吉富罗非鱼IGF2基因分离及其单核苷酸多态性与体型、增重相关性

胰岛素样生长因子2(insulin-like growth factor2,IGF2)是控制动物生长和脂肪沉积的重要基因之一。本文采用PCR方法分离了吉富罗非鱼(GIFT strain Nile tilapia Oreochromis niloticus)IGF2基因5475bp,包含由4个外显子组成的整个阅读框669bp以及3个内含子。通过比对吉富罗非鱼10个个体IGF2序列,共发现11处单核苷酸多态性(single nucleotide polymorphism,SNP)位点,本文检测了内含子1的621nt(C/T)和外显子3的161nt(A/G)两位点在192尾吉富罗非鱼中的基因型分布,并分析不同基因型与体型、增重的相关性。使用四引物扩增受阻体系PCR检测内含子1的621nt基因型,结果显示,CC、CT、TT基因型频率在雄鱼中分别为0.32、0.32、0.36,在雌鱼中分别为0.38、0.38、0.24;与体型、增重的相关性分析表明,此位点不同基因型只与雄鱼体型(体高/体长)显著相关(P0.05),CC型个体显著高于CT和TT型个体。外显子3的A/G转换导致了MSPⅠ酶切位点改变,使用PCR-RFLP法检测该位点基因型,结果显示整个群体中不存在AA基因型,在雄鱼中,GG、AG基因型频率分别为0.71、0.29,而雌鱼中则为0.75和0.25;与体型、增重的相关性分析表明,此位点不同基因型只与雄鱼增重极显著相关(P0.01),GG型的雄鱼明显较AG型增重快。

Isolation of IGF2 Gene and Correlation of Its SNPs with Fish Sharp and Weight Gain in GIFT Strain Nile Tilapia Oreochromis niloticus

Insulin-like growth factor 2 gene was one of important genes controlling muscle growth and fat deposition in animals. In this study,we isolated 5 475 bp IGF2 including complete coding sequence 669 bp which interrupted by 3 introns and encoded 222 amino acids from GIFT strain Nile Tilapia Oreochromis niloticus. Total eleven SNPs were found at GIFT strain Nile Tilapia 0. niloticus IGF2 exons and introns through comparing sequences from 10 individuals. The genetypes of intron 1 621 nt and exon 3 161 nt were studied and the correlation of fish shape, weight gain with different genetypes were analyzed in this paper. Tetra-primers ARMS was performed to detect the SNP locus at 621 nt (C/T) of intron 1. The results indicated that the frequencies of CC, CT and TT were 0. 32,0. 32 and 0. 36 in male population, and 0. 38, 0. 38 and 0. 24 in female population respectively; there was only a remarkable correlation between different genotypes with male GIFT strain Nile tilapia O. niloticus body shape ( height/length) ( P < 0. 05 ) , CC individuals were significantly higher than CT and TT individuals. The SNP locus at 167 nt ( A/G) of exon3 was a nonsense mutation but it changed the restriction site of MSP I . So PCR-RFLP was used to detect the genotypes, only GG and AG individuals were found,with the frequencies of GG and AG 0. 71 and 0. 19 in male population and 0. 75 and 0. 25 in female population respectively; there was only a remarkable correlation between different genotypes with male GIFT strain Nile tilapia 0. niloticus weight gain ( P < 0. 01) , GG individuals were obviously higher than AG ones.