CYTOGENETIC EFFECTS OF BENZIMIDAZOLES IN MOUSE BONE-MARROW

The cytogenetic effects of three benzimidazoles, i.e., benomyl, methyl thiophanate and methyl 2-benzimidazolecarbamate (MBC), were studied i n mouse bone marrow cells by analyzing three genetic endpoints: micron uclei, structural chromosome aberrations plus or minus gaps, and aneug enic effects (hyperdiploidy or polyploidy). In general, the effects we re small, but it was observed that benomyl and MBC significantly induc ed micronuclei as well as aneugenic effects, hyperdiploidy (no metapha ses with more than one or two extra chromosomes, 2n + 1 or 2n + 2, wer e observed) and polyploidy (4n). The induction of chromosome gaps and breaks was less evident. Methyl thiophanate significantly induced micr onuclei, but it was less effective than benomyl and MBC. Our results s howed that micronuclei are a good indicator of aneugenic effects in mo use bone marrow cells. A curvilinear trend test has been devised to fi t the curves originating from the time-dependent responses.