Figure 5

FISH-based characterization of an ancestral chromosome fusion site in the Indian muntjac genome. (a) Sequence IMFS3 (Table 1) was derived from three overlapping Indian muntjac BACs (BACs a-c), and contains the features expected of an ancestral chromosome fusion site (Figure 3). Each of the BACs was mapped by FISH to metaphase chromosomes from Indian muntjac cells. A probe (red circle) derived from the end of the middle clone (BAC a) was used to isolate an overlapping Indian muntjac BAC (BAC b) as well as two orthologous Chinese muntjac BACs (BACs d and e); the latter were sequenced, confirmed to be orthologous to the telomeric end of IMFS3, and designated CMTel3 (Table 2). (b) FISH studies were performed on the five clones (BACs a-e) depicted in (a). Indian muntjac BAC [GenBank:AC152355] (BAC a) hybridized to an interstitial position on chromosome 1 and at the neck of chromosome 3+X (shown in Figure 1b). The FISH composite image (upper row, far left) generated by merging the DAPI (blue), Spectrum Orange (red), and Spectrum Green (green) channels shows BAC [GenBank:AC197641] (BAC b; in red) hybridizing to an interstitial site on Indian muntjac chromosome 1 (arrow) and BAC [GenBank:AC166188] (BAC c; in green) hybridizing to the latter position as well as other centromeric and interstitial sites (arrowhead), reflecting its high content of satellite I and duplicated segments; an enlarged view of chromosome 1 (upper row, far right) confirms the site of co-hybridization of these two BACs. The gray scale channel images (upper row, middle) corresponding to the enlarged view of chromosome 1 show the hybridization pattern of each BAC separately. A similar FISH study with Chinese muntjac chromosomes is shown on the bottom row, with Chinese muntjac BAC [GenBank:AC196603] (BAC d; in green) and BAC [GenBank:AC198815] (BAC e; in red) co-hybridizing to a telomeric position on a pair of chromosomes (arrowheads). The two gray scale channel images show the hybridization pattern of each BAC separately. Synteny analysis suggests that the site of hybridization of these two BACs is Chinese muntjac chromosome 22 (see text).