@misc{oai:repo.qst.go.jp:00069019,
 author = {Shiomi, Naoko and Noshiro, Katsuko and Kito, Seiji and Masumura, Kenichi and Nohmi, Takehiko and Shiomi, Tadahiro and 塩見 尚子 and 野代 勝子 and 鬼頭 靖司 and 増村 健一 and 能美 健彦 and 塩見 忠博},
 month = {Jul},
 note = {We have carried out mutation assays in germ cells from the transgenic mice after irradiation of various doses of ionizing radiation at the post-meiotic spermatid stage, to learn the difference in sensitivity to ionizing radiation in mutation induction among somatic cells and male germ cells (pre-meiotic spermatogonial stem cell and post-meiotic spermatid stage). The transgenic mice used for the assay are the gpt-delta mouse strain, which carries about 80 copies of the bacterial gpt gene per cell as targets for mutagenesis. To measure the induced mutation frequencies in male germ cells (spermatid stage), sperms were extracted at the 14th day after irradiation of 2.5 or 5 Gy of X rays, corresponding to the spermatid stage at the time of treatment. The spontaneous gpt gene mutation frequency in male germ cells was 0.36 x 10-5. The mutation frequencies in male germ cells irradiated with 2.5 or 5 Gy of X rays at the spermatid stage were 0.60 or 1.03 x 10-5, respectively. The induced mutation frequencies in male germ cells irradiated at the spermatid stage were nearly the same as those irradiated at the spermatogonial stem cell stage (0.53 or 1.05 x 10-5 for 2.5 or 5 Gy of X-ray-treatment, respectively), and about three to four times lower than those in somatic cells (2.43 or 3.46 x 10-5 for 2.5 or 5 Gy of X-ray-treatment, respectively). This difference between somatic and male germ cells in the mutation frequency would be mainly due to the high base excision repair activity in male germ cells., The 13th International Congress of Radiation Research},
 title = {Comparative studies on spontaneous and ionizing radiation induced mutagenesis between somatic and male germ cells},
 year = {2007}
}