Biology Commons^™

Questing Activity Of Cattle Fever Tick Larvae, Rhipicephalus (Boophilus) Microplus (Acari: Ixodidae): Environmental Influences And Implications For Control In South Texas, Brenda Leal

Theses and Dissertations

Questing ticks ascend stems, leaves, or rocks, extend their front legs, and wait poised for attachment to a passing host. Ixodid ticks have four developmental stages. Because ticks detach and molt between stages most ticks require three separate hosts to complete their lifecycle. Three-host ticks quest for a new host between each stage, whereas a few specialist tick species remain on and thus require only a single host. These one-host ticks only quest for hosts as larvae. As much as 90% of the life cycle may consist of questing when hosts are scarce. Most of the literature on questing relates …

Environmental Conditions In San Martin Lake: Effects Of Eutrophication In An Estuary Associated With The Laguna Madre, Wendy L. Rogers

Theses and Dissertations

San Martin Lake is a shallow water Estuary in the lower Laguna Madre off the Port of Brownsville Shipping channel. It is influenced both by incoming tides and waste water runoff both from local farms and the Brownsville water treatment plants. The resulting mixture of eutrophic water and incoming sea water creates the perfect mix for a potential algal bloom. This study looks at the nutrient levels and environmental conditions in the main basin of the estuary to establish baseline levels and to observe the rate of nutrient clearing being accomplished in this environment. As sport recreation in the area …

Survey Assessment Of Community Knowledge And Prevention Of Chagas Disease And Its Vector In Hidalgo And Cameron Counties, Adam Dennis Wiejaczka

Theses and Dissertations

Chagas disease, caused by the parasite Trypanosoma cruzi, kills thousands of people annually and is the dominant cause of infectious myocarditis worldwide. Kissing bugs are vectors that carry T. cruzi . and are found in the Lower Rio Grande Valley (LRGV). There is no vaccination nor cure for Chagas. The best mechanism of prevention is to control vector infestations. Little research is available regarding the level of understanding local communities have about Chagas.

Our goal was to test the knowledge of several communities in the LRGV on Chagas disease. Our hypothesis states that local communities do not have sufficient …

Embryology And Wing Development In A Dragonfly (Tramea Onusta), Valeria M. Casas

Theses and Dissertations

Most phylogenetic research within the insect phylogeny is focused on higher order taxons. Therefore, to better understand insect wing and flight origin, genetic studies on more primitive insect orders is necessary. Odonata, the order including dragonflies, is one of the earliest insect taxa to develop wings. Hox genes are highly conserved regulatory genes involved in embryonic development of organisms. Hox gene expression studies in insects allow improved insight of body plan development including wings. Embryonic development of dragonfly, Tramea onusta, was analyzed at various developmental stages. Developmental genes Antennapedia, Distal-less, Ultrabithorax, abdominal-A, Abdominal-B, engrailed, Cadual, engrailed 2, Wingless, nubbin, …

Nannochloris Sp. And Oocystis Sp. Algae Exposed To Osmotic Stress For Increased Lipid Production For Use In Biofuels, Laura M. Chavez

Theses and Dissertations

Algal biofuel research is important due to the potential need for replacement of non-renewable fossil fuels and a changing global climate. Under stress, algal cells tend to increase neutral lipid production, which are a suitable source for biofuels. The goal of this study was to subject Nannochloris sp.. and Oocystis sp. algal cells to osmotic stress by modifying sucrose and salinity levels in different treatment medias.

The treatment containing the lowest salinity (15 ppt) and no sucrose yielded the highest lipid fluorescence/cell in Nannochloris sp.. cells (0.00142 ± 0.00044) on day 2 while the treatment containing highest salinity (35ppt) …

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 …

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 …

Genetic Basis For Elevated Rheumatic Heart Disease Susceptibility In Samoa, John Bowen Allen

Theses and Dissertations

Rheumatic heart disease is an inflammatory heart disease that affects millions of people around the world. Especially high rates of the disease can be found in Oceania, including the island nation of Samoa. Genetic studies of immune response genes have provided insight into a possible genetic link to increased susceptibility to rheumatic heart disease, including the genes that code for the toll-like receptor (TLR) protein family. One of the functions of TLR proteins is to recognize the presence of bacteria via identification of bacterial flagella. My evaluation of a Samoan family identified a variant in the TLR-5 gene that would …

Morphology Of The Olfactory Apparatus In Leptocephalus Larvae, Molly Ann Wightman

Theses and Dissertations

Leptocephalus larvae are a unique larval form that unites the Elopomorph fishes. This larval form has morphological and cellular characteristics that differ from most other teleost fishes. The visual system of leptocephali rod-dominated retinas, leading to poor photopic vision and low visual acuity that would hinder feeding on planktonic prey. Recent studies indicate they feed marine snow, which is composed of mucilaginous materials, bacteria and plankton. Their low visual acuity raises the question of how these organisms find this gelatinous food source in the wild. I hypothesize that these larval fishes use chemoreception in order to find marine snow, and …

Smelling Weakness: Mechanical Damage Influences The Volatile Emissions Of Prunus Bark, Matthew Hetherington

Theses and Dissertations

Volatile organic compounds (VOCs) emitted from plants often mediate interactions with constituents of the broader ecosystem. In this study I examined the extent to which VOCs emitted from the bark of Prunus species change after mechanical wounding, and thereby influence the behavior of Sesiid peach pests. This research represents the first application of solid-phase microextraction to the characterization of Prunus bark volatiles and the first investigation of bark emissions as mediators of Sesiid behavior in three decades. I document significant decreases in benzaldehyde emission coinciding with increases in benzyl cyanide, p-cymene, linalool, and camphene after wounding in both Prunus species …

Biotic Filtering In Endophytic Fungal Communities, Kevin Daniel Ricks

Theses and Dissertations

Plants can be colonized by complex communities of endophytic fungi. This thesis presents two studies, both of which investigate biotic filtering in endophytic fungal communities. Chapter 1. Endophytic fungi can be acquired horizontally via propagules produced in the environment such as in plant litters of various species. Given that litters from different plant species harbor distinct endophytic fungal communities and that endophytic fungi may be dispersal-limited, the structure of the endophytic fungal community of a given plant may be determined by proximity to particular inoculum sources. Community assembly may also be affected by biotic filtering by the plant. Therefore, a …

Determining The Relationship Between Aging And Oxidative Stress In A Drosophila Melanogaster P38 Kb Framework, Aleksandra J. Majewski

Theses and Dissertations

Aging is inevitable for all organisms and can be characterized by degeneration of tissue, adecrease in motor function, and impaired stress response. In humans, it is often accompanied by an increased propensity for age related diseases. While all adults experience biological aging (senescence) not all adults experience age-associated disease. Thus, we claim these are not normal prospects of aging. Although the implications of aging are well understood, the molecular underpinnings for these processes remain elusive. As advances in medical science have been successful at prolonging lifespan, they concurrently extend the amount of time spend in diseased states. If we wish …

Studies On Inositol Polyphosphate-Mediated Cell Death Process In Dictyostelium Discoideum And Its Sensitivity To Single-Walled Carbon Nanotubes, Qudes Ali Al-Anbaky

Theses and Dissertations

Inositol polyphosphates (InsPs) are naturally occurring compounds that are widely distributed in both plant and animal cells. They regulate a variety of cellular processes including programmed cell death or apoptosis. Apoptosis maintains tissue homeostasis in higher organisms. Among inositol polyphosphates, inositolhexakisphosphate was found to be the most potent inducer of apoptosis in mammalian cells, however, the mechanism of apoptosis particularly mediated by InsPs is not well understood in simple eukaryotes such as Dictyostelium discoideum, despite InsPs having been well studied in this model organism. MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide, LDH, and trypan blue assays were used to investigate the cytotoxic …

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 …

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 …

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 …

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 …

Identification Of Elements Essential For Replication Origin Activity In Escherichia Coli, Prassanna Rao

Theses and Dissertations

The increasing number of drug resistant pathogenic bacteria has created a growing health care crisis. Solving the crisis will require a number of solutions, among them being development of new antibiotics that target novel cell processes. Initiation of chromosomal DNA replication is one such unexploited process. Bacterial cells begin chromosome replication by building a nucleoprotein complex called the orisome which, unwinds replication origin DNA, and loads the replicative helicase. A greater understanding of how orisomes assemble, and how the assembly is regulated, should provide a source of druggable targets to be used in future antibiotic discovery efforts. However, although all …

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 …

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 …

The Effect Of Anthropogenic Activity On Sea Turtle Nesting And Habitat Usage In Florida, Usa, Raschelli Anna-Elizabeth Linz

Theses and Dissertations

Sea turtles have complex life histories that make them difficult to study. Using easily-accessible data, such as nesting and stranding occurrences, can help to efficiently elucidate driving factors in the population dynamics of these imperiled species. The overall goal of the present study was to assess the efficacy of sea turtle protective measures in Florida. To accomplish this goal, two analyses were conducted. The first analysis sought to describe the relationship between nesting numbers of three species of marine turtles, the loggerhead (Caretta caretta), green (Chelonia mydas), and leatherback (Dermochelys coriacea), common in Florida and various anthropogenic and environmental variables. …

Spectral Sensitivity Of The Invasive Lionfish (Pterois Species) Retina And Its Capacity For Change In Response To Lighting Condition, Miranda Roseland Carroll

Theses and Dissertations

Since their first confirmed sighting in 1985 in the tropical western Atlantic, invasive lionfish of the genus Pterois have had a detrimental impact on marine systems in this region, including significant declines in native reef-fish populations. The environmental tolerances of these predators are very broad, allowing them to inhabit a variety of environments: they can withstand large ranges of depths, salinities, and temperatures. Understanding their physiological and behavioral characteristics can provide insight for the success of these invaders. Adaptable visual capabilities is one biological characteristic that may assist their invasive success. I hypothesized that lionfish possess retinal plasticity and can …

Small Mammal Diversity, Rattlesnake Demographics, And Resource Utilization In The Great Basin: Implications For Management And Stable Isotope Proxies, Bryan T. Hamilton

Theses and Dissertations

Plant carbon isotopes were used to track assimilation of riparian resources by small mammals. Voles and shrews derived significant portions of their carbon from riparian vegetation. Deer and harvest mice were abundant in riparian habitat but assimilated little riparian vegetation indicating that the riparian corridor provided resources other than food. This is first use of stable carbon isotopes to trace riparian resources into a vertebrate community. Conifer encroachment in sagebrush ecosystems negatively affects many wildlife populations. Conifer removal is recommended across millions of hectares in the Great Basin. However the effects of conifer encroachment and conifer removal are unknown for …

Analysis Of Whole Exome Sequence Data In Affected Cousin Pairs From High-Risk Alzheimer's Pedigrees, Lyndsay Ann Staley

Theses and Dissertations

Genetic factors account for about half of Alzheimers Disease (AD) risk and only about a quarter of that heritability is accounted for by known variants. Family based approaches to understanding AD genetics may be an effective way to identify additional risk factors. Here we report the results of whole exome sequencing (WES) and analyses done on pairs of AD affected cousins from 19 families from the Utah Population Database (UPDB) with a statistical excess of AD risk. WES variants passing quality control were additionally filtered by population frequency (minor allele <<> 0.01) and concordance between cousin pairs, resulting in 564 variants …

The Evolutionary Significance Of Body Size In Burying Beetles, Ashlee Nichole Momcilovich

Theses and Dissertations

Body size is one of the most commonly studied traits of an organism, which is largely due to its direct correlation with fitness, life history strategy, and physiology of the organism. Patterns of body size distribution are also often studied. The distribution of body size within species is looked at for suggestions of differential mating strategies or niche variation among ontogenetic development. Patterns are also examined among species to determine the effects of competition, environmental factors, and phylogenetic inertia. Finally, the distribution of body size across the geographic range of a species or group of closely related is looked at …

Analysis Of A Functional Heterologous Chromosomal Replication Origin Transplant In E. Coli, Rohit Pradip Kadam

Theses and Dissertations

To ensure that all cells replicate their genomes faithfully before they divide, the initiation step of chromosome replication must be tightly regulated during the cell cycle. In bacteria, new rounds of replication are triggered by the assembly of a higher order protein complex, termed the orisome, that unwinds a well-defined origin (oriC) region on the circular chromosome, and prepares it for new replication forks. Orisomes comprise multiple copies of a highly conserved initiator protein, DnaA, and instructions for ordered orisome assembly are encoded into the oriC nucleotide sequence of nearly all bacteria as specifically-spaced clusters of 9 base pair (bp) …

A Combinatorial Premotor Neural Code: Transformation Of Sensory Information Into Meaningful Rhythmic Motor Output By A Network Of Heterogeneous Modulatory Neurons, Christopher John Goldsmith

Theses and Dissertations

The goal of the following research was to investigate the contributions of neural networks in selecting distinct variants of rhythmic motor activity. We used the premotor commissural ganglion (CoG) in the stomatogastric nervous system of the Jonah crab to understand how this network effectively controls the rhythms produced in downstream motor circuits. Prior research determined that individual CoG neurons are necessary to mediate sensory-induced variation in the effected motor patterns. However, single premotor neuron inputs to the STG are not sufficient to recreate the patterns induced by the selective activation of sensory pathways. Thus, it was hypothesized that the CoG-mediated …

Molecular Evolution Of Odonata Opsins, Odonata Phylogenomics And Detection Of False Positive Sequence Homology Using Machine Learning, Anton Suvorov

Theses and Dissertations

My dissertation comprises three related topics of evolutionary and computational biology, which correspond to the three Chapters. Chapter 1 focuses on tempo and mode of evolution in visual genes, namely opsins, via duplication events and subsequent molecular adaptation in Odonata (dragonflies and damselflies). Gene duplication plays a central role in adaptation to novel environments by providing new genetic material for functional divergence and evolution of biological complexity. Odonata have the largest opsin repertoire of any insect currently known. In particular our results suggest that both the blue sensitive (BS) and long-wave sensitive (LWS) opsin classes were subjected to strong positive …

Learning And Behavior In Hatchling Trachemys Scripta Exposed To Bisphenol-A During Embryonic Development, Justin E. Dillard

Theses and Dissertations

Steroids play an integral role in orchestrating embryonic development, and can affect a suite of phenotypic traits, including learning and memory. Endocrine disrupting compounds (EDCs) can mimic the effects of steroids and can affect the same suites of phenotypic traits during embryonic development. Bisphenol-A (BPA) is an EDC that mimics the action of estrogen, and recent work is beginning to implicate BPA in effects on learning and behavior similar to those caused by estrogen treatment studies. Red-eared slider turtles (Trachemys scripta) are a good system to investigate the effects of BPA on learning and behavior, both because the molecular underpinnings …

How The Egg Rolls: A Morphological Analysis Of Egg Shape In The Context Of Displacement Dynamics, Ian R. Hays

Theses and Dissertations

Very little is known about how morphology effects the motion, stability and the resulting viability of avian eggs. The limited research that exists focuses on the pyriform or ‘pointed’ egg shapes found in the Alcidea family. This unusual shell form is thought to suppress displacement and prevents egg loss on the cliffside nesting habitat of the Uria genera. Unfortunately, these studies never isolated or quantify the specific morphological features (elongation, asymmetry and conicality) of these pyriform eggs, which limits their applicability to other taxa and hampers a robust proof of concept. We isolated each feature as a variable, produced models …