THE CENTROMERES OF THE INDIAN MUNTJAC - EVIDENCE FOR THE EXISTENCE OFMULTIPLE CENTROMERES

Unlike the centromeres of other species, the 'compound' centromeres of the Indian muntjac span over exceptionally extended regions (Brinkley et al., 1984). We extend this concept and show that some of these cen tromeres are divisible into several chromomeres in which the light sta ining regions alternate with the dark staining C-band positive segment s. Unlike the centromeres of other species where the centromere replic ates as one unit, the replication of the sub-units constituting the ce ntromere of the X-chromosome in the muntjac occurs at different times as at least three independent segments. The CREST staining of the cent romere regions of even the smallest (Y-2) chromosome is interrupted by non-staining segments. Electron microscopy shows similar interruption s in the continuity of the trilamellar kinetochore. Sister chromatid e xchanges occur in the region of the centromeres and chromatid breaks w ithin the centromere region occur in the non-fluorescent segments. We interpret these data to suggest that the centromere regions of the Ind ian muntjac are made up of independent multiple centromeres interrupte d by non-centromeric chromatin. Relevance of these parameters in mutag enesis is briefly discussed.