Analysis by fluorescence in situ hybridization with a mouse gamma satellite DNA probe of isolated micronuclei induced in mice by two clastogens and two spindle poisons.

The presence of centromeric DNA was studied in micronuclei isolated from the blood of male ddY mice after five weekly intraperitoneal injections of mitomycin C (MMC), 1-beta-D-arabinofuranosylcytosine (Ara-C), colchicine (COL) or vinblastine sulfate (VBL). In agreement with our earlier findings, about half of the micronuclei isolated from vehicle control mice showed centromere signals as analyzed by fluorescence in situ hybridization (FISH) with a mouse major (gamma) satellite DNA probe. In an earlier experiment with mice acutely exposed to the same chemicals, the clastogens MMC and Ara-C did not reduce the proportion of micronuclei with centromere signals. In the present study, however, MMC and Ara-C decreased the proportion of micronuclei with centromeres. In contrast, the spindle poisons COL and VBL increased the proportion of micronuclei that contained centromeres.