Directed isolation and mapping of microsatellites from swine Chromosome 1qtelomeric region through microdissection and RH mapping

Several quantitative trait loci (QTLs) (vertebrate number, birth weight, ag e at puberty, growth rate, gestation length, and backfat depth) have been i ndependently mapped to the distal region of swine Chromosome (SSC) Iq in se veral resource populations. In order to improve the map resolution and refi ne these QTLs more precisely on SSC1q, we have isolated and mapped addition al microsatellites (ms), using chromosome microdissection and radiation hyb rid (RH) mapping. Five copies of the telomeric region of SSC1q were microdi ssected from metaphase spreads and pooled. The chromosomal fragment DNA was randomly amplified by using degenerate oligonucleotide primed polymerase c hain reaction (DOP-PCR), enriched for ms, and subcloned into a PCR vector. Screening of subsequent clones with ms probes identified 23 unique ms seque nces. Fifteen of these (65%) were subjected to radiation hybrid (RH) mappin g by using the INRA-University of Minnesota porcine RH panel (IMpRH): and t he remaining eight were not suited for the RH mapping. Twelve microsatellit es were assigned to SSC1q telomeric region of IMpRH map (LOD > 6), and thre e remain unlinked (LOD < 6). Out of the 15 microsatellite markers, 9 were p olymorphic in NIAI reference population based on the Meishan and Gottingen miniature pig. In summary, we have used microdissection and radiation hybri d mapping to clone and map 12 new microsatellites to the swine gene map to increase the resolution of SSC1q in the region of known QTLs.