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Cytochrome P450 Gene Expression Modulates Anoxia Sensitivity in Caenorhabditis Elegans

Description: With an increasing population suffering from obesity or Diabetes Mellitus (DM), it is more pertinent than ever to understand how physiological changes impact cellular processes. Patients with DM often suffer from obesity, hyperglycemia, altered fatty acids that contribute to vascular dysfunction, and increased risk to ischemia. Caenorhabditis elegans is a model system used to study the conserved insulin signaling pathway, cellular responses in whole organisms and the impact a glucose diet has on oxygen deprivation (anoxia) responses. RNA-sequencing (RNA-Seq) was used to analyze the expression of genes in the anoxia sensitive populations of N2 (wild-type) fed glucose and hyl-2(tm2031), a mutant with altered ceramide metabolism. Comparison of the altered transcripts in the anoxia sensitive populations revealed 199 common transcripts- 192 upregulated and 7 downregulated. One of the gene families that have altered expression in the anoxia sensitive populations encode for Cytochrome P450 (CYP). CYPs are located both in the mitochondria and endoplasmic reticulum (ER), but the CYPs of interest are all predicted to be mainly subcellularly localized to the ER. Here, I determined that knock-down of specific cyp genes, using RNA interference (RNAi), increased anoxia survival in N2 animals fed a standard diet. Anoxia sensitivity of the hyl-2(tm2031) animals was supressed by RNAi of cyp-25A1 or cyp-33C8 genes. These studies provide evidence that the CYP detoxification system impacts oxygen deprivation responses. using hsp-4::GFP animals, a transcriptional reporter for ER unfolded protein response (UPR), I further investigated the impact of cyp knock-down, glucose, and anoxia on ER UPR due to the prediction of CYP-33C8 localization to the ER. Glucose significantly increased ER UPR and cyp knock-down non-significantly increased ER UPR. Measurements of ER UPR due to anoxia were made difficult, but representative images show an increase in ER stress post 9-hour anoxia exposure. This study provides evidence that glucose affects ER ...
Date: August 2016
Creator: Quan, Daniel L
Partner: UNT Libraries

Glucose and Altered Ceramide Biosynthesis Impact the Transcriptome and the Lipidome of Caenorhabditis elegans

Description: The worldwide rise of diabetes and obesity has spurred research investigating the molecular mechanisms that mediate the deleterious effects associated with these diseases. Individuals with diabetes and/or obesity are at increased risk from a variety of health consequences, including heart attack, stroke and peripheral vascular disease; all of these complications have oxygen deprivation as the central component of their pathology. The nematode Caenorhabditis elegans has been established as a model system for understanding the genetic and molecular regulation of oxygen deprivation response, and in recent years methods have been developed to study the effects of excess glucose and altered lipid homeostasis. Using C. elegans, I investigated transcriptomic profiles of wild-type and hyl-2(tm2031) ( a ceramide biosynthesis mutant) animals fed a standard or a glucose supplemented diet. I then completed a pilot RNAi screen of differentially regulated genes and found that genes involved in the endobiotic detoxification pathway (ugt-63 and cyp-25A1) modulate anoxia response. I then used a lipidomic approach to determine whether glucose feeding or mutations in the ceramide biosynthesis pathway or the insulin-like signaling pathway impact lipid profiles. I found that gluocose alters the lipid profile of daf-2(e1370) (an insulin-like receptor mutant) animals. These studies indicate that a transcriptomic approach can be used to discover novel pathways involved in oxygen deprivation response and further validate C. elegans as a model for understanding diabetes and obesity.
Date: August 2016
Creator: Ladage, Mary Lee
Partner: UNT Libraries

Identification of a Potential Factor Affecting Graduation Rates in STEM for Hispanic Students at the University of North Texas, via Analysis of Nonfiction Science Books in Spanish Language for ELLs in the Dallas ISD Schools

Description: Latinos are the largest minority group in the U.S.; however despite the continuous growth of the Hispanic population, Latinos are severely underrepresented in STEM fields. One of the reasons that might explain why Latinos do not major in STEM is the way they encounter science curriculum in primary school. Students' limited proficiency in English may constrain their science achievement when instruction is delivered exclusively in English. A quantitative analysis with graduation rates in STEM from 2009 to 2014 at the University of North Texas was conducted, finding that there is a significant difference (p<0.05) in the number of bachelor's degrees in STEM between Hispanic, White, African American and other student populations. Interviews with teachers, librarians and publishing companies were performed to describe the limited science literature in Spanish at the Dallas ISD schools. Improving science literacy by teaching according to ELLs' linguistic skills and culture may lead to a better understanding of science curriculum throughout their education, which may translate into higher college graduation rates by Hispanic recipients in STEM.
Date: August 2016
Creator: Garcia Colin, Monica
Partner: UNT Libraries

Influence of a Human Lipodystrophy Gene Homologue on Neutral Lipid Accumulation in Arabidopsis Leaves

Description: CGI-58 is the defective gene in the human neutral lipid storage disease called Chanarin-Dorfman syndrome. This disorder causes intracellular lipid droplets to accumulate in nonadipose tissues, such as skin and blood cells. Here, disruption of the homologous CGI-58 gene in Arabidopsis thaliana resulted in the accumulation of neutral lipid droplets in mature leaves. Mass spectroscopy of isolated lipid droplets from cgi-58 loss-of-function mutants showed they contain triacylglycerols with common leaf specific fatty acids. Leaves of mature cgi-58 plants exhibited a marked increase in absolute triacylglycerol levels, more than 10-fold higher than in wild-type plants. Lipid levels in the oil-storing seeds of cgi-58 loss-of-function plants were unchanged, and unlike mutations in beta-oxidation, the cgi-58 seeds germinated and grew normally, requiring no rescue with sucrose. We conclude that the participation of CGI-58 in neutral lipid homeostasis of nonfat-storing tissues is similar, although not identical, between plant and animal species. This unique insight may have implications for designing a new generation of technologies that enhance the neutral lipid content and composition of corp plants.
Date: August 2016
Creator: James, Christopher Neal
Partner: UNT Libraries

Maturation of Endothermic Capacity within the Avian Developmental Spectrum: A Characterization of Thermoregulatory Metamorphosis

Description: An avian embryo is ectothermic, with body temperature determined by environmental temperature. Upon hatching, the neonate begins a conversion so that endothermic capacity becomes feasible and body temperature becomes independent of environment. Whole animal metabolic rate and ventilation response, cardiovascular development, and maturation of muscle mitochondrial flux were the focus of this dissertation because of the direct role in shivering thermogenesis. Precocial ducks and altricial Double-crested Cormorants exhibit increasing hematocrit and disproportionate increases in fractional heart mass resulting in greater oxygen delivery capacity and increased capacity of muscles to utilize oxygen compared with ectothermic American Alligator and Common Snapping turtles. By selecting for faster growth and higher meat yield in the domestic chicken, differences in whole-animal, tissue, cellular, and regulatory responses are evident between broiler and layer type birds. In the altricial red-winged blackbird, despite appearance of a whole animal endothermic response sometime after 7 dph, capacity of skeletal muscles involved in shivering thermogenesis peaks prior to that time. Thus, full development of endothermy is delayed in this species, allowing the altricial nestling to allocate energy towards growth rather than metabolic maintenance. Hypothyroidism in neonate red-winged blackbirds results in delayed maturation of the cardiovascular system and mitochondrial oxidative capacity of skeletal muscle. Such deficiencies were quickly recovered once the animals returned to a normothyroid state, apparently at the cost of increasing body mass. Insights into onset of thermoregulation provide a more thorough understanding of metabolic and physical transitions a hatchling bird must undergo to reach the adult endothermic phenotype. Endothermic capacity will continue to be at the forefront of physiological research because of the significance of changes between the energetic relations of an animal that must occur with its environment.
Date: August 2016
Creator: Sirsat, Sarah Goy
Partner: UNT Libraries

Presence of Wolbachia, A Potential Biocontrol Agent: Screening for Vertebrate Blood Meal Source and West Nile Virus in Mosquitoes in the North Texas Region

Description: West Nile virus (WNV) is a geographically endemic mosquito-borne flavivirus that has spread across the United States infecting birds, mosquitos, humans, horses and other mammals. The wide spread nature of this virus is due to the ability of the mosquito vector to persist in broad, ecological diverse environments across the United States. In this study, mosquito populations in North Texas region were sampled for detection of Wolbachia, blood meal source, and WNV. The ultimate goal of this study was to examine the potential of a biocontrol agent, Wolbachia sp. that colonizes the hindgut of various insects, including mosquitos, as a natural means to interrupt virus transmission from mosquitos to other hosts, including humans. In Australia, Wolbachia sp. from fruit flies (Drosophila melanogaster) have been successfully used to block transmission of a similar pathogenic virus from mosquitos responsible for transmission of Dengue fever. Here, mosquitoes were collected using CDC style Gravid Traps in Denton, Texas, from October 2012 through September 2014. Collected mosquitoes were identified, sexed, and categorized as to the amount of host blood in their alimentary system using a Zeiss Axio Zoom microscope (Carl Zeiss Microscopy, LLC, Thornwood, NY). Culex quinquefaciatus was the dominant blood engorged species collected. Smaller populations of Culex tarsalis and Aedes albopictus, another known vector for WNV were also collected. Mosquito larva were also collected from the UNT water research field station and reared to adults. Cx. tarsalis was the dominant mosquito taken from this habitat. Samples of Cx. quinquefasciatus, Cx. tarsalis and A. albopictus were analyzed for Wolbachia sp. and to identify host blood in the mosquito alimentary system. Total DNA extraction from the pool of mosquito samples was by both commercially available DNA extraction kits (Qiagen, Valencia, CA) and salt extraction technique. Polymerase chain reaction (PCR) was used to amplify and identify Wolbachia ...
Date: August 2016
Creator: Adiji, Olubu Adeoye
Partner: UNT Libraries

Residential Grid-Connected Photovoltaics Adoption in North Central Texas: Lessons from the Solarize Plano Project

Description: Residential Grid-Connected Photovoltaics (GPV) systems hold remarkable promise in their potential to reduce energy use, air pollution, greenhouse gas emissions, and energy costs to consumers, while also providing grid efficiency and demand-side management benefits to utilities. Broader adoption of customer-sited GPV also has the potential to transform the traditional model of electricity generation and delivery. Interest and activity has grown in recent years to promote GPV in north central Texas. This study employs a mixed methods design to better understand the status of residential GPV adoption in the DFW area, and those factors influencing a homeowner's decision of whether or not to install a system. Basic metrics are summarized, including installation numbers, distribution and socio-demographic information for the case study city of Plano, the DFW region, Texas, and the United States. Qualitative interview methods are used to gain an in-depth understanding of the factors influencing adoption for the Solarize Plano case study participants; to evaluate the effectiveness of the Solarize Plano program; and to identify concepts that may be regionally relevant. Recommendations are presented for additional research that may advance GPV adoption in north central Texas.
Date: August 2016
Creator: Jack, Katherine G.
Partner: UNT Libraries

Respiratory Responses in the Freshwater Snail (Pomacea Bridgesii) are Differently Affected by Temperature , Body Mass,and Oxygen Avalability

Description: Pomacea bridgesii is a snail species native to tropical and sub-tropical regions, where it usually faces variability in water, temperature and oxygen level. This study of the effect of temperature on mass-specific oxygen consumption (ṀO2) and its relation to body weight shows that the ṀO2 of juvenile snails in normoxia (18-21 kPa) acclimated at temperature of 25°C ranged from 5 to 58 µMol O2/g/h, with a mean of 41.4 ± 18.3 µMol O2/g/h (n=7). Adult snails in normoxia at 25°C show less variation, ranging from 13 to 23 µMol O2/g/h , with a mean of 24.4± 6.1 µMol O2/g/h (n=12). The Q10 value for juvenile snails was higher in the interval 25-30°C (Q 10=5.74) than in the interval 20-25°C (Q10= 0.286). In adult snails, Q10 was higher in the interval 20-25°C (Q10=3.19). ṀO2 of P. bridgesii in relation to body weight showed a negative linear correlation between metabolic rate and body weight with b values between 0.23 and 0.76. Also, both juvenile and adult snails exhibited weak O2 regulation. In general, the different respiratory characteristics between juvenile and adult snails might be related to the differences of individual life history, which caused them to perform differently in face of temperatures change. Additionally, Pomacean snails species originated in tropical habitats where there is a lack of thermal fluctuation. For this reason, Pomacean snails may be less likely to have evolved effective thermal acclimation capabilities.
Date: August 2016
Creator: Frifer, Wenasa Salem
Partner: UNT Libraries

Biodiversity and Genetic Structure of Benthic Macroinvertebrates along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile

Description: Altitudinal gradients in Sub-Antarctic freshwater systems present unique opportunities to study the effect of distinct environmental gradients on benthic macroinvertebrate community composition and dispersal. This study investigates patterns in biodiversity, dispersal and population genetic structure of benthic macroinvertebrate fauna across an altitudinal gradient between two watersheds on Navarino Island in southern Chile. Patterns in diversity, density, evenness and functional feeding groups were not significantly different across the altitudinal gradient in both the Windhond and Róbalo Rivers. Taxa richness in both rivers generally increased from the headwaters of the river to the mouth, and functional feeding group patterns were consistent with the predictions of the River Continuum Concept. Population genetic structure and gene flow was investigated by sampling the mitochondrial cytochrome oxidase I gene in two invertebrate species with different dispersal strategies. Hyalella simplex (Amphipoda) is an obligate aquatic species, and Meridialaris chiloeense (Ephemeroptera) is an aquatic larvae and a terrestrial winged adult. Contrasting patterns of population genetic structure were observed. Results for Hyalella simplex indicate significant differentiation in genetic structure in the Amphipod populations between watersheds and lower genetic diversity in the Róbalo River samples, which may be a result of instream dispersal barriers. Meridialaris chiloeense exhibited weak population structure but higher genetic diversity, which suggests this species is able to disperse widely as a winged adult.
Date: May 2016
Creator: Pulliam, Lauren
Partner: UNT Libraries

The Effects of Neonicotinoid Exposure on Embryonic Development and Organ Mass in Northern Bobwhite Quail

Description: Since their emergence in the early 1990s, neonicotinoid use has increased exponentially to make them the world's most prevalent insecticides. Although there is considerable research concerning the lethality of neonicotinoids, their sub-lethal and developmental effects are still being explored, especially with regards to non-mammalian species. The goal of this research was to investigate the effects of the neonicotinoid imidacloprid on the morphological and physiological development of northern bobwhite quail (Colinus virginianus). Bobwhite eggs (n = 650) were injected with imidacloprid concentrations of 0 (sham), 10, 50, 100 and 150 grams per kilogram of egg mass, which was administered at day 0 (pre-incubation), 3, 6, 9, or 12 of growth. Embryos were dissected on day 19 when they were weighed, staged, and examined for any overt structural deformities. Embryonic heart, liver, lungs and kidneys were also weighed and preserved for future use. Treated embryos exhibited increased frequency of severely deformed beaks and legs, as well as larger hearts and smaller lungs at the higher dosing concentrations. Some impacts are more pronounced in specific dosing periods, implying that there may be critical windows of development when embryos are highly susceptible to neonicotinoid exposure. This investigation suggests that imidacloprid could play a significant role in chick survival and declining quail populations in treated regions of the country.
Date: May 2016
Creator: Gobeli, Amanda
Partner: UNT Libraries

Genetic Characterization of Central and South American Populations of Scarlet Macaw (Ara macao)

Description: The wild populations of the Scarlet Macaw subspecies native to southern Mexico and Central America, A. m. cyanoptera, have been drastically reduced over the last half century and are now a major concern to local governments and conservation groups. Programs to rebuild these local populations using captive bred specimens must be careful to reintroduce the native A. m. cyanoptera, as opposed to the South American nominate subspecies (A. m. macao) or hybrids of the two subspecies. Molecular markers for comparative genomic analyses are needed for definitive differentiation. Here I describe the isolation and sequence analysis of multiple loci from 7 pedigreed A. m. macao and 14 pedigreed A. m. cyanoptera specimens. The loci analyzed include the 18S rDNA genes, the complete mitogenome as well as intronic regions of selected autosomally-encoded genes. Although the multicopy18S gene sequences exhibited 10% polymorphism within all A. macao genomes, no differences were observed between any of the 21 birds whose genomes were studied. In contrast, numerous polymorphic sites were observed throughout the 16,993 bp mitochondrial genomes of both subspecies. Although much of the polymorphism was observed in the genomes of both subspecies, subspecies-specific alleles were observed at a number of mitochondrial loci, including 12S, 16S, CO2 and ND3. Evidence of possible subspecies-specific alleles were also found in three of four screened nuclear loci. Collectively, these mitochondrial and nuclear loci can be used as the basis to distinguish A. m. cyanoptera from the nominate subspecies, A. m. macao, as well as identify many hybrids, and most importantly will contribute to further reintroduction efforts.
Date: May 2016
Creator: Kim, Tracy
Partner: UNT Libraries

The Influence of Urban Green Spaces on Declining Bumble Bees (Hymenoptera: Apidae)

Description: Bumble bees (Bombus spp.) are adept pollinators of countless cultivated and wild flowering plants, but many species have experienced declines in recent decades. Though urban sprawl has been implicated as a driving force of such losses, urban green spaces hold the potential to serve as habitat islands for bumble bees. As human populations continue to grow and metropolitan areas become larger, the survival of many bumble bee species will hinge on the identification and implementation of appropriate conservation measures at regional and finer scales. North Texas is home to some the fastest-growing urban areas in the country, including Denton County, as well as at least two declining bumble bee species (B. pensylvanicus and B. fraternus). Using a combination of field , molevular DNA and GIS methods I evaluated the persistence of historic bumble bee species in Denton County, and investigated the genetic structure and connectivity of the populations in these spaces. Field sampling resulted in the discovery of both B. pensylvanicus and B. fraternus in Denton County's urban green spaces. While the relative abundance of B. fraternus in these spaces was significantly lower than historic levels gleaned from museum recors, that of B. pensylvanicus was significantly higher. Statistical analyses found that both bare ground and tree cover surrounding sample sites were negatively associated with numbers of bumble bee individuals and hives detected in these green spaces. Additionally, limited genetic structuring of bumble bee populations was detected, leading to the conclusion that extensive gene flow is occurring across populations in Denton County.
Date: May 2016
Creator: Beckham, Jessica Lorene
Partner: UNT Libraries

Informing Conservation Management Using Genetic Approaches: Greater Sage-grouse and Galápagos Short-eared Owls as Case Studies

Description: Small isolated populations are of particular conservation interest due to their increased extinction risk. This dissertation investigates two small wild bird populations using genetic approaches to inform their conservation. Specifically, one case study investigated a Greater Sage-grouse (Centrocercus urophasianus) population located in northwest Wyoming near Jackson Hole and Grand Teton National Park. Microsatellite data showed that the Jackson sage-grouse population possessed significantly reduced levels of neutral genetic diversity and was isolated from other Wyoming populations. Analysis with single nucleotide polymorphisms (SNPs) and microsatellite data provided further evidence that the population's timing of isolation was relatively recent and most likely due to recent anthropogenic habitat changes. Conservation recommendations include maintaining or increasing the population's current size and reestablishing gene flow with the nearest large population. The second case study investigated the genetic distinctiveness of the Floreana island population of the Galápagos Short-eared Owl (Asio flammeus galapagoensis). Mitochondrial DNA sequence data did not detect differences across nine island populations, yet microsatellite and morphometric data indicated that limited gene flow existed with the population and surrounding island populations, which appeared asymmetric in direction from Floreana to Santa Cruz with no indication of gene flow into Floreana. These results have important conservation implications and recommend that the Floreana Short-eared Owl population be held in captivity during the rodenticide application planned for an ecosystem restoration project in 2018. The population is less likely to receive immigrants from surrounding island populations if negatively effected by feeding on poisoned rodents.
Date: May 2016
Creator: Schulwitz, Sarah E
Partner: UNT Libraries

The Effect of Post-exercise Ethanol Consumption on the Acute Hormonal Response to Heavy Resistance Exercise in Women

Description: The purpose of this study was to examine the hormonal response to acute ethanol ingestion following a bout of heavy resistance exercise in women. Eight resistance trained women completed two identical acute heavy resistance exercise tasks (AHRET). From 10-20 minutes post-AHRET, participants consumed either a grain ethanol or a placebo beverage. Blood was collected before (PRE) and immediately after the AHRET (IP) and then every 20 minutes for five hours. Blood collected after beverage ingestion was pooled into 3 batches (phases: 20-40 minutes, 60-120 minutes, and 140-300 minutes post-exercise) and analyzed for serum total testosterone (TT), free testosterone (FT), insulin-like growth factor-I (IGF-I), human growth hormone (GH), cortisol (COR), and estradiol (E2) concentrations. Circulating concentrations of TT were significantly greater at P20-40 than at PRE, P60-120, and P140-300. Circulating concentrations of FT were significantly greater at P20-40 than at all other times. Circulating concentrations of GH were significantly greater at IP than at PRE, P60-120, and P140-300. Circulating concentrations of COR were significantly greater at P20-40 than at all other times. Additionally, COR concentrations at P140-300 were significantly lower than at all other times. Circulating concentrations of IGF-1 were significantly greater at P20-40 than at P60-120 and P140-300. Circulating concentrations of E2 were significantly greater at P20-40 than at all other times. In summary, the present study demonstrated an acute modulation of the neuroendocrine milieu following a heavy resistance exercise bout in women. Ethanol ingestion appeared to have no significant effect on the characteristics of acute hormonal augmentation in TT, FT, GH, COR, IGF-1, or E2.
Date: December 2015
Creator: Budnar, Jr., Ronald G.
Partner: UNT Libraries

Environmental Modulation of the Onset of Air-breathing of the Siamese Fighting Fish and the Blue Gourami

Description: This study determined the effect of hypoxia on air-breathing onset and physiological and morphological characters in larvae of the air breathing fishes Trichopodus trichopterus and Betta splendens. Larvae were exposed intermittently (12/12 h daily) to 20, 17, and 14 kPa of PO2 from 1 to 40 days post-fertilization. Survival, onset of air breathing, wet body mass, O2, Pcrit were measured every 5 dpf. Hypoxia advanced by 4 days, and delayed by 9 days, the onset of air breathing in Betta and Trichopodus, respectively. Hypoxia increased larval body length, wet mass, and labyrinth organ respiratory surface of Betta, but did not affect these factors in Trichopodus. Hypoxic exposure increased O2 by 50-100% at each day throughout larval development in Betta, but had no effect on larval Trichopodus. Hypoxia decreased Pcrit in Betta by 37%, but increased Pcrit in Trichopodus by 70%. Larval Betta reared in hypoxia showed a modified heart rate:opercular rate ratio (3:1 to 2:1), but these changes did not occur in Trichopodus. Compared to Betta, the blood of Trichopodus had a higher P50 and much smaller Bohr and Root effects. These interspecific differences are likely due to ecophysiological differences: Betta is a non- obligatory air-breather after 36 dpf with a slow lifestyle reflected in its low metabolism, while Trichopodus is an obligatory air-breather past 32 dpf with an athletic fast lifestyle and accompanying high metabolism.
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Date: December 2015
Creator: Mendez Sanchez, Jose Fernando
Partner: UNT Libraries

Identification and Characterization of an Arabidopsis Thaliana Mutant with Tolerance to N-lauroylethanolamime

Description: N-Acylethanolamines (NAEs) are fatty acid derivatives in plants that negatively influence seedling growth. N-Lauroylethanolamine (NAE 12:0), one type of NAE, inhibits root length, increases radial swelling of root tips and reduces root hair numbers in a dose dependent manner in Arabidopis thaliana L. (ecotype Columbia). A forward genetics approach was employed by screening a population of T-DNA “activation-tagged” developed by the Salk Institute lines for NAE resistance to identify potential genes involved in NAE signaling events in Arabidopsis thaliana L. (ecotype Columbia). Seeds of the activation tagged lines were grown at 0, 25, 30, 50, 75 and 100 µM N-lauroylethanolamime (NAE 12:0). Ten plants which displayed NAE tolerance (NRA) seedling phenotypes, compared with wildtype (Columbia, Col-0) seedlings were identified. I focused on one mutant line, identified as NRA 25, where the tolerance to NAE 12:0 appears to be mediated by a single dominant, nuclear gene. Thermal asymmetric interlaced (TAIL) PCR identified the location of the T-DNA insert as 3.86 kbp upstream of the locus At1g68510. Quantitative PCR indicated that the transcript level corresponding to At1g68510 is upregulated approximately 20 fold in the mutant relative to wildtype. To determine whether the NAE tolerance in NRA 25 is associated with overexpression of At1g68510 I created overexpressing lines of At1g68510 with and without GFP fusions behind the 2X35S CaMV promoter. As predicted, results with overexpressing lines of At1g68510 also exhibited enhanced resistance to NAE when compared with the wildtype. Confocal images of the fusion proteins suggest that GFP-At1g68510 is concentrated in the nucleus and this was confirmed by counterstaining with 4', 6-Diamidino-2-phenylindol (DAPI). Futhermore, At1g68510 overexpressing lines and NRA 25 line also exhibited tolerance to abscisic acid (ABA) during seedling germination. The findings suggests that At1g68510 overexpression mediates seedling tolerance to both ABA and NAE, a mechanism independent of fatty acid amide hydrolase ...
Date: December 2015
Creator: Adhikari, Bikash
Partner: UNT Libraries

Identification of Genes Involved in Flocculation by Whole Genome Sequencing of Thauera Aminoaromatica Strain Mz1t Floc-defective Mutants

Description: Thauera aminoaromatica MZ1T, a floc-forming bacterium isolated from an industrial activated sludge wastewater treatment plant, overproduces exopolysaccharide (EPS) leading to viscous bulking. This phenomenon results in poor sludge settling and dewatering during the clarification process. To identify genes responsible for bacterial flocculation, a whole genome phenotypic sequencing technique was applied. Genomic DNA of MZ1T flocculation-deficient mutants were subjected to massively parallel sequencing. The resultant high-quality reads were assembled and compared to the reference genome of the wild type genome. We identified nine nonsynonymous mutations and one nonsense mutation putatively involved in EPS biosynthesis. Complementation of the nonsense mutation located in an EPS deacetylase gene restored the flocculating phenotype. The FTIR spectra of EPS isolated from the wild-type showed reduced C=O peak of the N-acetyl group at 1665 cm-1 as compared to the spectra of MZ1T floc-deficient mutant EPS, suggesting that the WT EPS was partially deacetylated. Gene expression analysis also demonstrated the deacetylase gene transcript increased before flocculation occurred. The results suggest that the deacetylation of MZ1T EPS is crucial for flocculation. The information obtained from this study will be useful for preventing viscous bulking and wastewater treatment system failure, and may have potential applications in the biotechnology sector for the controlled removal of cells.
Date: December 2015
Creator: Prombutara, Pinidphon
Partner: UNT Libraries

Identification of Hox Genes Controlling Thrombopoiesis in Zebrafish

Description: Thrombocytes are functional equivalents of mammalian platelets and also possess megakaryocyte features. It has been shown earlier that hox genes play a role in megakaryocyte development. Our earlier microarray analysis showed five hox genes, hoxa10b, hoxb2a, hoxc5a, hoxc11b and hoxd3a, were upregulated in zebrafish thrombocytes. However, there is no comprehensive study of genome wide scan of all the hox genes playing a role in megakaryopoiesis. I first measured the expression levels of each of these hox genes in young and mature thrombocytes and observed that all the above hox genes except hoxc11b were expressed equally in both populations of thrombocytes. hoxc11b was expressed only in young thrombocytes and not in mature thrombocytes. The goals of my study were to comprehensively knockdown hox genes and identify the specific hox genes involved in the development of thrombocytes in zebrafish. However, the existing vivo-morpholino knockdown technology was not capable of performing such genome-wide knockdowns. Therefore, I developed a novel cost- effective knockdown method by designing an antisense oligonucleotides against the target mRNA and piggybacking with standard control morpholino to silence the gene of interest. Also, to perform knockdowns of the hox genes and test for the number of thrombocytes, the available techniques were both cumbersome or required breeding and production of fish where thrombocytes are GFP labeled. Therefore, I established a flow cytometry based method of counting the number of thrombocytes. I used mepacrine to fluorescently label the blood cells and used the white cell fraction. Standard antisense oligonucleotide designed to the central portion of each of the target hox mRNAs, was piggybacked by a control morpholino and intravenously injected into the adult zebrafish. The thrombocyte count was measured 48 hours post injection. In this study, I found that the knockdown of hoxc11b resulted in increased number of thrombocytes and knockdown of hoxa10b, ...
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Date: December 2015
Creator: Sundaramoorthi, Hemalatha
Partner: UNT Libraries

The Role of Cysteinyl Leukotriene Receptor 2 in Thrombocyte Aggregation

Description: Cysteinyl leukotriene receptor 2, a G-protein coupled receptor known to be expressed and functional on human platelets. However, it seems that upon ligand activation the cysteinyl leukotriene receptor 2 activates a variety of signaling pathways in multiple cell types among different species. Previously, a former laboratory member Vrinda Kulkarni found cysteinyl leukotriene receptor 2 to be expressed on the surface of adult zebrafish thrombocytes. In this work I studied the characteristics of aggregation in adult zebrafish thrombocytes with the knockdown of cysteinyl leukotriene receptor 2. I used a newly developed knockdown method to study the function of cysteinyl leukotriene receptor 2. Knockdown of the cysteinyl leukotriene was confirmed using RT-PCR results showed p=.001, reduced sell surface level of expression of the cysteinyl leukotriene receptor 2 results showed that p=.002. I found that the knockdown of cysteinyl leukotriene receptor 2 results in prothrombotic thrombocytes by using flow cytometry p=.0001.
Date: December 2015
Creator: Reyna, Julianna
Partner: UNT Libraries

Role of Gpr17 in Thrombocyte Aggregation in Adult Zebrafish

Description: GPR17, a uracil nucleotide cysteinyl leukotriene receptor, belongs to the GPCR (G protein coupled receptor) family. It has been shown recently that inhibiting this protein in the nervous system in mice can lead to blockage of oligodendrocyte maturation, which supports myelin repair. Interestingly, our laboratory found GPR17 in thrombocytes. However, we do not know whether it has any function in thrombocyte aggregation or the nature of the ligand. In this paper, we studied the role of GPR17 in hemostasis, which is a fundamental defense mechanism in the event of injury. Using zebrafish as a model system, our laboratory has studied specifically thrombocytes, which play a significant role in hemostasis. The major reasons to use zebrafish as a model system are that their thrombocytes are functionally equivalent to human platelets, the adult fish are amenable to knockdown experiments, and they are readily available in the market. This study was performed by using a piggy back knockdown method where we used a chemical hybrid of control morpholino and an antisense oligonucleotide sequence leads to the degradation the mRNA for GPR17. After knockdown GPR17 in thrombocytes, the percent difference of the thrombocytes aggregation between the control and knockdown blood samples was measured by flow cytometry. We used various thrombocyte agonists to study differences in aggregation between the control and knockdown blood samples. The study showed that knockdown of GPR17 resulted in no significant differences in percent thrombocyte aggregation between control and agonist treated samples except for a slight increase in collagen-treated samples. Thus, it appears that GPR17 has no significant role in hemostasis.
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Date: December 2015
Creator: Bohassan, Maruah Hejey
Partner: UNT Libraries

Thresholds and Legacy Effects of Tropical Floodplain Fish Assemblages in Response to Flood Attributes

Description: Natural flow regimes are critical for sustaining biodiversity and river integrity. Floods and droughts form an important component of river systems and control population sizes and species diversity across space and time. Modification of flow regimes, including disruption of the timing, magnitude and duration of flooding, is a global problem, and many new impoundments are planned for large river-floodplain ecosystems in the tropics. Flow modifications may cause dramatic non-linear responses in population sizes and have lasting effects through time, but such topics are poorly investigated over multi-year scales, especially in highly diverse tropical ecosystems. Using a long-term dataset from the Upper Paraná River floodplain, Brazil, I tested for threshold and legacy effects of fish assemblages to flood attributes, such as timing, magnitude, duration, rate of change and variation. Specifically, I hypothesized that long duration, high magnitude floods would elicit threshold responses in long-distance migratory fish species and these responses result in significant legacy effects detectable over multiple years. Consistent positive threshold responses to increasing flood duration and magnitude were detected for many species and not significantly correlated with reproductive guilds. Legacy effects were prevalent (i.e. identified for more than 90% of species) and including flood attributes from previous years increased variance explained in species abundances by 15-20% compared to contemporary flood attributes alone. Contrary to my hypotheses, flood duration did not elicit strong legacy effects and species from the same reproductive guild did not have similar legacy effects models. The prevalence of legacy effects across almost all species in this diverse study system highlights the need to consider such dynamics in other systems. My results provide targets for management and conservation actions, such as environmental flow releases from upstream reservoirs. Environmental flows releases may play a significant role in sustainability of the floodplain and other tropical floodplain ecosystems affected by ...
Date: December 2015
Creator: Hoeinghaus, Ana Paula Ferrari
Partner: UNT Libraries

Dynamics of Stream Fish Metacommunities in Response to Drought and Reconnectivity

Description: This dissertation investigates the spatio-temporal dynamics of intermittent stream fish metacommunities in response drought-induced fragmentation and re-connectivity using both field and experimental approaches. A detailed field study was conducted in two streams and included pre-drought, drought, and post-drought hydrological periods. Fish assemblages and metacommunity structure responded strongly to changes in hydrological conditions with dramatic declines in species richness and abundance during prolonged drought. Return of stream flows resulted in a trend toward recovery but ultimately assemblages failed to fully recover. Differential mortality, dispersal, recruitment among species indicates species specific responses to hydrologic fragmentation, connectivity, and habitat refugia. Two manipulative experiments tested the effects of drought conditions on realistic fish assemblages. Fishes responded strongly to drought conditions in which deeper pools acted as refugia, harboring greater numbers of fish. Variability in assemblage structure and movement patterns among stream pools indicated species specific habitat preferences in response predation, resource competition, and desiccation. Connecting stream flows mediated the impacts of drought conditions and metacommunity dynamics in both experiments. Results from field and experimental studies indicate that stream fish metacommunities are influenced by changes in hydrological conditions and that the timing, duration, and magnitude of drought-induced fragmentation and reconnecting stream flows have important consequences metacommunity dynamics.
Date: August 2015
Creator: Driver, Lucas J.
Partner: UNT Libraries

Effect of Acute Alcohol Ingestion on Resistance Exercise Induced Mtorc1 Signaling in Human Muscle

Description: The purpose of this project was to further elucidate the effects post-exercise alcohol ingestion. This project had many novel aspects including using a resistance exercise (RE) only exercise design and the inclusion of women. To our knowledge, we are the first to investigate the effect of post-RE alcohol ingestion in women. In the first chapter of this project, information on the prevalence of alcohol use and the importance of skeletal muscle as a dynamic and metabolic tissue was provided. In chapter two, the effects of post-RE alcohol ingestion in men and women are detailed. The major findings of this study was that although RE elicited similar mTORC1 signaling both in men and in women, alcohol ingestion appeared to only attenuate RE-induced phosphorylation of the mTORC1 signaling pathway in men. The third chapter focused on examining the effects of post-RE alcohol ingestion on acute testosterone bioavailability. The primary findings of this study was that alcohol substantially elevated serum total and free testosterone concentrations during recovery from a bout of resistance exercise. The fourth chapter detailed factors that contribute to bone density in men. The major findings of this study was that young adult male long-distance runners who participated in resistance training at least once per week had greater bone mineral density than their non-resistance trained and non-exercise trained peers.
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Date: August 2015
Creator: Anthony A. Duplanty
Partner: UNT Libraries

Glucose Induces Sensitivity to Oxygen Deprivation and Alters Gene Expression in Caenorhabditis Elegans

Description: An organisms’ diet represents an exogenous influence that often yields colossal effects on long-term health and disease risk. The overconsumption of dietary sugars for example, has contributed to significant increases in obesity and type-2 diabetes; health issues that are costly both economically and in terms of human life. Individuals who are obese or are type-2 diabetic often have compromised oxygen delivery and an increased vulnerability to oxygen-deprivation related complications, such as ischemic strokes, peripheral arterial disease and myocardial infarction. Thus, it is of interest to identify the molecular changes glucose supplementation or hyperglycemia can induce, which ultimately compromise oxygen deprivation responses. By utilizing the Caenorhabditis elegans genetic model system, which is anoxia tolerant, I determined that a glucose-supplemented diet negatively impacts responses to anoxia and that the insulin-like signaling pathway, through fatty acid and ceramide biosynthesis and antioxidant activity, modulates anoxia survival. Additionally, a glucose-supplemented diet induces lipid accumulation. Use of RNA-sequencing analysis to compare gene expression responses in animals fed either a standard or glucose-supplemented diet revealed that glucose impacts the expression of genes involved with multiple cellular processes including lipid and carbohydrate metabolism, stress responses, cell division, and extracellular functions. Several of the genes we identified are homologous to human genes that are differentially regulated in response to metabolic diseases, suggesting that there may be conserved gene expression responses between C. elegans supplemented with glucose and a diabetic and/or obese state observed in humans. These findings support the utility of C. elegans to model specific aspects of the T2D disease process (e.g., glucose-induced sensitivity to oxygen deprivation) and identify potentially novel regulators of common complications seen in hyperglycemic and T2D patients (e.g., macrovascular complications).
Date: August 2015
Creator: Garcia, Anastacia M.
Partner: UNT Libraries