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Assessing the Effects of a Municipal Wastewater Treatment Plant Effluent on Zooplankton, Phytoplankton and Corbicula Flumina in a Constructed Wetland

Description: Wetland wastewater treatment offers low-cost, energy efficient alternatives to conventional wastewater technologies. In this study, an artificial wetland was constructed at the City of Denton, Texas Pecan Creek Water Reclamation Plant to facilitate diazinon removal from treated effluent.
Date: May 1995
Creator: Hymel, Stephanie Ramick

Pyrimidine Metabolism in Rhizobium: Physiological Aspects of Pyrimidine Salvage

Description: The objective of this research was to study the pyrimidine salvage pathways of Rhizobium. Three approaches were used to define the pyrimidine salvage pathways operative in two species of Rhizobium, R. meliloti and R. leguminosarum . The first approach was to ascertain the pyrimidine bases and nucleosides that could satisfy the pyrimidine requirement of pyrimidine auxotrophs. Uracil, cytosine, uridine or cytidine all satisfied the absolute pyrimidine requirement. The second approach was to select for mutants resistant to 5-fluoropyrimidine analogues which block known steps in the interconversion of the pyrimidine bases and nucleosides. Mutants resistant to 5-fluorouracil lacked the enzyme uracil phosphoribosyltransferase (upp ) and could no longer use uracil to satisfy their pyrimidine requirement. Mutants resistant to 5-fluorocytosine, while remaining sensitive to 5- fluorouracil, lacked cytosine deaminase (cod) and thus could no longer use cytosine to satisfy their pyrimidine auxotrophy. The third approach used a reversed phase HPLC column to identify the products that accumulated when cytidine, uridine or cytosine was incubated with cell extracts of wild type and analogue resistant mutants of Rhizobium. When cytidine was incubated with cell extracts of Rhizobium wild type, uridine, uracil and cytosine were produced. This Indicated that Rhizobium had an active cytidine deaminase (cdd) and either uridine phosphorylase or uridine hydrolase. By dialyzing the extract and reincubating it with cytidine, uridine and uracil still appeared. This proved that it was a hydrolase ( nuh ) rather than a phosphorylase that degraded the nucleoside. Thus, Rhizobium was found to contain an active cytidine deaminase and cytosine deaminase with no uridine phosphorylase present. The nucleoside hydrolase was active with cytidine, uridine and to a far lesser extent with purines, adenosine and inosine. When high concentrations of cytidine were added to mutants devoid of hydrolase, cytosine was produced from cytidine - 5-monophosphate by the sequential action ...
Date: December 1989
Creator: Ibrahim, Mohamed M.

Histological age estimation of the midshaft clavicle using a new digital technique.

Description: Histological methods to estimate skeletal age at death, in forensic cases, are an alternative to the more traditional gross morphological methods. Most histological methods utilize counts of bone type within a given field for their estimation. The method presented in this paper uses the percentage area occupied by unremodeled bone to estimate age. The percentage area occupied by unremodeled bone is used in a linear regression model to predict skeletal age at death. Additionally, this method uses digital software to measure area rather than the traditional technique in which a gridded microscope is used to estimate area. The clavicle was chosen as a sample site since it is not a weight bearing bone and has little muscular insertion. These factors reduce the variation seen as a result of differences in lifestyle or activity pattern.
Date: August 2004
Creator: Ingraham, Mark R.

Biochemical Systematics of the Genus Sophora

Description: Three unusual amino acids, y-amino-n-butyric acid, pipecolic acid, and 4-hydroxypipecolic acid, and an uncommon dipeptide, y-glutamyltyrosine, have been isolated and characterized from the seeds of members of the genus Sophora. Structural proof of these compounds was carried out by paper chromatography, thin-layer chromatography, column chromatography on amino acid analyzer, infrared, nuclear magnetic resonance, mass spectrometry, and C, H, N analysis. The presence and absence of these compounds was used as a criterion for the classification of 23 species of the genus Sophora. A phylogenetic classification which seems to follow the morphological taxonomy of this genus was carried out on the basis of seeds that contained pipecolic acid, those which did not contain pipecolic acid, and plants which contained both pipecolic acid and 4-hydroxypipecolic acids. Another chemical classification was also introduced based on the presence and absence of y-amino-n-butyric acid and y-glutamyltyrosine.
Date: December 1973
Creator: Izaddoost, Mohamed

Residential Grid-Connected Photovoltaics Adoption in North Central Texas: Lessons from the Solarize Plano Project

Description: Residential Grid-Connected Photovoltaics (GPV) systems hold remarkable promise in their potential to reduce energy use, air pollution, greenhouse gas emissions, and energy costs to consumers, while also providing grid efficiency and demand-side management benefits to utilities. Broader adoption of customer-sited GPV also has the potential to transform the traditional model of electricity generation and delivery. Interest and activity has grown in recent years to promote GPV in north central Texas. This study employs a mixed methods design to better understand the status of residential GPV adoption in the DFW area, and those factors influencing a homeowner's decision of whether or not to install a system. Basic metrics are summarized, including installation numbers, distribution and socio-demographic information for the case study city of Plano, the DFW region, Texas, and the United States. Qualitative interview methods are used to gain an in-depth understanding of the factors influencing adoption for the Solarize Plano case study participants; to evaluate the effectiveness of the Solarize Plano program; and to identify concepts that may be regionally relevant. Recommendations are presented for additional research that may advance GPV adoption in north central Texas.
Date: August 2016
Creator: Jack, Katherine G.

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.

Use of GIS and Remote Sensing Technologies to Study Habitat Requirements of Ocelots, Leopardus pardalis, in south Texas

Description: The goals of this study were to use Geographic Information Systems (GIS) and remote sensing technologies to gain a better understanding of habitat requirements of a population of ocelots in south Texas, and then apply this knowledge to form a predictive model to locate areas of suitable habitat in Willacy and Cameron counties, Texas. Satellite imagery from August 1991 and August 2000 were classified into four land cover types: closed canopy, open canopy, water, and urban/barren. These classified images were converted into digital thematic maps for use in resource utilization studies and modeling. Location estimates (762 from 1991 and 406 from 2000) were entered into a GIS in order to extract information about home range and resource selection. Each animal's home range was calculated using both Minimum Convex Polygon (MCP) and Kernel home range estimators (95% and 50%). Habitat parameters of interest were: soil, land cover, human density, road density, and distance to closest road, city and water body. Ocelots were found to prefer closed canopy and avoid open canopy land cover types. Ocelots preferred soils known to support thorn scrub, an indication of the importance of this habitat. Landscape metrics associated with habitat used by ocelots were determined through the use of Patch Analyst, an extension for ArcView 3.2. Contrary to expectations, ocelots utilized areas with greater fragmentation than random areas available for use. However, this use of highly fragmented areas was an indication of the degree of fragmentation of suitable habitat in the area. Further investigation of patch size selection indicated that ocelots used large sized patches disproportionately to availability, indicating a preference for larger patches. A model was created using the resource selection and habitat preference GIS database from 1991. This model was used to identify areas of “optimal”, ”sub-optimal”, and “unsuitable” habitat for ocelots in 2000. ...
Date: August 2002
Creator: Jackson, Victoria L.

Classification of Toolmark Surfaces on Zipper Teeth

Description: This study proposes the classification of the toolmark under the heads of zipper teeth as a subclass characteristic as outlined by the Association of Firearm and Toolmark Examiners (AFTE). Two separate cases in which zipper teeth were found at crime scenes prompted this study. Brass zipper teeth manufactured by YKK were taken from 20 pairs of jeans and studied using a Reichert comparison microscope at 4X power. Photographs were taken and over 750 comparisons made. It was found that the toolmarks on each side on the 20 zippers were unique and independent of all other sides. The observations made in this study indicate that classifying zipper teeth toolmarks as a subclass characteristic is valid.
Date: December 1999
Creator: Jacobsen, Dawn

Comparative Toxicity of Refuse-Derived Fuel Fly Ash on Two Species of Earthworms, Lumbricus terrestris and E. foetida, Using an Artificial Soil Exposure Protocol

Description: Research estimated toxicity of refuse-derived fuel fly ash (RDF-FA) on two earthworms species, Lumbricus terrestris and Eisenia foetida. Specific objectives were to: (1) Compare their 14-day LC50s under light and dark conditions; (2) separate toxicity due to osmotic, pH and physical factors from that of heavy metal contaminants; (3) compare relative differences of artificial soil and commercial soil as exposure media for evaluating toxicity to earthworms. The 14-d LC50s for L. terrestris in dark and light were 57.0 and 48.34 % RDF-FA, and 59.25 and 41.00 % RDF-FA for E. foetida using artificial soil. All of the toxicity resulted from heavy metals within the RDF-FA. Using L. terrestris, the LC50s for artificial soil and commercial soil were 52.30 and 64.34%.
Date: May 1991
Creator: Jahani, Aghamolla

Influence of a Human Lipodystrophy Gene Homologue on Neutral Lipid Accumulation in Arabidopsis Leaves

Description: CGI-58 is the defective gene in the human neutral lipid storage disease called Chanarin-Dorfman syndrome. This disorder causes intracellular lipid droplets to accumulate in nonadipose tissues, such as skin and blood cells. Here, disruption of the homologous CGI-58 gene in Arabidopsis thaliana resulted in the accumulation of neutral lipid droplets in mature leaves. Mass spectroscopy of isolated lipid droplets from cgi-58 loss-of-function mutants showed they contain triacylglycerols with common leaf specific fatty acids. Leaves of mature cgi-58 plants exhibited a marked increase in absolute triacylglycerol levels, more than 10-fold higher than in wild-type plants. Lipid levels in the oil-storing seeds of cgi-58 loss-of-function plants were unchanged, and unlike mutations in beta-oxidation, the cgi-58 seeds germinated and grew normally, requiring no rescue with sucrose. We conclude that the participation of CGI-58 in neutral lipid homeostasis of nonfat-storing tissues is similar, although not identical, between plant and animal species. This unique insight may have implications for designing a new generation of technologies that enhance the neutral lipid content and composition of corp plants.
Date: August 2016
Creator: James, Christopher Neal

Effects of Ribavirin on Normal Rat Kidney Cells and Chicken Embryo Fibroblasts Infected with Rous Sarcoma Virus

Description: Ribavirin, a synthetic nucleoside, was found to inhibit the replication of Rous sarcoma viruses (RSV) and subsequent cell transformation in chick embryo fibroblasts (CEF). It also blocked the transformation of normal rat kidney (NRK) cells infected with temperature-sensitive mutants of RSV. The action of Ribavirin was found to be reversible as removal of the drug from the NRK cells reversed the effects on cell transformation. Ribavirin appears to have a static effect on cell growth of both NRK and CEF cells. In addition, guanosine, xanthosine and inosine altered the effect of Ribavirin on cell growth.
Date: April 1979
Creator: Jenkins, Frank J.

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

Measuring Atmospheric Ozone and Nitrogen Dioxide Concentration by Differential Optical Absorption Spectroscopy

Description: The main objective was to develop a procedure based on differential optical absorption spectroscopy (DOAS) to measure atmospheric total column of ozone, using the automated instrument developed at the University of North Texas (UNT) by Nebgen in 2006. This project also explored the ability of this instrument to provide measurements of atmospheric total column nitrogen dioxide. The instrument is located on top of UNT’s Environmental Education, Science and Technology Building. It employs a low cost spectrometer coupled with fiber optics, which are aimed at the sun to collect solar radiation. Measurements taken throughout the day with this instrument exhibited a large variability. The DOAS procedure derives total column ozone from the analysis of daily DOAS Langley plots. This plot relates the measured differential column to the airmass factor. The use of such plots is conditioned by the time the concentration of ozone remains constant. Observations of ozone are typically conducted throughout the day. Observations of total column ozone were conducted for 5 months. Values were derived from both DOAS and Nebgen’s procedure and compared to satellite data. Although differences observed from both procedures to satellite data were similar, the variability found in measurements was reduced from 70 Dobson units, with Nebgen’s procedure, to 4 Dobson units, with the DOAS procedure.A methodology to measure atmospheric nitrogen dioxide using DOAS was also investigated. Although a similar approach to ozone measurements could be applied, it was found that such measurements were limited by the amount of solar radiation collected by the instrument. Observations of nitrogen dioxide are typically conducted near sunrise or sunset, when solar radiation experiences most of the atmospheric absorption.
Date: December 2011
Creator: Jerez, Carlos J.

A Study of Polynuclear Aromatic Hydrocarbon Carcinogen Transport and Deoxyribonucleic Acid Repair

Description: This investigation addresses the interrelated problems of A) Uptake and vascular transport of lipophilic chemical carcinogens, and intracellular interactions between lipoproteins and carcinogens; B) Biochemical mechanisms by which polynuclear aromatic hydrocarbon carcinogens inhibit the replicative and repair DNA synthesis in cells. The results observed in this study suggest that ingested benzo(a)pyrene (BaP) enters the gastrointestinal lymphatic drainage sequestered within lymphatic lipoproteins, and that low-density lipoproteins (LDL) play a major role in the vascular transport of BaP. BaP is taken up into cells by adsorptive endocytosis mediated by an interaction between apolipoprotein-specific receptors on the cell membrane and the specific apolipoproteins on LDL. Having entered peripheral cells sequestered within the lipid core of LDL, an electrophilic metabolite of BaP covalently binds to cellular DNA, and may interact with other cellular macro-molecules. Data presented here suggest that LDL is also absolutely required for the activation of DNA polymerase-a, which is the major enzyme of DNA excision repair necessary to correct the DNA damage caused by BaP. This study concludes that an active metabolite of the polynuclear aromatic hydrocarbon carcinogen, benzo(a)pyrene, suppresses DNA polymerase-a activity by inhibiting the binding of 2'-deoxyguanosine 5'-triphosphate to an acceptor site on the DNA polymerase-a complex with the DNA substrate, thereby competitively inhibiting interaction of 2'-deoxyguanosine 5'-triphosphate in the DNA synthetic process.
Date: December 1984
Creator: Joe, Cheol O., 1949-

Use of In-Stream Water Quality Measurements and Geospatial Parameters to Predict Consumer Surfactant Toxic Units in the Upper Trinity River Watershed, Texas

Description: Surfactants are used in a wide assortment of "down-the-drain" consumer products, yet they are often discharged in wastewater treatment plant effluent into receiving water, potentially causing environmental harm. The objective of this project was to predict surfactant toxic units and in-stream nutrients in the upper Trinity River watershed. Surface and pore water samples were collected in late summer 2005. General chemistries and surfactant toxic units were calculated. GIS models of anthropogenic and natural factors were collected and analyzed according to subwatersheds. Multiple regression analyses using the Maximum R2 improvement method were performed to predict surfactant toxic units and in-stream nutrients using GIS and in-stream values. Both geospatial and in-stream parameters generated multiple regression models for surfactant surface and pore water toxic units, as well as in-stream nutrients, with high R2 values. Thus, GIS and in-stream parameter modeling have the potential to be reliable and inexpensive method of predicting surfactant toxic units and nutrient loading in the upper Trinity River watershed.
Date: May 2008
Creator: Johnson, David Richard

Home range analysis of rehabilitated and released great horned owls (Bubo virginianus) in Denton County, Texas, through radio telemetry.

Description: Raptor rehabilitation has become commonplace globally, yet studies on the survival and adaptation of great horned owls (Bubo virginianus) after release has been neglected to an appreciable extent. The primary objective of this study is to provide quantitative data on the success of rehabilitated and released great horned owls in the North Texas region. Owls (N=12) were rehabilitated and released onto the Ray Roberts Greenbelt Corridor in Denton County, Texas, and monitored using radio telemetry to evaluate home range (November 2002 - February 2005). With approximately 75% of the birds released for this study surviving until transmitter battery failure, it is believed that the rehabilitation process was successful for these birds.
Date: December 2007
Creator: Johnston, Jennifer Lynn

Hematological Parameters of the Bluegill, Lepomis machrochirus (Rafinesque), Including Effects of Turbidity, Chloramines, and Flexibacter columnaris

Description: Normal ranges of values for hematological parameters of bluegill gathered seasonally from three lakes were determined. Sexual, seasonal, and inter-lake variations were found. Effects of 2-wk exposure to turbidity on blood parameters included an increase in rbc size and a decrease in small lymphocytes. Effects of 3-hr exposure were increases in rbc count, hemoglobin, and pH and decreases in PG2 and large lymphocytes. The effects of 0.44 and 0.88 ppm chloramines were an increase in blood pH, a decrease in MEV, and severe spastic reactions resulting in loss of equilibrium or death in 90% of the fish. Effects of Flexibacter columnaris included an increase in transformed lymphocytes and a decrease in small lymphocytes.
Date: May 1976
Creator: Jones, Betty Juanelle

Phenotypic Morphological Plasticity Induced by Environmental Salt Stress in the Brine Shrimp, Artemia franciscana

Description: Phenotypic plasticity is the ability of an organism to express different phenotypes in response to biotic or abiotic environmental cues. The ability of an organism to make changes during development to adjust to changes in its environment is a key to survival. Sexually reproducing organisms that have short life cycles and that are easy to raise in the laboratory are more conducive for developmental phenotypic plasticity. Considerable research has already been carried out on the brine shrimp, Artemia franciscana, regarding its morphology due to changing salinities. There is, however, little research considering subsequent generations and how there morphology might be affected by parental experiences. This study has examined: 1) the morphological effects of different rearing regimes of different salinity levels, and 2) the epigenetic transgenerational transfer of these morphological traits in A. franciscana. Measurements included rate of growth (as measured by instar), body size, body length, and other morphological traits. A gradual increase to more hyperosmotic conditions during development produced brine shrimp that were larger in size and also more developmentally advanced. Salinity stress experienced by adults had increased the growth rate in the F1 offspring of A. franciscana. Collectively, these data indicate that Artemia franciscana is a tractable model for investigating phenotypic plasticity. These findings have added to the ever-growing field of developmental phenotypic plasticity while also providing more information on the natural history and adaptive abilities of A. franciscana.
Date: December 2015
Creator: Jones, Shaun Gray

Investigation of Inhibitory Influences in Neuronal Monolayer Networks Cultured from Mouse Spinal Cord

Description: The effects of the inhibitory neurotransmitters gammaamino butyric acid (GABA) and glycine were characterized on spontaneous activity recorded from mouse spinal cord cultures. The GABA concentration which completely inhibited burst activity was chosen as a quantifiable measure of culture drug response and was used to 1) assess interculture and intraculture variability, 2) determine the influence of culture age and initial activity on GABA responses, and 3) compare the GABA responses between networks obtained from whole spinal cord and ventral half spinal cord. Results showed that 1) no significant variability existed either within or among cultures, 2) the initial culture activity directly affected GABA responses, 3) the culture age had no effect on GABA responses, and 4) there was no significant difference in GABA responses between the two spinal cord tissues.
Date: August 1992
Creator: Jordan, Russell S. (Russell Stall)

Removal of selected water disinfection byproducts, and MTBE in batch and continuous flow systems using alternative sorbents.

Description: A study was conducted to evaluate the sorption characteristics of six disinfection byproducts (DBPs) on four sorbents. To investigate sorption of volatile organic compounds (VOCs), specially designed experimental batch and continuous flow modules were developed. The investigated compounds included: chloroform, 1,2-dichloroethane (DCE), trichloroethylene (TCE), bromodichloromethane (BDCM), methyl tertiary butyl ether (MTBE), bromate and bromide ions. Sorbents used included light weight aggregate (LWA), an inorganic porous material with unique surface characteristics, Amberlite® XAD-16, a weakly basic anion exchange resin, Amberjet®, a strongly basic anion exchange resin, and granular activated carbon (GAC). Batch experiments were conducted on spiked Milli-Q® and lake water matrices. Results indicate considerable sorption of TCE (68.9%), slight sorption of bromate ions (19%) and no appreciable sorption for the other test compounds on LWA. The sorption of TCE increased to 75.3% in experiments utilizing smaller LWA particle size. LWA could be a viable medium for removal of TCE from contaminated surface or groundwater sites. Amberlite® was found unsuitable for use due to its physical characteristics, and its inability to efficiently remove any of the test compounds. Amberjet® showed an excellent ability to remove the inorganic anions (>99%), and BDCM (96.9%) from aqueous solutions but with considerable elevation of pH. Continuous flow experiments evaluated GAC and Amberjet® with spiked Milli-Q® and tap water matrices. The tested organic compounds were sorbed in the order of their hydrophobicity. Slight elevation of pH was observed during continuous flow experiments, making Amberjet® a viable option for removal of BDCM, bromate and bromide ions from water. The continuous flow experiments showed that GAC is an excellent medium for removal of the tested VOCs and bromate ion. Each of the test compounds showed different breakthrough and saturation points. The unique design of the continuous flow apparatus used in the study proved to be highly beneficial to ...
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Date: December 2002
Creator: Kadry, Ahmed Y.

Microsatellite-based genetic profiling for the management of wild and captive flamingo populations.

Description: Flamingo species generate tremendous interest whether they are small captive groups or wild populations numbering in the thousands. Genetic pedigrees are invaluable for maintaining maximum genetic diversity in captive, as well as wild, populations. However, presently there is a general lack of genetic data for flamingo populations. Microsatellites are loci composed of 2-6 base pair tandem repeats, scattered throughout higher eukaryotic genomes, often exhibiting high levels of polymorphism and heterozygosity. These loci are thus important genetic markers for identity, parentage and population studies. Here, six microsatellite loci were isolated from a microsatellite-enriched Caribbean flamingo partial genomic library. Two are compound complex repeats and four are perfect trinucleotide repeats. Each locus was amplified from Caribbean, African greater, Chilean and lesser flamingo genomic DNAs. Heterozygosity frequencies were calculated for Caribbean (range 0.12-0.90) and African greater flamingos (range 0.23-0.94) loci. All six microsatellite loci were found to be in Hardy-Weinberg equilibrium and linkage disequilibrium analyses did not suggest linkage for any pair of two greater flamingo subspecies (African and Caribbean) loci. At least five of the loci also exhibit polymorphism in Chilean and lesser flamingos, but due to small sample numbers, relevant allele/heterozygosity frequency calculations could not be estimated. Nucleotide sequence comparisons of the amplicons derived from the four flamingo groups reveal a high level of sequence conservation at all loci. Although small sample numbers again limit the data for lesser flamingos and to some degree for the Chilean birds, the sequences of the two greater flamingo subspecies were identical and the number of nonconserved nucleotides appears to be higher for lesser/greater comparisons than for Chilean/greater comparisons. This is consistent with Chilean flamingos being a different species within the same genus as the greater flamingos, while lesser flamingos belong to a separate genus. Parentage analyses on suggested African greater flamingo family groups from ...
Date: December 2005
Creator: Kapil, Richa

Influence of stormwater drainage facilities on mosquito communities within the city of Denton, Texas.

Description: Weekly collections were conducted from May to December, 2007 (153 trap nights, total) in Denton, Texas, in and around large storm drains and overpass drainage facilities in residential and non-residential areas, using Centers for Disease Control (CDC) light traps and gravid traps. A total of 1964 mosquitoes were collected, representing 24 species within 6 genera: Aedes, Anopheles, Culiseta, Culex, Psorophora, and Uranotaenia. Culex was the most abundant genus, representing 75% of all mosquitoes collected; Aedes was the second most abundant, representing 12 % of all mosquitoes collected. Cx. quinquefasciatus was the dominant species collected via gravid traps; Cx. (Melanoconion) species were the dominant species collected via CDC light traps. Data of gravid traps and light traps were analyzed separately using nonparametric correlation analysis, comparing environmental data and physical characteristics to total abundance of mosquitoes. There was no significant correlation found when comparing the three dominant species collected in light traps (unidentified Cx. (Melanoconion) sp, Cx. quinquefasciatus, and Ae. vexans) to environmental characteristics and physical characteristics. Analysis of Cx. quinquefasciatus collected in gravid traps indicated no significant correlation between abundance, environmental data, and physical characteristics. Linear regression models were analyzed to determine if either environmental variables or physical characteristics of the drainage system explained the species abundance collected; no individual variable showed an association of significance. Analysis of Cx. quinquefasciatus collected in storm drains via gravid traps determined temperature to be the most important variable in determining population abundance and explained 99% of the population variability.
Date: December 2008
Creator: Kavanaugh, Michael David

An Assessment of Storm Water Toxicity from the Dallas/Fort Worth Metroplex and Denton, Texas

Description: With the advent of national storm water regulations, municipalities with populations greater than 100,000 are required to obtain National Pollutant Discharge Elimination System Permits (NPDES) for storm water discharges. In addition to the sampling required for the permit process, the City of Fort Worth contracted with the University of North Texas' Institute of Applied Sciences to conduct acute toxicity testing using Pimephales prcmelas and Ceriodaphnia dubia on storm water samples received from the Dallas/Fort Worth Metroplex. A Toxicity Identification Evaluation (TIE) was performed on four samples that exhibited acute toxicity to C. dubia. High levels of metals as well as diazinon were some of the probable toxicants found.
Date: August 1995
Creator: Keating, Paul Redmond

Unique applications of cultured neuronal networks in pharmacology, toxicology, and basic neuroscience

Description: This dissertation research explored the capabilities of neuronal networks grown on substrate integrated microelectrode arrays in vitro with emphasis on utilizing such preparations in three specific application domains: pharmacology and drug development, biosensors and neurotoxicology, and the study of burst and synaptic mechanisms. Chapter 1 details the testing of seven novel AChE inhibitors, demonstrating that neuronal networks rapidly detect small molecular differences in closely related compounds, and reveal information about their probable physiological effects that are not attainable through biochemical characterization alone. Chapter 2 shows how neuronal networks may be used to classify and characterize an unknown compound. The compound, trimethylol propane phosphate (TMPP) elicited changes in network activity that resembled those induced by bicuculline, a known epileptogenic. Further work determined that TMPP produces its effects on network activity through a competitive inhibition of the GABAA receptor. This demonstrates that neuronal networks can provide rapid, reliable warning of the presence of toxic substances, and from the manner in which the spontaneous activity changes provide information on the class of compound present and its potential physiological effects. Additional simple pharmacological tests can provide valuable information on primary mechanisms involved in the altered neuronal network responses. Chapter 3 explores the effects produced by a radical simplification of synaptic driving forces. With all synaptic interactions pharmacologically limited to those mediated through the NMDA synapse, spinal cord networks exhibited an extremely regular burst oscillation characterized by a period of 2.9 ± 0.3 s, with mean coefficients of variation of 3.7, 4.7, and 4.9 % for burst rate, burst duration, and inter-burst interval, respectively (16 separate cultures). The reliability of expression of this oscillation suggests that it may represent a fundamental mechanism of importance during periods of NMDA receptor dominated activity, such as embryonic and early postnatal development. NMDA synapse mediated activity produces a precise ...
Date: May 2001
Creator: Keefer, Edward W.