Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2002
Publication Date: 12/1/2002
Citation: NONNEMAN, D.J., ROHRER, G.A. LINKAGE MAPPING OF PORCINE DGAT1 TO A REGION OF PORCINE CHROMOSOME 4 THAT CONTAINS QTL FOR GROWTH AND FATNESS. ANIMAL GENETICS. 2002. v. 33. p. 472-473. Interpretive Summary: Diacylglycerol acyltransferase (DGAT1) is a microsomal enzyme that catalyzes the final and only committed step in the formation of triglycerides, which are the major form of stored energy in eukaryotes. DGAT1-deficient mice are viable, lean, able to synthesize triglycerides, and are resistant to diet-induced obesity. DGAT1-deficient females also have a complete absence of milk production. A substitution in the bovine DGAT1 gene has a major effect on milk yield and fat content; therefore, DGAT1 appears to be crucial for lactation. Human DGAT1 maps to 8q24.3, and bi-directional chromosome painting and comparative mapping have identified SSC4 to be syntenic with portions of human chromosomes 1 and 8. Several quantitative trait loci (QTL) for growth and fatness have been identified in swine on chromosome 4 (SSC4). Because DGAT is a candidate for fatness and growth QTL in pigs, we cloned and mapped porcine DGAT1 to determine if it is a positional candidate for quantitative traits. Two-point linkage analysis placed DGAT1 on porcine chromosome 4 with 85 informative meioses. Although DGAT1 does not map within the major QTL interval for backfat thickness or intra-muscular fat in the pig, it does map within suggestive QTL intervals for growth rate, intra-muscular fat, and fatty acid composition. The comparative mapping and nucleotide sequence of porcine DGAT1 will benefit further analysis of growth and fatness QTL in the pig.
Technical Abstract: Diacylglycerol acyltransferase (DGAT1) is a microsomal enzyme that catalyzes the formation of triglycerides, and maps to human chromosome 8q24.3. Several QTL for growth and fatness have been identified in swine on porcine chromosome 4 (SSC4). Bi-directional chromosome painting and comparative mapping have identified SSC4 to be syntenic with portions of human chromosome 8. DGAT1-deficient mice are lean and resistant to obesity, and a mutation in the bovine DGAT gene has a major effect on milk yield and fat content. A 1935bp full-length cDNA and approximately 10kb of porcine DGAT1 gene sequence was determined from cDNA and cosmid libraries and confirmed with genomic sequences. Porcine DGAT1 was mapped to SSC4, relative position 0.0 cM, using a PCR/RFLP found in intron 2. DGAT1 is a candidate gene that may contribute to variation in pork fatness and growth.