DNA sequence of SSCP haplotypes at the bovine growth hormone (bGH) gene

Previous studies using SSCP and PCR-RFLP methodologies uncovered nine polym orphic sites within the bGH gene, defining eight intragenic haplotypes fall ing into two main groups. In the present study we report the DNA sequence o f these eight haplotypes. A total of 1494 bp were sequenced uncovering a to tal of 12 sequence variants. Haplotypes within groups differed among themse lves at one or two sites; compared across groups, haplotypes of the two gro ups differed consistently at six sites, each of which was monomorphic withi n the respective groups. This comes to 4 differentiating sites per kb, sugg esting that the two haplotype groups began to diverge about 400 000 years a go. This corresponds approximately to the estimated time of divergence of t he Bos taurus and Bos indicus lineages, raising the possibility, supported by other evidence, that the two haplotype classes represent taurine and ind icine haplotypes, respectively. Nucleotide sequence divergence of taurine a nd indicine genomes of this magnitude has far reaching implications with re spect to QTL mapping and marker assisted selection in breeds derived from t aurine x indicine crosses.