Directed integration of the physical and genetic linkage maps of swine chromosome 7 reveals that the SLA spans the centromere.

Abstract

The first integrated physical and genetic linkage map encompassing the entire swine chromosome 7 (SSC7) reveals that the porcine MHC (SLA) spans the centromere. A SLA class !I antigen gene lies on the q arm, whereas class I and !!1 genes lie on the p arm, suggesting that the 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 !, three class !1, and three class !!i SLA gene markers is only I.I 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.Genetic maps of livestock species are currently being developed to provide a worldwide resource for mapping quantitative trait loci, comparative mapping in evolutionary studies, and mapping of pertinent loci in animal models of human disorders. These objectives require a framework of informative markers that can be genotyped economically. Integration of this framework with a cytogenetic map allows evaluation of coverage, genome size, and recombination rates along the chromosome, as well as establishing syntenic relationships among species. Two linkage maps of swine chromosome 7 (SSC7) have been reported, one that includes 11 Archibald et al. 1995) and one with 17 ) microsatellite markers. The two maps have only one marker in common, and both contain intervals >30 cM. The cytogenetic map includes only four relatively low resolution assignments of linked markers with -30% coverage (Ed-

An ordered BAC contig map of the equine major histocompatibility complex

“…However, significant differences in the number and physical organization of the genes within the MHC have been demonstrated in several species of the Artiodactyla (Smith et al, 1995;Band et al, 1998;Chardon et al, 1999;McShane et al, 2001).…”

Construction of a swine BAC library: application to the characterization and mapping of porcine type C endoviral elements

“…Thus, like in man (Tassabehji et al, 1994;Kulski et al, 1997) and mouse (Meruelo et al, 1984;Rossomando and Meruelo, 1986), retroviral elements are associated with the swine MHC region. However, in contrast to the human HLA class II region (Andersson et al, 1998), no PERVcontaining clone has been assigned so far within or near the SLA class II region located at position 7q1.1 (Smith et al, 1995). A third cluster was observed on chromosome 1 at positions 1q2.1, 1q2.3, and 1q2.4.…”

Anchoring of bovine chromosomes 4, 6, 7, 10, and 14 linkage group telomeric ends via FISH analysis of lambda clones

“…Therefore, while the assignment of BL1134 to 10qter demonstrates that the MARC linkage group extends to the telomere, overall coverage of the chromosome cannot be determined until markers from the centromeric end of the linkage groups are physically localized. Directed, iterative screening of cosmid libraries (Smith et al 1995) to obtain large clones containing these markers has been undertaken to establish overall coverage (Lopez et al in preparation).…”

“…The usefulness of the genetic map in identifying ETL is a function of the overall coverage of the genome and the integration of the genetic linkage map with the cytogenetic (physical) map. A major goal of map construction has thus been the generation of polymorphic markers physically localized to regular intervals along the chromosome and at the extremes of the linkage groups, to use for scanning the genome of populations segregating phenotypes of interest (Fries 1993;SolinasToldo et al 1993;Beattie 1994;Ellegren et al 1994;Ferretti et al 1994;Smith et al 1995;Hawkins et al 1995;Mezzelani et al 1995).…”