UNT Theses and Dissertations - 101 Matching Results

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Genetic Modification of Fatty Acid Profiles in Cotton

Description: The industrial uses of cottonseed oil are limited by its fatty acid composition. Genetic modification of cotton lipid profiles using seed-specific promoters could allow cotton growers to produce valuable new oils in the seed without adverse effects on fiber quality and yield, therefore making this crop more commercially profitable. Transgenic cotton callus harboring a diverged fatty acid desaturase gene (FADX) from Momordica charantia was characterized for production of alpha-eleostearic aci… more
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Date: August 2005
Creator: Rommel, Amy A.
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Hindrance of the Myosin Power Stroke Posed by the Proximity to the Troponin Complex Identified Using a Novel LRET Fluorescent Nanocircuit

Description: A novel luminescence resonance energy transfer (LRET) nanocircuit assay involving a donor and two acceptors in tandem was developed to study the dynamic interaction of skeletal muscle contraction proteins. The donor transmits energy relayed to the acceptors distinguishing myosin subfragment-1 (S1) lever arm orientations. The last acceptor allows the detection of S1's bound near or in between troponin complexes on the thin filament. Additionally, calcium related changes between troponin T and my… more
Date: May 2007
Creator: Coffee Castro-Zena, Pilar G.
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Homologous Recombination in Q-Beta Rna Bacteriophage

Description: Q-Beta phage RNAs with inactivating insertion (8 base) or deletion (17 base) mutations within their replicase genes were transfected into Escherichia coli spheroplasts containing QB replicase provided in trans by a resident plasmid. Replicase-defective (Rep~) Q3 phage produced by these spheroplasts were unable to form plaques on cells lacking this plasmid. When individual Rep~ phage were isolated and grown to high titer in cells containing plasmid derived Q3 replicase, revertant Q3 phage (Rep')… more
Date: May 1992
Creator: Palasingam, Kampan
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Identification and Characterization of a Calcium/Phospholipid-Dependent Protein Kinase in P1798 Lymphosarcomas

Description: Calcium/phospholipid-dependent protein kinase (PKC) was partially purified from P1798 lymphosarcoma. Phospholipid-dependence was specific for phosphatidylserine. PKC phosphorylated Histone 1, with an apparent K_m of 14.1 μM. Chlorpromazine, a lipid-binding drug, inhibited PKC activity by 100%. Further studies were undertaken to establish analytical conditions which could be applied to the study of PKC in intact cells. The conditions included (1) determining optimum cell concentration for measur… more
Date: May 1984
Creator: Magnino, Peggy E. (Peggy Elizabeth)
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Identification and Characterization of an Arabidopsis thaliana Mutant with Tolerance to N-lauroylethanolamine

Description: N-Acylethanolamines (NAEs) are fatty acid derivatives in plants that negatively influence seedling growth. N-Lauroylethanolamine (NAE 12:0), one type of NAE, inhibits root length, increases radial swelling of root tips and reduces root hair numbers in a dose dependent manner in Arabidopis thaliana L. (ecotype Columbia). A forward genetics approach was employed by screening a population of T-DNA “activation-tagged” developed by the Salk Institute lines for NAE resistance to identify potential … more
Date: December 2015
Creator: Adhikari, Bikash
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Identification and quantification of lipid metabolites in cotton fibers: Reconciliation with metabolic pathway predictions from DNA databases.

Description: The lipid composition of cotton (Gossypium hirsutum, L) fibers was determined. Fatty acid profiles revealed that linolenate and palmitate were the most abundant fatty acids present in fiber cells. Phosphatidylcholine was the predominant lipid class in fiber cells, while phosphatidylethanolamine, phosphatidylinositol and digalactosyldiacylglycerol were also prevalent. An unusually high amount of phosphatidic acid was observed in frozen cotton fibers. Phospholipase D activity assays revealed that… more
Date: May 2004
Creator: Wanjie, Sylvia W.
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Identification of Endogenous Substrates for ADP-Ribosylation in Rat Liver

Description: Bacterial toxins have been shown to modify animal cell proteins in vivo with ADPR. Animal cells also contain endogenous enzymes that can modify proteins. Indirect evidence for the existence in vivo of rat liver proteins modified by ADPR on arginine residues has been reported previously. Presented here is direct evidence for the existence of ADP-ribosylarginine in rat liver proteins. Proteins were subjected to exhaustive protease digestion and ADP-ribosyl amino acids were isolated by boronate ch… more
Date: May 1992
Creator: Loflin, Paul T. (Paul Tracey)
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Identification of Three Symbiosome Targeting Domains in the MtENOD8 Protein and Cell-to-cell MtENOD8 mRNA Movement in Nodules

Description: The model legume, Medicago truncatula, is able to enter into a symbiotic relationship with soil bacteria, known as rhizobia. This relationship involves a carbon for nitrogen exchange in which the plant provides reduced carbon from photosynthesis in exchange for reduced, or “fixed” atmospheric nitrogen, which allows the plant to thrive in nitrogen depleted soils. Rhizobia infect and enter plant root organs, known as nodules, where they reside inside the plant cell in a novel organelle, known a… more
Date: May 2012
Creator: Meckfessel, Matthew Harold
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Identifying genetic interactions of the spindle checkpoint in Caenorhabditis elegans.

Description: Faithful segregation of chromosomes is ensured by the spindle checkpoint. If a kinetochore does not correctly attach to a microtubule the spindle checkpoint stops cell cycle progression until all chromosomes are attached to microtubules or tension is experienced while pulling the chromosomes. The C. elegans gene, san-1, is required for spindle checkpoint function and anoxia survival. To further understand the role of san-1 in the spindle checkpoint, an RNAi screen was conducted to identify gen… more
Date: May 2009
Creator: Stewart, Neil
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In Vitro Modulation of Rat Liver Glyoxalase II Activity

Description: Glyoxylase II (Glo II, E.C. 3.1.2.6) catalyzes the hydrolysis of S-D-Lactoylglutathione (SLG) to D-Lactate and glutathione. This is the rate limiting step in the conversion of methylglyoxal to D-Lactate. The purpose of the present study was to determine whether or not a relationship exists between some naturally occuring metabolites and in vivo modulation of Glo II. We have observed a non-competitive inhibition (~ 45%) of Glo II in crude preparation of rat liver by GTP (0.3 mM). A factor (appar… more
Date: August 1988
Creator: Mbamalu, Godwin E.
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Induced CSF-1 Production and its Effects on C-FMS Transfected Monoblastic U937 Cells

Description: This study examined how the monoblast-like human histiocytic lymphoma cell line U937 can be induced by phorbol 12-myristrate 13-acetate (PMA) to undergo differentiation. In order to study the mechanism of action of CSF-1, a CSF-1 receptor gene (c-fms) was transfected into U937 cells. Exogenous CSF-1 treatment induced an autocrine response in this CSF-1 was determined and all events were shown to be time dependent. CSF-1 stimulation also enhanced proto-oncogene c-jun and c-myc gene expression. … more
Date: August 1992
Creator: Liu, Mu-ya
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Interactions of N-Acylethanolamine Metabolism and Abscisic Acid Signaling in Arabidopsis Thaliana Seedlings

Description: N-Acylethanolamines (NAEs) are endogenous plant lipids hydrolyzed by fatty acid amide hydrolase (FAAH). When wildtype Arabidopsis thaliana seeds were germinated and grown in exogenous NAE 12:0 (35 µM and above), growth was severely reduced in a concentration dependent manner. Wildtype A. thaliana seeds sown on exogenous abscisic acid (ABA) exhibited similar growth reduction to that seen with NAE treatment. AtFAAH knockouts grew and developed similarly to WT, but AtFAAH overexpressor lines sh… more
Date: August 2010
Creator: Cotter, Matthew Q.
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Isolation and Characterization of Two Enzyme Proteins Catalyzing Oxido-Reduction at C-9 and C-15 of Prostaglandins from Swine Kidney

Description: Two swine kidney proteins (PI 4.8 and 5.8) both possessing 9-prostaglandin ketoreductase (9-PGKR) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) activities were purified to homogeneity. Purification increased specific activities in parallel. Molecular weight, subunit size, amino acid composition, coenzyme and substrate specificity and antigenicity of both proteins were similar. Gel filtration and SDS-polyacrylamide gel electrophoresis molecular weights of 29,500 and 29,000, respectively, s… more
Date: December 1980
Creator: Chang, David Guey-Bin
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Kinetic and Chemical Mechanism of 6-phosphogluconate Dehydrogenase from Candida Utilis

Description: A complete initial velocity study of the 6-phosphogluconate dehydrogenase from Candida utilis in both reaction directions suggests a rapid equilibrium random kinetic mechanism with dead-end E:NADP:(ribulose 5-phosphate) and E:NADPH:(6- phosphogluconate) complexes. Initial velocity studies obtained as a function of pH and using NAD as the dinucleotide substrate for the reaction suggest that the 2'-phosphate is critical for productive binding of the dinucleotide substrate. Primary deuterium isoto… more
Date: May 1993
Creator: Berdis, Anthony J. (Anthony Joseph)
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Kinetic and Chemical Mechanism of O-Acetylserine Sulfhydrylase-B from Salmonella Typhimurium

Description: Initial velocity studies of O-acetylserine sulfhydrylase-B (OASS-B) from Salmonella typhimurium using both natural and alternative substrates suggest a Bi Bi ping pong kinetic mechanism with double substrate competitive inhibition. The ping pong mechanism is corroborated by a qualitative and quantitative analysis of product and dead-end inhibition. Product inhibition by acetate is S-parabolic noncompetitive, indication of a combination of acetate with E followed by OAS. These data suggest some … more
Date: August 1993
Creator: Tai, Chia-Hui
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Kinetic and Chemical Mechanism of Pyrophosphate-Dependent Phosphofructokinase

Description: Data obtained from isotope exchange at equilibrium, exchange of inorganic phosphate against forward reaction flux, and positional isotope exchange of 18O from the (βγ-bridge position of pyrophosphate to a (β-nonbridge position all indicate that the pyrophosphate-dependent phosphofructokinase from Propionibacterium freudenreichii has a rapid equilibrium random kinetic mechanism. All exchange reactions are strongly inhibited at high concentrations of the fructose 6-phosphate/Pi and MgPPi/Pi subst… more
Date: December 1988
Creator: Cho, Yong Kweon
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Luminescence Resonance Energy Transfer-Based Modeling of Troponin in the Presence of Myosin and Troponin/Tropomyosin Defining Myosin Binding Target Zones in the Reconstituted Thin Filament

Description: Mechanistic details on the regulation of striated muscle contraction still need to be determined, particularly the specific structural locations of the elements comprising the thick and thin filaments. Of special interest is the location of the regulatory component, troponin, on the actin filament and how its presence influences the behavior of myosin binding to the thin filament. In the present study: (1) Luminescence resonance energy transfer was used to monitor potential conformational chang… more
Date: May 2009
Creator: Patel, Dipesh A.
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Manipulating Sucrose Proton Symporters to Understand Phloem Loading

Description: Phloem vascular tissues transport sugars synthesized by photosynthesis in mature leaves by a process called phloem loading in source tissues and unloading in sink tissues. Phloem loading in source leaves is catalyzed by Suc/H+ symporters (SUTs) which are energized by proton motive force. In Arabidopsis the principal and perhaps exclusive SUT catalyzing phloem loading is AtSUC2. In mutant plants harboring a T-DNA insertion in each of the functional SUT-family members, only Atsuc2 mutants demonst… more
Date: August 2013
Creator: Dasgupta, Kasturi
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Manipulations of Sucrose/Proton Symporters and Proton-pumping Pyrophosphatase Lead to Enhanced Phloem Transport But Have Contrasting Effects on Plant Biomass

Description: Delivery of photoassimilate, mainly sucrose (Suc) from photoautotrophic source leaves provides the substrate for the growth and maintenance of sink tissues such as roots, storage tissues, flowers and fruits, juvenile organs, and seeds. Phloem loading is the energized process of accumulating solute in the sieve element/companion cell complex of source leaf phloem to generate the hydrostatic pressure that drives long-distance transport. In many plants this is catalyzed by Suc/Proton (H+) symporte… more
Date: May 2015
Creator: Khadilkar, Aswad S
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Mechanism of Activation by Autophosphorylation of an S6/H4 Kinase Isolated From Human Placenta

Description: A novel molecular mechanism of autophosphorylation-dependent activation of the ser/thr S6/H4 kinase isolated from human placenta is described. Phosphopeptide mapping of the enzyme was used to determine the rate and extent of site-specific autophosphorylation. These data were correlated to phosphotransferase activity of the protein kinase. The results indicated that a sequential phosphorylation of two sites in the catalytic domain is required for maximum activation. Kinetic analysis determined t… more
Date: December 1994
Creator: Benner, Gretchen E. (Gretchen Evonne)
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Mechanism of the Adenosine 3',5'-Monophosphate Dependent Protein Kinase

Description: Isotope partitioning experiments were carried out with the adenosine 3',5'-monophosphate-dependent protein kinase catalytic subunit (cAPK) from bovine hearts to obtain information on the order of addition of reactants and the relative rates of reactant release from enzyme compared to the catalytic step(s). A value of 100% trapping for both ErMgATP-[γ-32P] and E:3H-Serpeptide at low Mgf indicates that MgATP and Serpeptide dissociate slowly from the enzyme compared to the catalytic step(s). The K… more
Date: May 1988
Creator: Kong, Cheng-Te
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Metabolic Engineering of Raffinose-Family Oligosaccharides in the Phloem Reveals Alterations in Patterns of Carbon Partitioning and Enhances Resistance to Green Peach Aphid

Description: Phloem transport is along hydrostatic pressure gradients generated by differences in solute concentration between source and sink tissues. Numerous species accumulate raffinose-family oligosaccharides (RFOs) in the phloem of mature leaves to accentuate the pressure gradient between source and sinks. In this study, metabolic engineering was used to generate RFOs at the inception of the translocation stream of Arabidopsis thaliana, which transports predominantly sucrose. To do this, three genes, … more
Date: August 2010
Creator: Cao, Te
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Metabolism of Diadenosine-5ʹ,5ʹʹʹ-P¹,P⁴-tetraphosphate (Ap₄A) in Cultured Mammalian Cells

Description: Methodology was developed which allowed the rapid and routine quantitation of subpicomole quantities of diadenosine-5ʹ,5ʹʹʹ-P¹,P⁴-tetraphosphate (Ap₄A) in cultured mammalian cells. This methodology includes the rapid extraction of cellular nucleotides in cold alkali, resolution of Ap₄A from the bulk of cellular materials on a highly specific boronate affinity resin, and quantitation of the dinucleotide in a coupled bioluminescence assay utilizing venom phosphodiesterase and firefly luciferase. … more
Date: December 1984
Creator: Baker, Jeffrey C. (Jeffrey Clayton)
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Modification of Cardiac Membrane Gsα by an Endogenous Arginine-Specific Mono-Adp-Ribosyltransferase

Description: The mechanism by which nicotinamide adenine dinucleotide (NAD) stimulates the activity of adenylate cyclase (AC) in canine plasma membrane has been studied. Using [3 2P]-NAD, the activation by NAD was correlated with the radiolabeling of the stimulatory guanosine triphosphate (GTP) binding protein Gsa. Further characterization demonstrated that the modification occurred only in the presence of G-protein activators and that arginine residue(s) were modified by ADP-ribose by the action of a mono-… more
Date: December 1993
Creator: Coyle, Donna L. (Donna Lynn)
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