A U-shaped dose-response relationship between x radiation and sex-linked recessive lethal mutation in male germ cells of Drosophila.
We reported previously that low-dose X irradiation of DNA repair-proficient immature sperm of wild-type Drosophila melanogaster at a low dose rate (50 mGy/min) resulted in a mutation frequency that was lower than that in the sham-irradiated group. Therefore, a U-shaped dose-response relationship was suggested. Here we show that the dose-response curve is actually U-shaped by carrying out a large-scale sex-linked recessive lethal assay using Drosophila. No reduction of the mutation frequency was observed in a strain mutant for the nucleotide excision repair gene mei-9a (Drosophila homologue of human XPF). Introduction of a chromosome fragment containing mei-9+ into the mei-9a mutant strain restored the reduction of the mutation frequency in the low-dose-irradiated group. These results showed that DNA repair was responsible for the U-shaped dose-response relationship in Drosophila.
Koana
Takao
T
Radiation Safety Research Center, Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan. koana@criepi.denken.or.jp
Tsujimura
Hidenobu
H
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004331:Drosophila melanogaster / Q000235:genetics* / Q000528:radiation effects; D005260:Female; D005804:Genes, Lethal; D005808:Genes, Recessive; D020287:In Situ Nick-End Labeling; D008297:Male; D009154:Mutation; D013094:Spermatozoa / Q000528:radiation effects*