Submitted to: World Congress of Genetics Applied in Livestock Production
Publication Type: Proceedings
Publication Acceptance Date: May 15, 1994
Publication Date: N/A
Interpretive Summary: This review is for an international meeting on "Genetics as applied to livestock production." It describes the use of a procedure to isolate the individual chromosomes in the pig, and explains how we have been successful in isolating chromosome #6. After sorting for swine chromosome #6, the DNA from this chromosome was used to construct a genetic library. This library contains small fragments of DNA (clones) that together represent the entire amount of DNA found in chromosome #6. This swine chromosome 6 library is being searched for clones of DNA that contain repetitive copies of the sequence (CA). These (CA)n repeats, called microsatellites, are found abundantly throughout the swine genome and are used as genetic markers to identify the areas of the chromosome where they are located. To date, we have found 17 (CA)n repeat containing DNA clones, and are currently analyzing them to see if they are unique. The detection of new microsatellites will help in further defining the genomic map of swine chromosome 6. This is important because we are interested in further defining the area of chromosome 6 where the Porcine Stress Syndrome (PSS) gene is located, since there also appears to be positive carcass trait gene(s) linked this gene.
A swine chromosome 6 specific library was generated using size fractionated DNA isolated from chromosomes sorted by flow cytometry. Procedures have been established in our laboratory to reproducibly prepare high quality chromosomes from PHA stimulated swine peripheral blood lymphocytes and to sort individual chromosomes after staining with Hoechst 33258 and chromomycin A3. DNA from 1,000 isolated chromosome 6 was then Sau3A digested, cloned into pBluescript SK II+, and PCR amplified; 300-600bp DNA fragments were isolated from the amplified DNA and cloned to produce the chromosome 6 specific library. Our chromosome 6 library has already yielded 17 clones containing (CA)n repeats and is now being screened for more (CA)n microsatellite repeats as well as other repeat sequences. New microsatellite markers on chromosome 6 will be used to develop a more detailed map of the region where the genes that encode positive carcass traits and Porcine Stress Syndrome (PSS) are found.