Life Sciences Commons^™

Comparison Of Soil Chemistry And Microbial Communities That Inhabit The Rhizosphere Of Native And Non-Native Grasses Of The Lower Rio Grande Valley, Jacqueline Valencia

Theses and Dissertations - UTB/UTPA

Non-native grasses can modify the soils they invade. This study investigated microbial variation among native and non-native grasses in the Lower Rio Grande Valley. We hypothesized that rhizospheres of non-native grasses would support a higher density of microorganisms; therefore microbial communities of invasive plants would exploit more carbon sources than those of native plants. A second hypothesis stated that Streptomyces bacteria from the rhizosphere of non-native grasses would be better competitors. Samples of grasses, and soil from their respective rhizospheres were obtained in Arroyo City, TX. Results indicated a higher bacterial colony density, total activity and number of substrates utilized …

Investigating Heavy Metal Accumulation And Oxidative Stress Tolerance Of Non-Accumulators And Hyperaccumulators In The Brassicaceae Plant Family, Fritzie Joy Into

Theses and Dissertations - UTB/UTPA

Physiological and enzymatic analysis indicated that the non-accumulator A. thaliana showed an oxidative stress response in all assays except for protein carbonylation. Other non-accumulator plant species showed a significant difference in oxidative stress response in the TBARS assay; however, for some assays no stress response was evident. The hyperaccumulator plant species showed no significant difference in oxidative stress as indicated by the all of the assays with the exception of T. montanum var. montanum which showed an oxidative stress response in the SOD assay. Basal catalase enzyme activity was notably higher in the hyperaccumulators T. montanum var. montanum and T. …

Dna Staged Self-Assembly At Temperature 1, Nicholas H. Guiterrez

Theses and Dissertations - UTB/UTPA

We introduce alternate temperature 1 self-assembly constructions of an n x n square by efficiently utilizing bins and stages to achieve desirable results. These bins are able to contain a variety of tiles or supertiles, which are then mixed together in a pre-determined sequence of distinct stages. The basic 2D tile assembly model at temperature 1 uses 2n-1 tile types to construct a square. The model only utilizes one bin and occurs all in one stage. We will demonstrate how the use of bins and stages will allow for the construction of these squares more efficiently.

Bronzed Cowbird (Molothrus Aeneus) Habitat Use And Differential Response To Playback Of Host Song, Mary Jennifer Gorton

Theses and Dissertations - UTB/UTPA

During the breeding seasons of 2008 - 2009, 180 fixed-radius point-count surveys and broadcasts of host song were conducted in Santa Ana (SANWR) and Laguna Atascosa (LANWR, 2009 only) National Wildlife Refuges to identify Bronzed Cowbird (Molothrus aeneus) habitat use and test the predictions of the host activity hypothesis. Surveys demonstrated that Bronzed Cowbirds were distributed across all habitat types in both refuges, although there were differences in abundance between the sexes for interior and edge habitats and between habitat types. Bronzed Cowbirds responded differentially to host species playbacks based on suitability and abundance of the host species. The results …

Ethnobotanical History And Seed Oil Chemistry Of The Physic Nut, Jatropha Curcas, Nathan M. Leclear

Theses and Dissertations - UTB/UTPA

Jatropha curcas L., Euphorbiaceae, is a small tree native to the neotropics. Despite renewed economic interests in Physic Nut, mainly for biodiesel production, a comprehensive analysis of the ethnobotanical history of J. curcas is lacking. An account of the pre-Columbian neotropical distribution of this species and its historical uses are presented. Using capillary gas chromatography, studies were conducted to quantify the natural variation in seed oil content and fatty acid composition of the seed oil from several species of Jatropha, including assessment of how these parameters change during seed maturation. Natural variation in seed oil content was detected (F7,93 = …

Does The Manipulation Of Tail Position Facilitate Extinction Of Canine Phobic Behavior?, Rebecca A. Zarate

Theses and Dissertations - UTB/UTPA

The phobic behavior of interest is tail tucking which is indicative of submission. In this study the tail was physically manipulated by the use of a custom made harness to hold the tail up in a dominant position to ideally extinguish phobic behavior through reciprocal inhibition. The harness did not hold the tail up the entire duration of the interventions, although it still held the base of the tail up. The intervention did not appear to have an affect on the two of the five subjects. The three more phobic canines did display some behavioral changes, although the changes noticed …

Population Ecology And Reproductive Biology Of The Diamondback Watersnake, Nerodia Rhombifer (Serpentes: Colubridae), In Southernmost Texas, Ruben D. Zamora

Theses and Dissertations - UTB/UTPA

Nerodia rhombifer is a polytypic, semi-aquatic snake with a broad geographical distribution ranging from the American Midwest southward to Chiapas, Mexico. Although relatively abundant throughout much of its range, few ecological studies of the species have been conducted. This study provides basic population ecology information in a subtropical habitat. Population data were obtained in a mark-recapture study at Santa Ana National Wildlife Refuge, Hidalgo County, Texas, from August 1995 to December 1998. Specimens taken elsewhere in Hidalgo County provided information on the reproductive biology. This study provides the first absolute density estimates from anywhere within the species’ range. Quantitative information …

Built Environment: Does Geographical Proximity Play A Role In Exercise Frequency And Adherence?, Nancy Anzaldua

Theses and Dissertations - UTB/UTPA

Built environment has been identified as a factor affecting exercise adherence. The author conducted a cross-sectional descriptive study to examine the relationship of distance traveled and its relationship to frequency of exercise and level of adherence. Surveys with demographic and contextual information were collected from 260 participants. Demographic data was mapped using Geographic Information Systems software and data analyses were performed on geographical trends, participants' use facilities and participants' proximity to their respective place of exercise. Trends among participants across the various bands were determined. The author found strong support to show geographical proximity as an important factor in frequency …

Genetic And Phenotypic Characterization Of Plant Pathogen Inhibitory Streptomyces Isolates, Uylissa A. Rodriguez

Theses and Dissertations - UTB/UTPA

Streptomyces are Gram-positive, filamentous bacteria that are readily isolated from soil and produce diverse secondary metabolites such as pigments and antibiotics. A survey of indigenous soil microbes from Rio Grande Valley agricultural soils revealed several isolates with broad inhibitory abilities against a range of soil-borne plant pathogens. The goal of this study was to characterize eleven of these potential biocontrol isolates both biochemically and genetically. Nutrient utilization profiles, 16S rDNA sequencing, and the presence of genes involved in antibiotic biosynthesis pathways (strBl, strR, strF, strN, strS and KS) on plasmids or the chromosome were investigated. Nutrient utilization profiling revealed that …

The Influence Of Environmental Factors On The Activity And Movement Of Bufo Nebulifer (Coastal Plain Toad) In A Disturbed Area, Crystal Salinas

Theses and Dissertations - UTB/UTPA

Toads in the family Bufonidae are poorly studied in southern Texas. Bufo nebulifir, a native bufonid, has been studied in its northern and southern range limits (east Texas and northern Mexico). South Texas' sub-tropical climate could impact the length of the activity period for B. nebulifer in yet unrecorded ways. This study resolves whether environmental factors correlate to Bufo nebulifer's activity, presence, and movement, using a mark-recapture method. The study was conducted for one year during February 2008 to March 2009. Environmental factors, especially rainfall and temperature were significantly correlated (PB. nebulifer . The active period of B. …

Hispanic Youth Physical Activity Participation: A Study Of Psychological And Social Influence, Maria L. Trinidad

Theses and Dissertations - UTB/UTPA

This study seeks to identity barriers that influenced middle school students from engaging in daily physical activity at least 60 minutes outside of their physical education classes in the Rio Grande Valley. Statistical significance of the study will be determined at the 95% level of confidence. The researcher offers the null hypothesis of no difference between the doers and non-doers The participants of this study were 79 middle school students ages 12-15. The participants were given an open-ended questionnaire. Cross tabulation analyses was conducted to determine difference using the Mann-Whitney U Test. Data from the research questions was analyzed by …

Evaluation Of Streptomycetes For Biological Control Of Gummy Stem Blight Disease Of Cantaloupe, Shima Chaudhary

Theses and Dissertations - UTB/UTPA

Studies were conducted to evaluate the efficacy of Streptomyces isolates for the biological control of gummy stem blight (GSB) in cantaloupes (Cucumis melo var. ‘Primo’) in south Texas. Plants were monitored for seedling emergence, lesions, mortality and plant growth under laboratory, greenhouse and field conditions. Comparison of treatment groups indicated a significant reduction in plant mortality and enhanced growth of infected plants exposed to three Streptomyces isolates (MA1F4#2, WI1B#5, and MA2A4 #2), which appear to be most effective when used in combination. In all three experiments, GSB infection was associated with a significant reduction in reflectance of near-infrared wavelengths (700-1,100 …

Stress Responses To Salinity In A Native Fresh Water Snake (Nerodia Rhombifer), Joana A. Cordoba

Theses and Dissertations - UTB/UTPA

Salinity stress at 0 ppt, 9 ppt, 18 ppt, and 27 ppt was investigated in Nerodia rhombifer, a fresh water snake. The purpose of this study was to establish if exposure to salinity could elicit a hormonal response in the form of corticosterone. Salinity treatment 27 ppt was lethal for 50% of the snakes. Factors such as population and gender differences were not significant, p=0.748 and p=0.135, respectively. Exposure to the different salinities did not significantly affect the overall mass of the animal, p=0.951. A significant increase in circulating corticosterone was noted in salinity treatments 0 ppt and 18 ppt, …

Phenotypic And Genetic Differences In Soil Bacterial Communities Among Successional Stages, Rowena A. G. Hamlet

Theses and Dissertations - UTB/UTPA

The association between soil microbes and plants can influence plant growth and survival as well as alter soil microbial community dynamics. The purpose of this study was to determine how the length of this interaction between plants and bacteria affects the bacterial soil community structure. Soil microbial communities associated with plant communities at different successional stages at the Santa Ana National Wildlife Refuge were investigated. The study sites included three revegetated sites (4 months, 21 months, and 221 months since revegetation) and a control site (native brush, never revegetated). Five soil samples were randomly collected at each site. Soil microbial …

Searching Response Of A Wandering Spider To Potential Cues Associated With Lepidopteran Eggs, Rosa Isela Ruiz

Theses and Dissertations - UTB/UTPA

Cheiracanthium inclusum (Hentz), a wandering spider, has been frequently observed feeding on the eggs of Helicoverpa zea (Boddie), an important cotton pest. Wandering spiders are known to feed mainly on mobile prey, thus mechanisms used by these spiders to locate sessile prey remain understudied. Vibratory and visual are among the main cues used by spiders to identify prey. However, other sensory modalities such as chemoreception may be used but are poorly understood. This study investigated the types of cues utilized by C. inclusum to locate and identify H. zea eggs as prey. Results show that C. inclusum responds positively to …

Comparative Pollen Foraging Of Africanized And European Honeybees In A Non-Agricultural Environment, Ruben Ruiz

Theses and Dissertations - UTB/UTPA

With the advent of the Africanized honeybee, ways to differentiate it from the European honeybee have been greatly sought in attempts to better understand the role of Africanized bees in pollination. Pollen collecting strategies for both honeybee subspecies have been explored in attempts to exploit their pollinating capabilities. This project examined pollen collected by honeybees from feral and managed European and Africanized colonies in a relatively isolated site. Paired European and Africanized honeybee colonies were used to obtain pollen foragers. Through acetolysis (series acidified Acetic Anhydride washings); the collected pollen from the individual foragers was treated and observed with light …

Mercury Concentrations In South Texas Game Fishes, E. Anthony Reisinger

Theses and Dissertations - UTB/UTPA

Mercury (Hg) is one of the most ubiquitous and controversial metals in the world primarily due to the toxicity of the organic form of the metal, methylmercury (MeHg). MeHg is a neurotoxin at high levels, known to manifest its effects on humans primarily through consumption of certain fish and marine mammals, which tend to bioaccumulate MeHg in their tissues over time. Increased fish consumption and, thus, mercury intake in residents of coastal areas necessitates a better awareness of MeHg content in game fish species, thus the subject of this study.

Three hundred thirty-nine tissue samples were taken from 19 south …

Collection, Isolation And Evaluation Of Nitrogen Fixing Bacteria In The Rio Grande Valley Of Texas, Thomas M. Eubanks

Theses and Dissertations - UTB/UTPA

Isolation from local soil samples with Phaseolus vulgaris (L.) produced 20 samples from which pure cultures were obtained. A commercial strain of Rhizobium #132 was obtained from Becker Underwood and included as a standard in the experiment. The results demonstrated that a variety of infective and effective of strains of Rhizobium nodulating Phaseolus vulgaris (L.) exist in the native soils of the Rio Grande Valley of Texas. A cluster of effective bacteria was identified and can serve as a basis for recommendations to inoculant industry in the Valley. An isolate collection has been established to serve as a source of …

The Effects Physical Activity Has On The Menstrual Cycle Characteristics Between Two Groups Of High School Athletes And One Group Of High School Non-Athletes, Yolanda D. Robinson

Theses and Dissertations - UTB/UTPA

The purpose of this study was to assess and compare the menstrual cycle characteristics between two groups of high school athletes and one group of high school non-athletes. The study consisted of 30 high school females from Donna High School. The participants consisted of ten female basketball athletes from the Donna High School Basketball Team (14.5 ± 4.5 years), ten female volleyball athletes from the Donna High School Volleyball Team (14.5 ± 4.5 years) and ten females (14.5 ± 4.5 years) that were randomly picked out of the general female population of the Donna High School that do not participate …

Use Of Pedometers To Promote Improvement In Selected Physiological Measurements In An Older Female Mexican American Population, Zasha Romero

Theses and Dissertations - UTB/UTPA

The problem of this study was to determine if pedometers promoted daily walking exercise reflected by changes on selected physiological measurements in older Mexican American females. Significance in the study was determined at the 95% level of confidence. The researcher offered the null hypothesis of no difference in results from the pretest to the posttest in both the control and treatment groups for the selected physiological measurements. The subjects of this study were 55 Mexican-American females ages 60 to 75. The subjects were randomly assigned to a treatment or control group. An analysis of covariance (ANCOVA) method was used to …

Breeding Distribution And Habitat Use Of Audubon's Oriole In The Lower Rio Grande Valley Of Texas, Steven Gerald Monk

Theses and Dissertations - UTB/UTPA

Audubon's Oriole ( Icterus graduacauda ) was known historically throughout the Lower Rio Grande Valley (LRGV) of Texas, but its breeding range has now declined to mainly riparian habitat in Starr County. Habitat loss, degradation, and fragmentation, and brood parasitism by Bronzed Cowbirds ( Molothrus aeneus ) are likely causes of this decline. Habitat patches where Audubon's Orioles were present were larger, with a larger vertical range of canopy, greater vegetation volume, greater richness of bird and woody plant species, less local deforestation, and less local habitat fragmentation than where Audubon's Orioles were absent. Bronzed Cowbirds showed no numeric correlation …

Chorionic Morphology Of Mayfly (Ephemeroptera) Eggs Of The Lower Rio Grande Valley, Maria D. De Leon

Theses and Dissertations - UTB/UTPA

External egg morphology of ten species of Lower Rio Grande Valley (LRGV) mayflies are compared using scanning electron microscopy (SEM) and a taxonomic key to the eggs is provided. The eggs of five species are described here for the first time. Preserved female adults or subadults were critical-point dried using liquid CO2 . The eggs were removed and placed on metal stubs for sputter coating with gold/palladium. The coated eggs were then observed and photographed by SEM. The morphological features described were the chorionic sculpturing, polar caps, accessory attachment structures, and micropyles. This is the first mayfly egg comparison and …

Effects Of Ethanol On The Toxicity And Metabolism Of Acetonitrile And Acrylonitrile, Nancy Ochoa-Garza

Theses and Dissertations - UTB/UTPA

This study examined the effects of ethanol on the toxicities and metabolism of two aliphatic nitriles: acetonitrile and acrylonitrile (one unsaturated and one saturated aliphatic nitrile, respectively) in male Sprague-Dawley rats at four different time intervals. Toxicity signs were apparent in all animals given the nitrile dosage, but those treated with ethanol dosages showed signs of toxicity earlier than those treated with glucose dosages. Both of the nitrites were metabolized to cyanide and thiocyanate. The concentration levels of each metabolite was apparent at 2 and 3 g/kg ethanol dosage for acetonitrile and 3 and 4.5 g/kg ethanol dosage for acrylonitrile …

Effect Of Guanosine Tetraphosphate On Growth Rate And Stable Rna Synthesis In Escherichia Coli, Heather Anne Quintanilla

Theses and Dissertations - UTB/UTPA

Guanosine tetraphosphate (ppGpp) is a good candidate for a stable RNA synthesis regulator at different growth rates because: high ppGpp levels present during the stringent response are known to inhibit stable RNA synthesis, and there is an inverse correlation between ppGpp concentration and stable RNA synthesis at different growth rates. A system was constructed allowing the user to control intracellular ppGpp levels within the range characteristic of exponentially growing strains, while not allowing cells to adjust ppGpp in response to environmental changes. E. coli strains were transformed with a plasmid containing a truncated relA allele to provide ppGpp. Results show …

Ocelot Distribution In The Lower Rio Grande Valley National Wildlife Refuge, Kevin James Shinn

Theses and Dissertations - UTB/UTPA

Weaver hair-snaring surveys were conducted at 125 sites on 27 Refuge tracts to obtain information about the distribution and population status of the endangered ocelot ( Leopardus pardalis ) in the Lower Rio Grande Valley National Wildlife Refuge. The surveys resulted in 33.6% of the pads “hit”, including 8 by ocelot and 29 by bobcat. There was no significant difference in the number of ocelot hits between warm and cool seasons or between the sexes. Preferred habitat consists of dense thornscrub brush. Four species, snake-eyes, granjeno, honey mesquite, and colima comprise 50% or more of the total cover at each …

Identification Of A Genetic Locus Involved In Ppgpp Metabolism In Escherichia Coli, Roxanne Enid Garza

Theses and Dissertations - UTB/UTPA

Two genes involved in the metabolism of ppGpp are relA and spoT . A relX mutant has altered ppGpp levels, so relX may be a regulator of the RelA or SpoT enzymes. The growth of the relX mutant has been reported to be both temperature and leucine sensitive. It was discovered in this work that this relX mutant is not temperature sensitive, however it is leucine sensitive. The original goal was to study effects of the relX gene on ppGpp metabolism. During the process of mapping the relX gene, it was discovered that the leucine sensitivity was caused by some …

Detection Of The Phototoxic Dye Phloxine B In Anastrepha Ludens (Loew) (Diptera: Tephritidae), Apis Mellifera Linnaeus (Hymenoptera: Apidae) And Honey, Aleena M. Tarshis Moreno

Theses and Dissertations - UTB/UTPA

A spectrophotometric method for detection of phloxine B, a phototoxic dye proposed as a replacement for malathion bait sprays, in extracted tissues of Anastrepha ludens, Apis mellifera and in honey was developed. Dye detection was increased with a pH change from 6 to 13.7 in tissues or from 3.7 to 8 in honey with 2% sodium hydroxide. An LC 50 of 29.62 ppm phloxine B in 30% sucrose was obtained by feeding honey bees. A predictive model for dye in insect tissues and honey was developed and shown to be 89–92% effective. This study provides a forensic approach to determine …

Comparison Of Rodent Communities Of Native Brushland, Replanted, And Secondary Succession Sites In The Lower Rio Grande Valley Of Texas, Mitchell Allen Sternberg

Theses and Dissertations - UTB/UTPA

I compared small mammal communities between mature brushlands, replanted brushlands, and secondary succession sites from November 1998 to December 1999 to evaluate revegetation efforts in the Lower Rio Grande Valley of Texas. I determined rodent community characteristics of the three habitat types. The mature brushland and replanted habitats had similar species diversities and both were significantly higher than the secondary succession habitat. Species diversity was highest at the replanted edge grid during Winter. The current replanting method provides a more diverse rodent community than does natural succession from fallow fields. Wildlife monitoring should be extended to other taxonomic guilds so …

Patterns Of Avian Productivity Indices At Santa Ana National Wildlife Refuge (1995–1999), Tina Louise Gallegos

Theses and Dissertations - UTB/UTPA

I examined demographic parameters at Santa Ana National Wildlife Refuge, 1995–1999 utilizing Monitoring Avian Productivity and Survivorship protocol. The Olive Sparrow was the species most frequently captured. The capture rate of adult and young birds remained fairly steady over the years and no significant linear trends were observed. Productivity was highest in 1997, which influenced the number of adults captured in 1998, and was significantly related to annual rainfall. Mean total capture rates were higher at the Highland station than the Resaca station. Demographic comparisons between mist nets and point counts were variable, suggesting that both sampling techniques have their …

Comparative Phenology Of Acacia Berlandieri, A. Minuata, A. Rigidula, A. Schaffneri, And Chloroleucon Ebano In The Lower Rio Grande Valley Of Texas, Melissa R. Eddy

Theses and Dissertations - UTB/UTPA

A phenological study of Acacia berlandieri, A. minuata, A. rigidula, A. schaffneri, and Chloroleucon ebano was conducted at three sites in the lower Rio Grande Valley of Texas from July 1998 to August 1999. Flowering in Acacia species occurred between January and April 1999, and was influenced by precipitation only in A. minuata . The timing of flowering appears to be influenced by the amount of time needed for fruit maturation. Precipitation, photoperiod, and temperature influenced the timing of fruiting in all species except A. berlandieri . Shoot elongation and leaf maturation in Acacia species were positively correlated with …