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

Abstract.

Several quantitative trait loci (QTLs) (vertebrate number, birth weight, age at puberty, growth rate, gestation length, and backfat depth) have been independently mapped to the distal region of swine Chromosome (SSC) 1q in several resource populations. In order to improve the map resolution and refine these QTLs more precisely on SSC1q, we have isolated and mapped additional microsatellites (ms), using chromosome microdissection and radiation hybrid (RH) mapping. Five copies of the telomeric region of SSC1q were microdissected from metaphase spreads and pooled. The chromosomal fragment DNA was randomly amplified by using degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR), enriched for ms, and subcloned into a PCR vector. Screening of subsequent clones with ms probes identified 23 unique ms sequences. Fifteen of these (65%) were subjected to radiation hybrid (RH) mapping by using the INRA-University of Minnesota porcine RH panel (IMpRH); and the remaining eight were not suited for the RH mapping. Twelve microsatellites were assigned to SSC1q telomeric region of IMpRH map (LOD >6), and three remain unlinked (LOD <6). Out of the 15 microsatellite markers, 9 were polymorphic in NIAI reference population based on the Meishan and Göttingen miniature pig. In summary, we have used microdissection and radiation hybrid 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.