Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 3, 1997
Publication Date: N/A
Interpretive Summary: We have produced a comprehensive linkage map for pig chromosome 7 which contains 86 informative markers by combining genotypic data collected in four different reference populations. The map spans the entire length of pig chromosome 7 and has sufficient marker density to identify loci affecting economically important traits. However, additional physically assigned markers associated with coding sequences will be needed to establish the extent of conserved synteny and order between pig chromosome 7 and its human and mouse homologues. Heterologous chromosomal painting of pig chromosomes with human chromosome-specific libraries showed that pig chromosome 7 contains segments from human chromosome 6, 14 and 15, and suggested that a minimum of three chromosomal rearrangements have taken place during the evolution of these regions in the two species. Currently, not enough genes have been assigned to pig chromosome 7 to determine where the evolutionary break points reside. This information is necessary to fully exploit the rapidly evolving human transcript map for positional candidate cloning of trait loci in the pig.
The First International Workshop on Swine Chromosome 7 (SSC7) was held in Minnesuing, Wisconsin, USA from September 21-24, 1995. The objective was to develop a comprehensive linkage map for porcine chromosome 7 by combining genotypic data from four swine reference populations. Genotypic data were contributed by the U.S. Meat Animal Research Center, University of Minnesota, PiGMaP consortium, and Scandinavian consortium. Primers for selected STS markers to be genotyped across the reference populations were exchanged to integrate individual maps of SSC7. Eighty- six loci representing microsatellite, minisatellite, SSCP, RFLP, erythrocyte antigen and protein polymorphisms were genotyped. Eighteen genes including 12 markers within class I (4), II (4) and III (4) regions of the swine major histocompatibility complex (SLA) were mapped. Forty-two markers were either genotyped on more than one population or included in a haplotype system and used to develop skeletal linkage maps which spanned 147.6, 212.7 and 179.5 cM for the male, female and sex-average maps, respectively. A comprehensive linkage map was developed incorporating those markers with more than 30 informative meioses. The comprehensive map was slightly longer than the skeletal map, at 153.3, 215.3 and 183.8 cM, respectively with only three intervals greater than 10 cM. These results significantly improve the genetic resolution of the porcine chromosome 7 map and represents an accurate approach to merge genetic maps produced in different reference populations.