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The Bobwhite Population Decline: Its History, Genetic Consequences, and Studies on Techniques for Locating and Assessing Current Populations (open access)

The Bobwhite Population Decline: Its History, Genetic Consequences, and Studies on Techniques for Locating and Assessing Current Populations

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 data and meteorological factors. While breeding season call counts of male bobwhite have been used for >70 years to provide estimates of fall populations for hunting, most studies of call counts have focused on mathematics and statistical accuracy of the count, largely overlooking the influence of meteorological factors on call counts. Here, I present the results of >4,400 individual point counts and examine their relationship with meteorological variables recorded at each stop. Humidity was positively correlated with the number of birds recorded (ρ = 0.275, p < 0.001) and temperature was negatively correlated (ρ = -0.252, p < 0.001). The number of birds recorded was significantly higher in wet years than in drought years. There was no significant correlation between wind velocity and number of birds recorded. These results suggest that, while weather …
Date: May 2019
Creator: Whitt, Jeffrey Glen
System: The UNT Digital Library
Antimicrobial and Anti-Platelet Activity in Botanical Extracts of Plants Collected in Northern Thailand (open access)

Antimicrobial and Anti-Platelet Activity in Botanical Extracts of Plants Collected in Northern Thailand

The purpose of my research work was to assess a variety of Northern Thailand plants tissue extracts for antibacterial and anti-platelet aggregation activity. The Minimum Inhibitory Concentration assay method was used to assess antimicrobial activity of plant extracts, while the Zebrafish Platelet Aggregation Assay and the in vitro Whole Human Blood Impedance Aggregation Assay were used to study anti-platelet activity. Forty one plant extracts harvested from the tissues of 26 plants collected from Northern Thailand were assessed. Thirty-four plant extracts were found to have antibacterial activity against the Gram positive bacteria Staphylococcus aureus and/or Bacillus subtilis, while six plant extracts demonstrated activity against the Gram negative bacterium, Escherichia coli. Thirteen plant extracts exhibited anti-platelet aggregation activity better than the positive control. Two crude plant extracts, twigs from Garcinia sp. and twigs from Goniothalamus chilensis were selected for fractionation. Five of the 12 fractions showed anti-platelet activity. Four fractions (two from each plant extract) were selected for further sub-fractionation. Fourteen of 35 sub-fractions were selected for further testing of anti-platelet aggregation activity with 12 sub-fractions demonstrating positive antiplatelet activity. Positive sub-fractions were analyzed using liquid chromatography-mass spectrometry to determine their chemical properties. Three compounds that possessed anti-platelet activity were characterized by …
Date: May 2019
Creator: Patcharapinyopong, Thanasan
System: The UNT Digital Library

The Metabolic Physiology of Planarian Flatworms

Access: Use of this item is restricted to the UNT Community
Using a high throughput closed respirometry method to measure oxygen consumption, I determined metabolic rates in asexual and sexual Schmidtea mediterranea and Girardia dorotocephala, as a function of temperature, taxon, stressors, reproductive mode, age, regeneration, and specific dynamic action. This study has shown that oxygen consumption can reliably be measured in planaria using optode closed respirometry, and also provided a reliable method for measuring wet mass in planaria, which has been a challenge to researchers in the past. This research revealed that oxygen consumption in S. mediterranea is 1.5-2.1X greater in the sexual strain over the asexual strain at 13-18°C. Within the sexual strain, oxygen consumption is 1.5 -2.2X greater in sexually mature adults over the sexually immature groups (hatchlings, juveniles, and regenerating sexuals). Furthermore, I was able to quantify differences in sexual morphology between these groups exhibiting significant differences in oxygen consumption. The results of this research supports a theory of higher metabolic costs with sexual maturity in S. mediterranea. Therefore, this study has established sexual and asexual S. mediterranea as simple, yet attractive models for investigating energetic costs between sexual and asexual phenotypes. This research also provided quantitative values for specific dynamic action in planaria, with a maximum …
Date: August 2019
Creator: Lewallen, Melissa A
System: The UNT Digital Library

Ceramide Biosynthesis and NEET Proteins Impact Development, Function, and Maintenance of the Caenorhabditis elegans Germline

Access: Use of this item is restricted to the UNT Community
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 revealed that this pathway is essential for normal germline function in the aging adult hermaphrodite; specifically, precocious germline senescence was observed. Furthermore, I found that disruption of ceramide biosynthesis, via the hyl-2 deletion mutation, negatively impacts mAb15B4 localization at the P granules. Through genetic suppression analysis, I determined that insulin signaling and lipid biosynthesis can modulate the mAb15B4 localization to P granules. Additional, phenotype analysis showed that ceramide biosynthesis dysfunction decreased fecundity, and led to germline structure defects and uterine tumors. Through suppression analysis, I determined that modulation of the insulin signaling pathway suppressed the precocious germline senescence due to ceramide biosynthesis dysfunction. Since the presence of uterine tumors is associated with reproductive senescence I concluded that ceramide biosynthesis has a role in germline maintenance in the aging of the germline …
Date: August 2019
Creator: King, Skylar Dawn
System: The UNT Digital Library
Transgenerational Responses to Environmental Stressors in Vertebrates: From Organisms to Molecules (open access)

Transgenerational Responses to Environmental Stressors in Vertebrates: From Organisms to Molecules

Genomic modifications occur slowly across generations, whereas short-term epigenetic transgenerational inheritance of adaptive phenotypes may be immediately beneficial to large numbers of individuals, acting as a bridge for survival when adverse environments occur. In this study we used dietary exposure to crude oil as an example of an environmental stressor to assess its effects from the molecular to the organismal levels in piscine and avian animal models. In addition, we assessed the role of the parental exposures on their offspring F1 generation. The research developed in this dissertation has contributed to several areas of investigation including molecular biology, animal physiology, and evolutionary biology. The quantitative information from these studies may be utilized to supplement information regarding the proximate and ultimate effects of environmental stressors on fish and bird populations. Furthermore, this information may be used as additional support for understanding the conservation of the responses from the molecular to the whole organismal levels across the vertebrate taxa, as well as their implications for population survival and maintenance. Additionally, the zebrafish (Danio rerio), the Siamese fighting fish (Betta splendens) and the king quail (Coturnix chinensis) have proven to be excellent models to start building a strong basis for understanding the effects …
Date: December 2019
Creator: Martinez Bautista, Naim
System: The UNT Digital Library