title: A threshold exists in the dose-response relationship for somatic mutation frequency induced by X irradiation of Drosophila.
abstract: The dose-response relationship of ionizing radiation and its stochastic effects has been thought to be linear without any thresholds. The basic data for this model were obtained from mutational assays in the male germ cells of the fruit fly Drosophila melanogaster. However, it is more appropriate to examine carcinogenic activity in somatic cells than in germ cells. Here the dose-response relationship of X irradiation and somatic mutation was examined in Drosophila. A threshold at approximately 1 Gy was observed in DNA repair-proficient flies. In the repair-deficient siblings, the threshold was smaller and the inclination of the dose-response curve was much steeper. These results suggest that the dose-response relationship between X irradiation and somatic mutation has a threshold and that the DNA repair function contributes to its formation.
authors.affiliation: Environmental Biotechnology Laboratory, Railway Technical Research Institute, Tokyo 185-8540, Japan. koana@criepi.denken.or.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Koana
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takashima
authors.forename: Mikie O
authors.initials: MO
authors.lastname: Okada
authors.forename: Masateru
authors.initials: M
authors.lastname: Ikehata
authors.forename: Junji
authors.initials: J
authors.lastname: Miyakoshi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakai
mesh_terms: D000818:Animals; D003433:Crosses, Genetic; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D004331:Drosophila melanogaster; D005260:Female; D005838:Genotype; D006801:Humans; D019656:Loss of Heterozygosity; D016296:Mutagenesis; D009152:Mutagenicity Tests; D009154:Mutation; D011839:Radiation, Ionizing; D014921:Wings, Animal / Q000528:radiation effects; D014965:X-Rays
chemical_list: D004247:DNA