UNT Theses and Dissertations - 152 Matching Results

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Toxicity of Polychlorinated Biphenyls (Aroclor 1254) on the Earthworm Eisenia foetida

Description: Objectives were to: (1) assess toxicity of polychlorinated biphenyls on Eisenia foetida, in terms of survival (LC5O/LD5O), and suppression of coelomocytes to form secretory (SR) and erythrocyte rosettes (ER) with, and to phagocytize rabbit erythrocytes; and (2) compare results with those of Lumbricus terrestris to assess relative sensitivities to PCB. Using 5-d filter paper contact exposure protocol, LC50 and LD50 were 30.4 cg/cm2 and 4450 cg/g dry mass, respectively. Nominal PCB exposure conce… more
Date: August 1991
Creator: Sassani, Ramin
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Mutagenized HLA DNA Constructs: Tools for Validating Molecular HLA Typing Methodologies

Description: This study describes the development and validation of mutagenized cloned DNA constructs, which correspond to the polymorphic regions of the class II region of the HLA complex. The constructs were used to verify the allelic specificity of primers and probes in polymerase chain reaction (PCR)-based HLA typing assays such as Sequence Specific Primers (SSP) and Sequence Specific Oligonucleotide Probes (SSOP). The constructs consisted of the entire polymorphic region of exon 2 of class II HLA allel… more
Date: May 1999
Creator: Schulte, Kathleen Q.
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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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Pyrimidine Nucleoside Metabolism in Pseudomonads and Enteric Bacteria

Description: Metabolic differences in the strategies used for pyrimidine base and nucleoside salvage were studied in the pseudomonads and enteric bacteria. Fluoro--analogs were used to select mutant strains of E. coli, S. typhimurium, P. putida, and P. aeruginosa blocked in one or more of the uracil and uridine salvage enzymes. HPLC analysis of cell-free extracts from wild-type and mutant strains examined the effectiveness of the selections. Evidence was found for cytidine kinase in Pseudomonas and for an a… more
Date: December 1991
Creator: Scott, Allelia Worrall
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Physiological Effects of Ascaris Suum Intestinal Microflora on 5-Hydroxytryptamine Level and Binding Sites in the Intestinal Epithelial Cells

Description: Serotonin (5-hydroxytryptamine, 5-HT) has been shown to activate carbohydrate metabolism in adult female Ascaris suum. Serotonin may be either absorbed directly from the environment or synthesized de novo from the absorbed L-tryptophan in adult female A. suum. The enzymes necessary for the synthesis of 5-HT have been identified in both intestine and muscle tissues. The serotonin absorbed from the environment is obtained either from the host's gastrointestinal contents or from the 5-HT producing… more
Date: December 1991
Creator: Shahkolahi, Akbar Mohammadpour
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SFE Fractionation and RP-HPLC Characterization of Aquatic Fulvic Acid

Description: The Supercritical Fluid Extraction (SFE) technique was used to fractionate Suwannee River reference fulvic acid (FA). The fractions were characterized by gas chromatography (GC) and reversed-phase high performance liquid chromatography (RP-HPLC). A SFE fractionation method was developed using stepwise gradient of supercritical CO₂ and methanol. Three FA fractions were separated. The average mass recovery was 102% with the coefficient of variation of 2.8%. The fractionation dynamics and the diff… more
Date: May 1994
Creator: Shao, Peimin
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Use of tRNA Gene Probes to Identify Polymorphic Loci in the Bovine Genome

Description: A 30-mer oligonucleotide probe encoding the "A box" and anticodon loop regions of a human glycine tRNA gene was used to isolate a 581bp DNA fragment from a bovine genomic DNA library. Although the cross-hybridizing segment of DNA was found not to encode any tRNA gene or pseudogene, a region with homology to the "C-element" of the "BOV-tA" type Alulike artiodactyl retroposons was identified. This cross-hybridization was determined to be the result of conserved RNA polymerase III promoter element… more
Date: August 1998
Creator: Shariat, Parvaneh
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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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Site Directed Mutagenesis of β-Ketoadipate Succinyl-Coenzyme A Transferase II from Acinetobacter Calcoaceticus

Description: The role of specific amino acid residues in β-ketoadipate succinyl-coenzyme A transferase II from Acinetobacter calcoaceticus was investigated. A 1412 base pair BamiHI-EcoRI fragment carrying the catIJ genes was amplified by polymerase chain reaction and inserted into pUCl9 to generate the plasmid pCATEl9. Escherichia coli DH5α (pCATEl9) carrying only the catlJ genes expressed 3-fold higher enzyme activity than the parent strain. Two mutants were constructed by site directed mutagenesis so that… more
Date: August 1993
Creator: Sheng, Mei
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Assessing Regional Gully Erosion Risk: A Remote Sensing and Geographic Information Systems Approach

Description: Gully erosion has been established as a major source of sediment pollution in the upper Trinity River watershed in north-central Texas. This fact, along with a lack of models appropriate for a large-area gully erosion analysis established a need for a gully erosion study in the upper Trinity basin. This thesis project attempted to address this need by deriving an index indicative of gully erosion risk using remote sensing and geographic information systems (GIS) methodology. In context of previ… more
Date: August 1995
Creator: Sill, Paul E. (Paul Eric)
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Assessing Effects of an Environmental Education Field Science Program Fostering Responsibility at an Urban Middle School

Description: The study investigated the ability of an extracurricular program to influence environmental responsibility of sixth and seventh graders. The Children's Environmental Attitude and Knowledge Survey (CHEAKS) was evaluated for appropriateness in assessing the worth of this particular environmental education strategy emphasizing water quality fieldwork and technology. CHEAKS is designed with psychometric reliability and validity that may be used in comparing disparate programs. … more
Date: May 1999
Creator: Sills, Blake
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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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Cassette Systems for Creating Intergeneric Hybrid ATCases

Description: Cassette systems for creating intergeneric hybrid ATCases were constructed. An MluI restriction enzyme site was introduced at the carbamoylphosphate binding site within the pyrB genes of both Pseudomonas putida and Escherichia coli. Two hybrids, E. coli pyrB polar domain fused with P. putida pyrB equatorial domain and P. putida pyrB polar domain fused with E. coli pyrB equatorial domain, are possible. The intergeneric E. coli-P. putida hybrid pyrB gene was constructed and found to encode an a… more
Date: December 1999
Creator: Simpson, Luci N.
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Contemporary Biology Curriculum for Non-majors

Description: The proposed biology curriculum for non-majors has one main objective, namely to improve scientific literacy among college students. The National Science Education Standards defines scientific literacy as "the knowledge and understanding of scientific concepts and processes required for personal decision making, participation in civic and cultural affairs, and economic productivity". The suggested strategies to accomplish this goal are to limit the number of topics covered, introduce relevant s… more
Date: August 1998
Creator: Smallwood, Susan
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Responses of Pristina leidyi Smith 1896 (Naididae: Oligochaeta) to Cadmium, Vanadium, and Some Environmental Factors

Description: Concern over sediment toxicity has increased the need for toxicity test information with organisms that inhabit sediments. Oligochaetes are exposed to toxicants through feeding and direct body contact with aquatic sediments. Chronic testing with oligochaetes has historically focused on tubificids with test lengths of one year or more to encompass several generations. Most naidid oligochaetes have generation times of three to seven days and could provide chronic information in a matter of weeks.… more
Date: May 1990
Creator: Smith, David P. (David Paul), 1956-
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Nutrient Effects on Autofragmentation of Myriophyllum Spicatum L.

Description: A 2 x 2 factorial design investigated effects of sediment nitrogen and water potassium levels on autofragment production. Reduced nitrogen levels significantly increased autofragment production whereas potassium levels did not significantly alter production. Up to 50% of autofragment production abscised from parent plants grown under low nitrogen conditions compared to 12% or less under high nitrogen conditions.
Date: August 1998
Creator: Smith, Dian H. (Dian Helen)
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Subcellular Localization of N-acylphosphatidyl-ethanolamine Synthase in Cotyledons of Cotton Seedlings

Description: N-acylation of phosphatidylethanolamine (PE) with free fatty acids catalyzed by N-acyl phosphatidylethanolamine (NAPE) synthase was reported in cotyledons of 24-h-old cotton seedlings. Here I report subcellular localization of this enzyme. Differential centrifugation, sucrose density gradient fractionation,aqueous two-phase partitioning and electron microscopy techniques were utilized to elucidate subcellular site(s) of NAPE synthase. Marker enzymes were used to locate organelles in subcellular… more
Date: December 1995
Creator: Sriparameswaran, Anuja
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Nesting Ecology of the Dickcissel (Spiza americana) on a Tallgrass Prairie Relict in North Central Texas

Description: Eighty-three species of vascular plants were inventoried on the prairie relict during peak dickcissel nesting. Based on foliar cover and occurrence frequency, the five dominant plants were heath aster (Aster ericoides), eastern gammagrass (Tripsacum dactyloides), little bluestem (Schizachyrium scoparium), sensitive briar (Schrankia roemeriana) and meadow dropseed (Sporobolus asper). Sixty-one percent of dickcissel nests were constructed on or immediately next to three plant species: eastern gam… more
Date: May 1993
Creator: Steigman, Kenneth Lee
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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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Naloxone Potentiation of Epinephrine Induced Vasoconstriction in Canine Skeletal Muscle Arteries

Description: Naloxone (NX) potentiated epinephrine (EPI) induced submaximal vasoconstriction in canine renal and skeletal muscle arterial segments, yet had no vasoconstrictor action alone. Developed tension generated in-vitro by 4 x 1mm. O.D. rings from 1st degree branches of canine femoral arteries was expressed as % of KCI induced maximum response. NX (10^-5 M) potentiated EPI induced submaximal contractions (34.2%) significantly more than contractions induced by norepinephrine, phenylephrine, lofexidine,… more
Date: August 1992
Creator: Stoll, Scott Thomas
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The Removal of Linseed Oil Vapors by Biodegradation

Description: Linseed oil is very important in industry but its use is limited due to noxious vapors produced by oxidation on exposure to air. Since some of the products are toxic, release of linseed oil vapors to the environment is normally prohibited. In order to remove the odorous compounds, a biofilter system based on bacterial metabolism was designed and the major premises of bioremediation were studied. A total of five bacterial strains capable of using linseed oil vapors as their sources of carbon and… more
Date: August 1996
Creator: Sukplang, Patamaporn
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Regulation of an S6/H4 Kinase in Crude Lymphosarcoma P1798 Preparations

Description: Purified S6/H4 kinase (Mr 60,000) requires autophosphorylation for activation. A rabbit anti-S6/H4 kinase peptide (SVIDPVPAPVGDSHVDGAAK) antibody recognized both the S6/H4 kinase holoenzyme and catalytic domain. Immunoreactivity with p60 kinase protein, and S6/H4 kinase activity were precisely correlated in fractions obtained from ion exchange chromatography of P1798 lymphosarcoma extracts. An enzyme which catalyzed the MgATP-dependent phosphorylation and activation of S6/H4 kinase coeluted wit… more
Date: December 1998
Creator: Taylor, Allison Antoinette
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Nicotinic Acetylcholine Receptor α3 mRNA in Rat Visual System After Monocular Deprivation

Description: In situ hybridization was used to examine effects of monocular enucleation on nicotinic acetylcholine receptor subunit cc3 mRNA in the rat dLGNand visual cortex. After 28 days postoperative, there were no significant differences in α3 mRNA density between the contralateral (deprived) and ipsilateral (non-deprived) sides. The lack of obvious effects of visual deprivation on α3 mRNA density suggests that other factors, possibly intrinsic to dLGNand visual cortex, govern the postnatal expression o… more
Date: August 1997
Creator: Taylor, James H. (James Harvey), 1970-
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