Isolation of micronuclei from mouse blood and fluorescence in situ hybridization with a mouse centromeric DNA probe.

Spontaneously existing and chemically induced micronuclei were isolated from mouse blood. 50 microliters of cardiac blood was diluted with PBS and centrifuged. After this, the cell pellet was subjected to hypotonic treatment, fixed with acetic acid-methanol (1:3), and the lysate was filtrated through a 2-microns polycarbonate nucleopore membrane. Isolated micronuclei were air-dried on a glass slide and subjected to fluorescence in situ hybridization (FISH) using a mouse centromeric gamma satellite probe. Approximately half of the micronuclei isolated from vehicle control mice showed centromere signal(s). In these preliminary studies, the proportion of centromere-positive micronuclei was increased by treatment with spindle poisons (colchicine and vinblastine sulfate), decreased only slightly by 1-beta-D-arabinofuranosylcytosine, and was generally unaffected by mitomycin C.