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Spaceflight Effects on Genetics of Streptomyces lividans 66.     B.H. Pyle1, T. A. Voeikova2, V.Y. Tabakov2. 1Microbiology Dept., Montana State Univ. (MSU), Bozeman, MT, and 2Inst. of Genetics & Selection of Industrial Organisms (GosNIIGenetika), Moscow, Russia.

   Streptomyces lividans is a Gram-positive species of actinobacteria that forms a hyphal mycelium and differentiates into spores. These microbes are susceptible to genetic recombination and can be used for in vivo genetic analysis by plasmid-mediated conjugation and protoplast fusion. S. lividans 66 harboring plasmid pIJ702 was selected to study spaceflight effects including radiation and microgravity on structural stability and genetic transfer. The plasmid includes genes for melanin production and thiostrepton resistance which are used as markers for genetic stability, mutation, or transfer. Cultures were spread on modified ISP agar medium with or without thiostrepton either as a low inoculum (10-30 colonies/plate) or high inoculum (confluent growth). Plates were flown with radiation and temperature monitors on Foton-M2 (May 31-June 16, 2005). Spores or mycelium are harvested and frozen for later analysis. At GosNIIGenetika, restriction fragment polymorphism (RFLP) is being used to demonstrate plasmid DNA strain differences generated by flight vs ground controls. MSU is using polymerase chain reaction (PCR) coupled with denaturing gradient gel electrophoresis (DGGE) and gene sequencing to detect point mutations in plasmid DNA extracts and amplicons. Results from these techniques indicate genetic differences between strains in relation to expression of the thiostrepton and melanin genes, as well as other changes that may be identified by sequence analysis. This experiment will lead to insights into potential effects of spaceflight on genetic stability in bacteria and higher organisms, which will be a significant factor in future long-duration spaceflight missions, including those carrying crews to the Moon and on to Mars.

(Supported by the Institute for Biomedical Problems, Moscow, Russia, and NASA: NCC2-1143.)