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. ta urus Y chromosomes, which were generated by microdissection and DOP-PC R, 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 lon g arms of the Y chromosome in B. taurus and the distal half of the Y c hromosome in B. indicus were microdissected, amplified by DOP-PCR, bio tinylated, and rehybridized in situ to the corresponding metaphase chr omosomes to test the chromosome fragment specificity of the DNA probes . The region specific painting probes were used for hybridization to m etaphase chromosomes of the other species. The DNA painting probes BTA Yp12 and BTA Yq12.1-ter derived from BTA Y hybridized to the distal a nd proximal halves of BIN Y, respectively. Complex hybridization signa ls on BTA Yq12.1-->qter were generated with the DNA probe BIN Yqcen-ce ntr (centromere-central) after FISH. The results demonstrate that BTA Yp is homologous to the distal half of BIN Y and that BTA Yq correspon ds to the proximal part of BIN Yq. Hybridization of the Y chromosome-s pecific DNA probes lambda ES6.0 to BTA Yp12-->p11 and near to the telo mere 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 fragmen ts BTA Yp and of the distal half of BIN Yq.