Molecular characterization of 125I decay and X-ray-induced HPRT mutants in CHO cells.

The predominant initial lesion induced by 125I decay in DNa is a double-strand DNA break comprising a 'mini deletion' of up to several base pairs (bp). However, Southern analysis of the structure of 125I decay-induced HPRT mutants in Chinese hamster ovary cells revealed that most of the mutants are deletions of thousands of bps. A similar predominance of substantial deletions was also found in X-ray-induced mutants.