Dichotomous relationship between DNA reactivity and the induction of sister chromatid exchanges in vivo and in vitro.

Structural analyses of the determinants associated with the induction of bone marrow sister chromatid exchanges in mice indicate that the phenomenon is based on an electrophilic attack on DNA. In that respect this phenomenon is different from the basis of the induction of SCE in cultured cells or of micronuclei in the bone marrow of rodents. The latter two phenomena involve other targets as well. Based on the recognition that the vast majority of recognized human carcinogens are genotoxic, the present finding indicates that the in vivo induction of SCE is a good biomarker, possibly even a biodosimeter, for exposure to potential carcinogens.