Generation of an improved cytogenetic and comparative map of Bos taurus chromosome BTA27.

Comparative genome analysis in cattle, human, and mouse identified various evolutionary breakpoints between Bos taurus 27 chromosome (BTA27) and corresponding segments in the Homo sapiens 4 and 8 chromosomes (HSA4, HSA8) and the Mus musculus 8 chromosome (MMU8). The fragmentary cytogenetic location of breaks is based on nine known loci and Zoo-FISH data on BTA27. A comparative mapping approach combining in-silico mapping and physical mapping by fluorescence in-situ hybridization (FISH) revealed an improved cytogenetic map of BTA27 based on 25 new and nine existing assignments of loci. Furthermore, hybrid cell mapping techniques identified and anchored three additional gene loci on BTA27. The BTA27 map was compared with available mapping and annotated sequence data for the chromosome and a generated comparative map displays conserved syntenic chromosome blocks between cattle, human, and mouse. The new anchor loci identify and narrow down evolutionary breakpoints on a cytogenetic level and can help to support the cattle genome assembly and annotation process.