Abstract: Taking European pig breeds as control, the single nucleotide polymorphisms of paraoxonase (PON1) gene were investigated in Guizhou indigenous pig breeds, including Xiang, Nuogu, Luobo and Kele pig breeds, using allele-specific polymerase chain reaction (AS-PCR) method. The results showed that two nucleotide mutations, A/T and G/A were found out from site 163/165, and one with C/T variation from site 515 of PON1 gene of porcine population. Three genotypes, wild, mutant, and heterozygous, of site 163/165 and 515 were detected from Guizhou indigenous pig breeds and European ones. Frequencies of genotypes and alleles at site 515 in Guizhou pig breeds were not different from that of European pig breeds (P>0.05). But it was significant at site 163/165 of PON1 gene. Allele A was dominant in Guizhou pig breeds with frequency of 83.7%, and were higher than European pig breeds (25.2%). The mutated nucleotides at site 163/165 encoded methionine (Met 55), which was consistent with that of human patients with metabolic syndrome. The wild genotype of PON1 at site 163/165 (allele B), dominated in Europe pig breeds, contained residue leucine (Leu 55) which was corresponding to population without metabolism disorder. Taking the crystal structure of human PON1 protein as template, three-dimensional structure of PON1 from Xiang pig was deduced. The location of Met 55 Leu was next to the calcium binding site in PON1 structure. It had been demonstrated that the hydrolase activity of PON1-M55 decreased and related to the metabolism disorder in human patients, and the polymorphism of PON1 gene was correlated with the meat quality in pig. It suggested that the polymorphism at site 163/165 in PON1 gene might contribute to the improvement of meat quality in Guizhou indigenous pig breeds.

Key words: Guizhou indigenous pig breeds; paraoxonase 1 gene; polymorphism; three-dimension structure; meat quality