摘要
胰岛素样生长因子 2在胎儿生长发育、肿瘤细胞增殖、肌肉生长等方面具有重要的调控作用 ,是影响猪瘦肉量的主要候选基因。采用PCR RFLP技术 ,分析了IGF2基因第 8内含子部分片段在猪资源家系群体中的NciⅠ酶切片段多态性分布。IGF2基因该片段具有两个NciⅠ酶切位点 (切点位于第 8内含子 ,分别记录为位点A和位点B) ,两位点在资源家系中均具有多态性。IGF2基因B位点酶切未突变个体均比酶切突变的个体背膘薄 18 2 8% (P<0 0 1) ,肥肉率低 2 2 4 3% (P <0 0 1) ,瘦肉率高 8 71% (P <0 0 1) ,位点A具有相同的影响趋势。在该研究群体中 ,IGF2基因发挥作用的方式主要为加性效应 。
Insulin like growth factor 2(IGF2)play an important role in fetal growth and development,tumour cell proliferation and muscle growth.IGF2 is the major candidate gene for affecting muscle mass in pig.Here we found a Nci Ⅰ PCR RFLP within intron 8 of the porcine IGF2 gene,and studied on effect of IGF2 gene on fat deposition.A fragment of 575 bp within intron 8 was obtained and digested with enzyme Nci Ⅰ.PCR RFLP analysis in a resource family of 173 pigs showed that there were two Nci Ⅰ restriction loci,which are locus A and B respectively in the fragment.To locus A ,single marker analysis showed that pigs with the IGF2 A2A2 genotype were 9 51% for shoulder fat thickness ( P <0 01),10 49% for 6th～7th rib fat thickness( P <0 01),11 46% for thorax waist fat thickness( P <0 05),19 32% for buttock fat thickness ( P <0 01) and 12 59% for average backfat thickness( P <0 01)less thick than pigs with the IGF2 A1A2 genotype.Significant differences for fat percentage and lean meat percentage between the IGF2 genotypes were also seen.Individuals of homozygote of restriction alleles had a significantly higher meat color for BF than individuals of heterozygote (4 23%, P <0 01).To locus B ,single marker analysis showed the same trend as on locus A .Individuals of homozygote of restriction alleles had a significantly less average fat thickness (18 82%, P <0 01),fat percentage (22 43%, P <0 01) and had more lean meat percentage (8 71%, P <0 01),meat color for BF (4 62%, P <0 05),water moisture (0 64%, P <0 01) than individuals of homozygote of mutation restriction allele in locus B.IGF2 gene showed mainly in the pattern of additive effect and all the dominant effect were not significant.The value of additive effect of average fat thickness,fat percentage and lean meat percentage was -0 20±0 05( P <0 01),-2 75±0 55 ( P <0 01),1 79±0 46( P <0 01),respectively.Significant correlation was found between IGF2 genotype and lean meat percentage.The result suggests that the IGF2 as a candidate gene can explain significant difference for fat deposit related traits in pig.
基金
国家"973"(编号 :G2 0 0 0 0 1610 5 )
"863"(编号 :2 0 0 1AA2 13 12 1)资助项目~~
