PERT Faculty Interests
(back to Faculty list | PERT home page)
• Jennifer K. Barton - Biomedical Engineering and Electrical and Computer Engineering
The focus of Dr. Barton's current research is on Optical Coherence Tomography. OCT is a non-destructive imaging technique which uses infrared light to visualize subsurface structure in biological tissues. Depths of a few millimeters can be imaged with about 20 micrometer ( F m) resolution. OCT is analogous to ultrasound imaging, but the magnitude of reflected light is measured instead of reflected sound waves. OCT achieves relatively high resolution and large depth of imaging by combining characteristics of confocal microscopy and white light interferometry. OCT uses a special light source with a short coherence length in a fiber Michelson interferometer arrangement Only light which travels the same distance in both the sample and the reference arms of the interferometer will interfere and be detected. Images of subsurface tissue structure can be built up pixel by pixel, by moving the reference arm mirror and by scanning the sample arm across the tissue. She is specifically working on the technologies of miniature endoscope design and image processing. She is interested in applications of this technology to cancer (skin, colon, and ovarian) and vascular implants.
• Judith Becerra - Department of Entomology
Dr. Becerra is an evolutionary ecologist interested in insect-plant interactions. Her research combines ecological and chemical information with molecular phylogenetics and character reconstruction to identify macroevolutionary patterns of host shifts, co-adaptive forces shaping coevolution and evolutionary strategies of plant chemical defenses. She is also interested in chemical interactions between insects and plants.
• Giovanni Bosco - Molecular and Cellular Biology, and Arizona Cancer Center
Dr. Bosco is interested in understanding how cell cycle events (such as DNA replication, chromosome segregation and cell growth and cytokinesis) are controlled and modified by development. Despite the fundamental role development plays in modifying cell cycle control, there is little known about the factors that coordinate cell cycle events with the spatial and temporal constraints of development. In many human cancers, these constraints have been lost and cells undergo unchecked proliferation. He would like to understand how tissue specific cell cycles are regulated, and thus shed light on how tissue specific tumors arise in humans. Current studies are focused on the control of DNA replication in the Drosophila ovary. His lab has discovered that the Drosophila homolog of the human retinoblastoma tumor suppressor (pRB) is involved in controlling both endo cycles and gene amplification. However, we do not know what developmental factors regulate the fly pRB pathway and instruct cells to shut off DNA replication. They are using a combination of genetic, biochemical, and cell biological techniques to answer these questions. They are also developing genomic and proteomic technologies to address this fundamental problem in biology. In the future, they plan to use Drosophila as a tool for large scale drug screening projects in order to identify novel compounds that can potentially be used for cancer therapy.
• Judith Bronstein - Department of Ecology & Evolutionary Biology
Dr. Bronstein's lab focuses on the study of interspecific interactions, particularly on the poorly-understood, mutually beneficial ones (mutualisms). Specific conceptual areas of interest include: (i) evolutionary conflicts of interest between mutualists and their consequences for the maintenance of beneficial outcomes in these interactions; and (ii) context-dependent outcomes in both mutualisms and antagonisms. Her primary research systems are the mutualisms between tropical figs and fig wasps, and between yuccas and yucca moths in desert grasslands; in both cases, the insect is simultaneously a host-specific pollinator and a seed predator. Using a combination of field observations and experiments, she is examining how population processes, abiotic conditions, and the community context determine net effects of the interactions for the fitness of each participant.
• Judith Brown - Department of Plant Sciences
Dr. Brown's research interests focus on the virology of whitefly-transmitted plant viruses, whitefly-geminivirus interactions which facilitate virus transmission, and whitefly-host interactions that impact on disease spread in monoculture/ weed agroecosystems. Projects include: 1) biological and molecular investigations of previously uncharacterized viruses for the purpose of understanding disease epidemiology, and to identify virus genes for the use in developing engineered resistance strategies, 2) the correlation of virus-vector transmission characteristics with in situ localization of geminiviruses in the whitefly vector, and 3) molecular level investigations of biologically distinct B. tabaci biotypes or populations. The long-range goal is to develop strategies by which plants can be engineered for resistance to virus infection and/or to interfere with virus-vector interactions, which are necessary for whitefly-mediated transmission.
• Richard C. Brusca - Center for Sonoran Desert Studies, Arizona Sonora Desert Museum
Dr. Brusca is an evolutionary biologist and invertebrate zoologist with interests in invertebrate systematics, phylogenetics, biogeography, and biodiversity pattern analysis. His principal appointment is Director of Conservation and Science at the Arizona-Sonora Desert Museum where he works with several other specialists on Sonoran Desert natural history. He would like to work with a postdoc interested in developing a research project in the area of insect biodiversity that would dovetail with existing or planned field programs through the Desert Museum. Museum researchers are currently engaged in several projects in northwestern Mexico/southern Arizona that could benefit from an additional entomological component. Some current programs are: (1) Insect biodiversity and land use change in Sonora: biodiversity across natural and anthropogenic landscapes in northwestern Mexico. (2) Tropical corridors linking Mexico and the United States: biotic linkages and trans-border routes in a basin-and-range landscape. Other project ideas integrating insect biodiversity into the research and teaching programs of the ASDM will also be considered, including projects focusing on the two N.W. Mexico Biosphere Reserves (i.e. the El Pinacate/Gran Desierto B.R. and the Upper Gulf of California/Colorado Delta B.R.). The postdoctoral candidate would work at the ASDM, under the supervision of Dr. R.C. Brusca, and be expected to cooperate with existing research and education staff.
• Yves Carriere - Department of Entomology
The last fifty years have shown that insect pests have strong potential to evolve resistance to synthetic pesticides and resistant plants produced by traditional methods of selection. One important goal of Dr. Carriere's research is to develop deployment strategies for transgenic plants that maximize durability of resistance. Model systems include a sap-feeding generalist insect, the sweetpotato whitefly, and a specialist lepidoptera, the Pink bollworm. To determine how to build and use transgenic plants for whitefly control, the interaction between different introduced plant and insect genes and whitefly behavior, population dynamics, susceptibility to natural enemies, and rate of evolution of resistance is being investigated.
• Vicki Chandler - Department of Plant Sciences
Dr. Chandler's research program investigates the regulation of gene expression. The anthocyanin biosynthetic pathway in maize is the focus of their work, as it provides an exceptionally tractable system for genetic, biochemical and molecular approaches. A major emphasis in their research is to investigate how the regulatory genes of this pathway are controlled. These regulatory genes, which encode transcription factors that activate the anthocyanin biosynthetic genes, have multiple alleles that produce distinct developmental and tissue-specific patterns of anthocyanin pigments. In addition, they have identified negatively acting modifier genes that reduce the expression of the biosynthetic and regulatory genes. Identifying the cis-acting sequences regulating differential expression, and factors that interact with these sequences should provide important information on mechanisms of gene regulation, applicable to numerous plant systems. In addition, the availability of regulatory sequences that can control expression in distinct tissues and developmental stages will greatly enhance the potential of genetic engineering. They are also using this system to investigate mechanisms of gene silencing, which has a fundamental role in development of all organisms and has recently become a major problem with genetic engineering approaches to crop improvement. They use both forward and reverse genetic approaches to study paramutation, the regulation of transposable elements and transgene silencing. Paramutation is a mitotically and meiotically heritable change in gene expression that is induced by allele interactions. They have demonstrated that the heritable change is accompanied by a ten- to twenty-fold reduction in transcription. Recently they have used a combination of classical genetics, genomics, and molecular methods to identify and characterize the minimal sequences required for paramutation, which map within 99-106 kbp upstream of the transcription initiation site. They have also identified multiple mutations in other genes required for the establishment and maintenance of paramutation. They have shown that these mutants also activate previously silent transposable elements and transgenes, indicating that the wild type proteins are required for multiple gene-silencing processes. Experiments are in progress to clone the genes represented by these mutations and determine their role in gene silencing. As heritable changes in chromatin structure are clearly involved in the establishment and maintenance of distinct transcription states they are also pursuing a functional genomics approach to understand chromatin-level control of gene expression in both maize and Arabidopsis.
• Michael Cusanovich - Department of Biochemistry & Molecular Biophysics
My laboratory has as primary interests two broad areas: biological recognition, that is, the mechanisms used by proteins for recognition and specificity in physiologically relevant reactions, and protein dynamics, that is, large, relatively fast intramolecular motions that are important in protein function. We use two systems to study biological recognition and protein dynamics. First, biological energy transduction is required for life processes. Our laboratory is actively working on a variety of problems focusing on the mechanism of biological electron transfer. Redox proteins have to recognize their physiologically relevant electron donors and acceptors with high specificity, transfer electrons efficiently, and cycle between redox states. For example, c-type cychromes shuttle electrons between the cytochrome bc1 complex and cytochrome oxidase in higher animals. We are particularly interested in the physical and chemical interactions mediating protein-protein interactions which control specificity, protein stability and protein dynamics in electron transfer. Second, we have a major effort underway to fully characterize and understand photoactive yellow protein (PYP) from bacteria. PYP is the structural prototype for the diverse super family of PAS domain containing proteins which are found in all kingdoms of life. The PAS domain containing super family serve as sensor proteins, with a diverse range of functions sensing stimuli ranging from light, oxygen, redox potential, to an array of small molecules. The common motif is interacting with a stimuli in the sensor domain, followed by a structural change resulting in a signaling state which then interacts with a response regulator to initiate a system response. Our approach to these problems uses a variety of kinetic techniques and structural approaches to relate the time course of events to structural and chemical features of these macromolecules. These techniques include stopped-flow, laser flash photolysis and perturbation methods as well as computer modeling of the kinetic mechanism and protein structure.
• Goggy Davidowitz - Department of Ecology & Evolutionary Biology
My broad area of interest is in ecological development: how organisms adjust developmental pathways in response to short-term environmental variation. Specifically, I am focusing on the physiological mechanisms by which insects translate variation in diet quality and temperature, two environmental factors with strong effects on life histories, into phenotypic variation in body size and development time, two traits highly correlated with fitness. In my work I emphasize the regulation of these traits at the level of the whole organism. The complexity of the traits and the mechanisms that regulate them have led me to develop an integrative research program. Currently, I am employing techniques from quantitative genetics, physiology, endocrinology, ecology, evolutionary biology, behavior, and elemental stoichiometry, combining lab, greenhouse and field work.
• Anna Dornhaus - Department of Ecology & Evolutionary Biology
Organization in groups, how collective behaviors emerge from the actions and interactions of individuals, is the main interest of Dr. Dornhaus. As model systems she studies social insect colonies (bumble bees, honey bees and ants) in the laboratory and in the field, as well as using mathematical and individual-based modeling approaches. She investigates mechanisms of coordination in foraging, collective decision-making, task allocation and division of labor. Her recent work has included the role of communication in the allocation of foragers to food sources; the evolution of different recruitment systems in different species of bees, and how ecology shapes these recruitment systems; house hunting strategies in ants; speed-accuracy trade offs in decision-making; and whether different group sizes necessitate different organizational strategies.
• Andrew J. Fuglevand - Department of Physiology
The broad goal of the work carried out in my lab is to understand how the mammalian nervous system controls the action of skeletal muscles to produce coordinated movements. Our experiments address a range of topics from those related to how individual neurons integrate synaptic information to those associated with the development of new methods to restore movement and sensation in paralyzed individuals. This work has been supported continuously by the National Institutes of Health since 1995. We are currently engaged in the following basic and applied research projects: investigation of the neural and muscular mechanisms that underlie the control of finger movements; characterization of the fundamental properties by which motor neurons integrate synaptic information; studies of the rules governing communication between somatosensory afferents and spinal motor neurons; identification of the neural and muscular factors underlying fatigue; characterization of the patterns of facial muscle activity associated with facial expressions; development of new methods to restore movement in paralyzed limbs using functional electrical stimulation; development of an electrotactile-stimulation system to restore sensation in individuals with spinal cord injuries.
• David Galbraith - Department of Plant Sciences
Dr. Galbraith's program focuses on four main areas: Biological Instrumentation, Developmental Plant Gene Expression, Plant Functional Genomics, and Plant-Insect Interactions. His work aims to characterize those plant genes that are responsive to abiotic stress, particularly osmotic and salt stress. His laboratory provides scientific resources to the research community, in the form of EST sequences, insertional mutants, and genomic information.
• Wulfila Gronenberg - Arizona Research Laboratories, Division of Neurobiology
Dr. Gronenberg's interests include ecological and evolutionary aspects of neuroethology as well as movement control, muscle function and biomechanics. His interests extended from the periphery to the central brain regions where more complex behavior is generated and controlled.
• Charles M. Higgins - Arizona Research Laboratories, Division of Neurobiology, and Electrical & Computer Engineering
The laboratory of Professor Charles M. Higgins employs a combination of engineering and biological methods to study the neuronal mechanisms of insect visual navigation. This research includes biologically-detailed simulation experiments, VLSI "vision chip" development, and applications to autonomous robotics.
• John G. Hildebrand - Arizona Research Laboratories, Division of Neurobiology
The research in Dr. Hildebrand's laboratory combines molecular, morphological, neurophysiological, and behavioral methods in a multidisciplinary approach to problems of the function and development of the insect nervous system. Areas of principal interest are: functional organization and physiology of the central olfactory pathways; postembryonic development of the central nervous system; chemosensory control of behavior; chemical ecology of moth-hostplant interactions; synaptic mechanisms; molecular and biophysical studies of the function of olfactory receptor cells; and neural control of pheromone production.
• Martha Hunter - Department of Entomology
Dr. Hunter's research area is biological control and the ecology and evolutionary biology of parasitoids and predators. One aspect of my research involves trying to understand how interspecific interactions influence biological control. The lab is currently studying competition and hyperparasitism in two whitefly parasitoids in order to determine whether these interactions may lead to reduced pest suppression. The parasitoids that are of special interest are autoparasitoids; females develop as primary parasitoids of whiteflies, while males develop as hyperparasitoids, developing either on females of their own species or on other primary parasitoids. The sex-specific host relationships of these animals force one to adopt a different perspective on such topics as sex allocation, host selection behavior and parasitoid-host population dynamics. Dr. Hunter is also interested in the effects of selfish genetic elements such as parthenogenesis-inducing bacteria on the behavior and life history of these parasitoids.
• Shanker Karunanithi - Arizona Research Laboratories, Division of Neurobiology
A synapse is a specialized connection facilitating information transfer from a neuron to a target cell by releasing neurotransmitters from synaptic vesicles. Learning and memory formation, stress adaptation, drug addiction and withdrawal, depression, and fear conditioning are examples of behavioral changes reinforced in part by altering the strength of the transmitted signal at individual synapses (synaptic strength). For example, learning and memory formation are correlated with increases in synaptic strength. Intriguingly individual synapses differ in their signaling strengths, and the extent to which their strengths can be modified. Reconciling the diversity in strengths amongst different synapses and their capacity for functional alteration, with changes in behavior remains one of the greatest of challenges. The broad research interests of the laboratory are to elucidate the determinants of synaptic strength under normal and stressful conditions. In particular, to determine the factors generating differences in strengths amongst synapse types, and how synapses functionally adapt to acquire heat-resistance. Drosophila, a model organism whose genome is now sequenced, readily lends itself to genetic, ultrastructural and physiological analysis. Availability of many mutants, and provisions for advanced genetic manipulations are unmatched in any other organism. The readily accessible larval neuromuscular junction preparation which functionally resembles mammalian excitatory glutamatergic synapses will be utilized in our work. The following techniques will be utilized in the laboratory: focal macropatch recording from individual synaptic boutons, intracellular recording, voltage clamping, calcium imaging, UV flash photolysis of caged compounds, serial reconstruction of synapses using electron microscopy, confocal microscopy, immunohistochemistry, DNA microarrays, gel electrophoresis, generation of transgenic Drosophila, RNA interference (RNAi) to silence gene function.
• Carlos A. Machado - Department of Ecology & Evolutionary Biology
Dr. Machado is an evolutionary geneticist interested in a range of topics that include population genetics, phylogenetics, plant-insect coevolution, and the genetic basis of speciation in insects. His main research systems are Drosophila and the fig/fig wasp mutualism. He currently studies the process of species divergence and the genetics of speciation in Drosophila using population genetic data and cDNA microarrays. He also takes advantage of a solid background on the ecology and natural history of figs and fig wasps to ask relevant molecular evolution and population genetics questions. Current interests in that system include studying the genetic consequences of evolution in subdivided populations, the extent of coevolution in Neotropical figs and their pollinators, the geographical context of speciation and cospeciation in the mutualism, and the potential for genetic introgression across different fig species due to pollinator host switches.
• David Maddison - Department of Entomology
Dr. Maddison's research focuses on the evolution of beetles, and phylogenetic biology in general. He has concentrated on the evolution of adult and larval structure, and chromosomes, of ground beetles (Carabidae). The lab is are now studying molecular phylogeny of the major lineages of adephagan beetles. His work in systematic theory centers on developing phylogenetic methods by which we can learn about character evolution. One expression of this work is the computer program MacClade. Dr. Maddison is also the editor and coordinator of the Tree of Life, a distributed Internet project containing information about phylogeny and diversity of all organisms.
• Bill Montfort - Department of Chemistry and Department of Biochemistry
Dr. Montfort studies macromolecular structure and function at atomic resolution using X-ray crystallography. Most of the problems we study address fundamental aspects of protein function using medically relevant examples. Examples are (1) ligand-induced conformational change using the enzyme thymidylate synthase (TS) a potential anti-cancer drug. (2) A second anticancer drug target in the laboratory, the protein thioredoxin(Trx), which exists not only in the cytosol, where it serves as a reductant, but also outside the cell where it stimulates certain growth factors to function more efficiently. (3 A nitric oxide binding protein (NP1) from the salivary gland of the blood- sucking insect Rhodnius prolixus.
• Nancy Moran - Department of Ecology & Evolutionary Biology
Dr. Moran's long-term interests are in the evolution of biological complexity, such as that apparent in complex life histories, in intimate interactions among species, and in species-diversity of clades and communities. Her focus is on symbiosis, particularly that between multicellular hosts and microbes. Symbioses are central in the evolution of complexity; have evolved many times and are critical to the lifestyles of many animals and plants and also to whole ecosystems, in which symbiotic organisms are key players. The primary reason that symbiosis research is suddenly active, after decades at the margins of mainstream biology, is that DNA technology and genomics give us enormous new ability to discover symbiont diversity, and more significantly, to reveal how microbial metabolic capabilities contribute to the functioning of hosts and biological communities.
• Lisa Nagy - Department of Molecular & Cellular Biology
Dr. Nagy is interested in exploring the genetic basis of morphological diversity. To do this, she asks how developmental regulatory networks known to pattern a particular aspect of morphology in one organism are modified in other related organisms. At the moment, her work focuses on the evolution of arthropod body plans. Arthropods show a large degree of variation in segmental and limb patterning. Segments, or groups of segments, have repeatedly become specialized for feeding, walking or swimming. Many of the key genes and genetic pathways that regulate segmentation and limb formation have been worked out through molecular genetic analyses in Drosophila. For example, these genes include the HOX genes or the early segmentation genes linke hunchback, wingless, and engrailed. Dr. Nagy is examining whether morphological evolution involves regulatory changes in otherwise conserved gene networks. Other areas of interest include the molecular evolution of the HOX clusters, the developmental mechanisms underlying phenotypic plasticity and the evolution of altered life history strategies.
• Lynne Oland - Arizona Research Laboratories, Division of Neurobiology
The last decade of research in neurobiology has provoked what to some has been a startling revision in understanding of the role of glial cells in the developing nervous system. No longer just a matrix for the neurons, glia are recognized now to provide signals for neuronal pathfinding, to serve as a physical substrate for neuronal migration, to release needed trophic factors, and to delineate functional regions of neuropil. Dr. Oland's research, carried out in collaboration with Leslie Tolbert, has focussed primarily on exploring development of the antennal lobe of the moth, a system in which glial cells have a prominent role in the process by which the neuropil is partitioned into glomerular compartments. These glomeruli are complex synaptic regions characteristic of first-order olfactory neuropils in vertebrates and invertebrates alike. Interactions between olfactory receptor neurons and glial cells are essential for the construction of stable glomeruli and for the development of the characteristic shapes of antennal-lobe neurons.
• Dan Papaj - Department of Ecology & Evolutionary Biology
Dr. Papaj has a long-standing interest in the dynamics of behavior. Using insects which exploit plants or other insects as hosts (fruit flies, parasitoids, and butterflies), the lab focuses on the mechanisms and function of oviposition behavior and physiology. Themes of mechanism include projects on learning in swallowtail butterflies and effect of egg load on parasitoid host acceptance) on egg-laying behavior in fruit flies. Analyses of function include detailed assessment of fitness consequences of superparasitism. The lab has two physiology-oriented projects on fruit flies, one which examines how host stimuli influence oogenesis and one which uses confocal, electron and standard microscopy to image sperm transfer and storage, and distinguish between sperm competition and post-copulatory 'cryptic' female choice.
• Linda Restifo - Arizona Research Laboratories, Division of Neurobiology
Dr. Restifo's overarching interest is in the genetics of brain development, ranging from the control of large-scale morphogenetic movements to the remodeling of individual neurons. She uses the fruit fly model system, Drosophila melanogaster, in part because of its phylogenetic similarities to mammals. In particular, she is using fruit flies to understand human developmental brain disorders, such as mental retardation and autism, and as a drug-discovery tool. Her methods include genetic manipulations, primary neuron cell culture, immunostaining and confocal microscopy, expression profiling (with Affymetrix microarrays), bioinformatics, and software development for neuron-image analysis.
• Michael Riehle - Department of Entomology
Dr. Riehle's lab is attempting to better understand the mosquito’s physiology and use this knowledge to reduce the mosquito’s ability to transmit disease. The mosquito represents an ideal model organism for examining the role of insulin signaling on reproduction and lifespan because reproduction only occurs after the females have consumed a discrete bloodmeal. This gives researchers precise control over the timing and number of reproductive cycles an individual mosquito has during its life. The insulin signaling cascade is one of the key regulators of egg production in mosquitoes and most likely other invertebrates. Another primary focus of the lab is to determine the genetics of aging in mosquitoes. One of the goals of the lab is to genetically engineer mosquitoes with a shortened lifespan, but without a large decrease in fitness. To accomplish this they are inserting constitutively active activators and inhibitors of the insulin signaling cascade into mosquitoes. Expression of these signaling components will be regulated through a tetracycline inducible system, allowing them to increase or decrease insulin signaling as needed. The hope is that by increasing insulin signaling in the mosquito we can reduce the mosquito’s lifespan while increasing its fecundity, resulting in a mosquito with a reduced vectorial capacity that can still compete effectively with wild mosquito populations.
• Robert Smith - Department of Entomology
Dr. Smith's research interests include the reproductive biology of insects in general and parental care and sperm competition in particular. He is currently working on the reproductive biology of aquatic Heteroptera and the control of reproductivity and caste determination in primitive termites. Dr. Smith is also interested in Southwestern mountain island stream ecology and the conservation of aquatic habitats in southern Arizona. Finally, he is involved in applied research on the biology and management of Arizona's economically important termites.
• S. Patricia Stock - Department of Entomology
Dr. Stock's research interest is biodiversity of insect-parasitic and pathogenic nematodes and their role in ecosystem function. She is actively engaged in biotic survey and inventory projects in different geographic regions of the world, which allow her to make significant contributions toward the discovery of new species, the understanding of the ecology and behavior of insect-parasitic nematodes and their consideration in biological control and integrated pest management programs. Additionally, she is interested in studying the ecology and genetics of nematode populations from agricultural and natural ecosystems, particularly the study of host-parasite relationships and interactions (including plant and insect-parasitic nematodes), such as phoresis, facultative, obligate parasitism, and pathogenesis. A new research area in Dr. Stock's program focuses on the study of Steinernema nematodes and their bacterial symbionts (Xenorahbdus spp.) as models for understanding mutualistic interactions between animals and microbes. Current research relates to the study of structural and developmental features of the bacterial receptacle in the nematode hosts to better understand the colonization process. Her group is also interested in recognizing the chemical signals and physical interactions that occur between the nematode and their symbionts and how these interactions might affect each organism. Furthermore, they also investigate evolutionary histories of both nematode and bacterial symbionts considering a multigene repertoire and study co-evolutionary histories and diversification of these two partners.
• Nicholas Strausfeld - Arizona Research Laboratories, Division of Neurobiology
Dr. Strausfeld's research focuses on understanding neuronal arrangements and interactions that underlie sensorimotor control systems and pathways that mediate learning and memory of spatial relationships. Three main research projects in his laboratory are (1) the elucidation of the cellular and functional organization of the insect visual system; (2) the functional and structural analysis of brain regions involved in learning and memory; (3) brain evolution in arthropods.
• Matthew Sullivan - Department of Ecology & Evolutionary Biology
The Sullivan Lab (a.k.a. The Tucson Marine Phage lab) investigates the co-evolution of microbe and virus (phage) in ‘wild’ populations, as well as the impact of marine phages on microbe-mediated global biogeochemistry. Genomics and model-systems-based experimentation revealed that cyanobacterial phages are numerically abundant and often contain ‘host’ photosynthesis genes. Remarkably, these genes are expressed during infection and act as a diversity generator for their numerically dominant globally distributed photosynthetic hosts. As a complement to this photosynthesis-based phage-host system, we are developing a non-photosynthetic phage-host system using another ubiquitously present surface water marine microbial lineage whose members have a suite of biogeochemically important metabolic features, Roseobacter. Through the use of (meta)genomics, they query 'wild' viral populations to identify important hypotheses that can be evaluated using model-system approaches with appropriate cyanobacterial and/or roseobacterial phage isolates. In addition, they are developing single-cell assays that combine cutting-edge advances in flow cytometry, fluorescence in situ hybridization and genomics to investigate 4 questions that are critical for modeling and predicting the impacts of phage-host interactions in the wild. These questions include gaining an understanding of the in situ host range of phage isolates, the metabolic capacity of uncultured phage-host systems, the impacts of host growth status on phage production, and the fraction of microbial cells that are infected in wild populations.
• Bruce Tabashnik - Department of Entomology
The Tabashnik laboratory studies the evolution and management of insect resistance to biological and synthetic insecticides delivered by conventional means or by transgenic plants. Current work focuses on evolution of resistance to toxins from the bacterium Bacillus thuringiensis (Bt), which are the most widely used biological pesticides. Recent commercialization of transgenic corn, cotton, and potatoes that express Bt toxins has increased the chances that pests will evolve resistance to these environmentally benign insecticides. Thus, knowledge about resistance to these toxins will have immediate applications. During 1998, Bt cotton accounted for more than half of Arizona's 300,000 acres of cotton, which provides exceptional opportunities for field and laboratory research. Specific projects now underway include analyses of pink bollworm resistance to Bt cotton and analyses of the genetic and biochemical basis of resistance to Bt in diamondback moth.
• Leslie Tolbert - Arizona Research Laboratories, Division of Neurobiology
Intercellular interactions are essential for the development of the nervous system. The laboratory is interested in mechanisms underlying the strategic role played by sensory axons in guiding the development of their target areas in the brain. Using the insect olfactory system as a model system, the developmental interactions that influence cell shape and synaptic connections are being explored. Research focuses on the cellular events by which olfactory axons induce the formation of structures called "glomeruli", which appear in virtually all olfactory systems, from invertebrate to human. A major finding is that glial cells are essential for the formation of glomeruli. Using light, electron, and confocal laser-scanning microscopy, intracellular dye-injection, hybridoma techniques and immunocytochemistry, autoradiography, and biochemical assays, the laboratory is exploring the nature of the signal from olfactory axons to glial cells, whether the response of glial cells involves the expression of cell-surface and/or extracellular-matrix-bound molecules, and how such molecules affect subsequent neuronal differentiation. Recent results indicate that an array of glycoconjugates, including one that resembles a vertebrate adhesion molecule, stud the surfaces of glial cells and of neurons; Dr. Tolbert's lab is currently are testing whether these molecules are involved in glial-neuronal interactions.
• Theodore P. Trouard - Biomedical Engineering
Dr. Trouard's research interest and activity is in the development and application of magnetic resonance imaging (MRI) and spectroscopy (MRS) for the study of interesting biological systems. MRI and MRS are powerful imaging tools that enable non-invasive investigation of structure and function in vivo. The focus of his research is the application of MRI and MRS to neurological function and disease. Current projects are investigating a variety of neurological diseases including Niemann-Pick Type C disease, Alzheimer's disease, stroke and cancer in both humans and in animal models.
• Urs Utzinger - Biomedical Engineering
Dr. Utzinger's research focus is on the development of optical techniques for the early diagnosis of tissue pathologies and monitoring of drug activity.
The research group's vision is to develop new technologies for tissue assessment that will increase performance of diagnosis, that are cost-effective, and that will increase access to health care.
• F. Ann Walker - Department of Chemistry
The Walker group has a wide range of projects, all of which fall under the general theme of gaining a better understanding of the heme centers in heme proteins that are vital to the life of almost all living organisms. The overall goals of this research are: 1) To evaluate the factors that affect the spectroscopic properties of the cytochromes, including heme substituents, heme reduction level, the nature of the axial ligands; 2) To characterize the nitrosylheme proteins from blood-sucking insects and simulate their behavior with model hemes; and 3) To investigate model hemes and heme proteins by multidimensional NMR spectroscopy.
• Diana Wheeler - Department of Entomology
Dr. Wheeler's research is centered on the physiological basis of caste differences in social insects, especially ants. The relevance of these physiological mechanisms to social organization, ecological interactions among colonies, and evolution of social systems is the primary interest of the research group. Areas of research include regulation of oogenesis, storage of proteins by adult workers and queens, mechanisms of sperm storage by queens, and caste determination.
• Joy Winzerling - Department of Nutritional Sciences
Dr. Winzerling's lab is interested in the effects of iron loading on intracellular iron metabolism and the promotion of cellular oxidative damage in various species and in human disease. A second area of clinical research they have initiated is the study of the effects of iron particulates, free radicals and related compounds in air pollution and cigarette smoke on oxidative damage of human lung cells. In addition to the work in humans, they have isolated and sequenced insect transferrins, ferritins and IRP1s from mosquitoes and moths; these insect proteins are similar to those of mammals. They are in the process of evaluating Manduca sexta as a potential biological model and also are studying the adaption of Aedes aegypti to iron loading provided during blood feeding.
• Michael Worobey - Department of Ecology & Evolutionary Biology
Dr. Worobey's research focuses on the evolution of viruses, particularly RNA viruses. He combines theoretical, methodological, and empirical approaches to use viruses to understand evolution, and to use evolution to understand viruses. His theoretical and methodological work focuses on the processes of recombination and natural selection, key evolutionary forces that shape the genetic diversity of viral populations. This work is motivated by specific biological questions including: (1) What role does recombination play in the evolution of insect-vectored pathogens like dengue virus? (2) When, where, and how did the viruses that cause AIDS originate? (3) Why was the 1918 “Spanish flu” pandemic so lethal? (4) What are the constraints on RNA virus evolution? (5) How can evolutionary insights lead to better HIV vaccines? These questions are being pursued primarily by using phylogenetic analyses of both publicly available sequence data and new data generated from field collections from the Democratic Republic of Congo and from archival tissue samples from around the world.
• Daniela Zarnescu - Department of Molecular & Cellular Biology
Dr. Zarnescu's long-term research interests lie in elucidating the molecular basis for cell polarity and how cellular asymmetry controls diverse processes ranging from neural development and synapse remodelling to cell division, growth and differentiation. To address these significant biological questions members of her lab are using a combination of genetic, cell biological and biochemical approaches in Drosophila melanogaster and various cell culture models.
• Konrad Zinsmaier - Arizona Research Laboratories, Division of Neurobiology
Dr. Zinsmaier is investigating fundamental molecular mechanisms that regulate synaptic structure and function, in particular neurotransmitter release, by undertaking a multidisciplinary approach, exploiting the neuromuscular junction of genetically modified Drosophila as a model system. Currently, his group's research interests fall into three categories: (A) Regulation of Ca 2+ triggered vesicle fusion and G protein-mediated inhibition of Ca 2+ entry by the CSP/SGT/Hsc70 chaperone system. Understanding the action of this regulatory complex in detail will be significant for a basic understanding of synaptic plasticity and for clinical research as CSP and Hsc70 have been linked to psychiatric disorders like manic depression. (B) Regulation of neuroexocytosis by the G protein receptors Methuselah and CIRL. Studies of Methuselah, in particular, show an intriguing relationship between excitatory neurotransmission, stress resistance, and aging. As a potential target of therapeutic drugs, studies of Mth and CIRL may ultimately lead to advances in detecting, treating, or even preventing neurological, psychological, or addictive disorders caused by pathologic transmission pathways. (C) The role of mitochondria for presynaptic function and plasticity. This genetic analysis provides new and unexpected insights for a basic understanding of presynaptic Ca 2+ homeostasis and Ca 2+ secretion coupling with significant implications for clinical research. (D) Regulation of microtubules structure at presynaptic nerve terminals by the small mitochondrial GTPase dMiro. This genetic analysis provides unexpected insights into the relation between mitochondrial transport and microtubules stability and could provide a model system for some forms of human spastic paraplegia.
(back to Faculty list | PERT home page)