Analysis Association Between Single Nucleotide Polymorphisms Of GH,GHR&IGF-1and Growth Traits In Tibetan Minipigs

OBJECTIVE:In the this study, Growth hormone (GH), Growth hormone receptor (GHR), Pituitary specific transcription factor-1(PIT-1), Somatostatin (SS) and Ghrelin assumed as candidate genes with purpose to fine the molecular evidences related to the growth retardation of Tibetan minipigs. The GH, GHR and IGF-1gene has been implicated as a candidate gene for the regulation of Tibetan minipigs growth traits.METHODS:PCR-RFLP was applied to analyze the polymorphism of GH gene in Tibet miniature pig. We analyzed exon3of GHR and IGF-1gene polymorphism of Tibetan minipigs by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing. The association analysis between gene polymorphism and Tibetan minipigs growth traits were count.RESULTS:The PCR products were cut by Apal, and produced two alleles: A(449bp+101bp+55bp) and B(316bp+133bp+101bp+55bp)。 The allele frequency of A was higher than B. The frequency of the AA genotype is higher than the AB and BB genotype. The association analysis results show that the effect of GH mutation was found on BW, Body length (BL), Chest circumference (CC) and Abdomen circumference (AC) in aged6-8months, BW, BL, WH, CC and AC in aged 9-11months(P<0.05).One single nucleotide polymorphism (A85C) was found on exon9of GHR gene. In GHR gene, Tibetan minipigs exhibit moderate polymorphism(PIC=0.295) at A85C. Statistical analysis of genotype frequencies revealed that T allele was dominant in Tibetan minipigs at A85C locus. The association analysis results show that the effect of GHR mutation was only found on Chest circumference (CC) in aged3-5months. There is no association in others.One single nucleotide polymorphism (T40C) was found on exon3of IGF-1gene. Statistical analysis of genotype frequencies revealed that T allele was dominant in Tibetan minipigs at T40C locus. The association analysis results show that the effect of IGF-1mutation was found on BW, Body length (BL), and Chest circumference (CC) in aged6-8months, BW in aged9-11months (P<0.05).We speculated that the pigs with TT genotype grew more rapidly than those with TC genotype.TC genotype of Tibetan minipig had the smaller body type. This information provides a theoretical basis for the genetic background of Tibetan minipigs.CONCLUTIONS:By PCR-RFLP of GH gene, the A allele frequency of the Tibet miniature pigs are higher. The association analysis results show that the pigs with AA genotype grew more rapidly than those with AB genotype and BB genotype.AA genotype of Tibetan minipig had the smaller body type.The association analysis results show that the effect of GHR mutation was almost not found.The association analysis results of IGF-1show that the pigs with TT genotype grew more rapidly than those with TC genotype.TC genotype of Tibetan minipig had the smaller body type.