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UNT Theses and Dissertations
- 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 . digital.library.unt.edu/ark:/67531/metadc149643/
- 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. digital.library.unt.edu/ark:/67531/metadc149693/
- Detection of Mercury Among Avian Trophic Levels at Caddo Lake and Lake Lewisville, TX
- Mercury (Hg) is a globally distributed toxicant that has been shown to have negative effects on birds. in the United States, avian taxa have been shown to possess high Hg concentrations in the northeast, Great Lakes and Everglades ecosystems; however, few studies have measured avian Hg concentrations in other geographic regions. Previous studies have documented high Hg concentrations in multiple organisms in east Texas, but birds were not included in these studies. the main objective of the present study was to quantify Hg concentrations in birds in differing trophic levels at Caddo Lake and Lake Lewisville, TX. Results suggest that Hg concentrations may be high enough to negatively impact some bird taxa, particularly those at high trophic levels, residing at both Caddo Lake and Lake Lewisville. digital.library.unt.edu/ark:/67531/metadc115153/
- 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 from seasonal drying and floods. Sustainable use of groundwater resources and conservation of riparian corridors is vital to protecting groundwater-dependent ecosystems that play a vital role in maintaining regional biodiversity by serving as biotic refugia during catastrophic disturbance. digital.library.unt.edu/ark:/67531/metadc115054/
- Examining the Shade/flood Tolerance Tradeoff Hypothesis in Bottomland Herbs Through Field Study and Experimentation
- While there is growing evidence that shade/flood tolerance tradeoffs may be important in distributions of bottomland hardwood trees and indications that they should apply to herbs, no studies have definitively explored this possibility. Four years of field data following historic flooding were supplemented with a greenhouse experiment designed to identify interactions congruent with tradeoffs. Fifteen bottomland species were grown in two levels of water availability and three levels of shade over 10 weeks. Results indicate responses of Fimbristylis vahlii and Ammannia robusta are consistent with tradeoffs. Modification of classical allometric responses to shade by substrate saturation indicates a potential mechanism for the tradeoff in A. robusta. Responses indicating potential for increased susceptibility to physical flooding disturbance are also discussed. digital.library.unt.edu/ark:/67531/metadc115161/
- 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. digital.library.unt.edu/ark:/67531/metadc115137/
- 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. digital.library.unt.edu/ark:/67531/metadc103303/
- 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. digital.library.unt.edu/ark:/67531/metadc103372/
- 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. digital.library.unt.edu/ark:/67531/metadc84278/
- 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. digital.library.unt.edu/ark:/67531/metadc67974/
- 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. digital.library.unt.edu/ark:/67531/metadc68035/
- 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‐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. digital.library.unt.edu/ark:/67531/metadc67956/
- 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. digital.library.unt.edu/ark:/67531/metadc67953/
- Determination of Bioconcentration Potential of Selected Pharmaceuticals in Fathead Minnow, Pimephales Promelas, and Channel Catfish, Lctalurus Punctatus
- The primary objective of this work was to determine the tissue-specific bioconcentration factors (BCFs) of the selected pharmaceuticals: norethindrone (NET), ibuprofen (IBU), verapamil (VER), clozapine (CLZ) and fenofibrate (FFB) in two freshwater fishes: fathead minnow and channel catfish. BCF tests on fathead followed the standard OECD 42-day test while a 14-day abridged test design was used in catfish exposures. Additional objectives included a) comparing the measured BCFs to the US EPA's BCFWIN model predicted values, b) comparing the BCF results from the standard and reduced tests, and c) prediction of chronic risk of the pharmaceuticals in fish using the human therapeutic plasma concentrations. Each test included uptake and depuration phases to measure tissue-specific kinetic BCFs. The results indicated that all the pharmaceuticals, except IBU, have the potential for accumulation in fish. Estimated BCFs for NET, VER and FFB may not be significant in view of the current regulatory trigger level (BCF ≥ 2000); however, CLZ's BCF in the liver had approached the criterion level. Significant differences were noticed in the tissue-specific uptake levels of the pharmaceuticals with the following general trend: (liver/kidney) > (gill/brain) > (heart/muscle) > plasma. IBU uptake was highest in the plasma. When compared to the measured BCFs, predicted values for NET, IBU, VER and FFB were slightly overestimated but did not differ largely. However, the measured BCF of CLZ in the liver was approximately two-orders of magnitude higher than the predicted level. The tissue-BCFs for the two species were not widely different indicating the potential usefulness of the reduced BCF test. Comparison of fish and human plasma levels indicated that NET, CLZ and VER have the potential to cause chronic effects in fish. digital.library.unt.edu/ark:/67531/metadc33189/
- Endocannabinoid System in a Planarian Model
- In this study, the presence and possible function of endocannabinoid ligands in the planarian is investigated. The endocannabinoids ananadamide (AEA) and 2-arachidonoylglycerol (2-AG) and entourage NAE compounds palmitoylethanolamide (PEA), stearoylethanolamide (SEA) and oleoylethanolamide (OEA) were found in Dugesia dorotocephala. Changes in SEA, PEA, and AEA levels were observed over the initial twelve hours of active regeneration. Exogenously applied AEA, 2-AG and their catabolic inhibition effected biphasic changes in locomotor velocity, analogous to those observed in murines. The genome of a close relative, Schmidtea mediterranea, courtesy of the University of Utah S. med genome database, was explored for cannabinoid receptors, none were found. A putative fatty acid amide hydrolase (FAAH) homolog was found in Schmidtea mediterranea. digital.library.unt.edu/ark:/67531/metadc33188/
- Induced Bradycardia Effects on Angiogenesis, Growth and Development in Early Development in Chicken Embryos, Gallus Domesticus
- Cardiac performance, angiogenesis and growth was investigated during early chicken development. Heart rate, and thus arterial pulse pressure and cardiac output, were altered with the bradycardic drug ZD7288. Heart rates at 72 h of development of control embryos and those dosed with chicken Ringer were not different at 171 bpm. Acute and chronic application of ZD7288 caused significant bradycardia. Chronic dosing of Ringer and ZD7288 changed neither eye diameter nor development rate. Chronic dosing of ZD7288 did not significantly alter CAM vessel density close to the embryo (2, 3 and 4 mm) but at farther distances (5 and 6 mm) chronic dosing with both Ringer and ZD7288 decreased vessel density by 13 - 16%. Chronic dosing with ZD7288 also reduced body mass by 20%. Thus, lowered heart rate and cardiac output had little effect on vessel density or developmental stage, but did reduce embryo growth. digital.library.unt.edu/ark:/67531/metadc33199/
- 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. digital.library.unt.edu/ark:/67531/metadc67941/
- Thermal Identification of Clandestine Burials: A Signature Analysis and Image Classification Approach
- Clandestine burials, the interred human remains of forensic interest, are generally small features located in isolated environments. Typical ground searches can be both time-consuming and dangerous. Thermal remote sensing has been recognized for some time as a possible search strategy for such burials that are in relatively open areas; however, there is a paucity of published research with respect to this application. This project involved image manipulation, the analyses of signatures for "graves" of various depths when compared to an undisturbed background, and the use of image classification techniques to tease out these features. This research demonstrates a relationship between the depth of burial disturbance and the resultant signature. Further, image classification techniques, especially object-oriented algorithms, can be successfully applied to single band thermal imagery. These findings may ultimately decrease burial search times for law enforcement and increase the likelihood of locating clandestine graves. digital.library.unt.edu/ark:/67531/metadc33201/
- Functional Neural Toxicity and Endocrine Responses in Mice Following Naphthalene Exposure
- Polycyclic aromatic hydrocarbons (PAHs) are a well studied and diverse class of environmental toxicants. PAHs act via the aryl hydrocarbon receptor (AhR), and studies have suggested that PAHs may elicit neurological and estrogenic effects. Doses of PAHs between 50 to 150 ppm may elicit neurotoxicity in rodent models. The present study investigated the effects of naphthalene on in vivo steroidogenesis in Swiss Webster male mice, and in vitro neural function of Balb-C/ICR mice frontal cortex neurons. These data suggest that naphthalene may not elicit steroidogenic effects at concentrations ranging from 0.2 to 25 mg/kg/day, following a 7 day subcutaneous dosing regime. In addition, naphthalene may cause functional toxicity of frontal cortex neurons at concentrations of 32 to 160 ppm naphthalene. digital.library.unt.edu/ark:/67531/metadc31529/
- The Influence of in Vitro Gill and Liver Metabolism of Xenobiotics on Fish Bioconcentration
- This dissertation examines the ability of in vitro biotransformation assays to provide an indication of metabolic potential. The potential for xenobiotic compounds to bioconcentrate in aquatic organisms is expressed through the bioconcentration factor (BCF). The metabolic loss of ibuprofen, norethindrone and propranolol was measured using rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) gill and liver S9 fractions, microsomes and cell suspensions. Metabolic transformation rates (kM) were extrapolated from in vitro intrinsic clearance of parent compound (CLm) and integrated into a refined BCF model. In general, CLm of test compounds was greater in liver S9 fractions and hepatocytes. However, the influence of hepatic metabolism on kM and BCF was limited by hepatic blood flow (20-25%) compared to gill blood flow (~100%). A significant difference was noted between BCF solely based on KOW and BCF including kM. These studies indicate that the inclusion of kM in BCF models can bring predicted bioconcentration estimates closer to in vivo values. Primary cell suspensions are preferred over subcellular fractions as cell suspensions possess both phase I and phase II enzyme activity. Further study was conducted on ibuprofen biotransformation pathways. As fish do not contain the same cytochrome P450 (CYP) 2C homologs known to metabolize ibuprofen in mammals, it cannot be assumed that piscine biotransformation is similar. Metabolite analysis found 2-hydroxy-ibuprofen as the major metabolite in S9 and microsomal fractions. Additional assays involving the induction and inhibition of specific CYP isozymes support CYP1A2 as an alternative metabolic pathway. digital.library.unt.edu/ark:/67531/metadc30457/
- Molecular systematics of Baird's pocket gopher (Geomys breviceps)
- Baird's pocket gopher (Geomys breviceps) is found in eastern Texas, eastern Oklahoma, central and western Arkansas, and western Louisiana. The cytochrome-b gene was sequenced and analyzed for 16 pocket gophers from throughout the range of the species. Similar phylogenetic trees were obtained using maximum-parsimony, maximum-likelihood, neighbor-joining, and Bayesian analyses. Two major clades were formed with northern individuals belonging to clade I and southern individuals belonging to clade II. G. b. sagittalis was paraphyletic in relation to G. b. breviceps in all analyses. Based on inconsistencies between the taxonomic classification and systematic relationships within Baird's pocket gopher, a taxonomic restructuring appears warranted. digital.library.unt.edu/ark:/67531/metadc30438/
- Thermal Stress During Pre-Incubation Induces Subsequent Developmental Plasticity in Northern Bobwhites
- Northern bobwhite populations have declined concurrent with global warming. The focal period of this study was the 12-d pre-incubation period, when bobwhite eggs remain in the nest without the thermal protection of the incubating parent. This study first established the storage and thermal limits of bobwhite eggs, then investigated how global warming may impact oviparous embryos and how bobwhite embryos react to acute and chronic doses of simulated drought temperatures during pre-incubation. First, the maximum storage limit of bobwhite eggs was determined by storing eggs ≤21 d and measuring hatching success and pH of egg albumen and yolk. Hatching success of stored eggs declined after 14 d, when yolk and albumen pH reached levels detrimental to embryonic development. Secondly, thermal limits were determined by exposing bobwhite eggs to hyperthermic temperatures (38-52 °C). Bobwhite embryos survived 50 °C for 1 h, 49 °C for 3 h and 46 °C for 6 h. Results indicate an adaptation to the naturally occurring temperature extremes that can occur in the bobwhite's southern range during pre-incubation. Subsequently, bobwhite eggs were exposed to either low constant (LC), low fluctuating (LF), high constant (HC), or high fluctuating (HF) temperatures during pre-incubation to determine if the nature of temperatures differentially affected development. Although eggs exposed to high heat loads (HC and HF), and low heat loads (LF and LC) had equal heating degree-hours within groups, they exhibited differential growth during pre-incubation. Oxygen consumption, hatch timing, and hatching success were also affected by the thermal regimes. Eggs in simulated drought (HF) had a 47% lower hatch rate than eggs in simulated non-drought (LF) indicating that thermal stress during pre-incubation may contribute to population declines during drought. Finally, northern bobwhite eggs were exposed to acute or chronic doses of simulated drought temperatures, which tested for critical periods of development during pre-incubation. Collectively, data indicated that the earliest stages of bobwhite development were more affected by hyperthermic temperatures. Indeed, a critical period of development exists during the first 2/3 of pre-incubation during which exposure to hyperthermic temperatures results in aberrant development, hatching plasticity, and reduced hatch rates. digital.library.unt.edu/ark:/67531/metadc30505/
- Comparison of Heteranthera Dubia (Jacq.) MacM.-associated Macroinvertebrates Between Georgraphical Regions in the United States
- Macroinvertebrates associated with the aquatic plant, water stargrass (Heteranthera dubia), were sampled from 12 waterbodies in four regions of the United States from June to August 2005. Taxa richness, evenness, and diversity were lowest in the Lower Midwest (LMW) region, and higher in Northern sites, especially the Upper Midwest (UMW), and Northeast (NE). While relative abundance varied from site to site and region to region, utilization of the plant by functional groups remained fairly constant. Collector-gatherers consistently comprised the largest portion of invertebrates sampled. The shredder/ herbivore functional group comprised an average of 17 % of total groups. Through an exhaustive literature review, it was found that shredder/ herbivores of water stargrass have not been reported in the literature. Because of this, the herbivore group was analyzed separately and consisted of 2,383 specimens representing 23 species. The most common groups were Rhopalosiphum sp., Nectopsyche spp. and chironomids. No differences were found in herbivore diversity or evenness between sampling regions, but species richness was significantly different. digital.library.unt.edu/ark:/67531/metadc28427/
- Modulation of the Coelomic Fluid Protein Profile in the Earthworm, Lumbricus Terrestris, After Exposure to Copper as Copper Sulfate
- Proteomic techniques were used to analyze the protein profile of earthworm, Lumbricus terrestris, coelomic fluid collected by either whole body dissection method or the coelomic cavity puncture method. Data demonstrated that collection of coelomic fluid using the coelomic cavity puncture method protocol resulted in a 32% reduction, 377 +/- 4.5 vs 253+/- 19.9 (p=0.0007), in the number of individual proteins. It was determined that the coelomic cavity puncture method yielded a "cleaner" preparation, one less contaminated with extraneous proteins from intestinal tissue, gut contents, and body wall materials. This protocol was used in all later studies. The same proteomic techniques were used to evaluate the effects that exposure to Cu (1.0 μg/cm2) as CuSO4 had on the earthworm coelomic fluid profile. Comparison of protein profile from exposed earthworms demonstrated a significant reduction in the number of proteins expressed (184 ± 2.64 vs 253 ±19.9 p=0.0192) when compared to control organisms. Cu exposure also resulted in a modulation of the protein profile with treated earthworms expressing 47 new proteins that were not identified in unexposed worm coelomic fluid. Additionally, 116 proteins found in coelomic fluid collected from normal worms were absent in Cu exposed organisms. Finally, 137 proteins were conserved or found in both control and exposed organisms; however of these proteins, 24 were up-regulated, 105 were down-regulated, and 8 were unchanged as a result of Cu exposure. digital.library.unt.edu/ark:/67531/metadc28428/
- Hypoxic and hyperoxic incubation affects the ductus arteriosus in the developing chicken embryo (Gallus gallus).
- Developing chicken embryos have two ductus arteriosus (DA) that shunt blood away from the lungs and to the chorioallantoic membrane, the embryonic gas exchanger. In mammals, DA closure is stimulated by an increase in blood gas O2 that occurs as the animal begins to breathe with its lungs. The goal of this study was to determine the influence of O2 levels during incubation on the vascular reactivity and morphology of the O2-sensitive DA and to examine the effects of changing O2 levels during late incubation on the morphology of the DA from chicken embryos. In comparison to normoxia, hypoxia (15%) reduced venous O2 levels in day 16 and day 18 embryos and reduced aircell O2 values in day 16, day 18, and internally pipped (IP) embryos, whereas hyperoxia (30%) increased venous O2 levels and aircell O2 level in day 16, day 18, and IP embryos. In comparison to normoxia, hypoxia delayed closure of the DA, whereas hyperoxia accelerated DA closure. In comparison to the left DA from externally pipped (EP) normoxic embryos, the left DA from EP hypoxic embryos exhibited a significantly weaker contractile response to O2. The DA from day 18 hypoxic embryos exhibited a significantly weaker contractile response to norepinephrine and phenylephrine when compared with the DA from day 18 normoxic and hyperoxic embryos. The effect of incubation in hypoxia / hyperoxia during different developmental windows on the DA O2-induced contractile response was observed only in IP embryos that were incubated in normoxia for 16 days and were then moved to hyperoxia. Incubation in hypoxia / hyperoxia resulted in differences in embryo mass, yolk mass, and heart mass. There is an association between the decreased contractile response to O2 and delayed closure in the proximal portion of the DA from hypoxic embryos; as well as an increased contractile response to O2 and accelerated closure in the proximal portion of the DA from hyperoxic embryos. digital.library.unt.edu/ark:/67531/metadc12103/
- In vitro Cultures of Morus alba for Enhancing Production of Phytoestrogens
- Plant estrogens have long been associated with health benefits. The potential of tissue culture techniques for the production of several secondary metabolites has been known for many years. Tissue cultures stimulate the production or induce the biosynthesis of novel compounds not found in the mature plant. Tissue culture of Morus alba, family Moraceae, is known to contain phytoestrogens, was established on plant-hormone supplemented Murashige and Skoog (MS) medium. Petiole and the stem tissue from mature trees were the best explants for initiation and proliferation of calli. The best callus proliferation was obtained on MS medium containing 1-napthalene acetic acid (1mg/ml) and benzylaminopurine (0.5mg/ml) for M. alba. Comparison of phytoestrogens of Moraceae species from in vivo and in vitro tissue isolation were carried out. The estrogenic activities of callus extracts were assayed in an estrogen-responsive yeast system expressing the human estrogen receptor alpha. Male callus extracts had higher estrogenic activity than male and female extracts from in vivo and in vitro tissues. Isolation and characterization of phytoestrogens from above tissues were carried out using solid phase extraction, high perfomance liquid chromatography and mass spectrometry techniques. Biochanin A, an isoflavonoid, was isolated as one of the compounds in male callus extracts. Biochanin A has been known to have an antiestrogenic acitivity in mammals. Isoflavonoid compounds have been characterized as strong protein tyrosine kinase inhibitors in variety of animal cells. Isoflavones are structurally similar to estradiol, and display agonistic and antagonistic interactions with the estrogen receptor. Isoflavones possess therapeutic and preventive properties such as being used for postmenopausal osteoporosis, breast cancer, and inhibition of tumors. digital.library.unt.edu/ark:/67531/metadc12078/
- Investigation of cryopreservation methods for adherent nerve cell networks in vitro.
- Cryopreservation in suspension is commonplace for a variety of cell types. However, cryopreservation of adherent cells has achieved limited success. This research aimed to cryopreserve adherent nerve cell networks in vitro in a manner that preserved network morphology and physiology. Successful implementation would enable long term storage of adherent neuronal networks on microelectrode arrays and on-demand access for use in pharmacological and toxicological testing. Based upon morphological assessments, excellent post-thaw preservation was obtained and post-thaw cultures survived in a transitional medium for up to 3.5 hours. However, transitions to native culture medium post-thaw presented difficulties, ultimately resulting in necrosis. A discussion of methods to supplement the current research and increase post-thaw viability is included in the thesis. digital.library.unt.edu/ark:/67531/metadc12213/
- Metabolic, cardiac and ventilatory regulation in early larvae of the South African clawed frog, Xenopus laevis.
- Early development of O2 chemoreception and hypoxic responses under normoxic (150 mmHg) and chronically hypoxic (110 mmHg) conditions were investigated in Xenopus laevis from hatching to 3 weeks post fertilization. Development, growth, O2 consumption, ventilatory and cardiac performance, and branchial neuroepithelial cells (NEC) density and size were determined. At 3 days post fertilization (dpf), larvae started gill ventilation at a rate of 28 ± 4 beats/min and showed increased frequency to 60 ± 2 beats/min at a PO2 of 30 mmHg. Also at 3 dpf, NECs were identified in the gill filament buds using immunohistochemical methods. Lung ventilation began at 5 dpf and exhibited a 3-fold increase in frequency from normoxia to a PO2 of 30 mmHg. Hypoxic tachycardia developed at 5 dpf, causing an increase of 20 beats/min in heart rate, which led to a 2-fold increase in mass-specific cardiac output at a PO2 of 70 mmHg. At 10 dpf, gill ventilatory sensitivity to hypoxia increased, which was associated with the increase in NEC density, from 15 ± 1 to 29 ± 2 cells/mm of filament at 5 and 10 dpf, respectively. Unlike the elevated rate, cardiac and ventilatory volumes were independent of acute hypoxia. Despite increased cardioventilatory frequency, larvae experienced an average of 80% depression in during acute hypoxia. Chronic hypoxia (PO2 of 110 mmHg) decreased mass-specific cardiac performance before 10 dpf. In older larvae (10 to 21 dpf), chronic hypoxia decreased acute branchial and pulmonary hypoxic hyperventilation and increased NEC size. Collectively, these data suggest that larvae exhibit strong O2-driven acute hypoxic responses post-hatching, yet are still O2 conformers. All acute hypoxic responses developed before 5 dpf, and then the effects of chronic hypoxia started to show between 7 and 21 dpf. Thus, the early formation of acute hypoxic responses is susceptible to the environment and can be shaped by the ambient PO2. digital.library.unt.edu/ark:/67531/metadc12175/
- Cardio-respiratory ontogeny and the transition to bimodal respiration in an air breathing fish, the blue gourami (Trichogaster trichopterus): Morphological and physiological development in normoxia and hypoxia.
- As selection pressures exist for not only adults, but for every life history stage, it is important to understand how environmental factors shape developing animals. Despite the significance placed on aquatic hypoxia as a driving force in the evolution of air breathing, this is the first known study to examine the effects of hypoxia on cardio-respiratory ontogeny of an air breathing fish. Blue gouramis are obligatory air breathing fish that possess a labyrinth-like structure that serves as the air breathing organ. Gouramis were reared for up to 90 d in normoxia or hypoxia, and morphological and physiological development was observed. Hypoxic larvae had increased lamellar and labyrinth organ surface areas. Bradycardia and increased gill ventilation rates were observed when larvae from either rearing group were briefly exposed to hypoxia. Hypoxic larvae also showed a reduced heart rate and gill ventilation rate in the absence of a hypoxic stimulus, possibly indicative of a more comprehensive, long-term respiratory plasticity. The similarity of routine oxygen consumption between rearing groups suggests that metabolic demand did not change for hypoxic larvae, but that they were more efficient at oxygen acquisition. This is further supported by increased resistance time of hypoxic gouramis to extreme hypoxia. The onset of air breathing was between 20 and 25 d post-fertilization, and was not affected by either rearing or exposure environment. It may be that this behavior is associated with the inability of smaller larvae to successfully overcome water surface tension, rather than with the necessity of aerial respiration at this stage. Hypoxia is commonly experienced by most air breathing fishes, and studies of hypoxia-induced developmental effects may provide critical insights into the evolution of air breathing. The studies presented here provide novel data on the plasticity of cardio-respiratory development of an air breathing fish reared in hypoxia, and can serve as a solid foundation for future studies. digital.library.unt.edu/ark:/67531/metadc11056/
- Effects of triclosan, triclocarban, and caffeine exposure on the development of amphibian larvae.
- Triclosan and triclocarban are antimicrobials found in numerous consumer products, while caffeine is the most commonly consumed stimulant by humans. This study was undertaken to determine the effects of triclosan, triclocarban, and caffeine on the development and physiology of amphibian larvae. LC50 values of triclosan and triclocarban were determined after 96 hours for three North American larval species: Acris crepitans blanchardii, Bufo woodhousii woodhousii, Rana sphenocephala, and for a common amphibian developmental model: Xenopus laevis. Amphibian larvae were most sensitive to triclosan and triclocarban exposure during early development based upon 96-hour LC50 values. Heart rates for X. laevis and North American larvae exposed to triclosan were variable throughout development. However, significantly lower heart rates were observed in all larvae exposed to triclocarban. Metabolic rates of X. laevis and R. sphenocephala larvae exposed to triclosan were significantly affected in larvae exposed to ½ LC50 and the LC50 concentration. Metabolic rates of X. laevis larvae exposed to triclocarban were significantly affected by exposure to ½ LC50 concentrations in three of four stages investigated. No significant differences were observed in North American larvae exposed to triclocarban. Tissue uptake, lipid uptake, tissue bioconcentration factor (BCF) and lipid BCF of triclosan and triclocarban were investigated in three developmental stages of X. laevis, and in one developmental stage of B. woodhousii woodhousii, and R. sphenocephala. For most tissue and lipid uptake values, a significant increase was observed as exposure concentration increased. Tissue and lipid BCF values were dependent upon both stage and species. Chronic and acute effects of caffeine were determined in X. laevis larvae. Acute 96-hour LC50 values in four developmental stages were > 75,000 ug L-1 caffeine and heart rates were significantly different at the two earliest developmental stages. Larvae chronically exposed to caffeine reached metamorphosis at the same time as controls. Changes in chronic heart rate were dependent upon stage of development and exposure concentration. This research indicates that the toxicity of amphibian larvae exposed to triclosan, triclocarban, and caffeine appears to be dependent upon species and developmental stage, with early developmental stages being most sensitive to contaminant exposure. digital.library.unt.edu/ark:/67531/metadc11016/
- Incubation humidity as an environmental stressor on the osmoregulatory developmental program of the chicken, Gallus gallus domesticus.
- Fetal programming results from stressors during fetal development and may influence the occurrence of disease later in life. Maternal nutritional status and/or environment can affect renal development by inducing limited nephron endowment at birth, which results in diseases such as hypertension and coronary heart disease in mammals. Birds are likely to be effective models for this process because, like mammals, they have high pressure cardiovascular systems, mammalian-type nephrons and are homeothermic. This project uses the chicken embryo to explore physiological responses of disrupted hydration state thereby providing insights into renal fetal programming. Under normal conditions the chorioallantoic membrane (CAM) and developing avian kidney work in unison to ensure a proper balance of ions and water within the egg. White leghorn chicken eggs were incubated at 37.5oC±0.5oC and either <35%, 55-60% (normal) or >85% relative humidity. Amniotic fluid serves as the drinking source for the embryo late in development; its composition is important to salt and water homeostasis. High amniotic fluid osmolality increased the blood osmolality for embryos exposed to low humidity incubation thereby indirectly influencing the renal developmental program of the embryos from this group. Indeed estimated filtering capacity was doubled in the low humidity group (6.77 ± 0.43 mm3) compared to normal (4.80 ± 0.33 mm3) and high (3.97 ± 0.30 mm3) humidity groups. The increased filtering capacity seen for those embryos from low humidity may indicate the ability for more efficient recovery of water if similarly stressed as an adult bird. All embryo populations maintained similar oxygen consumption (0.075 ml/min - 0.37 ml/min), hematocrit (15 % - 32 %) and hemoglobin values (4 g/dl - 9 g/dl), thus displaying control over these aspects of the internal environment despite the obvious environmental insult of extreme incubation humidity. These results signify the embryo's immature kidney, along with lower gastrointestinal tract, functions much like the adult form maintaining homeostasis, although the mechanisms may differ. The overall benefits of this research included better understanding of the role the kidney during embryonic development and determining whether environmental factors, such as humidity, leave an imprint on morphological and physiological aspects of the urinary system of the embryo and water compartments of the egg. digital.library.unt.edu/ark:/67531/metadc11055/
- Influence of stormwater drainage facilities on mosquito communities within the city of Denton, Texas.
- Weekly collections were conducted from May to December, 2007 (153 trap nights, total) in Denton, Texas, in and around large storm drains and overpass drainage facilities in residential and non-residential areas, using Centers for Disease Control (CDC) light traps and gravid traps. A total of 1964 mosquitoes were collected, representing 24 species within 6 genera: Aedes, Anopheles, Culiseta, Culex, Psorophora, and Uranotaenia. Culex was the most abundant genus, representing 75% of all mosquitoes collected; Aedes was the second most abundant, representing 12 % of all mosquitoes collected. Cx. quinquefasciatus was the dominant species collected via gravid traps; Cx. (Melanoconion) species were the dominant species collected via CDC light traps. Data of gravid traps and light traps were analyzed separately using nonparametric correlation analysis, comparing environmental data and physical characteristics to total abundance of mosquitoes. There was no significant correlation found when comparing the three dominant species collected in light traps (unidentified Cx. (Melanoconion) sp, Cx. quinquefasciatus, and Ae. vexans) to environmental characteristics and physical characteristics. Analysis of Cx. quinquefasciatus collected in gravid traps indicated no significant correlation between abundance, environmental data, and physical characteristics. Linear regression models were analyzed to determine if either environmental variables or physical characteristics of the drainage system explained the species abundance collected; no individual variable showed an association of significance. Analysis of Cx. quinquefasciatus collected in storm drains via gravid traps determined temperature to be the most important variable in determining population abundance and explained 99% of the population variability. digital.library.unt.edu/ark:/67531/metadc9765/
- Genetic mechanisms for anoxia survival in C. elegans.
- Oxygen deprivation can be pathological for many organisms, including humans. Consequently, there are several biologically and economically relevant negative impacts associated with oxygen deprivation. Developing an understanding of which genes can influence survival of oxygen deprivation will enable the formulation of more effective policies and practices. In this dissertation, genes that influence adult anoxia survival in the model metazoan system, C. elegans, are identified and characterized. Insulin-like signaling, gonad function and gender have been shown to influence longevity and stress resistance in the soil nematode, C. elegans. Thus, either of these two processes or gender may influence anoxia survival. The hypothesis that insulin-like signaling alters anoxia survival in C. elegans is tested in Aim I. The hypotheses that gonad function or gender modulates anoxia survival are tested in Aim II. Insulin-like signaling affects anoxia survival in C. elegans. Reduction of insulin-like signaling through mutation of the insulin-like receptor, DAF-2, increases anoxia survival rates in a gpd-2/3 dependent manner. The glycolytic genes gpd-2/3 are necessary for wild-type response to anoxia, and sufficient for increasing anoxia survival through overexpression. Gonad function and gender both affect anoxia survival in C. elegans. A reduction of ovulation and oocyte maturation, as measured by oocyte flux, is associated with enhanced anoxia survival in all cases examined to date. Reduction of function of several genes involved in germline development and RTK/Ras/MAPK signaling reduce ovulation and oocyte maturation while concurrently increasing anoxia survival. The act of mating does not influence anoxia survival, but altering ovulation through breeding or chemical treatment does. The male phenotype also increases anoxia survival rates independent of genotype. These studies have identified and characterized over ten different genotypes that affect adult survival of anoxia in C. elegans. Before these studies were conducted, there were no genes known to influence adult anoxia survival in C. elegans. Furthermore, these studies have begun to uncouple mechanisms of longevity and stress resistance. digital.library.unt.edu/ark:/67531/metadc9062/
- Morphological and physiological developmental consequences of parental effects in the chicken embryo (Gallus gallus domesticus) and the zebrafish larva (Danio rerio).
- Cardiac, metabolic and growth response of early-stage chicken embryos to perturbations in yolk environment was investigated. Also, effects of parental hypoxia exposure on hypoxia resistance, thermal tolerance and body length of zebrafish larvae were investigated. In the first study, thyroxine, triiodothyronine and testosterone produced differential effects on heart rate and development rate of chicken embryos during the first 4 days of development. Triiodothyronine caused a dose-dependent increase in heart rate when applied at 40 or 70 hours of age, while thyroxine caused a dose-dependent increase in heart rate when applied at 40 hours only. Testosterone and propyl-thiouracil (deiodinase antagonist) did not have an effect on heart rate. Development rate was not changed by thyroxine, triiodothyronine, testosterone or propyl-thiouracil, which suggested that heart rate changes did not result from changes in embryo maturity. In the second study, chicken embryos exposed to yolks of different bird species during early-stage embryonic development showed changes in heart rate, mass-specific oxygen consumption and body mass that scaled with the egg mass, incubation period length, and yolk triiodothyronine and testosterone levels of the species from which yolk was derived. In the third study, this phenomenon was investigated between layer and broiler chickens. Heart rate, oxygen consumption and body mass of broiler and layer embryos were significantly changed by a breed-specific change in yolk environment. Yolk triiodothyronine and testosterone concentrations of broiler and layer eggs did not suggest that these hormones were responsible for physiological and morphological changes observed. The final study demonstrated that hypoxia resistance and body lengths, but not thermal tolerance of zebrafish larvae was increased by parental hypoxia exposure. digital.library.unt.edu/ark:/67531/metadc9086/
- Home range analysis of rehabilitated and released great horned owls (Bubo virginianus) in Denton County, Texas, through radio telemetry.
- Raptor rehabilitation has become commonplace globally, yet studies on the survival and adaptation of great horned owls (Bubo virginianus) after release has been neglected to an appreciable extent. The primary objective of this study is to provide quantitative data on the success of rehabilitated and released great horned owls in the North Texas region. Owls (N=12) were rehabilitated and released onto the Ray Roberts Greenbelt Corridor in Denton County, Texas, and monitored using radio telemetry to evaluate home range (November 2002 - February 2005). With approximately 75% of the birds released for this study surviving until transmitter battery failure, it is believed that the rehabilitation process was successful for these birds. digital.library.unt.edu/ark:/67531/metadc5159/
- Optimization of Cell Culture Procedures for Growing Neural Networks on Microelectrode Arrays
- This thesis describes the development of an optimized method for culturing dissociated, monolayer neuronal networks from murine frontal cortex and midbrain. It is presented as a guidebook for use by cell culture specialists and laboratory personnel who require updated and complete procedures for use with microelectrode array (MEA) recording technology. Specific cell culture protocols, contamination prevention and control, as well common problems encountered within the cell culture facility, are discussed. This volume offers value and utility to the rapidly expanding fields of MEA recording and neuronal cell culture. Due to increasing interest in determining the mechanisms underlying Parkinson's disease, the newly developed procedures for mesencephalon isolation and culture on MEAs are an important research contribution. digital.library.unt.edu/ark:/67531/metadc5126/
- The role of prostaglandins, nitric oxide and oxygen in the ductus arteriosi of the pre-term chicken embryo (Gallus domesticus).
- The chicken ductus arteriosi (DA) are two embryonic blood vessels that shunt blood away from the non-ventilated lungs and towards the body and chorioallantoic membrane. I show that prostaglandins have a diminished role in maintaining chicken DA patency and nitric oxide inhibits oxygen induced contraction of the day 19 proximal DA in a time dependent manner. The pathways governing oxygen induced contraction in the chicken DA are similar to those found in mammals and include contributions from ROS, Kv channels, L-type Ca2+ channels, and the Rho kinase pathway. Longer exposure to high oxygen generates increased oxygen induced constriction of the day 19 DA that may be mediated through the Rho kinase pathway. digital.library.unt.edu/ark:/67531/metadc5173/
- Stream water quality corridor assessment and management using spatial analysis techniques: Introduction, evaluation, and implementation of the WQCM model.
- The rapid development of once-rural landscapes often produces detrimental effects on surface water quality entering local reservoirs through vulnerable stream channels. This study presents a methodology that incorporates geographic information systems (GIS) and remote sensing techniques for the creation of a stream corridor evaluation mechanism, coined the water quality corridor management (WQCM) model. Specifically, the study focuses on determining the viability of the WQCM model in assessing the stream corridor conditions within a northern Denton County pilot study region. These results will aid in the prediction and evaluation of the quality of stream water entering reservoirs that serve as the primary drinking water source for local municipalities. digital.library.unt.edu/ark:/67531/metadc3976/
- Bacterial challenge in Lumbricus terrestris: A terrestrial invertebrate immunotoxicity model.
- A bacterial challenge assay was developed utilizing the earthworm, Lumbricus terrestris, in order to assess potential immunotoxic effects from exposure to specific polychlorinated biphenyl congeners. Earthworms were inoculated with Aeromonous hydrophila, establishing a 10-day LD50. In vitro assays for effects of PCBs on phagocytosis agreed with mammalian studies, demonstrating potent suppression of phagocytosis by the non-coplanar PCB congener 138 and no suppression by the coplanar congener 126. However, when the effects of the two PCB congeners were evaluated for suppression of resistance to a whole animal infection challenge assay, coplanar PCB 126 decreased the ability of L. terrestris to withstand infection while non-coplanar PCB 138 did not. digital.library.unt.edu/ark:/67531/metadc3640/
- A contravention of established principles of interspecific allometric metabolic scaling in developing silkworms, Bombyx mori.
- Established interspecific metabolic allometric relationships do not adequately describe the complexity and variable physiological states of developing animals. Consequently, intraspecific allometric relationships of oxygen consumption and carbon dioxide production as a function of body mass; the respiratory quotient; the function of the silk cocoon; and body composition were investigated for each distinct developmental stage of the silkworm, Bombyx mori. Whole animal O2 consumption in Bombyx ranged from 0.00064 + 0.000047 ml O2 .hr-1 at larval instar I to 0.77 + 0.06 ml O2 .hr-1 in pre-pupal, falling to 0.21+ 0.01 ml O2 .hr-1 in the pupae. Those instars having a significant relationship between O2 consumption as a function of body mass, the slope of the line relating O2 consumption to body mass varied between 0.99 and 1.02, while across all instars the slope was 0.82. Developmental allometry should be presented for individual developmental stages because the individual allometric exponents of the stages can be significantly different from the overall allometric exponent throughout development and in some cases, the overall allometric exponent can be a statistical artifact. The first larval instar of Bombyx mori has the lowest cross sectional area of high metabolic tissue of the midgut (27%) and had one of the highest percentages of some metabolically inert tissues (i.e. lipid, 7.5%). Body composition of the first instar does not support the idea that smaller mass animals having the highest O2 consumption are composed of a greater percentage of metabolically active organs when compared to larger animals. However, this developmental stage has the highest percentage of the mitochondrial marker cytochrome oxidase, which correlates well with the high O2 consumption rate of the smaller mass. Therefore, established interspecific principles should not be assumed to function as valid models for intraspecific developmental relationships of metabolism as a function of body mass. Developmental allometry should include an analysis of individual stages of development as well as an analysis of development as a whole to gain a comprehensive understanding of the complexity of allometry of the developing animal such as the silkworm. digital.library.unt.edu/ark:/67531/metadc3704/
- Establishing genetic and physiological baselines for the black-tailed prairie dog (Cynomys ludovicianus).
- The black-tailed prairie dog (Cynomys ludovicianus) has experienced dramatic declines over much of its historical range due to habitat loss, plague, poisonings, and shootings. Many populations now occur as isolated genetic relicts. A multiple locus genetic profile was obtained using microsatellite analyses of six polymorphic nucleotide repeats from 319 black-tailed prairie dogs collected from 16 colonies throughout the state of Texas. This assessment revealed that existing populations have sufficient variation at all six loci to verify the usefulness of this approach as a primary genetic tool in conservation and preservation. The data reveals regional-dependent frequency patterns as well as support for founder/bottleneck effects for several of the 16 sites. Although the prairie dog population in Texas as a whole may appear genetically diverse, considerable genetic divergence has already occurred among the subpopulations (FST = 0.164). Isolation by distance is supported by genic differentiation analysis (P < 0.001) and pairwise correlation analysis between genetic distance and geographic distance (P < 0.001). Prairie dogs from six (COC, LUBA, LUBC, LUBD, LUBE, and TAR) of the original 16 sites have been relocated or exterminated, or were in the process of being relocated. Results indicated the following colonies (COT, DAL, HOW, and HUD) are of sufficient size and possess ample genetic diversity to be characterized as candidate foundation populations for future preservation efforts. The proximity of small colonies (< 20 hectares) such as HEMB, LUBB, and PEC, to other colonies should be examined to determine if they are isolated or part of a metapopulation. Colonies (HAR, HEMA, and SCH) with low genetic diversity would be ideal candidates for supplementation. Alternatively, these colonies could be relocated or blended with other similar but genetically distinct colonies. Baselines for healthy, pet prairie dog hematology and blood chemistries were also established. Results signify that data gathered from pet prairie dog blood analyses should be referenced against hematology and blood chemistry baselines established using pet prairie dog subjects. digital.library.unt.edu/ark:/67531/metadc3705/
- Influence of parental swimming stamina on the cardiac and metabolic performance of larval zebrafish (Danio rerio).
- Superior swimming stamina in adult fish is presumably passed on to their offspring, but the ontogeny of the appearance of superior stamina and the requisite enhanced cardio-respiratory support for locomotion in larval fishes has not been determined. Is the expression of the suite of parental traits enabling superior swimming stamina in their offspring dependent upon their achieving juvenile/adult morphology, or does it appear earlier in their larvae? To answer this, adults were classified into three groups based on swimming stamina, followed by measurement of length, mass, and width. Larval offspring from the two parental groups -high stamina larvae (HSL) and low stamina larvae (LSL)- were reared at 27°C in aerated water (21% O2). Routine and active heart rate, routine and active mass specific oxygen consumption were recorded through 21dpf, and cost of transport (COT) and factorial aerobic scope were derived from oxygen consumption measurements. Routine heart rate at 2dpf of LSL was 164 ± 1 b·min-1, compared to only 125 ± 2 b·min-1 for HSL. Routine heart rate subsequently peaked at 203 ± 1 b·min-1 at 5dpf in the HSL group, compared to 207 ± 1 b·min-1, at 4dpf in the LSP larvae. Active heart rate at 5 dpf of LSL was 218 ± 2 b·min-1 compared to 216 ± 2 b·min-1 for HSL. Active heart rate increased slightly to 227 ± 2 b·min-1 for LSL before decreasing again, while active heart rate remained relatively constant for HSL. Routine O2 consumption at 2dpf of HSL was 0.09 μmol·mg-1·hr-1, compared to 0.03 μmol·mg-1·hr-1 in LSL. Routine O2 consumption subsequently peaked at 0.70 μmol·mg-1·hr-1 at 9dpf in the HSL, compared to 0.71 μmol·mg-1·hr-1, at 9dpf in the LSL. These values dramatically decreased before leveling off at around 0.20 μmol·mg-1·hr-1 and 0.15 μmol·mg-1·h-1, respectively. Active O2 consumption at 5dpf for HSL was 0.38 μmol·mg-1·hr-1, compared to 0.57 μmol·mg-1·hr-1 for LSL. Active O2 consumption subsequently peaked at 0.97 μmol·mg-1·hr-1 at 10dpf in HSL, compared to 1.19 μmol·mg-1·hr-1 at 7dpf in LSL. These values also dramatically decreased and leveled off. Significant differences (p < 0.05) in heart rate and oxygen consumption persisted through 21dpf. The onset of differences observed in routine and active heart rate in early larvae, correlated with parent stamina, show that juvenile or adult features are not required as a precondition for the emergence of phenotypic physiological differences. digital.library.unt.edu/ark:/67531/metadc3669/
- Coelomic fluid protein profile in earthworms (Lumbricus terrestris) following bacterial challenge.
- Proteomic techniques were used to evaluate the protein profile of the earthworm, (Lumbricus terrestris), following a bacterial challenge. One control group received no injection; a second control group received injections of phosphate buffer solution (PBS). The experimental group received injections of PBS containing (Aeromonas hydrophila). After incubation for 12 hours at 20°C, coelomic fluid was collected from each group for analysis by 2-D electrophoresis. There were significant differences in spot appearance and density between control and experimental groups. Sixteen spots showed a two-fold increase in density and 63 showed at least a two-fold decrease in density between samples from control and bacteria-challenged earthworms, respectively, suggesting up- and down-modulation of proteins potentially involved in the earthworm's response to bacterial challenge. digital.library.unt.edu/ark:/67531/metadc5476/
- Gene Flow among Populations of the Mayfly Epeorus pleuralis (Banks 1910) (Ephemeroptera: Heptageniidae) in Three Adjacent Appalachian Headwater Streams
- Dispersal of aquatic insects is difficult to measure with traditional direct trapping methodologies. However, genetic markers are an ideal surrogate to indirectly infer dispersal and gene flow. For this research, a portion of the cytochrome oxidase I gene was used to evaluate gene flow and dispersal of Epeorus pleuralis located in the northern Appalachian headwater streams of the Allegheny, Genesee, and Susquehanna watersheds. A total of 536 basepairs from 16 individual insects were used for analysis. Thirteen haplotypes were discovered, two of which were shared between the Allegheny and Genesee streams. Although no shared haplotypes were found in the Susquehanna, analysis of molecular variance results suggest that there is not a significant genetic difference between the three populations and attributes the majority of variation to within population differences. digital.library.unt.edu/ark:/67531/metadc5286/
- Leaf elemental analysis and growth characteristics of mycorrhizal treated post oak seedlings via particle induced X-ray emission spectroscopy.
- Growth and element assimilation was investigated in post oak seedlings exposed to four different treatment combinations of fertilization and ectomycorrhizal inoculation. Element concentration in excised leaves was analyzed via particle induced X-ray emission spectrometry with a 1.8 MeV proton macrobeam. Mean growth was significantly different across the treatment groups as well as mean concentration of Mg, Al, S, K, Ca, Fe, Cu, and Zn. The data suggest that fertilization rather than mycorrhizal inoculation had a stronger influence on plant growth and nutrient uptake. A follow up study was conducted with a 3 MeV microbeam. A 850 μm2 scanned area of a post oak leaf produced topographical maps of 11 elements. digital.library.unt.edu/ark:/67531/metadc5295/
- The Life History and Contributions to the Ecology of Camelobaetidius variabilis Wiersema 1998 (Ephemeroptera: Baetidae) in Honey Creek, Oklahoma
- A study of the life history and ecology of Camelobaetidius variabilis was conducted in Honey Creek, OK from February 2003-April 2004. Nymph development was assessed using changes in external morphology. Laboratory reared nymphs were used to calculate number of degree days to complete development (772 degree days at 20.8° C ±.38° C), which was used to determine voltinism. Field collected nymph microhabitat distribution was used in assessing microhabitat distribution. Nymphal thermoregulation was assessed during the winter and spring by comparing nymphal numbers present in shaded and un-shaded habitats. Camelobaetidius variabilis nymphs showed preference for algal microhabitats during the spring and leaf packs in the winter. Nymphs inhabited leaf packs to increase metabolic rate during the winter. Increased temperatures aid in development of nymphs. Camelobaetidius variabilis exhibited a multivoltine life cycle with six overlapping generations. digital.library.unt.edu/ark:/67531/metadc4944/
- Mouse cortical cholinergic neurons: Ontogeny of phenotypes in vivo and in vitro.
- The development of cholinergic neurons in mouse frontal cortex was studied both in vivo and in vitro by immunocytochemistry with an antibody to choline acetyltransferase (ChAT), the enzyme responsible for acetylcholine synthesis. While cortical cholinergic neurons have previously been characterized in rat cortex, up until very recently, intrinsic cortical cholinergic neurons were considered to be absent in mouse, and little is known about their development or phenotypic characteristics. The present study found no ChAT-positive neurons in mouse frontal cortex on postnatal day 0 (P0, the day of birth). On P7 there were few, faintly stained, ChAT-positive neurons. The numerical density of ChAT-positive neurons increased substantially with age, from none on P0, to 9.2 + 1.4 on P7, to 14.8 + 0.9 on P16, and 41.6 + 3.9 in adulthood. Considering that the numerical density of total neurons decreases during this postnatal period, the data represent a marked developmental increase in the percentage of cholinergic neurons. The development of cholinergic neurons showed very similar timelines in rat and mouse frontal cortex. Cultures prepared from mouse frontal cortex on embryonic day 16 were maintained for 25, 76, or 100 days in vitro (div). The percentage of ChAT-positive neurons was considerably higher than in vivo, ranging from a mean 28% to 31% across the three age (div) groups. With increasing age of the cultures, the numerical density of total neurons and ChAT-positive neurons decreased while the percentage of ChAT-positive neurons did not change significantly. These observations suggest some temporal stability in the cultures. Using dual immunofluorescence, ChAT-positive neurons were tested for colocalization with GAD or TH. The majority of ChAT-positive neurons colocalized with GAD, both in vitro and in vivo. However, ChAT did not colocalize with TH, either in vitro or in vivo. Our comparison of intact frontal cortex and cultures suggest that while the percentage of cholinergic neurons was greater in the cultures, the cholinergic neurons developed phenotypic similarities in vitro and in vivo. digital.library.unt.edu/ark:/67531/metadc4890/
- Mutation of Polaris, an Intraflagellar Transport Protein, Shortens Neuronal Cilia
- Primary cilia are non-motile organelles having 9+0 microtubules that project from the basal body of the cell. While the main purpose of motile cilia in mammalian cells is to move fluid or mucus over the cell surface, the purpose of primary cilia has remained elusive for the most part. Primary cilia are shortened in the kidney tubules of Tg737orpk mice, which have polycystic kidney disease due to ciliary defects. The product of the Tg737 gene is polaris, which is directly involved in a microtubule-dependent transport process called intraflagellar transport (IFT). In order to determine the importance of polaris in the development of neuronal cilia, cilium length and numerical density of cilia were quantitatively assessed in six different brain regions on postnatal days 14 and 31 in Tg737orpk mutant and wildtype mice. Our results indicate that the polaris mutation leads to shortening of cilia as well as decreased percentage of ciliated neurons in all brain regions that were quantitatively assessed. Maintainance of cilia was especially affected in the ventromedial nucleus of the hypothalamus. Furthermore, the polaris mutation curtailed cilium length more severely on postnatal day 31 than postnatal day 14. These data suggests that even after ciliogenesis, intraflagellar transport is necessary in order to maintain neuronal cilia. Regional heterogeneity in the effect of this gene mutation on neuronal cilia suggests that the functions of some brain regions might be more compromised than others. digital.library.unt.edu/ark:/67531/metadc4856/
- Functional and Categorical Analysis of Waveshapes Recorded on Microelectrode Arrays
- Dissociated neuronal cell cultures grown on substrate integrated microelectrode arrays (MEAs) generate spontaneous activity that can be recorded for up to several weeks. The signature wave shapes from extracellular recording of neuronal activity display a great variety of shapes with triphasic signals predominating. I characterized extracellular recordings from over 600 neuronal signals. I have preformed a categorical study by dividing wave shapes into two major classes: (type 1) signals in which the large positive peak follows the negative spike, and (type 2) signals in which the large positive peak precedes the negative spike. The former are hypothesized to be active signal propagation that can occur in the axon and possibly in soma or dendrites. The latter are hypothesized to be passive which is generally secluded to soma or dendrites. In order to verify these hypotheses, I pharmacologically targeted ion channels with tetrodotoxin (TTX), tetraethylammonium (TEA), 4-aminopyridine (4-AP), and monensin. digital.library.unt.edu/ark:/67531/metadc4746/
- The stonefly genus Isogenoides Klapálek (Plecoptera: Perlodidae) of North America: Systematics, behavior and ecology.
- The stonefly genus Isogenoides is revised following a holomorphological approach utilizing traditional morphology and behavioral lines of evidence. Species keys are provided for all life stages. One species, I. krumholzi (Ricker) is considered a synonym of I. doratus (Frison). Detailed species descriptions are provided for males, females, nymphs and ova. Distributions are updated utilizing all known published accounts and materials examined. The vibrational communication (drumming) behavior is reported for males and all but one species for females. The signals were species-specific and ranged in complexity from ancestral sequenced duets to derived grouped exchanges. I. olivaceus is least specialized, having mostly sequenced duets, and I. zionensis most specialized, displaying ancestral sequenced, derived grouped and complex derived exchanges containing both sequenced and grouped elements. Laboratory egg incubation experiments over a 2-4 year period show that Isogenoides has a great capacity for extended, sometimes-asynchronous diapause and hatching. The eggs of six species were incubated at a single, ca. simulated San Miguel River, Colorado, seasonal temperature regime. Direct hatch within two weeks occurred only for I. zionensis (Leopard Creek, Colorado) with small numbers hatching again after one, two, and four years. Eggs of I. doratus and I. varians hatched after an over summer, 3-5 month diapause, and I. varians again in August the next year. Populations of I. colubrinus, I. elongatus, I. frontalis and San Miguel River, I. zionensis began hatching after a 9-11 month diapause and again during spring-summer temperatures in 2nd through 4th years. I. zionensis in the San Miguel River, Colorado, exhibited a semivoltine life cycle over the two-year study period. Adults emerged in June-July when stream temperature reached ca. 11-17°C. Reared females at Quartz Creek, Pitkin, Colorado, deposited up to three egg batches. Mean fecundity of females was 691 egg/female. Oviposition in the field was observed and described. Nymphal growth was exponential from June to December, followed by slow growth until April, then declined until emergence. The greatest growth occurred between July and December as stream temperature decreased to minimum and maximum size was obtained in March while stream temperature began to increase. digital.library.unt.edu/ark:/67531/metadc4747/