Aging and sister chromatid exchange. V. The effect of post-embryonic development on mutagen-induced sister chromatid exchanges in mouse and rat bone marrow cells.

Induction of sister chromatid exchanges (SCE) was examined as a function of post-embryonic development in C57BL/6J mice and Wistar rat bone marrow cells. At low concentrations of three different mutagens, cyclophosphamide, mitomycin C, and doxorubicin, induced SCE levels were not altered with post-embryonic development. However, at higher mutagen concentrations, SCE induction was significantly reduced in growing (3- to 8-week-old) animals when compared to mature (7- to 9-month-old) animals. Studies of 1- to 8-month-old mice at these high doses revealed that mutagen-induced SCE frequencies increase gradually during this period. These results suggest that with post-embryonic development, changes occur in cellular response to mutagen-induced DNA damage.