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 Degree Discipline: Biology
A High-fat Meal Alters Post-prandial Mrna Expression of Sirt1, Sirt4, and Sirt6
Sirtuins (SIRT) regulate the transcription of various genes involved in the development of diet-induced obesity and chronic disease; however, it is unknown how they change acutely following a high-fat meal. The purpose of this study was to determine the effect of a high-fat meal (65% kcals/d; 85% fat recommendation), on SIRT1-7 mRNA expression in blood leukocytes at 1, 3, and 5-h post-prandial. Men and women (N=24) reported to the lab following an overnight fast (>12H). Total RNA was isolated and reverse transcribed prior to using a Taqman qPCR technique with 18S rRNA as a normalizer to determine SIRT1-7 mRNA expression. An additional aliquot of serum was used to measure triglycerides. Data was analyzed using a RM ANOVA with P<0.05. Triglycerides (P<0.001; 124%) peaked at 3-h. SIRT 1 (P=0.004; 70%), and SIRT 6 (P=0.017; 53%) decreased expression at 3-h. SIRT4 (P=0.024) peaked at 5H relative to baseline (70%) and 3-h (68%). To our knowledge, this is the first study to report that consumption of a high-fat meal transiently alters SIRT mRNA expression consistent in a pattern that mirrors changes in serum triglycerides. Decrease in expression of SIRT1 and SIRT6 combined with an increased SIRT4 would be consistent with an increase in metabolic disease risk if maintained on a chronic basis. digital.library.unt.edu/ark:/67531/metadc822825/
The Effect of Post-exercise Ethanol Consumption on the Acute Hormonal Response to Heavy Resistance Exercise in Women
The purpose of this study was to examine the hormonal response to acute ethanol ingestion following a bout of heavy resistance exercise in women. Eight resistance trained women completed two identical acute heavy resistance exercise tasks (AHRET). From 10-20 minutes post-AHRET, participants consumed either a grain ethanol or a placebo beverage. Blood was collected before (PRE) and immediately after the AHRET (IP) and then every 20 minutes for five hours. Blood collected after beverage ingestion was pooled into 3 batches (phases: 20-40 minutes, 60-120 minutes, and 140-300 minutes post-exercise) and analyzed for serum total testosterone (TT), free testosterone (FT), insulin-like growth factor-I (IGF-I), human growth hormone (GH), cortisol (COR), and estradiol (E2) concentrations. Circulating concentrations of TT were significantly greater at P20-40 than at PRE, P60-120, and P140-300. Circulating concentrations of FT were significantly greater at P20-40 than at all other times. Circulating concentrations of GH were significantly greater at IP than at PRE, P60-120, and P140-300. Circulating concentrations of COR were significantly greater at P20-40 than at all other times. Additionally, COR concentrations at P140-300 were significantly lower than at all other times. Circulating concentrations of IGF-1 were significantly greater at P20-40 than at P60-120 and P140-300. Circulating concentrations of E2 were significantly greater at P20-40 than at all other times. In summary, the present study demonstrated an acute modulation of the neuroendocrine milieu following a heavy resistance exercise bout in women. Ethanol ingestion appeared to have no significant effect on the characteristics of acute hormonal augmentation in TT, FT, GH, COR, IGF-1, or E2. digital.library.unt.edu/ark:/67531/metadc822770/
Characterizing the Molecular Changes of Austrofundulus Limnaeus As It Develops Towards and Enters Diapause Ii
Austrofundulus limnaeus is a species of annual killifish which inhabits ephemeral ponds in South America. The species is able to survive seasonally desiccating ponds due to their ability to produce robust embryos. The embryos of this species are capable of entering a developmental arrest, termed diapause II, which precedes the onset of drought. While in this arrested state embryos exhibit the greatest tolerance to anoxia of any characterized vertebrate at 25ºC. Furthermore, when raised at 30ºC, embryos escape the entrance to diapause II and go on to develop directly. Currently, little is known about the molecular mechanisms which induce and maintain this developmentally arrested state. In this study I have developed methods to analyze changes in histone modifications in the context of diapause II. Histone modifications were chosen due to their extreme conservation and well characterized role as modulators of gene expression in other systems. Results utilizing adapted immunobased assays show significant changes in the global amount of H3S10P, H3K27me and H3K4me, as the embryos progress from early embryogenesis through the exit of diapause. Additionally, it is revealed that there exists a degree of phenotypic plasticity with regards to the entrance into diapause II which is modulated by the environment (severe hypoxia 0.1% O2). This work builds a foundation for future histone modification studies and contributes the development of several tools to the field. This study contributes to a greater molecular understanding of the cue(s) which influence the remarkable phenomenon of obligate developmental arrest in a vertebrate embryo. digital.library.unt.edu/ark:/67531/metadc822736/
Environmental Modulation of the Onset of Air-breathing of the Siamese Fighting Fish and the Blue Gourami
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This study determined the effect of hypoxia on air-breathing onset and physiological and morphological characters in larvae of the air breathing fishes Trichopodus trichopterus and Betta splendens. Larvae were exposed intermittently (12/12 h daily) to 20, 17, and 14 kPa of PO2 from 1 to 40 days post-fertilization. Survival, onset of air breathing, wet body mass, O2, Pcrit were measured every 5 dpf. Hypoxia advanced by 4 days, and delayed by 9 days, the onset of air breathing in Betta and Trichopodus, respectively. Hypoxia increased larval body length, wet mass, and labyrinth organ respiratory surface of Betta, but did not affect these factors in Trichopodus. Hypoxic exposure increased O2 by 50-100% at each day throughout larval development in Betta, but had no effect on larval Trichopodus. Hypoxia decreased Pcrit in Betta by 37%, but increased Pcrit in Trichopodus by 70%. Larval Betta reared in hypoxia showed a modified heart rate:opercular rate ratio (3:1 to 2:1), but these changes did not occur in Trichopodus. Compared to Betta, the blood of Trichopodus had a higher P50 and much smaller Bohr and Root effects. These interspecific differences are likely due to ecophysiological differences: Betta is a non- obligatory air-breather after 36 dpf with a slow lifestyle reflected in its low metabolism, while Trichopodus is an obligatory air-breather past 32 dpf with an athletic fast lifestyle and accompanying high metabolism. digital.library.unt.edu/ark:/67531/metadc822746/
Phenotypic Morphological Plasticity Induced by Environmental Salt Stress in the Brine Shrimp, Artemia Franciscana
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. digital.library.unt.edu/ark:/67531/metadc822750/
The Role of Cysteinyl Leukotriene Receptor 2 in Thrombocyte Aggregation
Cysteinyl leukotriene receptor 2, a G-protein coupled receptor known to be expressed and functional on human platelets. However, it seems that upon ligand activation the cysteinyl leukotriene receptor 2 activates a variety of signaling pathways in multiple cell types among different species. Previously, a former laboratory member Vrinda Kulkarni found cysteinyl leukotriene receptor 2 to be expressed on the surface of adult zebrafish thrombocytes. In this work I studied the characteristics of aggregation in adult zebrafish thrombocytes with the knockdown of cysteinyl leukotriene receptor 2. I used a newly developed knockdown method to study the function of cysteinyl leukotriene receptor 2. Knockdown of the cysteinyl leukotriene was confirmed using RT-PCR results showed p=.001, reduced sell surface level of expression of the cysteinyl leukotriene receptor 2 results showed that p=.002. I found that the knockdown of cysteinyl leukotriene receptor 2 results in prothrombotic thrombocytes by using flow cytometry p=.0001. digital.library.unt.edu/ark:/67531/metadc822817/
Impact of a Genetically Engineered Probiotic Therapy and Igf-1 Genomics in the Pahenu2 Mouse Model of Pku
Absence of functional phenylalanine hydroxylase results in phenylketonuria (PKU). Viable treatments remain few, expensive and secondary conditions such as osteopenia occur in most PKU patients. Objective 1: Given the recently described roles of gut microbes to aid host digestion, an orally administered genetically engineered probiotic as the delivery vehicle for enzyme replacement therapy was created. The engineered probiotic, pHENOMMenal, produced phenylalanine ammonia lyase with significant production of trans-cinnamate (phenylalanine cleavage product) in vitro and resulted in a reduction of 515 μM in blood phenylalanine when fed to PKU animals for 14 days (from 2307µM ± 264µM to 1792µM ± 261µM, n = 6, P < 0.05). The control probiotic produced no change in blood phenylalanine. Thus, pHENOMMenal treatment in PKU mice demonstrated engineered microbes could compensate for a metabolic deficiency of the host. Objective 2: Evaluate the PAHenu2 mouse model of PKU for a genetic discrepancy causing ocular enlargement and delayed development observed only after the PAHenu2 mutation was crossed to the C57BL/6J mouse. When compared to healthy littermates, ELISA indicated a consistent but insignificant decrease in plasma IGF-1 and an increase in ocular IGF-1 in PKU animals. SNP screening demonstrated a differential inheritance of IGF-1 alleles in healthy and PKU animals based on PAH allele inheritance. Ocular and developmental phenotypes in the PAHenu2 colony match those described in previous IGF-1 studies. Understanding the IGF-1 inheritance discrepancy will enable better osteopenia research using PAHenu2 mice and allow breeding of a healthier mouse colony for continued research. Collectively the results from this work describe a new therapeutic approach for treatment of PKU as well as a better understanding of the PAHenu2 mouse model to study this disease. digital.library.unt.edu/ark:/67531/metadc822730/
Thresholds and Legacy Effects of Tropical Floodplain Fish Assemblages in Response to Flood Attributes
Natural flow regimes are critical for sustaining biodiversity and river integrity. Floods and droughts form an important component of river systems and control population sizes and species diversity across space and time. Modification of flow regimes, including disruption of the timing, magnitude and duration of flooding, is a global problem, and many new impoundments are planned for large river-floodplain ecosystems in the tropics. Flow modifications may cause dramatic non-linear responses in population sizes and have lasting effects through time, but such topics are poorly investigated over multi-year scales, especially in highly diverse tropical ecosystems. Using a long-term dataset from the Upper Paraná River floodplain, Brazil, I tested for threshold and legacy effects of fish assemblages to flood attributes, such as timing, magnitude, duration, rate of change and variation. Specifically, I hypothesized that long duration, high magnitude floods would elicit threshold responses in long-distance migratory fish species and these responses result in significant legacy effects detectable over multiple years. Consistent positive threshold responses to increasing flood duration and magnitude were detected for many species and not significantly correlated with reproductive guilds. Legacy effects were prevalent (i.e. identified for more than 90% of species) and including flood attributes from previous years increased variance explained in species abundances by 15-20% compared to contemporary flood attributes alone. Contrary to my hypotheses, flood duration did not elicit strong legacy effects and species from the same reproductive guild did not have similar legacy effects models. The prevalence of legacy effects across almost all species in this diverse study system highlights the need to consider such dynamics in other systems. My results provide targets for management and conservation actions, such as environmental flow releases from upstream reservoirs. Environmental flows releases may play a significant role in sustainability of the floodplain and other tropical floodplain ecosystems affected by impoundments. digital.library.unt.edu/ark:/67531/metadc822800/
Effect of Acute Alcohol Ingestion on Resistance Exercise Induced Mtorc1 Signaling in Human Muscle
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The purpose of this project was to further elucidate the effects post-exercise alcohol ingestion. This project had many novel aspects including using a resistance exercise (RE) only exercise design and the inclusion of women. To our knowledge, we are the first to investigate the effect of post-RE alcohol ingestion in women. In the first chapter of this project, information on the prevalence of alcohol use and the importance of skeletal muscle as a dynamic and metabolic tissue was provided. In chapter two, the effects of post-RE alcohol ingestion in men and women are detailed. The major findings of this study was that although RE elicited similar mTORC1 signaling both in men and in women, alcohol ingestion appeared to only attenuate RE-induced phosphorylation of the mTORC1 signaling pathway in men. The third chapter focused on examining the effects of post-RE alcohol ingestion on acute testosterone bioavailability. The primary findings of this study was that alcohol substantially elevated serum total and free testosterone concentrations during recovery from a bout of resistance exercise. The fourth chapter detailed factors that contribute to bone density in men. The major findings of this study was that young adult male long-distance runners who participated in resistance training at least once per week had greater bone mineral density than their non-resistance trained and non-exercise trained peers. digital.library.unt.edu/ark:/67531/metadc804831/
Glucose Induces Sensitivity to Oxygen Deprivation and Alters Gene Expression in Caenorhabditis Elegans
An organisms’ diet represents an exogenous influence that often yields colossal effects on long-term health and disease risk. The overconsumption of dietary sugars for example, has contributed to significant increases in obesity and type-2 diabetes; health issues that are costly both economically and in terms of human life. Individuals who are obese or are type-2 diabetic often have compromised oxygen delivery and an increased vulnerability to oxygen-deprivation related complications, such as ischemic strokes, peripheral arterial disease and myocardial infarction. Thus, it is of interest to identify the molecular changes glucose supplementation or hyperglycemia can induce, which ultimately compromise oxygen deprivation responses. By utilizing the Caenorhabditis elegans genetic model system, which is anoxia tolerant, I determined that a glucose-supplemented diet negatively impacts responses to anoxia and that the insulin-like signaling pathway, through fatty acid and ceramide biosynthesis and antioxidant activity, modulates anoxia survival. Additionally, a glucose-supplemented diet induces lipid accumulation. Use of RNA-sequencing analysis to compare gene expression responses in animals fed either a standard or glucose-supplemented diet revealed that glucose impacts the expression of genes involved with multiple cellular processes including lipid and carbohydrate metabolism, stress responses, cell division, and extracellular functions. Several of the genes we identified are homologous to human genes that are differentially regulated in response to metabolic diseases, suggesting that there may be conserved gene expression responses between C. elegans supplemented with glucose and a diabetic and/or obese state observed in humans. These findings support the utility of C. elegans to model specific aspects of the T2D disease process (e.g., glucose-induced sensitivity to oxygen deprivation) and identify potentially novel regulators of common complications seen in hyperglycemic and T2D patients (e.g., macrovascular complications). digital.library.unt.edu/ark:/67531/metadc804958/
Characteristics of Primary Cilia and Centrosomes in Neuronal and Glial Lineages of the Adult Brain
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Primary cilia are sensory organelles that are important for initiating cell division in the brain, especially through sonic hedgehog (Shh) signaling. Several lines of evidence suggest that the mitogenic effect of Shh requires primary cilia. Proliferation initiated by Shh signaling plays key roles in brain development, in neurogenesis in the adult hippocampus, and in the generation of glial cells in response to cortical injury. In spite of the likely involvement of cilia in these events, little is known about their characteristics. Centrosomes, which are associated with primary cilia, also have multiple influences on the cell cycle, and they are important in assembling microtubules for the maintenance of the cell’s cytoskeleton and cilia. The cilia of terminally differentiated neurons have been previously examined with respect to length, incidence, and receptors present. However, almost nothing is known about primary cilia in stem cells, progenitors, or differentiated glial cells. Moreover, it is not known how the properties of cilia and centrosomes may vary with cell cycle or proliferative potential, in brain or other tissues. This dissertation focuses first on neurogenesis in the hippocampal subgranular zone (SGZ). The SGZ is one of the few brain regions in mammals that gives rise to a substantial number of new neurons throughout adulthood. The neuron lineage contains a progression of identifiable precursor cell types with different proliferation rates. This present study found that primary cilia were present in every cell type in the neuronal lineage in SGZ. Cilium length and incidence were positively correlated among these cell types. Ciliary levels of adenylyl cyclase type III (ACIII) levels relative to ADP-ribosylation factor-like protein 13b (Arl13b) was higher in neurons than in precursor cells and glia, and also changed with the cell cycle. G-protein coupled receptors, SstR3, MCHR1, and Gpr161 receptors were only found in neuronal cilia. The levels and distribution of three centrosomal proteins, γ-tubulin, pericentrin and cenexin in neurons was different from the distributions in precursors and glia. The second focus of study is glial responses to injury in the neocortex, which has been widely studied as an injury model. This study found that in the normal adult somatosensory cortex, primary cilia were present in astrocytes and polydendrocytes but not in microglia. Following injury, the incidence of primary cilia decreased in astrocytes. Also, a new cell type expressing GFAP, NG2 and Olig2 was seen 3 days following injury, but was not present in normal mice. The characteristics of primary cilia and centrosome described here suggest that in stem cells and progenitors their characteristics may be well suited for proliferation, whereas in neurons, the cilia and centrosomes are important for other sensory functions. digital.library.unt.edu/ark:/67531/metadc801939/
Cytotoxicity and Functional Toxicity of Mefloquine and Search for Protective Compounds
Mefloquine hydrochloride is an antimalarial agent that has been used for the past 40 years. Numerous reports of neurological side effects have recently led the FDA to issue a strong warning regarding long-term neurological effects. This warning lead to the U.S. Army’s Special Forces and other components to discontinue its use in July of 2013. Despite reported adverse side effects, mefloquine remains in circulation and is recommended to travelers going to specific Asian countries. Mefloquine has been used as a treatment for those already infected with the malaria parasite (blood concentrations ranging from 2.1 to 23 µM), and as prophylaxis (blood concentrations averaging 3.8 µM) (Dow 2003). The purpose of this study was to quantify Mefloquine’s toxicity using spontaneously active nerve cell networks growing on microelectrode arrays in vitro and to identify compounds that alleviate or reduce toxic effects. The current literature on mefloquine toxicity is lacking electrophysiological data. These data will contribute to research on the mechanism of adverse side effects associated with mefloquine use. Sequential titration experiments were performed by adding increasing concentrations of mefloquine solution to cultured neurons. Network responses were quantified and reversibility was examined. In each network, activity decreases were normalized as a percent of reference activity yielding a mean IC50 value of 5.97 ± 0.44 (SD) µM (n=6). After total activity loss, no activity was recovered with two successive medium changes. To test for network response desensitization resulting from sequential applications over 5-6 hr periods, one-point titrations at varying concentrations were conducted with fresh networks. These experiments yielded a single concentration response curve with an IC50 value of 2.97 µM. This represents a statistically significant shift (p < 0.0001) to lower concentrations of mefloquine, demonstrating that sequential applications result in network desensitization. After mefloquine exposures, cells were evaluated for irreversible cytotoxic damage. Over a 12-hour period under 6 µM mefloquine, process beading and granulation of somal cytoplasm were observed. At 8 µM mefloquine cell stress was apparent after only 10 minutes with major glial damage and process beading at 120 minutes. In this study, quinolinic acid served as a neuroprotectant at 20 µM. There have been multiple studies on the endogenous concentrations of quinolinic acid and current literature is quite variable. Immunocompromised individuals have some of the highest blood levels of quinolinic acid (up to 20 µM). With 30 min pre-applications of quinolinic acid, the mefloquine IC50 value shifted from 5.97 ± 0.44 µM (n=6), to 9.28 ± 0.55 µM (n=3). This represents a statistically significant change to higher mefloquine concentrations and demonstrates neuroprotection. digital.library.unt.edu/ark:/67531/metadc801913/
The Effect of Curcumin Supplementation on Physical and Biological Indices of Delayed Onset Muscle Soreness and Inflammation Following Muscle Injury
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In this project, the effects of dietary polyphenols on exercise-induced muscle damage and vascular health are examined. Dietary polyphenols exert well-known anti-inflammatory effects; however, how these effects are realized with respect to vascular health and EIMD is relatively unknown. I begin by reviewing the available literature surrounding the impact of three dietary polyphenols (curcumin, catechins, and quercetin) on inflammation associated with EIMD. It is well established that their primary means of anti-inflammation is through alterations of NF-κB and AP-1 transcription activities. Given this, their inclusion into training strategies seems reasonable. Consistent evidence is presented making a case for the anti-inflammatory effects of dietary polyphenols following EIMD. I follow this review up by completing an in-depth study on the consumption of curcumin prior to EIMD. I found curcumin (1000 mg/day) can reduce subjective soreness and decrease inflammation compared to placebo controls. To further understand the effects of dietary polyphenols on health, I investigate the effects of a four-week supplementation period of cocoa (catechins) on vascular. I concluded that atherogenic risk in obese women is reduced after consumption of cocoa. In addition to these experimental projects, I developed two novel methods that can be used to investigate vascular health (EMP concentration) and intracellular protein and mRNA production using flow cytometry. digital.library.unt.edu/ark:/67531/metadc801906/
Understanding Microbial Biodegradation of Environmental Contaminants
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The accumulation of industrial contaminants in the natural environments have rapidly become a serious threat for human and animal life. Fortunately, there are microorganisms capable of degrading or transforming environmental contaminants. The present dissertation work aimed to understand the genomic basis of microbial degradation and resistance. The focus was the genomic study of the following bacteria: a) Pseudomonas fluorescens NCIMB 11764, a unique bacterium with specific enzymes that allow cyanide adaptation features. Potential cyanide degradation mechanisms found in this strain included nit1C cluster, and CNO complex. Potential cyanide tolerance genes found included cyanide insensitive oxidases, nitric oxide producing gene, and iron metabolism genes. b) Cupriavidus sp. strain SK-3 and strain SK-4. The genome of both bacteria presented the bph operon for polychlorinated biphenyl (PCB) degradation, but we found differences in the sequences of the genes. Those differences might indicate their preferences for different PCB substrates. c) Arsenic resistant bacterial communities observed in the Atacama Desert. Specific bacteria were found to thrive depending on the arsenic concentration. Examples were Bacteroidetes and Spirochaetes phyla whose proportions increased in the river with high arsenic concentrations. Also, DNA repair and replication metabolic functions seem to be necessary for resistance to arsenic contaminated environments. Our research give us insights on how bacteria communities, not just individually, can adapt and become resistant to the contaminants. The present dissertation work showed specific genes and mechanisms for degradation and resistance of contaminants that could contribute to develop new bioremediation strategies. digital.library.unt.edu/ark:/67531/metadc801956/
Improving Processing Efficiency for Forensic DNA Samples
The goal of this project was to reduce processing time for forensic DNA testing without incurring significant added costs and/or the need for new instrumentation, while still generating high quality profiles. This was accomplished by: 1) extraction normalization using the ChargeSwitch® Forensic DNA Purification Kit such that a small range of DNA concentrations was consistently obtained, eliminating the need for sample quantification and dilution; 2) developing fast PCR protocols for STR primer sets using shorter amplification methods, low volume reactions and non-fast thermal cyclers; and 3) developing a quicker 3130xl Genetic Analyzer detection method using an alternative polymer/array length combination. Extraction normalization was achieved through a reduction in bead quantity, thereby forcing an increase in bead binding efficiency. Four products (AmpliTaq Gold® Fast PCR Master Mix, KAPA2G™ Fast Multiplex PCR Kit, SpeedSTAR™ HS DNA Polymerase and Type-it Microsatellite PCR Kit) were evaluated for low volume (3μl) fast PCR on a 384-well Veriti® thermal cycler with the Identifiler primer set. KAPA2G™ was selected for 3μl fast PCR protocols using PowerPlex 16 HS and Identifiler Plus primer sets (42-51min), as well as 5μl and 6μl Identifiler fast reactions on a 9700 thermal cycler (51-60min). Alternative detection (POP-6™/22cm) achieved 24-28min run times, but with decreased resolution as compared to traditional POP-4®/36cm detection for alleles >200bp; however, 1bp resolution was still obtainable for alleles <300bp. These modifications resulted in robust databasing processes with up to a 37% reduction in processing time for buccal swabs and Buccal DNA Collectors™ using the three primer sets evaluated (3μl fast PCR reactions) and generated high quality STR profiles with ≥90% pass rates. digital.library.unt.edu/ark:/67531/metadc799515/
Neurotoxicity of the Industrial Solvent 4-Methylcyclohexanemethanol: Involvement of the GABA Receptor
A recent chemical spill of 4-Methylcyclohexanemethanol (4-MCHM) in West Virginia left 300,000 people without water. Officials claimed that this compound is not lethally toxic, but potentially harmful if swallowed or inhaled, and can cause eye and skin irritation. Sittig's Handbook of Toxic and Hazardous Chemical Carcinogens reports high exposures from skin contact or inhalation may cause damage to the heart, liver, kidneys, and lungs, and may result in death. However, no quantitative data seem to exist and no references can be found on neurotoxicity. We have investigated the neurotoxicity of 4-MCHM using mammalian nerve cell networks grown on microelectrode arrays. Network spontaneous activity from multiple units (range 48 – 120 per network) were used as the primary readout. Individual units were followed based on spike waveforms digitized at 40 kHz (Plexon MNAP system). Dose response curves show the effective inhibitory concentration at 50 percent decrease (EC50) to average 27.4 microM SD±6.17. However, in the presence of 40 microM bicuculline, a competitive GABAA antagonist, the EC50 shifts to 70.63uM SD ±4.3; implying that early, low concentration exposures to 4-MCHM involve GABA activation. Initial activity loss occurs without active unit loss (defined as 10 or more template threshold crossing per min), indicating functional interference with spike production. Full recovery has not been seen at concentrations above 130 microM, unless the culture was given bicuculline. Direct exposure to 400uM results in immediate, irreversible loss of spike production, followed by necrosis of glia and neurons. digital.library.unt.edu/ark:/67531/metadc799542/
Women Have Higher Skin Temperature on the Back during Treadmill Exercise in a Hot, Humid Environment
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A common measurement of body temperature during exercise in a hot, humid environment is mean skin temperature collected from 3-12 sites on the body. However, such an approach fails to demonstrate localized differences in skin temperature that are likely to exist as a function of gender. The purpose of this study was to examine potential differences in skin temperature between men and women at 17 different locations on the body. Young women (21 ± 1 y; n = 11) and men (23 ± 3; n = 10) were recruited to complete a 60-min walk/jog interval protocol in a hot (34 ± 1 °C), humid (64 ± 8%) environment while skin temperature was measured. Data was analyzed using a repeated-measures ANOVA (p < 0.05) and location of interaction effects determined using a Fisher’s least squares difference test. We observed a higher change (p < 0.05) from baseline skin temperatures (ΔTsk) for women in three locations: left upper back (women: avg. ΔTsk = 4.12 ± 0.20 °C; men: avg. ΔTsk = 2.70 ± 0.10 °C), right upper back (women: avg. ΔTsk = 4.19 ± 0.07 °C; men: avg. ΔTsk = 2.92 ± 0.05 °C), and right mid-back (women: avg. ΔTsk = 4.62 ± 0.14 °C; men: avg. ΔTsk =3.55 ± 0.09 °C). Individual time differences between genders occurred after 7- (left upper back) and 15-min (right upper back, right mid-back) of exercise and were maintained until the end of exercise. Women have a greater increase in skin temperature at three locations on the back following the onset of exercise in a hot, humid environment. This report provides important information regarding the implications of women exercising in a hot, humid environment. digital.library.unt.edu/ark:/67531/metadc794927/
In Vitro Investigations of Antibiotic Influences on Nerve Cell Network Responses to Pharmacological Agents
Neuronal networks, derived from mouse embryonic frontal cortex (FC) tissue grown on microelectrode arrays, were used to investigate effects of gentamicin pretreatment on pharmacological response to the L-type calcium channel blocker, verapamil. Gentamicin is a broad spectrum antibiotic used to control bacterial contamination in cell culture. The addition of gentamicin directly to medium affects the pharmacological and morphological properties of the cells in culture. A reproducible dose response curve to verapamil from untreated cultures was established and the mean EC50 was calculated to be 1.5 ± 0.5 μM (n=10). 40 μM bicuculline was added to some cell cultures to stabilize activity and verapamil dose response curves were performed in presence of bicuculline, EC50 1.4 ± 0.1 μM (n=9). Statistical analysis showed no significant difference in verapamil EC50s values obtained in presence of bicuculline and hence the data was combined and a standard verapamil EC50 was calculated as 1.4 ± 0.13 μM (n=19). This EC50 was then used to compare verapamil EC50s obtained from neuronal cell cultures with chronic and acute exposures to gentamicin. FC cultures (21- 38 days old) were found to be stable in presence of 2300 μM gentamicin. The recommended concentration of gentamicin for contamination control is 5uL /1 ml medium (108 μM). At this concentration, the verapamil EC50 shifted from 1.4 ± 0.13 μM to 0.9 ± 0.2 μM. Given the limited data points and only two complete CRCs, statistical comparison was not feasible. However, there is a definite trend that shows sensitization of cells to verapamil in presence of gentamicin. The cultures exposed to 108 μM gentamicin for 5 days after seeding showed loss of adhesion and no data could be collected for pharmacological analysis. To conclude, acute gentamicin exposure of neuronal cell cultures causes increased sensitivity to verapamil and chronic or long term exposure to gentamicin may cause loss of adhesion of the cell culture by affecting the glial growth. The effect of chronic exposure to gentamicin on pharmacological responses to verapamil remains inconclusive. digital.library.unt.edu/ark:/67531/metadc699991/
The Impact of Developmental Stress on Cardiovascular Physiology of Two Archosaur Species: American Alligator (Alligator Mississippiensis) and Domestic Chicken (Gallus Gallus)
Crocodilians and birds comprise sister taxa of archosaurs, the development of these vertebrates occurs within an egg case that leaves developing embryos susceptible to fluctuations in the nesting environment. Studies suggest that sub-optimal conditions alter morphological growth and cardiovascular physiology. Regulation of the cardiovascular system is immature in the subjects studied, and embryos may rely on humoral rather than neural control of the cardiovascular system. The primary focus of this dissertation was to assess regulatory mechanisms responsible for maintenance of arterial pressure and heart rate. Dehydration stress had marked effects on embryo growth, and altered baseline cardiovascular parameters, while leaving the response to humoral regulator, angiotensin II (Ang II), unaffected. However, dehydrated alligator embryos developed cholinergic tone on heart rate. Hypoxic incubated chicken embryos were reduced in embryo mass, and altered response to humoral regulatory components Ang I and adenosine in addition identifying a novel regulatory component of the cardiovascular response to acute hypoxia. Collectively, these studies add to the existing knowledge of cardiovascular physiology in embryonic archosaurs and suggest that some components of cardiovascular regulation are plastic following developmental stress. digital.library.unt.edu/ark:/67531/metadc699922/
Optimization of Novel Culturing and Testing Procedures for Acute Effects on Acartia Tonsa and Tisbe Biminiensis
Copepods comprise an ecologically important role in freshwater and marine ecosystems, which is why they are often considered an important ecotoxicological model organism. The International Organization for Standardization’s (ISO) 14669 protocol is the only guideline for the determination of acute toxicity in three European marine copepod species: Acartia tonsa. The goal of this project was to assess the feasibility of establishing and maintaining cultures of Acartia tonsa, as well as to refine current culturing and egg separation methods. Initial culture methodology proved difficult for consistent production of eggs and collection of nauplii. The development of an airlift system for the separation of eggs from nauplii and adults, based on size, successfully increased the availability of eggs, nauplii and adults. The sensitivity and relative conditions of the copepod species was assessed by running a series of 48h acute toxicity tests with the reference toxicants 3,5-dichlorophenol, 4,4’-methylenebis(2,6-di-tert-butylphenol. The acute 48 hour median lethal dose concentration (LC50), the no observed effect concentration (NOEC), and the lowest observed effect concentration (LOEC) was analyzed for the three reference compounds for of A. tonsa. digital.library.unt.edu/ark:/67531/metadc699989/
Measuring Biomarkers From Dried Blood Spots Utilizing Bead-based Multiplex Technology
Dried blood spots is an alternative method to collect blood samples from research subjects. However, little is known about how hemoglobin and hematocrit affect bead-based multiplex assay performance. The purpose of this study was to determine how bead-based multiplex assays perform when analyzing dried blood spot samples. A series of four experiments outline the study each with a specific purpose. A total of 167 subject samples were collected and 92 different biomarkers were measured. Median fluorescence intensity results show a positive correlation between filtered and non-filtered samples. Utilizing a smaller quantity of sample results in a positive correlation to a larger sample. Removal of hemoglobin from the dried blood spot sample does not increase detection or concentration of biomarkers. Of the 92 different biomarkers measured 56 were detectable in 100-75% of the attempted samples. We conclude that blood biomarkers can be detected using bead-based multiplex assays. In addition, it is possible to utilize a smaller quantity of sample while avoiding the use of the entire sample, and maintaining a correlation to the total sample. While our method of hemoglobin was efficient it also removed the biomarkers we wished to analyze. Thus, an alternative method is necessary to determine if removing hemoglobin increases concentration of biomarkers. More research is necessary to determine if the biomarkers measured in this study can be measured over time or within an experimental model. digital.library.unt.edu/ark:/67531/metadc699876/
The Effects of Inbreeding on Fitness Traits in the Critically Endangered Attwater’s Prairie-chicken
The goals of captive breeding programs for endangered species include preserving genetic diversity and avoiding inbreeding. Typically this is accomplished by minimizing population mean kinship; however, this approach becomes less effective when errors in the pedigree exist and may result in inbreeding depression, or reduced survival. Here, both pedigree- and DNA-based methods were used to assess inbreeding depression in the critically endangered Attwater’s prairie-chicken (Tympanuchus cupido attwateri). Less variation in the pedigree-based inbreeding coefficients and parental relatedness values were observed compared to DNA-based measures suggesting that errors exist in the pedigree. Further, chicks identified with high parental DNA-based relatedness exhibited decreased survival at both 14- and 50-days post-hatch. A similar pattern was observed in later life stages (> 50 days post-hatch) with birds released to the wild; however, the pattern varied depending on the time post-release. While DNA-based inbreeding coefficient was positively correlated with mortality to one month post-release, an opposite pattern was observed at nine months suggesting purging of deleterious alleles. I also investigated whether immunocompetence, or the ability to produce a normal immune response, was correlated with survival; however, no significant correlation was observed suggesting that inbreeding was a more important factor influencing survival. Pairing individuals for breeding by minimizing DNA-based parental relatedness values resulted in a significant increase in chick survival. This study highlights the importance of using DNA-based methods to avoid inbreeding depression when errors exist in the pedigree. digital.library.unt.edu/ark:/67531/metadc699930/
Effects of Sertraline Exposure on Fathead Minnow (Pimephales Promelas) Steroidogenesis
Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is widely used for the treatment of depression and anxiety. Due to the abundant therapeutic use of sertraline, low levels have been detected in municipal wastewater effluents suggesting that aquatic organisms may be exposed. The purpose of this study was to evaluate the steroidogenic effects of sertraline on larval (FHM) and adult female fathead minnows (FFHM), Pimephales promelas. Larval FHM were exposed to 0.1, 1, and 10 µg/L sertraline for 28 days and analyzed via RT-qPCR for differential expression of 11β-Hydroxysteroid dehydrogenase (11β-HSD), 20β-Hydroxysteroid dehydrogenase (20β-HSD), aromatase (CYP19), and nuclear thyroid receptor alpha (TRα). FFHM were exposed to 3 or 10 µg/L sertraline for 7 days with the brain and ovary excised at exposure termination. Juvenile FHM exposed to 0.1 μg/L sertraline had a significant upregulation of both 20β-HSD and TRα. FFHM exposed to 10 µg/L sertraline had a significant upregulation of 11β-HSD expression in brain tissue, while no steroidogenic changes were observed in the FFHM ovary. Similarly, in FFHM brain tissue, CYP19 and 20β-HSD expression levels were significantly higher in fish exposed to 10µg/L sertraline compared to control. The significance of these findings with respect to survival, growth and reproduction are currently unknown, but represent future research needs. digital.library.unt.edu/ark:/67531/metadc700070/
Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses
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The purpose of this study is to find out that if antibiotic streptomycin decreases neuronal network activity or affects the pharmacological responses. The experiments in this study were conducted via MEA (multi-electrode array) technology which records neuronal activity from devices that have multiple small electrodes, serve as neural interfaces connecting neurons to electronic circuitry. The result of this study shows that streptomycin lowered the spike production of neuronal network, and also, sensitization was seen when neuronal network pre-exposed to streptomycin. digital.library.unt.edu/ark:/67531/metadc700026/
Monitoring Monocyte Oxldl Phagocytosis As a Cardiovascular Disease Risk Factor Following a High-fat Meal
Macrophage-derived foam cells play a predominant role in the deposition of arterial plaques during the early stages of atherosclerosis. The deposition of arterial plaques is known to be effected by several factors, including a person’s dietary habits. The consumption of a high-fat (>60% of calories from fat) meal is known to elevate serum LDL and triglycerides, which have been previously implicated in the formation pf foam cells. One limitation of current research models is that it is not possible to directly measure foam cells in vivo. Thus, the purpose of the present study was to validate the use of blood derived monocytes as a proxy measure of foam cells. In order to complete this objective, we evaluated monocyte oxLDL phagocytosis capacity following consumption of a high-fat meal. Eight men and women participated in the present study and venous blood samples were collected prior to the meal, 1-h, 3-h, and 5-h post-meal. Monocytes (CD14+/16- and CD14+/16+) were evaluated for adhesion molecule expression (CD11a, CD11b, and CD18), scavenger R (CD36) expression, and oxLDL phagocytosis using an image-based flow cytometry method developed in our laboratory for this purpose. Data was statistically analyzed for significance using a single-factor ANOVA with repeated measures and a p < 0.05. Consumption of a high-fat meal caused an increase significant increase in the proportion of pro-inflammatory monocytes (CD14+/16+) and a decrease in classic monocytes (CD14+/16-), with the greatest difference occurring at 5 h post prandial (p = 0.038). We also found that pro-inflammatory monocyte expression of adhesion molecules and CD36 increased in a manner that would promote in vivo movement of monocytes into the subendothelial space. Finally, over the course of the 5 h postprandial period, the majority of oxLDL uptake occurred in pro-inflammatory compared to classic monocytes. These results suggest that consuming a high-fat meal increases the potential of monocytes to become foam cells for at least 5 h postprandial. digital.library.unt.edu/ark:/67531/metadc700101/
Microflora in Prepared Foods Dispensed from Eating Establishments in Dallas, Texas
A bacteriological study was made of a number of prepared foods that were bought ready-to-eat, for home consumption, from several food establishments in Dallas, Texas. The purpose of this study was to show whether these foods could be a potential source of food poisoning; whether there are any particular foods that should have greater care than others in order to protect their quality; and whether the bacteriological contamination could have been prevented by strict observance of the city regulations for handling foods. digital.library.unt.edu/ark:/67531/metadc699670/
A Study of Selected Factors Influencing Science Majors Toward Science Careers
"The purpose of this study is to gather information concerning some factors which may have operated to influence science majors in North Texas State College toward science careers."--4. digital.library.unt.edu/ark:/67531/metadc699495/
The Effects of Common Electrolytes on Growth and Development of Selected Species of Aquatic Actinomycetes
The role that aquatic actinomycetes play, in the production of tastes and odors in water supplies has been investigated since 1948. The ability of these organisms to produce by-products in lakes and streams, which renders the water unpalatable, is of considerable public health importance. It is desirable that the waterworks industry has as much information as possible concerning the factors that contribute to the growth of these organisms. Since it appears that the aquatic actinomycetes may be isolated from most fresh-water sources, the problem of diversified environments and nutritional requirements offers an excellent field of investigation. The fresh-waters of the world contain variable quantities of electrolytes that may determine in part the biological activity of these organisms. The unsolved questions in this instance are concerned with the electrolytes present and their quantitative effects on the growth and development of these forms. digital.library.unt.edu/ark:/67531/metadc699578/
A Study of a Selected Group of Science Related Characteristics of Non-Science Majors
The purpose of this study is to gather information related to the characteristics of two groups of undergraduate non-science majors; namely, those students who once considered science as a career and subsequently changed to a non-science major and those who have never considered a career in science. It is frequently observed that children in the elementary school have an intense interest in science. One of the principal concerns of this study is how and for what reasons has the interest in science changed between elementary school and college? It is also the purpose of this study to gather information related to the attitudes of these college students toward the science courses they have had in high school and toward their science teachers. In attempting to arrive at an answer, the group who once considered a science career and those who have never considered an occupational choice in a field of science will be compared in the following areas: 1. General information such as sex, age, size of high school attended, rank within their graduating classes, college classification and military experiences. 2. Occupations and hobbies of parents. 3. Experiences which may influence attitudes toward science such as elementary school science, high school science courses, high school science teachers, attitudes toward science requirements, high school courses liked most, high school courses liked least, and membership in science clubs. 4. College science courses completed. 5. Extent of the interviewees' present interest in science, Finally, the circumstances surrounding the tentative choice of a science career by those who once considered such a career will be discussed. digital.library.unt.edu/ark:/67531/metadc699385/
Bacteriological Studies of the Campus Drinking Fountains of North Texas State Teachers College Denton, Texas
"In order to gain an adequate idea of the sanitary condition of the drinking fountains on the North Texas State Teachers College campus, it was found necessary to approach these bacteriological studies from a seasonal point of view."--1. digital.library.unt.edu/ark:/67531/metadc699574/
A Vegetative Key to the Grasses of Erath County, Texas
"The orientation of this study began with a collection of the grasses of Erath County during their flowering periods. Collections were made in the Spring and Fall of 1950 and 1951 to obtain both vernal and autumnal grasses. Identifications were made from the grass floras previously mentioned and checked against specimens in the herbarium of North Texas State College for verification. In addition, the list was checked by W.A. Turney, Conservationist, United States Department of Agriculture of Dublin, Texas. Finally, the list was compared with that prepared by W.M. Cory for the plant areas of which Erath County is a part. On the basis of the above identifications, a critical study of the vegetative characteristics was made and a key based on these features prepared. The width of the blad and characteristics of the ligule, roots, culms, and sheaths were used to distinguish each of the eighty-six specimens found in the collection area. A drawing was made of the longitudinal section of the juncture of the blade and the sheath of each grass. This diagnostic section includes the collar, ligule, a part of the blade and sheath, and auricles, if present."-- leaf 5. digital.library.unt.edu/ark:/67531/metadc663288/
An Investigation of Naturally Occurring Tastes and Odors from Fresh Waters
The Problem of the cause and control of tastes and odors in water supplies has been the subject of a great many investigations during the last half-century; however, many questions in this field remain to be answered. Theories relating to the cause of tastes and odors occurring in water are still rather numerous and, at present, only a few of them are compatible. Although several procedures have been employed for the eradication of tastes and odors from water supplies, none of them are completely successful. digital.library.unt.edu/ark:/67531/metadc663624/
Biogeographic Relationships of Pocket Gophers (Geomys breviceps and Geomys bursarius) in the Southeastern Portion of Their Ranges
This research utilized population genetic analyses (protein starch-gel electrophoresis and DNA sequencing of the cytochrome b mtDNA gene), host-parasite specificity (lice coevolution), remote sensing of satellite data, and geographic information systems (GIS) to characterize newly discovered populations of pocket gophers (genus: Geomys) in Arkansas. These populations are isolated and occur in seemingly unsuitable habitat in the Ozark Mountains of Arkansas. Analyses of electrophoretic and ectoparasite data suggested the populations in the Ozark Mountains represented isolates allied to Geomys bursarius, a species not known to occur in Arkansas. Comparison of mitochondrial DNA sequence data of the cytochrome b gene with that of other taxa and morphometric analyses confirmed that these populations are most closely allied to G. bursarius occurring to the north in Missouri. Moreover, these mtDNA sequence analyses indicated a degree of differentiation typical of that between other subspecies of pocket gophers. Therefore, these populations represent a distinct genetic entity in an intermediate stage of speciation and should be designated as a new subspecies, Geomys bursarius ozarkensis. Molecular clock analysis revealed a time of lineage divergence for this new subspecies as approximately 511,000 YBP. Due to the isolated nature and limited distribution of this subspecies, an evaluation of critical habitat needs was initiated. Remote sensing and GIS technologies were used to identify and describe suitable habitat Computerized classification of satellite imagery of suitable vegetation, integrated with ancillary digital information on soil associations, roads, and water systems, revealed that human activity had played a positive role in the establishment and dispersal of pocket gophers in this area. This research represents an initial combination of classical systematic tools with remote sensing and GIS to investigate biogeographic patterns and evolution. This project establishes a framework for using an interdisciplinary approach to studying organisms with limited distributions, determining evolutionary status, and providing recommendations for conservation. digital.library.unt.edu/ark:/67531/metadc500612/
Dalbergia and Albizia: Plantlet Production via Tissue Culture, Karyological Evaluation, and Seed Anatomy with Scanning Electron Microscopy
A publication by the National Academy of Sciences, USA (1979) outlined some of the research need for a great variety of economically important woody species whose remaining genetic resources need urgently to be collected and conserved. A viable regeneration system was established via tissue and cell suspension culture for Albizia falcataria and A. lebbeck, two important wood yielding leguminous tree species. The culture medium was standardized after several trials to obtain callus from the leaflet explants of these two tree species. The optimum use of casein hydrolysate (w/v) and coconut milk (v/v) in addition to 6-Benzylaminopurine and Indole-3-butyric acid could induce morphogenesis and somatic embryogenesis in the cultured tissue. This reports the first observation on somatic embryogenesis ofA. lebbeck using leaflets as the explants. Scanning Electron Microscopy and histological studies were done on the different stages plant development following standard techniques. Embryogenesis in suspension culture followed regeneration of plantlets in A. lebbeck. In A.falcaaria the regenerative process followed via organogenesis from the shoot buds developed on the leaf explants. After hardening the regenerated plants were transferred to the greenhouse. Some of the trees grew more than 25 feet tall within a few months outside the greenhouse. Karyotype of the three leguminous trees Albizia lebbeck, A. falcataria, and Dalbergia sissoo was analyzed. In D. sissoo, various chromosomal anomalies were observed in the cultured tissue. The abnormality indices and ploidy level varied with the age and the frequency of the subculture. In the aged culture the regenerative potential declined but was reinstated to some extent with the addition of two complex growth factors, coconut milk and casein hydrolysate. Seed anatomy of 26 species of 4 leguminous genera was studied with SEM. The main distinguishing anatomical features observed in the seed sections were uniseriate or multiseriate epidermis, epidermal projections, and number of rows and nature of columns of hypodermal layer, especially the nature of endosperm. Three species of Dalbergia, Acacia and Cassia and two species of Albizia are difficult to distinguish externally even with seed coat study under SEM, but this study with cross sections provided enough characteristic features to distinguish one from the other. digital.library.unt.edu/ark:/67531/metadc500610/
Remote Sensing of Landscape-Level Ecological Attributes at Ray Roberts Lake in North Texas
Biological diversity is a key component in assessing ecosystem health. Alteration, degradation and loss of habitat due to human influence is currently the primary stressor resulting in decreases in diversity. Reliable assessment of large areas in terms of biological integrity are needed for conservation and preservation efforts. Remotely sensed data provide an integrated view of reflected electromagnetic energy over large areas of the earth. These energy patterns provide unique spectral signatures which can be correlated to land cover and habitat. This research sought relationships between traditional ecological measures and information gathered from satellite digital imagery. Reliable interpretation of earth surface characteristics relies largely on accurate rectification to a map projection and subsequent thematic classification. Use of the Global Positioning System (GPS) for rectification was superior than digitizing topographical maps. Differentially corrected GPS locations provided optimum rectification with SPOT satellite imagery while marginally better rectifications were obtained for Landsat MSS imagery using uncorrected GPS positions. SPOT imagery provided more accurate land cover classifications than did MSS. Detection of temporal land cover change using MSS imagery was hampered by confusion among intermediate successional classes. Confusion between upland and bottomland forest classes occurred with both SPOT and MSS. Landscape analyses using thematic maps produced from the previously discussed endeavors suggested that terrestrial habitat in the Ray Roberts Lake area became more fragmented and complex in shape. Habitat patches became smaller but more numerous. Forested areas were most effected and conservation efforts should focus on management strategies that promote vegetation succession and forest maturation. Remotely sensed SPOT data were successfully used to predict tree basal area. There were no significant relationships found with other in situ measures or between MSS data and any vegetation measures. Remote sensing provided information suitable for large scale projects concerning landscape-level ecological issues. Rectification and classification accuracies were the primary factors influencing meaningful interpretation. Project goals should determine the scale of remotely sensed data and acceptable level of accuracy. digital.library.unt.edu/ark:/67531/metadc500958/
Role of α-Keto Acids In Cyanide Detoxification and Assimilation by Pseudomonas Bacteria
Cyanide was rapidly removed when added to culture supernatants of seven different Pseudomonas. The ability to remove cyanide was correlated with the accumulation of α-keto acids (pyruvate and α-ketoglutarate). These compounds react with cyanide forming less toxic cyanohydrins, thus conferring a mechanism for bacterial cyanide tolerance. When added to growth media the α-keto acids were shown also to serve as effective cyanide antagonists. While all bacteria tested accumulated α-keto acids, only those capable of utilizing cyanide as a nutritional nitrogen source were able to metabolize cyanohydrins. In P. fluorescens NCIMB 11764, the same enzyme (cyanide oxygenase) shown previously to be involved in cyanide metabolism appears responsible for cyanohydrin transformation. Keto acid excretion is believed to represent a new mechanism of bacterial cyanide detoxification with further enzymatic metabolism of the cyanohydrins helping to explain how cyanide can satisfy the nitrogen requirement in cyanide-utilizing bacteria. digital.library.unt.edu/ark:/67531/metadc500761/
Distribution of a Novel Gram Negative, Capsule-Forming Bacterium
A novel Gram negative, capsule-forming bacterium was previously isolated in Dr. G. Roland Vela's laboratory. The distribution of this bacterium in soils from various locations was investigated. Soil samples from 188 locations around the world were examined. Isolates of the bacterium were obtained from 50 of these soils, with 48 of the isolates found in soils from the southwestern United States and northern Mexico. This suggests that this region is the natural habitat of the bacterium. The other two isolates were obtained from Madrid, Spain and Taipei, Taiwan. None were found in soils from South America or Australia. A lack of variation in morphology and physiological properties in the isolates suggests that a homogeneous population exists, even from widespread geographical locations. digital.library.unt.edu/ark:/67531/metadc500729/
Development of an In Vitro Protoplast Culture System for Albizia Lebek (L.) Benth., an Economically Important Leguminous Tree
An in vitro system of generating protoplasts from their callus cultures was established. The friable callus was more productive in terms of producing protoplasts than the green compact callus. The concentration of the various cell wall degrading enzymes had an effect on the viability of the protoplasts in the medium. The protoplast system developed from the experiments was stable and could be used for the transformation experiments of Albizia lebek and for other plant improvement practices. digital.library.unt.edu/ark:/67531/metadc500422/
Biodiversity of Dragonflies and Damselflies (Odonata) of the South-Central Nearctic and Adjacent Neotropical Biotic Provinces
The south-central United States serves as an important biogeographical link and dispersal corridor between Nearctic and Neotropical elements of western hemisphere odonate faunas. Its species are reasonably well known because of substantial collections, but there has been no concerted effort to document the extent of biodiversity and possible geographic affinities of dragonflies and damselflies of this region. The recent discoveries of Argia leonorae Garrison, Gomphus gonzalezi Dunkle and Erpetogomphus heterodon Garrison from southern and western Texas and northern Mexico suggest that Odonata species remain to be discovered in this area, particularly from far south Texas and northern Mexico. I have documented a total of 12,515 records of Odonata found in 408 counties within the south-central U.S. A total of 73 species of damselflies and 160 species of dragonflies was revealed in the region. The 233 (197 in Texas) Odonata species are distributed among 10 families and 66 genera. Illustrated family, generic, and species-level keys are provided. Since the beginning of this work in the Fall of 1993, one species has been added each to the Louisiana and Oklahoma faunas, and 12 species have been added, previously unreported from Texas, including four new to the U.S. The area of highest Odonata biodiversity overall (161 spp.) is in the Austroriparian biotic province. The greatest degree of faunal similarity between the south-central U.S. and other intra-continental regions was observed for the eastern (64%) United States. Diversity is a function of area, and as expected, the numbers of breeding birds and Odonata, in each contiguous U.S. state are positively correlated (r=0.376, n=33, p=0.031). There is, however, no strong correlation between land area and species diversity within the region, but those natural biotic provinces (Austroriparian, Texan, Balconian) where aquatic systems and topographic heterogeneity are the greatest provide a broader spectrum of potential Odonata habitats and thus support a greater number of Odonata species. digital.library.unt.edu/ark:/67531/metadc501251/
Isolation and Characterization of a New Capsule-Forming Bacterium
A unique, previously undescribed Gram-negative bacterium was isolated from several soils in Texas and extensively characterized in this study. The cells measured 1-2 by 4-6 μm. The distinguishing characteristic of the bacterium is the extraordinary capsular material which surrounds the cells. The new isolates are aerobic, mesophilic, non motile and have the ability to utilize a variety of organic compounds as the sole source of carbon and energy. The organism grows optimally at 30° C and the optimal pH lies between 7.0-8.0. The isolates produce catalase but oxidase is not produced. They do not produce indole or hydrogen sulfide. The organism can hydrolyze gelatin and Tween 80 but not starch, esculin and casein. The major cellular fatty acid is anteiso 15:0. The guanine and cytosine content is 58-62 mole%. The organism's taxonomic position was further established by specific gene probes, 16S rRNA homology, DNA homology and "ribotyping." These data showed that it was most closely related to members of the genus Paenibacillus, although somewhat divergent from other species classified in this genus. After careful evaluation of the results obtained during this study, it is proposed that this unique bacterium be named Paenibacillus velasolus sp. nov. digital.library.unt.edu/ark:/67531/metadc500460/
A Multimedia Atlas of Dissection for Comparative Anatomy of the Vertebrates
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This interactive multimedia content is part of the thesis that was prepared for the degree of Master of Science in Biology: http://digital.library.unt.edu/ark:/67531/metadc2224. Traditional methods of teaching the laboratory course for Comparative Anatomy of the Vertebrates could be improved by applying current computer technology to construct an interactive, multimedial atlas of dissection. Five specimens used in comparative anatomy courses at most institutions were chosen as representative members of the Phylum Chordata: amphioxus, lamprey, dogfish shark, mud puppy, and cat. Specimens were dissected according to the modified method of Wischnitzer, 1993, and each stage was photographed with a Kodak DC120 digital zoom camera. These images were processed on a Power Macintosh 7600 computer with Adobe Photoshop v. 5.0. The atlas was constructed from these images using Macromedia Authorware v. 4.0.3. Each image contains a series of interactive objects that display a highlight and descriptive text as the cursor passes over each object. digital.library.unt.edu/ark:/67531/metadc500425/
Developing a Collection Digitization Workflow for the Elm Fork Natural Heritage Museum
Natural history collections house immense amounts of data, but the majority of data is only accessible by locating the collection label, which is usually attached to the physical specimen. This method of data retrieval is time consuming and can be very damaging to fragile specimens. Digitizing the collections is the one way to reduce the time and potential damage related to finding the collection objects. The Elm Fork Natural Heritage Museum is a natural history museum located at the University of North Texas and contains collections of both vertebrate and invertebrate taxa, as well as plants. This project designed a collection digitization workflow for Elm Fork by working through digitizing the Benjamin B. Harris Herbarium. The collection was cataloged in Specify 6, a database program designed for natural history collection management. By working through one of the museum’s collections, the project was able to identify and address challenges related to digitizing the museum’s holdings in order to create robust workflows. The project also produced a series of documents explaining common processes in Specify and a data management plan. digital.library.unt.edu/ark:/67531/metadc500042/
Immunohistochemistry of the Gills of the Channel Catfish Ictalurus Punctatus: Cells and Neurochemicals That May Be Involved in the Control of Cardioventilatory Reflexes
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In teleost fishes the neurochemicals involved in sensing and responding to hypoxia are unresolved. Serotonergic branchial neuroepithelial cells (NECs) are putative O2 chemoreceptors believed to be homologous to the neural crest (NC) derived APUD (amine-precursor uptake and decarboxylation) pulmonary NECs and carotid body type-1 glomus cells. Branchial NECs contain serotonin (5-HT), thought to be central to the induction of the hypoxic cardioventilatory reflexes. However, application of 5-HT in vivo does not elicit cardioventilatory reflexes similar to those elicited by hypoxia. But previous in vitro neural recordings from glossopharyngeal (IX) afferents innervating O2 chemoreceptors in the trout gill show the same discharge response to hypoxic conditions as does that of acetylcholine (ACh) application. This evidence strongly supports the cholinergic hypothesis of chemoreceptor impulse origin rather than a serotonergic-induced impulse origin model. We therefore hypothesized that NECs contain ACh among other neurochemicals in cells belonging to the APUD series. Although serotonergic branchial NECs did not colocalize with ACh using immunohistochemical methods, several populations of ACh and/or tyrosine hydroxylase (TH) (catecholaminergic) positive, dopamine (DA) negative, cells were found throughout the second gill arch of the channel catfish Ictalurus punctatus. In addition, the NC derivation marker zn-12 labelled the HNK-1-like epitope (Human natural killer) expressed by lamellar pillar cells’ collagen column-associated pillar cell adhesion molecules (CC-PCAMs), evidence confirming their hypothesized NC origin. digital.library.unt.edu/ark:/67531/metadc407757/
Shortened in Vivo Bioconcentration Factor Testing in Cyprinus Carpio
Bioconcentration factor testing serves as the most valuable surrogate for the assessment of bioaccumulation. The assessment of potentially harmful chemicals is crucial to not only the health of aquatic environments, but to humans as well. Chemicals that possess the ability to persist in the environment or that have the potential to bioaccumulate, pose a greater risk to organisms that are exposed to these chemicals. The Organization for Economic Cooperation and Development Guideline 305 outlines specific protocols to run an accurate and reliable aquatic flow-through test. However, since its adoption in 1996, very few changes have been made to accommodate the endeavor to lowering the amount of test species to run one of these said tests. Running an aquatic flow-through test, according to 305, takes much time and money as well as numerous amounts of fish. Such burdens can be eliminated through simple modifications to the standard protocols. In this study, we propose an abbreviated study design for aquatic bioconcentration testing which effectively alleviates the burdens of running a flow-through test. Four chemicals were used individually to evaluate the usefulness of the proposed shortened design; 4-Nonyphenol, Chlorpyrifos, Musk Xylene, and DDT. The study consisted of exposing Cyprinus carpio for 7 days followed by 7 days of depuration, for a total of a 14-day study. Our results for each of the four compounds are consistent with literature values, thus, demonstrating that BCFk can be accurately predicted in an abbreviated in vivo test. digital.library.unt.edu/ark:/67531/metadc407781/
The Effect of Menthol on Nicotine Metabolism: a Cross Species Evaluation
The effect of menthol on nicotine metabolism was examined in liver S9 fractions of four different species and in the in vivo mouse model. The purpose of this study was to investigate three parameters: (1) biotransformation of nicotine to cotinine in various species (human, mouse, rat and trout) using in vitro methods; (2) to determine if the addition of menthol with nicotine altered biotransformation of nicotine to cotinine; (3) and to assess similar parameters in an in vivo mouse model. The major findings of this study include: (1) mice appear to metabolize nicotine, over time, in a manner similar to humans; (2) menthol decreased cotinine production, over time, after a single dose in mice; and (3) menthol increased cotinine production, over time, after repeated doses, in mice. digital.library.unt.edu/ark:/67531/metadc407773/
Relationships of Benthic Macroinvertebrate Community Structure with Land-use, Habitat, In-stream Water Chemistry, Depositional Sediment Biofilm Fatty Acids, and Surfactants in the Effluent Dominated Texas Trinity River
The Trinity River is an urbanized, effluent-dominated river, and is heavily relied upon for drinking water. The benthic macroinvertebrate community has been monitored for over 20 years, with the focus of this dissertation on three studies (1987-88, 2005, and 2011). Water quality improvement following dechlorination resulted in increased benthic metrics. Overall habitat quality, in-stream cover, surface water total organic carbon, sediment total organic carbon, near-field urban land-use, near-field forested land-use, surface water surfactant toxic units, and depositional sediment biofilm fatty acids all have statistically significant relationships with benthic macroinvertebrate metrics. These relationships are better defined with increased taxonomic resolution at the genus/species level for all benthic taxa, including Chironomidae and Oligochaeta. It is recommend that benthic identifications for state and city water quality assessments be done at the genus/species level. A novel method for quantifying depositional sediment biofilm fatty acids has been produced and tested in this dissertation. Benthic metrics are directly related to fatty acid profiles, with several essential fatty acids found only at upstream sites. digital.library.unt.edu/ark:/67531/metadc407738/
Effects of Airway Pressure, Hypercapnia, and Hypoxia on Pulmonary Vagal Afferents in the Alligator (Alligator Misssissippiensis)
The American alligator (Alligator mississippiensis) is an aquatic diving reptile with a periodic breathing pattern. Previous work has identified pulmonary stretch receptors (PSR), both rapidly- and slowly-adapting, and intrapulmonary chemoreceptors (IPCs) that modulate breathing patterns in alligators. The purpose of the present study was to identify the effects of prolonged lung inflation and deflation (simulated dives) on PSR and/or IPC firing characteristics in the alligator. The effects of airway pressure, hypercapnia, and hypoxia on dynamic and static responses of pulmonary stretch receptors (PSR) were studied in juvenile alligators (mean mass = 246 g) at 24°C. Receptor activity appeared to be a mixture of slowly-adapting PSRs (SARs) and rapidly-adapting PSRs (RARs) with varying thresholds and degrees of adaptation, but no CO2 sensitivity. Dives were simulated in order to character receptor activity before, during, and after prolonged periods of lung inflation and deflation. Some stretch receptors showed a change in dynamic response, exhibiting inhibition for several breaths after 1 min of lung inflation, but were unaffected by prolonged deflation. For SAR, the post-dive inhibition was inhibited by CO2 and hypoxia alone. These airway stretch receptors may be involved in recovery of breathing patterns and lung volume during pre- and post-diving behavior and apneic periods in diving reptiles. These results suggest that inhibition of PSR firing following prolonged inflation may promote post-dive ventilation in alligators. digital.library.unt.edu/ark:/67531/metadc407750/
Phototoxic Effects of Titanium Dioxide Nanoparticles on Daphnia Magna
Titanium dioxide nanoparticles (TiO2-NP) are one of the most abundantly utilized nanomaterials in the world. Studies have demonstrated the mechanism of acute toxicity in TiO2-NP to be the production of reactive oxygen species (ROS) leading to oxidative stress and mortality in exposed organisms. It has also been demonstrated that the anatase crystalline conformation is capable of catalyzing the cleavage of water molecules to further increase the concentration of ROS in the presence of ultraviolet radiation. This photoenhanced toxicity significantly lowers the toxicity threshold of TiO2-NP to environmentally relevant concentrations (ppb). The goal of this study was to determine whether dietary uptake and accumulation of TiO2-NP in the aquatic filter feeder Daphnia magna resulted in photoenhanced toxicity. D. magna and S. caprincornatum were exposed to aqueous solutions of 20ppm and 200ppm TiO2-NP for 24hrs and then transferred to clean moderately hard water. Samples were taken at various time points, dried, and TiO2 quantified using ICP-MS. Toxicity assays were run on D. magna using three TiO2-NP (20ppm, 200ppm) exposure protocols and two ultraviolet radiation treatments. The first exposure group was exposed to aqueous solutions of TiO2-NP for the duration of the test. The second exposure group was exposed to TiO2-NP for an hour and then transferred to clean water. The third exposure group was fed S. capricornatum that had been allowed to adsorb TiO2-NP. All samples were then placed in an outdoor UV exposure system and exposed to either full spectrum sunlight (with UV) or filtered sunlight (no UV). Here we show that TiO2 uptake peaked at one hour of exposure likely due to sedimentation of the particles out of suspension, thus decreasing bioavailability for the duration of the test. Interetsingly, when D. magna were moved to clean water, aqueous concentrations of TiO2 increase as a result of depuration from the gut tract. Data also suggests these excreted particles were bioavailable and re-consumed by D. magna. These data will contribute to the understanding of TiO2-NP environmental fate and toxicity. digital.library.unt.edu/ark:/67531/metadc407741/
Field and Laboratory Fish Tissue Accumulation of Carbamazepine and Amiodarone
The goals of this dissertation work were to assess the bioaccumulation potential of carbamazepine and amiodarone, two widely used ionizable pharmaceutical compounds that possess mid-range and high LogD values, respectively, and to evaluate alternative methods to assess chemical accumulation in bluntnose minnows, catfish, and tilapia. Results indicated that carbamazepine does not appreciably bioaccumulate in fish tissue with BCFk and BAF carbamazepine values < 10. Amiodarone, however, with a log D of 5.87 at pH 7.4, accumulated in fish tissues with kinetic BCF values <2,400. Collectively, the data suggest that full and abbreviated laboratory-derived BCFs, BCFMs derived from S9 loss-of-parent assays, as well as field BAF values are similar for each of the two drugs. In summary, the results from this dissertation indicated: 1) The reduced design BCF test is a good estimate for the traditional OECD 305 test. 2) In vitro S9 metabolism assays provide comparable BCF estimates to the OECD 305 test. 3) Metabolism may play a large role in the accumulation of drugs in fish. 4) Reduced BCF tests and in vitro assays are cost effective and can reduce vertebrate testing. digital.library.unt.edu/ark:/67531/metadc407838/
The Stoneflies (Plecoptera) of the Ozark and Ouachita Mountains
Collections of stoneflies (Plecoptera) were made at 603 stream sites from Nov. 1983 - May 1988 in the Ozark-Ouachita Mountain region, in relation to physiographic and vegetational characteristics. Examination of approximately 9000 vials from these collections, supplemented with material from major museums and other collectors, revealed 88 stonefly species in 8 families and 24 genera. Pearson's measure of association (R) showed there was a significant association between species present and each of the tested variables. digital.library.unt.edu/ark:/67531/metadc331637/
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