Relativity Between Polymorphisms Of IGF-Ⅱ Gene And IGF-ⅡR Gene And Growth Traits In Yak

Using IGF-Ⅱgene and IGF-ⅡR gene as main effect candidate gene of growth and development traits in yaks, polymorphism of IGF-Ⅱgene and IGF-ⅡR gene in 380 yaks that come from 5 deferent breeds(Datong Yak, Qinghai plateau Yak, TianzhuYak, Gannan Yak and breeding spices Xinjiang yak) was analyzed by PCR-SSCP, and the PCR products with polymorphism fragments were sequenced to detect single nucleotide polymorphism. The polymorphism of IGF-Ⅱand IGF-ⅡR and the relationship between polymorphism and yak partial production traits were studied in order to find a theoretical foundation for Yak's growth and development, the results show that:(1) The polymorphism of PCR-SSCP was found in the 7th intron of the yak's insulin-like growth factor 2 gene, the result was detected that The polymorphism is controlled by a pare of allele A and B. The transition of C→T at 91 site of intron7 precipitated the replacement of B→A. Allele B and gene type BB were the superiority gene and gene type in Datong Yak , Qinghai plateau yak and Xinjiang yak. The disposition of gene type was consistent with Hardy-Weinberg balance. Gene type AB was the superiority gene type in the other two groups and the disposition of gene type was not balance.(2) The polymorphism of PCR-SSCP was found in the yak insulin-like growth factor 2, the result show that the transition of G→C at 330 site and A→G at 358 site of intron8 precipitated the replacement of B→A gene type BB and Allele B were the superiority gene type and superiority gene in all five groups. Only in Xinjiang Yak, the disposition of gene type was not balance, but they were balance in the other four groups.(3) IGF-Ⅱgene intron8 was close with the trait of body weight, the result of analysis showed that allele A has higher body weight than allele B. at the progress of animal breeding, IGF-Ⅱgene could be used by marker associate selection as a candidate gene of body weight. The body selected by allele A could enhance filial body weight.(4) The polymorphism of PCR-SSCP was found in the intron 11 of insulin-like growth factor receptor 2 gene, the result showed that the transition of T→C at 124 site and C→T at 172 site precipitated the replacement of B→A. Allele B was not found in Datong Yak, Gannan Yak and Xinjiang Yak. Though allele B was found at the other two groups, gene frequency is very low. The result of analysis showed that this site was not close with the traits of body weight, height, body length and chest girth.