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UNT Theses and Dissertations
Molecular systematics of Baird's pocket gopher (Geomys breviceps)
Date: August 2010
Creator: Bodine, Deanna Martinez
Description: 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.
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Thermal Stress During Pre-Incubation Induces Subsequent Developmental Plasticity in Northern Bobwhites
Date: August 2010
Creator: Reyna, Kelly Shane
Description: 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 ≤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 ...
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Comparison of Heteranthera Dubia (Jacq.) MacM.-associated Macroinvertebrates Between Georgraphical Regions in the United States
Date: May 2010
Creator: Harms, Nathan Earl
Description: Macroinvertebrates associated with the aquatic plant, water stargrass (Heteranthera dubia), were sampled from 12 waterbodies in four regions of the United States from June to August 2005. Taxa richness, evenness, and diversity were lowest in the Lower Midwest (LMW) region, and higher in Northern sites, especially the Upper Midwest (UMW), and Northeast (NE). While relative abundance varied from site to site and region to region, utilization of the plant by functional groups remained fairly constant. Collector-gatherers consistently comprised the largest portion of invertebrates sampled. The shredder/ herbivore functional group comprised an average of 17 % of total groups. Through an exhaustive literature review, it was found that shredder/ herbivores of water stargrass have not been reported in the literature. Because of this, the herbivore group was analyzed separately and consisted of 2,383 specimens representing 23 species. The most common groups were Rhopalosiphum sp., Nectopsyche spp. and chironomids. No differences were found in herbivore diversity or evenness between sampling regions, but species richness was significantly different.
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Permallink:digital.library.unt.edu/ark:/67531/metadc28427/
Modulation of the Coelomic Fluid Protein Profile in the Earthworm, Lumbricus Terrestris, After Exposure to Copper as Copper Sulfate
Date: May 2010
Creator: Herring, Reese
Description: Proteomic techniques were used to analyze the protein profile of earthworm, Lumbricus terrestris, coelomic fluid collected by either whole body dissection method or the coelomic cavity puncture method. Data demonstrated that collection of coelomic fluid using the coelomic cavity puncture method protocol resulted in a 32% reduction, 377 +/- 4.5 vs 253+/- 19.9 (p=0.0007), in the number of individual proteins. It was determined that the coelomic cavity puncture method yielded a "cleaner" preparation, one less contaminated with extraneous proteins from intestinal tissue, gut contents, and body wall materials. This protocol was used in all later studies. The same proteomic techniques were used to evaluate the effects that exposure to Cu (1.0 μg/cm2) as CuSO4 had on the earthworm coelomic fluid profile. Comparison of protein profile from exposed earthworms demonstrated a significant reduction in the number of proteins expressed (184 ± 2.64 vs 253 ±19.9 p=0.0192) when compared to control organisms. Cu exposure also resulted in a modulation of the protein profile with treated earthworms expressing 47 new proteins that were not identified in unexposed worm coelomic fluid. Additionally, 116 proteins found in coelomic fluid collected from normal worms were absent in Cu exposed organisms. Finally, 137 proteins were conserved or ...
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Hypoxic and hyperoxic incubation affects the ductus arteriosus in the developing chicken embryo (Gallus gallus).
Date: December 2009
Creator: Copeland, Jennifer
Description: Developing chicken embryos have two ductus arteriosus (DA) that shunt blood away from the lungs and to the chorioallantoic membrane, the embryonic gas exchanger. In mammals, DA closure is stimulated by an increase in blood gas O2 that occurs as the animal begins to breathe with its lungs. The goal of this study was to determine the influence of O2 levels during incubation on the vascular reactivity and morphology of the O2-sensitive DA and to examine the effects of changing O2 levels during late incubation on the morphology of the DA from chicken embryos. In comparison to normoxia, hypoxia (15%) reduced venous O2 levels in day 16 and day 18 embryos and reduced aircell O2 values in day 16, day 18, and internally pipped (IP) embryos, whereas hyperoxia (30%) increased venous O2 levels and aircell O2 level in day 16, day 18, and IP embryos. In comparison to normoxia, hypoxia delayed closure of the DA, whereas hyperoxia accelerated DA closure. In comparison to the left DA from externally pipped (EP) normoxic embryos, the left DA from EP hypoxic embryos exhibited a significantly weaker contractile response to O2. The DA from day 18 hypoxic embryos exhibited a significantly weaker contractile response ...
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In vitro Cultures of Morus alba for Enhancing Production of Phytoestrogens
Date: December 2009
Creator: Bakshi, Vibhu
Description: Plant estrogens have long been associated with health benefits. The potential of tissue culture techniques for the production of several secondary metabolites has been known for many years. Tissue cultures stimulate the production or induce the biosynthesis of novel compounds not found in the mature plant. Tissue culture of Morus alba, family Moraceae, is known to contain phytoestrogens, was established on plant-hormone supplemented Murashige and Skoog (MS) medium. Petiole and the stem tissue from mature trees were the best explants for initiation and proliferation of calli. The best callus proliferation was obtained on MS medium containing 1-napthalene acetic acid (1mg/ml) and benzylaminopurine (0.5mg/ml) for M. alba. Comparison of phytoestrogens of Moraceae species from in vivo and in vitro tissue isolation were carried out. The estrogenic activities of callus extracts were assayed in an estrogen-responsive yeast system expressing the human estrogen receptor alpha. Male callus extracts had higher estrogenic activity than male and female extracts from in vivo and in vitro tissues. Isolation and characterization of phytoestrogens from above tissues were carried out using solid phase extraction, high perfomance liquid chromatography and mass spectrometry techniques. Biochanin A, an isoflavonoid, was isolated as one of the compounds in male callus extracts. Biochanin ...
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Investigation of cryopreservation methods for adherent nerve cell networks in vitro.
Date: December 2009
Creator: Webb, Veronica Fine
Description: Cryopreservation in suspension is commonplace for a variety of cell types. However, cryopreservation of adherent cells has achieved limited success. This research aimed to cryopreserve adherent nerve cell networks in vitro in a manner that preserved network morphology and physiology. Successful implementation would enable long term storage of adherent neuronal networks on microelectrode arrays and on-demand access for use in pharmacological and toxicological testing. Based upon morphological assessments, excellent post-thaw preservation was obtained and post-thaw cultures survived in a transitional medium for up to 3.5 hours. However, transitions to native culture medium post-thaw presented difficulties, ultimately resulting in necrosis. A discussion of methods to supplement the current research and increase post-thaw viability is included in the thesis.
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Permallink:digital.library.unt.edu/ark:/67531/metadc12213/
Metabolic, cardiac and ventilatory regulation in early larvae of the South African clawed frog, Xenopus laevis.
Date: December 2009
Creator: Pan, Tien-Chien
Description: Early development of O2 chemoreception and hypoxic responses under normoxic (150 mmHg) and chronically hypoxic (110 mmHg) conditions were investigated in Xenopus laevis from hatching to 3 weeks post fertilization. Development, growth, O2 consumption, ventilatory and cardiac performance, and branchial neuroepithelial cells (NEC) density and size were determined. At 3 days post fertilization (dpf), larvae started gill ventilation at a rate of 28 ± 4 beats/min and showed increased frequency to 60 ± 2 beats/min at a PO2 of 30 mmHg. Also at 3 dpf, NECs were identified in the gill filament buds using immunohistochemical methods. Lung ventilation began at 5 dpf and exhibited a 3-fold increase in frequency from normoxia to a PO2 of 30 mmHg. Hypoxic tachycardia developed at 5 dpf, causing an increase of 20 beats/min in heart rate, which led to a 2-fold increase in mass-specific cardiac output at a PO2 of 70 mmHg. At 10 dpf, gill ventilatory sensitivity to hypoxia increased, which was associated with the increase in NEC density, from 15 ± 1 to 29 ± 2 cells/mm of filament at 5 and 10 dpf, respectively. Unlike the elevated rate, cardiac and ventilatory volumes were independent of acute hypoxia. Despite increased cardioventilatory frequency, ...
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Cardio-respiratory ontogeny and the transition to bimodal respiration in an air breathing fish, the blue gourami (Trichogaster trichopterus): Morphological and physiological development in normoxia and hypoxia.
Date: August 2009
Creator: Blank, Tara M.
Description: As selection pressures exist for not only adults, but for every life history stage, it is important to understand how environmental factors shape developing animals. Despite the significance placed on aquatic hypoxia as a driving force in the evolution of air breathing, this is the first known study to examine the effects of hypoxia on cardio-respiratory ontogeny of an air breathing fish. Blue gouramis are obligatory air breathing fish that possess a labyrinth-like structure that serves as the air breathing organ. Gouramis were reared for up to 90 d in normoxia or hypoxia, and morphological and physiological development was observed. Hypoxic larvae had increased lamellar and labyrinth organ surface areas. Bradycardia and increased gill ventilation rates were observed when larvae from either rearing group were briefly exposed to hypoxia. Hypoxic larvae also showed a reduced heart rate and gill ventilation rate in the absence of a hypoxic stimulus, possibly indicative of a more comprehensive, long-term respiratory plasticity. The similarity of routine oxygen consumption between rearing groups suggests that metabolic demand did not change for hypoxic larvae, but that they were more efficient at oxygen acquisition. This is further supported by increased resistance time of hypoxic gouramis to extreme hypoxia. The ...
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Permallink:digital.library.unt.edu/ark:/67531/metadc11056/
Effects of triclosan, triclocarban, and caffeine exposure on the development of amphibian larvae.
Date: August 2009
Creator: Palenske, Nicole Marie
Description: Triclosan and triclocarban are antimicrobials found in numerous consumer products, while caffeine is the most commonly consumed stimulant by humans. This study was undertaken to determine the effects of triclosan, triclocarban, and caffeine on the development and physiology of amphibian larvae. LC50 values of triclosan and triclocarban were determined after 96 hours for three North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a common amphibian developmental model: Xenopus laevis. Amphibian larvae were most sensitive to triclosan and triclocarban exposure during early development based upon 96-hour LC50 values. Heart rates for X. laevis and North American larvae exposed to triclosan were variable throughout development. However, significantly lower heart rates were observed in all larvae exposed to triclocarban. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to triclosan were significantly affected in larvae exposed to ½ LC50 and the LC50 concentration. Metabolic rates of X. laevis larvae exposed to triclocarban were significantly affected by exposure to ½ LC50 concentrations in three of four stages investigated. No significant differences were observed in North American larvae exposed to triclocarban. Tissue uptake, lipid uptake, tissue bioconcentration factor (BCF) and lipid BCF of triclosan and triclocarban were investigated ...
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