Application of antikinetochore antibody staining (CREST staining) to micronuclei in erythrocytes induced <i>in vivo</i>

Micronuclei (MN) can be formed by acentric chromosome fragments or whole lagging chromosomes. In order to discriminate MN produced by chromosome breakage from those arising from spindle malfunction a staining method using immunofluorescent kinetochore antibodies has been applied successfully in vitro. In the present study MN in polychromatic erythrocytes of mouse bone marrow cells induced in vivo by the spindle poison colchicine (COL) and the clastogen mitomycin C (MMC) were analysed after CREST staining. The staining method was modified by using pretreatment with detergents in order to allow a good penetration of the antibodies into the MN. About 66% of the MN induced by COL in contrast to only 4.5% of the MMC induced MN were CREST-positive. The preliminary results show that the CREST staining is also in MN induced in vivo capable of detecting the origin of MN and to discriminate between the spindle damaging or clastogenic activity of environmental agents. The method described will give supplementary information about MN, it cannot substitute for the common micronucleus test.