NMTBiologyAbstracts

Tamara Hartenberger, graduate student

Dr. Scott Shors, advisor

My research under Dr. Shors involves investigation of the role of the proteins TIA-1 (T-cell intracellular antigen) and TIAR (TIA-related) in the cellular response to viral infection. Specifically, we are investigating whether the proteins TIA and TIAR preferentially interact with viral RNA to inhibit viral replication. During cellular stress, as in the case of a viral infection, infected cells will release the protein interferon (IFN), with the ultimate result that protein synthesis within other infected cells is shut down. One role of the proteins TIA and TIAR is to shuttle the non-translated mRNA of an infected cell, along with non-functional translation initiation complexes, into cytoplasmic inclusions known as stress granules.

We are attempting to determine whether viral protein synthesis, along with host protein synthesis, is shut down in an infected cell. Further, we want to investigate what role, if any, the proteins TIA and TIAR play in mediating an anti-viral response within a cell. To that end, we are currently growing and will use three different lines of mouse embryo fibroblast (MEF) cells in culture for infection: wild type (WT) MEF, with both functional TIAR and TIA genes; TIAR -/- MEF, lacking a functional TIAR gene; and TIA -/- MEF, lacking a functional TIA gene. In the presence or absence of IFN, we will infect each of these cell lines with viruses representing a variety of viral families: EMCV (a picornavirus), VSV (a rhabdovirus), vaccinia virus (VV) (a pox virus), Herpes Simplex Virus 1 and 2 (), and hepatitis (). To measure viral output from each of these situations, we will use plaque assays and titer virus in either Hela cells or MEF.

Hi, I am a graduate student of Dr. Scott T. Shors and Dr. Snezna Rogelj. My research is of the Drug Discovery Team, a collaborative research project with Dept of Chemistry, That is developing novel antiviral, antibacterial and cancer drugs. I am currently working on MTT ASSAY, a quantitative colorimetric assay for measuring the effect of candidate drugs on cellular proliferation, viability and cytotoxicity. This assay is based on the reduction of yellow tetrazolium salt, MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide)) into water insoluble, dark blue formazan crystals. This cleavage takes place only in metabolically active cells by the mitochondrial succinate dehydrogenase enzyme. The resulting intracellular formazan can be solubilized and quantified by spectrophotometric means which directly correlates to the number of living cells. I am also testing these drugs for antiviral activity via plaque reduction assay.

Delta-9-Tetrahydrocannabinol (THC) a psychoactive compound has been isolated from the marijuana (cannabis) plant and used for therapeutic and recreational purposes for thousands of years. We have previously found that exposure of ex-vivo lymphocytes and neutrophils induces shedding of L-selectin, a cell-surface adhesion molecule that plays an important role in inflammation. Using DNA laddering and flow cytometric analysis, I am now studying induction of apoptosis and necrosis by THC in primary and immortalized leukocytes. Our results suggest that THC may exert its immunosuppressive effect at least in part through induction of lymphocyte apoptosis and necrosis. I am also conducting similar studies with Tamoxifen, an anti-cancer drug.

Bacitracin is a peptide antibiotic produced by certain Bacillus species which inhibits proper cell wall formation in other gram positive bacteria. Our lab has found that commercial preparations of bacitracin contain degradative enzymes including DNAse, protease, RNAse and a beta-glucanase. My primary goal is to purify and characterize the protease. Preliminary characterization shows that the protease is unaffected by treatment with denaturing agents such as NaCl, guanidine HCl, heat, and SDS; in fact, proteolytic activity of bacitracin solutions is enhanced in the presence of SDS, possibly due to dissociation of an inhibitory bacitracin/protease complex. In order to purify the protease, bacitracin is chloroform extracted followed by size exclusion chromatography and SDS-PAGE. Bands suspected to contain the protease are analyzed by mass spectrometry to identify the contents. So far, MS analysis has confirmed the presence of a Bacillus subtilis beta-glucanase.

We are studying CD4, the lymphocyte plasma membrane receptor for HIV. It has been shown that HIV entry into the cell is dependent on the redox status of CD4's domain 2 disulfide bond.

Using an antibody that is specific for either reduced or oxidized CD4 domain 2, we are investigating the effect of intracellular levels of glutathione and antioxidants like alpha lipoic acid on the redox

status of domain 2 in Jurkat cells. We hope to elucidate one possible mechanism why the dietary supplement alpha lipoic acid appears to benefit HIV patients.

I use Scanning Electron Microscopy, Transmission Electron Microscopy and Light Microscopy to visualize the ultra-structure of various biological and non-biological materials. For example, I am looking at the structure and composition of both naturally occurring and in-laboratory-grown biofilms and am, simultaneously, assessing the effects of various enzyme treatments on these materials. In addition, I participate in other projects that require microscopic analysis; this includes pathogen detection and carbon nanotube solubilization and functionalization.

Salt cedar trees were introduced into the Western United States in the late 1800s for shading and flood control along river banks. Shortly after their introduction, Tamarix trees became rapidly invasive, particularly on disturbed or moist soils. My thesis project involves analysis of phenotypic variation among numerous stands of T. chinensis and T. ramossissima in various regions throughout New Mexico, primarily along the Rio Grande and Pecos rivers. The overall intent will be to examine the genetically-based phenotypic variability of these environmentally threatening plants. Experimental methods will primarily consist of common garden and seed germination procedures.

Seeds will be collected from several stands along the Rio Grande and Pecos rivers in order to identify the role of environmental factors such as climate, elevation, and humidity on phenotypic variability in the salt cedar. Plants taken from different regions may have acquired slightly different adaptations to their specific habitats, and growing plants in a common environment will identify these traits.