Cytogenetic assignment of 53 microsatellites from the USDA-MARC porcine genetic map

This study provides 53 new fluorescent in situ hybridization cytogenetic as signments for microsatellite markers linked on the swine genetic map. Forty microsatellites are physically assigned for the first time. The chromosoma l locations of eight markers were either confirmed or refined, while five l oci were assigned to locations different from those given in previous repor ts. Markers were selected to provide physical anchors based on their presum ed proximity to centromeres or telomeres and at approximately 30 cM interva ls across the genetic map. The number of physical anchors for pig (SSC) chr omosomes 8, 15, and 18 linkage groups was significantly improved. Centromer ic regions were localized to areas less than 10 cM. for SSC 1, 2, 3, 6, 7, 8, and 9. Although the recombination rate was generally higher across small biarmed chromosomes and lowest for large acrocentric chromosomes, two regi ons with particularly low (1q2.1 --> q2.9 and 13q2.3 --> q4.1) and three re gions with extremely high (5p1.5-->p1.2, 6p1.4-->p1.3, and 12p1.5 --> p1.4) rates of recombination were detected. These assignments represent an overa ll 10% increase in the number of physically assigned markers in Sus scrofa and more than a 20% increase in the number of Type II loci assigned to the pig cytogenetic map.