Digital Commons Network^™

Wildlife Road Mortality Patterns In South Texas And Survey Methodology Improvement, Bradley E. Beer

Theses and Dissertations

Mortalities of wildlife caused by collisions with vehicles along roads are increasing in prevalence, threatening the existence of various species and populations. A better understanding of how mortalities change in response to natural and anthropogenic variables and efficient methods of obtaining mortality data are essential to mitigating such mortalities. This thesis investigates several key elements to improving road mortality surveys in south Texas. First, it was found that road mortality survey counts did not change under a pandemic-related lockdown and that 2 mortality survey observers detect more mortalities than 1. Analysis of brown pelican groundings on Texas State Highway 48 …

The Molecular Evolution Of Insect Opsin Genes, Maria Jose Cardenas Muedano

Theses and Dissertations

Opsins are part of the superfamily of G-coupled receptor proteins and together with chromophores, are responsible for initiating the signal transduction cascade responsible for animal vision. Since opsins have a critical role on visual perception these genes are crucial for a myriad of adaptive traits and behaviors and should show diverse signs of natural selection at the molecular level. Understanding the evolution of opsins across the wide diversity of insect groups will allow us to better understand the evolutionary pressure on insect opsins and serve as a model for both other gene systems and other taxonomic groups of animals that …

Effects Of Roundup Exposure On Redox Status, Cellular Apoptosis, And Antioxidant And Osmoregulatory Enzyme Expressions In Goldfish (Carassius Auratus), Md Imran Noor

Theses and Dissertations

Intense anthropogenic activities of industrialized nations dramatically increase environmental pollution. This study focused on the effects of Roundup, a glyphosate-based herbicide, exposure (low- and high-dose: 0.5 and 5 mg/L for 2 weeks) on dinitrophenyl protein (DNP), nitrotyrosine protein (NTP), superoxidase dismutase (SOD), catalase (CAT), Na+ /K+ - ATPase (NKA), and renin expressions, and cellular apoptosis in the gills and kidneys of goldfish. Histopathological analysis showed widespread tissue damage in both gills and kidneys. Immunohistochemical analysis provided insights into the expression of molecular biomarkers in tissues. Fish exposed to Roundup exhibited a significant (P<0.05) upregulation in DNP, NTP, SOD, and CAT expressions, and apoptotic nuclei in both tissues. Additionally, exposure to Roundup significantly increased renin expression in kidneys and decreased NKA expression in gills. Overall, our results suggest that exposure to Roundup induces oxidative/nitrative stress and cellular apoptosis and alters osmoregulatory and antioxidant systems which may lead to impaired physiological functions in goldfish.

Influence Of Glucose And Lactic Acid On Macrophage Transition In Pancreatic Tumors, Anyssa A. Rodriguez

Theses and Dissertations

Pancreatic cancer is the seventh leading cause of cancer-related mortality worldwide. According to the American Cancer Society, it is the eleventh most common cancer diagnosed in both men and women in the United States. Pancreatic ductal adenocarcinoma (PDAC) comprises 90% of all pancreatic malignancies and is associated with poor clinical outcome because of late diagnosis and resistance to therapy. In addition, studies show that the tumor microenvironment has become an emerging interest in cancer research due to its complex components and unique characteristics that aid in cancer initiation, maintenance, and progression. Accumulating evidence signifies that tumor associated macrophages (TAMs) play …

Grapefruit Peel Biochar Applications For Immobilizing Copper And Lead In Soil, Michael Alfredo Navarro

Theses and Dissertations

This study investigated the efficacy of grapefruit peel (GP) derived biochar materials (two pyrolysis temperatures 450°C and 800°C) as a potential adsorbent to immobilize heavy metal (copper and lead) in a local sandy loam clay soil. A batch adsorption test with heavy metal concentrations at 50 mg L-1, and 100 mg L-1 revealed that soil itself had the highest immobilization percentage compared to the GP biochars. A soil column experiment was conducted to determine how much the GP biochar samples and the tested soil will exhibit adsorptive characteristics for heavy metals when 50 ml of 50 mg L-1 copper or …

Weather Parameters Influencing The Incidence Of Citrus Canker Caused By Aw Strain In The Rio Grande Valley, Amit Sharma

Theses and Dissertations

Citrus canker caused by bacterium Xanthomonas citri subsp. citri (Xcc) seriously affects the citrus industry by making the fruit unmarketable due to unsightly lesions on the fruit. Canker caused by Aw strain of Xcc was reported in the citrus trees located in the residential areas of the Rio Grande Valley (RGV). Canker severity differs amongst cultivars/varieties, and it is influenced by prevailing environmental conditions. Multiple regression modeling of the disease incidence with the environmental variables such as temperature, humidity, windspeed, wind gust, and rainfall was performed to understand the environmental conditions that are favorable for spread of citrus …

South Texas Wildlife Activity Across A Fragmented Landscape And Road Mitigation Corridor, Caitlin K. Brett

Theses and Dissertations

Wildlife crossing structures (WCS) and roadside fencing are commonly installed to mitigate habitat fragmentation, wildlife road mortalities, and other negative effects that roads can have on the surrounding landscape. Eight such WCS were constructed below Farm-to-Market (FM)106 in Cameron County, Texas, across a 16 km corridor transecting the Laguna Atascosa National Wildlife Refuge. These WCS, paired with adjacent roadside fencing, were intended to prevent road mortalities of the endangered ocelot (Leopardus pardalis) and to mitigate the barrier effect of FM106 on this and other meso-mammal species. This study will analyze camera trap data from roadside and habitat reference …

Dynamic Soil Properties In The Lower Rio Grande Valley: Understanding Responses Of Infiltration Rate, Bulk Density, Aggregate Stability To Different Tillage Practices, Temiloluwa Faith Awotoye

Theses and Dissertations

Dynamic Soil Properties (DSPs) are soil properties that change in response to both natural and human-caused interruptions and pressures such as agro-based and wildland management. These soil properties can transform for months or even years in response to the farm use and management procedures. This research project investigates the relationship between different dynamic soil physical properties and tillage practices in the Texas Hidalgo sandy clay loam benchmark soil series. Data analyses was done to compare the effect of tillage to these soil physical properties and build a discussion about relationships between on-farm practices to other aspects of farm viability. We …

Bobcat Identification, Abundance, And Behavior At Road Mitigation Structures In South Texas, Victoria Hanley

Theses and Dissertations

Highways in South Texas fragment the landscape and result in high road mortality rates for the endangered US ocelot (Leopardus pardalis). In response, the Texas Department of Transportation constructed nine wildlife crossing structures (WCS) on Farm-to-Market (FM) 106 which adjoins Laguna Atascosa National Wildlife Refuge in Cameron County, Texas. With ocelots being rare and elusive, bobcats (Lynx rufus) are often used as a surrogate species to study felid behavior at road mitigation structures in South Texas. Bobcats have unique markings which allow them to be individually identified. Three methods of individual identification of bobcats using camera …

An Assessment Of Physical And Microbial Dynamic Properties Sensitive To Tillage Practices In Hidalgo Sandy Clay Loam Soils, Rocio N. Hernandez

Theses and Dissertations

Mechanized tillage is known to impact the dynamic physical, biological and chemical properties of a given soil, and as a result, can cause systematic harm to the soil’s function (Alam et al., 2014). The aim of this study is to assess how a series of land management tillage practices will impact dynamic physical and biological soil health parameters such as aggregation, carbon, respiration, and enzymatic activity (β-glucosidase). According to Acir et al (2020), the aforementioned soil parameters are both co-influenced and dependent, indicating a response to tillage is likely. A total of 198 samples of Hidalgo series soils were collected …

'Good Food’ And Food Sovereignty In The South Texas Borderlands: A Qualitative Investigation Of Alternative Retail Food Outlet Managers And Owners, Kanyanat Lertkhonsan

Theses and Dissertations

This case study describes how Alternative Retail Food Outlets (ARFOs) managers and owners in a county in South Texas near the U.S. – Mexico border I am calling Esperanza County, decide what food to eat and to sell. Data from qualitative interviews reveals that the South Texas socioeconomic – cultural context and informants’ economic constraints shaped two different conceptions of good food. At the same time, informants’ socioeconomic backgrounds and sources of good food reveals that the power to define good food – as organic, local, and seasonal – and those that can access it tend to be the educated …

Influence Of Pretreatments On Physiological Status And Post-Planting Survival Of Thornforest Seedlings In A Restoration Context, Douglas E. Mainhart

Theses and Dissertations

Semi-arid ecosystems across the globe have faced land conversion posing a threat to the important ecosystem services they provide. Revegetation-centered restoration efforts in arid regions have low success due to limited water availability and higher temperatures. Typically, practitioners utilize methods that modify field conditions around seedlings to mitigate these stressors. I evaluated the efficacy of in-nursery treatments to improve plant water status. Three pretreatments were applied: elevated CO2, drought hardening, and an antitranspirant foliar spray. My goal was to understand how these pretreatments would impact survival and growth in the field and what physiological traits they altered. Elevated CO2 and …

Effects Of Disturbance (Mowing) On Florivory And Floral Defenses In Solanum Elaeagnifolium, A Noxious And Worldwide Invasive Weed, Alejandro Rafael Vasquez Marcano

Theses and Dissertations

Chapter 1: Literature Review- In this literature review we have examined weed management as it concerns urban and agricultural ecosystems, as well as the need for mowing assessments as it relates to floral traits and defense against herbivory.

Chapter 2: Experiments- In the experiments we examined the role of mowing on floral growth traits, floral defense traits, and their effect on Manduca sexta specialist herbivores.

Chapter 3: Results- In the results we found SLN flowers to have larger diameters than unmowed flowers; however, flower mass was in line with our predictions as unmowed flowers were heavier in high mowing frequency …

Incorporating Native Plants In Insectary Strips To Promote Insect Diversity And Below-Ground Beneficial Microbes In South Texas, Lindsey N. Richards

Theses and Dissertations

Farm edges are generally the most undisturbed areas in a farm with diverse vegetation and can enhance agrobiodiversity and provide crucial food and shelter for wildlife, insects, and soil biota. Planting native wildflowers with the ability to reseed and withstand local climatic conditions for semi-permanent vegetation around farm edges or in between crops has potential to biologically control pests. To test this, we ran a two-year study and installed three different flowering insectary strips on a certified organic vegetable farm in South Texas during the winter season. The treatments were: 1) a commercially sourced 17-species native wildflower seed mix; 2) …

Quantifying And Predicting Drought Performance In Woody Semi-Arid Seedlings In South Texas: Implications For Enhancing Drought Resilience In Restoration, Zarek Contreras

Theses and Dissertations

Increasingly frequent and severe droughts in the Lower Rio Grande Valley National Wildlife Refuge have been observed to cause large variation in species-specific mortality patterns in young seedlings, spanning 6 – 43 % mortality within the first year. To understand the underlying mechanisms behind this, we subjected seedlings of five woody semi-arid species (Celtis pallida, Forestiera angustifolia, Sideroxylon celastrinum, Phaulothalmnus spinescens, and Zanthoxylum fagara) to a point-of-no-return drought experiment in order to (1) identify potential metrics capable of predicting species wilting and mortality responses, and (2) to understand the underlying mechanisms that correspond to species drought performance …

Examination Of Amphibian Community And Environmental Relationships In South Texas Using Environmental Dna (Edna), Sean Michael Collins

Theses and Dissertations

Developing more efficient tools to assess amphibian biodiversity and understanding what environmental variables drive amphibian biodiversity are top priorities, as amphibians are facing extinction events across the globe. Environmental DNA (eDNA) surveys are a promising new tool to asses amphibian biodiversity. Throughout the study eDNA metabarcoding along with a targeted eDNA assay and traditional survey methods were used to provide foundational information on amphibian community assemblages throughout South Texas. Water quality, habitat characteristics and soil composition data were collected and used to examine environmental relationships. eDNA metabarcoding detected significantly more amphibian taxonomic units compared to traditional survey …

Body Composition, Muscular Strength, Arterial Stiffness, And Hemodynamics Responses To Various Training Protocols In Young Males, Jorge Bejar

Theses and Dissertations

PURPOSE: The purpose of this study was to compare the effects of 8 weeks performing various resistance training protocols with and without blood flow restriction (BFR) on muscular strength, body composition, arterial elasticity, and hemodynamics responses in young males.

RESULTS: Significant time*condition interactions occurred in HR period (p <0.05), HDI SBP (p <0.05), HDI MAP (p <0.05), and SV (p <0.05). Trends for time*condition interactions were found in HDI DBP (p=0.054), HDI HR (p=0.051), and HDI SVR (p=0.085). Significant time main effects occurred in all strength measures (p <0.05). Significant condition main effects occurred in Aortic DBP (p <0.05), Brachial DBP (p <0.05), and LAE (p <0.05). Total lean mass significantly increased from baseline the HI condition only (p<0.05).

CONCLUSION: Significant improvements in lean mass were seen following the HI and BFR protocols. However, decreases in LAE were found following the HI protocol only. It appears that performing aerobic exercise after resistance training can negatively affect muscle growth. However, only 15 min of moderate-intensity aerobic training can improve hemodynamics in young, …

Assessment Of Nitrogen-Based Fertilizer Transport And Microbial Activities In Sandy Soil Profiles In South Texas, Gladys De La Rosa

Theses and Dissertations

Conventional farming is a common practice in Lower Rio Grande Valley (LRGV) and the application of nitrogen fertilizer is essential for plant growth and support. However, managing the rate of nitrogen that is applied can benefit farmers financially and reduce nitrate leaching that can have an adverse effect on the local environment and aquatic systems, e.g., rivers and estuaries. Sandy soils are more vulnerable to water infiltration due to the large proportion of macropores. This study aims to (i) assess how nitrate from a variety of fertilizers (i.e., synthetic and organic) distributes on the top 60 cm layer of a …

Revealing The Effects Of Climate Change And Fungicides On Soil Microbial Communities In The Lower Rio Grande Valley, Texas, Armida Rivera

Theses and Dissertations

Fungicide applications are effective to prevent fungal pathogens that are known to cause crop damage and decrease yields. However, these pesticides can exert toxic or inhibitory effects on non-targeted organisms such as soil microbial communities. In addition, it is unknown to what extent shifts in temperature and soil moisture resulting from global climate change, alter the activities of non-targeted soil organisms. The aim of this study was to evaluate soil biological parameters such as soil respiration and enzyme activities involved in the cycling of carbon, nitrogen, and phosphorous (Beta-glucosidase, Fluorescein Diacetate (FDA) Hydrolysis, urease, alkaline phosphatase, acid phosphatase, and N-acetyl-Beta-glucosaminidase) …

Tree Ring Reconstructions Of Streamflow For The Lower Rio Grande Valley Of Texas, Adedolapo Mutiyat Adeyanju

Theses and Dissertations

The Rio Grande River is a major water source for people living within the USA-Mexico border. The Rio Grande River has its headwaters in the San Juan Mountains in Colorado and the Sierra Madre Occidental in Mexico before flowing into Texas through El-Paso. The water supply issues facing the Lower Rio Grande Basin (LRGB) are extremely complex from international restrictions to severe climate change. The river shares its flow between the U.S.A and Mexico based on the provisions of the 1944 treaty between the U.S.A and Mexico. The LRGB flow is regulated by releases from Falcon and Amistad Reservoirs managed …

De Novo Transcriptome Analysis Of Orange Jasmine (Murraya Paniculata) Infected With Citrus Greening Disease, Jeffrey Aquino Gomez

Theses and Dissertations

Citrus greening disease, also known as Huanglongbing, is one of the most devastating citrus diseases in the world. Candidatus Liberibacter asiaticus (CLas) is a non-culturable, phloem-limited bacterium that serves as one of two vectors for the transmission of any of the three kinds of greening disease. In cooler climates, the African variant transmitted by the African citrus psyllid (Trioza erytreae) is more prevalent. The Asian form transmitted by the Asian citrus psyllid (Diaphorina citri) where is predominant in warmer conditions and recently discover the American form who is also transmit by Diaphorina citri, was discover in Brazil but has also …

Cytochrome C: A Potential Early Biomarker Of Diabetic Retinopathy, Ileana G. Villarreal

Biology Dissertations and Theses

Diabetic retinopathy is an ocular disease which appears in patients who experience progression of diabetes mellitus over a continuous period of time. Oftentimes, patients remain undiagnosed through the first stages of diabetic retinopathy due to the fact that there is not a specific way to determine when a patient develops the disease. Ophthalmologists and other eye specialists diagnose a patient with diabetic retinopathy once the patient begins to show progressed symptoms of the disease. Previous experiments have been performed to increase our knowledge of diabetic retinopathy and early biomarkers of the disease. Several studies have determined the effects of diabetic …

Examination Of The Realized Host Range Of North American Lacebug (Gargaphia Arizonica Drake & Carvalho) And Texas False Potato Beetle (Leptinotarsa Texana Schaeffer) As A Potential Biocontrol Agents For Silverleaf Nightshade (Solanum Elaeagnifoli Cav.), Samikshya Subedi

Theses and Dissertations

Silverleaf nightshade (Solanum elaeagnifolium Cav.) is a perennial forb native to South Texas and Central and South America, but it has become a serious agricultural weed across the world. Because silverleaf nightshade (SLN) is difficult and expensive to manage using chemical and mechanical controls, there is growing attention and research focused on biological control options. In this project, we used both field and laboratory studies to examine the suitability of two North American insects, namely North American lacebug (Gargaphia arizonica Drake & Carvalho) and Texas false potato beetle (Leptinotarsa texana Schaeffer) as prospective biological control agents for …

Targeting Ribosome Biogenesis For Pancreatic Cancer Treatment, Carlos Perez Iii

Theses and Dissertations

Pancreatic cancer (PanCa) is one of the leading causes of cancer-related death in the United States. Currently, PanCa is one of the recalcitrant cancers that has very limited therapeutic options available for its treatment. The current standard care of PanCa is gemcitabine (GEM) alone or in combination with FOLFIRINOX, nab-paclitaxel, erlotinib, or 5-FU PanCa, which often show poor response. Therefore, new treatment strategies are required for the prevention and treatment of cancer. Ribosome biogenesis process is dysregulated in most of the cancer types of results in production of more ribosomes and synthesis of oncoproteins which lead to the induction, progression, …

Targeting Mutated Kras And Galectin-1 In Pancreatic Cancer, Ana Izavelle Martinez Bulnes

Theses and Dissertations

The poor patient survival rate in pancreatic ductal adenocarcinoma (PDAC) remains a challenge. KRAS activating point mutation on codon-12 is found in 70–95 percent of PDAC patients, and no progress in inhibiting KRAS has been obtained thus far. KRASG12D is a transcription factor that controls cell proliferation, differentiation, and apoptosis. Recent preliminary and published research indicates that Galectin-1 (Gal-1) levels are high in both PDAC and stromal cells, which modulates tumor microenvironment and metastasis. As a result, we created a new combination treatment for PDAC that targets both proliferation and metastasis in PDAC by targeting mutant KRASG12D and Gal-1. This …

Screening For Potential Therapeutic Targets Of Yb-1 Protein Using A Bioinformatics Approach, Omar Muneer Karkoutly

Theses and Dissertations

Treatment options for cancer are becoming much more limited due to the robust characteristics of cancer that allows them to rapidly develop drug resistance. This may be a result of cancer cells’ ability to switch between differentiated and undifferentiated states (plasticity). Diagnostic measurement and detection of cancer and its progression is essential for developing successful treatments. Specific cancer targets whose expressions are highly associated with increased incidence, risk, and spread of cancer therefore become perfect targets for therapeutic intervention. One such novel target that is still being studied is the Y-box binding protein 1 (YB-1), which …

Influence Of Paclitaxel Nanomedicine On The Pancreatic Tumor Immune Components, Godwin Peasah-Darkwah

Theses and Dissertations

Pancreatic cancer (PanCa) is one of the leading causes of cancer-related mortalities in the U.S due to ineffective therapeutic options. Pancreatic tumors are highly desmoplastic and inhibit efficient uptake of therapeutic payloads. Paclitaxel (PTX) has been tested in PanCa therapy with marginally better clinical outcomes, but remain limited by its poor hemocompatibility, biodistribution and intracellular accumulation in tumor cells. Thus, we synthesized a next generation nanoparticle system for PTX to improve its pharmacokinetics and pharmacodynamics (PKPD) in treating PanCa. We also examined ability of the nano formulation to potentiate gemcitabine (GEM) activity in combating chemoresistance in the pancreatic tumor microenvironment …

Cucurbitacin B: A Potential Natural Agent For Targeting Tumor Immune Cell Population, Emmanuel Anning

Theses and Dissertations

Immune checkpoint blockade (PD1, PDL-1 and CTLA-4) immunotherapies have emerged as the breakthrough in cancer treatment. However, some malignancies show marginal response. One factor that influences the efficacy of immunotherapy is the development of immunosuppressive tumor microenvironment (TME), caused by infiltration of myeloid derived suppressor cells (MDSCs) and tumor associated macrophages (TAM) into the tumor, facilitating metastatic tumor growth and immunotherapy resistance. We have identified Cucurbitacin B (Cuc. B), a potent small molecule that targets TAM and MDSCs and inhibits Stat3, CSF-1R, and PI3Kγ signaling axis at lower doses compared to the pharmacological inhibitor of PI3Kγ (IPI-549). IL-4 polarization of …

The Apoe Ε4 Allele Association With Cholesterol Related Phenotypes In The Mexican American Population, Stephanie Lozano

Theses and Dissertations

Diseases linked to high cholesterol have been well studied and several diseases-associated candidate genes have been suggested. Among these, the apolipoprotein E gene (APOE) gene associated with lipid metabolism and lipid-related traits was reported in the non-Hispanic population. There are three types of alleles APOE ε2, ε3, and ε4. The APOE ε4 allele has been identified as a biomarker for Alzheimer’s disease (AD) and cardiovascular disease (CVD). In recent years, there have been limited studies regarding the association between the APOE gene and hypercholesterolemia in the Mexican American population. Therefore, the aim of this study is to investigate …

Zinc-Mediated Regulatory Function Of Psd-95 On Nmdar At Post-Synapses, Luis F. Acosta

Theses and Dissertations

Postsynaptic density-95 (PSD-95) is a membrane-associated guanylate kinase that mediates localization of receptors in the excitatory postsynaptic density. It has been reported that PSD-95 mediates postsynaptic localization of NMDA receptors and anchors postsynaptic AMPAR receptors mainly through its postsynaptic membrane targeting by its N-terminal palmitoylation. Recent studies have shown that Ca2+/calmodulin blocks palmitoylation of PSD-95 by binding at the N-terminus of PSD-95, which promotes dissociation of PSD-95 from the postsynaptic membrane and causes loss of surface AMPARs in cultured neurons. Another metal ion zinc is found in various areas of the brain. As an endogenous neuromodulator, zinc plays a role …