Research Fields

Research Fields

Aquatic Ecology

Christopher Taylor, Ph.D.

Research Interests: Aquatic Ecology, Ichthyology, Biogeography, Conservation

My general approach to research is based on the fact that ecological systems are highly variable in space and time. Thus, I use a diverse set of quantitative tools and experimental designs depending upon the particular question being asked. My research focus generally centers on how fish species and assemblages respond to disturbances. Of particular interest to me are how modified flow regimes and habit fragmentation threaten freshwater bloodiest globally and affect native communities at varying spatial and temporal scales.


Bacterial Genetics and Pathogenesis

Daniele Provenzano, Ph.D.

Research Interests: Vibrio cholerae, Type VI Secretion System (T6SS), intra- and interspecies competition, host-pathogen interactions, HGT (horizontal gene transfer).

Vibrio cholerae is the causative agent of cholera a devastating and potentially lethal form of diarrhea that persists as a significant cause of morbidity and mortality in the developing world. While only a subset of V. cholerae strains encode genes for the virulence factors Cholera Toxin (CT) and Toxin-Coregulated Pius (TCP) required for pandemic spread, all cholera bacteria and 25% of all Proteobacteria harbor genes coding a type VI secretion system (T6SS). T6SS gene products assemble into a dynamic molecular puncturing device in the cysts of bacteria to deliver defector molecules (toxins) into adjacent cells. Three effector molecules have been identified in V. cholerae along with cognate immunity proteins that protect kin bacteria from T6SS-mediated killing. Effector/immunity pairs appear to be horizontally mobilized within otherwise highly conserved T6SS gene clusters. Examination of Vibrio cholera=== strains endemic to the lower Rio Grande Delta led to the discovery of a wide range of effector/immunity pair alleles indicating that, in addition to interspecies competition, cholera bacteria also engage their T6SS in interspecies competition. T6SS-mediated interspecies competition is linked to V. cholerae’s ability to colonize the human host because nearly all strains that harbor CT and TCP (which reside on horizontally mobilized genetic elements CT-phage and VPI respectively) possess the same T6SS effector/immunity alleles. Characterization of novel episomal genetic elements and whole genome sequence data mining of V. cholerae strains endemic to the lower Rio Grande Delta as well as explorations of applications for therapeutic intervention strategies based on these T6SS discoveries are on-going.


Behavioral Ecology

Karl Berg, Ph.D.

Research Interests: Ornithology, behavioral ecology, acoustic communication, evolutionary developmental psychobiology, conservation biology.

Vocal imitation is a complex social behavior required for spoken language, but also found in select groups of mammals and birds. Parrots are among the most prolific of vocal linguists, but have been aloof in nature. How does their bizarre ability to mimic human speech patterns in captivity benefit individuals in nature? Current work addresses such questions in a wild parrot population that has been meticulously marked and studied for decades. Social environment can have a profound influence on early cognitive foundations, but this depends on when sensory abilities emerge in juveniles and the types of social stimuli available. Objectives are to: 1) quantify natural variation in a suite of early developmental milestones with links to learning and cognition; 2) Understand how social environment interacts with endocrine physiology to produce behavioral complexity; 3) Determine lasting effects of early developmental differences on adult traits including survival and reproductive success; 4) Broaden our phylogenetic perspective of developmental psychobiology by studying other taxa, including an endangered parrot species that ranges freely on the Brownsville campus and elsewhere in Rio Grande Valley.


Cell Biology

Megan Keniry, Ph.D.

Research Interests: Signal transaction, cell cycle, PIKE pathway.

Cellular growth and survival require the systematic coordination of signaling networks that direct gene expression, cell cycle, growth, polarity, motility, metabolism and cellular identity. My laboratory investigates signal transaction events on the phosphate 3 incase (PIKE) pathway with a focus on transcriptional outputs. PIKE has global effects on cellular signal transaction by increasing the concentration of the lipid second messenger phosphate 3,4 ,5 pyrophosphate (PIP). This lipid activates proteins that promote cellular growth and survival. The PIKE pathway is almost universally altered in cancer as well as diabetes. In cancer, PIKE output is increased, whereas in diabetes cells lose numerous PIKE outputs. The b-ZIP transcription factor NFL was recently discovered as a novel regulator of PIKE transcriptional output in cancer. NFL is highly expressed in poor prognosis cancers and promotes cancer cell survival. Research in my laboratory is focused at delineating how NFL contributes to poor prognosis in cancer by identifying signaling pathways and cellular processes that are impacted by this factor. Current laboratory projects include: (1) Investigating transcriptional outputs of NFL on the PIKE pathway, in cancer and beyond; (2) Examining regulatory mechanisms


Cellular Physiology - Mitochondria and Cellular Mechanisms

Robert Gilkerson, Ph.D.

Research Interests: Mitochondria genetics, cellular signaling.

Mitochondria are a dynamic organelle network for cellular convergences, which is integrated into crucial processes such as cellular signaling, metabolic regulation, and apoptosis. Mitochondria DNA (mtDNA) is a crucial participant in cellular homeostasis, and is maintained throughout the organelle network in assemblies called nucleoids. Mitochondria dysfunction, particularly the loss of mtDNA, is emerging as a molecular feature of a wide range of diseases, including diabetes, aging, autism, cardiovascular disease, and neurodegeneration. The research seeks to explore basic mechanisms of mtDNA maintenance and mitochondrial function and their role in human health and disease. Mitochondria network (red) of a human osteosarcoma cell. Tubulin cytoskeleton labeled in green.


Developmental Entomology

Matthew Terry, Ph.D.

Research Interests: Phylogenetics. Systematics (particularly of aquatic insects)R Evolution of Arthropod Appendages Evolutionary Developmental Biology HOX Gene Evolution and Diversity among Arthropods Molecular Evolution.

Focuses on the evolution and development of morphological diversity in arthropods, with a focus on hexapods (insects). Arthropods are, in many ways, an ideal group to work with when addressing questions involving the origins of morphological diversity and novelty. Arthropods demonstrate extreme appendage diversity at multiple taxonomic levels, are relatively easy to maintain in laboratory cultures, and genetic tools developed in Drosophila are beginning to be applied across the phylum. A a wide range of techniques are used including, but not limited to: DNA sequencing and phylogeny inference, antibody staining and in-situ hybridization, molecular evolution, RNA-interference, and cell lineage tracing.

Major ongoing projects:

  • Evolution and development of abdominal limbs in insects.
  • Patterns of development in the insect wing in non-holometabolous (directly developing) insects
  • Hox gene expression characterization in Xenylla pseudomaritima (Collembola)
  • Hox gene expression characterization in Ephemeroptera
  • Hox gene expression characterization in Odonata

Ecology and Systematics

Kathryn Perez, Ph.D.

Research interests: Systematics, taxonomy, malacology, biogeography, ecology, biology education research.

This research integrates evolutionary biology and ecology, specifically applying the tools of molecular and morphological systematics and ecology to study taxonomy, ecology, conservation, and helicograph of terrestrial, freshwater, and marine snails. One major research project studies the systematics and taxonomy of the Polygyridae, a family of land snails in the United States and Mexico. A second research area is the study of the origin and colonization of the invasive freshwater snail Bithynia tentaculata. A third ongoing research project examines the distribution and diversity of local land snails using spatial analyses, geographic information systems (GIS), and environmental niche modeling. Finally, we are conducting several research projects on how students learn the nature and process of science and evolutionary concepts.


Ecology and Entomology

Rupesh Kariyat, Ph.D.

Research interests: Ecological effects and molecular mechanisms underlying herbivore-pollinator- plant interactions in native and non-native, natural and agricultural ecosystems.

Using tools derived from chemical ecology to field biology, I plan to understand the signaling mechanisms and ecological effects of species interactions, focusing on herbivores, pollinators and their host plants. These include understanding behavioral modifications of herbivores to counter plant defenses, floral rewards and pollinator behavior, and oviposition behavior and flight muscle development in moths- to name a few. In addition, using electrophysiology and molecular genetics, I also examine the resistance factors in cereal crops (e.g., Sorghum) against sucking insects such as Aphids, and invasive ecology of the weed Solanum eleaegnifolium in Mediterranean region.


Ecology and Medical Entomology

Christopher Vitek, Ph.D.

Research Interests: Biology and ecology of mosquitoes, especially container breeding mosquitoes; arboviral transmission dynamics and factors that influence the probability of infection and transmission.

This laboratory engages in ecological and medical entomology research. It has a range of ongoing projects, including field and laboratory based research. The lab focuses on mosquito biology. Mosquitoes are a useful organism to study due to its aquatic and terrestrial life stages. Research in our lab is not limited to these organisms or questions, however, and past students have studied mosquito repellants and conducted bloodiest studies of insects in the Rio Grande Valley. We collaborate with other laboratories to examine the phylogeny relationship of some unique insects that are found only in Texas and the Rio Grande Valley. Other insect families and orders can be researched as well, and students have been involved in field research examining the use of other Dipterans in biomonitoring.

Laboratory based research includes the examination of environmental influences of insect behavior and biology, including oviposition behavior, hatching behavior, and larval development. The hatch behavior in mosquitoes (specifically container breeding mosquitoes) is a complex behavioral trait, with many factors influencing hatch rate and subsequent larval development. Organisms can utilize both environmental as well as maternal cues to predict future habitat risk, and utilize behavioral plasticity as a mechanism to cope with changing environments. Field work focuses of assessing and monitoring insect populations to identify seasonal and yearly trends in population abundance, emergence, and the potential for disease transmission by disease vectors. In addition, we examine species distribution and how these may influence disease transmission dynamics.



Environmental Science

Frank J. Dirrigl, Ph.D.

Research Interests: Environmental Biology and Land Use Ecology. Rare Species Biology and Conservation. Comparative Vertebrate Osteology and Taphonomy.

Our research interests are interdisciplinary drawing on both the natural and social sciences as they can be applied to evaluate and interpret relationships between people, the environment, and natural resources in the past, present, and future.

1) Currently, the environmental science research/consulting involves biological investigations of the response of indicator species and species guilds to land-use development. We are particularly interested in biomonitoring pre and post construction activities to access the potential impacts from environmental engineering structural designs and practices on wildlife. One long-term project, involves the use of rapid benthic invertebrate sampling protocols and monitoring to assess wildlife benefits resulting from open channelization and culvert systems. We have found that even in localized urban areas that invertebrate and vertebrate species respond positively to open channelization as habitat suitability increases and naturalizes. Based on this information, we develop and evaluate best management practices (BMPs) and their potential to support wildlife.

2) Another research/consulting area involves the field survey for rare species and gathering of natural history information that is useful to conservation biology. One project has involved the development of a conservation ranking scheme for the protection of vernal pools in the Northeast US based on Natural Heritage Methodology of The Nature Conservancy and NatureServe. By identifying the conservation-priority of vernal pools, development plans can be modified to avoid and mitigate potential impacts to wetlands and the natural resources that they support.

3) Finally, we also conduct comparative vertebrate osteology research/consulting with an emphasis on birds. We are interested particularly in how bone biology, such as bone mineral density (BMD), affects the preservation of palaeontological samples. This focus has lead to numerous taphonomic evaluations of archaeozoological assemblages that result in gaining a better understanding of the different factors that affect researchers’ abilities to reconstruct animal use by people in prehistoric and historic contexts.


Food Microbiology

Luis Materon, Ph.D.

Research Interests: Food microbiology, Salmonella, Escherichia coli O157:H7, Listeria, coliforms, fruit and vegetable contamination, lactic acid, aqueous chlorine, disinfectants.

Fruits and vegetables when not handled properly can serve as vehicles for microorganisms that cause product spoilage and human disease. Coliform bacteria, including faecal coliforms, are frequently associated with fresh produce. In our lab, we are currently investigating several combination of disinfectants (lactic acid, Tsunami, and aqueous chlorine), surfactants (Tergitol), exposure times and temperature, in an attempt to obtain a more effective antimicrobial activity on pathogenic bacteria such as Salmonella, Listeria and E. coli O157:H7. We are interested in fruit and vegetable locally grown and in the development of rapid detection kits to test produce imported from Mexico. Another aim is to identify sources of contamination from collection to packing in industrial sheds.


Gene Expression and Nanoparticles

Boris Ermolinsky, Ph.D.

Research Interests: Nanoparticles, bacteria, eukaryotic transfection, gene expression.

Silver ions and silver-based compounds are highly toxic to microorganisms. Silver in the nitrate form is generally used to induce antimicrobial effect, but silver nanoparticles (AgNPs) offer a considerable increase in the surface area available for microbe exposure. Although the antibacterial effect of AgNPs has been widely described, their mechanism of action is yet to be elucidated. The potent antibacterial and broad-spectrum activity against a wide range of morphologically and metabolically different microorganisms seems to correlate with a multifaceted mechanism by which nanoparticles interact with microbes. Several studies have shown that AgNP activity depends on size perhaps because smaller nanoparticles are more effective in penetrating bacterial cells than large ones. This is supported by observations that nanoparticles with smaller diameter and a positive zeta potential cause enhanced cell death. While most investigators are addressing size of AgNP, shape is likely to play significant role in antibacterial activity also. Because this area of investigation is presently neglected the role of AgNP shape in antibacterial activity is being investigated in a collaborative effort. A Rice University group in Houston will synthesize and characterize nanoparticles of different sizes and shapes, and we will evaluate biological activity on a set of bacterial models.


Herpetology. Energetics

Fred Zaidan, Ph.D.

Research Interests: Bioenergetics, Digestive Physiology, Geographic Range Limiting Factors, Herpetology, Physiological Ecology, Reproductive Hormone Cycles, Snake Ecology.

We are interested in understanding how the underlying mechanisms of the environment-physiology interaction serve to shape the distribution and abundance of organisms. In order to address my questions, we adopt an integrative approach that utilizes the tools from physiology, ecology, morphology, behavior, evolution, and statistics. We use a variety of field and laboratory techniques in our research.
How an organism allocates time and energy under varying environmental conditions and how the environment influences hormonal cycles are central themes in our research. The main study organisms are snakes (particularly pit vipers in the genera Agkistrodon [cottonmouths, cantils, copperheads] and Crotalus/Sistrurus [rattlesnakes] and water snakes in the genus Nerodia). We also have interests in the other reptiles, amphibians, and several invertebrate groups (arachnids, cockroaches, and slugs).


We broadly divide my work into two groups (eco-phys and ecology/behavior). Some of the projects that we am currently investigating with the invaluable collaboration of students and colleagues include energetic and hormonal responses to osmoregulation in water snakes, energy allocations and thermal biology in scorpions and cockroaches, digestion and nutrition in snakes, testosterone cycles in montane rattlesnakes in Nuevo Leon, and fossorial snake ecology.


Landscape Ecology

Teresa Feria

Research Interests: landscape ecology, plant populations, remove sensing.

TPWD Number: 495083

PROJECT TITLE  Johnston’s frankenia (Frankenia johnstonii) population status: year one in the post-delisting environment

PROJECT DESCRIPTION AND JUSTIFICATION: The recent post-delisting monitoring (PDM) plan published for Johnston’s frankenia (Frankenia johnstonii) (U.S. Fish and Wildlife Service 2016) outlines the need for monitoring the population status of this species based on 1) remote sensing and 2) on-site assessment within a subset of populations. Remote sensing will be used to predict the potential landscape-level impacts on the habitat of Johnston’s frankenia while on-site assessments are needed in order to evaluate the potential residual impacts that landscape modifications might have on the populations (e.g., population declines).  After a species is delisted, USFWS typically requires 5 years of PDM efforts. However, the Johnston’s frankenia PDM is planned for 9 years in order to provide more time for the monitoring of residual impacts that could impact the habitat of this species and that could be associated with landscape modifications (e.g., road construction). The post-delisting document for this species stated that the on-site monitoring should be developed in a 9 population subset from Zapata, Webb and Starr counties. Two of these populations have been already monitored by Anna Strong. Thus, in this project we will develop the on-site assessment of the remaining 7 population subset from Zapata, Webb and Starr counties, TX in order to: 1. survey known areas of plant occurrence and map population perimeters  2. estimate population size  3. document overall site conditions associated with populations including habitat disturbances.

 We are already developing the surveys and had the opportunity to engage the community on the importance of the Conservation License Plates support for our project.  (Pictures below).

 A link about the Conservation License Plates:  http://www.conservationplate.org/


Mammalian Reproduction Physiology and Breast Cancer

Robert Dearth, Ph.D.

Research Interests: Hormonal regulation of breast cancer development and breast cancer.

The female reproductive system is based on a cascade of complicated events,requiring the aid of several different organs, culminating to maintain reproductive vitality and fertility. Exogenous and endogenous-induced disruptions during critical points in a women’s life (i.e. puberty and pregnancy) can dictate her well-being for the rest of her life (induction/protection from cancer and infertility). The goal (as a neuroendocrinologist) is to aid in the discovery of new/improved ideologies that will advance female reproductive sciences. Specifically, my current and future research will focus on two main areas: 1.) Reproductive factors that affect breast cancer, and 2.) toxicological effects on female reproduction.


Microbial Ecology

Christine Lowe, Ph.D.

Research Interests: Metal-reducing bacteria, metal-oxidizing bacteria, sediment microorganisms, metal remediation, plant-microbe interactions.

There are currently 3 research projects ongoing in my lab:

1) We are currently working on an interdisciplinary study of marine metal accumulating sea grasses (Thalassia sp.) in the Laguna Madre, a large salt water lagoon separating South Padre Island from the Texas coast. Sea grass plants in the Laguna Madre accumulate high levels of manganese and copper metal in their vegetative parts; however, the levels of metal bioaccumulated by the sea grass are several orders of magnitude higher than the surrounding seawater. We hypothesize that microorganisms in the lagoon sediment are converting minerals containing manganese and copper into bioavailable forms that are taken up by the plants through their roots. We are currently conducting an ecological survey of the sediment microorganisms to determine the density, distribution, and identity of manganese and copper-related organisms.

2) We are currently examining the abundance of arsenic bacteria in the Rio Grand River. Arsenic exists primarily in 2 forms in the environment: a less toxic, immobile form known as arsenate (AsV) and a more toxic, cancer-causing, water-soluble form called arsenite (As III). Water from the Rio Grande River is used for agricultural irrigation and there is a concern that arsenic may begin to accumulate on farmlands irrigated with Rio Grande River water. Anaerobic bacteria in the river sediment may potentially convert arsenate into arsenite. We are using arsenate-reducing bacteria isolated from the Rio Grande River to estimate the rate of bacterial arsenic conversion in this and other riparian environments.

3) Many microorganisms can tolerate high levels of toxic metals in the environment because they possess plasmid-mediated resistance mechanisms. We are currently using enrichment cultures to isolate bacteria from the Rio Grande River and the Laguna Madre, which can tolerate high levels of chromium, copper and nickel, and determine whether they possess naturally-occurring plasmids for metal resistance.


Microbial Genetics and Genomics

Erin Schuenzel, Ph.D.

Research Interests: Population structures of pathogens, bacterial genome, evolution, bioinformatics, computational biology, real-time PCR diagnostic assays.

Current research in the lab includes:

1) Population structures of foreign and emergent pathogenic bacteria. Several of the bacteria currently under study include Candidatus Liberibacter ssp., Xylella fastidiosa, Xanthomonas campestris, Acidovorax avenae and Pseudomonas syringae. Multiple strains of the bacteria are analyzed at several genetic loci to understand how the strains are related to each other using bioinformatic techniques.

2) Population structures of plant pathogens. Plant pathogens are not restricted to bacteria and current work is also examining the genetics of invasive insect pathogens including fruit flies from the family Tephritidae and the Asian gypsy moth, Lymantira dispar.

3) Comparative genomics of bacteria. With the large number of bacterial genomes available, the ability to ask questions and test hypotheses on genome evolution is more accessible than ever. Current research is focusing on the role of natural selection in host adaptation, the effects of host immune response on bacterial pathogen evolution, the rate of recombination in genomes, and the effects of inversions on gene expression. While bacteria are the main focus of the lab, we are open to asking the same questions on other organisms such as population structures of eukaryotes and comparative genomics of mammals.


Molecular Endocrinology

John Trant, Ph.D.

Research Interests: to be posted soon


Molecular Neurobiology

Julie Mustard, Ph.D.

Research Interests: Molecular mechanisms of learning and memory, honey bee behavior, the effects of alcohol and caffeine on the nervous system.

What changes in the brain take place to allow us to learn and remember information?The honey bee, Apis mellifera, is an excellent system in which to investigate the mechanisms of learning and memory due to its outstanding ability to learn and its well characterized neurobiology. Current research focuses on the roles of biogenic amines in learning and memory. The biogenic amines are small intercellular signaling molecules that act as neurotransmitters and neuromodulators. They affect cells via binding to G protein coupled receptors that are expressed on the surface of responsive cells. The biogenic amines and their receptors are highly conserved across species; therefore, studying them in bees can provide insight into how they function in humans. Areas of research include: 1) Understanding the roles that the biogenic amines dopamine, octopamine and tyramine play in learning and memory and other behaviors; 2) Molecular and pharmacological characterization of the biogenic amine receptors; 3) Investigating how drugs of addiction, such as caffeine and alcohol, affect the reward pathways normally controlled by octopamine and dopamine.


Neurobiology

Zen Faulkes, Ph.D.

Research Interests: neuroethology, evolution of nervous systems, sensory-motor integration

I study brains, behavior, and evolution, mainly in crustaceans. Current projects include the biology of the parthenogenetic marbled crayfish; vision in digging sand crabs; responses to noxious high temperatures; escape responses, and; the trade in crayfish as pets.


Nitrogen Fixation

Luis Materon, Ph.D.

Research Interests: Nitrogen fixation, Rhizobium, legumes, soil fertility, strain selection, competition, nodulation.

Symbiotic root nodulating bacteria, commonly known as rhizobia, have great environmental and agricultural importance since their symbiosis with legumes supplies the plant partner with biologically fixed nitrogen. Therefore effectively leguminous plants may show increased yields without the application of costly industrially produced nitrogen fertilizer. The primary aim of current research is to increase the application of biological nitrogen fixation in the Lower Rio Grande Valley agriculture in southern Texas. To achieve this aim, two main research areas have been identified: Strain collection from all agricultural areas, strain competitiveness with indigenous rhizobia and their long term persistence in soil. A taxonomic characterization of bacterial symbionts from agronomically and ecologically important legumes is necessary to determine the extent of the diversity of rhizobial populations. Such data, together with studies on strain competition for nodulation, can subsequently increase biomass production and soil fertility.


Ornithology

Timothy Brush, Ph.D.

Research Interests: Avian ecology, green parakeet, long-billed curlew, changing birdlife, breeding biology, shorebirds, bird conservation.

We are interested in habitat use, ecology, and conservation of the birds of the Lower Rio Grande Valley. In previous studies, we have focused on shorebirds along the Lower Laguna Madre, including the declining Piping and Snowy plovers and other species of conservation concern. We have also looked at the current status of various bird species in the Valley, including Red-billed Pigeon, Elf Owl, Northern Beardless-Tyrannulet, Black Phoebe, Rose-throated Becard, Clay-colored Robin, Tropical Parula, Altamira Oriole, Audubon's Oriole, and Olive Sparrow, as well as looking at the effects of Bronzed Cowbirds, habitat fragmentation, and lack of flooding on breeding bird communities of riparian forest and scrubland.

A major project has been a historical study of the breeding birdlife and habitats of the Lower Rio Grande Valley, to be published as a book by Texas A&M University Press in Fall 2005. We have collaborated with researchers from Texas A&M University in a study of bird species of conservation concern in southern Texas and northeastern Mexico. We continue to be interested in the changing birdlife of the Valley and have begun baseline studies of two poorly known species of conservation concern, the Green Parakeet and the Long-billed Curlew to better determine their current statuses in the region. We will also continue to pursue my interest in the changing birdlife of the Valley and adjacent southern Texas and northeastern Mexico.


Plant Biochemistry

Michael Persans, Ph.D.

Research Interests: Toxic chemicals, herbicide metabolism, metal toxicity, phytoremediation.

The main topics of this research are: the isolation and characterization of genes involved in heavy metal tolerance in plants, the metabolism of herbicides by plants and the use of remote sensing to monitor environmental pollution caused by heavy metals using plants as a model indicator organism. These projects also relate to human health in that they are involved in the sensing and fate of toxic chemicals in the environment

The herbicide metabolism project involves the study of Cytochrome P450 enzymes in plants and how they detoxify herbicides. By studying these enzymes in plants we hope to learn more about the mechanisms of toxin metabolism and apply these results to further understand the mechanisms that plants may use to detoxify drugs.

The tolerance of plants to heavy metal toxicity is another project in the lab. By understanding the mechanisms by which heavy metals are tolerated, a possible scheme could be devised for the phytoremediation of heavy metals. In addition, plants genetically engineered to hyperaccumulate large amounts of heavy metals could be used for phytoremediation purposes to clean up toxic sites which may be health threats.

The remote sensing project seeks to study the effects that stress such as pathogen attack and heavy metal poisoning has on the spectral properties of plants. By observing the effects that stress has on plants early, plants may be used as early indicators of metal toxicity in the environment and/or indicators of pathogen attack.


Plant Physiological Ecology

Bradley Christoffersen, Ph.D.

Research Interests: plant ecophysiology and water relations, ecohydrology, forest ecosystem ecology, modeling of plant hydraulics

I am interested in how plants use diverse ecological strategies to maximize growth, survival, and reproduction under conditions of water scarcity, and the impacts of such ‘functional diversity’ on the resilience and vulnerability of ecosystems to environmental change. Historically I have pursued these questions in tropical forests, but will be expanding my focus into native and disturbed ecosystems of the Rio Grande Valley. I will use diverse approaches including minirhizotrons to study fine root growth and turnover in response to varying hydrological regimes; micrometeorological techniques (eddy covariance) to study the net exchange of carbon, water, and energy between the land and atmosphere, lab-based investigations into the impact of tree allometry, architecture, and phenology on the diversity in stem and leaf hydraulic traits of native thornscrub species, and model-data fusion techniques for high-frequency environmental data on plant-water relations, such as continuous sap flow (stem water use) and water potential measurements from in situ plant sensors.


Plant Taxonomy

Andrew McDonald, Ph.D.

Research Interests: Plant Systematics, Tropical Biogeography, Conservation of Biodiversity, Ethnobotany and Economic Botany.

Plant Systematics

The Plant Systematics program at UTRGV investigates a variety of plant groups in distant reaches of the world. One prominent component of my research program investigates species diversity and adaptive radiation in New World morning glories (Convolvulaceae). These activities complement floristic research on plant communities that inhabit limestone substrates in northern Mexico, Laos, and Cambodia, with an eventual aim to elucidate the biogeographic relationships between disjunct plant groups of tropical North American and Southeast Asia. The Plant Systematics laboratory and Herbarium (PAUH) also supports students that are interested in the natural history of the Rio Grande Valley flora, with emphasis on rare and endangered species.

Ethnobotany

Following studies made in the field of archaeo-ethnobotany, we continue to explore lotus imagery in mythic and artistic traditions of the New and Old World. These investigations now include the study agricultural practices in prehistoric Indo-Aryan societies, with a focus on the domestication and dissemination of barley (Hordeum) and the eastern lotus (Nelumbo


Population/Community Ecology

Frank W. Judd, Ph.D.

Research Interests: Physiological, population and community ecology, revegetation, native habitats.

The research deals with the span all three principal subdivisions of ecology, i.e. physiological, population and community ecology. Recent research is devoted primarily to community ecology. We jointly publish on the community ecology of freshwater, brackish and salt marshes of the Rio Grande Delta, the flowering, fruiting, and branch elongation phenology of 4 Acacia species and Texas ebony, the recovery of vegetation at Padre Island National Seashore following a wildfire, and we have evaluated Texas Parks and Wildlife Department and U.S. Fish and Wildlife Service efforts at hastening succession in their revegetation programs. We also studied the efficacy of U.S. Fish and Wildlife Service revegetation efforts in promoting rodent community diversity. Work currently in progress is aimed at quantifying dune migration at South Padre Island in relation to vegetation cover. We hope to develop a predictive model for elevation change based on cover derived from remotely acquired imagery. A book on Native Habitats of the Lower Rio Grande Valley is also in progress.


Toxicology

Mohammed Farooqui, Ph.D.

Research Interests: Toxicology, aliphatic nitriles, pesticides, pharmacokinetics, GSH, cyanide.

Our current research involves effect of common beverages such as coffee products and alcohol on the toxicity and metabolism of aliphatic nitriles. In general my interest focuses on various toxic aspects of environmental and industrial chemicals on human systems. In more specific terms, we am interested in molecular interactions and metabolism of these chemicals and trying to understand their mechanisms of actions through the studies on various organ systems in laboratory animals. These studies are useful in exploring human health risks.

For about two decades we have been involved in such studies on chemicals including pesticides (DDT and its analogs) in insects and industrial chemicals (acrylonitrile, propionitrile, dimethyl aminopropionitrile, formaldehyde, methacrylonitrile and allynitrile) in laboratory animals including rats and mice. Actual investigations involved the studies on the in vivo and in vitro metabolism, pharmacokinetics in blood and other organ systems, molecular interactions and covalent binding with biomolecules including DNA, RNA, proteins and lipids.

In our studies we have found that the toxicity and other actions of aliphatic nitriles are not entirely due to their ability to generate cyanide ions in biological system as previously believed, but also due to either entire molecule or metabolites other than cyanide. For example many of the nitriles are capable of forming epoxides in vivo and become more potent alkylating agents. Also, these chemicals exploit the glutathione (GSH) pathway. These chemicals form GSH conjugates and result in depletion of GSH which in itself is detrimental to the survival of normal cells.


Viral Pathogenesis

John Thomas, Ph.D.

Research Interests: to be posted soon.