Mapping four genes from human chromosome 4 to porcine chromosome 8 furtherdevelops the comparative map for an economically important chromosome of the swine genome

Because porcine chromosome (SSC) 8 has become the focal point of many effor ts aimed at identifying quantitative trait loci affecting ovulation rate, g enes distributed across human chromosome (HSA) 4 were physically mapped in the pig. A more refined comparative map of this region for these two specie s was produced. In this study, four genes were selected based on their loca tion in the human genome, the availability of nucleotide sequence and their genomic organization. The genes selected were fibroblast growth factor bas ic (FGF2; HSA 4q25-27), gonadotropin releasing hormone receptor (GNRHR; HSA 4q13), phosphodiesterase 6 B (PDE6B; HSA 4p16.3) and aminopeptidase S (PEP S; HSA 4p11-q12). Genomic libraries were screened via PCR and clones were p hysically assigned using fluorescence in situ hybridization (FISH). These f our genes from HSA 4 were physically mapped to SSC 8p2.3 (PDE6B), 8p1.1(PEP S), 8q1.1-1.2 (GNRHR) and 8q2.2-2.4 (FGF2). These assignments provide addit ional benchmarks for the comparative map and help define the level of gene order conserved between HSA 4 and SSC 8.