Saturday's sessions--Section IX: Genetics Society of Georgia

Georgia Journal of Science, 2002

252 Herty Hall Brice D. Ostrow, presiding

8:00 The PLASMODIUM FALCIPARUM PEBL PROTEIN AND PLASMODIUM REICHENOWI HOMOLOGUE, A RECENT EVOLUTIONARY DIVERGENCE, Michael Dillard2*, Julian Rayner2 and John W Barnwell2, 1Kennesaw State University, Kennesaw, GA and 2NCID, CDC, Chamblee, GA 30341. DNA 1.SkB fragments towards the 5' end of the Plasmodium reichenowi PEBL gene were amplified using the primers 5-gatGTGGTTTATGTACATAC-3 and 5catATAATGCATTATTCTCAATC-3 utilizing High Fidelity PCR (Roche). The DNA fragments were restricted, purified, and subcloned into the pCR Script Amp SK( ) cloning vector (Stratagene). A BigDye Terminator Cycle Sequencing v2.0 Ready Reaction Kit (ABI Prism) was used to sequence P reichenow PEBL DNA on a 3100 Genetic Analyzer (ABI Prism). P reichenowi PEBL gene sequence was analyzed and compared to P falciparum PEBL using MacVector 6.5 DNA/Protein analysis software (Oxford Molecular).

8:15 TRANSCRIPTION-COUPLED REPAIR OF UV-INDUCED DAMAGE IN THE EXTREMELY HALOPHILIC ARCHAEON, HALOBACTERIUM SP NRC-1, Jarrod E. Dumpe* and David J. Crowley, Mercer University, Macon, GA 31207. Exposure of cells to ultraviolet light (UV) results in damage to their genome, mutations, and cell death. Nucleotide excision repair (NER) occurs in the Bacteria and Eukarya and is responsible for repair of UV damage as well as other DNA lesions. Transcription-coupled repair (TCR) is a sub-pathway of NER that results in faster repair of lesions in the template strand of an actively transcribed gene. TCR occurs in several bacterial and eukaryotic species and we seek to determine whether it occurs in the Archaea, an evolutionarily distinct domain of prokaryotes. We use the halphilic archaeon Halobacterium NRC-1 to measure the rate of repair of UV-induced damage in the two strands of the rpoB'B"AC operon. We are quantifying repair of the induced damage over time through the use of fluorescent strand-specific RNA probes and an imaging system. Preliminary results indicate that repair of pyrimidine dimers does occur in Halobacterium. Evidence of an increased rate of repair in the transcribed strand of the rpoB'B"AC operon would be the first documented evidence of TCR in the Archaea. This result would imply that the Archaea employ a unique mechanism for TCR in which a eukaryotic-like RNA polymerase is coupled to bacterial NER homologs to complete the process.

8:30 ROLE OF THE RAD51/recA HOMOLOG radA IN UV-INDUCIBLE RESPONSES IN THE HALOPHILIC ARCHAEON, HALOFERAX VOLCANII, Lucy E. Davis* and David J. Crowley, Mercer University, Macon, GA 31207. Exposure of cells to ultraviolet light (UV) results in DNA damage, induction of mutations, and cell death. While research on DNA repair has been conducted with species ranging from bacteria to humans, little is known about these processes in the volutionarily distinct domain of prokaryotes called the Archaea. In Escherichia coli, the RecA gene is UV-inducible and required for the induction of the SOS response. Non-lethal doses of UV induce recA, activating SOS-regulated repair proteins that provide an enhanced UV-resistance when the cells are challenged with subsequent lethal doses. We study the extremely halophilic archaeon, Haloferax volanii, known to possess the ability to repair UV-induced DNA damage. We use the wild type strain WFD 11 and its derivative, DS52, which lacks the radA gene, an archaeal member of the recA/RAD51 family of recombinases. We are investigating the response of radA to UV treatment and its role, if any, in regulating cellular responses to UV. We predict that pre-irradiated WFD 11 cells will show an enhanced UV-resistance compared to DS52 cells receiving the same treatment. This result would demonstrate a role for radA in the UV-tolerance and repair systems of H. volcanii.

8:45 ISOLATION AND GENETIC ANALYSES OF COPPER UTILIZATION MUTANTS OF SACCHAROMYCES CEREVISIAE, Joshua A. Fields* and Brian W Schwartz, Columbus State University, Columbus, GA 31907. Although copper is essential as a trace element in yeast and other organisms, it is toxic in high concentrations. Therefore, elaborate mechanisms for establishing and maintaining copper homeostasis have evolved. Several mutants defective in copper transport, distribution, and detoxification have been identified, demonstrating the utility of yeast as a model system for studies of copper homeostasis. To further characterize genetic mechanisms of copper homeostasis in yeast, we have isolated five new mutants that show various abnormalities when grown in the presence of copper. Four mutants develop abnormal colors ranging from tan to dark brown and are slightly to moderately sensitive to copper. Another mutant shows not growth at all in the presence of 1 mM copper. We are currently carrying out genetic crosses to determine modes of inheritance and allelic relationships among the new mutants. We are also further characterizing their phenotypes by growing the mutants in the presence of various concentrations of copper and other metals.