161 Matching Results

Search Results

Structural Analysis of the TOL pDK1 xylGFJQK Region and Partial Characterization of the xylF and xylG Gene Products

TOL plasmids encode enzymes responsible for utilization of toluene and related aromatic compounds by Pseudomonas putida, ultimately converting them to central metabolic intermediates. The nucleotide sequence for the 5.6 kb xylGFJQK region of the pDK1 TOL meta operon was determined. DNA sequence analysis revealed the presence of five open reading frames corresponding to xylG (1458 bp), xylF (846 bp), xylJ (783 bp), xylQ (936 bp) and xylK (1047 bp), encoding predicted protein products of 51.6, 3… more

Access: Restricted to UNT Community Members. Login required if off-campus.

Date: December 1999

Creator: Poulter, Melinda D.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Investigation of Pyrimidine Salvage Pathways to Categorize Indigenous Soil Bacteria of Agricultural and Medical Importance and Analysis of the Pyrimidine Biosynthetic Pathway's Enzyme Properties for Correlating Cell Morphology to Function in All Phases of Growth

This dissertation comprises three parts and is presented in two chapters. Chapter 1 concerns Arthrobacter, a bacterium with an intriguing growth cycle. Whereas most bacteria exist as either a rod or coccus, this bacterium shares the rod/coccus lifestyle. It therefore seemed important to examine the growth regulatory pathways from the rod and coccus. The committed step, that catalyzed by aspartate transcarbamoylase (ATCase), in the pyrimidine biosynthetic pathway was chosen. The ATCase in Arthr… more

Date: May 2003

Creator: Meixner, Jeffery Andrew

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Cottonseed Microsomal N-Acylphosphatidylethanolamine Synthase: Identification, Purification and Biochemical Characterization of a Unique Acyltransferase

N-Acylphosphatidylethanoiamine (NAPE) is synthesized in the microsomes of cotton seedlings by a mechanism that is possibly unique to plants, the ATP-, Ca2+-, and CoA-independent acylation ofphosphatidylethanolamine (PE) with unesterified free fatty acids (FFAs), catalyzed by NAPE synthase. A photoreactive free fatty acid analogue, 12-[(4- azidosalicyl)amino]dodecanoic acid (ASD), and its 125I-labeled derivative acted as substrates for the NAPE synthase enzyme.

Date: December 1998

Creator: McAndrew, Rosemary S. (Rosemary Smith)

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Molecular and Kinetic Characterization of the Aspartate Transcarbamoylase Dihydroorotase Complex in Pseudomonas putida

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)

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Characterization of cDNA and Genomic Clones for a Palmitoyl-acyl Carrier Protein Thioesterase and an Osmotin-Like PR5 Protein in Gossypium Hirsutum.

Putative cotton cDNA clones and cognate genomic clones for a palmitoyl-acyl carrier protein (ACP) thioesterase (PATE) and an osmotin-like pathogenesis-related 5 (PR5) protein have been isolated and characterized. PATE is a class B fatty acid thioesterase with specificity for saturated long-chain fatty acids such as palmitate, and is implicated as a key enzyme to be targeted for regulation of fatty acid synthesis in order to alter cotton seed oil profiles. A nearly full-length 1.7-kb cDNA clon… more

Access: Restricted to UNT Community Members. Login required if off-campus.

Date: May 2002

Creator: Yoder, David W.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Callus Development and Organogenesis in Cultured Explants of Cowpea (Vigna unguiculata (L.) Walp

Cowpea, Vigna unguiculata (L.) Walp is an excellent source of protein, vitamins and minerals and a major food crop many parts of Africa. Optimal production levels are hampered by insect pests and diseases. Biotechnological techniques such as tissue culture and genetic engineering can aid in the development of varieties with resistance to insect pests and diseases. The objective of this study was to investigate conditions necessary for the development of a reproducible tissue culture system tha… more

Access: Restricted to UNT Community Members. Login required if off-campus.

Date: December 2004

Creator: Omwenga, George Isanda

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Purification and Characterization of Proteolytic Aspartate Transcarbamoylase (ATCase) from Burkholderia cepacia 25416 and Construction of a pyrB1 Knock-out Mutant

Burkholderia cepacia is a common soil bacterium of significance in agriculture and bioremediation. B. cepacia is also an opportunistic pathogen of humans causing highly communicable pulmonary infections in cystic fibrosis and immunocompromized patients. The pyrB gene encoding ATCase was cloned and ATCase was purified by the glutathione S-transferase gene fusion system. The ATCase in B. cepacia has been previously classified as a class A enzyme by Bethell and Jones. ATCase activity gels show… more

Date: December 2004

Creator: Kim, Seongcheol

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Cyanide Assimilation in Pseudomonas Fluorescens: Characterization of Cyanide Oxygenase as a Pterin-Dependent Multicomponent Enzyme Complex

Cyanide utilization in Pseudomonas fluorescens NCIMB 11764 occurs via oxidative conversion to carbon dioxide and ammonia, the latter satisfying the nitrogen requirement. Substrate attack is initiated by an enzyme referred to as cyanide oxygenase (CNO), previously shown to require components in both high (H) (>30 kDa) and low (L) (<10 kDa) molecular weight cell fractions. In this study, tetrahydrobiopterin (H4biopterin) was identified as a cofactor in fraction L, thus making CNO appear as a pte… more

Access: Restricted to the UNT Community Members at a UNT Libraries Location.

Date: May 2004

Creator: Fernandez, Ruby

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Function of the ENOD8 gene in nodules of Medicago truncatula.

To elaborate on the function(s) of the ENOD8 gene in the nodules of M. truncatula, several different experimental approaches were used. A census of the ENOD8 genes was first completed indicating that only ENOD8.1 (nt10554-12564 of GenBank AF463407) is highly expressed in nodule tissues. A maltose binding protein-ENOD8 fusion protein was made with an E. coli recombinant system. A variety of biochemical assays were undertaken with the MBP-ENOD8 recombinant protein expressed in E. coli, which did … more

Date: December 2006

Creator: Coque, Laurent

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Applications of Molecular Genetics to Human Identity.

The primary objectives of this project were: 1. to develop improved methods for extraction of DNA from human skeletal remains, 2. to improve STR profiling success of low-copy DNA samples by employing whole genome amplification to amplify the total pool of DNA prior to STR analysis, and 3. to improve STR profiling success of damaged DNA templates by using DNA repair enzymes to reduce the number/severity of lesions that interfere with STR profiling. The data from this study support the following … more

Date: December 2008

Creator: Turnbough, Meredith A.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Identification of Genes Involved in Flocculation by Whole Genome Sequencing of Thauera aminoaromatica Strain MZ1T Floc-defective Mutants

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 sequ… more

Date: December 2015

Creator: Prombutara, Pinidphon

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Characterizing the Molecular Changes of Austrofundulus limnaeus As It Develops Towards and Enters Diapause II

Austrofundulus limnaeus is a species of annual killifish which inhabits ephemeral ponds in South America. The species is able to survive seasonally desiccating ponds due to their ability to produce robust embryos. The embryos of this species are capable of entering a developmental arrest, termed diapause II, which precedes the onset of drought. While in this arrested state embryos exhibit the greatest tolerance to anoxia of any characterized vertebrate at 25ºC. Furthermore, when raised at 30ºC,… more

Date: December 2015

Creator: Toni, Lee S.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Isolation and Genomic Characterization of 45 Novel Bacteriophages Infecting the Soil Bacterium Streptomyces griseus

Bacteriophages, or simply "phages," are the most abundant biological entities on the planet and are thought to be the largest untapped reservoir of available genetic information. They are also important contributors to both soil health and nutrient recycling and have significantly influenced our current understanding of molecular biology. Bacteria in the genus Streptomyces are also known to be important contributors to soil health, as well as producing a number of useful antibiotics. The geneti… more

Date: December 2018

Creator: Hale, Richard

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

The Effectiveness of Hybrid Problem-Based Learning versus Manual-Based Learning in the Microbiology Laboratory

Promising results from the use of problem-based learning (PBL) as a teaching method in medical programs have encouraged many institutions to incorporate PBL into their curricula. This study investigates how applying hybrid-PBL (H-PBL) in a microbiology laboratory impacts students' higher-order thinking as compared to applying a lecture-based pedagogy. The experimental design compared the learning outcomes of two groups of students: the control group and the H-PBL group, for whom PBL cases compr… more

Date: May 2017

Creator: Alharbi, Najwa

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Stress Response by Alternative σ-factor, RpoH, and Analysis of Posttranslational Modification of the Heat Shock Protein, Dnak, in Escherichia coli

Bacteria have developed specialized responses that involve the expression of particular genes present in a given regulon. Sigma factors provide regulatory mechanisms to respond to stress by acting as transcriptional initiation factors. This work focuses on σ32 during oxidative stress in Escherichia coli. The differential response of key heat shock (HS) genes was investigated during HS and oxidative stress using qPCR techniques. While groEL and dnaJ experienced increases in transcriptional respo… more

Date: May 2015

Creator: Martinez, Sarah N.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Construction of a Pseudomonas aeruginosa Dihydroorotase Mutant and the Discovery of a Novel Link between Pyrimidine Biosynthetic Intermediates and the Ability to Produce Virulence Factors

The ability to synthesize pyrimidine nucleotides is essential for most organisms. Pyrimidines are required for RNA and DNA synthesis, as well as cell wall synthesis and the metabolism of certain carbohydrates. Recent findings, however, indicate that the pyrimidine biosynthetic pathway and its intermediates maybe more important for bacterial metabolism than originally thought. Maksimova et al., 1994, reported that a P. putida M, pyrimidine auxotroph in the third step of the pathway, dihydroorot… more

Date: August 2003

Creator: Brichta, Dayna Michelle

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Characterization of the Outer Membrane of Treponema Pallidum Subsp. Pallidum by Binding Studies Using Antibodies, Complement, and Host Serum Proteins

The major goal of this study was to achieve sustained cultivation of virulent T. pallidum in vitro. The putatuive binding of host proteins to the outer membrane (OM) of intact, virulent T. pallidum subsp. pallidum has been investigated. A major breakthrough was the development of a filtration assay, usinglow protein-binding membrane filters, for the measurement of substances bound to or incorporated into th eOM of T. pallidum. This avoided the conventional manipulations which can damage the fra… more

Date: December 1989

Creator: Chang, Po-Hsun

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Cloacal Microbiota of Captive-bred and Wild Attwater’s Prairie-chicken, Tympanuchus Cupido Attwateri

The Attwater’s prairie-chicken (Tympanuchus cupido attwateri; APC) is a species of grouse native to Texas coastal prairies and is on the critically endangered species list as a result of habitat destruction and overhunting. All of the current populations were captively bred and released into the wild. Survivorship for released APCs is very low, and individuals seldom survive to reproduce in the wild. One factor contributing to this may be an alteration in the gut microbiota as a result of ca… more

Date: August 2014

Creator: Simon, Stephanie E.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

A Novel Mechanism for Site-Directed Mutagenesis of Large Catabolic Plasmids Using Natural Transformation

Natural transformation is the process by which cells take up DNA from the surrounding medium under physiological conditions, altering the genotype in a heritable fashion. This occurs without chemical or physical treatment of the cells. Certain Acinetobacter strains exhibit a strong tendency to incorporate homologous DNA into their chromosomes by natural transformation. Transformation in Acinetobacter exhibits several unique properties that indicate this system's superiority as a model for tra… more

Date: August 2001

Creator: Williamson, Phillip C.

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Establishing genetic and physiological baselines for the black-tailed prairie dog (Cynomys ludovicianus).

The black-tailed prairie dog (Cynomys ludovicianus) has experienced dramatic declines over much of its historical range due to habitat loss, plague, poisonings, and shootings. Many populations now occur as isolated genetic relicts. A multiple locus genetic profile was obtained using microsatellite analyses of six polymorphic nucleotide repeats from 319 black-tailed prairie dogs collected from 16 colonies throughout the state of Texas. This assessment revealed that existing populations have suff… more

Date: May 2007

Creator: Biggs, Cindy Dawn

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Comparative Biochemistry and Evolution of Aspartate Transcarbamoylase from Diverse Bacteria

Aspartate transcarbamoylase (ATCase) catalyzes the first committed step in pyrimidine biosynthesis. Bacterial ATCases are divided into three classes, A, B and C. Class A ATCases are largest at 450-500, are. dodecamers and represented by Pseudomonas ATCase. The overlapping pyrBC' genes encode the Pseudomonases ATCase, which is active only as a 480 kDa dodecamer and requires an inactive pyrC'-encoded DHOase for ATCase activity. ATCase has been studied in two non-pathogenic members of Mycobacteriu… more

Date: May 1999

Creator: Hooshdaran, Massoumeh Ziba

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Preparation and Characterization of Model Conjugates for the Study of Proteins Modified by ADP-ribose

Modification of proteins by ADP-ribose has been shown to be a versatile modification with respect to the amino acid side chain. The results described here will allow the study of the biological importance of ADP-ribose glycation and also allow differentiation on crude extracts between enzymatic modifications from protein ADP-ribose glycation that can occur due to the presence of NAD glycohydrolases.

Date: August 1992

Creator: Cervantes-Laurean, Daniel

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Discovery and Characterization of Two Tn5 Generated pyrA Mutants in Pseudomonas putida and the Generation of Hfr Strains

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

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Biochemical Identification of Molecular Components Required for Cyanide Assimilation in Pseudomonas fluorescens NCIMB 11764

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

Item Type: Thesis or Dissertation

Partner: UNT Libraries