Undergraduate Research Fellows Fall 2001

Laura A. Cathcart Goosecoid (gsc) Gene Expression in Cavefish MENTOR: Dr. William Jeffery, Department of Biology

Ngozi Nnennanya Ude Origin of Regenerated Serotonin Fibers in Spinal Cord of Lampreys MENTOR: Dr. Avis Cohen, Department of Biology

Lamprey is a primitive vertebrate which is capable of regenerating its spinal fibers. We are specifically interested in the regeneration of serotonin fibers which have previously been investigated in the Cohen laboratory. Serotonin is a neurotransmitter which acts at synapse between neuronal cells. The purpose of this experiment is to discover the origin of the regenerated serotonin fibers and the amount of descending serotonin fibers from the brain. In lampreys there are two possible sources of serotonin fibers, the brain or the spinal cord or both. The hypothesis states that regenerated serotonin fibers originate from the brain. To test this hypothesis, a mid body spinal crush will first be made in a lamprey. After degeneration and regeneration of serotonin fibers have been observed following the lesion site, a transection (cut) will be made in the spinal cord close to the brain. If this results in a disappearance of serotonin fibers, then it will be concluded that regenerated serotonin fibers originate from the brain. However, if the serotonin fibers are not affected by the second lesion, then this will imply that the regenerative serotonin fibers do not originate from the brain, but from the rostral segment of the spinal cord.

Sarah Evelyn Beck Use of Genetic Markers to determine the phylogenic relationship between the North Atlantic and North Pacific populations of E. glacialis MENTOR: Dr. Matthew Parsons Hare, Department of Biology

Brent Becker Optimizing the Reversal of LPS Toxicity Through Macrophage Fcy Receptor Types and IgG Isotypes MENTOR: Dr. David Mosser, Department of Cell Biology and Molecular Genetics

Alma Cano-Arnold Characterization of Rubricine and its components for genetic toxicity MENTOR: Dr. Spencer Benson, Department of Cell Biology and Molecular Genetics

Matthew R. Weaver Effects of Host Dispersal Capability on the Genetic Structure of Parasite Populations MENTOR: Dr. Robert F. Denno, Department of Entomology

In recent years, the field of nanotechnology has been expanding its resource base to include cooperative efforts with the fields of biology, chemistry, and virology. In particular, biological entities, such as viruses, have evolved complex assemblies of macromolecules that can potentially be used for the assembly of relevant nanoparticles. The unique structure and self-assembly of the Tobacco mosaic virus (TMV) make it an ideal template for the assembly wires, using soft metal ions.

Specific amino acids on the inner and outer portion of the protein subunit were identified as most likely to increase nanoparticle assembly once they were altered to increase surface charge affinity and hydrophobicity. Site-directed mutagenesis of the protein coding region of TMV was accomplished by a PCR-based method, using oligonucleotides that contained the desired mutations.

In the next phase of this project, the TMV particles will be incubated with gold, copper, silica, and other semiconductor materials to determine the binding efficacy of the mutated particles. The long term goal of this research is to use biomacromolecules to construct two and three dimensional nanocircuits for application in future computer chips and for other micro-electric devices.

Daniel Joseph Adams Preparation of an in vitro Model System for Studying Replication of Human Immunodeficiency Virus MENTOR: Dr. Jeffrey DeStefano, Department of Cell Biology and Molecular Genetics

Soroush Rais-Bahrami Linkage Disequilibrium in Colorado Potato Beetles MENTOR: Dr. David J. Hawthorne, Department of Entomology

Matilda Hagan Determining the Origin of the Regenerated Serotonin Fibers in the Lamprey Spinal Cord MENTOR: Dr. Avis Cohen, Department of Zoology

The lamprey is a small aquatic vertebrate whose central nervous system consists of fewer neurons than other vertebrates, which makes the lamprey an ideal model to study the neural basis of the complex operations of the central nervous system. Studies of the lamprey spinal cord have revealed that after spinal injury, serotonin containing neurons regenerate. Further research has demonstrated that change in temperature affects the functional outcome of regeneration (Cohen et al 1999). Animals who recover in warm conditions appear to have a higher functionality rate than animals that revive under cold conditions which is similar to their natural habitat. Preliminary work in the Cohen lab has showed that animals that recover under cold conditions appear to regenerate patchy serotonin distribution in contrast to animals that recuperate under warm conditions, which revive uniform distribution of serotonin fibers. Serotonin is known to slow down locomotion suggesting that there might be a correlation between the observed serotonin fibers and functional outcome of regeneration following spinal injury. The main point of interest is the observed serotonin fibers. Studies have showed serotonin fibers to disappear after spinal injury, then reappear. More fascinating is that the serotonin fibers in the most rostral caudal segment seem to increase following regeneration. The origin of these fibers is unclear, however it is known that the intrinsic serotonin fibers in the spinal cord do not regenerate. I propose to investigate the serotonin fiber distribution following a mid-body spinal crush and a high lesion that disconnects the brain from the spinal cord in animals that recuperate under cold conditions. I hypothesize that the observed increase in serotonin fibers originates from the brain and predict that the serotonin levels will decrease following the high lesion.

Jill Marie Ricker Tracing the Evolutionary History of tufA in Coleochaete MENTOR: Dr. Charles F. Delwiche, Department of Cell Biology and Molecular Genetics

Adrenalectomy (ADX} results in a reduction of food intake and body weight in lean and obese laboratory rats and mice. Subcutaneous implantation of cholesterol pellets containing 20% corticosterone (a glucocorticoid) reduces these effects. However, cholesterol/CORT pellets that contain higher amounts of CORT fail to promote circulating levels of CORT higher than those observed with the 20% pellet. We want to test the hypothesis that 11-b-hydroxysteroid-dehydrogenase (11- b HSD1 is an enzyme that converts corticosterone (CORT) to an inactive metabolite, 11-dehydrocorticosterone) is up regulated in rats that have high circulating levels of CORT.

ADX or sham-operated Sprague-Dawley rats will be implanted with cholesterol pellets that will vary in corticosterone concentration. Blood samples will be taken at several time intervals over a 4-day period. Corticosterone, 11-dehydrocorticosterone, 11 b HSD1, and mRNA ofthe enzyrne will be measured from plasma, liver, and kidney samples.

This proposed study examines the relationship between movement distance and direction coding mechanisms in the brain during the process of visuomotor adaptation. In order to determine if these mechanisms are either modular or interdependent, 40 subjects will be tested while they perform a visually guided reaching task that incorporates varying combinations of movement distance and direction distortions. Analysis of subjects' movement durations, initial direction errors (IDE), normalized jerk (fluidity of movement), and root mean square errors (smoothness of movement) over the course of the adaptation process will reveal the degree of interdependence between direction and distance coding mechanisms.

Sweet corn containing genes from Bacillus thuriengensis (Bt) express Cry1Ab protein which is specific to caterpillars. Although the protein expressed in pollen has no known toxicity to honeybees, studies have not addressed sublethal effects on bee behavior. This study will determine the effects of Bt sweet corn on the foraging ability of honey bees to find sources of food and communicate locations of these sources to other workers.

Pseudomonas syringae is a phytopathogenic Gram-negative bacterium that attempts to establish itself as a parasite by translocating proteins into host cells via a type III secretion system. Some of the injected proteins, however, may be recognized by products of plant resistance (R) genes and initiate a defense response. Bacterial proteins responsible for the betrayal are products of avirulence (avr) genes. The specificity of avr-R gene interactions can significantly influence the host range of a bacterial pathogen. In P. syringae, avr genes are located in the exchangable effector locus (EEL), a highly variable region of the Hrp pathogenicity island. P. syringae strains with different host ranges may contain distinct avr genes in their respective EELs. Conserved sequences flanking both sides of the EEL allow the use of PCR for amplification. If preliminary sequencing indicates that an EEL contains an unidentified avr gene, sequencing can then be completed. Once a unique avr gene has been sequenced, further study can determine the phenotypic effects the gene may have on other strains.

Many microorganisms of the domain Archaea live in extreme environments such as hydrothermal areas. These microorganisms are called hyperthermophiles. One example is Pyrococcus furiosus that grows optimally at 100¡C. In this environment its DNA undergo extensive damage, including mutation. When accumulated, these mutations will kill the cell. All DNA-based microorganisms, bacteria and eukaryotes, have a similarly low genomic spontaneous mutation rate resulting from the action of specific DNA repair mechanisms. No such repair mechanism has been found in any of the ten-archaeal genomes sequenced so far.

I propose to find out if the genomic spontaneous mutation rate in P. furiosus is similar to that of other DNA-based microbes, suggesting that P. furiosus has a novel system to repair spontaneous mutations. I will also obtain mutants with abnormally high mutation rates with the long-term goal to study DNA repair pathways in P. furiosus, and ultimately understand how hyperthermophiles can live in such extreme environments.

Microsatellites are tandem repeat units of a simple DNA motif and are used in a wide range of genomic research. I propose to study the relative mutation rates of four types of microsatellites (perfect, imperfect, short, long). I hypothesize that perfect microsatellites will exhibit greater mutation rates than imperfect and that longer microsatellites will exhibit greater mutation rates than shorter. To test these hypotheses I will select eight different loci that are representative of these four types of microsatellites and test each one on eight individuals from a population of the stalk-eyed fly Cyrtodiopsis dalmanni.

Kimberly Wessells A molecular investigation of the influence of quorum sensing on rugose formation by Salmonella typhimurium DT104 MENTOR: Dr. Sam W. Joseph, Department of Cell Biology and Molecular Genetics

Salmonella typhimurium DT104 is an emerging pathogenic strain of enteric bacteria. It is a principle cause of gastroenteritis in the United States and exhibits widespread antibiotic resistance. S. typhimurium possesses numerous survival mechanisms which enhance its ability to thrive under adverse conditions. One such mechanism is the formation of rugose colonies at 25¡C, a morphological change. The presence of rugose colonies is correlated with the presence of an extracellular substance encapsulating the cells and the ability to aggregate. Rugose colonies exhibit an increased resistance to acid, salt, chlorine and oxidative stress. These are conditions that are potentially experienced in the transition between host and external environment. Initial studies have demonstrated that the formation of rugose colonies is density dependent. Gram negative bacteria, such as Salmonella spp. engage in cell-to-cell communication, called quorum sensing. Autoinducer signaling molecules control gene transcription as a function of cell density. This project will attempt to determine if autoinducer production affects rugosity. The second goal is to determine where, and at what point, the autoinducer affects the genetic pathway regulating rugose formation.

Programmed Cell Death (PCD) is a fundamental process that eliminates obsolete cells and allows organisms to develop properly. Defects in PCD are known to cause tumors, birth defects, and neurodegenerative diseases. In Drosophila, the steroid hormone 20hydroxyecdysone (ecdysone) triggers metamorphosis. During metamorphosis, ecdysone activates larval tissue destruction by PCD and adult imaginal tissue differentiation. During this process, the steroids are bound by a receptor complex that induces chromosome puffs, sites of active gene transcription. Previous research has shown that the ecdysone regulated E93 gene, that was isolated from the 93F puff, is an important gene in the PCD pathway. I propose to analyze other chromosome puffs with similar characteristics as 93F to identify another gene involved in PCD.

Jessica Chiles Hydrophobic self-assembly MENTOR: Dr. Lyle Isaacs, Department of Chemistry and Biochemistry

The hydrophobic effect is important in biological systems, such as protein folding, protein-protein interactions, and lipid bilayer membranes. The hydrophobic effect results from the interactions between molecules with large apolar regions. Selfassociation in water is not well understood in contrast to the highly directional and predictable interactions of hydrogen bonds and metal-ligand interactions in non-polar solvents. The Isaacs group is investigating the use of glycoluril as a building block for the construction of self-complementary, facially amphiphilic molecules. With supervision I have synthesized a molecule suspected to possess these amphiphilic characteristics and with further research the association and thermodynamic properties can be determined. By determining trends in structural and thermodynamic properties of these molecules, it may be possible to deduce more general rules for self-association in aqueous solution.

The recycling of iodide is an integral homeostatic function for many higher organisms including mammals. This salvaging of iodide is believed to occur by the deiodination of mono- and diiodotyrosine, a process catalyzed by the enzyme iodotyrosine deiodinase. This enzyme, although essential to survival, remains relatively uncharacterized. This proposal describes a characterization of the enzyme active binding site by studying the binding affinity as well as the binding mechanism of substrate and transition state analogues. Analogues that behave as competitive inhibitors will be evaluated by their effects over a range of substrate concentrations. Compounds that exhibit a mixed pattern of inhibition will be compared by their concentration required to inhibit 50% of the standard enzyme turnover. Characterizing the binding site of the enzyme is an important first step in understanding the mechanism of catalytic deiodination.

Prograrnmed cell death is important for the proper development of all higher organisms. Although tremendous progress has been made in understanding how cell death is regulated, the identity of many proteins has yet to be determined. I propose to study this pathway during steroid-regulated destruction of Drosophila melanogaster salivary glands by profiling the proteins present before and during cell death. Samples will be collected using standard protein extraction techniques and then analyzed by two-dimensional SDS polyacrilamide gel electrophoresis (SDS-PAGE) and finally matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

This series of experiments will provide the equilibrium and kinetic properties of the folding transition of the SH3 domain of a-spectrin. These properties will be determined as functions of three environmental variables, pH, temperature, and urea concentration. The series will include seven pH values, approximately ten temperatures, and seven urea concentrations. All possible combinations of these variables will be included. This free energy surface will be used to determine suitable experimental conditions for future experiments (NMR-detected hydrogen/deuterium exchange).

Fungi are pathogens of both animals and plants. A significant factor in both is the ability of the fungus to tolerate antifungal compounds, such as antibiotics used to treat animals or natural defense compounds in plants. Studying the regulation of resistance genes in plant pathogenic fungi provides an understanding of the ways that fungi can evolve resistance. The pea pathogen Fusarium solani (also a human pathogen) is able to detoxify an antifungal isoflavonoid compound, pisatin, produced by the host plant. Expression of a cytochrome P450 pisatin detoxification gene (PDA1) is triggered by the exposure of mycelium to pisatin. A 40 bp sequence in PDA1 is responsible for pisatin induction. A protein (PRF) that binds this site has also been identified along with its gene sequence. The aim of my project is to test the hypothesis that this PRF protein acts as a nuclear receptor, binding both pisatin and the 40 bp DNA site. Function of this protein as a nuclear receptor would be significant in identifying the signaling pathway for the control of this resistance gene.

The aim of this research is to determine the levels of mariner transposase transcription in transgenic Aedes aegypti and correlate them with mariner transposition rates.

Interferon-t (IFN-t) is a type-I IFN secreted by the ruminant conceptus to maintain pregnancy and inhibit endothelial disintegration. Therapeutically it has been noted that among the type-I IFNS, IFN-t has a decreased incidence of side effects and toxicity to cells while maintaining relatively equivalent potency to that of IFN-a in its antiviral and antitumor activity. It is believed that reason for this difference is related to the pathways within the cell each IFN activates. This study will examine and clarify these differences by studying the effects of IFN-a, IFN-t and six mutations of IFN-t on human fibroblast cell lines lacking specific IFN signaling components. The results will yield a greater understanding of the vital components of the IFN structure as well as the intennal signaling pathways associated with cytotoxicity.

A better knowledge of how the ear has adapted to a deep-sea environment will assist in understanding the evolution of the inner ear and the implications of ear morphology on its function. Prior studies have shown several kends in the anatomy of certain deep-sea species, such as elongated stereocilia bundles and enlarged saccules in sound-producing fish. This study will attempt to confirm these prior observations and look for general anatomical trends among the species studied. An effort will be made to identify the evolutionary forces driving these adaptations and explain the function these adaptations serve in the organism.

The main objective of this project is to elucidate the mechanisms of viral pathogenesis and resistance in plants. Specifically, the role of three candidate host factors in viral pathogenicity will be investigated. These host factors were isolated from an Arabidoposis cDNA library and found to interact with the Tobacco mosaic virus (TMV) helicase protein. Thus, they may play an important role in virus replication and disease development. For the proposed study Potato virus X(PVX) constructs will be engineered to over-express the three host genes found to interact with the TMV helicase protein. Once PVX mutant vectors that produce infective transcripts are developed they will be used to inoculate N. betshemiana. The plants will be observed for symptom development and necrotic leaves assayed for the accumulation of the test gene products to confirm their role in any observed host responses.

Normal development of the visual system is dependent upon visual experience. However, the influence of visual experience on this development is confined to the first few weeks of postnatal life in mice, called the "critical period." Previous experiments have suggested a role for brain-derived neurotrophin factor (BDNF) in the early postnatal development of the visual system. The proposed experiments are designed to further elucidate the role of BDNF in early development and the regulation of the critical period. This will be accomplished by studying transgenic mice that overexpress BDNF and examining how NMDAR composition is regulated by various types of visual experience, such as dark-rearing. These experiment will increase our understanding of the complex processes that occur during early postnatal development in order for the visual cortex to develop normally to full maturity.

Meghan Burke Studies on the effects of apoptosis inhibitors on cytotoxicity due to sulfer mustard MENTOR: Dr. Elizabeth Quinlan, Department of Biology

The objective of this project will be to study the involvement of the mitochondrial and the CD95 receptor pathways in Sulfur Mustard (HD)-induced programmed cell death, or apoptosis. We want to better understand the Sulfur Mustard(Hd) induced apoptosis pathways because sulfur mustard is used today as a chemical warfare agent that causes skin blisters. Apoptosis, or cell death, will be measured by a Caspase-3 assay.

Nesseria gonorrhoeae is the causative agent of gonorrhea, one of the most prevalent STDs in the country. These gram-negative diplococci primarily infect the mucosal linings of the urogenital tract in men and women. Disseminated infections can lead to secondary conditions like infertility, particularly in women. Attempts to study the pathology and the immune response to the infection have been hindered by a lack of a suitable animal model for the disease, as N. gonorrhoeae is a strict human pathogen. A mouse model for gonococcal infection has recently been developed. The major goal of this study is to use this mouse system to characterize the local mucosal immune response to gonococcal infection. This study will greatly increase our understanding of gonorrhea disease process and may provide new strategies for the prevention and treatment.

Carl R. Eby III An Investigation Of The Potential For Striped Blenny (Chasmodes bosquianus) Predation To Control Predation By The Polyclad Turbellarian Stylochus ellipticus On The Eastern Oyster Crassostrea virginica MENTOR: Dr. Kennedy Paynter Jr., Department of Biology

The polyclad turbellarian Stylochus ellipticus is known to be a predator of the Eastern Oyster Crassostrea virginica in the Chesapeake Bay. S. ellipticus primarily feeds on juvenile oysters (spat) and has the potential to change the oyster reef community structure by removing juvenile oysters which, by their growth, create habitat. With the potential to produce upwards of 39,000 eggs over a 48hr period, S. ellipticus can reach epidemic proportions in relatively short time. Trophic interactions were investigated between the striped blenny (Chasmodes bosquianus) and S. ellipticus for the ability of C. bosquianus to possibly control populations of S. ellipticus. When single blennies were housed with three flatworms in a 2.0L tank, the average predation of flatworms in a 12hr period was 74.997% (SE 1.137, P-value <. 0001). These data suggest that C. bosquianus may play an important role in the control of S. ellipticus. By preying upon S. ellipticus, the striped blenny may secure its own future and the future of its offspring by ensuring the growth of the oysters which will form the future habitat.

Elizabeth Flynn A Characterization of Ideal Habitat Structure for the Striped Blenny, Chasmodes Bosquianus MENTOR: Kennedy T. Paynter Jr., Department of Biology

The science of restoration ecology is still in its infancy. While it is generally accepted that biological diversity increases with habitat heterogeneity, the relationship remains largely untested in a restoration context. This research investigates the assumption that habitat selection decisions are significantly affected by habitat structure. The striped blenny, Chasmodes bosquianus, was chosen as the study species because of its importance in the Chesapeake Bay food web and its high association with oyster reefs. Identification of relevant habitat structure and the examination of that structure on a scale relevant to C. bosquianus are critical steps in understanding how reef restoration efforts impact Bay populations.

Elinor Lichtenberg Shaking Your Booty: Abdominal Oscillations and Status Discrimination in Stalk-eyed Flies MENTOR: Dr. Gerald Wilkinson, Department of Biology

Use of vibrations for signalling is widespread among insects, and appears to occur in several species of stalk-eyed flies (Diptera: Diopsidae). The Malaysian stalk-eyed fly Cyrtodiopsis whitei frequently exhibits abdominal oscillations while aggregating on root hairs at dawn and dusk. In the laboratory, such oscillations can also be seen when two individuals of the same sex fight over food or females. Bobbing behavior was studied by videotaping staged fights between two flies, either of the same sex or of opposite sexes.

Esteban Carrizosa Correlation of the the presence of 5-methylcytosine and spontaneous mutation frequencies in the context of nfsB, a nitroreductase gene, in the human pathogen Neisseria gonorrhoeae MENTOR: Dr. Daniel Stein, Department of Cell Biology and Molecular Genetics

The human pathogen Neisseria gonorrhoeae is responsible for the disease gonorrhea, and may cause complications such as pharyngitis, and pelvic inflammatory disease. Because of the differences in the anatomic sites this organism infects, N. gonorrhoeae must be able to alter its DNA in such a way as to be able to infect the correct site at the correct time, suggesting that the organism should be able to mutate its DNA at a relatively high frequency. Furthermore, the genome of the gonococcus contains a relatively high percentage of a modified version of cytosine, 5-methylcytosine, which can spontaneously convert to thymine. This also suggests that the organism must have a fairly high mutation frequency. However, observations indicate that the organism is hypomutable, not hypermutable. Consequently, the gonococcus probably has some novel DNA repair system designed to deal with deamination of 5-methylcytosine. I have begun research to study the correlation between the presence of 5-methylcytosine and mutation frequencies in N. gonorrhoeae in the context of a nitroreductase gene, nfsB. This gene serves as a convenient reporter system for studies in mutation frequencies. Strains with functional copies of this gene are sensitive to the antimicrobial agent nitrofurantoin (and related compounds), whereas mutants are resistant. I have conducted experiments to determine the minimum inhibitory concentration of nitrofurantoin, and I have sequenced the nfsB gene in various spontaneous mutants. I have also conducted biochemical assays to compare the activity of NfsB, the nfsB protein product, in wild type and nfsB mutant strains.

Yana Tsygansky Connexin expression during the development in bird auditory structure MENTOR: Dr. Catherine Carr, Department of Biology

The development of the auditory system can be examined using a variety of organisms because auditory structures are highly conserved among many animals. In particular, birds have proven to be an extremely useful model to study auditory development. These avian studies have indicated great significance in a structure located in the hindbrain known as the nucleus laminaris (NL). Though this structure is involved in sound localization, little is known about the process of its development. One possible mechanism involved in auditory development depends on gap junctions. These intracellular connections are made up of a family of proteins called connexins, which are well known, and antibodies against them are widely available. The preliminary studies indicated the recognition of connexins26, 32 and, 43 throughout avian brain. In order to study in detail the location of these connexins and the exact timing of their appearance in the auditory structures, I investigated the expression of connexin in chicken model using immunohistochemistry method.

Natalie Dye Development of an in vivo exonic splicing enhancer activity assay MENTOR: Dr. Stephen M. Mount, Department of Cell Biology and Molecular Genetics

We have designed a system that tests short sequences for the ability to enhance pre-mRNA splicing in vivo. Identifying exonic splicing enhancers (ESEs) will not only help to clarify the mechanism behind splice site selection, but also enable more accurate prediction of mRNA, and therefore protein, sequences from the genomic sequence. The assay is based on a choice between inclusion and skipping of an exon. Our goal is to create a vector such that the exon will be included in the mature mRNA if the test sequences function as an enhancer, but the exon will be skipped if they do not.

Historically, complex oxides have been created through the use of extremely high temperatures in excess of 1000 ¡C. Due to the high temperatures, the oxides rearrange to the most thermodynamically stable form. Due to the lack of kinetic control, the types of oxides formed are significantly limited. Reactions have been developed at much lower temperatures that would bring the reactions under kinetic control. The thermodynamic rearrangements do not occur under low temperature conditions, which permit the development of new and possibly useful compounds. This class of compounds is not thermodynamically stable and is termed metastable. In other words, by drastically lowering the reaction temperatures, one can introduce functionalized organic or bioorganic molecules into the structure. The complex oxides targeted in this study, perovskites, are composed of three layers with cations in-between each of these layers. Theoretically, these cations can be removed and replaced with other molecules. These ion exchange or condensation reactions occur at low temperatures. This study focuses on the Ruddlesden-Popper type perovskite K2La2Ti3O10, and the metastable oxide La2Ti3O9.

Christian Reusche Studying the expression of At4g24260, a membrane-bound cellulase, in Arabidopsis thaliana MENTOR: Dr. Elena del Campillo, Department of Cell Biology and Molecular Genetics

Out of 25 cellulase genes present in the Arabidopsis genome, there are 3 cellulase genes that are unique because they have a transmembrane domain toward the N-terminal end. These membrane-bound cellulases are speculated to play an important role in plant growth as they can modify the primary cell wall from the inner most layers of the wall. My project entails studying the membrane-bound cellulase At424260, located on chromosome 4 of Arabidopsis thaliana and the first question addressed, is the At4g24260 tissue specific expression.

Jessica Nelson Biology and Management of the Cereal Rust Mite on Timothy MENTOR: Dr. Galen Dively, Department of Entomology

The cereal rust mite (Abacarus hystrix) is a major new pest on timothy in Maryland. Studies have been conducted to gain a better understanding of its biology and management. Monthly sampling in a representative number of fields have shown that the rust mite is cold-adapted, actively reproducing during the winter and reaching peak density in April. Various cultural practices are being tested to reduce the overwintering survival and spring build-up of mite populations. Late fall harvest and early spring applications of herbicides have been shown to reduce mite numbers. Laboratory and field tests have shown that all timothy varieties grown in Maryland are susceptible. However, perennial grasses, such as reed canarygrass, are resistant to the mite and could be planted as an alternative to timothy. These studies will lead to the development of management recommendations for timothy growers in the state.

Naser Jaleel Analysis of Structure-Function Relationships in Ornithine Transcarbamylase MENTOR: Dr. Norma Allewell, Department of Chemistry and Biochemistry

Ornithine transcarbamylase (OTCase) is a homotrimeric enzyme that catalyzes the formation of citrulline from ornithine (ORN) and carbamyl phosphate (CP). Two plant OTCases (ClOTC1 and ClOTC2) have been identified with different substrate specificities, with ClOTC2 preferentially binding to canaline, an isomer of ORN. This study is aimed at understanding the structure-function relationships in the OTCase enzyme by elucidating the differences between the evolutionarily divergent plant and human OTCase.

A. Michael S. Sheer Genetic Analysis of Speciation Genes in Two Populations of Pea Aphids. MENTOR: Dr. Sara Via, Department of Biology

Sarah Nourse Investigation of Human Mitochondreal Ornithine Transporter and Interactions with Ornithine Transcarbamylase. MENTOR: Dr. Norma Allewell, Department of Chemistry and Biochemistry

Ebrahim Paryavi Expression and in Vivo Function of an Arabidopsis Cellulase Gene with a Putative Cellulase Binding Domain. MENTOR: Dr. Norma Allewell, Department of Chemistry and Biochemistry

Avni A. Shah Ethylene hormone response: Does the ETR1 ethylene receptor communicate to other ethylene receptors in the plant Arabidopsis thaliana? MENTOR: Dr. Caren Chang, Department of Cell Biology and Molecular Genetics

David Barse The Effects of Monocular Deprivation on Post-synaptic Glutamate receptors in the rat visual cortex. MENTOR: Dr. Elizabeth M. Quinlan, Department of Biology

Hawaa Almansouri A Study of the Frequency and Origin of the FMF Disease in Meditteranean Populations. MENTOR: Dr. Sarah Tishkoff, Department of Biology

Michael TerAvest Survival Strategies of Dampwood Termite Colonies. MENTOR: Dr. Barbara Thorne, Department of Entomology

Hojun Li Synthesis and Characterization of Artificial Ion Channels. MENTOR: Dr. Jeffery Davis, Department of Chemistry and Biochemistry

Amirparviz Davoody Ceramide Channels in Apoptosis. MENTOR: Dr. Marco Colombini, Department of Biology

Katie C. Bittner Polymerization of Yeast Actin. MENTOR: Dr. Sandra Greer, Department of Chemistry and Biochemistry

Dan Gozhansky Host Plant Associated Genotypes of the Fall Cankerworm, Alsophila pometeria, Within and Across Habitats. MENTOR: Dr. Pedro Barbosa, Department of Entomology

Madhumitha Nandakumar RNAi as an Antiviral Immune Response in Drosophila Cells. MENTOR: Dr. Louisa Wu, Center for Agricultural Biotechnology, UMBI

Joseph P. Hickey Single-Molecule Spectroscopic Studies of Vesicle-Nanoparticle Interaction. MENTOR: Dr. Douglas S. English, Department of Chemistry and Biochemistry

Matthew J. Elrick Structural Studies of the RB Interactive Domain of BRCA 1. MENTOR: Dr. Jin Shan Hu, Department of Chemistry and Biochemistry

Faten Deeb Kinesin Function During Spermiogenesis in the Water Fern, Marsilea vestita. MENTOR: Dr. Stephen M. Wolniak, Department of Cell Biology and Molecular Genetics