Browsing by Author "Oziolor, Elias M., 1990-"
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Item Development and application of high-throughput sample preparation methods for solid matrices.(2014-09-05) Aguilar Lázaro, Lissette.; Usenko, Sascha.; Ecological, Earth, and Environmental Sciences.; Brooks, Bryan W.; Oziolor, Elias M., 1990-; Matson, Cole W.; Robinson, Eleanor Marian.; Trumble, Stephen John.; Williams, E. Spencer.; Subedi, Bikram.; Bigorgne, Emilie.; Horstmann-Dehn, Lara.; Baylor University. Institute of Ecological, Earth and Environmental Sciences.This research presents the development and application of high-throughput sample preparation methods for the analysis of organic and inorganic contaminants from solid samples. The approach presented evaluates conventional methods to identify potential areas of improvement. In this sense, conventional methods serve as a framework for the development of high-throughput sample preparation methods. In general, improvements include expansion of target analyte list thereby increase the environmental applicability, reduction of sample preparation steps, and as a result, reduction of sample preparation time. The analytical bottleneck is often associated with sample preparation, especially in the analysis of organic contaminants from environmental samples. Many environmental analytical chemistry methods can be broken down into one or more sample preparation steps followed by one or more chemical analysis steps. Improvement of historical methods has focused on the development of advance instrumentation (i.e. focusing on the chemical analysis). However, recent efforts have focused on the overall reduction of time and/or steps associated with sample preparation. For example, post-extraction cleanup adsorbents can be incorporated into the pressurized liquid extraction step to perform a selective pressurized liquid extraction (SPLE). SPLE methods significantly reduced sample preparation time, solvent requirements, and waste production. Specific examples presented in this dissertation include: 1) the development and application of SPLE methods for the analysis of organic contaminants from sediments and biological tissues; 2) the development and application of a simplified acid digestion method for the analysis of mercury and selenium in rare samples of Pacific walrus (Odobenus rosmarus divergens) muscle (L. dorsi). These examples illustrate the approach for the development of high-throughput sample preparation methods that have successfully combined techniques into a single method, and/or eliminated post-extraction cleanup steps. The availability of these methods increases laboratory’s capacity and preparedness to analyze rapidly large volumes of samples. These methods could find use in routine analysis and monitoring studies of environmental samples, food and pharmaceutical industries, agriculture, toxicology studies, and forensic sciences among others. Lastly, this dissertation discusses a few opportunities that lay ahead for improvement and development in sample preparation.Item Evolution to pollution in Gulf killifish (Fundulus grandis) from Galveston Bay, TX, USA.(2017-07-27) Oziolor, Elias M., 1990-; Matson, Cole W.Anthropogenic contamination associated with industrial activity is a widespread and active threat to the stability of organisms. The Houston Ship Channel (HSC) is one example of a heavily impacted environment, where industrial activity has contributed to extreme levels of pollution with various classes of contaminants, such as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). This dissertation studies the impacts of chronic multi-generational exposure to industrial contamination on the population structure, resistance and demography in a keystone coastal species – Gulf killifish (Fundulus grandis). We have characterized their sensitivity to contaminants in populations from 12 locations across Galveston Bay, as well as the contamination levels at those sites. We found a gradient of resistance that was positively correlated with contaminant concentrations. This resistance was also correlated to a suppression of the aryl hydrocarbon receptor pathway (AHR), as estimated via the activity of a down-stream regulated enzyme – cytochrome P450 1A (CYP1A). To better understand the impacts of this adaptation, we evaluated the cross-resistance and fitness cost of populations to mechanistically and environmentally relevant stressors, but we were unable to confirm any fitness costs. We showed that the heritability of this resistance is biparental and multi-generational, which suggest that this is a genetic trait. Finally, we performed a full genome resequencing of seven populations along this gradient of resistance and discovered that genomic regions under selection in adapted populations included the AHR pathway. To determine if regulatory benchmarks on the compounds driving this adaptation would protect from such events, we performed a meta-analysis of all evolutionary events to contamination with PCBs and PAHs and found several locations, in which populations have adapted at values below regulation. Here we show that Gulf killifish populations have undergone a rapid evolutionary adaptation to a gradient of anthropogenic contaminants in Galveston Bay. In addition, we suggest that evolutionary toxicology studies, as described here, can be informative for regulatory purposes for compounds that may drive population-wide change.