Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 19, 1995
Publication Date: N/A
Interpretive Summary: The large scale generation of random microsatellite markers for the porcine genome is drawing to a close. With this skeletal map in hand, we can now proceed to identify areas of the genome for which it is desirable and/or necessary to increase marker density or fill in large intervals. Currently available technologies of chromosome microdissection and generation of chromosome segment-specific libraries permit this approach if the linkage and cytogenetic maps are sufficiently integrated. Integration can be rapidly achieved by a directed isolation of mapped markers on DNA segments of sufficient size for in situ hybridization. Application of an iterative screening process to isolate cosmids carrying SSC7 markers has produced a highly integrated physical and genetic linkage map of this swine chromosome. We demonstrate that the linkage map encompasses the entire chromosome, with significant variation of recombination rate as a function of position. In addition, FISH analysis of SLA markers reveals that the complex spans the centromere.
The first integrated physical and genetic linkage map encompassing the entire swine chromosome 7 (SSC7) reveals that the porcine Major Histocompatibility Complex (SLA) spans the centromere. An SLA class II antigen gene lies on the q arm, while class I and III genes lie on the p arm, suggesting that presence of a centromere within the SLA does not preclude a functional complex. 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 recombination rates as a function of position along the chromosome, and the SLA lies in the region with the lowest rate. Furthermore, the directed integration approach used in this study was more efficient than previous efforts that emphasized the screening of large insert libraries for random microsatellites.