The effects of msh2 or p53 deficiency on spontaneous and radiation-induced mutation rates in the medaka germline.

Abstract

Radiation is a well-characterized carcinogen and mutagen. Radiation has also recently been shown to increase the frequency of mutations at tandem repeat loci. Microsatellite (Ms) DNA loci are short tandem arrays of simple DNA sequences with core repeat units of 1 - 6 bp. Mutation rates at 30 expanded Ms loci were studied in the germ line of mismatch repair deficient msh2 or p53 deficient medaka. Spontaneous mutation rate in homozygous msh2 males were significantly higher than those in isogenic wild-type or p53 deficient fish. In contrast, the irradiated msh2 fish did not show any additional increases in their mutation rate compared to wild-type fish, whereas significant increase in mutation induction was observed in the irradiated p53 fish.