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Duet Phonology And Syntax Of The Red-Crowned Parrots In South Texas, Abigail Pozulp

Theses and Dissertations

Bird behavioral interaction systems show a preference for temporal precision. This preference is exemplified in the way many species avoid masking of vocal signals. Antiphonal duetting in songbirds suggest that overlapping notes are a sign of poor temporal coordination which can signify a weak pairbond, a possible cue for conspecifics seeking to usurp territories or mates. However, parrots (Psittacidae) are accomplished yet understudied duetters in nature. I recorded antiphonal duets produced by a wild population of red-crowned parrots (Amazona viridigenalis) in Brownsville, Texas. Temporal and acoustic variation of signals was assessed within and across a sample of mated …

Home Range Dynamics And Juvenile Dispersal Of Gray Hawks In The Lower Rio Grande Valley, Michael Stewart

Theses and Dissertations

Using GPS-GSM transmitters I determined when 14 juvenile Gray Hawks (Buteo plagiatus) in the Lower Rio Grande Valley of Texas fledged from their natal areas and how far they traveled once they dispersed. These transmitters also allowed me to calculate home range sizes for 22 adults. Additionally, with the GPS-GSM transmitters and 15 VHF transmitters, I discovered that adult Gray Hawks in the study area remained in their territories year-round. Home range sizes were calculated using the minimum convex polygon estimator, the estimation of kernel home-range, and the estimation of kernel Brownian bridge home-range. The same three methods allowed me …

Morphological Characterization And Functional Assessment Of Trichomes In Solanaceae, Sakshi Watts

Theses and Dissertations

Chapter 1: This chapter provides an overview of various trichome types in plants, and also empirically examines their variation on abaxial and adaxial leaf surface of 14 Solanum species. Detailed nomenclature, density, and dimension measurements of each trichome type has been provided using scanning electron-microscopy.

Chapter 2: Scanning electron microscopy was major component of methodology used in my thesis for scanning leaf samples to estimate trichome traits. In this chapter, a more efficient and cost-effective methodology for scanning electron microscopy has been explored.

Chapter 3: This chapter examines the relationship of trichome density and herbivore feeding behavior using abaxial and …

Exploring The Role Of Stigmatic Exudate In The Water Lily (Nymphaceae) Pollination Mechanism Using N. Ampla (Salisb. Dc.), Luis Uribe

Theses and Dissertations

Water lilies are the only known plant group that uses hyperactive nectar glands to divest pollinators of their pollen. The nectar in Nymphaea ampla is thought to contain secondary metabolites that increase pollen deposition possibly by modifying pollinator behavior. This was explored utilizing visitation and fecundity data from the field coupled with survival and behavioral experiments in the laboratory. Replacing nectar with water reduced seed set in N. ampla which was attributed to reduced visitation in water-bearing flowers and not to effects on pollinator detention time. Exposure to nectar did not reduce survivability in Apis mellifera. Pollen and nectar foragers …

Characterization Of Soil Nematode Community As Influenced By Weedy Plants And Edaphic Properties, Orlando Garcia

Theses and Dissertations

Nematodes are one of the most critical species globally as they are part of most nutrient recycling. While nematodes play a vital role in nutrient cycling, little is known about them from an ecological standpoint. The majority of current research has focused on a singular component of the community, being those of herbivore/plant-parasitic nematodes. In this study, the community shifts of the nematode trophic groups were analyzed as influenced by native and invasive grasses species in the Lower Rio Grande Valley (LRGV) with the addition of edaphic soil properties.

In our study, the results indicate changes in the composition of …

Early Embryology In Collembola With An Emphasis On Wing Development, Samantha A. Gonzalez

Theses and Dissertations

The primary objective of this study was to further the understanding of the wing origin in insects. Currently there are several theories which are popular such as the tergum theory, the pleural plate theory, and the dual theory of wing origin. Studies for these theories have been done on crustaceans, the ancestors to modern day insects. By utilizing a pre insect hexapod, it may be possible to better understand the transition to insect wings. Members of the Collembola species Hypogastrurid are one of these pre-insect hexapods which may provide a clue into origins of wing development. During this study, the …

Prospecting For And Isolation Of Microalgae In South Texas, Mauricio Alejandro Peña

Theses and Dissertations

Microalgae is a very important microorganism that can be used for beneficial purposes for humans. One way to show the importance of algae in this planet is the contribution of Oxygen it provides to the atmosphere, which many organisms rely on (Medeiros et al., 2015). Carbon footprint has been one of the greatest causes for global warming and it is due to the use of fossils to create diesel. One of the ways to avoid contamination is to replace those fuels that are used on daily basis, such as for transportation. The microalgae are able to produce lipids that can …

Soil Chemistry Modification By Guinea Grass In Semi-Arid Soils: A Litter Mediated Positive Feedback, Vanessa Elizabeth Thomas

Theses and Dissertations

Nutrients are a key component of healthy soils. Their composition plays an important role in plant growth through nutrient cycling and directly influences the functioning of plant communities in both agricultural and natural ecosystems. Shifts in macronutrients such as phosphorus and nitrogen may be initiated by invasive growth as a driver for competition with native plants. The goal of this study is to explore the plant soil feedback in an exotic invasive plant, Guinea grass (Pancium maximum), an invasive bunch grass originally from Africa, across different habitat types in the Lower Rio Grande Valley (LRGV). To determine a positive plant …

Investigation Of Techniques And Their Application For The Cryopreservation Of Algal Species, Jazmine Leija

Theses and Dissertations

An alternative source for petroleum-based crude oils are algae derived biofuels. Fossil fuels are harmful for the environment, expensive and becoming scarce. There has been an increase in research on environmentally sustainable energy, using lipids derived from microalgae, which can be converted into biofuel. The use of microalgae as a source for biofuels has a lot of benefits including decreasing greenhouse gas emissions, rapid fuel production, absorption of carbon dioxide, and production of a renewable source of energy.

Algae cryopreservation aids in the maintenance of the best algae strains selected for producing lipids for biofuels. Cryopreservation will help minimize genetic …

Effects Of Early Corticosterone Treatment On Vocal Babbling In Wild Green-Rumped Parrotlets (Forpus Passerinus), Celia Rose Mclean

Theses and Dissertations

The stress axis of the endocrine system allows for animals to respond to environmental stressors in contextually appropriate ways. Elevated levels of the stress hormone corticosterone (CORT) in male songbirds can result in compromised song learning ability. Parrots form a sister group to songbirds, but it is unknown whether CORT affects vocal development in parrots. The goal of this study was to assess the effects of CORT supplements in green-rumped parrotlets (Forpus passerinus), a free-ranging parrot species in Venezuela. Bouts of vocal babbling were extracted from nest box videos and analyzed. CORT supplementation resulted in differences in babbling …

An Assessment On Microplastic Pollution In The Resacas Of The Lower Rio Grande Valley, Texas, Wesley D. Franklin

Theses and Dissertations

Microplastic pollution is a serious issue that impacts most aquatic environments. Microplastics have the potential to cause numerous detriments to the fitness and reproductive capability of many organisms. The resacas of the Lower Rio Grande are an understudied area that could be sinks for large congregations of microplastics. We analyze microplastic pollution in two species of fish as well as the sediment and water of eleven different pools from four resaca systems. We find that microplastics are present in every pool sampled.

Altogether 218 microplastic pieces are found from the water, sediment and fish samples. We find that microplastics are …

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 …

Opa1 Modulation Of Mitochondrial Dynamics In Ac16 Cardiomyocytes, Patrick De La Torre Schutz

Theses and Dissertations

This thesis explores mitochondrial dynamics in the AC16 cardiomyocytes. Mitochondria are capable of fission and fusion, controlled by specific proteins that respond to cell stress. The transmembrane potential(∆ψm) of the mitochondria is responsible for both bioenergetic functions and regulating the activation of the OMA-1 protein, which regulates the cutting of OPA-1. OPA- 1 has two isoforms: a long (active) and short (inactive) isoforms. Our research is exploring the impact of the levels of OPA1 expression on the observed ∆ψm threshold of mitochondrial fusion. Our laboratory has demonstrated that 143B cells lose L-OPA1 isoforms at [CCCP]> 4.75 µM and …

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 …