Fig. 2. Assembly and disassembly of CENPs on an integrated alphoid YAC. Metaphase chromosomes from the cell lines 7C5HT1-19 (A-F) and B13HT1 (M-O) were analyzed by FISH with the 21-I probe (red in A,B) or the YAC arm probe (red in C-F,M-O), in combination with immunofluorescence using antibodies against CENPs (green in A-F,M-O). Scale bars: 2 µm. Chromosomes were counterstained with DAPI (blue). Arrowheads indicate the integration sites of the alphoid YAC. (G-L) Plots of the intensity profile of immunofluorescence signals (black) for anti-CENP antibodies and FISH signals (red) along the dotted line on chromosome 16 shown in A-F. Intensities were measured between the positions marked by the star and the asterisk, as shown in merged images of A-F. (P) The intensity of CENP-B immunofluorescence at each alphoid YAC integration site relative to that of the resident centromere on chromosome 16 was plotted. The red dotted line indicates the lower limit of CENP-B signal that is above background level. (Q) The proportion of cells containing the CENPs signals on the alphoid YAC DNA sites. Bars indicate s.e.m. (standard error of mean).