UNT Theses and Dissertations - 234 Matching Results

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The Biogeographic Distribution of Caddisflies (Insecta: Trichoptera) within the South-Central United States

Description: Through the use of natural history records, published literature, and personal sampling (2011-2016) a total of 454 caddisfly species represented by 24 families and 93 genera were documented from the south-central United States. Two Hydroptilidae species were collected during the 2011-2016 collection efforts that are new to the region: Hydroptilia scheringi and Mayatrichia tuscaloosa. Eightteen species are endemic and 30 are considered species of concern by either federal or state agencies. The … more
Date: May 2018
Creator: Perry, Heather Ann
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Biogeographic Relationships of Pocket Gophers (Geomys breviceps and Geomys bursarius) in the Southeastern Portion of Their Ranges

Description: 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 ectopa… more
Date: August 1998
Creator: Elrod, Douglas Allen
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Biogeography of Montane Mammals on the Colorado Plateau and Adjacent Regions

Description: This study identifies the biogeographic factors that structure small mammal communities on mountains of the Colorado Plateau and adjacent regions. Forty six isolated ranges were characterized across a 5-state study area encompassing the Colorado Plateau, including the central high plateaus of Utah and the Basin and Range Province (i.e. the Great Basin and mountains of Arizona and New Mexico). Presence/absence data of 25 montane mammal species were used to explore the interactions between histor… more
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Date: May 2004
Creator: Carr, Carla B.
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Biological and Toxicological Responses Resulting from Dechlorination of a Major Municipal Wastewater Treatment Plant Discharge to the Trinity River

Description: Federal regulations such as the Clean Water Act (P.L. 92-500), and its amendments, direct the Environment Protection Agency (EPA) to implement programs to control the releases of conventional pollutants and toxics into the waterways of the United States. The EPA began requiring treatment plants to conduct toxicity tests (biomonitoring) of their effluent discharges. To control toxicity caused by chlorination of wastewater discharges, the EPA also began requiring some treatment facilities to dech… more
Date: August 1995
Creator: Guinn, Richard J. (Richard Joe)
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Biological Nitrogen Fixation in Two Southwestern Reservoirs

Description: This investigation has determined the presence of biological nitrogen fixation in two reservoirs in the southwestern United States: Lake Arlington and Lake Ray Hubbard. Subsequent tests have gathered baseline data on the effects of various biological, chemical, and physical parameters on in situ nitrogen fixation in these reservoirs. Of specific importance is the relationship between nitrogen fixation arid occasional blooms of blue-green algae which produce such problems as testes and odors in … more
Date: August 1973
Creator: Lawley, Gary G.
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Biology and Production of Net-Spinning Caddisflies (Hydropsychidae And Philopotamidae) in a Regulated Portion Of The Brazos River, Texas

Description: Four species of net-spinning caddisflies, Hydropsyche simulans Ross, Cheumatopsyche lasia Ross, Cheumatopsyche campyla Ross and Chimarra obscura (Walker) are common in the regulated portions of the Brazos River. Hydropsyche simulans spun capture nets with the largest meshdimensions; the two Cheumatopsyche species' nets had the next largest meshes, and Chimarra obscura spun nets with the smallest dimensions. Cheumatopsyche lasia and C. campyla constructed nets with similar sized meshes. The numb… more
Date: May 1984
Creator: Malas, Diane M. (Diane Mary)
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Blood Pressure Regulation During Simulated Orthostatism Prior to and Following Endurance Exercise Training

Description: Cardiovascular responses and tolerance to an orthostatic stress were examined in eight men before and after eight months of endurance exercise training. Following training, maximal oxygen consumption and blood volume were increased, and resting heart rate reduced. Orthostatic tolerance was reduced following training in all eight subjects. It was concluded that prolonged endurance training decreased orthostatic tolerance and this decrease in tolerance appeared associated with attenuated barorefl… more
Date: May 1992
Creator: Stevens, Glen Harold John
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The Bobwhite Population Decline: Its History, Genetic Consequences, and Studies on Techniques for Locating and Assessing Current Populations

Description: The northern bobwhite (Colinus virginianus) population decline is a severe, rangewide phenomenon beginning >150 years ago and continuing today. In this investigation, I: 1. document the timeline of bobwhite population decline and unintended genetic consequences of attempted remedies, 2) develop a model useful for predicting possible locations of potentially sustainable bobwhite populations in semiarid rangeland in Texas and Oklahoma, and 3) examine the relationship between population monitoring… more
Date: May 2019
Creator: Whitt, Jeffrey Glen
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Breeding Ecology and Migratory Connectivity of Passerines in the World's Southernmost Forests

Description: In the extensive and remote sub-Antarctic forests of South America, birds are the dominant terrestrial vertebrates. Despite considerable efforts to understand the ecology of birds breeding in these forests, our current knowledge for many species is still incomplete. During three breeding seasons (2014 – 2017), I studied the breeding ecology of the five most abundant open-cup forest-dwelling passerines in the sub-Antarctic forest of Navarino Island, Chile (55°04′S, 67°40′W). There were differenc… more
Date: May 2021
Creator: Jara Millar, Rocio Fernanda
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Carbon Flux in Reservoir Sediments

Description: The central objective of the study was to fractionate sedimenting organic materials according to their source (allochthonous or autochthonous) and ultimately to determine the degree of biodegradability of contributions from either source with particular reference to activities at the mud-water interface.
Date: May 1973
Creator: Newton, Charles Eugene
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Cardio-Respiratory Ontogeny and the Transition to Bimodal Respiration in an Air Breathing Fish: Morphological and Physiological Development in Normoxia and Hypoxia.

Description: 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 th… more
Date: August 2009
Creator: Blank, Tara M.
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Cardiovascular Fetal Programming in Quail (Colinus virginianus), An Avian Comparative Model

Description: The consequences of early embryonic insults and how they affect subsequent life reflects the emerging concept of "fetal programming". The aim of this project is to study the effects of embryonic insults as they subsequently manifest themselves in adults, with emphasis on the heart and vasculature. My experiments establish that fetal programming operates on the bobwhite quail inducing similar changes as those observed in mammalians and other birds. The quail's fast development provides reliable … more
Date: December 2016
Creator: Flores Santin, Josele R.
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Cellular Biomarkers for Measuring Toxicity of Xenobiotics: Effects of PCBs on Earthworm Lumbricus Terrestris Coelomocytes

Description: The research presented herein provides information on coelomocyte (leukocyte) collection, function and immunotoxicity from polychlorinated biphenyls (PCB) in the earthworm Lumbricus terrestris. Research was undertaken as part of an overall goal to develop a well-documented and scientifically valid non-mammalian surrogate immunoassay with the earthworm Lumbricus terrestris to assess immunotoxic potential of xenobiotics. The principal objectives were to: (1) Develop an extrusion model for analyzi… more
Date: May 1991
Creator: Eyambe, George Sona
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Ceramide Biosynthesis and NEET Proteins Impact Development, Function, and Maintenance of the Caenorhabditis elegans Germline

Description: I used the C. elegans genetic model to examine the role of ceramide biosynthesis (sphingolipid pathway) and iron regulation and found that each process impacts germline development and function. Using a sphingolipid specific antibody mAb15B4, I found that sphingolipids are associated with germ granules (P granules) within C. elegans and zebrafish; thus, suggesting conservation of macromolecules associated with germ granules. Phenotype analysis of ceramide biosynthesis mutants in C. elegans reve… more
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Date: August 2019
Creator: King, Skylar Dawn
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Characteristics of Primary Cilia and Centrosomes in Neuronal and Glial Lineages of the Adult Brain

Description: 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 … more
Date: May 2015
Creator: Bhattarai, Samip Ram
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Characterization of Aspartate Transcarbamoylase in the Archaebacterium Methanococcus Jannaschii

Description: Asparate transcarbamoylase catalyzes the first committed step in the de novo synthesis of pyrmidine nucleotides UMP, UDP, UTP, and CTP. The archetype enzyme found in Escherichia coli (310 kDa) exhibits sigmodial substrate binding kinetics with positive control by ATP and negative control with CTP and UTP. The ATCase characterized in this study is from the extreme thermophilic Archaebacterium, Methanococcus jannaschii. The enzyme was very stable at elevated temperatures and possessed activity fr… more
Date: December 1996
Creator: Stewart, John E. B. (John Edward Bakos)
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Characterizing the Molecular Changes of Austrofundulus limnaeus As It Develops Towards and Enters Diapause II

Description: 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,… more
Date: December 2015
Creator: Toni, Lee S.
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CO2 Transport and Acid-Base Status during Fluctuations in Metabolic Status in Reptiles

Description: Reptiles can often experience perturbations that greatly influence their metabolic status (e.g., temperature, exercise, digestion, and ontogeny). The most common cause of fluctuations in metabolic status in post-embryonic reptiles is arguably digestion and physical activity (which will be further referred to as exercise). The objective of this thesis is to determine the mechanisms involved in CO2 transport during digestion, determine the mechanisms that allow for the maintenance of acid-base ho… more
Date: December 2021
Creator: Conner, Justin Lawrence
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Comparative biochemistry and genetic analysis of nucleoside hydrolase in Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens.

Description: The pyrimidine salvage enzyme, nucleoside hydrolase, is catalyzes the irreversible hydrolysis of nucleosides into the free nucleic acid base and D-ribose. Nucleoside hydrolases have varying degrees of specificity towards purine and pyrimidine nucleosides. In E. coli, three genes were found that encode homologues of several known nucleoside hydrolases in protozoa. All three genes (designated yaaF, yeiK, and ybeK) were amplified by PCR and cloned. Two of the gene products (yeiK and ybeK) encode … more
Date: December 2002
Creator: Fields, Christopher J.
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Comparative Morphology of Sensilla Styloconica on the Proboscis of North American Nymphalidae and Other Selected Taxa: Systematic and Ecological Considerations.

Description: Sensilla styloconica on the proboscis of 107 species of North American and tropical butterflies were comparatively studied using the scanning electron microscope. Focus was on 76 species of North American Nymphalidae representing 45 genera and 11 subfamilies. Nomenclature for generalized and specific types of nymphalid sensilla is proposed. Written descriptions and micrographs are presented for each species studied. Morphological features were generally consistent for all or most species withi… more
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Date: December 2001
Creator: Petr, Daniel
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The Consequences of Early Life Stage Thyroid Suppression on Immune Function in the Fathead Minnow (Pimephales promelas)

Description: Current evidence suggests that thyroid hormones (THs) may impact development of the immune system. However, studies that explore the role of THs in immune development are limited, and the mechanisms leading to alterations in immune function are poorly understood. It is important to elucidate the role of THs in immune development given that many environmental contaminants have been shown to disrupt TH homeostasis and may also have negative impacts on the immune system. As such, the main goal of … more
Date: May 2020
Creator: Thornton Hampton, Leah Marie
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A Contravention of Established Principles of Interspecific Allometric Metabolic Scaling in Developing Silkworms, Bombyx Mori.

Description: Established interspecific metabolic allometric relationships do not adequately describe the complexity and variable physiological states of developing animals. Consequently, intraspecific allometric relationships of oxygen consumption and carbon dioxide production as a function of body mass; the respiratory quotient; the function of the silk cocoon; and body composition were investigated for each distinct developmental stage of the silkworm, Bombyx mori. Whole animal O2 consumption in Bombyx r… more
Date: May 2007
Creator: Blossman-Myer, Bonnie
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