Localization of the alpha-S2-casein gene (CASAS2) to the homoeologous cattle, sheep, and goat chromosomes 4 by in situ hybridization.

The alpha-S2-casein gene (CASAS2) has been mapped to the homoeologous cattle, sheep, and goat chromosomes 4 and to the long arm of a bovine chromosome translocation, t(4;8), using nonradioactive in situ hybridization and simultaneous fluorescent R-banding. The t(4;8) has been characterized by GTG-, GBG-, and RBG-banding and by silver staining of nucleolus organizer regions. These results confirm the previous (ISCNDA, 1989) localization of the casein gene group to chromosome 4 of cattle, sheep, and goats. We propose that the discrepancy between our results and earlier assignments of the casein gene group to chromosome 6 of cattle and sheep can be explained by the fact that the chromosome identified as No. 6 in the Reading Conference (1976) report was renamed chromosome 4 in the ISCNDA (1989) standardized karyotype of both species.