title: Radiation dose-rate effect on mutation induction in spleen and liver of gpt delta mice.
abstract: The effect of dose rate on radiation-induced mutations in two somatic tissues, the spleen and liver, was examined in transgenic gpt delta mice. These mice can be used for the detection of deletion-type mutations, and these are the major type of mutation induced by radiation. The dose rates examined were 920 mGy/min, 1 mGy/min and 12.5 microGy/min. In both tissues, the number of mutations increased with increasing dose at each of the three dose rates examined. The mutation induction rate was dependent on the dose rate. The mutation induction rate was higher in the spleen than in the liver at the medium dose rate but was similar in the two tissues at the high and low dose rates. The mutation induction rate in the liver did not show much change between the medium and low dose rates. Analysis of the molecular nature of the mutations indicated that 2- to 1,000-bp deletion mutations were specifically induced by radiation in both tissues after high- and low-dose-rate irradiation. The occurrence of deletion mutation without any sequence homology at the break point was elevated in spleen after high-dose-rate irradiation. The results indicate that the mutagenic effects of radiation in somatic tissues are dependent on dose rate and that there is some variability between tissues.
authors.affiliation: Department of Cell Biology, Graduate School of Medicine, Tohoku University, Sendai 980-8575, Japan.
authors.forename: Naohito
authors.initials: N
authors.lastname: Okudaira
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Uehara
authors.forename: Kazuo
authors.initials: K
authors.lastname: Fujikawa
authors.forename: Nao
authors.initials: N
authors.lastname: Kagawa
authors.forename: Akira
authors.initials: A
authors.lastname: Ootsuyama
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Norimura
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Saeki
authors.forename: Takehiko
authors.initials: T
authors.lastname: Nohmi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Masumura
authors.forename: Tsuneya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Oghiso
authors.forename: Kimio
authors.initials: K
authors.lastname: Tanaka
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ichinohe
authors.forename: Shingo
authors.initials: S
authors.lastname: Nakamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tanaka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ono
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D029968:Escherichia coli Proteins / Q000235:genetics*; D008099:Liver / Q000378:metabolism / Q000528:radiation effects*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010430:Pentosyltransferases / Q000235:genetics*; D013154:Spleen / Q000378:metabolism / Q000528:radiation effects*
chemical_list: D029968:Escherichia coli Proteins; D004247:DNA; D010430:Pentosyltransferases; C071962:Gpt protein, E coli