Use of bovine EST data and human genomic sequences to map 100 gene-specific bovine markers.

A system to use bovine EST data in conjunction with human genomic sequence to improve the bovine linkage map over the entire genome or on specific chromosomes was evaluated. Bovine EST sequence was used to provide primer sequences corresponding to bovine genes, while human genomic sequence directed primer design to flank introns and produce amplicons of appropriate size for efficient direct sequencing. The sequence tagged sites (STS) produced in this way from the four sires of the MARC reference families were examined for single nucleotide polymorphisms (SNPs) that could be used to map the corresponding genes. With this approach, along with a primer/extension mass spectrometry SNP genotyping assay, 100 ESTs were placed on the bovine genetic linkage map. The first 70 were chosen at random from bovine EST-human genomic comparisons. An additional 30 ESTs were successfully mapped to bovine Chromosome 19 (BTA19), and comparison of the resulting BTA19 map to the position of the corresponding human orthologs on the HSA17 draft sequences revealed differences in the spacing and order of genes. Over 80% of successful amplicons contained SNPs, indicating that this is an efficient approach to generating EST-associated genetic markers. We have demonstrated the feasibility of constructing a linkage map based on SNPs associated with ESTs and the plausibility of utilizing EST, comparative mapping information, and human sequence data to target regions of the bovine genome for SNP marker development.