Identification of Types of Mutations Induced by Biologically-Produced Oxygen Free Radicals.
Final rept. 1 Nov 74-31 Oct 76,
DUKE UNIV DURHAM N C DEPT OF MICROBIOLOGY AND IMMUNOLOGY
Pagination or Media Count:
A number of strains of Salmonella typhimurium were used to demonstrate endogenous mutagenesis by biologically-produced oxygen free radicals. Cells which are grown anaerobically, and therefore which possess low levels of superoxide dismutase are killed when exposed to oxygen in the presence of an oxidizable carbon source and puromycin. Aerobically-grown cells which contain high levels of superoxide dismutase survive identical treatment. A number of indicator strains were used to show that exposure of anaerobically-grown cells to oxygen caused deletions, frameshift and apparent base substitution mutations. It also was shown that a recA- mutant strain of S, typhimurium is more sensitive than is the wild type strain to oxygen exposure, but does not yield mutants, which shows that under the conditions described, direct damage to DNA is the cause of the enhanced mutation frequency.