Electronic Theses and Dissertations
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Browsing Electronic Theses and Dissertations by Department "Biological Sciences"
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Item A comparison of factors affecting the small-scale distribution of mercury contamination in a Zimbabwean stream system(2017-04-18) Green, Corey S.; Thies, Monte L.; Lewis, Patrick J.; Wozniak, Jeffrey R.Artisanal small-scale mining (ASM) operations use mercury liberally in the gold extraction process, as compared to large scale industrial mining operations, and accounts for approximately one third of anthropogenic mercury consumption worldwide. These ASM operations are concentrated in many impoverished and poorly regulated countries such as Zimbabwe, resulting in a number of negative environmental and health impacts. There are three pathways by which mercury generally enters the environment from gold mining: 1) directly via private miners, 2) through stamp mill operations (also used by ASM miners), and 3) industrial-scale mining operations. To examine the levels of mercury contamination resulting in one such geographic locality, sediment and tailing samples in a single, heavily mined watershed in southern Zimbabwe were collected from May – June 2015. Samples were collected from the stream system, as well as six stamp mills and a single industrial mine in the watershed. GPS point location data were taken for mining operations and sampling sites to examine the spatial patterns of mercury concentration relative to each mining operation. Data were first analyzed using linear regression then a MARS model, followed by application of an ANCOVA model to assess the relationship between mercury concentrations and three factors; percent organic carbon, distance downstream, and distance from potential contamination source. Mercury concentrations within the study area ranged between 6-1,541 µg/kg dw (mean 142 µg/kg dw). Analyses of mercury concentrations indicated a positive relationship with percent organic carbon and a negative relationship with distance downstream and distance from potential contamination source. Results from this study will help to elucidate the relationship between gold production and the spatial scale of mercury contamination in aquatic ecosystems in Africa. These data may lead to a better understanding of the relationship between mercury use and community health, which may aid both the local and global communities in regulating mercury contamination of the environment, thereby reducing the suffering and early death of many people in impoverished countries where ASM is commonplace.Item An experimental manipulation of diet and its influence on growth and epidermal lipids in the northern cottonmouth (Agkistrodon piscivorus)(2018-04-13) Weidler, John; Lutterschmidt, William I.I investigated the effect of diet on growth, skin permeability, and lipid content of snake skin. Lipids are a vital source of energy for life and provide the barrier to water loss in snake epidermis. I conducted a study on a captive colony of snakes (Agkistrodon piscivorus), controlling for either a fish (Notemigonus crysoleucas) or a mouse (Mus musculus) diet. Snakes fed a diet of mice gained significantly more mass than snakes on a diet of fish, indicating that increased lipid content in diet has a significant effect on growth. However, I found no significant difference in cutaneous water loss or lipid content between the two diet groups, indicating that lipid content and cutaneous water loss are strong species-specific physiological performance traits not influenced by recent dietary history. Using IR spectroscopy, I found qualitative differences in absorbance and molecular geometry between the dorsal and ventral surfaces of snake skin. The physiological ability to limit water loss likely plays an important role in microhabitat partitioning between copperheads and cottonmouths but is not influenced by the different diets of these sympatric (but not syntopic) species.Item AN EXPLORATORY STUDY ON THE USE OF GAMBUSIA AFFINIS AS A MODEL FOR INVESTIGATING GUT INFLAMMATION AND MICROBIOME CHANGES(2019-11-06) Stetco, Eliana; Primm, Todd; Madhusudan, ChoudharyA complex relationship exists between gastrointestinal commensal microorganisms and their hosts. While it is not entirely understood how commensal microbiota influence the host immune system, it is evident that the two are largely dependent on one another. Disharmony of the healthy GI tract can result in chronic inflammatory bowel diseases, such as Crohn’s disease (CD) or ulcerative colitis (UC). In the healthy GI tract, the lower intestine is largely hypoxic, thus it is expected to be largely dominated by anaerobes. However, inflammation in the large bowel results in dysbiosis of the microflora such that obligate anaerobes decrease in number while the presence of facultative anaerobes increases. As previous literature demonstrates, this could be due to the fact that inflammation in the host generates reactive nitrogen and reactive oxygen species, molecules that facultative anaerobes can use as final electron acceptors in anaerobic respiration. Further, use of antibiotics could result in persistent alterations in the gut microbiome composition that mimic the alterations seen in the inflamed gut, as antibiotic use in humans sometimes improves irritable bowel conditions and sometimes worsens them. Fish were exposed to dextran sodium sulfate (DSS) orally, with gut inflammation monitored using the MPO assay, gut nitrate levels determined, and gut microbiome community analyzed using 16S sequencing. In conclusion, inflammation levels were inconsistent, possibly because these invasive fish are so resilient and DSS levels were insufficient, or the presence of parasites as a confounding factor. Gut community changes were observed but statistical significance not established. These fish are not a good model for mammalian gut research, as they are normally dominated by facultative anaerobes, while mammalian by obligate anaerobes.In conclusion, it is possible that the amount of DSS used in this explorative study simply is not enough to induce colitis in Gambusia affinis, which are known for being rather resilient fish. Furthermore, it is possible that wild caught Gambusia have too many inherent confounding factors to be used reliably in gut microbiome research and thus further work is necessary.Item Analog vs digital: Testing the comparability and compatibility of diceCT and gross dissection, with special emphasis on muscle tissueLevy, Justin; Lewis, Patrick JDiffusible iodine-based contrast-enhanced computed tomography (diceCT) is a new tool in the study of anatomy. With diceCT, researchers can visualize in situ soft tissue, in three dimensional space. The relationship of these results to traditional gross dissection is unknown. Despite this, it has begun to be used for quantitative comparisons. This approach requires more research to determine the comparability of diceCT and gross dissection. To study the relationship of these two methods, the head of a common marmoset, Callithrix jacchus, was stained in 2.5% Lugol’s solution (I2KI) for 37 days. The head CT scanned for digital dissection prior to physical dissection. Amira 5.6 was used for digital segmentation to reconstruct connective, epithelial, muscle, and nervous tissues. Masses of muscle were taken for muscle density comparisons to the previously established mammalian muscle density constants. Based on Bland-Altman analyses, gross dissection and diceCT do not produce comparable measurements in all circumstances. Muscle and epithelial tissue, as well as volumetric measurements are significantly different between gross dissection and diceCT. Muscle densities were also found to be significantly different than previously established constants, through the use of one sample t tests. New, diceCT-calibrated constants are proposed for use with specimens that cannot be dissected. Muscle density is not constant, and should not be treated as such. This process is still widely beneficial when traditional destructive dissection is not possible. It allows for three dimensional views of structures that are not otherwise visible due to size and/or morphology, however, comparisons between gross dissection and diceCT should be approached with caution.Item Analyses of Metacaspase 1 and a Potential APAF-1 Orthologue During Heat Stress-Induced Programmed Cell Death in Chlamydomonas reinhardtii(2017-04-18) Catumbela, Celso Santos Goncalves; Gaillard, Anne; Primm, Todd; Harper, JamesPurpose The purpose of this thesis was to expand on the knowledge of the PCD machinery of unicellular eukaryotes. To this end, the first half of this thesis employs the single cell green alga, Chlamydomonas reinhardtii, and examines the potential roles of metacaspase type I (MCA1) in modulating the events of programmed cell death (PCD). The second half of this thesis attempts to elucidate the function of a potential orthologue of APAF-1, a key apoptotic protein reported in multicellular eukaryotes, and hypothesized to be present in the unicellular C. reinhardtii. Methodology Using an MCA1 knockout strain of C. reinhardtii (mca1), verified via PCR and DNA sequence analysis, the first half of this thesis utilizes the following techniques to reveal the potential roles of MCA1: fluorescence microscopy and DNA laddering, as well as colony formation and colorimetric assays. All experiments were conducted in triplicate. The data was analyzed via manual cell counts, and qualitative analyses were performed by a single analyst. Statistical software (SAS 9.4 and JMP 13) analyses were conducted by two independent personnel. For the second half of this thesis, proteomic analysis of C. reinhardtii was conducted through usage of whole-cell extraction, sucrose gradient centrifugation, SDS-PAGE, Coomassie blue staining, and Western blotting. Findings Genetic analysis of mca1 revealed that the disruption of MCA1 is linked to the rapid transmission of certain PCD events due to heat stress in C. reinhardtii. Results show that in response to heat stress, MCA1 knockout is associated with significantly increased plasma membrane disruption in C. reinhardtii. Moreover, heat-stressed mca1 cells consistently displayed increased DNA laddering, relative to WT. Furthermore, in response to heat stress, mca1 populations displayed more rapid accumulation of ROS, as well as a significantly greater ROS response with prolonged heat stress exposure. Notably, MCA1 knockout did not alter the rate of phosphatidylserine (PS) externalization, or cell proliferation upon the onset of heat stress. Together, our data suggest the potential that MCA1 acts as a negative regulator of certain heat stress-induced PCD phenotypes within C. reinhardtii. In the second half of this thesis, proteomic analysis revealed that prior published results suggestive of APAF-1 presence in C. reinhardtii could be generated in the absence of antibodies against human APAF-1. Intriguingly, comparable results were obtained through sole usage of goat anti-rabbit IgG, or goat anti-mouse IgG (1:5000, both). Moreover, in silico analysis revealed the primary APAF-1 homologs in C. reinhardtii to lack key conserved domains (CARD and AAA16). Together, the biochemical and in silico data refuted the previous report of a potential APAF-1 orthologue in C. reinhardtii. This thesis provided novel data to aid in the understanding of the unicellular PCD machinery, as well as recommendations for future studies.Item Analysis of Gold Tolerance in Rhodobacter sphaeroides(2016-10-25) Johnson, HannahHeavy metal pollution is a worldwide problem with many associated health risks, including bone loss, kidney damage, and several forms of cancer. There is a great need of bioremediation of these toxic metals from the environment, as well as implementing a monitoring system to control the spreading pollution. This study focuses on the bioremediation potential of R. sphaeroides in the presence of the toxic gold chloride (AuCl3). A bioinformatics approach is taken to identify all heavy metal related genes within 2,489 bacterial species, identify the genes potentially involved in their bioremediation within the genome of R. sphaeroides. Growth characteristics of the bacterial cells exposed to a range of toxic gold concentrations were analyzed through the growth kinetics and the colony forming units (cfu’s) under aerobic, photosynthetic, and anaerobic growth conditions. The localization of the gold particles within two cellular fractions, cytoplasmic and the plasma membrane, are analyzed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The results of this current study reveal the majority (46%) of the heavy metal related genes belong to the species within the Proteobacteria group, and subsequently the αProteobacteria. Upon analysis of the R. sphaeroides genome, 475 heavy metal related genes were identified. Results also reveal the photosynthetic growth condition as best suited for the metal tolerance, allowing a higher survivability under the gold concentrations compared to subsequent growth conditions. Results of the localization revealed the overall accumulation of gold particles, while not different between the cellular fractions, increased at different concentrations of the gold contamination. The results of the photosynthetic localization revealed the accumulation reached the highest very quickly, and an overall shift in localization of the gold particles from an equal distribution to an increase within the membrane fraction at the highest concentrations of gold contamination. Expression profiles of the heavy metal related genes within R. sphaeroides, 369 in total, reveals a total of 46 photosynthetic genes which will be the targets of molecular analysis in the future work.Item Characteristics of miniaturization in squamates: A phylogenetic perspective from cranial morphologyVallejo, Maria Camila; Daza, Juan D.Miniaturization is recurrent in tetrapods, and has been widely recognized to be an evolutionary process resulting from the occupation of previously unexploited niches (Hanken and Wake, 1993; Rieppel, 1984a, 1996). In this thesis I review the process of miniaturization and its effects on the skull of squamates (lizards, snakes, and amphisbaenians). I compiled a list of characteristics previously described for squamates and summarized the main differences among higher level groups (e.g., Iguania, Gekkota or Scincomorpha). I also investigated whether observed traits linked to miniaturization are the product of convergent evolution. I used a large published morphological data set that includes 204 species of which 54 are miniaturized. I coded characters for an additional species that represent the smallest known squamates (e.g., Sphaerodactylus ariasae and Brookesia micra) and belong to taxonomic groups with minor representation in the original dataset. Analyses identified two characters that occurred in miniaturized taxa of 15 mm or less in skull length, six characteristics for species with 10 mm or less, three for species with 5 mm or less, and eight traits convergent to miniaturized head-first burrowers.Item Comparison of Endohelminth Parasites in Alligator Gar (Atractosteus Spatula) and Spotted Gar (Lepisosteus Oculatus) from Sabine Lake(2021-08-01T05:00:00.000Z) Thorn, Chelsea S; Cook, Tamara; Smith-Herron, AutumnAlligator gar (Atractosteus spatula) and spotted gar (Lepisosteus oculatus) are predatory, primitive fishes with a long evolutionary history. Both species are native to North America and are distributed through the gulf coast. The parasites of these 2 species are understudied throughout their range, but particularly in coastal Texas. This study examined the endohelminth parasite communities of these 2 species in a unique study habitat (Sabine Lake Estuary). A helminth survey of 40 alligator gar and 40 spotted gar was conducted on specimens captured from Sabine Lake in the spring and summer of 2018. Parasitic intensity and Shannon-Wiener diversity were calculated for each fish individually and then regressed against host size and habitat salinity to determine if these variables influence parasite community. The communities of the 2 species were then compared using Shannon-Wiener diversity, Percent Similarity index, and a mixed effect model. From these samples, 13 parasite species were identified (5 trematodes, 4 nematodes, 2 cestodes, and 2 acanthocephalans), 10 of which were shared by both host species. Host size and salinity were not found to be significant predictors of parasite community diversity. This study is significant as a survey of endohelminths from Sabine Lake that documents new host and localities for several parasite species as well as highlighting the diversity of parasite species found in gar captured from a saline environment.Item COMPARISON OF ENDOHELMINTH PARASITES IN BLACK DRUM (POGONIAS CROMIS) AND RED DRUM (SCIAENOPS OCELLATUS) FROM THE SABINE LAKE ESTUARY(2021-05-01T05:00:00.000Z) McNeese, Hannah Casey; Cook, Tamara; Smith-Herron, AutumnThe black drum (Pogonias cromis) and the red drum (Sciaenops ocellatus) are two closely related fish species that occur throughout the Gulf of Mexico. These species utilize estuarine systems as brooding grounds for their young, which offers some protection, and readily available food sources to the juvenile individuals. This study sought to understand how endo-parasitic communities of juvenile and sub-adult individuals of these two drum species compared, and sought to determine what the effects of host size and habitat salinity were on the parasitic communities in each fish species and between fish species. We conducted a helminth survey on black drum (n=59) and red drum (n=61) that were caught from Sabine Lake in the spring and summer of 2018. The overall parasitic intensity and the Shannon-Wiener diversity were calculated for each individual fish, and were compared to host size and habitat salinity, respectively, via linear regression to determine effects of the factors on the parasite community. Parasitic communities were compared between fish using Jaccard’s index, Hutcheson-t test of Shannon-Wiener diversity, Percent Similarity index, and a mixed-effects model. Percent similarity index and the mixed effects model were used to determine if host size and habitat salinity affected the similarity of the parasitic communities to one another. From these fish we have identified 38 parasite species (23 nematodes, 6 trematodes, 5 acanthocephalans, and 4 cestodes). The relationship of host size and intensity of parasitic infections was found to be significant for both the black (R2=0.29, p<0.05) and the red drum (R2=0.16, p<0.05). The Jaccard index value was 0.2895, or 28.95% similarity between the communities, and Hutcheson-t did show significant difference (p<0.05) in diversity between the two communities. The highest percent similarities were between the small sized black and red drum, and between the black and red drum caught in the lowest salinities. This study is significant as a primary helminth survey from Sabine Lake, and as new host and locality documentations for several parasite species.Item COMPARISON OF MICROBIAL COMMUNITIES IN SOIL SEDIMENTS IMPACTED BY MERCURY CONTAMINATION ALONG A GRADIENT IN THE TRINITY RIVER, TEXAS(2022-08-01T05:00:00.000Z) Manandhar, Sujina; Choudhary, Madhusudan; Primm, Todd P; Atkins, Mardelle R; Montaña Schalk, Carmen GHeavy metal contamination in the freshwater ecosystem has become a serious global issue impacting ecological, environmental, and human health. Over decades, the Trinity River in Texas has become polluted with several toxic heavy metals, including mercury (Hg), due to intensive anthropogenic activities and natural sources. The combustion of coal in power plants to generate electricity and several other Hg sources have led to mercury pollution in this river system. This study aims to i) determine the concentration of mercury in soil sediments along the gradient of the Trinity River, ii) investigate the soil microbial communities in the sites along the Trinity River that are impacted by mercury contamination, iii) examine the soil sediments to find whether the sites closer to coal-fired industries have higher mercury concentrations compared to the sites that are distantly located from coal-fired industries along the Trinity River, and iv) to determine if the soil sediments of the sites contaminated with high mercury concentration were enriched with mercury methylating genera compared to the non-contaminated sites leading to shift in microbial composition and diversity. The findings of the study supported our hypothesis that there is a relatively higher concentration of mercury in the downstream site of the river, but it remained inconclusive that the sites closer to coal power plants have higher mercury concentrations, since most tributaries carries the industrial waste effluents generated by these power plants flow into the main channel of Trinity River farther from the sites where soil sediments were sampled. On the other hand, the result of the microbial diversity analysis showed that statistically, there is no significant difference in microbial composition (alpha diversity and beta diversity) between the uncontaminated upstream locations and contaminated downstream locations. While certain groups of mercury methylating genera were present in relatively higher abundance in sites with the increased level of mercury. The study suggests that; besides mercury, several other physicochemical factors of river water and soil sediment might contribute to emerging a synergistic microbiome composition at these sites, and while only small microbial differences lead to affect mercury metabolism.Item Determining the interactions between serum proteins of the complement system and outer membrane proteins in avian pathogenic Escherichia coli(2017-11-08) Botero, Cindy; Lynne, Aaron M.Eschericia coli is a well-known member of the intestinal flora of mammals and birds. However, there exist pathogenic strains capable of causing disease. One strain comes from the O-serogroup of E. coli, APEC O2 (+/+), and causes millions of dollars of global losses annually. The elucidation of the mechanisms of complement avoidance in pathogenic strains could potentially provide vital information to understanding bacterial pathogenicity and assist in the future development of a vaccine. The bacterial strains used were APEC O2, an iss+/bor+ strain, and DH5α, a iss-/bor+ strain. Mutant strains were created from a knockout of iss in APEC O2 (+/+) to create APEC O2∆iss (-/+), and a knockout of the gene bor to create DH5α∆bor (-/-). In order to determine how Iss and Bor assist each other in surface exclusion tactics and in serum resistance, each strain was subjected to a complement consumption assay, which measured the amount of complement consumed by each strain, the bactericidal assay, which determined the amount of cell death in response to complement, ELISA, which measured the amount of terminal complement complex remaining after exposure of bacteria to serum, and immunofluorescent microscope visualization, which visually showed the bound C5b-9 terminal complement complex to the outer membrane of the bacterial strains. The results of this study determined that the role the protein Bor has on assisting Iss with serum resistance may not be as significant as previously thought. There may also be something other than the gene bor assisting iss in the prevention of cell death due to the attachment of membrane attack complex (MAC) on the cell wall. This study expands on our previous understanding of how proteins of the outer bacterial cell membrane cooperate in order to provide resistance to complement proteins in the immune system.Item DOC AS A DRIVER OF MICROBIAL DIVERSITY IN AN EAST TEXAS FLUVIAL NETWORK(2024-05) Lannom, Max Logan; Ulseth, Amber J; Harper, James M; Lynne, Aaron MFreshwater stream ecosystems are rich in microbial life and various environmental factors may influence the diversity of these microbial communities. By virtue of the continuous flow of water from upstream to downstream, rivers form a metacommunity that is linked by downstream dispersal of organic materials and microorganisms. River ecosystems are further complexed with microhabitats such as the benthic zone and the water column. Drawing from ten months of sample data collected from a forested headwater site, this study analyzed correlations between microbial diversity and nine potential drivers: dissolved organic carbon (DOC) concentration and composition, centimeters of rainfall, river kilometers, and water chemistry (total nitrogen, nitrate, and phosphorous). It was found that the diversity of benthic samples was positively correlated with spectral slope ratio and no other variable, while water column diversity was correlated with SUVA254, DOC, rainfall, and negatively correlated with phosphorous in the temporal study. Microbial diversity patterns were also analyzed along a longitudinal continuum (upstream to downstream). The diversity of water samples was found to be positively correlated with Sr, DOC, and river kilometers in the longitudinal study. A clear pattern emerged in which there was higher diversity at the unimpacted large river site than in the headwater sites, but that diversity began decreasing once the river flowed into an artificial reservoir, and especially so downstream of the dam itself.Item DOES BPS CAUSE LIPID SYNTHESIS AND ER STRESS IN HEPG2 CELLS?(2018-11-20) Lollar, David M.; Harper, JamesBisphenol A (BPA) was originally designed as a synthetic estrogen but is now used as a monomer in the production of plastics. Recent research has linked exposure to low doses of BPA, below the reference dose (the safe long-term daily dose) of 50µg (kg1 day-1), with a number of health problems including diminished fertility, insulin resistance, obesity, accumulation of triglycerides in the liver and the induction of endoplasmic reticulum (ER) stress with subsequent non-alcoholic fatty liver disease. Because of the problems with BPA, bisphenol S (BPS) has become a popular alternative in plastic production. However, emerging research has associated BPS with many of the same health problems as BPA. In this study, I examine the effects of low-dose exposure to BPS on HepG2 cells, an established in vitro model system of liver function in use since 1974. More specifically, I monitored the total amount of lipid droplets, and the amount of acetyl-CoA carboxylase (the catalyst of the first, and rate limiting step of fatty acid synthesis) to measure fatty acid synthesis in HepG2 cells exposed to low doses of BPS, and further I examine the levels of ER chaperone protein glucose-regulated protein 78 (GRP78/BiP) to study effects of BPS on ER stress. In short, I found no significant effect of BPS exposure on the cells in that there was no significant change in lipid levels, p-ACC, or GRP78/BiP levels.Item Effect of bisphenol A on stress-induced premature senescence(2016-11-11) Alper, Samantha J.; Haper, James M.; Gaillard, Anne R.; Haines, Donovan C.; Lynne, Aaron M.Plastics are used for a wide variety of commercial applications all over the world, but recently a number of health risks have been linked to plastics and plastic products. For example, bisphenol A (BPA) is a plasticizer used in the production of plastics such as storage containers, plastic bottles, adhesives, and many other everyday objects. BPA-containing plastics are subject to degradation, resulting in the ingestion of BPA from many different sources. BPA has been shown to cause negative side-effects once ingested due to its ability to act as an estrogen mimic, along with being implicated in the formation of cancers and the metabolic syndrome. BPA has also been linked to inducing oxidative stress, which can lead to damaged DNA, promote tumorigenesis, and can cause cell death in extreme cases. On the other hand, little is known about the effect of BPA on cellular senescence, a state of irreversible cell cycle arrest and a recognized barrier to cancer progression. Because of its pro-oxidizing role, it was hypothesized that BPA could increase the likelihood of cells becoming senescent. To test this, cells were exposed to a variety of experimental conditions for varying lengths of time; they were then stained for β-galactosidase, a widely used biomarker of senescence, and interleukin-6, a pro-inflammatory cytokine linked to senescence. It was found that, although BPA may not have a direct effect on senescence induction in a dose dependent manner, dimethyl sulfoxide (DMSO), the vehicle used to dissolve BPA in this experiment, could have an effect on senescence induction at very low doses.Item Effect of Cell Culture Condition or Bisphenol A (BPA) Exposure on the Wound Healing Response In Vitro(December 2023) Hays, Emily E; Harper, James M; Lynne, Aaron M; Ulseth, Amber JWound healing is a process comprised of overlapping phases: inflammation, tissue formation, reepithelization, and remodeling; all of which can be influenced by exogenous factors such as environmental pollutants. Bisphenol A (BPA), a monomer used in the manufacture of many plastics, is an endocrine-disrupting chemical that may influence cell proliferation and/or cellular migration during wound repair. Here I used an in vitro model of wound healing to investigate the effect of varying the composition of the cell culture media in conjunction with BPA exposure to determine how each of these factors may influence the kinetics of the wound healing response. Specifically, the degree of closure over 24 hours was measured in the presence or absence of bovine serum in the cell culture media in cells pre-exposed to varied concentrations of BPA. Using an algorithm developed for ImageJ to autonomously estimate the rate of wound closure, we found that the presence of serum in the culture media significantly increased this rate in (p ≤ 0.001). Prior exposure to BPA had no effect on the rate of wound closure, regardless of dose or cell culture condition (p ≥ 0.05). Collectively, these data suggest that serum growth factors are essential mediators of wound closure in vitro, whereas BPA exposure has no significant effect.Item Effect of Ignatzshineria indica (Gammaproteobacteria: Xanthomonadales) on rate of decomposition in mice(2017-11-06) Madamba, Dorothy C.; Bucheli, Sibyl R.Microbes have a major role from the onset of and throughout decomposition. Studies show that a decomposing body supports a necrobiome (Pechal et al., 2013), a term coined to mean a community of living things associated with decomposition of remains, specifically with reference to microorganisms. The objective of the current study is to show how Ignatzschineria indica, a fly associated, and selected bacteria associated with a decomposing human body affect decomposition under controlled (laboratory) conditions. The work presented here is a laboratory experiment carried out at Sam Houston State University, Huntsville, Texas. To assess the effect of Ignatzschineria indica bacteria on decomposition, 3 batches of 90 mice were subjected to 9 different bacterial treatments involving 4 bacteria; A [Ignatzschineria indica], B [Escherichia coli], C [Bacillus licheniformis], D [Salmonella enterica], and combinations of Ignatzchineria indica and other bacteria in the following manner BA, CA, DA, PC [positive control] and NC [negative control]. 270 mice were observed throughout their decomposition process. Results from this experiment showed that the initial bacteria composition in dead mice does not affect the rate of decomposition under laboratory controlled conditions of temperature and moisture, with the exclusion of vertebrate and invertebrate scavengers. Adding Ignatzchineria indica to dead mice specimens under laboratory controlled conditions does not significantly affect the rate of decomposition but instead affects the pathway of decomposition. This was evident from the different intensities of volatile organic compounds (VOCs) that were collected and assayed from the different samples. The same experiment shows that at any given time the ambient temperature is significantly different from the subjects’ temperatures during decomposition. Our findings lead us to conclude that the addition of Ignatzschineria indica bacteria to decomposing mice does not significantly alter the rate of decomposition. It does alter the chemical pathways of decomposition as evidenced by variant VOCs composition.Item EFFECTS OF URBANIZATION ON ARTHROPOD COMMUNITIES IN CAROLINA WREN (THRYOTHORUS LUDOVICIANUS) NESTS: A COMPARATIVE STUDY BETWEEN URBAN & RURAL HABITATS IN WALKER COUNTY, TEXAS(2019-11-12) Byrd, Faith N.; Neudorf, Diane LHAs urban sprawl increases, the need for better understanding of anthropogenic effects on songbirds also increases. Humans continue to alter natural environments by introducing non-native plant species and disturbing ecosystems with houses and maintained yards. These alterations have been shown in past studies to not only alter animal behaviors, but to affect what animals are present in a given space. This is particularly concerning given recent studies showing a dramatic decline in arthropod populations globally. I evaluated the relationship between plant communities, human dwellings and arthropod communities found in the nests of a cavity-nesting songbird species, the Carolina Wren (Thryothorus ludovicianus) to establish if species richness of arthropods in microhabitats has been affected by human influence. Avian nests are important habitats for arthropod species that live and reproduce in nesting material. Some of these arthropod species impact vertebrate fitness, and many play an important role in nutrient recycling by breaking down decaying materials. The results of this study suggest that urbanization shifts community structure of nest-dwelling arthropods. Species richness was greater in rural habitats and when nests were located near native plants, though species populations between habitats were not significantly different. Future studies should consider more factors of urbanization, as well as the impact of urban densification on other microhabitats.Item ENVIRONMENT INFLUENCES EARLY BUT NOT LATE RECOVERY OF DISRUPTED FISH SKIN MICROBIOME(2020-04-15) Carlson, Jeanette; Primm, ToddDisruption by antibiotics causes instability to the native microbiota, which typically increases host susceptibility to opportunistic infections (e.g. C. diff) that result in correlated diseases, such as antibiotic-associated diarrhea in humans. Other animals such as vertebrate fish also possess an important microbiome residing in the outer mucosal skin layer, which provides essential protection to the host against the consent contact of the surrounding environment. Yet, after undergoing a disruptive event such as antibiotic exposure, our knowledge remains limited to predict how the microbial community will return and how the environment might influence the microbial assemblage during recovery. The focus of this study investigates whether the recovery environment influences the return of the skin microbiota after fish are briefly exposed to a strong dose of the broad-spectrum antibiotic rifampicin. To test this, we placed mosquitofish (Gambusia affinis) into different recovering conditions post-treatment for a week 1) a sterile mimic of pond water, Artificial Pond Water (APW) and 2) an environment where fish were housed in, aquarium tank water. During recovery, the fish skin microbiota and surrounding water were sampled to compare water type conditions. Additionally, two questions were explored 1) does the same taxon arise post-treatment when skin bacterial overgrowth occurs? 2) does the skin mucus layer increase during overgrowth of skin bacteria? Our findings, after rifampicin exposure, show that the recovery environment does influence the bacterial load and structural features (16S rRNA gene sequencing and ERIC-PCR fingerprint profiles) of the fish skin microbial community early in recovery, but later in the week begins to merge into similar microbial assemblages. On the contrary, Microgen ID strips testing the biochemical profile of the returning skin microbiome suggested that fish recovered in APW at 12 hr shared a more comparable profile similarity to pre-treatment-24 hr than to fish recovered in aquarium water. Water chemistry parameters tested with dip strips did not find any significant difference between the APW and aquarium water environments. Throughout recovery in different conditions, the surrounding water bacteria population reflected to the bacterial load found on the fish skin. Our findings showed the environment influences an antibiotic-disrupted fish skin microbiome early and at mid-recovery, but by the end of the week returns to similar outcomes., thus giving partial support to the main hypothesis. Research questions explored during mid-recovery at 60 hr, found that the bacterial load on fish recovered in APW significantly increased during which the genus Comamonas was suspected as the most abundant (52%) taxa, yet more data analysis is needed for confirmation. Staining fish skin mucus with alcian blue was not found to significantly increase on treated fish recovered in APW while bacterial numbers peaked at midrecovery.Item Estimation of Postmortem Interval in Human Cadavers Using Two Different Quantitative Methodologies(2023-05-01T05:00:00.000Z) Sarles, Molly Ruth; Bucheli, Sibyl R; Lutterschmidt, William I; Lynne, Aaron MPostmortem interval (PMI) is defined as the time between death and discovery of the deceased. It is important in criminal investigations because it allows investigators to draw conclusions about the circumstances surrounding the death of a person. The postmortem interval is estimated using many different methods. Currently, the standard of the field is the use of insect succession or physiological age of insect larvae to determine PMI; however, quantitative scoring methodologies have become more common as they aim to allow non-professionals to efficiently estimate PMI in the field. Two quantitative methods of estimating PMI are Vass’ universal PMI formula and Megyesi's total body scoring (TBS) system. However, the validity of these methods across different regions is unknown. We found that actual PMI and PMI estimated using Vass’ universal formula were statistically different from one another (p < 0.001). There was not enough evidence to show that actual PMI and the TBS calculated PMI were statistically different from one another (p = 0.208). We know that decomposition is highly variable and dependent upon region/climate. From this, we can conclude that Vass’ ‘universal’ PMI formula is not a reliable method of estimating PMI in Southeast Texas.Item Evaluating the effects of cheliped morphology on the mating behavior of two invasive crayfish, the Louisiana crayfish (Procambarus clarkii) (Girard, 1852) and the Virile crayfish (Faxonius virilis) (Hagen, 1870)(2019-07-03) Hays, Hayden; Neudorf, Diane L.H.The Louisiana crayfish (Procambarus clarkii) is a large-bodied crayfish that is native to northeastern Mexico and the south-central United States, with a breeding season ranging from June to October in colder climates or June through November in warmer climates, with the inclusion of a second mating in the spring. This system combined with the r-selected characteristics of this species allows it to produce a massive amount of offspring, increasing its potential to become invasive. The Virile crayfish (Faxonius virilis) is native to the Great Lakes region of the United States, and shares similar life history traits with P. clarkii. Despite the extensive research on the invasive potential of these organisms, the visual behavioral aspects of the mating system have been mostly neglected. This study has investigated how cheliped autotomy influences female choice and copulation behavior of these two species of crayfish. Previous studies showed that P. clarkii females preferred males of larger body size or larger chelae size, but not which played a larger role. In other crayfish species, chelae asymmetry has shown no impact on mate choice, but no studies have looked at the impact of chelae loss in mate choice. Chelae loss or injury is fairly common in crayfish due to predatory and intraspecific interactions. I investigated 3 physical traits: chelae presence, function, and chelae-body size ratio in female mate choice. Females were given a choice between two different males to determine the importance of these traits in male mating success in two different experiments. Females of both species showed no preference for males based on any of the visual traits examined. Copulations were infrequent and not indicative of female preference for a particular male phenotype. Chelae function and chelae-body size ratio impacted male copulation attempts for P. clarkii. This suggests that further research must be done to include other visual, and chemical, stimuli to truly understand the crayfish mating system and the role of female choice.