Development and initial characterization of a Bos taurus x B. gaurus interspecific hybrid backcross panel.

A panel of 40 Bos taurus x B. gaurus (gaur) interspecific hybrid backcross off spring was constructed for use as a tool in refining and improving the resolution of the bovine gene map. The gaur (2n = 58) is characterized karyotypically by a 2; 28 Robertsonian translocation with respect to the cattle karyotype (2n = 60). This translocation was used as a centromeric marker to directionally orient linkage maps of B. taurus (BTA) chromosomes 2 and 28. The initial linkage analysis of this panel consisted primarily of genes or DNA segments containing microsatellites previously placed on bovine maps. Two new markers, NRAMP1 and ACTA1, were added to the linkage maps on BTA2 and BTA28, respectively. Additionally, fibroblast cultures from fetal tissue of each offspring were analyzed cytogenetically at early passages. In all cases, the translocation chromosome was inherited in a balanced condition, and only one cell line possessed a chromosome abnormality. This aberrant line was determined to be trisomic, 61,XXX.