UNT Theses and Dissertations - 831 Matching Results

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Site Directed Mutagenesis of Dienelactone Hydrolase

Description: The clcD gene encoding dienelactone hydrolase (DLH) is part of the clc gene cluster for the utilization of the B-ketoadipate pathway intermediate chlorocatechol. The roles that individual amino acids residues play in catalysis and binding of the enzyme were investigated. Using PCR a 1.9 kbp clcD fragment was amplified and subcloned yielding a 821 bp BamHi to ZscoRI subclone in the plasmid pUC19.
Date: August 1995
Creator: Al-Khatib, Haifa Yousef
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A Behavioral Model for Detection of Acute Stress in Bivalves

Description: A behavioral model for acute responses in bivalves, was developed using time series analysis for use in a real-time biomonitoring unit. Stressed bivalves closed their shell and waited for the stressful conditions to pass. Baseline data showed that group behavior of fifteen bivalves was periodic, however, individuals behaved independently. Group behavior did not change over a period of 20 minutes more than 30 percent, however, following toxic exposures the group behavior changed by more than 30 … more
Date: May 1998
Creator: Allen, H. Joel
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Documentation of Biodiversity Impacts (Including Cumulative Biodiversity Impacts) in Environmental Impact Statements

Description: In the United States, biodiversity impact assessment has historically received little attention. Responding in 1993, the Council on Environmental Quality (CEQ) released guidelines on incorporating biodiversity into environmental impact assessment under the National Environmental Policy Act of 1969. The objectives of the study here were to identify the level of documentation of biodiversity impact assessment in sample Environmental Impact Statements (EISs); identify whether in the years followin… more
Date: August 1998
Creator: Bhatia, Sarika
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Cardiorespiratory Responses to Graded Levels of Lower-body Positive Pressure During Dynamic Exercise in Man

Description: Cardiorespiratory responses to incremental dynamic exercise were assessed across four different levels of lower-body positive pressure (LBPP) and, as a separate study, during constant load (i.e constant work rate) exercise below and above each subject's ventilatory threshold (VT), both with and without 45 torr of LBPP.
Date: December 1992
Creator: Williamson, Jon W. (Jon Whitney)
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Regulation of Escherichia coli pyrBI Gene Expression in Pseudomonas fluorescens

Description: Pseudomonas fluorescens does not appear to regulate the enzymes of de novo pyrimidine biosynthesis at the level of gene expression. Little or no apparent repression of pyr gene expression is observed upon addition of exogenous pyrimidines to the growth medium. The Escherichia coli pyrBI genes for aspartate transcarbamoylase (ATCase) were sized down and cloned into the broad host range plasmid, pKT230. Upon introduction into a P.fluorescenspyrB mutant strain, ATCase showed repression in response… more
Date: May 1995
Creator: Shen, Weiping
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Construction of a Cloning Vector Based upon a Rhizobium Plasmid Origin of Replication and its Application to Genetic Engineering of Rhizobium Strains

Description: Rhizobia are Gram-negative, rod-shaped, soil bacteria with the ability to fix atmospheric nitrogen into ammonia as symbiont bacteroids within nodules of leguminous plant roots. Here, resident Rhizobium plasmids were studied as possible sources of components for the construction of a cloning vector for Rhizobium species.
Date: May 1992
Creator: Jeong, Pyengsoo
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Functional Properties and Organization of Primary Somatosensory Cortex

Description: The physiological characteristics and organization of cat primary somatosensory cortex (SI) were studied in electrophysiological and anatomical experiments. In single cell recording experiments, quantitatively controlled mechanical stimuli were used to examine the responses of SI cortical neurons to the velocity component of skin or hair displacement. The firing frequency of most rapidly adapting neurons increased as stimulus velocity was increased. Rapidly adapting neurons were classified base… more
Date: December 1993
Creator: Esteky, Hossein
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Pyrimidine Salvage Enzymes in Microorganisms: Labyrinths of Enzymatic Diversity

Description: Pyrimidine salvage pathways are essential to all cells. They provide a balance of RNA synthesis with the biosynthetic pathway in pyrimidine prototrophs and supply all the pyrimidine requirements in auxotrophs. While the pyrimidine biosynthetic pathway is found in almost all organisms and is nearly identical throughout nature, the salvage pathway often differs from species to species, with aspects of salvage seen in every organism. Thus significant taxonomic value may be ascribed to the salvage … more
Date: December 1995
Creator: Beck, Debrah A. (Debrah Ann)
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Effects of a Methylcholanthrene-Induced Lymphosarcoma on Various Tissues of DBA/1J and Swiss White Mice

Description: This investigation was concerned with characterizing effects of this tumor line on lipid metabolism in DBA/lJ mice and serum protein levels and cellular changes in DBA/lJ and Swiss white mice. Total lipids, lipid phosphorus, neutral lipids, and changes in fatty acids were determined in liver, spleen, skin, and tumor of DBA/lJ mice bearing the lymphosarcoma at various days after injection of tumor cells.
Date: May 1973
Creator: Lindsey, Terri Jay
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Characterization of a Human 28S Ribosomal RNA Retropseudogene and Other Repetitive DNA Sequence Elements Isolated from a Human X Chromosome-Specific Library

Description: Three genomic clones encompassing human DNA segments (designated LhX-3, LhX-4, and LhX5) were isolated from an X chromosome-specific library and subjected to analysis by physical mapping and DNA sequencing. It was found that these three clones are very rich in repetitive DNA sequence elements and retropseudogenes.
Date: May 1994
Creator: Wang, Suyue
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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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Evaluating Fish Impingement and Entrainment at the Comanche Peak Steam Electric Station

Description: This study was designed to determine if impingement and entrainment by cooling water intake at the Comanche Peak Steam Electric Station have an adverse impact upon the Squaw Creek Reservoir fish population. The yearly impingement of fish was estimated to be 262,994 of 14 species. The threadfin shad (Dorosoma petenense) accounted for 96% of this total. Entrainment of eggs and larvae for a five month period was estimated to be 15,989,987 and 42,448,794 respectively. Two fish population studies we… more
Date: May 1996
Creator: Bauml, George A. (George Arthur)
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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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Subcloning and Nucleotide Sequence of Two Positive Acting Regulatory Genes, xy1R and xy1S, from the Pseudomonas putida HS1 TOL Plasmid PDK1

Description: TOL plasmids of Pseudomonas putida encode enzymes for the degradation of toluene and related aromatics. These genes are organized into two operons regulated by the Xy1R and Xy1S transcriptional activators. Previous analysis of the TOL pDK1 catechol-2,3-dioxygenase gene (xy1E) and a comparison of this gene to xy1E from the related TOL plasmid pWW0, revealed the existance of a substantial level of sequence homology (82%).
Date: May 1992
Creator: Chang, Teh-Tsai
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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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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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Conception and Design of Constructed Wetland Systems to Treat Wastewater at the Biosphere 2 Center with Use of Reaction Rate Models and the Habitat Evaluation Procedure to Determine the Effects of Designing for Wildlife Habitat on Treatment Efficiency

Description: A study was undertaken to explore relationships between wetland characteristics which make them efficient water purifiers versus their ability to serve as wildlife habitat. The effects of designing constructed wetlands for improved habitat on water treatment efficiencies were quantified. Results indicate that some sacrifice in treatment efficiency is required and that the degree of efficiency reduction is dependant upon pollutant loading rates. However, sacrifice in efficiency is much smaller t… more
Date: May 1998
Creator: Clingenpeel, Glenn C. (Glenn Christopher)
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Nucleotide Sequence Determination, Subcloning, Expression and Characterization of the xy1LT Region of the Pseudomonas putida TOL Plasmid pDK1

Description: The complete nucleotide sequence of the region encoding the DHCDH function of the pDK1 lower operon was determined. DNA analysis has shown the presence of two open reading frames, one gene consisting of 777 nucleotides encoding a polypeptide of 27.85 kDa and another gene of 303 nucleotides encoding a polypeptide of 11.13 kDa. The results of enzymatic expression studies suggest that DHCDH activity is associated only with xy1L. However although the addition of xy1T cell-free extracts to xy1L cell… more
Date: December 1992
Creator: Baker, Ronald F. (Ronald Fredrick)
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Phagocytosis by Earthworm Coelomocytes : A Biomarker for Immunotoxicity of Hazardous Waste Site Soils

Description: Several biomarkers (cell viability and phagocytosis) based on earthworm (Lumbricus terrestris) immune cells (coelomocytes), together with whole-worm mortality (LC/LD50's), were used to assess a bioremediation attempt to reduce pentachlorophenol (PCP) toxicity in a former wood processing hazardous waste site (HWS).
Date: December 1997
Creator: Giggleman, Marina A.
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Cell-Free Recovery and Isotopic Identification of Cyanide Degrading Enzymes from Pseudomonas Fluorescens

Description: Cell-free extracts from Pseudomonas fluorescens NCIMB 11764 catalyzed the degradation of cyanide into products that included C02, formic acid, formamide and ammonia. Cyanide-degrading activity was localized to cytosolic cell fractions and was observed at substrate concentrations as high as 100 mM. Two cyanide degrading activities were identified by: (i) the determination of reaction products stoichiometries, (ii) requirements for NADH and oxygen, and (iii) kinetic analysis. The first activity p… more
Date: December 1995
Creator: Wang, Chien-Sao
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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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Hooking Mortality of Largemouth Bass Caught on Controversial Artificial Lures and Live Bait : Lake Ray Roberts, Texas

Description: A total of 192 largemouth bass were caught at Lake Ray Roberts, Texas (1995) to investigate five controversial bass angling techniques relative to hooking mortality. The bait types were Texas-rigged scented and non-scented plastic worms, Carolina-rigged scented and non-scented plastic worms, and live golden shiners. Overall hooking mortality was 21.87% and mortality was dependent upon bait type. Highest mortality resulted from the Texas-rigged scented lures, while the lowest mortality was gener… more
Date: May 1996
Creator: Alumbaugh, Andrew E. (Andrew Edward)
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Medial Medulla Networks in Culture: a Multichannel Electrophysiologic and Pharmacological Study

Description: Spontaneously active primary cultures obtained from dissociated embryonic medial medulla tissue were grown on microelectrode arrays for investigating burst patterns and pharmacological responses of respiratory-related neurons. Multichannel burst rates and spike production were used as primary variables for analysis. Pacemaker-like neurons were identified by continued spiking under low Ca++/high Mg++conditions. The number of pacemakers increased with time under synaptic blocking medium. Sensitiv… more
Date: August 1998
Creator: Keefer, Edward W. (Edward Wesley)
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