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 Department: Department of Biological Sciences
Aging Is a Determinant in Anoxia Stress Tolerance in Caenorhabditis Elegans

Aging Is a Determinant in Anoxia Stress Tolerance in Caenorhabditis Elegans

Date: May 2013
Creator: Goy, Jo M.
Description: Oxygen availability is critical for survival for most organisms. The nematode, C. elegans, has been useful for studying genetic regulation of anoxia tolerance due to the oxygen deprivation response mechanisms shared with other metazoans. Studies examining long-term anoxia (72h, LTA) tolerance have only been conducted at adult day 1. To investigate the effect of aging on anoxia tolerance wild-type and mutant strains were exposed to LTA between adult day 1 and day 9. Wild-type isolates and daf-16(mu86) (FOXO transcription factor regulated by insulin-signaling) and aak-2(gt33) (catalytic subunit of AMP-activated protein kinase) strains were anoxia sensitive at day 1 and displayed increased LTA tolerance with aging correlated with reproductive senescence followed by a decline in survivorhsip through day 9. The daf-2(e1370) (insulin receptor homologue of C. elegans), glp-1(e2141) (a lin-12/Notch receptor) and fog-2(q71) (required for spermatogenesis) strains were LTA-tolerant through day 5. I conclude that aging influences LTA-tolerance in a strain- and age-dependent manner. In addition to being LTA-tolerant the daf-2(e1370) and glp-1(e2141) strains have a longevity phenotype that is suppressed by loss of kri-1 or daf-12. While loss of kri-1 did not suppress the LTA-tolerant phenotype of glp-1(e2141) at day 1 the portion of impaired survivors increased at day 3 ...
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Bioconcentration and Morphological Effects of Triclosan on Three Species of Wetland Plants

Bioconcentration and Morphological Effects of Triclosan on Three Species of Wetland Plants

Date: May 2013
Creator: Smith, Caleb M.
Description: Triclosan (TCS) is an antimicrobial compound found in several types of common household products. After being washed down the drain, TCS will then end up in the local watershed. Although numerous studies have been conducted to evaluate the fate and effects of TCS in aquatic environments, there have been no studies evaluating the role arbuscular mycorrhizal fungi (AM) play in a plants response to TCS exposure. Three species of wetland plants native North Texas were inoculated with AM spores and exposed to 0, 0.4 g/L and 4.0 g/L TCS concentrations. Root morphology of E. prostrata and S. herbacea showed AM and exposure responses. S. herbacea produced the greatest amounts biomass and TCS bioaccumulation, in all but one treatment. It also displayed opposing results to E. prostrata in measures of root length, root surface area, relative root mass, relative shoot mass and shoot:root ratio. TCS root tissue concentrations increased with increased exposures for both E. prostrata and S. herbacea. Even though E. prostrata had the lowest levels in each measure of biomass production, it had the highest amount of root TCS bioaccumulation in the AM inoculated 4.0 g/L treatment. H. laevis was between the other two species in terms of biomass ...
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Evaluating the Habitat Requirements of the Golden Orb Mussel (Quadrula Aurea) for Conservation Purposes

Evaluating the Habitat Requirements of the Golden Orb Mussel (Quadrula Aurea) for Conservation Purposes

Date: May 2013
Creator: Hammontree, Sarah
Description: Many freshwater mussels are imperiled, due to a number of interrelated factors such as habitat alteration, degradation of water quality, and impoundments. The Golden Orb mussel (Quadrula aurea, I. Lea, 1859) is endemic to the state of Texas and is currently a candidate for the endangered species list, as the number of known populations has been declining in recent years. Little is currently known about Q. aurea aside from basic distribution data. This study is focused on evaluating a combination of macro-habitat and micro-habitat variables to determine their influence on the distribution and density of this species. Macro-habitat variables, including dominant land cover, surface geology, and soil erodibility factor, did not have a significant relationship with mussel distributions. The best model of micro-habitat variables that impacts the Q. aurea distributions is comprised of relative substrate stability (RSS) at moderate flows and current velocity at low flows. For all mussel species in this study, current velocity at low flows is the primary variable that influences distribution. Q. aurea are associated with habitats where larger sediment particles (large gravel and cobble) help to stabilize the substrate in areas with higher current velocities. An understanding of the preferred habitats for Q. aurea can ...
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Examination of the Relationship Between Glucuronic Acid and Vascular Damage in Rats

Examination of the Relationship Between Glucuronic Acid and Vascular Damage in Rats

Date: May 2013
Creator: Moore, Ryan
Description: The goal of this experiment was to examine the role of glucuronic acid in the development of vascular damage in the kidneys and retinas of diabetic individuals. Glucuronic acid was provided to rats in their water at various concentrations in order to increase plasma levels of the compound. Kidneys and retinas were excised and compared to control specimens using microscopy to determine the effect of elevated blood glucuronic acid levels on the occurrence of microaneurysms in renal capillary networks. No differences were seen between the treatment and control groups. Further study needs to be conducted to determine a more suitable time frame for this experiment.
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Exploring the Evolutionary History of North American Prairie Grouse (Genus: Tympanuchus) Using Multi-locus Coalescent Analyses

Exploring the Evolutionary History of North American Prairie Grouse (Genus: Tympanuchus) Using Multi-locus Coalescent Analyses

Date: May 2013
Creator: Galla, Stephanie J.
Description: Conservation biologists are increasingly using phylogenetics as a tool to understand evolutionary relationships and taxonomic classification. The taxonomy of North American prairie grouse (sharp-tailed grouse, T. phasianellus; lesser prairie-chicken, T. pallidicinctus; greater prairie-chicken, T. cupido; including multiple subspecies) has been designated based on physical characteristics, geography, and behavior. However, previous studies have been inconclusive in determining the evolutionary history of prairie grouse based on genetic data. Therefore, additional research investigating the evolutionary history of prairie grouse is warranted. In this study, ten loci (including mitochondrial, autosomal, and Z-linked markers) were sequenced across multiple populations of prairie grouse, and both traditional and coalescent-based phylogenetic analyses were used to address the evolutionary history of this genus. Results from this study indicate that North American prairie grouse diverged in the last 200,000 years, with species-level taxa forming well-supported monophyletic clades in species tree analyses. With these results, managers of the critically endangered Attwater's prairie-chicken (T. c. attwateri) can better evaluate whether outcrossing Attwater's with greater prairie-chickens would be a viable management tool for Attwater's conservation.
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Expression of G-protein Coupled Receptors in Young and Mature Thrombocytes and Knockdown of Gpr18 in Zebrafish

Expression of G-protein Coupled Receptors in Young and Mature Thrombocytes and Knockdown of Gpr18 in Zebrafish

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Date: May 2013
Creator: Potbhare, Vrinda Nikhil
Description: In this study, a novel method based on biotinylated antibodies and streptavidin coated magnetic beads was used to separate the thrombocyte subpopulations from zebrafish whole blood. DiI-C18, a lipophilic dye, labels only young thrombocytes when used at low concentrations. Commercially available biotinylated anti-Cy3 antibody was used to label the chromophore of DiI-C18 on the young thrombocytes and streptavidin coated magnetic beads were added subsequently, to separate young thrombocytes. The remaining blood cells were probed with custom-made biotinylated anti-GPIIb antibody and streptavidin magnetic beads to separate them from other cells. Further, thrombocytes are equivalents of mammalian platelets. Platelets play a crucial role in thrombus formation. The G-protein coupled receptors (GPCRs) present on the platelet surface are involved during platelet activation and aggregation processes. So, thrombocytes were studied for the presence of GPCRs. The GPCR mRNA transcripts expressed in the young and mature thrombocytes were subjected to densitometry analysis and pixel intensities of the bands were compared using one way ANOVA. This analysis did not show significant differences between the young and mature GPCR mRNA transcripts but identified a novel GPCR, GPR18 that was not reported in platelets earlier. To study the function of this GPCR, it was knocked down using GPR18 ...
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Novel Role of Trypsin in Zebrafish

Novel Role of Trypsin in Zebrafish

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Date: May 2013
Creator: Alsrhani, Abdullah Falleh
Description: It has been shown previously in our laboratory that zebrafish produce trypsin from their gills when they are under stress, and this trypsin is involved in thrombocyte activation via PAR2 during gill bleeding. In this study, I investigated another role of the trypsin that is secreted from zebrafish. This investigation has demonstrated a novel role of trypsin in zebrafish. Not only did this investigation demonstrate the role of trypsin in zebrafish behavior, but also it showed that PAR2 might be the receptor that is involved in trypsin-mediated behavioral response. In addition, we have shown that Gq and ERK inhibitors are able to block the trypsin pathway and prevent the escaping behavior. Finally, the results of this investigation suggest that the cells that respond to trypsin are surface cells, which have an appearance similar to that of neuromast cells.
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Primary Cilia in the Oligodendrocyte Lineage

Primary Cilia in the Oligodendrocyte Lineage

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Date: May 2013
Creator: Hao, Yung-Chia
Description: oligodendrocytes migrate from the corpus callosum into the overlying cortex. The incidence of cilia did not change markedly across age groups, and did not vary consistently with the number of processes per cell, which was used as an indication of the maturation stage of OPCs and young OLs. The mean percent of Olig1 immunopositive (Olig1+) cells having cilia across ages was 33.1% + 16.5%, with all ages combined. In O4+ cells of these mice, 56.7 + 3.6% had primary cilia. If it is the case that adult OLs do not have cilia, the point in the lineage when primary cilia are lost is still unknown. Adult mice that had been injected with cyclopamine to block cilia-dependent Shh signaling were examined to determine whether the rate of generating new OPCs was influenced. In the CC of control mice, the numerical density of Olig1+/BrdU+ cells was 1.29 + 0.07/mm2 was reduced to 0.68 + 0.38/mm2 in the cyclopamine-injected group, and the numerical density of all BrdU+ cells (including both Olig1+ and Olig1- cells) of 4.55 + 1.50/mm2 in the control group was reduced to 3.14 + 1.27/mm2 in the cyclopamine-injected group. However, there were only 2 mice in each group and the ...
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Beta-adrenergic Blockade Via Atenolol and Its Effects on Blood Pressure, Heart Rate, and Renal Morphology in the Developing Chicken Gallus Gallus Domesticus

Beta-adrenergic Blockade Via Atenolol and Its Effects on Blood Pressure, Heart Rate, and Renal Morphology in the Developing Chicken Gallus Gallus Domesticus

Date: December 2012
Creator: Rossitto Lopez, Josie Jovita
Description: Chicken embryos were chronically exposed to the ?1- blocker atenolol during one of three stages: mesonephros (E7-E9), mesonephros-metanephros (E11-E13), or metanephros (E15-E17). Mesonephros group hearts were larger than all other groups (P < 0.01). Mesonephros and metanephros group kidneys were larger than all remaining groups (P < 0.0001). The mesonephros group nephron number was ~40% lower than control values (P = 0.002). Glomerular areas were 26% and 18% larger than the control group in the mesonephros and metanephros groups, respectively (P < 0.001). These data suggest an E7-E9 critical window of cardiovascular and renal development for atenolol. Acute atenolol exposure in E15 embryos showed an increase in mean arterial pressure with all but the highest dose. All doses significantly decreased heart rate.
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Characterization of Arthrobacter Globiformis Aspartate Transcarbamylase Concentrations of Substrates

Characterization of Arthrobacter Globiformis Aspartate Transcarbamylase Concentrations of Substrates

Date: December 2012
Creator: Wright, Jackie
Description: This thesis consists of one major section with two subsections. The first subsection investigates the activity of Arthrobacter globiformis aspartate transcarbamylase's specific activity with increasing concentrations of the enzyme's substrate. Dihydroorotase (DHOase) activity was also measured with increasing concentrations of the substrate dihydroorotate. The second subsection collected data in order to classify the enzyme, resulting in a classification into the category of class A ATCases with bifunctional ATCase-DHOase complexes. The thesis provides evidence to broaden understanding of the ATCase and DHOase enzymes for members of the family that Arthrobacter belongs to.
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