Submitted to: Colloquium on Domestic Animal Cytogenetics and Gene Mapping
Publication Type: Proceedings
Publication Acceptance Date: August 22, 1997
Publication Date: N/A
Integration of informative, physically anchored loci into a comprehensive linkage map significantly improves resolution and estimates of chromosomal coverage. The latest version of the porcine linkage map merged three previously published maps by typing 1,042 linked loci spanning 2286.2 cM. The map was integrated with 123 physical assignments by FISH showing that most of the pig linkage groups cover the entire length of each chromosome. Despite this integration, few markers in the pericentromeric regions have been physically assigned which makes it difficult to predict the physical coverage of the p and q arms and the location of the centromere. We isolated YAC clones containing eight microsatellite markers for four linkage groups (SSC1, 4, 8 and 10). Markers were physically assigned to the distal region of the p arm for SSC1 and SSC8 and to the distal region of the q arm for SSC4 and SSC10. The remaining markers were assigned to the proximal portion of the q arm for SSC1, SSC4, SSC8 and SSC10. The physical assignments span 57-81% of the p arm (SSC4 and SSC10) and 67-91% (SSC10 and SSC4) of the q arm's length. The estimated physical coverage of the linkage group (telomere to telomere) ranged among 95% to 92.5% of the chromosome (SSC1 and SSC8, respectively). The centromere is located within a 10 cM segment for SSC1, 4 and 8 and 17 cM for SSC10. These centromere linkage distances represent 8, 14, 18 and 19% (SSC1, 4, 8 and 10, respectively) of the total chromosome's physical length. These results allow us to improve the resolution of the centromere's location in the linkage groups and indicate the need to increase the density of physically assigned markers in these regions of other linkage groups.