Biology Commons^™

Understanding An Inflammatory Pathway In Diabetic Retinopathy, Reanna Raye Rodriguez

Theses and Dissertations

Diabetic Retinopathy (DR) is the leading cause of blindness in the U.S. However, not much is known of its molecular pathway and how it attributes to increases in inflammatory response in the eye. One avenue we will investigate is the transforming growth factor beta (TGFB) signaling pathway and its effect of vascular endothelial growth factor (VEGF) secretion and cell viability. VEGF is the hallmark that exacerbates DR progression in prolonged diabetes. Some major concern that have arisen are the underlying effects of oxidants and antioxidants in elevating VEGF secretion in diabetes. In attempt to learn more, we evaluated how an …

Exploration Of Antimicrobial And Cell Proliferation Properties Of Nanofibers Incorporating Nopal (O. Cochenillifera) Extract, Cristobal Rodriguez

Theses and Dissertations

This study focused on the fabrication of Forcespinning® nanofibers composed of Opuntia cochenillifera, ‘nopal’, mucilage (N) extract, chitosan (CH), and pullulan (PL) (N/CH/PL) were developed with an optimum fiber average diameter of 406±127 nm, and studied for their ability to sustain adhesion and proliferation of mouse embryonic fibroblast (NIH 3T3) cells. After a 6-day incubation period, N/CH/PL nanofibers displayed robust cell proliferation, while also exhibiting inhibitory properties through an N extract dip-coating process against gram-negative bacteria Escherichia coli in a 24 h bacterial growth study. A demonstration of integrated natural bioactive compounds with combined biodegradable polymers, provide an enhanced …

Effects Of Plant Secondary Metabolites And Host Specificity On Growth, Development, And Oviposition Of Lepidopteran Herbivores, Sukhman Singh

Theses and Dissertations

Chapter 1: This chapter provides a review of recent and critical literature on the role of polyphenols in mediating plant-insect interactions. I particularly focused on plant defense induction and mode of action of polyphenols, defense fitness trade-offs, and storage of polyphenols for future defense responses.

Chapter 2: This chapter is about the effects of polyphenol rich purple corn pericarp extract on the growth and development of generalist caterpillar i.e., fall armyworm (Spodoptera frugiperda). This study shows that purple corn pericarp extract rich in polyphenols negatively effects the growth and development of S. frugiperda.

Chapter 3: This chapter …

Assessing The Level Of Perception Of Knowledge About Ticks And Tick-Borne Diseases Among The Residents Of Several Cities In The Transboundary Region Of U.S.-Mexico, Consuelo Aguilar

Theses and Dissertations

The transboundary region of U.S.-Mexico possesses similar weather conditions and habitats favoring insects (vectors) like ticks. Several tick species found in the transboundary region of U.S.-Mexico can transmit pathogens. In the last three years, a total of 40 cases of Rickettsial infections, 28 in Tamaulipas and 12 in the Lower Rio Grande Valley, have been reported. A low level of knowledge about diseases that ticks can transmit along with a lack of appropriate protection practices can severely affect human health. Limited surveys on ticks and tick-borne disease are available. Our goal was to (1) assess the perception of knowledge of …

Winners And Losers In Reforestation Efforts In The Lower Rio Grande Valley Of Texas, And The Predictive Power Of Xylem Anatomy On Long-Term Growth And Survival, Clifton F. Albrecht

Theses and Dissertations

Reforestation has been ongoing in the Lower Rio Grande Valley annually since the 1980s, and to date over 6400 ha of land has been reforested in this area. However, there has been little subsequent study of the change and development of those forests as they mature. This thesis consists of two, interrelated, studies: (1) surveys of a five-site chronosequence of restored forests and (2) quantification of xylem anatomical traits of a subset of species present at the reforestation sites. Surveys showed a consistent reduction in species diversity and stem number density on the landscape, and identified a suite of species …

Understanding The Ecological Role, Population Dynamics, And Geographic Distribution Of Manihot Walkerae, Gisel Garza

Theses and Dissertations

Walker’s Manihot, Manihot walkerae Croizat (Euphorbiaceae), is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion. Understanding M. walkerae’s geographic distribution, populations, and species interactions can provide essential information for the development of sound conservation strategies. To this aim, I asked the following questions: 1) What is the potential geographic distribution for M. walkerae? and, will it be affected by climate change? 2) Using global and regional extinction risk assessments, what is the extinction risk category for M. walkerae after incorporating species distribution models? 3) What do natural history observations reveal about M. walkerae’s population …

Physical And Chemical Defense Mechanisms In Aloe Barbadensis Against Insect Herbivores, Zachary Johnson

Theses and Dissertations

Chapter 1: This chapter provides an overview of insect herbivore impacts on plants and plant defense mechanisms to combat them. I particularly focused on physical and chemical defenses in the broader sense.

Chapter 2: This chapter describes the experiments that showed the effects of extracts from Aloe barbadensis on the growth and development of tobacco hornworm (Manduca sexta) and fall armyworm (Spodoptera frugiperda), model herbivores used to understand herbivore growth and plant defenses. This study shows that extracts from the Aloe differentially affected the growth and development of M. sexta and S. frugiperda. This chapter …

Investigating Bmp7 Expression In Glioblastoma Multiforme, Yajaira Janett Macias

Theses and Dissertations

The PI3K/AKT/mTOR pathway regulates important cell processes such as growth, survival, motility, inflammation, proliferation, and apoptosis. In Glioblastoma multiforme (GBM) the PI3K/AKT/mTOR pathway is aberrant as it is almost always active. This results in the deregulation of downstream molecules and ultimately leads to cancer progression and maintenance in GBM tumors. In this study, we used RNA-sequencing to identify differentially expressed genes (DEGs) in U87MG GBM cells treated with NVP-BEZ235, a dual inhibitory drug targeting PI3K and mTOR. A total of 7,803 differentially expressed genes were identified via RNA-seq. GEPIA2 online tool was used to assess differential gene expression …

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 …

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 …

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.

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 …

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 …

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. …

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 …

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 …

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 …

Using Genetic Diversity To Differentiate Mosquito Populations, Rachel Christine Malampy

Theses and Dissertations

Experiment 1: Little is known about Aedes aegypti females sharing oviposition sites. We examined four different oviposition sites in McAllen, TX. A mitochondrial gene was used to analyze the variation within the oviposition site to understand how many egg-laying females are sharing oviposition sites. These results will aid in the understanding of Aedes. aegypti oviposition behavior and contribute to more effective mosquito control techniques.

Experiment 2: Mosquito flight patterns and movement from habitat to habitat can drastically influence the spread of diseases. The anthropophilic Aedes aegypti mosquito has historically been identified as having a very limited flight range. Studies also …

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. …

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 …

Investigating The Localization Of Foxo Transcription Factors In Glioblastoma, Leetoria Hinojosa

Theses and Dissertations

The Phosphatidylinositol 3 Kinase (PI3K) pathway is an essential intracellular signaling pathway that regulates cellular growth, survival, and fate. Canonically, the activation of this pathway removes forkhead box subfamily O transcription factors (FOXO -1, -3, and -4) from the nucleus. However, in cancer cells such as glioblastoma multiforme, FOXO factors are at least in part nuclear despite the activation of the PI3K pathway. Previous research indicated that FOXO3 localization was not affected when the pathway was inhibited in breast cancer cells, which challenged the conventional paradigms for FOXO factor regulation. Therefore, we were interested in investigating the nuclear localization of …

Organizational Effects Of Exogenous Corticosterone On Vocal Development In A Wild Parrot, Rory Eggleston

Theses and Dissertations

Songbirds learn songs during a plastic phase in vocal development, similar to human vocal babbling. Research has focused on male song learning, a process influenced by gonadal steroids. Like humans, parrots are very plastic vocal learners and both sexes learn vocalizations throughout life. It is unclear how the endocrine system mediates environmental information with developing phenotypes in parrots. Corticosterone (CORT) is a sex-neutral hormone that can affect cognitive development, but its role in vocal development has not been experimentally tested in wild parrots. I quantified vocal babbling from nestling Green-rumped Parrotlets (Forpus passerinus) recorded in Venezuela. Nestlings received oral CORT-oil …

Effects Of Arbuscular Mycorrhizal Fungi (Amf) On Growth And Herbivore Defenses In Sorghum Sudangrass (Sorghum X Drummondii), Jasleen Kaur

Theses and Dissertations

Chapter 2: In this chapter we have examined the role of trichomes in plant stress biology, reviewed the studies on herbivore X trichome interactions, and their role in plant defences. Ultimately, we have proposed new areas of research for future work.

Chapter 3: In this chapter, we examined whether AMF has cascading effects on insect community dynamics through attraction/repulsion of beneficial and damaging insects using Sorghum-sudangrass (Sorghum x drummondii), either inoculated with commercial AMF mix or left as control in lab and field experiments. Our results suggest positive effects of AMF on plant growth, and a lower initial incidence of …

Comparing Novel And Traditional Sampling Methodologies To Analyze The Population Status Of The Rio Grande Cooter (Pseudemys Gorzugi), Amy P. Bogolin

Theses and Dissertations

The Rio Grande Cooter, Pseudemys gorzugi, is an understudied aquatic turtle species of conservation concern in the Rio Grande, Pecos, and Devils river systems. Traditional sampling methodologies for aquatic turtle species face numerous challenges, but novel sampling methodologies, such as drone-based surveys and environmental DNA analysis, may address these issues. This study compared novel sampling methodologies to traditional sampling methodologies in mean detections and identifications of aquatic turtle species, developed and implemented an environmental DNA assay to detect P. gorzugi, and characterized P. gorzugi habitat. Following an introductory chapter, each task is addressed by chapter and formatted to …

Lipid Analysis, Fluorescence Microscopy And Flow Cytometry As Tools To Evaluate Microalgae For Potential Biofuel Production, Giovanina Aimee Hinojosa

Theses and Dissertations

Petroleum-based crude oil is nonrenewable and toxic to the environment, leading to a need for a more efficient and environmentally effective replacement. Microalgae produce lipids which can be converted to recyclable biofuels; therefore, research in lipid production by algae is becoming important for an economic and environmental sustainability. Microalgae can re-absorb atmospheric CO2 and have rapid growth, thereby lowering greenhouse gasses (GHGs) emission, renewability, and simple growth requirements.

Nannochloris sp. is a marine microalga that is amenable for lipid production because there is little research on it so this study will focus on using flow cytometry, fluorescence microscopy and other …

The Effects Of Salvia Hispanica On Biochemical Markers Related To Immune System, Hormone Regulation, And Lumbar Vertebrae In Postmenopausal Rat Model, Daisy M. Mendez

Theses and Dissertations

In women, with age and menopause there is increase in body weight and decreased immunity and bone mass. Due to severe side effects of currently available drugs for obesity and bone loss, new therapies with less side effects are sought after and alternative medications are becoming more popular. Recently, Salvia hispanica (SH), a herbal supplement is implicated in losing body weight. Currently, there is no information on how SH modulates obesity or bone health. In this study, effects of SH seed extract was investigated in a postmenopausal rat model on certain hormones, immune markers, and fourth lumbar vertebrae. The highest …