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Effects of Deepwater Horizon Crude Oil on Visual Function in Teleost Fishes (open access)

Effects of Deepwater Horizon Crude Oil on Visual Function in Teleost Fishes

The Deepwater Horizon oil spill released millions of barrels of oil into the Gulf of Mexico, impacting economically and ecologically important fishes. Polycyclic aromatic hydrocarbons (PAHs) present in the oil have been shown to cause developmental impairments in early life stage fishes, such as morphological and behavioral changes related to eye formation and visual processing following PAH exposure. Prior research reported reduced eye growth in open water, pelagic species, as well as reduced photoreceptor-specific transcription factors associated with eye development following exposure to crude oil. Though changes in transcriptomic-level pathways associated with vision and visual processing have been reported, it has yet to be determined how these changes relate to physiological or behavioral-level effects in fish. Therefore, the present studies evaluated the effect of weathered crude oil on eye development and visual function in mahi-mahi, red drum, sheepshead minnow, and zebrafish larvae. Fish were assessed through several visually-mediated behavioral assays, analyzed histologically and immunohistologically, along with subsequent transcriptomic analyses and associated gene expression changes. Larvae exposed to crude oil experienced significantly reduced abilities to exhibit optomotor or optokinetic responses relative to controls, with associated reductions in retinal development. Furthermore, genes associated with eye development and phototransduction were downregulated, with subsequent …
Date: August 2018
Creator: Magnuson, Jason T
System: The UNT Digital Library
Exposure to Nanomaterials Results in Alterations of Inflammatory and Atherosclerotic Signaling Pathways in the Coronary Vasculature of Wildtype Rodents (open access)

Exposure to Nanomaterials Results in Alterations of Inflammatory and Atherosclerotic Signaling Pathways in the Coronary Vasculature of Wildtype Rodents

Cardiovascular disease (CVD) is the leading cause of death for people of most ethnicities on a global scale, and countless research efforts on the pathology of CVD has been well-characterized over the years. However, advancement in modern technologies, such as nanotechnology, has generated environmental and occupational health concerns within the scientific community. Current investigation of nanotoxicity calls into question the negative effects nanomaterials may invoke from their environmental, commercial, and therapeutic usage. As a result, further research is needed to investigate and characterize the toxicological implications associated with nanomaterial-exposure and CVD. We investigated the toxicity of multi-walled carbon nanotubes (MWCNT) and titanium dioxide (TiO2), which are two prominently used nanomaterials that have been previously linked to upregulation of inflammatory and atherogenic factors. However, the mechanistic pathways involved in these nanomaterials mediating detrimental effects on the heart and/or coronary vasculature have not yet been fully determined. Thus, we utilized two different routes of exposure in rodent models to assess alterations in proinflammatory and proatherogenic signaling pathways, which are represented in contrast throughout the dissertation. In our MWCNT study, we used C57Bl/6 mice exposed to MWCNTs (1 mg/m3) or filtered air (FA-Controls), via inhalation, for 6 hr/d for 14d. Conversely, intravenous TiO2 …
Date: August 2018
Creator: Davis, Griffith M.
System: The UNT Digital Library
Genomic Island Discovery through Enrichment of Statistical Modeling with Biological Information (open access)

Genomic Island Discovery through Enrichment of Statistical Modeling with Biological Information

Horizontal gene transfer enables acquisition and dissemination of novel traits including antibiotic resistance and virulence among bacteria. Frequently such traits are gained through the acquisition of clusters of functionally related genes, often referred to as genomic islands (GIs). Quantifying horizontal flow of GIs and assessing their contributions to the emergence and evolution of novel metabolic traits in bacterial organisms are central to understanding the evolution of bacteria in general and the evolution of pathogenicity and antibiotic resistance in particular, a focus of this dissertation study. Methods for GI detection have also evolved with advances in sequencing and bioinformatics, however, comprehensive assessment of these methods has been lacking. This motivated us to assess the performance of current methods for identifying islands on broad datasets of well-characterized bacterial genomes and synthetic genomes, and leverage this information to develop a novel approach that circumvents the limitations of the current state-of-the-art in GI detection. The main findings from our assessment studies were 1) the methods have complementary strengths, 2) a gene-clustering method utilizing codon usage bias as the discriminant criterion, namely, JS-CB, is most efficient in localizing genomic islands, specifically the well-studied SCCmec resistance island in methicillin resistant Staphylococcus aureus (MRSA) genomes, and 3) …
Date: August 2018
Creator: Jani, Mehul
System: The UNT Digital Library
Implications of Diet in Cardiovascular Disease Risk: Postprandial Changes in Circulating Monocytes and Endotoxemia (open access)

Implications of Diet in Cardiovascular Disease Risk: Postprandial Changes in Circulating Monocytes and Endotoxemia

It is well established that continual consumption of a diet high in fat leads to the development of chronic conditions such as obesity, cardio metabolic syndrome, and atherosclerosis that are associated with high incidence of cardiovascular disease. Recent studies have identified endotoxin-derived inflammation as a major diving force for the development of these conditions. Our laboratory has recently demonstrated that consumption of a single high-fat meal results in acute postprandial endotoxemia and alters monocyte cell surface adhesion molecule expression and scavenger receptor CD36 expression. These collective projects describe our efforts to understand the physiological significance of these postprandial changes and if supplementation with spore-based probiotics are able to provide any form of protection against these responses that are associated with the onset of atherogenesis.
Date: August 2018
Creator: Venable, Andrea Henning
System: The UNT Digital Library
Resistance Exercise and Alcohol: Combined Effects on Physiology and Performance (open access)

Resistance Exercise and Alcohol: Combined Effects on Physiology and Performance

Resistance exercise (RE) training is a well-known and effective method for promoting increases in muscle mass and strength. A single bout of RE induces physiological disturbances that require coordinated activation of the immune system and intramuscular signaling in order to return the tissue to homeostasis and adapt to the RE challenge. On the other hand, acute binge alcohol consumption can affect the immune response to an inflammatory challenge, intramuscular anabolic signaling, and muscle protein synthesis, and the effects of alcohol on these processes are opposite that of RE. Furthermore, individuals who report more frequent exercise also report a greater frequency of binge drinking. However, few investigations exist regarding the effects of binge alcohol consumed after a bout of RE on RE-induced physiological changes and performance recovery. Therefore, the overarching purpose of the investigations contained within this dissertation was to investigate the effect of alcohol consumed after RE on the RE-induced changes in mTOR pathway signaling, muscle protein synthesis, inflammatory capacity, strength recovery, and power recovery. Although RE increased mTOR pathway signaling and inflammatory capacity after exercise and reduced maximal strength and explosive power the day after exercise, we observed no effects of alcohol (1.09 g ethanol∙kg-1 lean body mass, designed …
Date: August 2018
Creator: Levitt, Danielle E.
System: The UNT Digital Library
The Role of Thyroid Hormone on the Development of Endothermy in White Leghorn Chickens (Gallus gallus) (open access)

The Role of Thyroid Hormone on the Development of Endothermy in White Leghorn Chickens (Gallus gallus)

As chickens hatch, there is a rapid change in their physiology and metabolism associated with attaining endothermy. It is thought that thyroid hormones (TH) play a major role in regulating developmental changes at hatching. In birds, TH regulates skeletal muscle growth, which has a direct impact on the chick's ability to thermoregulate via shivering thermogenesis. To better understand the role of TH in the timing of hatching, development of thermogenic capacity, and metabolic rate, we manipulated plasma TH levels in chicken embryos beginning at 85% development (day 17 of a 21 day incubation) with either thyroperoxidase inhibitor methimazole (MMI) or supplemental triiodothyronine (T3). After TH manipulation, we characterized O2 consumption and body temperature in the thermal neutral zone and during gradual cooling. Externally pipped embryos and 1 day post hatch (dph) chicks were cooled from 35 to 15°C. Manipulation of TH altered the timing of hatching, accelerating hatching under hyperthyroid conditions and decelerating hatching with hypothyroid conditions. Cohen's d revealed a large effect size on body temperature (Tb) of EP embryos of hypothyroid animals when compared to euthyroid animals in environmental temperatures of 32°C to 15°C, which was not seen in 1dph animals. Hyperthyroid EP animals were able to maintain …
Date: August 2018
Creator: Rippamonti, Jessica D.
System: The UNT Digital Library
The Role of Transmembrane Protein 59 in Thrombocyte Function and the Effect of MS-222 on Hemostasis in Zebrafish (open access)

The Role of Transmembrane Protein 59 in Thrombocyte Function and the Effect of MS-222 on Hemostasis in Zebrafish

Transmembrane protein 59 (tmem59) is a gene that encodes a protein involved in autophagy and apoptosis in human. A previous study in zebrafish showed that tmem59 mRNA was several folds higher in thrombocytes than those found in red blood cells (RBCs). Therefore, we hypothesized that tmem59 has a role in thrombocytes function. We injected a hybrid of control vivo-morpholino (cVMO) and tmem59 specific antisense standard oligonucleotide (tmem59SO) into adult zebrafish to knockdown tmem59.This piggyback knockdown approach resulted in fish that had more bleeding in gill bleeding assay than the control fish. The thrombocytes fromtmem59 knockdown zebrafish aggregated faster with ADP and collagen agonists. Also, the number of blood cells was reduced after the knockdown of tmem59. We also found the effects of MS-222 anesthesia on hemostasis and found that the bleeding was reduced yielding less blood and the blood cell counts increased probably due to vasoconstriction of the blood vessels. In summary, we found tmem59 is a negative regulator of hemostasis and inferred that anesthesia should be avoided in hemostasis studies.
Date: August 2018
Creator: Deebani, Afnan Omar M.
System: The UNT Digital Library