Research Of Polymorphism Of MSTN Gene As Molecular Markers In Plgs

One of objectives of pig breeding is to increase lean meat quantity. Myostatin(MSTN) belongs to the transforming growth factor- β superfamily, and is expressed specifically in developing and mature skeletal muscle. The expression products of MSTN gene is growth/differentiation factor-8(GDF-8), which inhibits muscle growth and differentiation. Mutations occurred in the conservative regions of MSTN gene may affect even cause the loss of its function of muscle inhibiting, thereby causing celluar hyperplasia and hypertrophy of the skeletal muscle. In this study the polymorphism of MSTN gene and its relationship with production traits were performed to find a molecular marker for porcine lean meat percentage, thereby to provide a new method for pig breeding. DNA samples of 47"Double muscled"LargeWhite and 20 Denmark lined LargeWhite were isolated, PCR-SSCP was used to investigate the polymorphism in the second and third exons of the MSTN gene, the PCR fragments with polymorphism were cloned and sequenced to find single nucleotide polymorphism.1. Three pairs of primers were used to detect the polymorphism in the second and third exons of the MSTN gene by PCR-SSCP in "Double Muscled" LargeWhite and Denmark lined LargeWhite. The results showed there were three genotypes (CC, CT, TT) in the second exon with allele frequencies of 0. 417C, 0. 583T, 0. 225C, 0. 775T respectively and there were two genotypes (GG, AG) in the third exon with allele frequencies of 0. 341A,0.659G,0.300A, 0. 700G respectively.2. The fragment with SSCP polymorphism in the third exon was cloned and sequenced, the sequencing results showed that there was a single nucleotide mutation, i. e A→G at 1008,this mutation did not change the amino acid but brought an Apal site.3. The fragment with SSCP polymorphism in the second exon was cloned and sequenced, the sequencing results showed that there was a single nucleotide mutation, i. e G→T at 480 , this mutation did not change its encoding amino acid.4. The relationship between polymorphism in the second and third exons among the 47 "Double muscled" LargeWhite were analysed. Variance analysis showed that there was no significant relationship between the polymorphism in the second exon and back fat thickness and lean meat percentage. But t test showed that there was significant relationship between the polymorphism in the third exon and back fat thickness (P<0. 04),there was also a relationship between the polymorphism in the third exon and lean meat percentage, but not significant(P<0. 07).5. Using "Double muscled" LargeWhite as experimental materials, PCR-RFLP molecular marker technique was established by PCR amplification with primer 1 and then digested with Apal.