Tissue samples from spotted gar (Lepisosteus oculatus) and largemouth bass (Micropterus salmoides) were collected from Caddo Lake. Gar and bass livers were subjected to histological investigation and color analysis. Liver color (as abs at 400 nm) was significantly correlated with total mercury in the liver (r2 = 0.57, p = 0.02) and muscle (r2 = 0.58, p = 0.01) of gar. Evidence of liver damage as lipofuscin and discoloration was found in both species but only correlated with liver mercury concentration in spotted gar. Inorganic mercury was the predominant form in gar livers. In order to determine the role of mercury speciation in fish liver damage, a laboratory feeding study was employed. Zebrafish (Danio rerio) were fed either a control (0.12 ± 0.002 µg Hg.g-1 dry wt), inorganic mercury (5.03 ± 0.309 µg Hg.g-1 dry wt), or methylmercury (4.11 ± 0.146 µg Hg.g-1 dry wt) diet. After 78 days of feeding, total mercury was highest in the carcass of zebrafish fed methylmercury (12.49 ± 0.369 µg Hg.g-1 dry wt), intermediate in those fed inorganic mercury (1.09 ± 0.117 µg Hg.g-1 dry wt), and lowest in fish fed the control diet (0.48 ± 0.038 µg Hg.g-1 dry wt). Total mercury was …

Baird's pocket gopher (Geomys breviceps) is found in eastern Texas, eastern Oklahoma, central and western Arkansas, and western Louisiana. The cytochrome-b gene was sequenced and analyzed for 16 pocket gophers from throughout the range of the species. Similar phylogenetic trees were obtained using maximum-parsimony, maximum-likelihood, neighbor-joining, and Bayesian analyses. Two major clades were formed with northern individuals belonging to clade I and southern individuals belonging to clade II. G. b. sagittalis was paraphyletic in relation to G. b. breviceps in all analyses. Based on inconsistencies between the taxonomic classification and systematic relationships within Baird's pocket gopher, a taxonomic restructuring appears warranted.

Phloem transport is along hydrostatic pressure gradients generated by differences in solute concentration between source and sink tissues. Numerous species accumulate raffinose-family oligosaccharides (RFOs) in the phloem of mature leaves to accentuate the pressure gradient between source and sinks. In this study, metabolic engineering was used to generate RFOs at the inception of the translocation stream of Arabidopsis thaliana, which transports predominantly sucrose. To do this, three genes, GALACTINOL SYNTHASE, RAFFINOSE SYNTHASE and STACHYOSE SYNTHASE, were expressed from promoters specific to the companion cells of minor veins. Two transgenic lines homozygous for all three genes (GRS63 and GRS47) were selected for further analysis. Sugars were extracted and quantified by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), and 21-day old plants of both lines had levels of galactinol, raffinose, and stachyose approaching 50% of total soluble sugar. All three exotic sugars were also identified in phloem exudates from excised leaves of transgenic plants whereas levels were negligible in exudates from wild type leaves. Differences in starch accumulation or degradation between wild type and GRS63 and GRS47 lines were not observed. Similarly, there were no differences in vegetative growth between wild type and engineered plants, but engineered plants flowered …

Polycyclic aromatic hydrocarbons (PAHs) are a well studied and diverse class of environmental toxicants. PAHs act via the aryl hydrocarbon receptor (AhR), and studies have suggested that PAHs may elicit neurological and estrogenic effects. Doses of PAHs between 50 to 150 ppm may elicit neurotoxicity in rodent models. The present study investigated the effects of naphthalene on in vivo steroidogenesis in Swiss Webster male mice, and in vitro neural function of Balb-C/ICR mice frontal cortex neurons. These data suggest that naphthalene may not elicit steroidogenic effects at concentrations ranging from 0.2 to 25 mg/kg/day, following a 7 day subcutaneous dosing regime. In addition, naphthalene may cause functional toxicity of frontal cortex neurons at concentrations of 32 to 160 ppm naphthalene.

N-Acylethanolamines (NAEs) are endogenous plant lipids hydrolyzed by fatty acid amide hydrolase (FAAH). When wildtype Arabidopsis thaliana seeds were germinated and grown in exogenous NAE 12:0 (35 µM and above), growth was severely reduced in a concentration dependent manner. Wildtype A. thaliana seeds sown on exogenous abscisic acid (ABA) exhibited similar growth reduction to that seen with NAE treatment. AtFAAH knockouts grew and developed similarly to WT, but AtFAAH overexpressor lines show markedly enhanced sensitivity to ABA. When low levels of NAE and ABA, which have very little effect on growth alone, were combined, there was a dramatic reduction in seedling growth in all three genotypes, indicating a synergistic interaction between ABA and NAE. Notably, this synergistic arrest of seedling growth was partially reversed in the ABA insensitive (abi) mutant abi3-1, indicating that a functional ABA signaling pathway is required for the full synergistic effect. This synergistic growth arrest results in an increased accumulation of NAEs, but no concomitant increase in ABA levels. The combined NAE and ABA treatment induced a dose-dependent increase in ABI3 transcript levels, which was inversely related to growth. The ABA responsive genes AtHVA22B and RD29B also had increased expression in both NAE and ABA treatment. …

This dissertation examines the ability of in vitro biotransformation assays to provide an indication of metabolic potential. The potential for xenobiotic compounds to bioconcentrate in aquatic organisms is expressed through the bioconcentration factor (BCF). The metabolic loss of ibuprofen, norethindrone and propranolol was measured using rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) gill and liver S9 fractions, microsomes and cell suspensions. Metabolic transformation rates (kM) were extrapolated from in vitro intrinsic clearance of parent compound (CLm) and integrated into a refined BCF model. In general, CLm of test compounds was greater in liver S9 fractions and hepatocytes. However, the influence of hepatic metabolism on kM and BCF was limited by hepatic blood flow (20-25%) compared to gill blood flow (~100%). A significant difference was noted between BCF solely based on KOW and BCF including kM. These studies indicate that the inclusion of kM in BCF models can bring predicted bioconcentration estimates closer to in vivo values. Primary cell suspensions are preferred over subcellular fractions as cell suspensions possess both phase I and phase II enzyme activity. Further study was conducted on ibuprofen biotransformation pathways. As fish do not contain the same cytochrome P450 (CYP) 2C homologs known to …

Texas currently maintains the highest installed nameplate capacity and does not require publicly available post-construction monitoring studies that examine the impacts of wind energy production on surrounding fauna. This thesis examines potential wind energy impacts on avian and bat species in Texas through a three-part objective. The first two objectives synthesize literature on variables attractive to species within wind development areas and estimate impacted ranges outside of Texas, based on studies examining wind energy's environmental impacts. The third objective focuses on Texas wind development potential for interaction with rare, threatened and endangered species of birds and bats using GIS analysis with a potential hazard index (PHI) model, which addresses broad-spectrum, high risk variables examined within the first two objectives. Assuming areas with higher wind speeds have potential for wind development, PHI values were calculated for 31 avian and ten bat species, based on an analysis of species range data obtained from the Texas Parks and Wildlife Department and wind data obtained from the National Renewable Energy Laboratory. Results indicate one avian species, Tympanuchus pallidicinctus, is at high risk for wind development interaction on an annual basis, with 20 species of birds and nine species of bats at higher risk during …

Ischemic events of even a very short duration are not tolerated Ill in humans. The human cost of ischemia, when looked at as combined cardiovascular disease, dwarfs all other causes of death in the United States. Annually, CVD kills as many people in the US as does cancer, chronic lower respiratory disease, accidents, and diabetes mellitus combined. In 2005 (the latest year for which final statistics are available), CVD was responsible for 864,480 deaths or 35.3 percent of total deaths for the year. In my study, I have used the nematode Caenorhabditis elegans to determine genetic and environmental modulators of oxygen deprivation a key component of ischemia. I have found that animals with mutations in insulin like signaling pathways, neuronal function, electron transport chain components, germline function, and animals that are preconditioned by being raised on a diet of E. coli HT115 bacteria at 25°C have an enhanced ability to survive long-term (>72 hours) anoxia (<.005 kPa O2) at 20°C. The enhanced anoxia survival phenotype partially correlates with increased levels of carbohydrate stores in the nematodes. Suppression of this enhanced anoxia survival phenotype is possible by altering expression of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, the FOXO transcription factor DAF-16, and …

Northern bobwhite populations have declined concurrent with global warming. The focal period of this study was the 12-d pre-incubation period, when bobwhite eggs remain in the nest without the thermal protection of the incubating parent. This study first established the storage and thermal limits of bobwhite eggs, then investigated how global warming may impact oviparous embryos and how bobwhite embryos react to acute and chronic doses of simulated drought temperatures during pre-incubation. First, the maximum storage limit of bobwhite eggs was determined by storing eggs &#8804;21 d and measuring hatching success and pH of egg albumen and yolk. Hatching success of stored eggs declined after 14 d, when yolk and albumen pH reached levels detrimental to embryonic development. Secondly, thermal limits were determined by exposing bobwhite eggs to hyperthermic temperatures (38-52 °C). Bobwhite embryos survived 50 °C for 1 h, 49 °C for 3 h and 46 °C for 6 h. Results indicate an adaptation to the naturally occurring temperature extremes that can occur in the bobwhite's southern range during pre-incubation. Subsequently, bobwhite eggs were exposed to either low constant (LC), low fluctuating (LF), high constant (HC), or high fluctuating (HF) temperatures during pre-incubation to determine if the nature of …

N-acyl ethanolamines (NAEs) are a class of lipids recently recognized as signaling molecules which are controlled, in part, by their degradation by fatty acid amide hydrolase (FAAH). On the basis of previous studies indicating increased NAE levels in a tobacco cell suspension-xylanase elicitor exposure system and the availability of FAAH mutants, overexpressor and knockout (OE and KO) genotypes in Arabidopsis thaliana, further roles of NAEs in A. thaliana plant defense was investigated. The commonly occurring urban antimicrobial contaminant triclosan (TCS) has been shown to suppress lipid signaling associated with plant defense responses. Thus, a second objective of this study was to determine if TCS exposure specifically interferes with NAE levels. No changes in steady state NAE profiles in A. thaliana-Pseudomonas syringae pv. syringae and A. thaliana-flagellin (bacterial peptide, flg22) challenge systems were seen despite evidence that defense responses were activated in these systems. There was a significant drop in enoyl-ACP reductase (ENR) enzyme activity, which catalyzes the last step in the fatty acid biosynthesis pathway in plants, on exposure of the seedlings to TCS at 10 ppm for 24 h and decreased reactive oxygen species (ROS) production due to flg22 in long term exposure of 0.1 ppm and short term …

The question of post-mortem interval (PMI) or time since death is often the most sought after piece of information associated with a medical death investigation. Based on the observation that DNA degradation disproportionately affects the analysis of larger genetic loci, it was proposed that DNA degradation, as a result of autolysis or putrefaction, could prove suitable as a potential rate-of-change indicator of PMI. Nine randomly amplified polymorphic DNA (RAPD) analysis primers and three sets of directed amplification primers were evaluated to determine their suitability for use in assessing the degree of DNA fragmentation in tissue samples. They were assessed for amplicon specificity, total DNA target sensitivity, allele monomorphism and the observance of degradation-based profile changes. Markers meeting the requisite criteria were then used to assess a range samples degraded under controlled and uncontrolled conditions. Tissue samples collected from seven domestic pigs (Sus scrofa) were incubated under controlled laboratory or uncontrolled field conditions to produce samples simulating those potentially collected in a forensic case. DNA samples isolated from these specimens were then analyzed at those loci which had been determined to meet the requisite criteria. Collectively, data generated from these analyses indicate that genetic profiles generated by this approach can provide …