DIRECTED INTEGRATION OF THE PHYSICAL AND GENETIC-LINKAGE MAPS OF SWINE CHROMOSOME-7 REVEALS THAT THE SLA SPANS THE CENTROMERE

The first integrated physical and genetic linkage map encompassing the entire swine chromosome 7 (SSC7) reveals that the porcine MHC (SLA) s pans the centromere. A SLA class II antigen gene lies on the q arm, wh ereas class I and III genes lie on the p arm, suggesting that the pres ence of a centromere within the SLA does not preclude a Functional com plex. The SLA appears smaller than other mammalian MHC, as the genetic distance across two class I, three class II, and three class III SLA gene markers is only 1.1 cM. There are significant variations in recom bination rates as a function of position along the chromosome, and the SLA lies in the region with the lowest rate. Furthermore, the directe d integration approach used in this study was more efficient than prev ious efforts that emphasized the screening of large insert libraries f or random microsatellites.