DNA sequence determination of gamma-radiation-induced mutations of the hamster aprt locus.

From a collection of 85 independent gamma-radiation hamster aprt- mutants, 27 having no major structural alterations were analysed at the nucleotide level by using the polymerase chain reaction to amplify mutant exons and then directly sequencing the double-stranded products. The majority of these mutations were simple base substitutions of all types, particularly transversions (11/27). Frameshifts and small deletions were also induced. The 'spectrum' of mutations produced by gamma-radiation was not significantly different from that occurring spontaneously at this locus. Differences with respect to the target and structure of frameshifts and small deletions occurring in the two collections were apparent.