UNT Libraries - 202 Matching Results

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N-Acylethanolamine Metabolism During Seed Germination: Molecular Identification of a Functional N-Acylethanolamine Amidohydrolase

Description: N-Acylethanolamines (NAEs) are endogenous lipid metabolites that occur in a variety of dry seeds, and their levels decline rapidly during the first few hours of imbibition (Chapman et al., 1999, Plant Physiol., 120:1157-1164). Biochemical studies supported the existence of an NAE amidohydrolase activity in seeds and seedlings, and efforts were directed toward identification of DNA sequences encoding this enzyme. Mammalian tissues metabolize NAEs via an amidase enzyme designated fatty acid amide hydrolase (FAAH). Based on the characteristic amidase signature sequence in mammalian FAAH, a candidate Arabidopsis cDNA was identified and isolated by reverse transcriptase-PCR. The Arabidopsis cDNA was expressed in E. coli and the recombinant protein indeed hydrolyzed a range of NAEs to free fatty acids and ethanolamine. Kinetic parameters for the recombinant protein were consistent with those properties of the rat FAAH, supporting identification of this Arabidopsis cDNA as a FAAH homologue. Two T-DNA insertional mutant lines with disruptions in the Arabidopsis NAE amidohydrolase gene (At5g64440) were identified. The homozygous mutant seedlings were more sensitive than the wild type to exogenously applied NAE 12:0. Transgenic seedlings overexpressing the NAE amidohydrolase enzyme showed noticeably greater tolerance to NAE 12:0 than wild type seedlings. These results together provide evidence in vitro and in vivo for the molecular identification of Arabidopsis NAE amidohydrolase. Moreover, the plants with altered NAE amidohydrolase expression may provide new tools for improved understanding of the role of NAEs in germination and seedling growth.
Date: August 2004
Creator: Shrestha, Rhidaya

Analysis and expression of the cotton gene for the D-12 fatty acid desaturases 2-4 (FAD2-4)

Description: A genomic clone containing a 16.9-kb segment of cotton DNA was found to encompass a D-12 fatty acid desaturases (FAD2-4) gene. The FAD2-4 gene has a single, large intron of 2,780 bp in its 5'-untranslated region, just 12 bp upstream from the ATG initiation codon of the FAD2-4 opening reading frame. A number of prospective promoter elements, including several light-responsive sequences, occur in the 5'-flanking region. The coding region of the gene is 1155 bp with no introns, and would encode a FAD2-4 polypeptide of 384 amino acids. The putative protein had four membrane-spanning helices, hallmarks of an integral membrane protein, and would probably be located in the endoplasmic reticulum. The FAD2-4 gene is indeed a functional gene, since yeast cells transformed with a plasmid containing the coding region of the gene synthesize an appreciable amount of linoleic acid (18:2), not normally made in wild-type yeast cells. The FAD2-4 gene has many structural similarities to the cotton FAD2-3 gene that was also analyzed in this laboratory.
Date: August 2003
Creator: Park, Stacy J.

Animal Contribution to Human Medicine

Description: The use of animal models in research has led to a fierce debate between animal rights activists and scientists. The former claim that little useful information is gained from animal studies and the suffering of animals does not preclude any treatments which may be used to treat human illnesses. Yet, research scientists claim that in vivo animal models are of absolute necessity to developing treatments and cures to disease. To determine the necessity of animal use, one must examine the models currently in research. Have the animal models for disorders such as cystic fibrosis and muscular dystrophy given scientists enough information to develop effective treatments? This paper will examine the role of animal subjects in several disease research protocols, as well as the applicability of the research.
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Date: May 2001
Creator: Kvernes, Kayce

Adherence and Haemagglutination of Moraxella Catarrhalis.

Description: M. catarrhalis is a gram-negative diplococci frequently associated with infections of the upper respiratory tract. During the past decade, some preliminary studies have attempted to elucidate mechanisms of adherence and haemagglutination of M. catarrhalis. These studies have reported, in many cases, inconsistent results. There are two purposes of this research. First, identify mechanisms that may potentially be associated with the adherence and haemagglutination of M. catarrhalis. Second, suggest research directions that may be fruitful in clarifying these mechanisms.
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Date: August 2000
Creator: Kosterman, Edward, III

The aquatic insect communities of Holbrook Creek and Cochetopa Creek in Colorado.

Description: The first objective for this problem in lieu of thesis project was to gather, identify to the lowest practical taxonomic level and organize all available aquatic insects collected from high altitude Colorado aquatic systems during the summers of 1994, 1996, 1998, and 2002 for the University of North Texas Environmental Science Field Course (BIOL 5650). The curated collection will be housed in the Elm Fork Natural History Museum, located at the University of North Texas. The second objective was to provide a summary and discussion of the occurrence and distribution of the aquatic insects collected from Mt. Blanca in 1994, 1996, and 1998 and to create a taxa list of aquatic insects collected from Cochetopa Creek during the summer of 2002.
Date: December 2003
Creator: Wallace, Mark Allen

Inherent Problems Associated with the Identification of Genes Responsible for Allowing B. cepacia to Adhere to Human Lung Carcinoma A549 Cells

Description: In this project a bacteria's ability to bind to human lung tissue was investigated. To carry out this study Pseudomonas aeruginosa, Eschericia coli and Burkholderia cepacia were used. B. cepacia served as the bacterium of interest. Isolating the gene which confers upon this bacterium the ability to bind to lung tissue was the main objective of this study. P. aeruginosa has been identified as being the bacteria most responsible for causing serious lung infections that can result in cystic fibrosis. This bacterium therefore served as the positive control in this study. On the contrary, E. coli does not possess this binding ability and served as the negative control. This paper gives a detailed outline of the different procedures necessary for the successful completion of this project. Firstly, a broad guideline of the important steps involved are explored. This is followed by a discussion on potential problems and possible solutions. Throughout the document, illustrations of expected results are indicated so as to further guide the researcher.
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Date: May 2001
Creator: Nesty, Gilda S.

Bioreactor Landfill Cell Feasibility Study ' Reference to City of Denton Subtitle-D Permit #1590A Landfill

Description: The City of Denton Landfill, Permit #1590A, utilizes “Dry-Tomb” techniques for disposal and promotion of municipal solid waste stabilization, as described by the Resource Conservation and Recovery Act (RCRA) prohibition in 40 CFR. Bioreactor research suggests re-circulating leachate increases biodegradation rates and reduces long-term monitoring from fifty years to less than ten years. Current procedures that are followed at Denton's landfill, literature review and the use of the Hydrologic Evaluation of Landfill Performance (HELP) model, suggest that a bioreactor landfill cell is worthy of further research. Re-circulating leachate and augmenting it with additional liquid will increase biodegradation and the need to design and build a landfill gas collection system to capture methane for energy recovery uses.
Date: May 2002
Creator: Roberts, Elizabeth

Dissolved Organic Carbon Assessment on Selected Creeks and Rivers within the Elmfork Subwatersheds of Denton, Texas

Description: The primary focus of the study was to compare dissolved organic carbon (DOC) at baseline stream flow to DOC at a higher post-rain stream flow, with a secondary focus on comparison of DOC between sites. Comparisons were also done on suspended solids at baseline flow to those of the higher post-rain flow, as well as suspended solids between sites. Significant differences did exist between DOC sampled at baseline flow and DOC in samples taken at peak flow. The study found no difference in suspended solids among sites neither on either baseflow sampling nor on the post rain event sampling.
Date: May 2004
Creator: Jackson, Pamela J.

Genetic Mechanisms for Anoxia Survival in C. Elegans

Description: Oxygen deprivation can be pathological for many organisms, including humans. Consequently, there are several biologically and economically relevant negative impacts associated with oxygen deprivation. Developing an understanding of which genes can influence survival of oxygen deprivation will enable the formulation of more effective policies and practices. In this dissertation, genes that influence adult anoxia survival in the model metazoan system, C. elegans, are identified and characterized. Insulin-like signaling, gonad function and gender have been shown to influence longevity and stress resistance in the soil nematode, C. elegans. Thus, either of these two processes or gender may influence anoxia survival. The hypothesis that insulin-like signaling alters anoxia survival in C. elegans is tested in Aim I. The hypotheses that gonad function or gender modulates anoxia survival are tested in Aim II. Insulin-like signaling affects anoxia survival in C. elegans. Reduction of insulin-like signaling through mutation of the insulin-like receptor, DAF-2, increases anoxia survival rates in a gpd-2/3 dependent manner. The glycolytic genes gpd-2/3 are necessary for wild-type response to anoxia, and sufficient for increasing anoxia survival through overexpression. Gonad function and gender both affect anoxia survival in C. elegans. A reduction of ovulation and oocyte maturation, as measured by oocyte flux, is associated with enhanced anoxia survival in all cases examined to date. Reduction of function of several genes involved in germline development and RTK/Ras/MAPK signaling reduce ovulation and oocyte maturation while concurrently increasing anoxia survival. The act of mating does not influence anoxia survival, but altering ovulation through breeding or chemical treatment does. The male phenotype also increases anoxia survival rates independent of genotype. These studies have identified and characterized over ten different genotypes that affect adult survival of anoxia in C. elegans. Before these studies were conducted, there were no genes known to influence adult anoxia survival in C. ...
Date: August 2008
Creator: Mendenhall, Alexander R.

A Contravention of Established Principles of Interspecific Allometric Metabolic Scaling in Developing Silkworms, Bombyx Mori.

Description: Established interspecific metabolic allometric relationships do not adequately describe the complexity and variable physiological states of developing animals. Consequently, intraspecific allometric relationships of oxygen consumption and carbon dioxide production as a function of body mass; the respiratory quotient; the function of the silk cocoon; and body composition were investigated for each distinct developmental stage of the silkworm, Bombyx mori. Whole animal O2 consumption in Bombyx ranged from 0.00064 + 0.000047 ml O2 .hr-1 at larval instar I to 0.77 + 0.06 ml O2 .hr-1 in pre-pupal, falling to 0.21+ 0.01 ml O2 .hr-1 in the pupae. Those instars having a significant relationship between O2 consumption as a function of body mass, the slope of the line relating O2 consumption to body mass varied between 0.99 and 1.02, while across all instars the slope was 0.82. Developmental allometry should be presented for individual developmental stages because the individual allometric exponents of the stages can be significantly different from the overall allometric exponent throughout development and in some cases, the overall allometric exponent can be a statistical artifact. The first larval instar of Bombyx mori has the lowest cross sectional area of high metabolic tissue of the midgut (27%) and had one of the highest percentages of some metabolically inert tissues (i.e. lipid, 7.5%). Body composition of the first instar does not support the idea that smaller mass animals having the highest O2 consumption are composed of a greater percentage of metabolically active organs when compared to larger animals. However, this developmental stage has the highest percentage of the mitochondrial marker cytochrome oxidase, which correlates well with the high O2 consumption rate of the smaller mass. Therefore, established interspecific principles should not be assumed to function as valid models for intraspecific developmental relationships of metabolism as a function of body mass. Developmental ...
Date: May 2007
Creator: Blossman-Myer, Bonnie

Correspondence Between Aquatic Ecoregions and the Distribution of Fish Communities of Eastern Oklahoma

Description: I assessed fish community data collected by the Oklahoma Conservation Commission from 82 minimally impaired wadeable reference streams in eastern Oklahoma to determine whether existing aquatic ecoregions provide the best framework for spatial classification for the development of biological assessment methods and biocriteria. I used indirect ordination and classification to identify groups of sites that support similar fish communities. Although correspondence was observed between fish assemblages and three montane ecoregions, the classification system must be refined and expanded to include major drainage basins and physical habitat attributes for some areas to adequately partition variance in key measures of biological integrity. Results from canonical correspondence analysis indicated that substrate size and habitat type were the primary physical habitat variables that influenced the fish species composition and community structure.
Date: May 2001
Creator: Howell, Charles E.

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

Description: 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 pterin- dependent hydroxylase. CNO was purified 150-fold (specific activity 0.9 U/mg) and quantitatively converted cyanide to formate and ammonia as reaction products. When coupled with formate dehydrogenase, the complete enzymatic system for cyanide oxidation to carbon dioxide and ammonia was reconstituted. CNO was found to be an aggregate of known enzymes that included NADH oxidase (Nox), NADH peroxidase (Npx), cyanide dihydratase (CynD) and carbonic anhydrase (CA). A complex multi-step reaction mechanism is proposed in which Nox generates hydrogen peroxide which in turn is utilized by Npx to catalyze the oxygenation of cyanide to formamide accompanied by the consumption of one and two molar equivalents of oxygen and NADH, respectively. The further hydrolysis of formamide to ammonia and formate is thought to be mediated by CynD. The role of H4biopterin and of the enzyme CA in the proposed process remains unclear, but the involvement of each in reactive oxygen and radical chemistry is consistent with the proposed formation of such species in the catalytic process. H4biopterin may additionally serve as a protein stabilizing agent along with a protein co-purifying with CynD identified as elongation factor Tu, a known chaperone. At least two of the CNO components (Nox and CynD) are complex oligomeric proteins whose apparent association with Npx and CA appears to be favored in bacterial cells induced with cyanide allowing their purification in toto as a ...
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Date: May 2004
Creator: Fernandez, Ruby

Developmental Patterns of Metabolism and Hematology in the Late Stage Chicken Embryo (Gallus Domesticus) at Two Incubation Temperatures.

Description: How temperature affects physiological development in the chicken embryo is unknown. Embryos incubated at 38°C or 35°C showed no difference in growth or survival. The time to hatching was longer in 35°C than 38°C embryos (23.7 vs. 20.6 days), but unaffected was the relative timing of appearance of developmental landmarks (internal, external pipping). At stage 43-44, 38°C embryos maintained oxygen consumption around 1 mL/g/h despite acute temperature reduction (suggesting thermoregulatory maturation), unlike 35°C embryos. In 35°C embryos the lower oxygen-carrying capacity and temperature insensitive blood O2 affinity (P50 about 30 mmHg) may restrict O2 delivery to tissues, limiting metabolism during decreased ambient temperature. Reduced incubation temperature retards normal hematological and thermoregulatory development.
Date: May 2003
Creator: Black, Juli

The Developmental Physiology of the Zebrafish: Influence of Environment and Cardiovascular Attributes

Description: Temperature effects on the development of the zebrafish embryos and larvae and adults were examined. It was found that the earlier in development a temperature change was performed on an embryo, the more significant the change in survival and/or subsequent development. Thus, viable temperature ranges for zebrafish widened significantly as development proceeded. Adults reared and bred at 25oC produced embryos that were significantly more successful at the lower range of rearing temperatures compared to embryos produced from adults reared at 28oC. The majority of this study focused on the physiological effects of swim training during development in the zebrafish. The earlier in development the zebrafish larvae were trained, the greater the mortality. Trained free swimming larvae had a significantly higher routine oxygen consumption after 11 days of training, and a higher mass specific routine metabolic rate after 8 and 11 days of training. Trained free swimming larvae consumed significantly less oxygen during swimming and were more efficient at locomotion, compared to control larvae. Training enhanced survival during exposure to extreme hypoxia in all age groups. Performance aspects of training were investigated in attempt to quantify training effects and in most cases, trained fish performed significantly better than controls. As blood vessels formed during development, they decreased in cross sectional area from days two to six. It was also shown that the variability in visual stroke volume measurements could be reduced significantly by using a third dimension in the analysis with a more accurate volume equation. Finally, the ontogeny of cardiac control was evaluated. The adrenergic receptors were the first to respond to pharmacological stimulation but were closely followed by cholinergic pharmacological stimulation a few days later. There was a significant cholinergic tone present in day 15 zebrafish larvae which persisted. Although an adrenergic tone was not documented in this study, ...
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Date: August 2001
Creator: Bagatto, Brian

Development of a Real-time Pcr Assay for the Detection of Campylobacter Jejuni and Campylobacter Coli.

Description: Campylobacter organisms are the most commonly reported bacterial causes of foodborne infection in the world, with Campylobacter jejuni and Campylobacter coli responsible for over 99% of reported infections. Traditionally, Campylobacter species detection is an arduous process, requiring a special incubation environment as well as specific growth media for an extended growth period. The development of a rapid and reliable diagnostic tool for the detection of Campylobacter species would be a valuable aid to the medical diagnostic decision process, especially to rule out Campylobacter infection during the enteric pre-surgical time period. Improved patient outcomes would result if this rapid assay could reduce the number of enteric surgeries. Assays performed during this dissertation project have demonstrated that both SYBR® green and hydrolysis probe assays targeting an 84 nucleotide portion of cadF, a fibronectin-binding gene of Campylobacter jejuni and Campylobacter coli, were able to detect from 101 to 108 copies of organism from stool specimens, did not detect nonspecific targets, and exhibited a coefficient of variation (CV) of 1.1% or less. Analytical validation of sensitivity, specificity and precision, successfully performed in these studies, warrants additional clinical validation of these assays.
Date: May 2009
Creator: Lewis, Sally

Development of a Procedure to Evaluate Groundwater Quality and Potential Sources of Contamination in the East Texas Basin

Description: This study contributes a procedure, based on data analysis and geostatistical methods, to evaluate the distribution of chemical ratios and differentiate natural and anthropogenic contaminant sources of groundwater quality in the East Texas Basin. Four aquifers were studied, Sparta, Queen City, Carrizo and Wilcox. In this study, Carrizo- Wilcox is considered as one aquifer, and Sparta-Queen City as another. These aquifers were divided into depth categories, 0-150 feet for Sparta-Queen City and 300-600 feet and 600-900 feet for Carrizo-Wilcox in order to identify individual sources of contamination. Natural sources include aquifer mineral make up, salt domes and lignite beds. Major anthropogenic sources include lignite and salt dome mining and oil-gas production. Chemical ratios selected were Na/Cl, Ca/Cl, Mg/Cl, SO4/Cl, (Na+Cl)/TDS, SO4/Ca and (Ca+Mg)/(Na+K). Ratio distributions and their relationships were examined to evaluate physical-chemical processes occurring in the study area. Potential contaminant sources were used to divide the Basin into three areas: Area 1 to the east, Area 2 in the west and Area 3 in the center. Bivariate analysis was used to uncover differences between the areas. The waters in Area 1 are potentially impacted primarily from oil field waters. Sources present in Area 2 include lignite beds and oil field operations. Area 3 is the cap rock of salt domes that can contain gypsum and anhydrite. Based on the exploratory data analysis (Na+Cl)/TDS, (Ca+Mg)/(Na+K), and SO4/Ca ratios were chosen for geostatistical analysis. Chemical ratios that provided indications of cation exchange, salt domes and oil fields were (Na+Cl)/TDS, (Ca+Mg)/(Na+K) and SO4/Ca. In the Sparta-Queen City 150 zone the procedure did not provide a good method for differentiating between contaminant sources. However, the procedure was effective to indicate impacted ground water in the Carrizo-Wilcox 600 and 900 foot zones.
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Date: May 2001
Creator: Alderman, John H.

Dna Profiling of Captive Roseate Spoonbill (Ajaia Ajaja) Populations As a Mechanism of Determining Lineage in Colonial Nesting Birds.

Description: Roseate spoonbills are colonial nesting birds with breeding grounds extending from the United States Gulf coast to the pampas of Argentina. The U.S. population suffered a severe bottleneck from 1890 to 1920. The population's recovery was slow and partially credited to migrations from Mexican rookeries, but a gene pool reduction would be expected. Five polymorphic Spoonbill autosomal short tandem repeat (STR) loci [three (GAT)n, one (AAAG)n and one (GT)n] and one Z/W-linked microsatellite exhibiting sex-specific dimorphism were isolated and characterized. The Z/W-linked STR locus accurately confirmed the sex of each bird. Allelic profiles for 51 spoonbills obtained from Dallas (Texas), Fort Worth (Texas) and Sedgwick County (Kansas) zoos revealed a non-continuous distribution of allele frequencies, consistent with the effects of a population bottleneck. Allelic frequencies also differed significantly between the isolated zoo populations. Although extra-pair copulations were suspected and difficult to document, zoos commonly used observational studies of mating pairs to determine familial relationships among adults and offspring. STR parentage analysis of recorded family relationships excluded one or both parents in 10/25 cases studied and it was further possible to identify alternative likely parents in each case. Mistaken familial relationships quickly lead to the loss of genetic variability in captive populations. Here, a decreased heterozygosity (HO) in 2nd generation captive-bred birds was observed at 3 out of 4 loci evaluated. Although these results could not be statistically validated because of the small number of individuals available for study (15 wild birds with no offspring vs. eight 2nd generation captive birds), they are considered biologically important, as decreased HO is an indicator of inbreeding and this apparent decrease occurred within two generations of removal from the wild. Collectively, the evidence obtained from this study suggests that captive spoonbill populations are experiencing rapid loss of diversity from an already depleted wild gene ...
Date: May 2002
Creator: Sawyer, Gregory M.

Effects of Triclosan, Triclocarban, and Caffeine Exposure on the Development of Amphibian Larvae.

Description: Triclosan and triclocarban are antimicrobials found in numerous consumer products, while caffeine is the most commonly consumed stimulant by humans. This study was undertaken to determine the effects of triclosan, triclocarban, and caffeine on the development and physiology of amphibian larvae. LC50 values of triclosan and triclocarban were determined after 96 hours for three North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a common amphibian developmental model: Xenopus laevis. Amphibian larvae were most sensitive to triclosan and triclocarban exposure during early development based upon 96-hour LC50 values. Heart rates for X. laevis and North American larvae exposed to triclosan were variable throughout development. However, significantly lower heart rates were observed in all larvae exposed to triclocarban. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to triclosan were significantly affected in larvae exposed to ½ LC50 and the LC50 concentration. Metabolic rates of X. laevis larvae exposed to triclocarban were significantly affected by exposure to ½ LC50 concentrations in three of four stages investigated. No significant differences were observed in North American larvae exposed to triclocarban. Tissue uptake, lipid uptake, tissue bioconcentration factor (BCF) and lipid BCF of triclosan and triclocarban were investigated in three developmental stages of X. laevis, and in one developmental stage of B. woodhousii woodhousii, and R. sphenocephala. For most tissue and lipid uptake values, a significant increase was observed as exposure concentration increased. Tissue and lipid BCF values were dependent upon both stage and species. Chronic and acute effects of caffeine were determined in X. laevis larvae. Acute 96-hour LC50 values in four developmental stages were > 75,000 ug L-1 caffeine and heart rates were significantly different at the two earliest developmental stages. Larvae chronically exposed to caffeine reached metamorphosis at the same time as controls. Changes in ...
Date: August 2009
Creator: Palenske, Nicole Marie

Effects of Methanol, Atrazine, and Copper on the Ultrastructure of Pseudokirchneriella Subcapitata (Selenastrum Capricornutum).

Description: The toxicity of methanol, atrazine, and copper to Pseudokirchneriella subcapitata (Korshikov) Hindák historically referred to as Selenastrum capricornutum Printz were determined following 96 hrs growth in a modified Goram's growth media. Methanol and atrazine inhibited fluorescence readings in the cultures by 50% (IC50) at concentrations of 2% and 82 µg/l respectively. These toxicity values compared favorably to other published reports. The IC50 for copper was 160 µg/l which is substantially higher than reported values. This is understandable because of the high chelating capacity of Goram's media. The use of stereologically derived relative volume in the chloroplasts, mitochondria, lipid bodies, phosphate bodies, and nucleus was investigated to determine if it could be used as a sensitive endpoint in toxicity tests. The volume fractions for the chloroplasts and mitochondria were normally distributed in control cells while the nuclei, phosphate bodies, and lipid bodies were not. The chloroplasts were the most dominate organelle occupying a mean relative volume of 46% and mitochondria occupied a mean relative volume of 3%. The nucleus and phosphate bodies occupied a median relative volume of 7% and 2% respectively. The lipid bodies were rare in section profile and no meaningful median relative volume could be calculated. Up to the 82nd percentile of sectioned profiles contained no recognizable lipid bodies. The use of relative volume was not a sensitive endpoint for use in toxicity tests. No significant differences in relative volume could be detected in the nucleus or phosphate bodies following any treatment. Limited differences were detected in the mitochondria, chloroplasts, and lipid bodies. The only significant differences that appear to be biologically significant occurred in methanol treated cells where an increase in the lipid bodies' relative volume was apparently concentration dependent. Significant differences in the relative volume of mitochondria and chloroplasts do not appear to be biologically significant.
Date: May 2004
Creator: Garrett, David C.

A Novel Phytoestrogen that Acts as an Agonist for Human Estrogen Receptors.

Description: Estrogen is the natural agonist of the estrogen receptor (ER). However, certain plant-derived compounds or phytoestrogens have been identified that mimic estrogens and act as agonists and/or antagonists of ERs, depending on subtype and target tissue. Understanding how phytoestrogens interact with ERs, and therefore effect the estrogenic response, may prove beneficial in hormone replacement therapy and in the prevention and treatment of hormone-related diseases. Using Thin Layer Chromatography, gas chromatography/mass spectrometry (GC/MS), and proton nuclear nagnetic resonance (HNMR), I identified 4-ethoxymethylphenol (4EM) found in Maclura pomifera. While most phytoestrogens are heterocyclic compounds, 4EM is a simple phenol that acts as an agonist of ER-alpha and -beta in HeLa and MCF-7 cells. To study the effect of 4EM on ER-alpha and -beta activity, I performed transient transfection assays and showed that 4EM activates ER dependent gene transcription in a dose dependent manner in both ER subtypes. Further, 4EM- mediated transcription in ER-alpha, like estrogen, was enhance in the presense of co-activators, SRC-1 (steroid receptor coactivator-1), CBP (CREB binding proteins), and E6-AP (E6-associated protein) and inhibited by trans-4- hydroxytamoxifen (4HT). I found that 4EM was specific for ER and did not activate transcription of the progesterone receptor in HeLa cells.
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Date: December 2001
Creator: Pearce, Virginia

N-Acylethanolamine (NAE) Profiles Change During Arabidopsis Thaliana Seed Germination and Seedling Growth

Description: An understanding of the potential roles as lipid mediators of a family of bioactive metabolites called N-acylethanolamines (NAEs) depends on their accurate identification and quantification. The levels of 18C unsaturated NAEs (e.g. NAE18:2, NAE 18:3, etc.) in wild-type seeds (about 2000 ng/g fw) generally decreased by about 80% during germination and post-germinative growth. In addition, results suggest NAE-degradative fatty acid amide hydrolase (FAAH) expression does not play a major role in normal NAE metabolism as previously thought. Seedlings germinated and grown in the presence of abscisic acid (ABA), an endogenous plant hormone, exhibited growth arrest and secondary dormancy, similar to the treatment of seedlings with exogenous N­lauroylethanolamine (NAE12:0). ABA-mediated growth arrest was associated with higher levels of unsaturated NAEs. Overall, these results are consistent with the concept that NAE metabolism is activated during seed germination and suggest that the reduction in unsaturated NAE levels is under strict temporal control and may be a requirement for normal seed germination and post-germinative growth.
Date: August 2006
Creator: Wiant, William C.

Analysis and Development of Post Secondary Curriculum on Sustainability

Description: This thesis examines existing curricula at colleges and universities about sustainability and uses results to develop an introductory post secondary course curriculum. The proposed course is organized around three major elements - - science, philosophy, and economics - - all integral to understanding sustainability. Materials needed to teach the proposed 3-semester hour course including syllabus, teaching modules, transparencies, handouts, and exams were developed. Suggestions on how to teach a one-semester hour course on sustainability and a workshop on sustainability are also presented. The following research and curriculum development was a project established and funded by the Texas Energy Office, Renewable Resources and Sustainability Program.
Date: May 2000
Creator: White, Miki Machell

Aspartate Transcarbamoylase of Aeromonas Hydrophila

Description: This study focused on the enzyme, aspartate transcarbamoylase (ATCase) from A. hydrophila, a Gram-negative bacterium found in fresh water. The molecular mass of the ATCase holoenzyme from A. hydrophila is 310 kDa. The enzyme is likely composed of 6 catalytic polypeptides of 34 kDa each and 6 regulatory polypeptides of 17 kDa each. The velocity-substrate curve for A. hydrophila ATCase is sigmoidal for both aspartate and carbamoylphosphate. The Km for aspartate was the highest to date for an enteric bacterium at 97.18 mM. The Km for carbamoylphosphate was 1.18 mM. When heated to 60 ºC, the specific activity of the enzyme dropped by more than 50 %. When heated to 100 ºC, the enzyme showed no activity. The enzyme's activity was inhibited by ATP, CTP or UTP.
Date: December 2000
Creator: Higginbotham, Leah