Source and Description of Probe. Microsatellite locus S0511, originally identified from a porcine genomic library screened with d(CA)9, was used in these studies. Primers MS6F: 5¢AAAAACACGGAA GCAATAGAAATGTC-3¢ and MS5R: 5¢-GTCCATC CATGTTGCTCCAAATGG-3¢ were used in a PCR protocol to amplify sequence specific alleles. Primer MS6F was labeled using [g-32P]dATP (3,000 Ci/mmol, DuPont NEN) and polynucleotide kinase (New England Biolabs).