Life Sciences Commons^™

After More Than A Decade Of Soil Moisture Deficit, Tropical Rainforest Trees Maintain Photosynthetic Capacity, Despite Increased Leaf Respiration, Lucy Rowland, Raquel L. Lobo-Do-Vale, Bradley O. Christoffersen, Eliane A. Melém, Bart Kruijt, Steel S. Vasconcelos, Tomas Domingues, Oliver J. Binks, Alex A. R. Oliveira, Daniel Metcalfe

Biology Faculty Publications and Presentations

Determining climate change feedbacks from tropical rainforests requires an understanding of how carbon gain through photosynthesis and loss through respiration will be altered. One of the key changes that tropical rainforests may experience under future climate change scenarios is reduced soil moisture availability. In this study we examine if and how both leaf photosynthesis and leaf dark respiration acclimate following more than 12 years of experimental soil moisture deficit, via a through-fall exclusion experiment (TFE) in an eastern Amazonian rainforest. We find that experimentally drought-stressed trees and taxa maintain the same maximum leaf photosynthetic capacity as trees in corresponding control …

Examination Of The Chagas Disease Vector, Triatoma Gerstackeri, In The Lower Rio Grande Valley, Alfredo Flores

Theses and Dissertations

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, which is carried by an insect vector of the family Reduviidae, and of the subfamily Triatomina. The species Triatoma gerstaeckeri is identified as the primary vector of T. cruzi within the Rio Grande Valley. Species of Triatoma gerstaeckeri were trapped in La Sal del Rey National Refuge in 2012 and 2013.

Data indicates a seasonal dispersal pattern of activity for T. gerstaeckeri. Optimal time of capture was between 1-2 hours after sunset. Different methods were utilized to determine the best combination of lures. Results indicate that the UV-light alone is …

Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado

Theses and Dissertations

Seagrass beds are pivotal in the functioning of coastal ecosystems in terms of productivity, organic matter turnover and nutrient cycling. Aiming to document decay and nitrogen (N) dynamics of turtle grass (Thalassia testudinum) in a subtropical estuarine system, decomposition patterns of leaves and rhizomes were characterized and compared. Nitrogen usage during decomposition of tissues, and of live tissues and epiphytes growing on live leaves, was also quantified and compared. Stable isotope ratios allowed tracing N within the seagrass bed, following N incorporation into seagrass tissues from the surrounding media (water, sediment). Leaves had a higher N content and decomposed at …

Activation Of Microglia In The Rotenone Lymnaea Stagnalis Model Of Parkinson's Disease, Xiomara Galvan

Theses and Dissertations

Parkinson’s disease (PD) is the most common irreversible neurodegenerative movement disorder affecting approximately ten million people worldwide. In the central nervous system (CNS), PD is known by the selective loss of Dopamine (DA) cells of the substantia nigra pars compacta. Although the disease has been very widely studied, the underlying mechanisms are not yet understood. Several hypotheses have arisen as result of injury of the mitochondria, some experiments include microglia activation, microtubule damage, and reactive oxidative species, which all result in the death of DA cells. The theory of microglia activation upon inflammation was explored in this study. Using the …

Validating Side Scan Sonar As A Fish Survey Tool, Michael A. Bollinger

Theses and Dissertations

Hydroacoustic methods can be used to answer a variety of questions regarding fish populations and behavior. In this study, side scan sonar methodology was developed to quantify abundance and biomass and compared to established visual observation methods on SCUBA over artificial reef structures in the western Gulf of Mexico. Side scan sonar methods were equivalent to SCUBA surveys for measuring fish abundance over the same reef areas, however, abundances were significantly higher when the larger area sampled by side scan was utilized. Side scan sonar methods were also more time efficient than SCUBA, ROV and long line fishing methods (66.7%, …

Comparing Reproductive Capacity Of Nearshore And Offshore Red Snapper, Lutjanus Campechanus, On Artificial Reefs In The Western Gulf Of Mexico, Ricky J. Alexander

Theses and Dissertations

Red snapper collected quarterly from four artificial reefs in south Texas were examined to compare total length, total weight, age, and the proportion of male to female red snapper, calculate gonadosomatic index values, batch fecundity, annual spawning frequency, and annual fecundity, and estimate size and age at maturity. Spawning occurred from April to September, with most active spawning observed in June (58%). Despite larger red snapper producing more eggs, and fish being larger offshore, most active spawning (68%) and egg production (74%) was observed nearshore. Female red snapper reached 50% maturity (L50) between 350-550 mm, and L75 by 600 mm. …

Balanus Eburneus (Crustacea: Cirripedia) As A Potential Indicator Of Estuarine System Recovery In South Texas: A Study Of Recruitment, Growth And Stable Isotopes, Crystal Martinez

Theses and Dissertations

Population characteristics of the barnacle Balanus eburneus were analyzed with the purpose of exploring its potential use as a discriminating indicator among sites exhibiting different disturbances or stages of recovery. The study was conducted from May 2012 to May 2013 at four estuaries in the Lower Laguna Madre, TX including a) Bahia Grande, currently under restoration and divided into Bahia Grande North and Bahia Grande South, b) San Martin Lake, which receives runoff water and c) South Bay, a relatively undisturbed reference estuary. In general, similar barnacle recruitment and growth trends in Bahia Grande South and South Bay were explained …

Effects Of Shrub Encroachment And Removal On South Texas Coastal Prairie Flora, Parker Alex Watson

Theses and Dissertations

Watson, Parker Alex, Effects of shrub encroachment and removal on South Texas coastal prairie flora. Master of Science, December, 2015. 60 pages, 14 tables, 11 figures, 47 references, 5 appendices. Native-invasive honey mesquite (Prosopis glandulosa) and huisache (Acacia farnesiana) are aggressively encroaching onto South Texas coastal prairies, outcompeting Gulf cordgrass (Spartina spartinae) and associated prairie vegetation with potential legacy effects on the landscape. To measure conditions in the presence of shrubs, data loggers were installed for 16 mos in shrub understories and grass cover to monitor light, soil and air temperatures. Vegetation and canopy surveys were also conducted to evaluate …

Effects Of Control Release Fertilizers On Nutrient Leaching, Palm Growth And Production Cost, Pushpa Soti, Angie Fleurissaint, Stewart Reed, Krish Jayachandran

Biology Faculty Publications and Presentations

Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis) and Queen (Syagrus romanzoffiana). We compared Nutri-Pak (12-4-12 controlled release packet) and Harrell’s (12-4-12 controlled release polymer coated urea) against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash), the most commonly used palm fertilizer in South Florida. Plants were grown in 25 cm (11 L) pots under 70% shade, watered weekly, with pest and weed control done as required. Plant growth parameters: number of leaves, leaf length …

Impact Of The Biological Control Agent Tetramesa Romana (Hymenoptera: Eurytomidae) On Arundo Donax (Poaceae: Arundinoideae) Along The Rio Grande River In Texas, John A. Goolsby, Patrick J. Moran, Alexis Racelis, Kenneth R. Summy, Maricela Martinez Jimenez, Ronald D. Lacewell

Biology Faculty Publications and Presentations

Five years post-release of the arundo gall wasp, Tetramesa romana, into the riparian habitats of the lower Rio Grande River, changes in the health of the invasive weed, Arundo donax, or giant reed, have been documented. These changes in plant attributes are fairly consistent along the study area of 558 river miles between Del Rio and Brownsville, TX, and support the hypothesis that the arundo wasp has had a significant impact as a biological control agent. Plant attributes were measured prior to release in 10 quadrats at each of 10 field sites in 2007, and measured again …

Ca2+/Calmodulin Regulates Kvβ1.1-Mediated Inactivation Of Voltage-Gated K+ Channels, Sandip M. Swain, Nirakar Sahoo, Sophie Dennhardt, Roland Schönherr, Stefan H. Heinemann

Biology Faculty Publications and Presentations

A-type K+ channels open on membrane depolarization and undergo subsequent rapid inactivation such that they are ideally suited for fine-tuning the electrical signaling in neurons and muscle cells. Channel inactivation mostly follows the so-called ball-and-chain mechanism, in which the N-terminal structures of either the K+ channel’s α or β subunits occlude the channel pore entry facing the cytosol. Inactivation of Kv1.1 and Kv1.4 channels induced by Kvβ1.1 subunits is profoundly decelerated in response to a rise in the intracellular Ca2+ concentration, thus making the affected channel complexes negative feedback regulators to limit neuronal overexcitation. With electrophysiological and biochemical experiments we …

A Bomb Set To Drop: Parthenogenetic Marmorkrebs For Sale In Ireland, A European Location Without Non-Indigenous Crayfish, Zen Faulkes

Biology Faculty Publications and Presentations

Ireland is one of the few locations in Europe where non-indigenous North American crayfish species have not been introduced, and is a refuge for endangered white-clawed crayfish, Austropotamobius pallipes (Lereboullet, 1858). The parthenogenetic crayfish species Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870), is sold in the pet trade in Ireland within the recorded range of A. pallipes. Marmorkrebs risk being introduced into Irish waters, where they could threaten A. pallipes populations, particularly as a vector for crayfish plague.

Analysis Of Variables Related To Corridor Use By Ocelots And Bobcats In South Texas, Sarah E. Nordlof

Theses and Dissertations - UTB/UTPA

Biologists estimate that less than 50 endangered ocelots (Leopardus pardalis) remain in the United States, restricted to two small populations in Cameron and Willacy Counties located in deep south Texas. Conversely, bobcats (Lynx rufus) are abundant in south Texas; however, two of the biggest threats to both species are vehicle collisions and habitat fragmentation. To mitigate these threats, the installation of wildlife crossings has been proposed to decrease the number of road mortalities, and wildlife corridors have been suggested as a useful tool for providing increased habitat connectivity. However, research on ocelot use of corridors and wildlife crossings in Texas …

Loss Of Mitochondrial Dna Causes Decreased Cell Viability, Alan M. Herrera

Theses and Dissertations - UTB/UTPA

Mitochondria are an organellar network involved in cellular bioenergetics and apoptosis, and dynamically balance their organization between fusion and fission events. Mitochondrial DNA (mtDNA) and nuclear DNA combine to encode polypeptides for the complexes of oxidative phosphorylation (OXPHOS) in the mitochondrial inner membrane, which generate a transmembrane potential (ΔΨm) to synthesize ATP. Loss of ΔΨm causes mitochondrial fission, which appears to be associated with the progression of apoptosis, a critical cell death mechanism that allows tissue homeostasis, developmental sculpturing, and the removal of unwanted cells. Using cultured human cell models of decreased ΔΨm (both genetic mtDNA-depleted ρ 0 and pharmacological …

Ecosystem Services Of Urban Trees And The Impacts Of Urbanization, Jorge E. Cantu

Theses and Dissertations - UTB/UTPA

The University of Texas- Pan American has conducted a complete survey of campus trees in partial fulfillment of the requirements for membership in the International Society of Arboriculture Designation of Tree Campus USA. This tree inventory was accomplished with the help of students whom were trained by faculty and foresters. Other than the completion of the tree inventory, this thesis had two main goals; 1) valuate the ecosystem services provided by campus trees 2) create a unique service learning project that other institutions can model. According to our calculations, the trees on campus have sequestered 568,652 kg of CO2, avoided …

Exploration Of Nickel Tolerance And Hyperaccumulation In Arabidopsis Thaliana Transformed With Streptanthus Polygaloides Metal Tolerance Protein 1 (Spmtp1) Cdna, Madeleine K. Sano

Theses and Dissertations - UTB/UTPA

This study evaluated the role of hyperaccumulator S. polygaloides Metal Tolerance Protein 1 (SpMTP1) in conferring Ni tolerance and accumulation in the non-accumulator Arabidopsis thaliana. Analysis for Ni content in transgenic Arabidopsis transformed with SpMTP1, following a 12-day treatment of 100 µM Ni, showed a significant increase in Ni concentration in comparison to the wild-type Arabidopsis and empty vector transformed plants. Exposure of transgenic Arabidopsis to nickel also resulted in a coordinated increase of antioxidant enzyme (superoxide dismutase, glutathione reductase, and catalase) activities in the transgenic Arabidopsis, suggesting that increased activities of these oxidative stress response (OSR) proteins may be …

Infection Rates And Distribution Of Trypanosoma Cruzi In Triatomine Insects From Several Public Parks Of Starr, Hidalgo And Cameron Counties, Carlos Guzman Jr.

Theses and Dissertations - UTB/UTPA

Chagas disease is caused by the protozoan Trypanosoma cruzi and is a major public health concern in many areas of the world, including the United States. The disease is transmitted by insect vectors known as kissing bugs from the subfamily Triatominae. While the majority of studies focus on domestic and peri-domestic collections, this study collected insect vectors from state parks in the Lower Rio Grande Valley. PCR analysis was done to obtain infection rates for collected insects, and a morphological examination was done to check insects for gender. In total 18 insects were captured with 12 of the captured insects …

Characterization Of Oxidative Stress Response Proteins In Metal-Tolerant And Metal-Sensitive Brassicaceae Plant Species, Luis M. De Santiago

Theses and Dissertations - UTB/UTPA

In this study the expression of oxidative stress response (OSR) proteins in nonaccumulator and hyperaccumulator plant species of the Brassicaceae family were characterized. Oxidative stress was induced via nickel treatment and proteins were characterized through western blotting and image analysis. Statistical analysis indicated that the nonaccumulator species Arabidopsis thaliana significantly decreased catalase (CAT), glutathione reductase (GR), copper/zinc-dependent superoxide dismutase (Cu/ZnSOD), iron-dependent SOD (FeSOD), manganese-dependent SOD (MnSOD) and metal tolerance protein 1 (MPT1) expression in response to Ni-treatment. The hyperaccumulator species Thlaspi montanum variety montanum displayed either no significant change or a significant increase in OSR regulation following Ni-treatment with the …

Species Identification And Habitat Assessment Of The South Texas Siren, Taylor C. Lafortune

Theses and Dissertations - UTB/UTPA

At least one species of siren is endemic to the Rio Grande Valley of Texas, yet very little is known about the populations of the region. Texas Parks and Wildlife refers to the populations of Siren spp. in South Texas as the “South Texas siren (large form Siren sp. 1),” and recognizes these populations as a threatened species, yet their current population status remains unclear. The species identification of the South Texas siren has been hampered by similarity in morphology across species, and by the lack of complete siren genetic sequences in the NCBI GenBank database. In addition to species …

Development Of A Dna Barcoding Reference Library For Identification Of Medicinal Plant Materials Used In The Rio Grande Valley Of Texas: A Representative Case Study Using Arnica (Asteraceae), Hector G. Aguilar De Alba

Theses and Dissertations - UTB/UTPA

DNA barcoding is a technique that uses a short DNA fragment to identify a specimen to the species level. This technique is essential in situations where a lack of distinguishing morphological characteristics makes identification impossible. In the Río Grande Valley a variety of herbal supplements are cheap, readily available and sold as “Arnica” with no information to identify the contents. The appearance of dried and shredded material suggests that a variety of plant species are involved, belonging to the family Asteraceae. Arnica montana, also part of Asteraceae, is found in Europe and has anti-inflammatory properties used to externally treat bruises …

Functional Analysis Of The Mms19 Gene In Carica Papaya, Jorge A. Trujillo

Theses and Dissertations - UTB/UTPA

All organisms face DNA-damaging radiation in the form of UV light and must have mechanisms to repair or undo damage. Plants being stationary organisms must cope with damaging UV rays in a molecular fashion and so have developed many forms of resistance. MMS19 is implicated in DNA repair indirectly as a nuclear encoded gene that binds onto protein assembly complexes in the cytosol. A mutant within the SunUp variety of Carica papaya has a large deletion for MMS19 and presents a diminutive phenotype. Deficient DNA repair mechanisms will shunt cells out of the natural cell cycle and reduce cell proliferation …

Restoring Semi-Arid Thornscrub Forests: Seeding Growth And Survival In Response To Shelter Tubes, Grass-Specific Herbicide, And Herbivore Exclosures, Krysten Noelle Dick

Theses and Dissertations - UTB/UTPA

This thesis is a compilation of two studies, which I have called ‘chapters.’ The first chapter, “Restoring Semi-Arid Thornscrub Forests: Seedling Growth and Survival in Response to Shelter Tubes, Grass-Specific Herbicide, and Herbivore Exclosures,” was a large study involving multiple techniques used to improve revegetation success, and the second chapter, “Shelter Tube Effects on Microclimate and Seedling Growth in Semi-arid Thornscrub Forests,” focused on the use of shelter tubes in semi-arid forest revegetation. These studies were concurrent evaluations of restoration efforts in thornscrub forests of South Texas. Revegetation is a common effort used to restore forest ecosystems that have been …

Biological Flora Of Coastal Dunes And Wetlands: Borrichia Frutescens (L.) Dc., Robert I. Lonard, Frank W. Judd, Richard Stalter

Biology Faculty Publications and Presentations

Borrichia frutescens (L.) DC. is a New World warm-temperate, subtropical, and tropical zone, perennial subshrub that is an important species in hypersaline coastal sites. Also known as sea ox-eye, it tolerates salinities ranging from less than 20 ppt to 130 ppt. It occurs in substrates low in organic matter and deficient in nitrogen, phosphorus, and potassium. Nearly all reproduction is vegetative from an extensive rhizome system. Populations of this species recover quickly after coverage by wrack. Stands of B. frutescens often dominate the landward border of salt marshes.

Correlation Of Amyloid Beta And Spatial Learning And Memory Deficits On A Thy1-App Mouse Model For Alzheimer's Disease, Amber Lynn Betz

Theses and Dissertations - UTB/UTPA

The McGill-Thy1 APP mouse is a triple transgenic model of Alzheimer disease, which has the mutant amyloid precursor protein to synergistically over-produce amyloid beta plaques. These mice exhibit visuo-spatial learning impairment at 3 months of age and memory impairment at 10-13 months of age in the Morris water maze. To extend these findings mice at 3, 5, and 7 months of age were tested on the Barnes maze. Non-Transgenic and Transgenic mice showed improvement during acquisition. However, 3 month and 5 month McGill Thy1- APP mice showed impaired acquisition learning while 7 month showed a learning and memory deficit compared …

Characterization Of Continuously Oscillating Neurons (Cons) Of The Medial Septum Of Rats, Nadia Noel Carreon

Theses and Dissertations - UTB/UTPA

Theta oscillation is the largest extracellular synchronous signal that can be recorded from the mammalian brain. It is known to influence information retention in the hippocampus, which plays a key role in declarative memory, recognition memory, working memory, and spatial memory. The theta oscillation field frequency is between 3 and 12 Hz and is present during exploratory behavior and sleep in rodents. Theta rhythm in the hippocampus is postulated to be produced by the rhythmical activity of pacemaking cells in the medial septumvertical limb of the diagonal band of Broca (MS-vDBB). Previous work in our laboratory demonstrated the existence of …

Restoration Strategies To Migrate Shrub Encroachment Into Coastal Prairies, Erick Mark Verderber

Theses and Dissertations - UTB/UTPA

Shrub encroachment into grasslands is a phenomenon facilitated by fire suppression, climate warming, and overgrazing of grasses by cattle, and if left unmanaged, can alter ecosystem structure and function. In this study, I compare the effectiveness and cost/benefit of various restoration strategies (prescribed fire, mechanical, and chemical) used singly and in different combinations at decreasing two shrubs, honey mesquite (Prosopis glandulosa Torr.) and huisache (Acacia farnesiana (L.) Willd.), and promoting growth and survival of gulf cordgrass (Spartina spartinae (Trin.) Merr. ex Hitchc.), the dominant coastal prairie grass within the Laguna Atascosa National Wildlife Refuge-Bahia Grande Unit in deep south Texas. …

Differential Gene Expression Between Two Developmental Stages Of The Gené'S Organ In The Cattle Fever Tick, Rhipicephalus (Boophilus) Microplus, Jason P. Tidwell

Theses and Dissertations - UTB/UTPA

The southern cattle fever tick (SCFT), Rhipicephalus microplus, is considered the most economically important ectoparasite of livestock worldwide and ranks sixth among the most pesticide resistant arthropods globally. This single-host hard tick is a vector of the infectious agents causing bovine babesiosis and anaplasmosis. The estimated impact of these SCFT-borne diseases on the livestock industry in the world is $7 billion annually. This project focuses on the Gené’s organ and addresses the need to identify novel targets that can serve as the basis for sustainable SCFT control strategies. Wax secreted by the Gené’s organ protects tick eggs from desiccation, bacterial …

The Role Of Oxidative Stress In The Rotenone Model Lymnaea Stagnalis, Homero L. Cantu

Theses and Dissertations - UTB/UTPA

Parkinson’s disease (PD) is the most common neurodegenerative movement disorder, characterized by progressive depletion of dopamine (DA). Rotenone, a common pesticide, can induce PD like symptoms in animal models. The goal of this thesis is to quantify the levels and effects of reactive oxygen species (ROS) in brain tissue of the common neurobiological gastropod model, Lymnaea stagnalis, after treatment with Rotenone. The results show that rotenone causes a behavioral deficit and increases ROS production, especially superoxide. Furthermore, glutathione was depleted and protein carbonyl formation increased. These results are consistent with findings in human PD and the high levels of ROS …

Animal Habitat Utilization And The Impacts Of Small-Scale Disturbances On Vegetation Within Larch Forests In Northeastern Siberia, Aaron Phillip White

Theses and Dissertations - UTB/UTPA

Boreal forests support a variety of animals distributed across a matrix of habitat patches including forests of different ages and stand densities. These forests occur at high latitudes where cold and moist conditions favor ground layer dominance by mosses and slow decomposition rates, resulting in a thick soil organic layer (SOL) comprised primarily of decomposing mosses and roots. However, limited information is available on how animal use varies across habitat types in northeastern Siberia. Boreal forests of this region are unique because they are comprised of a single deciduous conifer, Cajander larch (Larix cajanderi). These forests also occur on a …

Attraction, Repellence, And Predation: Role Of Companion Plants In Regulating Myzus Persicae (Sulzer) (Hemiptera: Aphidae) In Organic Kale Systems Of South Texas, Carlos R. Moreno, Alexis Racelis

Biology Faculty Publications and Presentations

Annual outbreaks of green peach aphid, Myzus persicae (Sulzer), limit commercial production of brassica crops, especially in organic systems in subtropical areas such as South Texas. We assessed the influence of companion plants that emit attractant, repellent, and natural enemy-attractant stimuli (i.e., insectary plants) on abundance of green peach aphid in organic kale (Brassica oleracaea L. var. acephala) fields in South Texas. We also monitored the assemblage of arthropod predators and parasitoids on kale and evaluated the response of numerically dominant species to companion plants. Indian mustard (Brassica juncea (L.) Vassiliĭ Matveievitch Czernajew; attractant), dill (Anethum graveolens L.; repellent), fennel …