Expression Pattern of IGF-I Gene and Correlation between Its SNPs and Growth Traits in Sheep

This study was to investigate the expression pattern of IGF-I gene and correlation between its SNPs and growth traits in sheep.The expression patterns of IGF-I gene in brain,muscle,skin,liver and heart of Liangshan semi-wool sheep were detected at six growth stages（15,60,105,195,240 days） by employing qRT-PCR approach,and the correlation between SNPs of IGF-I gene and growth traits via SSCP method.The first inflection point of IGF-I gene expression was observed at day 105 in all five tissues.From 15-105 days IGF-I gene gave a decline-ascending trend in muscle,brain and liver,while it did not vary significantly during day 15-day 60 and was up-regulated in heart and liver at day 105.Whenafter,the expression level was down-regulated in liver,while that in muscle,heart,brain and skin assumed the second inflection point.The expression levels of IGF-I gene in brain and skin at day 195 were significantly higher than that at day 150 and day 240.These suggest the synchronous expression of IGF-I gene in all five tissues.Two SNPs located at the leader region and exon 3 of IGF-I gene were middle or low polymorphic.The SNP locus detected with primer P-1 was significantly correlated with birth weight of Liangshan semi-wool sheep（P 〈0.05）,while that detected with primer P-2 was significantly correlated with weaning weight and the weaning daily gain（P 〈 0.05）.The expression of IGF-I in all tissues had the similar developmental patterns,and strong correlation of the SNPs of IGF-I gene was confirmed with the eary growth traits to provide theoretical basis for the growth regulation and applying to assisted selective breeding with the SNPs in liangshan semi-wool sheep.