title: Responses of embryonic germ cells of the radiation-sensitive Medaka mutant to gamma-irradiation.
abstract: The radiation-sensitive mutant "ric1" has a defect in the repair mechanism of DNA double strand breaks induced by gamma-rays in early embryogenesis. In this study, the new radiation-sensitive Medaka (Oryzias latipes) strain, ric1olvas-GFP was established to monitor the development of germ cells in vivo. The development of germ cells was normal in ric1olvas-GFP, but embryonic germ cells at Stage 7 (32-cell stage) and Stage 33 (extensive proliferating stage of PGCs) showed higher radiosensitivity. There was no sex difference in germ cell radiosensitivity at Stage 7, but female embryos showed higher radiosensitivity than male at Stage 33. In embryos obtained by crossing ric1 female with olvas-GFP male, germ cells showed similar radiosensitivity to ric1olvas-GFP and increased sensitivity compared to embryos obtained from crossing wild-type female with olvas-GFP male at Stage 7. These results suggest that germ cells have the ric1 dependent DNA repair system during embryogenesis and the maternal ric1gene factor may play a critical role in radiosensitivity at an early developmental stage.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Japan.
authors.forename: Kouichi
authors.initials: K
authors.lastname: Aizawa
authors.forename: Kanako
authors.initials: K
authors.lastname: Yori
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kaminaga
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yamashita
authors.forename: Masato
authors.initials: M
authors.lastname: Kinoshita
authors.forename: Shoji
authors.initials: S
authors.lastname: Oda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mitani
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D004260:DNA Repair / Q000528:radiation effects*; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000528:radiation effects*; D005260:Female; D005720:Gamma Rays; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D018895:Microsatellite Repeats; D009154:Mutation; D009990:Oryzias; D012737:Sex Factors; D013997:Time Factors; D019076:Transgenes
chemical_list: D049452:Green Fluorescent Proteins