Biology Commons^™

Water Clarity At The River-Estuary Transition Zone: A Comparative Study Of The James, Mattaponi, And Pamunkey Sub-Estuaries, Rachel Henderson

Theses and Dissertations

Water clarity is a key parameter for monitoring water quality and often used to assess habitat suitability for submerged aquatic vegetation (SAV). Light attenuation, a measure of water clarity, is impacted by colored dissolved organic matter (CDOM), and by suspended particulates which include living and non-living components. We anticipated that the relative importance of these factors in regulating light attenuation would vary among the upper portions of three sub-estuaries differing in morphometry, hydrology, and degree of human influence. The James is characterized by eutrophic conditions and high algal abundance, whereas the Mattaponi and Pamunkey exhibit lower phytoplankton production. The Mattaponi …

Searching For Gold: Using A Novel Land Cover Classification To Identify Multiscale Drivers Of Site Occupancy By A Flagship Species For Early-Successional Habitat Conservation, Baron Lin

Theses and Dissertations

Understanding habitat selection at multiple scales is an important step in guiding conservation programs and reversing species declines. This, however, is difficult for species that occupy early-successional habitats (ESH) due to a lack of accurate representation of shrub cover in publicly available land cover data. The Golden-winged Warbler (Vermivora chrysoptera; GWWA) is a threatened species of conservation concern and a flagship for ESH conservation. We used a novel, LIDAR-derived land cover classification that accurately identifies shrubs at a fine resolution (1m) to investigate how habitat composition and configuration influence GWWA site occupancy. We aggregated this same land cover …

Validating The Methods And Assays Necessary For Establishing An Effective In Vitro Lung Cancer Transformation Model, Crystal Turner

Theses and Dissertations

In my research, I developed tools and performed assays to study the in vitro transformation of immortalized lung epithelial cells by oncogenic KRAS^G12V. I delivered the KRAS by transfection and lentiviral transduction, and after confirming the cells expressed KRAS, I evaluated transformation using several experimental approaches including monitoring of EMT markers and various types of growth assays. I also conducted preliminary experiments that quantified sphingolipid alterations in the cells that had markers indicative of having gone through EMT. The goal of these experiments was to assess whether sphingolipids are altered in cells that are transformed in vitro by …

Impact Of Targeting Glycosylated Ceramides On Tumorigenic Properties, And Characterization Of Sphingolipids In Head And Neck Tumors, Katherine E. Hylton

Theses and Dissertations

Sphingolipids play a crucial role in signaling, membrane structure, and migration, making them important molecules in cancer development, metastasis, and drug resistance. While some sphingolipids have been associated with pro-apoptotic or pro-survival behaviors, the role of many sphingolipids in cancer remains poorly defined. Chapter 1 of this study investigated the impact of three enzymes that compose most of the ceramide to Lc3 ceramide pathway – UGCG, GBA, and B3GNT5 – and how their alteration impacts chemoresistance and basal membrane invasion in vitro. It was found that the CΒE-induced inhibition of GBA, which converts glucosylceramide to ceramide, has no effects on …

Modeling Vegetation Effects On Barrier Island Evolution, Eric W. Schoen

Theses and Dissertations

Barrier islands play a significant role in protecting coastlines and harboring coastal habitats. In an effort to study and better understand the evolution of barrier island systems, a cellular model capturing various meteorological and environmental processes is proposed. Erosion due to wind, gravity, and marine processes are coupled with plant population effects. We demonstrate the inhibition of plant cover on sediment mobility, island migration, and erosion in the presence of sea level rise.

The Mechanisms And Consequences Of Shrub Encroachment On The Virginia Barrier Islands, Lauren K. Wood

Theses and Dissertations

Shrub encroachment is a global phenomenon driven by direct and indirect anthropogenic influence which alters plant communities and ecosystem function. Many studies have investigated drivers and consequences of woody plant establishment, but mesic landscapes are underrepresented in the literature. My objective was to assess the mechanisms of Morella cerifera encroachment into coastal mesic grassland, the potential for self-reinforcement, and consequences on community composition, nutrients, and landscape productivity. I studied temperature and water microclimate modification by Morella cerifera presence and removal to understand ecosystem engineering and community composition changes. Additionally, I examined the influence of shrubs on surrounding grassland species traits …

Detecting Snake Fungal Disease (Ophidiomyces Ophiodiicola) In The Lower Rio Grande Valley, Manuel Zavala

Theses and Dissertations

Emerging diseases such as Snake Fungal Disease (SFD) caused by the fungus Ophidiomyces ophiodiicola (Oo) have caused population declines in various snake species in the United States which play a crucial role in the ecosystem as a natural pest control. This fungus targets the scales as a medium to thrive on which can lead to facial disfiguration and respiratory infections. We examined snakes to see if SFD was present in the LRGV and if other fungal species pose a threat to the various snake species population. The data for this study consisted of 14 live snakes captured in …

Discerning Competitive Vs. Facilitative Relationships Of Weeds On Forest Restoration Efforts At La Sal Del Rey, Tx, Mylen A. Arias

Theses and Dissertations

Dryland ecosystems need effective restoration strategies to address severe degradation. It is often assumed that voluntary forb weeds either compete with or have no effect on native seedlings. In contrast, theory and empirical work suggest a potential facilitative role for such forb weeds. We conducted a manipulative weed exclusion experiment at a semi-arid site in South Texas targeted for large scale forest restoration and subsequently dominated by early successional forb weeds to discern the net effect of these weeds on the growth and survival of target thornscrub tree and shrub seedlings. Overall, weed presence did not significantly affect seedling mortality …

Developing Methods To Survey, Collect, Process, And Screen Endemic Entomopathogenic Fungi Against The Asian Citrus Psyllid In The Lower Rio Grande Valley, Jonathan Cisneros

Theses and Dissertations

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), vectors “Candidatus Liberibacter spp.”, the causative agent of Citrus Greening Disease. Managing ACP is imperative given the continuous increase in HLB positive trees. An aspect of integrated pest management (IPM) is the use of entomopathogenic fungi for the biological control of D. citri.

In order to identify endemic entomopathogenic fungi actively infecting D. citri, ACP were collected from local residential areas, surface sterilized, and plated on a semi-selective agar medium. Collection of over 9,300 samples from 278 sites throughout the LRGV led to the positive identification of …

Disturbance, Defense And Fitness In Silverleaf Nightshade (Solanum Elaeagnifolium) In Their Native Range In South Texas, Jesus Chavana

Theses and Dissertations

The role of human disturbance in accelerating weed growth is well understood. While most of these studies have focused on soil mediated disturbance, mowing is also a management practice that could impact weed traits. Using silver leaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, we asked whether continuous mowing affects growth and plant defense traits. We found that mowed plants produced significantly less fruits, had lower total seed fitness, but had higher seed mass, and germinated significantly faster. When three common herbivores were allowed to feed on the seedlings; tobacco hornworm (Manduca sexta), a generalist Solanaceae caterpillar gained more …

Interactive Effects Of Heat Stress And Pesticides Co-Exposure On Swimming Behavior, Oxidative Stress, Antioxidant Expression, And Redox Status In Common Goldfish (Carassius Auratus), Brittney Danielle Lacy

Theses and Dissertations

Aquatic ecosystems are inundated by environmental pesticides. This study, observed the dose-dependent effects of pesticides cocktail (metalachlor, linuron, isoproturon, tebucanazole, aclonifen, atrazine, pendimethalin, and azinphos-methyl) and elevated temperature (32 °C for 4-week exposure) on morphology of gills and kidneys, and expression of nitrotyrosine protein (NTP), dinitrophenyl protein (DNP), catalase (CAT), superoxidase dismutase (SOD), Na+/K+-ATPase, renin, and apoptosis in tissues of goldfish. Additionally, the effects on the free-swimming behavior were also observed. Histological analysis showed wide-spread damage in tissues at higher temperature and pesticides co-exposure. Immunohistochemical analysis demonstrated alterations in NTP, DNP, CAT and SOD expressions in tissues at higher temperature …

Role Of Glycolytic Metabolism In Glioblastoma Multiforme, Shreya Udawant

Theses and Dissertations

PI3K/AKT/mTOR signaling pathway is activated in 90% of all Glioblastoma Multiforme (GBM) tumors. We used a dual targeting approach to interfere with the phosphoinositide 3-kinase- mammalian target of rapamycin (PI3K-mTOR) pathway by treating U87MG GBM cells with NVP-BEZ235 (PI3K and mTOR a dual inhibitor) and, their downstream effects on molecular regulation on glycolytic genes were investigated using RNA-sequencing and gene set enrichment analysis (GSEA). RNA-seq identified 7803 differentially regulated genes in response to NVP-BEZ235. GSEA identified two glycolysis-related gene sets had significant differences (P < 0.05) in gene expression between control and NVP-BEZ235 treated samples. The GSEA core enrichment reported 17 and 35 genes were significantly downregulated (P adj < 0.05) in response to NVP-BEZ235 treatment in two different glycolysis related gene sets. We validated the expression of genes using qRT-PCR in U87MG cells as well as other GBM cell lines. Our results suggest novel insights on hallmark metabolic reprogramming associated with the PI3K-mTOR inhibition and provides advances in developing molecular targeted therapies.

Coral Bleaching: A Global Analysis Of Bright Spots, Shannon Elizabeth Sully

Theses and Dissertations

Thermal-stress events associated with climate change cause coral bleaching and mortality that threatens coral reefs globally. Yet coral bleaching and coral cover patterns vary spatially and temporally, and few studies have identified bright spots where corals have the potential to survive through climate change. This study synthesizes over 10,000 field observations globally of coral bleaching and coral cover from 1997to 2017 and uses a suite of environmental and temperature metrics to analyze coral bleaching and coral cover patterns. The objectives of this dissertation are to(1) identify the environmental variables that constitute bright spots for coral reefs, and (2) identify where …

Role Of Herbivore Associated Elicitors In Plant Defense Signaling, Akanksha Gandhi

Theses and Dissertations

Chapter 2: In this chapter, I have provided an update on recent developments and advances on early signaling events in plant-herbivore interactions, with a particular emphasis on the membrane potential changes (Vm), calcium (Ca2+), reactive oxygen species (ROS) and plant ion channels involvement in early signaling events initiation and propagation of defense signaling cascade.

Chapter 3: In this chapter, we show that tobacco hornworm (Manduca sexta) caterpillar oral secretion (OS) induces ROS in tomato (Solanum lycopersicum) protoplasts. By using a dye-based ROS imaging approach, our study showed that the application of Plant-Fed (PF) M. sexta OS …

Bioinformatic Analysis Of Venom Proteins From Dasymutilla Occidentalis, Eva Gunawan

Theses and Dissertations

Venom proteins have been found in a wide range of species in the animal kingdom. These venoms serve various functions such as defense against predators, hunting for food, and parasitism for reproduction. Because of their diverse functions, venom proteins are utilized in agrochemical treatments for protection from pests as well as treatments to control human diseases. Venoms, including those coming from a range of insect species, have been manipulated for these purposes, but many remain uncharacterized. Currently, one of the orders that venom-based research is focusing on are parasitoids from the order Hymenoptera. The purpose of some venom proteins in …

Enhancement Of Abiotic Stress Tolerance In Rice And Soybean By Biotechnological And Nanotechnological Approaches, Sudha Shanmugam

Theses and Dissertations

Abiotic stress is one of the major factors which affects plant productivity. The generation of stress-tolerant crops is a pressing need and a major challenge in the field of plant biology. Rice and soybean are the major crops in Arkansas that significantly contribute to state’s economy. Arkansas is one of the hardest-hit states during the drought season. Several approaches have been used for the regulation of abiotic stress tolerance in crops. Here, we have used two different approaches: the classical genetic engineering approach and the nanotechnological approach for improving plant growth as well as enhancing abiotic stress tolerance in the …

A Histopathological Review Of Immune Response In Largemouth Bass To Parasitic Infections Of Soft Tissues, James D. Stephenson

Theses and Dissertations

The immune response can serve as a key indicator of a fish’s overall health and the effect stressors have on the health of the fish. Anthropogenic factors can stress a fish’s immune system and inhibit immune responses. This study investigated the response of eosinophilic cells and macrophage aggregates to parasites in the livers, spleens, and gonads of Largemouth Bass, Micropterus salmoides. Largemouth Bass were sampled from three bodies of water in the Chattahoochee Valley of varying levels of urbanization. Histopathology of the aforementioned organs was conducted to observe both the parasite density and immune response. Eosinophilic cells were shown …

Examining The Efficacy Of Cover Crops As An Integrated Pest Management Tool In Organic Farms In The Lower Rio Grande Valley, Lili M. Martinez

Theses and Dissertations

The Lower Rio Grande Valley (LRGV) consists of a mix in subtropical and costal habitats, a combination that provides a favorable environment for the animals and plants that inhabit it. This is a problem for organic farmers as they refrain from using synthetic chemicals and therefore led them to seek other methods of dealing with insect herbivory. Of the many alternative methods available, we looked specifically at integrated pest management methods (IPM) to determine their efficacy in reducing insect herbivory among cash crops. Chapter II discusses an experiment performed in an organic farm in Edinburg, Texas consisting of a two-year …

Identifying Positive Selection In Multiple Subspecies Of Xylella Fastidiosa, Daniel Doroteo Flores

Theses and Dissertations

For this study, we will be looking to identify positive selection in eight genomes of the bacterial plant pathogen Xylella fastidiosa. A previous study used a branching method that identified 2 genes with positive selection along with a site-specific method identifying 34 genes showing positive selection. This current study focused specifically on the site-specific method, resulting in 28 genes (of 1,039 tested) showing positive selection. Of the 28 genes showing positive selection, 12 of them come from the pathogenicity, virulence and cellular structural categories. The remaining genes are found in the biosynthesis, metabolism, macro metabolism, and cellular process categories. …

Genetic Analysis Of Pi3k And Mtor Inhibition In U87mg Glioblastoma Cell Line, Carl G. Litif

Theses and Dissertations

NVP-BEZ235 is a Glioblastoma Multiform chemotherapeutic dual PI3K/mTOR pathway inhibitor created in 2008 and has since been proven experimentally to induce pluripotentcy in oncological cell populations. The inhibition of PI3K and mTOR has shown to coerce phenotypes associated with stem cell markers, most notably OCT4. It is necessary to understand the genetic composure of how PI3K/mTOR inhibited tumor cells are bypassing the canonical pathway for proliferation and growth and utilizing other parallel sources for tumor invasion into other neural regions. Taking a genetic approach with RNA-sequencing allowed us to gain insight into how glioblastoma interact with cytoskeleton factors MAPK4 and …

Optimizing Species Selection For Forest Restoration In The Lower Rio Grande Valley, Faeqa Mohsin

Theses and Dissertations

Over the past four decades, the Lower Rio Grande Valley has been reforested with over 3.3 million native thornscrub plants in old agricultural land through transplanting native species. However, assessments of LRGV forest restoration efforts are scarce, and to address the knowledge gap, this study examined species-specific responses to restoration interventions (RIs) aimed at minimizing seedling mortality for optimizing species selection. A critical period for forest restoration in old croplands is the seedling stage, where high mortality occurs due to the interactive effects of abiotic stress, compromised soil nutrient status from intensive agriculture, and mammalian herbivory. So, we evaluated seedling …

The Long-Term Persistence And Tissue Tropism Of Brazilian Zika Virus In Monodelphis Domestica, Marisol Morales

Theses and Dissertations

Zika virus (ZIKV) rose as a major public health concern due to the congenital abnormalities of infants born to infected mothers during the 2015 Latin American outbreak. While animal models such as transgenic mice and nonhuman primates are used to study ZIKV pathogenesis, they display various limitations. Additionally, the persistence and tissue distribution of long-term ZIKV infection remains unknown. We describe the laboratory opossum, Monodelphis domestica, as a potential new model for ZIKV pathogenesis research to address these issues. We utilized immunohistochemistry, RT-PCR, and ELISA to show that: infant animals inoculated intracerebrally were susceptible to infection, ZIKV infection persisted …

Embryonic Exposure To The Synthetic-Progesterone Levonorgestrel (Lng) Results In Hyperactive Behavior In Zebrafish (Danio Rerio), Austin D. Fuentes

Theses and Dissertations

Exposure to endocrine-disrupting chemicals has been associated with an increased risk of anxiety-like behavior at various life stages. Levonorgestrel (LNG), a synthetic contraceptive, could potentially alter steroidal regulated brain development based on the findings of this thesis. In-silico measurements were used for comparing LNG, which had been found in surface water, to chemical databases to predict the bioavailability, half-life, and estrogen binding potential. Zebrafish (Danio rerio) for illuminating the effects of LNG exposure during early zebrafish embryonic development, similar to fetal development, on behavior was investigated. Our data suggests exposure in a dose-dependent manner of LNG can potentially …

Analysis Of The Role Of Dnaa Recognition Site Position In Directing Assembly Of The Pre-Replicative Complex In Escherichia Coli, Christopher Aaron Czerwonka

Theses and Dissertations

Prior to initiating new rounds of DNA replication, all cells assemble pre-replicative complexes (pre-RC) consisting of initiator proteins and regions of DNA termed origins of replication. In the bacterial model system, E. coli, multiple copies of the initiator protein, DnaA,assemble into a complex with the unique chromosomal replication origin, oriC, to produce a pre-RC that unwinds the DNA helix, preparing the origin for the new replication forks. Nine base pair (bp) low affinity DnaA recognition sites are distinctly arrayed in each half of oriC and both arrays are bounded by high affinity recognition sites. Although it is known that DnaA …

Determination Of The Summer Origins Of American Kestrels ( Falco Sparverius ) Wintering In Northern And Central Illinois, Taylor P. Joray

Theses and Dissertations

The seasonal and interannual movements of the American Kestrel (Falco sparverius) are not fully understood. Although one of the most widespread and abundant raptors found in North America, information on where many populations summer and overwinter is lacking. We used stable hydrogen isotope values obtained from feathers (δ2Hf) of known origin to create age-specific calibration functions for juvenile and adult American Kestrels. We then used these calibration functions to determine the most likely summer origins of the American Kestrels that wintered in northern and central Illinois during 2015-16, classified these individuals as year-round residents or wintering migrants, and validated these …

Dissecting Dystrophin's Roles, Subcellular Organization, And Functional Network In Drosophila Oogenesis, Mina Amini Moghaddam

Theses and Dissertations

Mutations in the giant actin-membrane linker protein Dystrophin (Dys) are the cause of Duchenne Muscular Dystrophy (DMD). In the Drosophila model system, the highly conserved Dys protein is not required for viability but is required for proper wing and ovarian development. Dys mutations produce two visible phenotypes: posterior crossveins are detached from the longitudinal veins, and in oogenesis the developing eggs fail to elongate properly. This provides an opportunity to explore the less-understood cellular and developmental roles of Dys and gain a new insight into how tissues adopt their correct shapes.

Animals from worms to flies to humans express multiple …

Investigating The Regulation And Role Of P38 Mapk In Collagen-Related Limb Girdle Muscular Dystrophy, Briseida Oceguera-Perez

Theses and Dissertations

Aging is an expected and normal process across living organisms. It is characterized as a loss of stress resistance, degeneration of tissues, and decline in motor function that happen gradually across lifespan. Susceptibility to neurodegenerative and dystrophic conditions also increase, and unlike aging, are not a normal aspect of lifespan. Discerning the difference between normal and aberrant aging states will give insight into the mechanisms behind the progressive dysfunction shared among organisms. Previous work in our lab has shown that the aging gene p38 MAPK in Drosophila melanogaster plays a significant role in the aging process through its downstream effects …

Vertical Transmission And Venereal Transmission Of Zika Virus In A Population Of South Texas Aedes Aegypti, Jeremy Marshall

Theses and Dissertations

Zika virus has become a greater global public health concern from the occurrence of outbreaks in 2007 and its expansion to the Americas in 2015. The presence of Aedes aegypti in the Lower Rio Grande Valley and evidence of local transmission of Zika in Brownsville, Texas provides a need to research transmission dynamics of local populations. In these experiments, a locally acquired, laboratory colony of Aedes aegypti mosquitoes were infected with a blood meal featuring a Mexican isolate of Zika virus to display vector competency, vertical transmission, venereal transmission. Here, we infected 39 females, with 34 of them displaying evidence …

Insect Mediated Species Interactions: Examining Methods To Improve Artificial Buzz Pollination And Testing The Effects Of Plant Based Bioactive Compounds On Herbivore Life-History Traits, Mandeep Tayal

Theses and Dissertations

Pollination and herbivory are two major interactions in insect-plant ecology. Specialized pollination systems such as buzz pollination where pollen grains have to be extracted by bees with special thoracic vibrations and indirect flight muscles, is observed in ~6% of all flowering plants. Breeding and research programs in these species demand artificial pollination, but natural buzz pollinators are unreliable for this purpose. To find an alternative, we tested the pollen extraction efficiency of using inexpensive electric toothbrush over tuning fork (another commonly used device) in two buzz-pollinated species (Tomato and Silverleaf nightshade) at different buzzing frequencies and multiple buzzing time intervals. …

The Role Of Chromatin Remodeling Protein And Transcriptional Repressor, Ing4, In Hematopoiesis Regulation, Melanie Rodriguez

Theses and Dissertations

The hematopoietic compartment is tasked with the establishment and maintenance of the entire blood program. Key to this process are hematopoietic stem cells (HSCs), which possess the unique ability to self-renew and differentiate to replenish blood cells throughout an organism’s lifetime. In a screen for epigenetic regulators of hematopoiesis in zebrafish, we identified chromatin remodeling protein and transcription repressor, Ing4, as a requirement for hematopoietic stem and progenitor cell (HSPC) specification. Ing4, a member of the inhibitor of growth (ING) family, is a subunit of the HB01-JADE-hEAF6 histone acetyltransferase complex responsible for most nucleosomal histone H4 acetylation in eukaryotes. Ing4 …