High-resolution, human-bovine comparative mapping based on a closed YAC contig spanning the bovine mh locus

A closed YAC contig spanning the mh locus was assembled by STS content mapp ing with seven microsatellite markers, eight genes or EST, and nine STS cor responding to YAC ends. The contig comprises 27 YACs, has an average depth of 4.3 YACs, and spans an estimated 1.2 Mb. A linkage map was constructed b ased on five of the microsatellite markers anchored to the contig and shown to span 7 cM, yielding a ratio of 160 kb/1 cM for the corresponding chromo some region. Comparative mapping data indicate that the constructed contig spans an evolutionary breakpoint connecting two chromosome segments that ar e syntenic but not adjacent in the human. Consolidation of human gene order by means of whole genome radiation hybrids and its comparison with the bov ine order as inferred from the contig confirm conservation of gene order wi thin segments.