@article{oai:repo.qst.go.jp:00044982,
 author = {Ishii, Nobuyoshi and Sakashita, Tetsuya and Takeda, Hiroshi and Kubota, Yoshihisa and Fuma, Shoichi and Doi, Masahiro and Takahashi, Sentaro and 石井 伸昌 and 坂下 哲哉 and 武田 洋 and 久保田 善久 and 府馬 正一 and 土居 雅広 and 高橋 千太郎},
 issue = {2/3},
 journal = {Journal of Environmental Radioactivity},
 month = {Jun},
 note = {Extracellular DNA is omnipresent in aquatic environments and is thought to be a genetic material for horizontal gene transformation between microorganisms.  We studied the impact of gamma irradiation on the transformation efficiency (transformants number per ng of DNA per ml) of extracellular DNA.  Plasmid pEGFP as a model extracellular DNA was irradiated by gamma rays.  The transformation efficiency decreased with the increase in radiation dose.  A total dose of 10 Gy is normally not lethal for microorganisms but certainly affects the transformation efficiency of extracellular DNA.  The decrease in the efficiency would be induced by strand breaks of extracellular DNA because the yield of both single- (SSBs) and double- strand breaks (DSBs) increased with the increase in radiation dose.  The relative transformation efficiency of SSBs and DSBs to that of covalently closed circles (CCCs) was 30.3% and 0.2%, respectively.  This impact on natural transformation suggests an inability of microorganisms to acquire new characteristics which should be normally acquired.},
 pages = {159--167},
 title = {Impact of gamma irradiation on the transformation efficiency for extracellular plasmid DNA},
 volume = {97},
 year = {2007}
}