Immunofluorescent and confocal laser cytometric analyses of centromeres in V79 cells

Previously, a modified anticentromere antibody (ACA) technique was established in the V79 Chinese hamster lung cells to simultaneously analyze chromosome damage and aneuploidy induced by various agents. Using this method, cyclophosphamide (CP) was evaluated further in the presence and absence of S9 activation for micronucleus/aneuploidy induction. The specific binding nature of ACA to the centromeric region was also analyzed using a confocal scanning laser cytometry. The results indicated that CP was primarily a clastogen and S9 activation was required for its activity. Vinblastine, the positive control for aneuploidy, produced predominantly centromere containing micronuclei and the addition of S9 was not required for its activity. X-radiation, the positive control for clastogenicity, predominantly produced centromere negative micronuclei confirming its clastogenicity. An evaluation of centromeric region under the standard fluorescence microscope indicated that ACA generally binds to most centromeric regions in a cell. However, by confocal imaging it was found that ACA binds to the central core proteins of the centromere region and not to the peripheral proteins.