Mutagenic effect of carbon ion beams in

Sato, Katsuya; Onodera, Takefumi*; Takeda, Kiyoko; Narumi, Issey*

In this study, we investigated mutant frequencies of two different antibiotic-resistant mutants for carbon ion beams in and identified the mutation sites in the streptomycin-resistant (Sm) mutants. The Sm mutant frequencies increased depending on radiation dose. It seems that this dose range is the best dose to generate the mutants of interest for research and breeding purpose. Four kinds of mutation sites at the locus were determined from 8 Sm mutants. These mutations cause amino acid substitutions at position 43 (Lys to Thr or Arg) and 88 (Lys to Glu or Arg) in the S12 protein, respectively. The two hot spots at Lys43 and Lys88 in the S12 protein might be a binding target of streptomycin or adjacent to the center of streptomycin interaction with the ribosome.