Comparative analysis of Y chromosome structure in Bos taurus and B. indicus by FISH using region-specific, microdissected, and locus-specific DNA probes.

Results of fluorescence in situ hybridization (FISH) of Bos taurus and B. indicus Y chromosomes using the bovine locus-specific Y probes BC1.2 and lambda ES6.0 and region-specific probes of B. indicus and B. taurus Y chromosomes, which were generated by microdissection and DOP-PCR, indicate that the Y chromosomes of B. indicus (BIN Y) and B. taurus (BTA Y) differ by a pericentric inversion. Parts of the short and long arms of the Y chromosome in B. taurus and the distal half of the Y chromosome in B. indicus were microdissected, amplified by DOP-PCR, biotinylated, and rehybridized in situ to the corresponding metaphase chromosomes to test the chromosome fragment specificity of the DNA probes. The region-specific painting probes were used for hybridization to metaphase chromosomes of the other species. The DNA painting probes BTA Yp12 and BTA Yq12.1-ter derived from BTA Y hybridized to the distal and proximal halves of BIN Y, respectively. Complex hybridization signals on BTA Yq12.1-->qter were generated with the DNA probe BIN Yqcen-centr (centromere-central) after FISH. The results demonstrate that BTA Yp is homologous to the distal half of BIN Y and that BTA Yq corresponds to the proximal part of BIN Yq. Hybridization of the Y chromosome-specific DNA probes lambda ES6.0 to BTA Yp12-->p11 and near to the telomere of BIN Y and BC1.2 to BTA Yq12-->q13 and to the telomere of BIN Y indicate an opposite orientation of the homologous chromosome fragments BTA Yp and of the distal half of BIN Yq.