Development of a physical and comparative map of the turkey genome

The recent release of the draft chicken genome sequence provides new opportunities for comparative analysis of other avian genomes, for example, that of the turkey, another major agricultural animal species. A BAC contig physical map of the turkey (or other avian) genome, aligned with the chicken sequence, would provide a valuable resource — a one sequence, two (or more) genomes strategy. Furthermore, such a comparative map would aid in the analysis and application of the chicken sequence itself. A turkey BAC library (11X genome coverage) was previously constructed at the Children’s Hospital of Oakland Research Institute (http://bacpac.chori.org). We performed an initial test to see if chicken sequence-based probes could be used in combination with this BAC library, despite the 25-50 million years of separate evolution of the turkey and chicken genomes. We screened the turkey BAC library with a set of 210 pre-existing chicken overgo probes used previously in constructing the chicken BAC contig physical map. As a result, over 2,000 turkey BACs were identified as containing 176 chicken genes or markers located across much of the chicken genome. As expected, overgos designed from chicken coding exons were most often successful (93%), but even overgos from UTRs, introns and gene flanking regions were surprisingly effective (73-75%). Overgo hybridization probes based on the chicken genome sequence provide a cost-effective, high throughput method that, along with end sequence analysis of turkey BACs, could rapidly generate a physical and comparative BAC contig map for the turkey and/or other avian species.