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Cellular, molecular and developmental biology.

Chair: Sandra Leal, University of Southern Mississippi

Vice-chair: Vijay Rangachari University of Southern Mississippi

THURSDAY MORNING

Room 216

Environmental Science, Microbiological Science, and Infectious Disease

O2.01

8:30 CHARACTERIZATION OF A NOVEL BACTERIAL MICROCOMPARTMENT SHELL PROTEIN IN THE CARBON-FIXING

ORGANISMS PROCHLOROCOCCUS MARINUS AND HALOTHIOBACILLUS NEAPOLITANUS

Evan Roberts (1), William Hirst (2), Sabine Heinhorst (1), Gordon Cannon (1)

(1) University of Southern Mississippi, (2) Vassar College

Specialized organelles, known as bacterial microcompartments (BMCs), are being discovered in an increasing number of bacterial species, where they participate in various metabolic processes. Cyanobacteria and certain chemoautotrophs contain

BMCs known as carboxysomes, which sequester carbon dioxide inside a polyhedral shell that is comprised entirely of protein. Enclosed within the carboxysome interior is the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). RubisCO catalyzes the first step in the Calvin-Benson-Bassham Cycle, which converts inorganic carbon dioxide into organic cellular precursors. To understand how the structure of the carboxysome relates to its function, it is necessary to characterize the full complement of carboxysome shell proteins. In this study, the double domain BMC protein CsoS1D from the chemoautotrophic sulfur bacterium Halothiobacillus neapolitanus was expressed recombinantly and used to generate a polyclonal antibody. A carboxysome purification procedure was developed for the marine cyanobacterium Prochlorococcus marinus MED4, and the carboxysome protein composition was characterized by one- and two-dimensional gel electrophoresis. The CsoS1D protein co-purified with purified carboxysomes of both bacteria during centrifugation on a sucrose gradient and was found to be associated with the shell, as shown by immunoblotting with species-specific anti-CsoS1D antibodies. Our finding suggests that the carboxysome composition is likely more complex than was previously assumed based on the gene complement of the classical carboxysome operon.

O2.02

8:45 THE ROLE OF THE PORES IN THE CARBOXYSOME SHELL IN METABOLITE FLUX

Jenifer Milam (1), Balaraj Menon (1), Fei Cai (2), Seth Axen (2), Cheryl Kerfeld (2), Gordon Cannon (1), Sabine Heinhorst (1)

(1) University of Southen Mississippi, (2) Department of Energy Joint Genome Institute

The carboxysome, a polyhedral protein microcompartment found in all cyanobacteria and in many chemoautotrophs, is filled with ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), the enzyme that catalyzes the fixation of C[O.sub.2] onto ribulose-1,5-bisphosphate and produces two molecules of 3-phosphoglycerate. Although it is well established that RubisCO derives a catalytic advantage from compartmentalization, the molecular mechanism by which its substrates and products traverse the carboxysome shell is not well understood. The central pores formed by the hexameric assemblies of the major shell proteins, multiple CsoS1 paralogs, have been implicated in facilitating the flux of metabolites into and out of the carboxysome interior. To assess the role of the pores in metabolite transfer, we have made use of structural models to target key residues in the conserved pore motif of CsoS1A for mutagenesis. The hexamers of the resulting CsoS1A mutants are predicted to form pores of different shape, charge or diameter. Mutant constructs have been generated and have been used to replace the wild type allele in H. neapolitanus. Genotypic and phenotypic characterizations of the H. neapolitanus csoS1A pore mutants are underway in preparation for an assessment of structure and function of their carboxysomes.

O2.03

9:00 MICROARRY ANALYSIS OF KARENIA BREVIS GENE EXPRESSION PATTERNS IN RESPONCE TO SALINITY DIFFERENCES

David Jayroe, Timothy McLean

University of Southern Mississippi

Karenia brevis is a toxic marine dinoflagellate that causes harmful algal blooms (HABs), also known as red tides, in the Gulf of Mexico. Red tides occur nearly annually off the coast of Florida and Texas. These red tides almost never occur along the Alabama, Mississippi, and Louisiana coastlines in the northern Gulf--only a single red tide event has been documented in these waters and was believed to be a result of a tropical storm transporting an existing bloom northward. One hypothesis states that the absence of blooms in the northern Gulf is due to lower ambient salinity, primarily from Mississippi River discharge, which limits K. brevis growth. We investigated this hypothesis by culturing K. brevis in the laboratory under a variety of salinity regimes. Some cultures were kept growing in high salinity (open ocean) media, and others were diluted and allowed to acclimate to lower salinities. These salinities spanned a range of 32 parts per thousand (ppt) to 19 ppt. After a 7-day incubation, cells were harvested, and total RNA was extracted for analysis on a K. brevis-specific microarray. Once the microarrays have been scanned, we will be able to identify which genes are being differentially expressed due to the changing salinity, that, in turn, will allow for a better understanding of growth potential and regulation under those specific environmental circumstances. Additionally, the data will enhance our emerging efforts to increase transcriptomic annotations, create gene clusters, and build gene regulatory network models for this environmentally and economically important organism.

O2.04

9:15 ROLE OF SELENOPROTEIN M IN GULF COAST TICK(AMBLYOMMA MACULATUM)

Parul Singh, Rachel Truhett, Shahid Karim

University of Southern Mississippi

The Gulf-coast ticks transmit diseasecausing pathogens to humans and animals. Rickettsia parkeri is notable among the pathogens transmitted by A. maculatum to humans. Heavy infestations of A. maculatum on animal ears cause it to become thickened and curled, a condition commonly called "gotch ear". The tick's multifunctional salivary glands are vital to their biological success and likely also play a critical role in transmission of disease; tick saliva contains a broad array of secretory products that facilitate prolonged tick attachment and feeding, disrupting tick blood feeding or inactivating key tick salivary proteins presents a novel strategy for tick-borne disease prevention. Sequencing of A. maculatum salivary gland normalized cDNA library revealed a gene sequence homologous to Selenoprotein M. Trace element Selenium exhibits a variety of functions in the form of Selenoproteins, most importantly, as an antioxidant enzyme. Selenoprotein M is expressed in A. maculatum salivary glands in almost all the feeding phases. RNA interference (RNAi) was used to assess the role of this molecule for tick feeding success. Silencing of was demonstrated by reduced transcript in salivary glands removed from partially fed ticks. Disrupting expression of Selenoprotein M by RNAi induced rapid weight gain in engorging female ticks in early phase of feeding.Since many Selenoproteins are involved in anti-oxidant activities, we further evaluated the anti-oxidant capacity of tick tissues treated with SelM-dsRNA. There was a significant reduction in the antioxidant capacity in Selenoprotein M silenced tick tissues.

O2.05

9:30 EHRLICHIA CHAFFEENSIS AND ITS INTERACTION WITH TICK SALIVARY GLANDS

Rachel Truhett, Shahid Karim, Laila Ali, Parul Singh

University of Southern Mississippi

Ticks are an example of ecto-parasites that steal blood, a source of nutrients, from their vertebrate hosts for prolonged periods of time. Our experiment is an attempt to develop a weight-based sex differentiation tool for RNAi and in vitro pathogen infections among the adult females. The relationship between weights of engorged nymphs and their adult sexes in Amblyomma americanum was addressed in this study. Flat nymphs were fed to complete repletion on New Zealand white rabbits, weighed individually and divided into groups based on their weight, and kept until they molted. This suggests that nymphs of this species that become female presumably imbibe more blood than those that became male. To further confirm, we inoculated an obligate intracellular bacterium, Ehrlichia chaffeensis Arkansas strain infected DH82 cells in the heavier engorged nymphs and kept them for molting at 34[degrees]C and 90% relative humidity. Freshly molted adults were used to test the E. chaffeensis infection rate. E. chaffeensis genomic DNA was extracted from individual unfed and partially fed midguts and salivary glands. The tissue samples were tested for the presence of E. chaffeensis using nested Polymerase Chain Reaction (PCR). PCR amplified fragments were detected in unfed and partially fed tissues. Our experiment demonstrated successful E. chaffeensis infection of female adult salivary glands for our proposed RNAi studies. Using various gene specific primers, we tested transcriptional expression of selected salivary genes in the clean and E. chaffeensis infected tick's salivary glands. Our results demonstrated the differential expression of selected gene transcripts in infected glands.

O2.06

9:45 TICK INFESTATIONS AND THEIR CONSEQUENCES FOR MIGRATORY SONGBIRDS DURING SPRING STOPOVER

Michael Sellers, William D'Angelo, Shahid Karim, Frank Moore

The University of Southern Mississippi

Migratory birds encounter a host of challenges when making their yearly journey from tropical wintering grounds to temperate breeding grounds. One is exposure to parasites and pathogens. During the spring of 2009 and 2010, landbird migrants were visually surveyed for tick infestation when they stopped over at our Johnson's Bayou, LA, study site following migration across the Gulf of Mexico. In that time, 2,012 birds were sampled. In 2009, eight individuals among six species were infested out of the 312 captured birds (2.3% of the captured birds were infested with one or more ticks). In 2010, 42 individuals among 19 species were infested out of the 1,713 that were sampled (2.5% of the captured birds). The collected ticks and blood samples of infested and "focal" species had genomic DNA extracted and analyzed via PCR to determine if pathogens are present, if transmission is occurring, and which bird species are more likely to acquire and transmit ticks and tick-borne diseases. Currently, we have determined that Ehrlichia chaffeensis is present in some of the infesting ticks. We are also identifying ticks in relation to their origin. Weekly ground surveys using a drag cloth produced no ticks; therefore, the birds are likely to have arrived with them after crossing the Gulf of Mexico. Preliminary results show that some of the collected ticks are not native to North America. The energetic condition, including body mass and fat, are being analyzed in relation to tick infestations to assess impact on the stopover biology of the migratory birds.

10:00 BREAK

Biomedical Research: Cancer, Oxidative Stress, and Heart Disease

O2.07

10:15 THE RESPONSE OF TAMOXIFEN-RESISTANT AND TAMOXIFEN-SENSITIVE BREAST CANCER CELL LINES TO HET0016 ALONE OR IN COMBINATION WITH OTHER CHEMOTHERAPEUTICS

Barak Gunter (1), Tiffani Slaughter (1), Fan Fan (1), Chenghui Huang (1), Antonio Pannuti (1), Rodney Baker (1), John Falck (2), Lucio Miele (1), Richard Roman (1), Roy Duhe (1)

(1) University of Mississippi Medical Center, (2) The University of Texas Southwestern Medical Center

One of the vexing problems in controlling breast cancer is the emergence of acquired endocrine-resistance in estrogen receptor positive breast cancers that initially respond to endocrine therapy. Published reports suggest there is a close overlap between the signal transduction pathways affected by 20-hydroxyeicosatetraenoic acid (20-HETE) and those which may confer endocrine-resistance. Preliminary data indicate that 20-HETE-targeted drugs have direct cytotoxic and indirect anti-angiogenic effects on multiple carcinomas, and they therefore might be extended to unsolved problems in breast cancer control. Yet almost nothing is known about the specific role(s) of 20-HETE in either healthy breast tissue or in breast cancer. We observed that treatment of certain tamoxifen-resistant human breast cancer cell lines with HET0016, a compound which inhibits the biosynthesis of 20-HETE, restores sensitivity to tamoxifen in cell culture. We are elucidating the signal transduction pathways involved in this phenomenon. We also observed that certain human breast cancer cell lines with intrinsic tamoxifen resistance (such as the "triple-negative" MDA-MB-468 cell line) express cytochrome P450 isoforms essential for the synthesis of 20-HETE, and we are evaluating whether we can exploit a synergistic effect of HET0016 with anti-cancer drugs currently used to treat aggressive "triple-negative" breast cancers which have an intrinsic resistance to endocrine therapy. We hypothesize that a 20-HETE-targeted agent such as HET0016 will provide an additional anti-cancer benefit due to its anti-angiogenic activities, and we are further exploring the characteristics of breast cancers that may be susceptible to combination therapy involving HET0016 and related compounds.

O2.08

10:45 EFFECTS OF miRNA REGULATION ON [beta]-TUBULIN ISOTYPES

Kevin Morris, Sharon Lobert

University of Mississippi Medical Center

A common active ingredient in chemotherapy drugs, taxane has been shown to have limited effectiveness in treating tumors that are resistant to taxanes after repeated cycles of chemotherapy. Taxanes function by interacting with the [beta]-subunit of the [alpha][beta]-tubulin heterodimer of mircotubules. Using B-tubulin isotypes as tumor biomarkers can create better prognosis for cancer treatments and counteract drug resistance. The Biomarker study done by S. Lobert found that when given a 24-hour 400nM paclitaxel treatment, mRNA of [beta]IIA increases relative to the mRNA of the other [beta]-tubulin isotypes in MCF-7 cells. mRNA of [beta]IIA also remains relatively stable when given a 16-hour actinomycin-D treatment. Due to this, it was hypothesized that there is a down-regulated miRNA that is causing [beta]-tubulin isotypes, ideally BIIA, to remain stable after a 400 nM Taxol treatment. To test this, a series of paclitaxel drugged (experimental and non-drugged control) MCF-7 cells were used to make cDNA after a 24-hour incubation period. MicroArrays of the cDNA samples were then used to compare the regulation levels of the miRNA within the cell, and miRNA assays were performed to validate results obtained from the MicroArrays. As a result, miRNA 100 was found to be down-regulated in the Microarrays and validation assays. The down regulation of this miRNA could be the cause of the stability in the message of BIIA after a 400nM Taxol/actinomycin-D treatment of MCF-7 cells.

O2.09

10:45 SYNTHESIS OF NOVEL PHOTOCLEAVABLE TRANSCRIPTION INITIATORS FOR IN VITRO SELECTION OF RIBOZYMES

Faqing Huang, Yongliang Shi

University of Southern Mississippi

Covalent attachment of chemical functionalities to biomacromolecules

(DNA/RNA/protein) through photocleavable linkers (PC) has broad applications in chemistry and biomedical research. Here we report the synthesis of two novel photocleavable transcription initiators that can be used for the preparation of functionalized RNA for in vitro selection of RNA catalysts. A photocleavable bifunctional O-nitrobenzyl group is introduced into the initiators, flanked on one side by an adenosine and on the other side by either a disulfide bond or a free amino group. Under transcription conditions, the disulfide bond is reduced to generate a free thiol group. To demonstrate their utility, the initiators are used to prepare 5'-thiol and amino-labeled RNAs by in vitro transcription under the T7 [PHI]2.5 promoter. RNA labeling yield can reach 80-90%. Under irradiation of 360 nm photons, photocleavage of both the transcription initiators and the resulting RNA indicates a half-life of 6 min. We are currently using the transcription initiators to isolate new ribozymes that might have played important roles in the RNA world.

O2.10

11:00 REDOX REGULATION OF JAK2 IN PANCREATIC BETA ISLET CELLS

Chetan Patil, Barak Gunter, Roy Duhe

University of Mississippi Medical Center

Oxidative stress is associated with numerous metabolic and degenerative diseases. Our lab has discovered that that two residues (Cys866 and Cys917) act together as a redox sensor switch in the protein-tyrosine kinase JAK2, potentially allowing JAK2's catalytic activity to be directly regulated by the redox state of the cell. This switch may play an important role in the development of type II diabetes, in which beta pancreatic islet cells exhibit impaired functionality after prolonged oxidative stress. JAK2 is an important transducer of insulin-, prolactin- and growth hormone- coupled signals in these cells. In order to show that the redox sensor switch functions under physiological and pathophysiological conditions, we will rescue oxidatively-impaired signal transduction in mammalian cells through the lentiviral expression of a recombinantly-engineered redox-refractive form of JAK2. We have generated lentiviruses expressing V5-tagged rJAK2 and the redox-refractive rJAK2(CC866,917AA), and confirmed their cellular production by immunofluorescence and western blot assays. To ensure that we can experimentally manipulate the intracellular redox environment through growth conditions which approximate physiological parameters, we have performed glutathione assays and flow cytometry measurements using redox-sensitive dyes. We observe that in murine beta pancreatic islet cells that we can manipulate the redox state to become more oxidizing by increasing glucose and oxygen levels. Through these efforts we have established a new cellular model for the study of diseases linked to chronic oxidative stress.

O2.11

11:15 THE ROLE OF ANTI-INFLAMMATION IN PREVENTING REMODELING OF THE HEART CAUSED BY HYPERTENSION

Bindiya Patel, David Murray

University of Mississippi

Hypertension produces an inflammatory response resulting in hypertrophy of the heart. In response to stress, there are cell-cell interactions which promote harmful structural changes in the heart. The hypothesis of this study is that tryptase derived from cardiac mast cells binds to protease activated receptor-2 (PAR-2) on fibroblasts resulting in the increase of expression of cyclo-oxygenase-2 (COX-2). Cyclo-oxygenase-2 causes the production of 15-d-[PGJ.sub.2], which in turn stimulates collagen production. Left ventricular samples were collected and analyzed from 14 day post SHAM operated, pressure overloaded (PO), and PO + Nimesulide treated rats. Expression of COX-2 increased in the PO groups compared to the SHAM groups. Treatment with Nimesulide in the PO groups attenuated COX-2 expression and nearly returned protein levels to SHAM values. Expression of PAR-2 appeared to increase in PO groups and decrease in the PO + Nime treated groups, but these values were not normalized to GADPH due to the short time period allotted for this study. Treatment with the COX-2 inhibitor, Nimesulide, is expected to decrease COX-2 activity and therefore indirectly decrease the concentration of 15-d-[PGJ.sub.2] leading to a decrease in collagen production by fibroblasts.

11:30 ELECTION OF OFFICERS

(Chair and Co-Chair) for serving the Cell, Molecular, and Developmental Biology Division of the MAS in 2012

Biomedical Research: Respiratory Disease and Antibiotic Resistant Mechanisms

O2.13

1:15 ANALYZING THE FUNCTION OF THE MOLD-SPECIFIC GENE M46, IN THE DIMORPHIC FUNGUS HISTOPLASMA CAPSULATUM

Davida Crossley, Glen Shearer

The University of Southern Mississippi

Histoplasma capsulatum is the cause of the respiratory disease histoplasmosis. The dimorphic fungus grows in the soil as a multi cellular mold. Once the soil is disturbed, spores are released and are inhaled into the lungs. For pathogenesis it is a requirement that yeast convert to mold. To understand the molecular basis of dimorphism, we have isolated several mold-specific and yeast-specific genes. The subject of this study is the mold -specific M46 gene. The function of M46 is unknown. According to Genbank, there is an M46 homolog in three fungi. However the function of M46 in these organisms is also unknown. Northern blot analysis has shown that M46 is expressed in G186AS and Downs strains, but is transcriptionally silent in G184AS and G217B strains. The reason for lack of transcription in the latter strains may imply that M46 is not involved in dimorphism. Localization analysis in which M46 was fused to the reporter- Green Fluorescent Protein (GFP) on C- and -N- terminus regions, indicates that M46 is localized to the cytoplasm. Localization to the cytoplasm does not give a clear indication of the function of M46. Recently, an M46 knockout has been constructed. This obvious knock out has shown to have no effect on the yeast phase morphology or growth rate when compared to the morphology and growth rate of wild type. Future work will consist of analyzing the M46 knockout morphology and rate of growth in the mold morphotype and compare to wild type.

O2.14

1:30 OVEREXPRESSION OF GLUTATHIONE BIOSYNTHETIC GENES SUPRESS DIMORPHISM OF THE PATHOGENIC FUNGUS HISTOPLASMA CAPSULATUM

Melissa Adams, Glen Shearer

University of Southern Mississippi

The dimorphic fungus Histoplasma capsulatum is the causative agent of histoplasmosis, a disease that afflicts an estimated 500,000 Americans each year. Histoplasma grows in soil as a saprophytic multicellular mold. In the lungs of an infected host, a shift to the parasitic yeast occurs. The dimorphism from mold to yeast is regulated by many environmental factors such as temperature and thiol concentrations. Sulfhydryl groups (-SH), especially cysteine, are a necessary nutrient for the mold to yeast transition. Glutathione biosynthetic genes, Gamma-glutamyl cysteine synthetase (GSH1) and Glutathione synthetase (GSH2) use cysteine to make the tripeptide glutathione. Northern blot and RT-PCR analysis show GSH1 and GSH2 are weakly expressed in the mold morphotype and strongly upregulated in the yeast morhpotype. Overexpression analysis of GSH1 and GSH2 in the mold morphotype was used to study the role of glutathione synthesis in the dimorphism of histoplasma. Overexpression of GSH1 and GSH2 was driven by the strong Hc Tef1 promoter. The increased expression resulted in yeast cells that were unable to shift to the mold morphotype at 25[degrees]C. Studies are underway to measure glutathione levels as well as GSH1 and GSH2 expression in these transformants.

O2.15

1:45 MSA PLAYS ROLE IN ANTIBIOTIC RESISTANCE AND AUTOLYSIS IN STAPHYLOCOCCUS AUREUS

Gyan. S Sahukhal, Antony Schwartz, Mohamed O. Elasri

The University of Southern Mississippi

Msa is a putative membrane protein with three membrane-spanning regions that are potentially involved in interaction with the environment. We have shown that Msa regulates biofilm formation, antibiotic resistance and virulence. Msa mutant showed increased susceptibilty towards several [beta]-lactams antibiotics. We have found that salt and Polyanethole sulfonate (PAS) affects the msa mutant's biofilm formation. Since salt and PAS have been implicated autolysis, we hypothesize that Msa plays role in this process. Triton-X 100 induced autolysis was triggered at higher rate in Msa mutant relative to wild type. Msa mutant also produced more extracellular DNA than wild type supporting higher rate of autolysis in the mutant. Rate of autolysis was also increased when exposed to sub-inhibitory concentrations of [beta]-lactam antibiotics that were targeted towards penicillin binding proteins. Interestingly, Msa mutant gained resistant to lysostaphin induced autolysis relative to wild type.

O2.16

2:00 CHARACTERIZATION OF DELETION MUTANT OF MSA IN STAPHYLOCOCCUS AUREUS

Maria Basco

University of Southern Mississippi

Antibiotic resistance in Staphylococcus aureus is a growing world-wide issue in public health. S. aureus is resistant to major drugs like methicillin, vancomycin, and oxazolidinones. We have previously described the msa gene as a global regulator controlling biofilm formation and several virulence genes required for MRSA (Methicillin Resistant Staphylococcus Aureus) infections. These observations were made using a transposon-insertion mutant (with Tn551) in S. aureus strains COL, RN6390 and UAMS-1. To verify the role of msa and rule out any polar effects from the transposon, we have created a deletion mutant of msa in COL (MOE334) by allelic replacement; using the temperature sensitive plasmid pKOR1. MOE334 was verified by PCR and sequencing. Effects of the deletion of the msa gene were studied in lipase assay, protease assay, hemolytic assay and biofilm assay. The other effects of the deleted msa gene are still being studied. Future studies with MOE334 in pathological effects (using animal models), its role as a global regulator and in networking with other regulators like sarA and agrA (using RT-qPCR and double mutations) are next in the pipeline. Similar mutations are also being created in other strains like the RN6390 and UAMS-1 to see the role of msa across other strains of S. aureus.

Biomedical Research: Neuroscience

O2.17

2:30 NON-ESTERIFIED FATTY ACIDS (NEFAS) GENERATE DIFFERENT AB42 OLIGOMERS VIA TWO DISTINCT AGGREGATION PATHWAYS.

Rebekah Rice (1), Amit Kumar (1), Pritesh Patel (1), Lea C. Paslay (1), Dipti Singh (1), Ewa A. Bienkiewicz (2), Sarah E. Morgan (1), Vijayaraghavan Rangachari (1)

(1) University of Southern Mississippi, (2) Florida State University

In Alzheimer's disease (AD), soluble oligomers of amyloid-[beta] (A[beta]) are believed to be primary neurotoxic species responsible for early synaptic dysfunction and cognitive decline. The rate of A[beta] aggregation is known to be significantly affected in the presence of anionic interfaces such as lipid, fatty acids & other surfactants. Here, we present the effect of saturated non-esterified fatty acids (NEFAs) on the rate of AP aggregation. We have observed that NEFAs induce more than one pathway of A[beta] aggregation which is dictated by both ratio of A[beta]42 : NEFAs as well as NEFAs respective critical micelle concentrations (CMC). More importantly, we observed that irrespective of their carbon chain lengths, NEFAs generate primarily two types of low molecular weight oligomeric species ; a) near CMC concentration, NEFAs increased the rates of A[beta] aggregation towards fibril formation that generated 12-18mers, and b) at concentration above CMC, NEFAs failed to show any aggregation and generated 4-5mers, while oligomeric 12-18mers seems to adopt 'on pathway' towards fibril formation, the 4-5mers formed via an alternate pathway called 'off-pathway' that did not form fibrils. These oligomers generated were characterized using biophysical techniques like thioflavin-T (ThT) fluorescence, immunoblotting, atomic force microscopy (AFM) and circular dichroism (CD). All these data are presented and discussed.

O2.18

2:45 Isolation and characterization of two distinct Ab42 oligomers generated in the presence of nonesterified fatty acids (NEFAs).

Amit Kumar, Rebekah L. Rice, Lea C. Paslay, Sarah E. Morgan, Vijayaraghavan Rangachari

University of Southern Mississippi

The soluble oligomeric aggregates of amyloid-b (Ab) are the primary toxic species involved in the etiology of Alzheimer's disease (AD). Due to their increased significance in AD pathology, it is important to explore and understand the molecular and structural properties of Ab oligomers. Previously, we have shown that non-esterified fatty acids (NEFAs) affect the rate of Ab aggregation. More importantly, we observed that irrespective of their carbon chain lengths, NEFAs generate primarily two types of low molecular weight oligomeric species ; a) near critical micelle concentration (CMC) concentration, NEFAs increased the rates of Ab aggregation towards fibril formation that generated 12-18mers, and b) at concentration above CMC, NEFAs failed to show any aggregation and generated 4-5mers. The oligomeric 12-18mers seems to adopt 'on pathway' towards fibril formation in contrast the 4-5mers formed via an alternate pathway called 'off-pathway' that did not form fibrils. We now report the detailed charcterization and isolation of these oilgomers. The oligomers generated in the presence of NEFAs were fractionated using size exclusion chromatography (SEC) and peak fractions were characterized using SDS-PAGE, dynamic light scattering (DLS), thioflavin-T (ThT) fluorescence and atomic force microscopy (AFM). The isolated 12-18mers remained stable for a period of 5-6 days and seed the aggregation of Ab. All these data further support our hypothesis of two distinct pathways of Ab aggregation.

O2.19

3:00 COMPETITION EXPERIMENTS SHOW THAT THE [URE3] PRION OF SACCHAROMYCES CEREVISIAE PUTS PRION-CONTAINING CELLS AT A GROWTH DISADVANTAGE

Jeremy Winders, Samantha McCorkle, Katherine

Brinkman, Ross Whitwam

Mississippi University for Women

Prions are infectious proteins which, in mammals are associated with neurodegenerative diseases and have many features in common with non-infectious diseases such as Alzheimer's disease, Parkinson's disease, Huntington's Disease, and others. Yeast prions such as [URE3] serve as model systems for mammalian prions because they share many molecule features in common with them. However, unlike mammalian prions, the yeast prions are not associated with any disease states and while the [URE3] prion has been reported to slow yeast growth, the evidence is not strong. We show that, contrary to published reports, pure cultures of [URE3] yeast grow at exactly the same rates as prion-free yeast in both nutrient-rich and nutrient-limiting media. However, when prion-containing [URE3] yeast are grown in direct competition with prion-free yeast in the same culture, the prion-free yeast outgrow the prion-containing [URE3] yeast and eventually come to dominate the culture. This is the first time the [URE3] prion has been shown to have a deleterious effect on its host and suggests that the [URE3] system may be used to model certain aspects of the disease states of mammalian prions as well as their molecular features.

O2.20

3:15 EFFECT OF SCOPOLAMINE AND SCHIZANDRIN ON SPATIAL LEARNING IN ZEBRA FINCH'S

Diarria Williams, Madeline Coltharp, Brittany

Simpson, Lainy Day

University of Mississippi

The cholinergic system, diminished in Alzheimer's, is important in memory. We tested the effects of scopolamine and the natural product schizandrin on spatial learning in zebra finches. Scopolamine is a drug known to impair spatial learning in mammals but has not been widely tested in birds. However, schizandrin has been found to improve scopolamine induced deficits in spatial memory - specifically in rats. To confirm these findings, we tested the role of both drugs in a spatial learning task. The birds were trained in a spatial escape maze developed in our lab. The subjects were required to escape through a hole 2.5cm above the floor of a Plexiglas cylinder that was sitting on a hot plate. We tested the birds in 5 treatment groups (n=3 per group): low schizandrin (LSZ) (10mg/kg), high schizandrin (HSZ) (20mg/kg), low scopolamine

(LSP) (0.05mg/kg), high scopolamine (HSP)

(3mg/kg), and controls. Path distance, duration, and velocity were recorded using Ethovision (Noldus). Using repeated measures ANOVA, we did not find any significant differences between the treatment groups in duration, distance, or velocity. We did find a marginally significant difference in distance (p>0.09) and in duration (p>0.10) between the HSP and the HSZ group using t-tests to make paired comparisons. We will be performing a follow up experiment to further examine differences between HSZ (20mg/kg), HSP (3mg/kg), and controls.

O2.21

3:30 A GENETIC MODIFIER SCREEN OF MIDLINE IDENTIFIES ENHANCER AND SUPPRESSOR GENE CANDIDATES THAT REGULATE INTEROMMATIDIAL BRISTLE FORMATION IN THE ADULT DROSOPHILA EYE

Deepak Kumar, Sandra Leal

University Of Southern Mississippi

The Drosophila T-box transcription factor midline (mid) regulates cell-fate specification in multiple tissues across diverse species including mammals. However, to date, the complex mechanisms by which mid regulates cell-fate specification are not completely understood. Expression studies between Mid proteins and transcription factors known to specify motor neuron and interneuron fates within the central nervous system (CNS) reveal little co-expression between these factors. Consequently, we are using a classical genetic modifier screen and RNA interference (RNAi) methodology to identify genes that suppress or enhance a dosage-sensitive RNAi bristle phenotype observed in the adult Drosophila eye when midline transcripts are reduced in the eye imaginal discs of third-instar larvae. This high-throughput screening approach facilitates efforts to identify mid-interacting genes that potentially regulate cell-fate specification within the Drosophila eye and within the embryonic central nervous system (CNS). Presently, we have identified several third chromosomal regions harboring enhancer and suppressor candidate genes that regulate interommatidial bristle formation within the adult eye. We are currently assaying mutant alleles of these prospective enhancer/suppressor gene candidates to identify bona fide mid-interacting genes. We then propose to understand how these newly identified genes regulate midline function in the context of both eye and embryonic CNS development. This research will further our understanding of mid function as an integral regulator of cell-fate specification pathways.

Concurrent Afternoon Session

GENOMICS SYMPOSIUM organized by Dr. Sittman (UMMC)

Room 218 A
1.15-1.20 pm:   Opening Remarks

1.20-1.40 pm:   Dr. Phi Do, UMMC

Mutant p53 :    A Multi-Platform Approach to
                Identifying its Role in Cancer and Drug
                Resistance

1.40-2.00 pm:   Dr. Lakshman Varanassi, UMMC
                E2F3 and the DNA damage response: How
                genomics enables discovery

2.20-2.20 pm:   Dr. Shane Burgess and Dr. Fiona
                McCarthy, MSU
                Gene Ontology annotation and modeling

2.20-2.40 pm:   Dr. Shane Burgess and Shyamesh
                Kumar, MSU
                Expression-Proteomics-based systems
                biology modeling in a unique naturally-occurring
                Hodgkin's lymphoma model

2.40-3.00 pm:   Dr. Sukumar Saha, USDA/ARS
                Genomic resources in cotton improvement

3.00-3.20 pm:   Dr. Sarah Buxbaum, JSU/JHS
                Genetics of QT interval duration in the
                Jackson Heart Study

3.20-3.30 pm: Concluding Remarks


February 18,2011

FRIDAY MORNING

9:00-10:30 POSTER SESSION

P2.01

MOLECULAR DETECTION OF TICK-BORNE PATHOGENS IN MIGRATORY BIRDS

William D'Angelo, Michael Sellers, Frank Moore, Shahid Karim

The University of Southern Mississippi

Ticks and tick-borne pathogens can be transported over large distances and across geographical barriers by avian hosts. During the spring migrations of 2009 and 2010, blood samples were collected from 282 passerine birds (30 in 2009, 252 in 2010) at a migration stop-over observatory in Johnson Bayou, Louisiana. Every bird was identified by species and examined for ticks. Ticks found attached to the birds' bodies were removed, identified by species, and stored in individual vials in 70% ethanol. Blood collected from the birds was immediately stored in lysis buffer. Genomic DNA was extracted from the bird blood samples and the ticks using a Qiagen DNA extraction kit. We performed nested polymerase chain reaction using 16S rRNA gene and VLPT gene primers to screen the samples for the bacterium Ehrlichia chaffeensis, an emerging tick-borne pathogen that causes a febrile illness in humans. Evidence of E. chaffeensis infection was found in 15 birds.

P2.02

DETERMINATION OF COPY NUMBER OF HISTOPLASMA CAPSULATUM LIGD (LIG4 HOMOLOG)

Lacey Howard, Glen Shearer

University of Southern Mississippi

Histoplasmosis, the most prevalent cause of respiratory mycoses in humans, is caused by the dimorphic fungus Histoplasma capsulatum (Hc), which can be found in the mold form in micropockets of soils that are heavily fertilized by bird excrement or in the pathogenic yeast form in the lungs of mammals. Hc exists in the mold form at 25[degrees]C and in the yeast form at 37[degrees]C. In order to elucidate the mechanisms that control the mold to yeast phase transition, which is required for pathogenicity, genetic knockout mutants of target genes of Hc are created to study the effect of loss of function of these genes. However, Hc allelic replacement attempts most often result in ectopic insertions, presumably because of non-homologous end joining (NHEJ) repair of DNA. LigD is a DNA ligase that assists in the NHEJ pathway with the assistance of the heterodimer Ku70-Ku80 and the MRX protein. Recent reports in the literature showed that disrupting ligD in Aspergillus oryzae dramatically enhances the efficiency of allelic replacement. We hypothesize that disrupting the ligD homolog in Hc will likewise enhance the efficiency of genetic knockouts in this fungus. To test this hypothesis, we have isolated the Hc ligD homolog (HcligD) from strain G186AS. Sequence analysis indicated this gene encodes a predicted protein of 705 amino acids. Southern blot analysis indicated that HcligD is a single copy gene. Experiments are underway to knockout HcligD in order to study the effects of this loss of function on allelic replacement.

P2.03

THE ROLE OF DNA METHYLATION IN THE PATHOGENIC FUNGUS HISTOPLASMA CAPSULATUM.

Rupesh Patel, Glen Shearer

The University of Southern Mississippi

Histoplasma capsulatum is a dimorphic fungus found as a saprophytic mold in soils contaminated with bird or bat excreta (at 25[degrees]C). When disturbed, the released spores have the potential to be inhaled into the lungs. In the lungs, at 37[degrees]C, the multicellular fungus converts into a unicellular yeast, which is the causative agent for a respiratory infection known as histoplasmosis. Researchers are interested in studying the molecular aspects of the conversion to provide more effective treatment routes. This study is unique because it is a whole-genome based study instead of a single gene study. On going studies in other organisms indicate that DNA methylation plays a crucial role in genetic expression. DNA methylation typically decreases gene transcription; which is essential for normal development and required for the differentiation of cell types. However, there are no previous methylation studies in Histoplasma capsulatum. Hence, the main objective of this project is to assess the role of DNA methylation in Histoplasma capsulatum. To achieve this, genomic DNA was extracted from both the yeast and the mold forms of the Downs strain. Thereafter, the genomic DNA was digested with the isoschizomers HpaII and MspI. As an independent assay of DNA methylation, Histoplasma capsulatum (Downs strain) was grown in the presence of the cytosine analogue, 5-Azacytidine. Furthermore, DNA methylation will be quantitatively analyzed using an enzyme linked immunosorbent assay (ELISA).

P2.04

CHARACTERIZING POPULATIONS OF DOUBLE-STRANDED RNA IN KARENIA BREVIS PRESENT AT DIFFERENT TIMES OF THE DIEL CYCLE

Scott Anglin, Timothy McLean

The University of Southern Mississippi

Karenia brevis is a Auxotrophic, marine dinoflagellate found in the Gulf of Mexico that generates periodic, if not annual, harmful algal blooms (also known as 'red tides') in certain coastal areas. In an effort to better understand the biology of this organism, a functional genomics project has been initiated. As part of that project, it has been determined that a significant number of natural antisense transcripts (NATs) as well as double-stranded RNA (dsRNA) molecules exist within the transcriptome of K. brevis. The purpose of this research is to determine if dsRNAs play a role in regulating gene expression. The methods involved in this procedure include extracting total RNA from cells grown under different culture conditions, isolating and cloning the dsRNAs, and sequencing a representative sample of each clone library. We will assess the relative level of expression of the most abundant genes under the tested conditions. Any differential expression between conditions will support the hypothesis of dsRNAs regulating the expression of genes via a post-transcriptional mechanism. The results of these experiments will possibly lead to a better understanding of environment-gene interactions for this organism, which, in turn, will aid our ability to understand the factors and mechanisms associated with cell growth and bloom formation.

P2.05

A GENETIC MODIFIER SCREEN IDENTIFIES MIDLINE-INTERACTING GENE CANDIDATES IN DROSOPHILA

Jason Wheat, Deepak Kumar, Sandra Leal

University of Southern Mississippi

We are undertaking two comprehensive genetic modifier screens to identify mid-interacting genes to confirm the hypothesis that midline (mid) is an essential member of a novel transcription factor combinatorial code mediating cell-fate specification in the embryonic CNS (Tatum et al., 2010, MAS Research Conference; companion poster). We present the results of the first ongoing genetic modifier screen that assays a dosage-sensitive adult mutant eye phenotype observed when midline transcripts are reduced in the developing third instar larval eye discs of hundreds of chromosomal deficiency lines. Gene candidates identified from this screen will be subjected to a second modifier screen assaying a CNS-specific mutant phenotype. This classic genetic approach will uncover novel midline-interacting genes essential for regulating cell-fate specification in the CNS and developing eye. Preliminary findings are encouraging and have identified a genomic interval harboring mid-interacting genes. These gene candidates also have the potential to regulate the acquisition of normal locomotor adult behaviors (Solomon et al., 2010, MAS Research Conference; companion poster). Current research in the Leal lab is focused on identifying the mid-interacting gene(s) and investigating whether this gene or genes affect the development of neural circuits that support locomotor activity or specific aspects of neurotransmission in third instar larvae and adult fruit flies.

P2.06

THE IDENTIFICATION OF GENES REGULATING MOTOR BEHAVIORS IN DROSOPHILA MELANOGASTER

Melinda Solomon, Katherine Warren, Jason Wheat, Sandra Leal

Oak Groove High School

Neural networks relay electrochemical signals with remarkable speed and accuracy to mediate simple and complex behaviors. The precision of this relay system depends upon the proper development of the central nervous system (CNS) when hundreds upon thousands of diverse neurons are born at "the right time and place" to build circuits. The disruption of neural circuits can result in devastating consequences and severe neurological and neuropsychiatric disorders in humans including epilepsy, schizophrenia, and depression. During a genetic screen to identify genes that are important for regulating neuronal differentiation during early embryogenesis in the fruit fly (Drosophila melanogaster), we uncovered a genomic interval on the third chromosome that harbors one or several genes that affect locomotor behaviors. Specifically, we observe that adult flies that are heterozygous mutant for genes within this genomic interval, exhibit deficits in locomotion, geotactic behaviors and the righting reflex. They also appear to be sensitive to "banging" or being tapped physically on a flat surface. After tapping, the adult flies exhibit a paralytic behavioral phenotype. We are currently examining the development of the embryonic CNS of these heterozygous mutants as well as mutants that completely lack the genomic interval (homozygous mutants) (Wheat et al., MAS Research Conference, 2011; companion poster presentation). Current studies in the Leal lab are identifying the gene or genes within the identified genomic interval that are essential for modulating normal locomotor activities.

P2.07

THE DROSOPHILA INOSINE TRIPHOSPHATASE GENE REGULATES EMBRYONIC CNS DEVELOPMENT

Katherine Warren, Jonathan Buchanon, David Merrill, Sandra Leal

University of Southern Mississippi

Recently, we identified a gene from a chromosomal deficiency screen, Inosine triphosphatase (ITPase) that is essential for regulating the proper formation of the Drosophila nerve cord. Our preliminary studies suggest that ITPase is essential for regulating the morphological integrity, outgrowth and pathfinding behaviors of axons that comprise the longitudinal connectives of the embryonic nerve cord. Deciphering the unique regulatory properties of the ITPase gene in the context of CNS development will reveal new insights into the molecular and genetic nature of axon guidance mechanisms important for the formation of basic neural circuits. Moreover, the fruit fly and human ITPase genes share remarkable structural and functional similarity; a small segment of the human population carries a nucleotide polymorphism for an altered form of the ITPase (P32T mutation). These individuals poorly tolerate azothioprine treatment, a purine analog and commonly prescribed immunosuppressive drug. As such, we administered azothioprine systemically to wild-type and ITPase heterozygous mutant adult flies to determine if we could phenocopy the toxicity observed in human patients. We monitored adult survival rates and basic locomotor behaviors as indicative measures of toxicity. However, we did not observe any lethal effects. We are currently assessing whether fruit fly mutant larvae are more sensitive to azothioprine treatment and also devising a genetic approach to create ITPase CNS-specific conditional knockouts via an RNAi approach and the UAS-Gal4 binary expression system. These conditional knockouts will confirm that the ITPase is required for supporting normal neuronal function within post-embryonic stages of Drosophila development.

P2.08

AN UNBIASED GENETIC MODIFIER SCREEN IDENTIFYING MIDLINE-INTERACTING GENES IN DROSOPHILA

April Tatum, Deepak Kumar, Jason Wheat, Samuel Muller, Andrew Meriwether, Sandra Leal

University of Southern Mississippi

The central nervous system (CNS) of Drosophila melanogastor is comprised of hundreds of diverse neurons. Presently, the genes that specify the fates of these differentiated post-mitotic neurons have not yet been completely identified. However, studies in Drosophila and vertebrate systems have revealed that conserved sets of transcription factor genes specify the identities of different classes of motor neurons and these precise observations led to the postulation of the combinatorial code model for neuronal specification. To decipher transcription factor codes that specify neuronal identities, a chromosomal deficiency screen was undertaken to find genes that modify the expression of even-skipped (eve), a transcription factor gene and well characterized determinant of CNS neuronal fates. From this screen, the T-box transcription factor midline (mid) was identified as a new combinatorial transcription factor code member (Leal et al., 2009). We are currently undertaking two comprehensive genetic modifier screens to identify mid-interacting genes to confirm the hypothesis that mid is an essential member of a novel transcription factor combinatorial code mediating cell-fate specification in the embryonic CNS. The first genetic modifier screen assaying a dosage-sensitive mutant eye phenotype observed when mid transcripts are reduced in the developing eye of hundreds of heterozygous chromosomal deficiency mutant fly lines is providing encouraging results and potential mid-interacting genes. These gene candidates will then be assayed via a second modifier screen to determine whether they regulate cell-fate specification within the embryonic CNS.

P2.09

MECHANICAL AND CHEMICAL STIMULATION OF THE VAGAL AFFERENT NERVES REGULATING COUGH

Chioma Udemgba, Jackie Smith, Yang-ling Chou, Brendan Canning

The Johns Hopkins Asthma and Allergy Center, Bayview Campus

The cough reflex is a vital reflex mechanism necessary for keeping the respiratory system safe from aspirate. In both humans and animals, this reflex can be evoked by various mechanical and chemical stimuli. In order to develop more effective treatments for cough, additional information must be known about how this reflex is initiated in the airways and about the neurological pathways by which it is induced. This project targeted the vagal afferent nerves that regulate the cough reflex innervating the trachea of anesthetized guinea pigs. Attempts at evoking cough were carried out in guinea pigs by subjecting them to various mechanical stimuli and by applying citric acid topically to the tracheal mucosa (used routinely in clinical studies of the cough reflex). Although cough was routinely observed during surgical preparation of the airways and in response to mechanical probing of the mucosa, none of the mechanical stimuli studied here reliably evoked coughing. By contrast, citric acid evoked coughing upon topical application to the tracheal mucosa and was shown to be substantially reduced by topical pretreatment with FK506, an inhibitor of the phosphatase, calcineurin. From these results we conclude that particulate and acidic aspirate is likely initiators of cough whereas airways obstruction is unlikely to cause coughing. The results also suggest that a regulator of cough receptor excitability, perhaps the alpha3 subunit of the Na+-K+-ATPase (Bertorello et al., Proc Natl Acad Sci U S A. 1991; 88(24):11359-62; Mazzone et al., J Neurosci. 2009; 29(43):13662-71), may be negatively regulated by phosphorylation.

P2.10

[beta]-TUBULIN CLASSES II AND III ARE DIFFERENTIALLY REGULATED IN MCF7 BREAST CANCER CELLS

Sharon Lobert, Bianca Jefferson, J. Graham Hudson, Kevin Morris

University of Mississippi Medical Center

The effectiveness of taxanes for the treatment of solid tumors is reduced because some tumors are initially resistant or become resistant to taxanes after repeated cycles of chemotherapy. Taxanes interact with p-subunit of the [alpha][beta]-tubulin heterodimer and stabilize microtubules of mitotic spindles. It has been proposed that changes in amounts of [beta]-tubulin isotypes or microtubule interacting proteins could contribute to drug resistance. We investigated changes in [beta]-tubulin isotypes and MIPs in response to paclitaxel in MCF7 and MDA-MB-231 breast cancer cells. We chose these cell lines because MCF7 cells are known to express wild type tumor suppressor p53, whereas MDA-MB-231 cells express a mutated inactive form. We demonstrated previously that these two cell lines express primarily [beta]-tubulin classes I, IV and V (Hiser et al., 2006, Cell Motil Cytoskel, 63:41-52). Because MCF7 cells express wild-type tumor suppressor protein p53, we performed siRNA experiments to reduce p53 protein levels and test for changes in [beta]-tubulin class III levels. We found that p53 protein and [beta]-III tubulin levels increase with paclitaxel treatment. When p53 levels are reduced or absent, [beta]-tubulin class III protein is also reduced. We conclude that regulation of [beta]-III tubulin is, in part, determined by active p53 in MCF7 cells.

P2.11

THE EFFECT OF MODELED MICROGRAVITY ON MACROPHAGE GENE EXPRESSION

Demitrius Boyson, Jasmine Washington, Ming Shenwu, Jinghe Mao

Tougaloo College

The effects of spaceflight on the infectious disease process have been studied at the level of the host immune response and indicate a blunting of immune mechanism. However, it is not clear whether exposure to space environment will alter the genetic and physiological properties of immune cells. The increased risk of muscular atrophy, bone demineralization or cancers may result from immune dysfunction caused by the interaction of space flight factors (e.g., radiation, microgravity, stress, isolation, extreme environments et al.). The risk may be influenced by immune dysfunction, latent viral infections, or host genetics. In particular, latent viruses (e.g., Epstein-Barr virus, herpes simplex, polyomaviruses, and hepatitis viruses) can become active and potentially initiate tumor formation. To better understand the effect of microgravity on macrophage inflammatory response, [RT.sup.2] Profiler[TM] PCR Array has been employed to profile the expression of 84 key genes involved in inflammatory cytokines & receptors of the RAW 264.7 murine macrophage cell line. Our results revealed changes in the expression of several genes including Ccl12 (3.2 fold), Cd40lg (2.2 fold), Ccr2 (-7.7 fold), Il6ra (-2.2 fold) and Ltb (-3.7 fold) in macrophages grown under modeled microgravity (MMG) for 48 hours using high-aspect-ratio rotating-wall vessel bioreactor (HARV). Our results indicated that the macrophage gene expression profile was altered by microgravity; especially down-regulation of genes essential in skeletal muscle regeneration (Ccr2), up-regulation of genes necessary for initiating the atherosclerosis (Cd40lg) and genes mediating immunosuppression in tumors (CCL2).

P2.12

IDENTIFICATION OF GENES DIFFERENTIALLY EXPRESSED IN ELONGATING FIBER IN A COTTON CHROMOSOME SUBSTITUTION LINE CS-B25

Samuel Bandi, Din-Pow Ma

Mississippi State University

Recently 17 interspecific chromosome substitution lines (CS-B lines) of upland cotton in G. hirsutum TM-1 background containing whole chromosomes or chromosome arms of G. barbadense (line 3-79) chromosomes have been developed and released to the public. These lines are genetically identical except that each differs by the replacement of a specific homologous pair of chromosomes from 3-79 (G. barbadense) into the Upland background. The 17 CS-B lines carry alleles with positive effects on fiber traits and some with negative effects. The CS-B25 line, which has chromosome 25 from G. barbadense substituted into TM-1, exhibits fiber with increased fiber length, strength, and lower micronaire which are all positive traits for fiber quality. Additionally CS-B25 yields are similar to TM-1. These results form a solid base that allows us to compare gene expression between CS-B25 and TM-1 lines during different stages of fiber development. In this study Affymetrix cotton genome arrays and subtraction hybridization have been used to identify up- and down-regulated genes in elongating fiber in CS-B25 in comparison to TM-1. This approach will ultimately allow us to identify cotton genes on the chromosome 25 of G. barbadense 3-79 which are associated with fiber quality traits.

P2.13

EXPRESSION OF Trametes elegans WOOD DECAY ENZYMES ON DIFFERENT DURABLE WOODS DURING DECAY IN FOREST SOIL

Min Lee (1), Young-Min Kang (2), Lynn Prewitt (1) (1) Mississippi State University, (2) USDA-ARS, Genetic Research Unit, Cornell University

The understanding of microbial decay processes on wood in a forest soil is an important issue for maintaining healthy forest systems. The primary biotic wood decomposers are white rot and brown rot fungi called basidiomycete which degrade all wood components (cellulose, hemicellulose, and lignin) in order to obtain food sources. A common white rot fungi, Trametes elegans, was identified and detected on different durable woods (pine, cedar, and ACQ-treated pine) during a 26 month soil bed decay test. The objective of this study was to determine gene expression of wood decay enzymes lignin peroxidase (Lip), manganese peroxidase (Mnp), and laccase (Lcc) in T. elegans on pine (decay nonresistant wood), cedar (naturally decay resistant), and alkaline copper quaternary (ACQ) treated pine (chemically treated decay resistant). Total RNA was extracted from wood samples at 0, 4, 10, 18, and 26 months of decay, and then converted to cDNA. Real-time PCR was used to quantitate gene expression levels of Lip, Mnp, and Lcc genes of T. elegans. Basidiomycete specific 18s rRNA gene was used as an internal gene and detected on all wood samples. At 10 and 18 months, only Mnp was detected on all wood types. The Mnp expression level was higher on cedar than pine and ACQ-treated pine. Lip was present only on ACQ-treated pine, and Lcc was not detected on any of the woods. At this time, results indicate that the woods of different durability influence the type and amount of wood decay enzymes produced during decay.

11:15-11:45 Awards Ceremony for Best Oral Presentations and Best Poster Presentations

FRIDAY AFTERNOON

Room 216

1:15-3:40 Infectious Diseases Symposium
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Publication:Journal of the Mississippi Academy of Sciences
Geographic Code:1USA
Date:Jan 1, 2011
Words:8427
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