POSITIONAL CLONING OF A MAJOR GENE (RN) CONTROLLING GLYCOGEN CONTENT IN PIG SKELETAL MUSCLE

¹ Dept. Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden

² INRA, Toulouse, France

³ Institute of Animal Breeding and Husbandry, Christian-Albrechts-University, Kiel, Germany

⁴ INRA, Jouy en Josas, France

The porcine RN gene has a large effect on muscle glycogen content and meat quality. The fully dominant RN- allele occurs at a high frequency in the Hampshire breed and increases glycogen content by about 70%. We have previously assigned RN to chromosome 15q2.5 by combined linkage and physical mapping. The region shares conserved synteny with human chromosome 2q33-q36 (Robic et al. 1999, Mammalian Genome 10:565-568.). We are now attempting to identify RN by positional cloning. Pedigree data comprising more than 1,000 informative meioses have been collected for precise linkage mapping of RN. In addition random population samples are available for linkage disequilibrium mapping. A BAC contig of about 2 Mbp spanning the RN region has been completed. The BACs have been used to develop new polymorphic markers (microsatellites and SNPs) for high-resolution linkage and linkage disequilibrium mapping. A comparative map of the region has been constructed using Radiation Hybrid mapping. The data clearly indicate that no candidate gene for RN has yet been mapped to the corresponding regions in humans or mice. The BAC clones containing the RN gene have been used for shot-gun sequencing with the aim to identify all transcripts from the actual region, potential candidate genes are currently being evaluated.