Iowa State University Breeding/Physiology Mapping of Three Genes to Pig Chromosome 7q Demonstrates the Similarity with Human Chromosomes 14q and 15q

Previous data have suggested the presence of pork quality quantitative trait loci (QTL) on pig chromosome (SSC) 7q. Improving the resolution of the pig-human-mouse comparative map in this region can facilitate the search for candidate genes for these possible QTL. Therefore, three genes, the cytochrome P-450, subfamily I, polypeptide 1 (CYP1A1), somatostatin receptor 1 (SSTR1), and transcription termination factor 1 (TTF1) genes, all with expected location on pig chromosome 7 based on painting studies, were selected for mapping in the pig. Porcine sequence tagged sites (STSs) spanning 0.9- 1.5 kb genomic DNA sequence were generated and all genes were physically assigned to SSC7q12-q23, q26 using a pig/rodent somatic cell hybrid panel. Direct sequencing of polymerase chain reaction (PCR) products from different breeds revealed single nucleotide polymorphisms (SNPs) in all genes. The SSTR1 and CYP1A1 single SNPs allowed simple genotyping with PCR-restriction fragment length polymorphism (RFLP) analysis, and were informative for linkage mapping with the PiGMaP reference families. This revealed that SSTR1 is closely linked to CYP1A1 (0.0 cM; LOD = 11.1) and ANPEP (0.0 cM; LOD = 9.0), which refined the localization of a breakpoint in the linkage map between regions with homology to human chromosome 15q (represented by CYP1A1 and ANPEP) and proximal 14q (represented by SSTR1). Moreover, multipoint linkage data suggest inverse homology between human chromosome 14q11-q13 and and pig chomosome 7q. The TTF1 SNP was confirmed by allele-specific PCR but was not informative in any of the families used for linkage analysis