The Study On The Traits And PIT-1 Gene Polymorphisms In Xiang Pigs

Xiang pig is famous miniature pig breed and it has become perfect animal model for biomedical reserch because of it's steady dwarfism. It is important to find the major gene about the dwarfism of Xiang pig and study their heredity mechanisms to comprehensively appraise, utilize and protect the pig breed.The study of growth performances, physiological and biochemical traits of Xiang pigs were carried out at the breeding farm in Shanghai Jiaotong University. PCR and DNA sequence measuring were used to analysis the polymorphisms of the PIT-1 gene in Xiang pig and contrast breeds (Shanghai White pig and Yorkshire pig). The semi-quantitative analysis in expression quantity of PIT-1, GH, PRL and TSH-β gene of pigs were conducted by RT-PCR for finding out the effect of gene mutation on the function of PIT-1.The results showed the following facts: The dwarfism of Xiang pig was obvious and its physiological and biochemical traits were similar to human being. No SNP was found in the fifth and the sixth exon of PIT-1 gene in the three breeds, however, the mutation of C-->T, which was probably independent of dwarfism of Xiang pigs, was revealed in 272 in the published PIT-1 gene sequence in experimental pig except 1/2 Yorkshire pigs. There were SNPs in the fourth and the fifth intron of PIT-1 gene in the three breeds, and the mutations of G-->A appeared in 963 and 1429 in the published PIT-1 gene sequence of Xiang pigs. The expression quantity of PIT-1, GH, PRL and TSH- β gene in Xiang pig was significantly less than both Shanghai White pig and Yorkshire pig. The results demonstrated that the two mutation in intron of PIT-1 gene in Xiang pig probably led to decline of expression quantity of PIT-1 gene, it then weakened the activation function to the transcription and expression of GH, PRL and TSH- β gene which promoted excretion of relevant hormones, and it finally hindered the growth of Xiang pigs.