INTEGRATING THE PORCINE PHYSICAL AND LINKAGE MAP USING COSMID-DERIVEDMARKERS

An essential part in the development of informative linkage maps is to include genetic markers that have been anchored by physical mapping. Here a set of 18 porcine cosmid-derived genetic markers are reported t hat have been mapped by linkge analysis, and that also have been physi cally localized by fluorescence in situ hybridization (FISH). Three di fferent strategies were used to establish polymorphic markers from the cosmid clones. Firstly, dinucleotide microsatellite loci were derived by sequencing cosmid subclones containing (CA)n repeats. Secondly, va riable SINE 3' poly(A) tracts (SINEVA) were identified by direct SINE- PCR amplification of cosmid clones. Thirdly, the cosmids were used in Southern blot hybridization to detect restriction fragment length poly morphisms (RFLPs). Compared with the most recent consensus compilation of the porcine gene map, the present assignment of markers to chromos omes 2p, 3, 4, 10, 12q, and 16 represents the first loci mapped to the se chromosomes, for which linkage as well as in situ data are now avai lable.