family of inherited neurodegenerative lysosomal storage disorders. CLN7 disease is a subtype of NCL that is caused by mutations in the MFSD8 gene. MFSD8 encodes a lysosomal transmembrane protein that is predicted to play a role in transporting small substrates across membranes. However, little is known about its role and substrate specificity. Previous work identified an ortholog of human MFSD8 in the social amoeba Dictyostelium discoideum and reported its localization to endocytic compartments. In this study, the effects of mfsd8 loss during Dictyostelium growth and multicellular development were further characterized. Dictyostelium mfsd8- cells displayed increased rates of proliferation and pinocytosis in liquid media. During growth, loss of mfsd8 altered lysosomal enzymatic activities and reduced the intracellular and extracellular levels of autocrine proliferation repressor A. mfsd8- cells grown on a lawn of bacteria formed plaques in a shorter period of time compared to WT cells, providing additional support for the enhanced growth of mfsd8- cells. Upon starvation, the aggregation of mfsd8- cells was delayed, and mfsd8- cells formed more mounds that were smaller in size, which may be attributed to the reduced cell-substrate adhesion and altered lysosomal enzymatic activities observed for mfsd8- cells. Following aggregation, tipped mound formation was delayed, however, loss of mfsd8 did not affect the timing of slug/finger and fruiting body formation. Additionally, slug migration was reduced in mfsd8- cells. These aberrant phenotypes, excluding fruiting body formation, were effectively or partially rescued when Mfsd8-GFP was introduced into mfsd8- cells. Overall, these results show that Mfsd8 plays a role in regulating growth and developmental processes in Dictyostelium via lysosomal-associated functions. Author Keywords: CLN7, Dictyostelium discoideum, Lysosomes, MFSD8, Neuronal Ceroid Lipofuscinoses

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