Digital Commons Network^™

Investigating The Role Of Nuclear Foxo3 In Pten-Null Glioblastomas, Lilia Sanchez

Theses and Dissertations

The PI3K pathway activates AKT, leading to inactivation of FOXO transcription factors. Loss of PTEN results in constitutive inactivation of tumor suppressor FOXO. There is increasing evidence that FOXO resides and promotes transcriptional activity in the nucleus despite high PI3K output within certain advanced cancers and embryonic stem cells. Here, we investigate the regulation and roles of FOXO transcription factors in glioblastoma and basal breast cancer. First, we built and published genetic models to investigate the roles of FOXO transcription factors in cancer cell lines for glioblastoma (U87MG). We examined the function of FOXO transcription factors using these genetic models …

Trichomonas Vaginalis Cytoadherence Is Modulated By Oxidative Stress, Magali Ayala

Theses and Dissertations

The adherence of Trichomonas vaginalis to the human urogenital tract is a prerequisite for the pathogenesis of the infection. This multifactorial process is modulated by environmental factors such as iron, estrogen, temperature and pH and specific receptor/ligand interactions. During natural infections, the anaerobe T. vaginalis is exposed to oxygen resulting in oxidative stress. This environmental change may alter trichomonad cytoadherence to the ectocervical tissue. Therefore, it was hypothesized that changes in the redox status of T. vaginalis may modulate cytoadherence levels. Results showed that oxidative stress reduces levels of trichomonad cytoadherence to HeLa cells by > 50% when exposed to 150 …

A Phylogeographic Analysis Of Black Coral (Antipatharia) On Artificial And Natural Reefs In The Northwestern Gulf Of Mexico, Heather Otte

Theses and Dissertations

NOAA's Islands in the Stream concept (IitS) of designating networks of marine protected areas as refugia in the Gulf of Mexico depends on genetic connectivity. Isolated habitats like those proposed by the IitS occur naturally off the Texas coast where hard-bottom structures protrude from mudflats, offering a small-scale study of the IitS feasibility. Two sequences, mitochondrial 16S ribosomal RNA and nuclear internal transcribed spacer, were used to build haplotype networks of Antipatharians (Anthozoa: Hexacorallia), corals with planktonic larvae that can act as a proxy for connectivity of other organisms. Two species showed no significant genetic differentiation or pattern of genetic …

Regional Distribution, Non-Invasive Detection, And Genetic Diversity Of The Black-Spotted Newt (Notophthalmus Meridionalis), Evan A. Bare

Theses and Dissertations

The Black-spotted Newt (Notophthalmus meridionalis ) is one of three a salamander species native to Gulf Coast prairies of Texas and Mexico, with respective state and federal protections. This species has been neglected by the scientific community despite concerns of dramatic population declines and a globally endangered status, with the most recent work being conducted in the early 1990’s going unpublished. This study presents the most recent examination of the species providing probabilistic distribution maps, descriptions of three novel populations, assessments of surveying techniques, and the first known examination of intrapopulation genetics including the first documented genetic examination of …

Monitoring Wildlife Guards And Crossing Structures On A Divided Highway In South Texas, Tiffany C. Cogan

Theses and Dissertations

To mitigate ocelot (Leopardus pardalis albescens ) road mortality, Texas Department of Transportation installed fencing, wildlife road crossing structures (WRCS, n = 5), and wildlife guards (WG, n = 18) on divided State Highway 100 in Cameron County, Texas. During construction, active infrared (AIR, n = 24) and passive infrared (PIR, n = 24) cameras were side-by-side at WRCS (n = 6) and WG (n = 6). Community composition was significantly different (p = 0.0001) between camera types with AIR cameras detecting a more diverse and abundant community. Wildlife community was significantly different (p = 0.0002) between three WRCS …

Metabolic Dysregulation: An Investigation Of The Role Of Foxo3 In Gluconeogensis In Pten-Null Glioblastomas, Victor Fanniel

Theses and Dissertations

Many processes are regulated by the Phosphatidylinositol 3 kinase (PI3K) pathway in the cell including cell survival, metabolism, and apoptosis. Increased activation of the PI3K pathway is a hallmark of many cancers which can be oftentimes attributed to the mutation of PTEN, which encodes an enzyme that performs the reverse reaction of PI3K. When PTEN is null-mutated, this creates a constitutively active PI3K pathway and constitutively active AKT. Since AKT phosphorylates conserved residues on FOXO transcription factors to mark them for nuclear export, this renders FOXO inactive. However, new research has provided evidence that FOXO is still present in …

Progress And Potential Of Two Biological Control Agents Of The Invasive Giant Reed (Arundo Donax L.), Madeline Marshall

Theses and Dissertations

Biological control, or the use of natural enemies for pest management, may the best long-term option for managing the invasive Arundo donax , a noxious weed dominating riparian habitats globally and along the Rio Grande River. This work reports on the progress and potential of two arundo biological control agents permitted for release in Texas and Mexico. The arundo wasp, Tetramesa romana, released in 2009, is having significant impacts as reported from various field locations around the world, described here using standard exit hole counts. The highest density levels were found in Texas (introduced range) compared to relatively low …

Species Delimitation Among Southeastern Us Oxyloma (Gastropoda: Succineidae), Marco A. Martinez Cruz

Theses and Dissertations

The Succineid genus Oxyloma found throughout Canada and United States contains approximately 15 described species whose criterion for differentiation is considered unreliable. As a first step towards understanding the evolutionary history and revising the taxonomy of North American Oxyloma, we have sampled four species found in eastern North America (O. salleana, O. subeffusa, O. effusa, and O. retusa) from their type localities. We used mitochondrial COI, and nuclear LSU sequences with samples found across their range and members of the family to produce a phylogenetic hypothesis of evolutionary relationships and test species boundaries. Molecular phylogeny and species …

Functional Variation In The Mitochondrial Genome Of The Yeast Saccharomyces Cerevisiae, John F. Wolters

Graduate Dissertations and Theses

Mitochondrial haplotypes contribute to functional diversity in natural populations. Uniparental inheritance makes it difficult to characterize the genetic architecture of mitochondrially driven phenotypes. In this work I explored the natural diversity of mitochondrial genomes in the yeast Saccharomyces cerevisiae. Few complete mitochondrial genomes were available for S. cerevisiae owing to challenges in high-throughput sequencing. I developed sequencing strategies using new technologies to generate complete high quality yeast mitochondrial genomes. Comparisons of 100 complete yeast mitochondrial genomes demonstrated extensive variation between populations in coding sequences and variable introns.

I demonstrated that these mitochondrial variants directly caused growth differences in strains with …

Utilizing Accelerometer Telemetry Tags To Compare Red Snapper (Lutjanus Campechanus) Behavior On Artificial And Natural Reefs, Ethan T. Getz

Theses and Dissertations

The Texas Parks and Wildlife Department Artificial Reef Program has deployed over 2,800 hectares of reefing area composed of petroleum platforms, steel vessels, and concrete. Artificial reefs have been shown to support many important reef fishes such as red snapper (Lutjanus campechanus), however, few studies have compared fish behavior on artificial reefs and natural habitats. We examined activity levels, behavioral patterns and habitat preferences of red snapper over natural reefs, oil platforms and submerged ships. Telemetry tags (Sonotronics model MTT) with tri-axial acceleration range, average depth, and average temperature were programmed to optimize data collection and tag life. …

Genetic Diversity Of Kemp's Ridley (Lepidochelys Kempii) Sea Turtles On South Padre Island, Texas, Hilary R. Frandsen

Theses and Dissertations

In 2010, researchers observed an abrupt decline in nesting numbers of the Kemp’s ridley following 35 years of positive growth. In wake of this halt, and subsequent lowered nesting averages, evaluation of the genetic diversity of remaining individuals is relevant to investigate the plausibility of a genetic bottleneck, and determine the reproductive stability of the Kemp’s ridley.

Here, I evaluate the genetic diversity within a sampling of the Kemp’s ridleys on South Padre Island using two methods: targeting the mitochondrial control region and targeting the complete mitochondrial genome. Opportunistic samples were donated from juvenile ridleys on the East coast, and …

Phylogeography Of An Estuarian Calanoid Copepod; Acartia Tonsa In The Texas Gulf Of Mexico, Nicole J. Figueroa

Theses and Dissertations

The calanoid copepod, Acartia tonsa is one of the most abundant and well-studied estuarian species. However, the idea that this cosmopolitan species has unrestricted dispersal and high gene flow has been challenged. In this study, a more holistic picture of the phylogeography of A. tonsa was developed using the mitochondrial gene cytochrome oxidase one (mtCOI). Multiple new lineages were found in the Texas Gulf of Mexico that are basal to Northeastern Atlantic lineages. Connectivity was also observed between Brazil and the Texas Gulf of Mexico. The revised phylogeny shows a clear pattern of cryptic speciation as the species made a …

Effect Of Land Use Change On South Texas Bats, Katharine Leigh Jones

Theses and Dissertations

Bats were acoustically recorded in South Texas over the summer of 2017. Nine species of bats were recorded and identified.

Foxo3 Regulation Of Stem Cell Markers Oct4 And Sox2 In Pten-Null Glioblastomas, Eduardo Martinez

Theses and Dissertations

The PI3K pathway controls many cellular processes such as cell growth, survival, metabolism, apoptosis, and differentiation. Canonically, PI3K activates AKT leading to subsequent nuclear exportation of FOXO transcription factors. Dysregulation of the PI3K pathway is a hallmark in many cancers and often is attributable to a null mutation in PTEN. PTEN is a phosphatase that reverses the reactions catalyzed by PI3K. Loss of PTEN leads to constitutive inactivation of tumor suppressor FOXO proteins. However, there is increasing evidence that FOXO may still reside and promote transcriptional activity in the nucleus despite high PI3K output within certain advance cancers and …

Effectiveness Of The Flipped Classroom Model In Anatomy And Physiology Laboratory Courses At A Hispanic Serving Institution, Gerardo Sanchez

Theses and Dissertations

A flipped laboratory model involves significant preparation by the students on lab material prior to entry to the laboratory. This allows laboratory time to be focused on active learning through experiments. The aim of this study was to observe changes in student performance through the transition from a traditional laboratory format, to a flipped format. The data showed that for both Anatomy and Physiology (I and II) laboratories a more normal distribution of grades was observed once labs were flipped and lecture grade averages increased. Chi square and analysis of variance tests showed grade changes to a statistically significant degree, …

Central Precocious Puberty Alters The Mammary Gland Epithelial Landscape In Female Rats, Alina M. Hamilton

Theses and Dissertations

Precocious puberty (PP) is a serious endocrine disorder associated with an increased risk for development of breast cancer (BC) later in life. However, the lack of a strong in vivo model has made it difficult to study this relationship. Our group has established manganese (Mn) as a non-toxic activator of the pubertal process. Recently we demonstrated that Mn-induced precocious puberty (MnPP) accelerates E2-regulated mammary gland (MG) development in prepubertal female rats, resulting in persistent proliferation and adult hyperplasia. Using this model, I demonstrate that precocious puberty alters steroidal regulation of proliferation in both the prepubertal and adult virgin MG, altering …

Oxidative Insults Disrupt Mitochondrial Dynamics, Iraselia A. Garcia

Theses and Dissertations

Mitochondria form an organellar network to provide ATP to the cell. Mitochondrial DNA (mtDNA) combines with nuclear DNA to encode polypeptides critical to forming the complexes of oxidative phosphorylation in the mitochondrial inner membrane, which generate a transmembrane potential (ΔΨm) to synthesize ATP. This ΔΨm is required to maintain mitochondria fission/fusion dynamics: organellar fusion (mediated by OPA1) and fission events (mediated by DRP1) coordinately regulate mitochondrial dynamics. While oxidative stress correlates with mitochondrial dysfunction, it is unclear how oxidants affect mitochondrial structure/function homeostasis. This project seeks to establish and examine the impact of reactive oxygen species (ROS) on mitochondrial dynamics. …

Economic Assessment Of A Highly Pathogenic Avian Influenza Outbreak In Washington And Benton Counties In Arkansas, Antonio Beitia

Graduate Theses and Dissertations

Highly Pathogenic Avian Influenza (HPAI) presents a substantial economic risk to the poultry industry. Domesticated fowl contract HPAI initially through exposure, direct or indirect with migratory waterfowl and outbreaks can result in significant economic losses to growers and the poultry industry at large. A HPAI outbreak occurred in Minnesota and Iowa and spread across over 13 other states in 2014 and 2015. This caused an estimated $1.6 billion in losses (CDC, 2016) and led to shortages of eggs and turkeys together with elevated prices (Anni et al. 2005). Even small outbreaks of HPAI inflict substantial damages as USDA-APHIS guidelines necessitate …

Evaluation Of The Correlation Between The Oxidation Reduction Potential And Free Chlorine Residual For Different Chlorine Sources Used In Poultry Drinking Water Sanitation, Samantha Renee Cox

Graduate Theses and Dissertations

A critical component in commercial poultry production is to ensure birds are provided clean, quality water. Multiple disinfectants can be utilized to optimize a good water quality program. The goal of these water disinfectants is to greatly reduce or eliminate the presence of all bacteria. In recent years, the oxidation-reduction potential (ORP) meter has been a tool utilized by the poultry industry to monitor chlorine efficacy in drinking water. An ORP reading of 650-750 millivolts (mV) has become the industry standard for assuring an acceptable sanitizing residual of free chlorine is present for controlling microbial contamination regardless of the actual …

Refusing To Be Dispossessed: African American Land Retention In The Us South From Reconstruction To World War Ii, Camille Goldmon

Graduate Theses and Dissertations

African Americans in the South were tied to the land during slavery and after emancipation. Many felt that land ownership was the key to freedom. For decades, black farmers strove for land ownership, in many cases falling prey to sharecropping and tenancy agreements in the meantime. Despite this drive toward independent farming, however, since 1920, there has been a steady decline in the number of black farm owners. This trend is especially prevalent in the Southern United States. The black farm owners who persevered through periods of economic, social, and political turmoil were able to, for varying reasons, navigate those …

Environmental And Climatic Constraints On Large-Scale Camelina Production In Eastern Arkansas, Benjamin Robert Tracy

Graduate Theses and Dissertations

Camelina sativa is a cold weather crop that is typically grown in semi-arid environments in the Western United States, usually as a spring crop, but sometimes during the winter. Research analyzing climate data and soil hydrology is important to better understand the environmental and terrain conditions necessary for Camelina farming wherever it is proposed for large-scale production. This study focused on various conditions and constraints pertaining to the potential for Camelina as a crop biofuel in Eastern Arkansas. Due to interest in the economic potential of crop biofuels in this area, and in particular the low input costs for Camelina, …

Central Role Of Vasotocin In The Neuroendocrine Regulation Of Stress Responses And Food Intake In Chickens, Gallus Gallus, Gurueswar Nagarajan

Graduate Theses and Dissertations

It is well known that arginine vasotocin (AVT) in birds is involved in physiological homeostasis such as cardiovascular, osmotic regulation as well as reproductive functions. Pertinent to these physiological functions, AVT immunoreactive (-ir) neurons in the hypothalamus have been found associated with hemorrhage, dehydration, oviposition and other physiological regulation. Evidence, however, suggests that AVT also plays significant roles in modulating behavior, memory, stress, and food intake. This dissertation research addresses the latter two neuroendocrine functions of AVT in detail within the chicken brain. First, the functional role of AVT-ir neurons in conjunction with corticotropin releasing hormone (CRH)-ir neurons in the …

Influence Of Histidine Residues, Ph And Charge Interactions On Membrane-Spanning Peptides, Ashley N. Henderson

Graduate Theses and Dissertations

Designed transmembrane peptides were employed for investigations of histidine residues within the hydrophobic environment of the lipid bilayer by means of oriented solid-state deuterium NMR spectroscopy. Using the model peptide GWALP23 sequence (GGALW(LA)6LWLAGA) as a host framework, the effects of single and double histidine mutations were explored. Replacement of leucine residue 12 to polar neutral histidine had little influence on the peptide average orientation, however under strongly acidic pH conditions in DOPC bilayers, the histidine becomes positively charged (pKa 2.5) and the GWALP23-H12 peptide exits the membrane and adopts a surface-bound orientation. Conversely, mutation of leucine 14 to neutral histidine …

Temporal Evaluation Of Corn Respiration Rates Using Pressure Sensors, Gagandeep Singh Ubhi

Graduate Theses and Dissertations

High respiration rate of a grain indicates faster degradation of its dry matter. Proper grain management requires chronological and precise measurements of carbon dioxide evolved from grain respiration during the postharvest storage duration. Therefore the main goal of this research was to develop a new technique that evaluates temporal corn respiration rate using pressure sensors. It was based on measuring pressure drop associated with the grain respiration in a closed container and using it to calculate the grain respiration rates.

Dry corn (Zea Mays L.) was procured from a local farmer and stored at 4ºC. Corn rewetting technique was applied …

Influence Of Stream Permanence, Predation, And Invasive Species On Crayfish In The Ozark Highlands With An Emphasis On Species Of Greatest Conservation Need (Orconectes Marchandi, Orconectes Eupunctus And Cambarus Hubbsi), Allyson Noelle Yarra

Graduate Theses and Dissertations

Due to the ecological importance of crayfish and the increasing vulnerability of freshwater systems due to habitat loss, invasive species, and hydrologic alteration, understanding crayfish-environment relationships is crucial in the context of aquatic species conservation. I sought to examine the influence of hydrologic variation among intermittent and permanent streams on crayfish occupancy, abundance, predation risk, and potential vulnerability to invasive species effects. I conducted crayfish and environmental data sampling during two consecutive summers across 20 Ozark streams of differing permanence levels (10 intermittent, 10 permanent). In these same streams, I conducted fish and scat surveys over the course of four …

Flight Activity, Oviposition Pit Distribution, And Emergence Densities Of Monochamus Titillator And M. Carolinensis In The Ozark-St. Francis National Forest In Arkansas, Jake Bodart

Graduate Theses and Dissertations

Monochamus (Coleoptera: Cerambycidae) are a genus of longhorn beetles commonly known as pine sawyers. They have a worldwide distribution coincident with pines (Pinaceae) and are vectors of the pinewood nematode (Bursaphelenchus xylophilus). In the United States, there are eight known Monochamus species and they have a sympatric distribution with at least one other Monochamus species throughout their range. Monochamus are known to attack stressed, dead, and dying conifers especially pines. In the Ozark- St. Francis National Forest in Arkansas, there are two species of pine sawyers and they share this sympatric distribution observed throughout the United States, M. titillator (southern …

Characterization Of The Rnap Binding Sites On A Λ Dna Using A Solid State Nanopore Combined With A Tuning Fork Force Sensing Probe Tip, Harpreet Kaur

Graduate Theses and Dissertations

In this dissertation, the binding positions of RNAP holoenzyme on a λ DNA are characterized using an apparatus that integrates a Solid State Nanopore with a Tuning Fork based Force sensing probe (SSN-TFFSP). The SSN-TFFSP system combines the measurement of ionic current through a solid-state nanopore with a DNA tethered probe tip. The position of the tip is sensed by a tuning fork force sensor and is controlled with a nanopositioning system. With this apparatus, translocation speed of DNA through solid state nanopores has been brought down to 100 μs/base. Such a controlled movement of DNA through a solid state …

Using Rb-Tnseq To Analyze Natural Variation In Saccharomyces Cerevisiae, Syed Raza Mahmood

Graduate Theses and Dissertations

One of the main challenges in biology today is the characterization of millions of genes of unknown function being continuously identified in sequencing studies. Transposon mutagenesis is a technique that has been widely used for annotating gene function and has now been combined with next-generation sequencing (Tn-Seq) to assess mutant fitness on a genome wide basis. However, Tn-Seq approaches are often constrained by laborious library preparation protocols which limit the number of organisms or conditions that can be assessed. Random bar code transposon-site sequencing (RB-TnSeq), is a transposon sequencing technique that streamlines library preparation and increases the throughput of mutant …

Thylakoid Protein Targeting/Insertion By A Signal Recognition Particle In Chloroplasts, Priyanka Sharma

Graduate Theses and Dissertations

Protein targeting is a fundamental cellular process that directs proteins from their site of synthesis to the site where they function. The signal recognition particle (SRP) dependent targeting pathway is conserved in both eukaryotes and prokaryotes where it co-translationally targets polypeptide chains emerging from ribosomes to the endoplasmic reticulum (eukaryotes) or cytoplasmic membrane (prokaryotes). A structurally unique form of SRP is found in chloroplasts where it functions to post-translationally bind and target a subset of integral thylakoid membrane proteins, the light harvesting chlorophyll binding proteins (LHCPs). Mature LHCPs bind chlorophyll a/b and function in photosynthetic light capture. Like many other …

Development Of A One Pass Microwave Heating Technology For Rice Drying And Decontamination, Deandrae Lynette Smith

Graduate Theses and Dissertations

An industrial microwave (MW) system operating at 915 MHz frequency was used to dry high moisture content (MC) (23% to 24% wet basis) medium-grain rough rice samples (cv. Jupiter). The rice beds were contained in a modified tray that accommodated up to 9 kg of rice separated by thin fiberglass mesh in 3 kg increments. Each layer of rice was fitted with fiber optic sensors connected to a real time data logger during MW treatments. It was determined that drying rice to a MC of 14% to 16% was feasible with the application of MW specific energy at 600 kJ/kg-grain …