PERSISTENCE OF CHROMOSOMAL LESIONS INDUCED IN MOUSE BONE-MARROW CELLSBY MITOMYCIN-C, AS EVALUATED BY SCE ANALYSIS

The frequency of sister-chromatid exchanges (SCE) was evaluated in mou se bone marrow cells at different time intervals (from 19 h to 10 days ) after treatment i.p. with mitomycin C (MMC; 1 and 2 mg/kg body weigh t). Significantly higher frequencies of SCE were found during the firs t week after treatment, at both doses tested. This result confirms tha t chromosomal lesions induced by MMC in the mouse may persist in bone marrow cells, in agreement with previous evidence based on chromosomal aberration analysis in the same cell population. In addition, the obs ervation of a unimodal distribution of SCE/cell frequencies at each ti me tested indicates that the bone marrow cell population on the whole is affected by increased SCE frequency, i.e., that persistent chromoso mal lesions may be transmitted along with cell proliferation.