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Some Acute Effects of X-Irradiation (LD100) on Plasma and Adrenal Tissue Histamine in Rats
The effects of a lethal dose (1380 r) of X-irradiation on plasma and adrenal tissue histamine levels of rats were studied. The plasma histamine response was triphasic (increase at 1-3 hours, decrease at 5 and 9 hours and return to control at 24 hours post-irradiation). The adrenal tissue histamine response was found to be biphasic (decrease at 1 to 9 hours and a return to control level at 24 hours post-irradiation).
Effects of Carbaryl (1-Naphthyl-n-methylcarbamate) on Trichocorixa Reticulata (Hemiptera: Corixidae) and Glyptotendipes Barbipes (Diptera: Chironomidae)
My study of the effects of carbaryl in aquatic systems under controlled laboratory conditions emphasized four major objectives: (1) to determine the acute toxicity of carbaryl to the herbivorous adult and immature Trichocorixa reticulata (Guerin)(Hemiptera: Corixidae), and to the omnivorous larvae of Glyptotendipes barbipes (Staeger) (Diptera: Chironomidae) under static bioassay; (2) to adapt a quantitative method of analysis for carbaryl in water and whole insect tissue extract; (3) to measure the accumulation of the insecticide by G. barbipes under static exposure; and (4) to quantify the uptake and loss of carbaryl by G. barbipes under daily-renewed sublethal dosages.
Effects of a Methylcholanthrene-Induced Lymphosarcoma on the Blood of DBA/1J Mice
This investigation was concerned with characterizing a tumor line induced and maintained in this laboratory. Various chemical assays, cell counts, and electron microscopy were the methods employed to characterize the blood of mice bearing the tumor at days 3, 6, 9, and 12 after injection of the 1.2 x 10^8 tumor cells.
Proteomic Responses in the Gill of Zebrafish Following Exposure to Ibuprofen and Naproxen
Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most abundant environmental pharmaceutical contaminants. In this study, a proteomic analysis was conducted to identify proteins differentially expressed in gill tissue of zebrafish (Danio rerio) after a 14-day exposure to the NSAIDs ibuprofen or naproxen. A total of 104 proteins with altered expression as indicated by 2-dimensional electrophoresis were analyzed by liquid chromatography with ion trap mass spectrometry (MS/MS). A total of 14 proteins fulfilled our requirements for identification which included consistency among replicate gels as well as successful MS/MS ion searches with the MASCOT database. The most prominent feature of the differential protein expression observed after NSAID exposure was an up-regulation of proteins belonging to the globin family which are involved in the transport of oxygen from gills and availability of heme molecules required for synthesis of cyclooxygenase. Differential expression was observed at exposure concentrations as low as 1-10 µg/L indicating that altered gene expression may occur in fish subjected to environmentally realistic levels of NSAID exposure.
Hypoxia and the Development of Endothermic Capacity in Chickens (Gallus Gallus)
Adult chickens employ endothermy – internal generation of heat that maintains a constant body temperature (Tb). Prior to hatching, chicken embryos are ectothermic - controlling Tb by external heat sources. Upon hatching, the hatchling transitions from an ectotherm to an endotherm that has been shown to be delayed by hypoxia. In this study, whole animal oxygen consumption () and liver, heart, and skeletal muscle citrate synthase activity (CSA) and were measured during this transition to endothermy in chickens incubated in normoxia and hypoxia (15% O2). The only significant differences in occurred in 48 hour old hatchlings where was lower in normoxic hatchlings. There were no differences in CS activity between age and incubation oxygen levels. Additionally, preliminary 2-D protein gels of embryo and hatchling liver show changes in the proteome upon hatching. Results suggest that hypoxia had no significant effect on CSA and a minimal effect on .
Comparison of Aspartate Transcarbamoylase Activity Between Pseudomonas Aeruginosa Which Has One Chromosome and Burkholderia Cepacia Which Has Three Chromosomes
The pyrimidine biosynthetic pathway is essential and similar in all bacteria. The pathway from Pseudomonas is regulated by nucleotides which bind to the upstream region of the pyrBC’ gene complex. Work in our lab mapped the genes and showed that the pyrB and pyrC’ were part of an overlap complex. The Pseudomonas aeruginosa has one circular chromosome. A former Pseudomonas now called Burkholderia cepacia is similar to P. aeruginosa except that it contains three circular chromosomes (CI, CII, CIII) and one large plasmid. The primary chromosome named CI contains the pyrBC’. To our knowledge there has been no report of the activity of ATCase in Pseudomonas and contrasted with that of Burkholderia. Here, we compare the activity of ATCase in P. aeruginosa and B .cepacia. Cells of both organisms were grown in Pseudomonas minimal medium and in Enriched medium. The ATCase was extracted and partially purified from each sample. It is hypothesized that the B. cepacia has greater activity for ATCase than do the Pseudomonas.
Optimizing Scientific and Social Attributes of Pharmaceutical Take Back Programs to Improve Public and Environmental Health
Research continues to show that pharmaceutical environmental contamination has caused adverse environmental effects, with one of the most studied effects being feminization of fish exposed to pharmaceutical endocrine disruptors. Additionally, there are also public health risks associated with pharmaceuticals because in-home reserves of medications provide opportunities for accidental poisoning and intentional medication abuse. Pharmaceutical take back programs have been seen as a remedy to these concerns; however a thorough review of peer-reviewed literature and publicly available information on these programs indicates limited research has been conducted to validate these programs as a purported solution. Furthermore, there are significant data gaps on key factors relating to take back program participants. The purpose of this dissertation was therefore to address these gaps in knowledge and ultimately determine if take back programs could actually improve public and environmental health. This was accomplished by conducting social and scientific research on a take back program called Denton Drug Disposal Day (D4). Socioeconomic, demographic, and geographic characteristics of D4 participants were investigated using surveys and geographic analysis. Impacts on public health were determined by comparing medications collected at D4 events with medications reported to the North Texas Poison Center as causing adverse drug exposures in Denton County. Impacts to environmental health were determined by monitoring hydrocodone concentrations in wastewater effluent released from Denton’s wastewater treatment plant before and after D4 events. Data collected and analyzed from the D4 events and the wastewater monitoring suggests D4 events were successful in contributing to improvements in public and environmental health; however there was insufficient evidence to prove that D4 events were exclusively responsible for these improvements. An additional interesting finding was that willingness to travel to participate in D4 events was limited to a five to six mile threshold. This geographic information, combined with other findings related to socioeconomic, …
Modeling the Relationship Between Golden Algae Blooms in Lake Texoma, Usa, Versus Nearby Land Use and Other Physical Variables
Pyrmnesium parvum, commonly known as golden algae, is an algal species that under certain circumstances releases toxins which can lead to fish kills and the death of other economically and ecologically important organisms. One of the major objectives of the study was to investigate whether a relationship exists between land use and Prymnesium parvum abundance in littoral sites of Lake Texoma, USA. Another objective was to investigate whether a relationship exists between other physical variables and counts of P. parvum. Lastly, developing a valid model that predicts P. parvum abundance was an objective of the study. Through stepwise regression, a small but highly significant amount of the variation in P. parvum counts was found to be explained by wetlands, soil erodibility and lake elevation. The developed model provides insight for potential golden algae management plans, such as maintaining wetlands and teaching land owners the relationship between soil erosivity and golden algae blooms.
A Socio-ecological Assessment of Watershed Ecosystem Services in Southern Patagonia
This thesis utilizes a theoretical framework which links biophysical and social domains of ecosystems via ecosystem services (ES), in order to conduct a socio-ecological assessment of urban watersheds in three communities in Chilean and Argentine regions of southern Patagonia. Results from this study show that expanding urban areas may be undermining the ability of local watersheds to provide for high quality ES posing potential risks to community wellbeing. Secondly, researchers and decision makers influencing regional natural resource management share similar values to general community members but do not capture the diversity of values that exist within the broader community, and dialogue between these groups on management issues is poor. A community-based management structure is recommended for the creation of adaptive and locally relevant management strategies.
The Larval Lipids of the Chironomid Midge Glyptotendipes Barbipes (Staeger)
This problem was concerned with determining the total lipid content and individual lipid composition of the larvae of a local chironomid, Glyptotendipes barbipes (Staeger).
Some Effects of Electrostatic Fields on Brain Activity in Rats
This study concerned the effects of short-term exposures to continuous (10 kv/meter) and pulsed 20 volts at 640 cps/100 msecs) electrostatic fields on the EEG recorded from external electrodes and hypothalamic activity recorded from implanted electrodes in rats. Each experiment lasted at least 90 minutes. The total energies of the waveforms recorded were integrated and printed out for plotting and analysis. Besides the brain activity, the ECG, respiration, and temperature of the animals were also monitored before, during,and after exposure to the electrostatic fields.
Influence of Acclimation and Acclimatization to Seasonal Temperatures on Metabolism and Energetics in the Rusty Lizard Sceloporus Olivaceus
Rates and energy equivalents of consumption (C), egestion+ excretion (FU) , assimilation (A), respiration (R) and production (P) were measured in two groups of Sceloporus olivaceus: 1) a laboratory group acclimated at four seasonally encountered temperatures (15, 20, 25 and 30°C) ; and 2) four acclimatization groups collected at different seasons when ambient temperatures corresponded to 15, 20, 25 and 30°C.
Effects of 2-Chloroethylphosphonic Acid (Ethephen) on Scenedesmus Quadricauda
The effects of various concentrations of 2-chloroethylphosphcnic acid (Ethephon), an ethylene-releasing compound, on the total protein, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA) levels in Scenedesmus quadricauda IU 614 were investigated.
Effect of Indole-3-Acetic Acid on the Nucleic Acids of Synchronous Cultures of Chlorella Pyrenoidosa
It was the purpose of this study to investigate the effect of various concentrations of IAA on the nucleic acids of Chlorella pyrenoidosa TX 7-11-05. The time during the life cycle when the greatest effect occurred was investigated by the use of synchronous cultures.
A Carcinogenic Agent Elaborated by Liver Cells from Lymphosarcoma-Bearing Mice
Liver cells from lymphosarcoma-bearing DBA/1J mice were shown, by parabiotic culture with normal liver cells from isologous mice, to elaborate an agent which could pass a 25 mu filter and transform the normal cells to a malignant state.
Individual, Social, and Seasonal Behavior of the Thirteen-Lined Ground Squirrel (Spermophilus tridecemlineatus)
The purpose of this study is to provide a qualitative, detailed description of individual and social behavior in a free-living population of thirteen-lined ground squirrels. Behavioral differences in relation to various periods of the annual cycle are also evaluated.
Obligately Thermophilic Nitrogen-Fixation in Some Soil Bacteria
In the work presented here, it is claimed that bacteria have been isolated which are capable of growth at high temperatures utilizing molecular nitrogen as their sole nitrogen source. Soil bacteria were isolated which grew at 55 C in nitrogen-free media. They were found to be obligatory thermophiles in nitrogen-free media and facultative thermophiles in media containing organically bound nitrogen.
Experimental Trichinosis in Birds
This work concerns itself with essentially four experiments: (1) the cecum-injective-infection experiment; (2) the anus-injective-infection experiment; (3) the mouth ingestive-infection with larvae, and (4) the mouth ingestive-infection with the flesh of infected rats.
Mixed Culture of Chlorella Pyrenoidosa TX71105 and a Variant Strain of Bacillus Megaterium
Very little work has been done on bacteria capable of significantly inhibiting algal growth. This thesis reports the research on mixed cultures of a high-temperature strain of algae, Chlorella pyrenoidosa TX71105, and an organism isolated from the air and tentatively identified as a variant strain of Bacillus megaterium.
Studies on Plant-aphid Interactions: a Novel Role for Trehalose Metabolism in Arabidopsis Defense Against Green Peach Aphid
Myzus persicae (Sülzer), commonly known as the green peach aphid (GPA), is a polyphagous insect that can infest over 100 families of economically important plants and is major pest for vegetable crops. This study utilizes the Arabidopsis-GPA model system with the aim to elucidate the role of the plant disaccharide trehalose in providing defense against GPA. This study demonstrates a novel role for TPS11 in providing defense against GPA. TPS11 expression was found to be transiently induced in Arabidopsis plants in response to GPA infestation and the TPS11 gene was required for curtailing GPA infestation. TPS11, which encodes for trehalose phosphate synthase and phosphatase activities, contributes to the transient increase in trehalose in the GPA infested tissues. This work suggests that TPS11-dependent trehalose has a signaling function in plant defense against GPA. in addition, trehalose also has a more direct role in curtailing GPA infestation on Arabidopsis. This work also shows that TPS11 is able to modulate both carbohydrate metabolism and plant defenses in response to GPA infestation. the expression of PAD4, an Arabidopsis gene required for phloem-based defenses against GPA, was found to be delayed in GPA infested tps11 mutant plants along with increased sucrose levels and lower starch levels as compared to the GPA infested wild type plants. This work provides clear evidence that starch metabolism in Arabidopsis is altered in response to GPA feeding and that TPS11-modulated increase in starch contributes to the curtailment of GPA infestation in Arabidopsis.
A Comparison of Mercury Localization, Speciation, and Histology in Multiple Fish Species From Caddo Lake, a Fresh Water Wetland
This work explores the metabolism of mercury in liver and spleen tissue of fish from a methylmercury contaminated wetland. Wild-caught bass, catfish, bowfin and gar were collected. Macrophage centers, which are both reactive and primary germinal centers in various fish tissues, were hypothesized to be the cause of demethylation of methylmercury in fish tissue. Macrophage centers are differentially expressed in fish tissue based on phylogenetic lineage, and are found primarily in the livers of preteleostean fish and in the spleen of teleostean fish. Histology of liver and spleen was examined in both control and wild-caught fish for pathology, size and number of macrophage centers, and for localization of mercury. Total mercury was estimated in the muscle tissue of all fish by direct mercury analysis. Selenium and mercury concentrations were examined in the livers of wild-caught fish by liquid introduction inductively coupled plasma mass spectrometry (ICP-MS). Total mercury was localized in histologic sections by laser ablation ICP-MS (LA-ICP-MS). Mercury speciation was determined for inorganic and methylmercury in liver and spleen of fish by bas chromatography-cold vapor atomic fluorescence spectroscopy (GC-CVAFS). Macrophage center tissue distribution was found to be consistent with the literature, with a predominance of centers in preteleostean liver and in spleens of teleostean fish. Little evidence histopathology was found in the livers or spleens of fish examined, but differences in morphology of macrophage centers and liver tissue across species are noted. the sole sign of liver pathology noted was increased hepatic hemosiderosis in fish with high proportions of liver inorganic mercury. Inorganic mercury was found to predominate in the livers of all fish but bass. Organic mercury was found to predominate in the spleens of all fish. Mercury was found to accumulate in macrophage centers, but concentrations of mercury in this compartment were found to vary less in relation …
Alterations in Fatty Acid Amide Hydrolase (Faah) Transcript Levels and Activity Lead to Changes in the Abiotic Stress Susceptibility of Arabidopsis Thaliana
N-Acylethanolamines (NAEs) are a class of bioactive lipids, and FAAH is one of the enzymes responsible for degrading NAEs in both plants and animals. in plants, FAAH appears to be closely associated with ABA, a phytohormone which has long been associated with plant stress responses, since the overexpression of FAAH in Arabidopsis results in ABA hypersensitivity. Therefore, it is reasonable to speculate that alterations in FAAH transcript levels will result in altered stress responses in plants. to investigate this hypothesis experiments were carried out in which wild type (WT), FAAH-overexpressing (OE), and T-DNA insertional FAAH knockouts of Arabidopsis (faah) were grown in MS media under stress conditions. the stress conditions tested included chilling stress, heavy metal stress induced by cadmium or copper, nutrient limitations induced by low phosphorus or low nitrogen, salt stress induced with NaCl, and osmotic stress induced with mannitol. the OE plants were consistently hypersensitive to all stress conditions in relation to wild type plants. Inactive FAAH overexpressors did not have the hypersensitivity to the salt and osmotic stress of the active OE plants and were instead tolerant to these stresses. FAAH2 (faah2) knockouts and FAAH 1 and 2 double knockouts (faah 1+2) were based on some root development parameters somewhat more tolerant than WT plants, but more sensitive in terms of shoot growth. Collectively the data suggests that FAAH activity may interact with stress-responsive pathways in plants, perhaps including pathways involving ABA.
Ecological Significance and Underlying Mechanisms of Body Size Differentiation in White-tailed Deer
Body size varies according to nutritional availability, which is of ecological and evolutionary relevance. The purpose of this study is to test the hypothesis that differences in adult body size are realized by increasing juvenile growth rate for white-tailed deer (Odocoileus virginianus). Harvest records are used to construct growth rate estimates by empirical nonlinear curve fitting. Results are compared to those of previous models that include additional parameters. The rate of growth increases during the study period. Models that estimate multiple parameters may not work with harvest data in which estimates of these parameters are prone to error, which renders estimates from complex models too variable to detect inter-annual changes in growth rate that this simpler model captures
Effects of Layer Double Hydroxide Nanoclays on the Toxicity of Copper to Daphnia Magna
Nanoparticles may affect secondary pollutants such as copper. Layer Double Hydroxides (LDH) are synthetically produced nanoparticles that adsorb copper via cation exchange. Pretreatment of copper test solutions with LDH nanoparticles followed by filtration removal of LDH nanoparticles demonstrated the smallest LDH aggregates removed the most copper toxicity. This was due to increased surface area for cation exchange relative to larger particle aggregates. Co-exposure tests of copper chloride and clay were run to determine if smaller clay particles increased copper uptake by D. magna. Coexposure treatments had lower LC50 values compared to the filtration tests, likely as a result of additive toxicity. LDH nanoclays do reduce copper toxicity in Daphnia magna and may serve as a remediation tool.
Ecology and Recolonization of Benthic Macroinvertebrates in a Groundwater-dependent Stream in North Central Texas During a Supra-seasonal Drought
Extreme climatic events such as droughts are known to eliminate aquatic biota and alter community structure and function. Perennial headwater springs provide important drought refugia to benthic macroinvertebrates and an important source of colonists via drift or aerial adults to intermittent streams post-drought. During a supra-seasonal drought in North-central Texas summer and fall 2006, benthic macroinvertebrates from persistent groundwater-dependent macrohabitats of varying hydrological connectivity and riparian shading were studied: perennial riffles, connected pools, shaded disconnected pools, and full sun disconnected pools. Riffles were a distinct habitat with significantly higher taxa richness, proportion of lotic taxa, diversity and evenness than other macrohabitats. Macrohabitats were found to be important refugia for 106 benthic macroinvertebrates and 4 microcrustacean taxa. Throughout the extreme drought, perennially flowing habitats were refugia to 19 taxa (17.9% total taxa) not collected in disconnected pools. Shaded disconnected pools contained lotic taxa not previously known to be able to complete their lifecycles in lentic habitats, emphasizing the importance of groundwater effluent and shading. With the resumption of flow at a downstream intermittent site of Ash Creek in mid-October 2006, an annual recolonization study was conducted comparing the perennial headwaters’ benthic macroinvertebrate taxa richness, densities and community ecology with the downstream intermittent site. The headwaters supported higher mean taxa richness than the intermittent site over the duration of the study (ANOVA P < 0.001). However, the unexpected result of overall decreasing taxa richness at the perennial headwater site from August 2006 to April 2008 appears to reflect lag effects of the supra-seasonal drought combined with effects of multiple spates of 2007, which are factors confounding the point of recovery for taxa richness. Recovery of taxa richness at the intermittent site took 9 months compared to 1 to 2 months reported in other arid and semi-arid streams in the United States recovering …
Investigating Realistic Scenarios of Biodiversity Loss on Ecosystem Functioning: Extirpation of Rare Species and Food Web Collapse in Tropical Floodplain Lagoons
This thesis investigates the influence of nonrandom species loss on the structure and functioning of trophic floodplain lagoons. Two experiments were conducted based on different realistic scenarios of biodiversity loss using multitrophic fish assemblages derived from long-term survey data. Loss of fish diversity influenced overall ecosystem multifunctionality of these lagoons through complex multitrophic interactions throughout the aquatic food web. These results indicate that biodiversity loss from diverse multitrophic ecosystems can influence ecosystem structure and function and likely deviate from simplified food chain dynamics or patterns that emerged from single trophic level studies.
Identification of Three Symbiosome Targeting Domains in the MtENOD8 Protein and Cell-to-cell MtENOD8 mRNA Movement in Nodules
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 as the symbiosome where nitrogen fixation occurs. the symbiosome is enriched in plant proteins, however, little is known about the mechanisms that direct plant proteins to the symbiosome. Using the M. truncatula ENOD8 (MtENOD8) protein as a model to explore symbiosome protein targeting, 3-cis domains were identified within MtENOD8 capable of directing green fluorescent protein (GFP) to the symbiosome, including its N-terminal signal peptide (SP). the SP delivered GFP to the vacuole in the absence of nodules suggesting that symbiosome proteins share a common targeting pathway with vacuolar proteins. a time course analysis during nodulation indicated that there is a nodule specific redirection of MtENOD8-SP from the vacuole to the symbiosome in a MtNIP/LATD dependent manner. GFP expression by the MtENOD8 promoter revealed spatial discrepancy between promoter activity and protein localization. in situ localization of MtENOD8 mRNA showed localization to infected cells, where the protein is found, suggesting mRNA cell-to-cell movement. Expression of MtENOD8 in Arabidopsis showed that the SP did not direct GFP to the vacuole indicating that vacuolar targeting of MtENOD8’s SP may be legume specific. Taken together, the research presented here indicates that the MtENOD8 symbiosome protein has evolved redundant domains for targeting, which has part of a common pathway with vacuolar proteins. Observed spatial discrepancy between the MtENOD8 promoter and protein shows additional mechanisms of gene regulation through cell-to-cell mRNA …
Integrating Selective Herbicide and Native Plant Restoration to Control Alternanthera philoxeroides (Alligator Weed)
Exotic invasive aquatic weeds such as alligator weed (Alternanthera philoxeroides) threaten native ecosystems by interfering with native plant communities, disrupting hydrology, and diminishing water quality. Development of new tools to combat invaders is important for the well being of these sensitive areas. Integrated pest management offers managers an approach that combines multiple control methods for better control than any one method used exclusively. In a greenhouse and field study, we tested the effects of selective herbicide application frequency, native competitor plant introduction, and their integration on alligator weed. In the greenhouse study, alligator weed shoot, root, and total biomass were reduced with one herbicide application, and further reduced with two. Alligator weed cumulative stem length and shoot/root ratio was only reduced after two applications. In the greenhouse, introduction of competitors did not affect alligator weed biomass, but did affect shoot/root ratio. The interaction of competitor introduction and herbicide did not significantly influence alligator weed growth in the greenhouse study. In the field, alligator weed cover was reduced after one herbicide application, but not significantly more after a second. Introduction of competitor species had no effect on alligator weed cover, nor did the interaction of competitor species and herbicide application. This study demonstrates that triclopyr amine herbicide can reduce alligator weed biomass and cover, and that two applications are more effective than one. To integrate selective herbicides and native plant introduction successfully for alligator weed control, more research is needed on the influence competition can potentially have on alligator weed growth, and the timing of herbicide application and subsequent introduction of plants.
Life History And Secondary Production Of Cheumatopsyche Lasia Ross (Trichoptera: Hydropsychidae) With Respect To A Wastewater Treatment Facility In A North Texas Urban Stream
This study represents the first shift in multivoltine life history of Cheumatopsyche species from a wastewater treatment plant (WWTP) in North America. Populations of C. lasia were examined upstream and downstream of the Denton’s Pecan Creek WWTP August 2009 through November 2010. C. lasia is multivoltine in Pecan Creek with three cohorts observed upstream of the WWTP and four possible cohorts downstream. A fourth generation was possible downstream as thermal inputs from WWTP effluent resulted in elevated water temperatures that allowed larval development to progress through the winter producing a cohort ready to emerge in spring. Production of C. lasia was 5 times greater downstream of the WWTP with secondary production estimates of 1.3 g m-2 yr-1 and 4.88- 6.51 g m-2 yr-1, respectively. Differences in abundance were due to increased habitat availability downstream of the WWTP in addition to continuous stream flow from inputs of wastewater effluent. Results also suggest that C. lasia is important for energy transfer in semiarid urban prairie streams and may serve as a potential conduit for the transfer of energy along with emergent contaminants to terrestrial ecosystems. These finding highlight the need for more quantitative accounts of population dynamics (voltinism, development rates, secondary production, and P/B) of aquatic insect species to fully understand the ecology and energy dynamics of urban systems.
A Characterization Of Jackson Blue Spring, Jackson County, Florida
Jackson Blue is a first magnitude spring in the karst terrane of northeast Florida. Previous studies have identified inorganic fertilizer as the source of high nitrate levels in the spring. Agricultural land use and karst vulnerability make Jackson Blue a good model for conservation concerns. This work offers an aggregation of studies relating to the springshed, providing a valuable tool for planning and conservation efforts in the region. An analysis of nitrate levels and other water quality parameters within the springshed did not reveal significantly different values between agricultural and forested land use areas. Confounding factors include: high transmissivity in the aquifer, interspersed land use parcels, and fertilizer application in forested areas due to commercial pine stand activity.
Ultraviolet Radiation Tolerance in High Elevation Copepods from the Rocky Mountains of Colorado, USA
Copepods in high elevation lakes and ponds in Colorado are exposed to significant levels of ultraviolet radiation (UV), necessitating development of UV avoidance behavior and photoprotective physiological adaptations. The copepods are brightly pigmented due to accumulation of astaxanthin, a carotenoid which has photoprotective and antioxidant properties. Astaxanthin interacts with a crustacyanin-like protein, shifting its absorbance from 473 nm (hydrophobic free form, appears red) to 632 nm (protein-bound complex, appears blue). In six sites in Colorado, habitat-specific coloration patterns related to carotenoprotein complex have been observed. The objective of this study was to determine whether pigment accumulation or carotenoprotein expression has a greater effect on resistance to UV exposure. For each site, copepod tolerance to UV was assessed by survivorship during UV exposure trials. Average UV exposure was determined for each habitat. Astaxanthin profiles were generated for copepods in each site. Ability to withstand UV exposure during exposure trials was significantly different between color morphs (p < 0.0001). Red copepods were found to tolerate 2-fold greater levels of UVB than blue or mixed copepods. Additionally, red copepods have much higher levels of total astaxanthin than blue or mixed copepods (p < 0.0001) and receive a higher daily UV dose (p < 0.0003). Diaptomid carotenoprotein sequence is not homologous with that of other crustaceans in which crustacyanin has been characterized which prevented quantification of carotenoprotein transcript expression. Overall, diaptomid color morph may be an important indicator of UV conditions in high elevation lentic ecosystems.
Measuring Atmospheric Ozone and Nitrogen Dioxide Concentration by Differential Optical Absorption Spectroscopy
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.
Effect of Rancher’s Management Philosophy, Grazing Practices, and Personal Characteristics on Sustainability Indices for North Central Texas Rangeland
To assess sustainability of privately owned rangeland, a questionnaire was used to gathered data from ranches in Cooke, Montague, Clay, Wise, Parker, and Jack counties in North Central Texas. Information evaluated included: management philosophy, economics, grazing practices, environmental condition, quality of life, and demographics. Sustainability indices were created based on economic and land health indicator variables meeting a minimum Cronbach‘s alpha coefficient (α = 0.7). Hierarchical regression analysis was used to create models explaining variance in respondents’ indices scores. Five predictors explained 36% of the variance in rangeland economic sustainability index when respondents: 1) recognized management inaction has opportunity costs affecting economic viability; 2) considered forbs a valuable source of forage for wildlife or livestock; 3) believed governmental assistance with brush control was beneficial; 4) were not absentee landowners and did not live in an urban area in Texas, and; 5) valued profit, productivity, tax issues, family issues, neighbor issues or weather issues above that of land health. Additionally, a model identified 5 predictors which explained 30% of the variance for respondents with index scores aligning with greater land health sustainability. Predictors indicated: 1) fencing cost was not an obstacle for increasing livestock distribution; 2) land rest was a component of grazing plans; 3) the Natural Resource Conservation Service was used for management information; 4) fewer acres were covered by dense brush or woodlands, and; 5) management decisions were not influenced by friends. Finally, attempts to create an index and regression analysis explaining social sustainability was abandoned, due to the likely-hood of type one errors. These findings provide a new line of evidence in assessing rangeland sustainability, supporting scientific literature concerning rangeland sustainability based on ranch level indicators. Compared to measuring parameters on small plots, the use of indices allows for studying replicated whole- ranch units using rancher insight. Use …
Genetic and Environmental Factors that Mediate Survival of Prolonged Oxygen Deprivation in the Nematode Caenorhabditis Elegans
Ischemic events of even a very short duration are not tolerated Ill in humans. The human cost of ischemia, when looked at as combined cardiovascular disease, dwarfs all other causes of death in the United States. Annually, CVD kills as many people in the US as does cancer, chronic lower respiratory disease, accidents, and diabetes mellitus combined. In 2005 (the latest year for which final statistics are available), CVD was responsible for 864,480 deaths or 35.3 percent of total deaths for the year. In my study, I have used the nematode Caenorhabditis elegans to determine genetic and environmental modulators of oxygen deprivation a key component of ischemia. I have found that animals with mutations in insulin like signaling pathways, neuronal function, electron transport chain components, germline function, and animals that are preconditioned by being raised on a diet of E. coli HT115 bacteria at 25°C have an enhanced ability to survive long-term (>72 hours) anoxia (<.005 kPa O2) at 20°C. The enhanced anoxia survival phenotype partially correlates with increased levels of carbohydrate stores in the nematodes. Suppression of this enhanced anoxia survival phenotype is possible by altering expression of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, the FOXO transcription factor DAF-16, and 5’-AMP kinase.
Benthic Macroinvertebrates of Temperate, Sub-Antarctic Streams: The Effects of Altitudinal Zoning and Temperature on the Phenology of Aquatic Insects Associated to the Robalo River, Navarino Island (55°S), Chile
The Cape Horn Biosphere Reserve, within the remote Sub-Antarctic ecoregion is a reservoir of expressions of biological and cultural diversity. Although it is considered one of 24 wilderness areas remaining in the world, it is not free from local and global threats, such as invasive species, and climate change. Field biologists and philosophers associated to the Sub-Antarctic Biocultural Conservation Program and the Omora Ethnobotanical Park, have worked to describe the region’s biocultural diversity, linking ecological and philosophical research into education, ecotourism, and conservation, through a methodology called field environmental philosophy (FEP), which integrates ecological sciences and environmental ethics through a 4-step cycle consisting of: 1) interdisciplinary research; 2) composition of metaphors; 3) design of field activities with an ecological and ethical orientation; and 4) implementation of in situ conservation areas. In this context, the purposes of this dissertation were to: 1) provide a comprehensive review of publications regarding the conservation status of aquatic and terrestrial insects at a global scale and with an emphasis in southern South America; 2) study the distribution of benthic macroinvertebrates through the sharp altitudinal gradient of the Róbalo River watershed; 3) describe the life histories of Gigantodax sp (Simuliidae: Diptera) and Meridialaris chiloeense (Leptophlebiidae: Ephemeroptera) in the Róbalo River and to assess the potential effects of climate change on their phenology; and 4) to apply FEP methodology in order to better understand and communicate the intrinsic and instrumental values of freshwater invertebrates in the Cape Horn Biosphere Reserve.
The Relationship of Force on Myosin Subfragment 2 Region to the Coiled-Coiled Region of the Myosin Dimer
The stability of myosin subfragment 2 was analyzed using gravitational force spectroscopy. The region was found to destabilize under physiological force loads, indicating the possibility that subfragment 2 may uncoil to facilitate actin binding during muscle contraction. As a control, synthetic cofilaments were produced to discover if the observations in the single molecule assay were due to the lack of the stability provided by the thick filament. Statistically, there was no difference between the single molecule assay data and the synthetic cofilament assay data. Thus, the instability of the region is due to intrinsic properties within subfragment 2.
Soil and Forest Variation by Topography and Succession Stages in the Greenbelt Corridor, Floodplain of the Elm Fork of the Trinity River, North Texas.
The Greenbelt Corridor (GBC), located in a floodplain of the Elm Fork of the Trinity River, contains patches of bottomland forest and serves as part of Lake Lewisville’s flood control backwaters. This study examines forest structure and composition in relation to topographic position and forest stage in the GBC. Thirty two plots were surveyed within various stage classes, topographic positions, and USDA soil types. Trees were identified and measured for height and DBH. Density, basal area, and importance value for each of species was calculated. Soil and vegetation were analyzed using ANOVA, Principal Component Analysis, Canonical Correlation, Canonical Correspondence Analysis and Cluster Analysis. Tests confirmed that calcium carbonate and pH show significant differences with topographic positions but not with forest stage. Potassium shows no significant difference with soil texture class. Sand shows a strong negative correlation with moisture, organic matter, organic carbon and negative correlation with calcium carbonate and potassium. Silt shows positive correlation with moisture, organic matter, organic carbon, and calcium carbonate. Clay shows strong positive correlation with moisture, organic matter and organic carbon but negative correlations with pH. Swamp privet is dominant tree types in wetland forest. Sugarberry cedar elm, green ash and American elm are widely distributed species in the study area covering low ridges, flats, and slough. In total, density is significantly different in wetland low forest and late successional stage and basal area is significantly different in early successional stage and late successional stage. Other results show that clay is negatively correlated with American elm but positively correlated with cedar elm. Organic matter and moisture shows a strong positive correlation with cedar elm. Calcium carbonate is associated with green ash and swamp privet, sand is associated with sugarberry and red mulberry, silt and pH with cedar elm and bur oak.
Effects of CFT Legumine™ Rotenone on Macroinvertebrates in Four Drainages of Montana and New Mexico
Rotenone is considered essential in the restoration of native fish populations; however, the technique is contentious and criticized, specifically concerning impacts to invertebrates. Knowledge of effects to non-target organisms is important for the management and conservation of fish populations. This thesis has two general objectives: (1) demonstrate the influence CFT Legumine™ rotenone has on benthic macroinvertebrates for restoration projects in Montana and New Mexico and (2) evaluate the immediate response by means of invertebrate drift. Chapters 2 and 4 incorporate results from four different restoration projects that examine benthic macroinvertebrate response. Results indicate treatment effects are minimal for Specimen and Cherry Creek projects in Montana. New Mexico projects, Comanche and Costilla Creek suggest a greater influence. Potassium permanganate used to neutralize rotenone, influenced communities in three of the four projects. Regardless, invertebrates in all four projects recovered one-year after treatment. Chapter 3 examines macroinvertebrate drift during rotenone treatment. Results suggest a delayed response compared to previous literature. Rotenone appears to have the greatest immediate influence on the early life stages of Ephemeroptera and Plecoptera. To reduce impacts of rotenone to invertebrates, managers should apply CFT Legumine and use the minimal dosage and duration to complete the projects goal of removing non-indigenous fish species.
Tests of a New Model of Paclitaxel-Induced Neuropathy and the Effects of Paclitaxel on the Dorsal Root Ganglia
This study examined a new model of paclitaxel-induced neuropathic pain and the effects of systemic paclitaxel on the gap junction protein subunit Cx43 and potassium inwardly-rectifying channel Kir4.1 within the dorsal root ganglia. In the new neuropathic pain model, subplantar injections of paclitaxel resulted in decreased conduction velocities of A-beta fiber compound action potentials in the sciatic (5.9%) and tibial nerves (6.8%) as well as in M (10.6%) and H (10.2%) waves. By using repeated recordings it was found that following paclitaxel injection, conduction velocities in the contralateral plantar nerve increased (9.2%). Systemic injections of paclitaxel resulted in reduced Kir4.1 immunolabeling in the dorsal root ganglia compared to vehicle injections. This reduction was observed in total labeling (32.4%) as well as in areas of intense labeling (28.7%). Reductions in overall Cx43 immunolabeling (25%) and area (25%) following systemic paclitaxel injections were not statistically significant. The results of these studies suggest that subplantar injections of paclitaxel can result in reduced peripheral nerve conduction velocities. The results also show that a unilateral neuropathy can result in contralateral changes in conduction velocities. The effects of paclitaxel on reducing Kir4.1 levels suggest that neuropathic pain caused by paclitaxel may share mechanisms in common with other types of neuropathies which show similar changes in Kir4.1 levels.
Genetic Analysis of Development and Behavior in Hypoxia and Cellular Characterization of Anoxia Induced Meiotic Prophase Arrest in Caenorhabditis Elegans
It was hypothesized that chronic hypoxia will affect various biological processes including developmental trajectory and behavior. To test this hypothesis, embryos were raised to adulthood in severe hypoxic environments (0.5% O2 or 1% O2, 22°C) and analyzed for survival rate, developmental progression, and altered behaviors. Wildtype hermaphrodites survive chronic hypoxia yet developmental trajectory is slowed. The hermaphrodites raised in chronic hypoxia had different phenotypes in comparison to the normoxic controls. First, hermaphrodites exposed to chronic hypoxia produced a significantly lower number of embryos and had a slight increase in male progeny. This suggests that chronic hypoxia exposure during development affects the germline. Second, animals raised in chronic hypoxia from embryos to young adults have a slight increase in lifespan when re-exposed to a normoxic environment, indicating that chronic hypoxia does not negatively decrease lifespan. Finally, hermaphrodites that were raised in hypoxia will lay the majority of their eggs on the area of the agar plate where the bacterial lawn is not present. This is in contrast to animals in normoxia, which lay the majority of their eggs on the bacterial lawn. One hypothesis for this hypoxia-induced egg-laying behavior is that the animal can sense microenvironments in hypoxia. To examine if various pathways are involved with chronic-hypoxia responses RNAi and assayed genetic mutants were used. Specifically, genetic mutations affecting oxygen sensing (egl-9), aerotaxis (npr-1), TFG-ß signaling (dbl-1, daf-7) and predicted oxygen-binding proteins (globin-like genes) were phenotypically analyzed. Results indicate that mutations in several of these genes (npr-1, dbl-1) resulted in a decrease in hypoxia survival rate. A mutation in egl-9 also had a detrimental affect on the viability of an animal raised in chronic hypoxia. However, a similar phenotype was not observed in the vhl-1 mutation indicating that the phenotype may not be due to a mere increase in HIF-1 levels, …
Molecular Basis of Plant Defense Against Aphids: Role of the Arabidopsis Thaliana PAD4 and MPL1 Genes
Myzus persicae (Sülzer), commonly known as green peach aphid (GPA), utilizes its slender stylet to penetrate the plant tissues intercellularly and consume copious amounts of photoassimilates present in the phloem sap causing extensive damage to host plants. The compatible interaction between GPA and Arabidopsis thaliana enabled us to characterize plant response to aphid infestation. Upon GPA infestation, Arabidopsis PAD4 (PHYTOALEXIN DEFICIENT4) gene modulates premature leaf senescence, which is involved in the programmed degradation of cellular components and the export of nutrients out of the senescing leaf. Senescence mechanism is utilized by plants to limit aphid growth. In addition, PAD4 provides antixenosis (deters insect settling and feeding) and antibiosis (impair aphid fecundity) against GPA and adversely impact sieve element availability to GPA. Basal expression of PAD4 contributes to antibiosis, and the GPA-induced expression of PAD4 contributes to antixenosis. Mutation in the Arabidopsis stearoyl-ACP desaturase encoding SSI2 (suppressor of SALICYLIC ACID [SA] insensitivity2) gene that results in an accelerated cell death phenotype and dwarfing, also conferred heightened antibiosis to GPA. Results of this study indicate that PAD4 is required for the ssi2-mediated enhanced antibiosis to GPA. The PAD4 protein contains conserved Ser, Asp and His residues that form the catalytic triad of many α/β fold acyl hydrolases. Arabidopsis plants expressing mutant versions of PAD4 [PAD4(S118A) and PAD4(D178A)] supported higher numbers of GPA as compared to wild type (WT) plants in no-choice tests. Furthermore, Electrical Penetration Graph (EPG) studies revealed that S118 residue in PAD4 is essential to limit GPA feeding from the sieve elements. However, the ability to deter insect settling in choice tests was not impacted by the PAD4(S118A) and PAD4(D178A) mutations, thus suggesting that PAD4s involvement in deterring insect settling and in antibiosis are determined by separate regions of PAD4. The MPL1 (MYZUS PERSICAE INDUCED LIPASE1) gene is another critical …
Bioconcentration of Triclosan, Methyl-Triclosan, and Triclocarban in the Plants and Sediments of a Constructed Wetland
Triclosan and triclocarban are antimicrobial compounds added to a variety of consumer products that are commonly detected in waste water effluent. The focus of this study was to determine whether the bioconcentration of these compounds in wetland plants and sediments exhibited species specific and site specific differences by collecting field samples from a constructed wetland in Denton, Texas. The study showed that species-specific differences in bioconcentration exist for triclosan and triclocarban. Site-specific differences in bioconcentration were observed for triclosan and triclocarban in roots tissues and sediments. These results suggest that species selection is important for optimizing the removal of triclosan and triclocarban in constructed wetlands and raises concerns about the long term exposure of wetland ecosystems to these compounds.
The Ecology and Paleobiogeography of Freshwater Mussels (Family: Unionidae) from Selected River Basins in Texas
This dissertation has two overall objectives: first, to demonstrate the utility of paleozoological data for ongoing and future mussel-conservation efforts in Texas and second, to evaluate whether simple measures of habitat (e.g., water depth, velocity and particle size) are important for demonstrating the within-habitat spatial separation of mussels. Although these topics may seem disparate, both are important for increasing our understanding of unionid ecology and biogeography. Chapters 1 through 3 examine the use of paleozoological data for mussel conservation. Although these types of data are not new they have rarely been used in mussel conservation efforts within Texas. This is unfortunate because paleozoological data can provide an excellent record of the mussel fauna prior to wide-scale modern impacts and in areas where historical survey data are lacking. Chapter 4 examines whether assessments of microhabitat for mussels using simple measures of habitat (e.g., water velocity, depth and particle size) are useful. Recent studies have suggested that these measures do not explain the mussel distribution in flowing streams. If this is correct, instream flow studies using this approach need to be revised. Results of Chapter 4 indicate that mussels in the lower Brazos River basin are constrained in distribution by the availability of heterogenous substrate. Appendix A, details the first account of a living population of Truncilla macrodon, which is a candidate species for the Endangered Species Act (ESA). The population was found while conducting mussel instream flow studies in the lower Brazos River basin.
Reproductive and Growth Responses of the Fathead Minnow (Pimephales Promelas) and Japanese Medaka (Oryzias Latipes) to the Synthetic Progestin, Norethindrone
A commonly prescribed contraceptive, the synthetic progestin norethindrone (NET) inhibits ovulation in humans. However, ecotoxicological data are lacking. Preliminary tests produced an LC50 for NET of > 1.0 mg/L (96-hour, fathead minnow (FHM) and medaka) and a NOEC of 242.0 µg/L, a LOEC of 485.0 µg/L (7-day, growth for FHM and medaka). Reproductive testing revealed a LOEC for fecundity of 24.1 ng/L (21 days, medaka). Further testing confirmed the LOEC of 24.1 ng/L while defining a NOEC of 4.7 ng/L (28 days, medaka). Effect of NET in medaka life-cycle exposure at concentrations exceeding 4.7 ng/L was evident. Few females were present in the 24.7 ng/L exposure concentration, with none in the 104.6 ng/L. Egg production was significantly reduced at concentrations exceeding 4.7 ng/L. Additionally, weight, condition factor and somatic indices were significantly different in males exposed to concentrations exceeding 4.7 ng/L. For fecundity and sexual differentiation; the NOEC was 4.7 ng/L, the LOEC 24.6 ng/L; growth and somatic indices, the NOEC was more appropriately 0.9 ng/L, with effect evident at 4.7 ng/L. Sexual differentiation of the F1 population was similar to the F0. A defining result of this test was development of exceptionally large ovaries in NET- exposed female medaka, perhaps indicative of a threshold limit for exposure in these fish. Results of FHM life-cycle testing were similar, establishing a NOEC for fecundity of 0.9 ng/L, a LOEC of 4.8 ng/L. NET's inhibitory effect on gonadal development was obvious; GSI NOEC for males, 4.8 ng/L, and histological examination confirmed the presence of intersex development at elevated concentrations. Normal physical development and growth were impaired, generally at concentrations exceeding 24.1 ng/L. At exposure concentrations exceeding 4.8 ng/L, external sexual confirmation of fish was difficult; LOEC for finspot development in females, 4.8 ng/L. Sexual determination of the 97.1 ng/L exposure group was …
Anatomical and Morphological Responses of Cardiospermum Halicacabum L. (Balloon Vine), to Four Levels of Water Availability
C. halicacabum (Sapindaceae) is an invasive plant that is considered a nuisance species in Texas riparian environments. Little is known of the tolerance of C. halicacabum to flooding and drought; however, this information may provide insight into the characteristics that contribute to C. halicacabum purported invasiveness. C. halicacabum seedlings (n = 92) were exposed to one of four levels of water availability (flooded, saturated, intermediate and dry) over six weeks under greenhouse conditions. Plant performance was affected by water availability; however, there was no effect on survivorship. Flooded and saturated plants exhibited morphological adaptations; producing adventitious roots, hypertrophy, and aerenchyma tissue. Morphological measures, anatomical responses, and patterns of biomass allocation all indicate that C. halicacabum is able to survive periodic inundation, perform in saturation, and establish and thrive on the drier end of a moisture gradient.
Retinoic acid Treatment Affects Kidney Development and Osmoregulatory System in the Developing Chicken (Gallus Gallus)
Development is a dynamic process characterized by critical periods in which organ systems are sensitive to changes in the surrounding environment. In the current study, critical windows of embryonic growth and kidney development were assessed in the embryonic chicken. All&#8208;trans retinoic acid (tRA) influences not only organogenesis and cell proliferation, but also targets metanephric kidney nephrogenesis. Embryonic chickens were given a single injection of tRA on embryonic day 8. tRA decreased embryo, kidney, and heart mass from day 16 to day 18. However, mass specific kidney and heart masses showed no differences. Whole blood, plasma, and allantoic fluid osmolality were altered in tRA treated embryos from day 16 to day 18. In addition, hematocrit, red blood cell count, and hemoglobin concentration were altered in tRA treated embryos. The results suggest that although nephrogenesis was not affected by tRA, the developing osmoregulatory system was altered in tRA treated embryos.
Characterization of Triclocarban, Methyl- Triclosan, and Triclosan in Water, Sediment, and Corbicula Fluminea (Müller, 1774) Using Laboratory, in Situ, and Field Assessments
In the last decade emerging contaminants research has intensified in a bid to answer questions about fate, transport, and effects as these chemicals as they get released into the environment. The chemicals of interest were the antimicrobials; triclocarban (TCC) and triclosan (TCS), and a metabolite of triclosan, methyl triclosan (MTCS). This research was designed to answer the question: what is the fate of these chemicals once they are released from the waste water treatment plant into receiving streams. Three different assessment methods; field monitoring, in-situ experiments, and laboratory studies were used to answer the overall question. TCS, TCC, and MTCS levels were measured in surface water, sediment and the Asiatic clam Corbicula fluminea. Field studies were conducted using four sites at Pecan Creek, Denton TX. Levels of all three chemicals in clams were up to fives orders of magnitude the water concentrations but an order of magnitude lower than in sediment. Highest sediment levels of chemicals were measured in samples from the mouth of Pecan Creek (highest organic matter). TCC was the most and TCS was the least accumulated chemicals. In-situ and lab studies both indicated that uptake of these chemicals into the clams was very rapid and measurable within 24hours of exposure. The after clams were transferred into clean water most of the compounds were depurated within 14 days.
Museum education: Creation, implementation, and evaluation of a web-based Elm Fork Natural Heritage Museum
Evaluation of museum audiences both in their physical and web-based spaces is a necessary component of museum education. For smaller museums without the personnel or knowledge to create a website and evaluate the on-line audience, using a web-based learning tool may be able to help these museums properly maintain an online site. A web-based Elm Fork Natural Heritage Museum (WBEFNHM) was created during the 2008 fall semester at the University of North Texas. The site included photographs and information from specimens housed within the physical Elm Fork Natural Heritage Museum. The site was available to three non-science majors' biology laboratory courses, and three science majors' biology laboratory courses during the 2009 spring and fall semesters. Student use of the WBEFNHM was tracked and found no significant difference between the amount of time science majors and non-majors spent on the site. This evaluation helps in understanding future use of an online EFNHM.
Solvent Effects and Bioconcentration Patterns of Antimicrobial Compounds in Wetland Plants
This study looked at effects of organic solvents dimethylsulfoxide, dimethylformamide and acetone at 0.01%, 0.05% and 0.1% concentration on germination and seedling development wetland plants. Even at 0.01% level, all solvents affected some aspect of seed germination or seedling growth. Acetone at 0.01% was least toxic. Root morphological characteristics were most sensitive compared to shoot morphological characteristics. This study also looked at bioconcentration patterns of antimicrobial compounds triclosan, triclocarban and methyl-triclosan in wetland plants exposed to Denton Municipal Waste Water Treatment Plant effluent. Bioconcentration patterns of antimicrobial compounds varied among species within groups as well as within organs of species. The highest triclocarban, triclosan and methyltriclosan concentration were in shoot of N. guadalupensis, root of N. lutea and in shoots of P. nodous respectively.
Purification of Cyanide-Degrading Nitrilase from Pseudomonas Fluorescens NCIMB 11764.
Cyanide is a well known toxicant that arises in the environment from both biological and industrial sources. Bacteria have evolved novel coping mechanisms for cyanide and function as principal agents in the biosphere for cyanide recycling. Some bacteria exhibit the unusual ability of growing on cyanide as the sole nitrogen source. One such organism is Pseudomonas fluorescens NCIMB 11764 (Pf11764) which employs a novel oxidative mechanism for detoxifying and assimilating cyanide. A unique complex of enzymes referred to as cyanide oxygenase (CNO) is responsible for this ability converting cyanide to ammonia which is then assimilated. Because one component of the four member CNO complex was previously shown to act on cyanide independent of the other members, its characterization was sought as a means of gaining a better understanding of the overall catalytic mechanism of the complex. Preliminary studies suggested that the enzyme belonged to a subset of nitrilase enzymes known as cyanide dihydratases (CynD), however, a cynD-like gene in Pf11764 could not be detected by PCR. Instead, a separate nitrilase (Nit) linked to cyanide metabolism was detected. The corresponding nit gene was shown to be one of a conserved set of nit genes traced to a unique cluster in bacteria known as Nit1C. To determine whether the previously described CynD enzyme was instead Nit, efforts were undertaken to isolate the enzyme. This was pursued by cloning and expressing the recombinant enzyme and by attempting to isolate the native enzyme. This thesis is concerned with the latter activity and describes the purification of a Nit-like cyanide-degrading nitrilase (NitCC) from Pf11764 to ~95% homogeneity. Purification was greatly facilitated by the discovery that fumaronitrile, as opposed to cyanide, was the preferred substrate for the enzyme (20 versus 1 U/mg protein, respectively). While cyanide was less effective as a substrate, the specificity for cyanide …
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