UNT Theses and Dissertations - 36 Matching Results

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Analysis of the Trypanosoma brucei Genome and Identification and Characterization of a Gene Family Encoding Putative EF-Hand Calcium-Binding Proteins

Description: The flagellum of Trypanosoma brucei contains a family of antigenically related EF-hand calcium-binding proteins which are called the calflagins. Genomic Southern blots indicated that multiple copies of calflagin genes occur in T brucei. All of the copies were contained in a single 23 kb Xhol-Xhol fragment. Genomic fragments of 2.5 and 1.7 kb were cloned that encoded calflagin sequences. Two new members of the calflagin family were found from genomic clone sequences. The deduced amino acid seque… more
Date: May 1998
Creator: DeFord, James H. (James Henry), 1956-
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Assembly of Pseudomonas putida Aspartate Transcarbamoylase and Possible Roles of the PyrC' Polypeptide in the Folding of the Dodecameric Enzyme

Description: Aspartate transcarbamoylase (ATCase) of Pseudomonas putida consists of two different polypeptides, PyrB and PyrC' (Schurr et al, 1995). The role of the PyrC' and the assembly of PyrB and PyrC' have been studied. The ATCase made in vitro of P.putida PyrB with P.putida PyrC', and of E.coli PyrB with P.putida PyrC ' were generated under two different conditions, denaturation and renaturation, and untreated. It was found that PyrC' plays a role in the enzymatic regulation by ATP, CTP and UTP. In … more
Date: May 1999
Creator: Hongsthong, Apiradee, 1970-
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Biochemical Identification of Molecular Components Required for Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764

Description: Utilization of cyanide as a nutritional nitrogen source in P. fluorescens NCIMB 11764 was shown to involve a novel metabolic mechanism involving nonenzymatic neutralization outside of cells prior to further enzymatic oxidation within. Several cyanide degrading enzymes were produced by NCIMB 11764 in response to growth or exposure to cyanide, but only one of these cyanide, oxygenase (CNO), was shown to be physiologically required for assimilation of cyanide as a growth substrate.
Date: May 1998
Creator: Chen, Jui-Lin
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Biodiversity of Caddisflies (Trichoptera) of the Interior Highlands of North America

Description: Caddisflies (Trichoptera) were collected from over 500 different locations throughout the Interior Highlands (Ozark, Ouachita, Arbuckle, and Wichita Mountains) between March 1990 and March 1994. I systematically sampled representative lotic and lentic habitats in 131 natural watersheds that comprise the 17 different physiographic subregions of this area. From my examination of approximately 60,000 specimens, surveys of regional museum collections, and review of literature records, I document 22… more
Date: August 1994
Creator: Moulton, Stephen R. (Stephen Richard)
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Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces

Description: The south-central United States serves as an important biogeographical link and dispersal corridor between Nearctic and Neotropical elements of western hemisphere odonate faunas. Its species are reasonably well known because of substantial collections, but there has been no concerted effort to document the extent of biodiversity and possible geographic affinities of dragonflies and damselflies of this region. The recent discoveries of Argia leonorae Garrison, Gomphus gonzalezi Dunkle and Erpeto… more
Date: May 1999
Creator: Abbott, John C.
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Biogeographic Relationships of Pocket Gophers (Geomys breviceps and Geomys bursarius) in the Southeastern Portion of Their Ranges

Description: This research utilized population genetic analyses (protein starch-gel electrophoresis and DNA sequencing of the cytochrome b mtDNA gene), host-parasite specificity (lice coevolution), remote sensing of satellite data, and geographic information systems (GIS) to characterize newly discovered populations of pocket gophers (genus: Geomys) in Arkansas. These populations are isolated and occur in seemingly unsuitable habitat in the Ozark Mountains of Arkansas. Analyses of electrophoretic and ectopa… more
Date: August 1998
Creator: Elrod, Douglas Allen
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Blood Pressure Regulation During Simulated Orthostatism Prior to and Following Endurance Exercise Training

Description: Cardiovascular responses and tolerance to an orthostatic stress were examined in eight men before and after eight months of endurance exercise training. Following training, maximal oxygen consumption and blood volume were increased, and resting heart rate reduced. Orthostatic tolerance was reduced following training in all eight subjects. It was concluded that prolonged endurance training decreased orthostatic tolerance and this decrease in tolerance appeared associated with attenuated barorefl… more
Date: May 1992
Creator: Stevens, Glen Harold John
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Characterization of Aspartate Transcarbamoylase in the Archaebacterium Methanococcus Jannaschii

Description: Asparate transcarbamoylase catalyzes the first committed step in the de novo synthesis of pyrmidine nucleotides UMP, UDP, UTP, and CTP. The archetype enzyme found in Escherichia coli (310 kDa) exhibits sigmodial substrate binding kinetics with positive control by ATP and negative control with CTP and UTP. The ATCase characterized in this study is from the extreme thermophilic Archaebacterium, Methanococcus jannaschii. The enzyme was very stable at elevated temperatures and possessed activity fr… more
Date: December 1996
Creator: Stewart, John E. B. (John Edward Bakos)
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Dalbergia and Albizia: Plantlet Production via Tissue Culture, Karyological Evaluation, and Seed Anatomy with Scanning Electron Microscopy

Description: A publication by the National Academy of Sciences, USA (1979) outlined some of the research need for a great variety of economically important woody species whose remaining genetic resources need urgently to be collected and conserved. A viable regeneration system was established via tissue and cell suspension culture for Albizia falcataria and A. lebbeck, two important wood yielding leguminous tree species. The culture medium was standardized after several trials to obtain callus from the leaf… more
Date: December 1998
Creator: Ghosh, Nabarun
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Development of Cardiovascular Regulation in Embryos of the Domestic Fowl (Gallus Gallus), with a Partial Comparison to Embryos of the Desert Tortoise (Gopherus Agassizii)

Description: In adult vertebrates, cardiovascular regulation is accomplished by numerous systems with neural, hormonal and local components responsible for the majority of regulation. These regulatory components work in concert to maintain the essential function of blood perfusion to adult tissues. Given the essential nature of this function it is therefore surprising that the development of cardiovascular regulation during gestation is poorly understood. The majority of what is known is based on a single v… more
Date: August 1999
Creator: Crossley, Dane Alan
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Discovery and Characterization of Two Tn5 Generated pyrA Mutants in Pseudomonas putida and the Generation of Hfr Strains

Description: A pyrA mutation in Pseudomonas putida was isolated using transposon mutagenesis for the first time. Transposon Tn5 was used to inactivate the pyrA gene for carbamoylphosphate synthetase in these mutants. Accordingly, these mutants were defective in pyrimidine and arginine biosynthesis. The suicide vector, pM075, from Pseudomonas aeruginosa, was used to introduce the transposon into the cells. Tn5 was subsequently used to supply homology so that the plasmid pM075 could be introduced in its entir… more
Date: August 1994
Creator: Liljestrand, Laura Gail
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Effects of Trichinella Soluble Antigens on Macrophage Subpopulations

Description: The immunomodulatory effects of Trichinella spiralis or Trichinella pseudospiralis soluble antigen extracts were examined in an effort to characterize the differences in immune responses seen during these Trichinella infections. The newborn larvae extracts of either parasite exhibited similar potency for stimulating macrophage PGE production; however, the muscle larvae extracts of T. pseudospiralis stimulated greater levels of PGE than did the muscle larvae extracts of T. spiralis. These data c… more
Date: August 1992
Creator: Dixon, Guy Cameron, 1960-
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Enzyme Assays Using Earthworms for Assessing Innate and Nonspecific Immunotoxicity of Xenobiotics

Description: Principal objectives of my research were to: (1) report for the first time that coelomocytes are able to reduce NBT dye and confirm the presence of lysozyme-like activity in earthworm; (2) develop a standard methodology for determination of NBT reduction and lysozyme-like activity in earthworms; (3) compare NBT reduction and lysozyme-like activity in earthworms with those of murine and human cells and fluids; and (4) demonstrate the sensitivity of earthworm NBT reduction and lysozyme-like activ… more
Date: May 1992
Creator: Chen, Shing-Chong
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The Eosinophil Response in Mice Infected with Trichinella spiralis or Trichinella pseudospiralis as Indicated by Phospholipase B Activity

Description: The host eosinophil response was compared in mice infected with either T. spiralis or T. pseudospiralis by determination of levels of splenic and intestinal phospholipase B, a marker enzyme for eosinophils. Primary infection of naive mice and challenge infection of homologously sensitized mice with T. pseudospiralis resulted in significantly lower tissue phospholipase B activities than infection with T. spiralis. Mice homologously challenged with T. pseudospiralis did exhibit an anamnestic eosi… more
Date: December 1992
Creator: Hsu, Shing-Chien
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Eutrophication Monitoring and Prediction

Description: Changes in trophic status are often related to increases or decreases in the allocthonous inputs of nutrients from changes in land use and management practices. Lake and reservoir managers are continually faced with the questions of what to monitor, how to monitor it, and how much change is necessary to be considered significant. This study is a compilation of four manuscripts, addressing one of these questions, using data from six reservoirs in Texas.
Date: December 1993
Creator: Cairns, Stefan H., 1949-
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Interactions between Carotid and Cardiopulmonary Baroreceptor Populations during Dynamic Exercise in Man

Description: During dynamic exercise the arterial baroreflexes have been thought to reset to the prevailing level of systemic pressure in order to modulate transient changes in blood pressure with the same sensitivity (gain) as at rest. To test this hypothesis, cardiovascular responses to dynamic exercise and carotid baroreflex responses to graded neck suction and neck pressure (NS/NP) were examined in seven men of moderate fitness (V02 = 41.4±3.6 ml O2*kg^-1*min^-1) during two levels (20% and 40% of peak o… more
Date: May 1993
Creator: Potts, Jeffrey Thomas
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Isolation and Characterization of a New Capsule-Forming Bacterium

Description: A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the op… more
Date: May 1999
Creator: Thongmee, Acharawan
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Isolation, Characterization and Physiological Studies of Cyanide-Utilizing Bacteria

Description: Ten bacteria capable of growth on the metal-cyano complex, tetracyanonickelate (II) {K2 [Ni(CN)J } (TCN), supplied as the sole nitrogen source, were isolated. Seven isolates were identified as pseudomonads while the remaining three were classified as Klebsiella species. In addition to TCN, all isolates were able to utilize KCN although it was significantly more toxic. The degradation of TCN was most complete when supplied at growth-limiting concentrations, did not occur when ammonia was present… more
Date: December 1991
Creator: Silva Avalos, Juan G. (Juan Guillermo)
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Mechanisms of Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764

Description: Pseudomonas fluorescens NCIMB 11764 was capable of utilizing cyanide as a sole nitrogen source for growth. Cyanate (OCN") and S-cyanoalanine could also serve as nitrogenous substrates, but do not appear to play a role as intermediates in cyanide metabolism. Growth of this strain on cyanate as the sole nitrogen source led to the induction of an enzyme characterized as a cyanase (EC 3.5.5.3) based on its stoichiometric conversion of cyanate to ammonia, and dependence on bicarbonate for maximal ac… more
Date: August 1992
Creator: Nagappan, Olagappan
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Modifications in Cellular Responses of Mononuclear Cells Exposed to Mycobacterium Avium Serovar-specific Glycopeptidolipid and Its Lipopeptide Fragment

Description: Immunological and ultrastructural changes in mononuclear cells exposed to Mycobacterium avium serovar-specific glycopeptidolipid (GPL) and the chemically derived R-lipid (lipopeptide fragment) were examined.
Date: December 1992
Creator: Pourshafie, Mohammed R.
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Molecular and Kinetic Characterization of the Aspartate Transcarbamoylase Dihydroorotase Complex in Pseudomonas putida

Description: Aerobic Gram negative bacteria such as Pseudomonas putida were reported to possess class A ATCases and to have a M.W. of 360 kD. The nucleotide sequence of the P. putida pyrBC was determined to answer this question once and for all. The expected regulatory gene was not found. It is shown that the P. putida pyrB gene is overlapped by pyrC by 4 bp. The P.putida pyrB is 1005 bp (335 aa) in length and the pyrC is 1275 bp (425 aa) long. Both of these genes complement E. coli mutants with their respe… more
Date: May 1992
Creator: Schurr, Michael J. (Michael John)
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Molecular Phylogeny and Evolution of the American Woodrats, Genus Neotoma (Muridae)

Description: The evolutionary relationships of woodrats (Neotoma) were elulcidated through phylogenetic analyses of mitochondrial DNA restriction site and allozyme data. DNA samples from eleven nominal species from the genus Neotoma and two outgroup taxa, Ototylomys phyttotis and Xenomys nelsoni, were cleaved using a suite of 17 Type II restriction endonucleases. Mitochondrial DNA restriction profiles were visualized following electrophoresis of restriction digests via methods of Southern transfer and hybri… more
Date: August 1992
Creator: Planz, John Valentine
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Morphological and Immunological Characterization of Earthworm Lumbricus terrestris Coelomocytes

Description: This research defines the morphological characteristics of the immune cells, coelomocytes, of the earthworm, Lumbricus terrestris. Such a definition of coelomocyte morphology can be correlated with immune function which will be of value in the development of a nonmammalian surrogate system to assess the immunotoxic potential of a terrestrial xenobiotics. Earthworms exposed to artificial soil dilutions of two complex xenobiotic mixtures, refuse derived fuel fly ash and a Superfund sire soil demo… more
Date: August 1992
Creator: Hariri, Maryam Feili
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