Sorting Out Sortases: Designing a Better Enzyme and Synthesizing Trapping Peptides Towards Capturing a Bound-State Structure

Sortase A is a powerful protein engineering tool that cleaves proteins and attaches them to an acyl acceptor of choice. However, the most active wild type variants of sortase A only show high activity at a limited number of cleavage motifs, and so work is underway to create a variant of sortase A that shows high activity at a greater variety of cleavage sites. Additionally, current studies attempting to optimize the enzyme require a way to stabilize an unstructured loop for the crystallization, in order to collect X-ray diffraction structural data. Here, preliminary results from the design of an “loop-swapped” sortase A enzyme variants are discussed, as well as the synthesis of two different thiol-containing “trapping” peptides intended to freeze sortase A in its bound conformation via a covalent disulfide bond. The first peptide is a previously described unnatural peptide, and was discontinued before completion, and the second peptide is a natural peptide which was completed and purified. Future work will involve the co-crystallization of this peptide with “loop-swapped” sortase A variants

Food Insecurity as a Predictor of Hurricane Exposure among Underserved Adolescents

Low-income populations are at increased risk for experiencing negative hurricane exposures and food insecurity. However, little is known regarding how pre-hurricane food insecurity experiences are related to youth hurricane exposure. This study examined the types of hurricane disaster exposures low-income, ethnic minority adolescents experienced during Hurricane Harvey and examined the association between food insecurity and hurricane exposure. Low-income adolescents (n = 185) were recruited from a Houston-area school district. Two days before the hurricane, food insecurity was assessed. Adolescents with at least one affirmative answer on the 9-item USDA Child Food Security Survey Module were classified as food insecure. Adolescents self-reported hurricane exposure three weeks post-hurricane using both the National Child Traumatic Stress Network Hurricane and Assessment Referral Tool and Survey of Hurricane Katrina Evacuees. Affirmative answers to lacking access to food, water, or medicine, being rescued, home damage, and displacement were each given a score of one and summed to create an overall hurricane exposure score. A covariate-adjusted linear regression model regressed overall hurricane exposure onto food insecurity. Separate covariate-adjusted logistic regression models were performed where each individual hurricane exposure was regressed onto food insecurity. Prior to the hurricane, 46% of adolescents experienced food insecurity and 43% experienced hurricane exposure. Pre-hurricane food insecurity (p = 0.004) and being foreign born (p = 0.033) were associated with increased hurricane exposure. Adolescents who experienced food insecurity had 132% higher odds of lacking access to fresh water (p = 0.047) and 105% higher odds of lacking access to food (p = 0.034) during the hurricane. Food insecurity and immigrant status appear to be at-risk indicators for hurricane exposure. Schools serving underserved adolescents could consider assessing food security and immigration status as part of disaster preparedness programs

Atlantic Bodies: Health, Race, and the Environment in the British Greater Caribbean

This dissertation examines the relationship between race and bodily health in the British West Indies and the Carolina/Georgia Lowcountry from the late seventeenth through the early nineteenth century. In the eighteenth century, planters often justified African slavery by claiming that Africans, unlike Europeans, had bodies particularly suited to labor in warm climates. Historians have tended to take these claims as evidence of a growing sense of biological race in plantation societies. Much of this work, though, relies on published sources. This dissertation examines these public sources, including medical manuals, natural histories, and political pamphlets, alongside private sources, particularly the personal correspondence of planters and slaveholders to uncover a different story of race and slavery. These two source types reveal significant discrepancies between planters’ public rhetoric and private beliefs about health, race, and the environment in plantation societies. First, correspondence between the Greater Caribbean and Britain demonstrates that health and disease did not contribute to the development of racial slavery in the Atlantic. Second, these sources show how and why planters manipulated public conceptions of climate and health to justify and maintain a system of racial slavery. Planters insisted on climate-based arguments for slavery in spite of their experiences in the Americas, rather than because of them. Slaveholders contributed to the construction of a biological concept of race by making arguments about health differences between Africans and Europeans that they neither experienced nor believed. Nevertheless, their arguments entered the public record and consciousness, and the resultant development of racial thinking had profound consequences that continue to the present day. This dissertation demonstrates the critical importance of the environment to the history of race

Environmental Contaminant Concentrations in Canada Goose (\u3ci\u3eBranta canadensis\u3c/i\u3e) Muscle: Probabilistic Risk Assessment for Human Consumers

The issue of food insecurity affects millions of people in the United States every year. Often these people rely on soup kitchens, food banks, and shelters for proper meals, and these organizations often depend on donations to meet needs. One of the most limited food resources is meat. To help alleviate this problem, the U.S. Department of Agriculture Wildlife Services donates more than 60 tons of wild game (deer, moose, feral hogs, goats, geese, and ducks) to a variety of charitable organizations each year. Although commercially produced meat routinely undergoes screening for contaminants, potential exposure to environmental contaminants from eating wild game is not well characterized. In this study, the concentration of 17 contaminants of concern in the breast meat of wild geese was examined. These concentrations were then used in a probabilistic model to estimate potential risk associated with consumption of this meat. Based on model predictions, more than 99% of all adults were below exposure limits for all of the compounds tested. For all consumer age classes modeled, consumption of wild goose meat may expose a small fraction of these populations to levels of lead higher than the recommended exposure limits. Similarly, mercury exposure was predicted to be higher than the recommended limits when the meat was served as steaks. This information about concentrations of contaminants of concern in goose meat and potential exposures associated with meat consumption based on probabilistic models will enable others to make informed decisions about the risks associated with the consumption of wild meat

Environmental Contaminant Concentrations in Canada Goose (\u3ci\u3eBranta canadensis\u3c/i\u3e) Muscle: Probabilistic Risk Assessment for Human Consumers

The issue of food insecurity affects millions of people in the United States every year. Often these people rely on soup kitchens, food banks, and shelters for proper meals, and these organizations often depend on donations to meet needs. One of the most limited food resources is meat. To help alleviate this problem, the U.S. Department of Agriculture Wildlife Services donates more than 60 tons of wild game (deer, moose, feral hogs, goats, geese, and ducks) to a variety of charitable organizations each year. Although commercially produced meat routinely undergoes screening for contaminants, potential exposure to environmental contaminants from eating wild game is not well characterized. In this study, the concentration of 17 contaminants of concern in the breast meat of wild geese was examined. These concentrations were then used in a probabilistic model to estimate potential risk associated with consumption of this meat. Based on model predictions, more than 99% of all adults were below exposure limits for all of the compounds tested. For all consumer age classes modeled, consumption of wild goose meat may expose a small fraction of these populations to levels of lead higher than the recommended exposure limits. Similarly, mercury exposure was predicted to be higher than the recommended limits when the meat was served as steaks. This information about concentrations of contaminants of concern in goose meat and potential exposures associated with meat consumption based on probabilistic models will enable others to make informed decisions about the risks associated with the consumption of wild meat

Senior Recital: Katherine Johnston, clarinet

This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Music Education. Ms. Johnston studies clarinet with John Warren.https://digitalcommons.kennesaw.edu/musicprograms/1295/thumbnail.jp

The Effect of Substructure on Mass Estimates of Galaxies

Large galaxies are thought to form hierarchically, from the accretion and disruption of many smaller galaxies. Such a scenario should naturally lead to galactic phase-space distributions containing some degree of substructure. We examine the errors in mass estimates of galaxies and their dark halos made using the projected phase-space distribution of a tracer population (such as a globular cluster system or planetary nebulae) due to falsely assuming that the tracers are distributed randomly. The level of this uncertainty is assessed by applying a standard mass estimator to samples drawn from 11 random realizations of galaxy halos containing levels of substructure consistent with current models of structure formation. We find that substructure will distort our mass estimates by up to ~20% - a negligible error compared to statistical and measurement errors in current derivations of masses for our own and other galaxies. However, this represents a fundamental limit to the accuracy of any future mass estimates made under the assumption that the tracer population is distributed randomly, regardless of the size of the sample or the accuracy of the measurements.Comment: 9 pages, 8 figures, Astrophysical Journal, in pres

Senior Recital: Katherine Cook, clarinet

This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Performance. Ms. Cook studies clarinet with John Warren.https://digitalcommons.kennesaw.edu/musicprograms/1518/thumbnail.jp