鸡A-FABP基因不同基因型遗传效应及初步验证

摘要

本研究旨在探讨影响鸡肌内脂肪性状的重要候选基因A-FABP的不同基因型遗传效应,并进行初步验证,为进一步开发利用脂肪性状的有效分子标记提供依据.运用PCR-SSCP技术检测如皋鸡A-FABP基因的单核苷酸多态性(SNPs),并分析其与胸肌脂肪含量之间的关系；同时采用荧光定量PCR技术检测后代分离群体不同基因型的时空表达规律,进行不同基因型遗传效应的初步验证.研究表明,如皋鸡A-FABP基因外显子3中1 763位点存在A/G突变,引起Ser(AA型)突变为Asn(BB型)；不同基因型对12周龄如皋鸡胸肌脂肪含量的关联分析发现,AA、AB基因型个体的IMF含量显著高于BB型个体(P＜0.05),AA型IMF含量最高,为有利基因型；经后代分离群体Q-PCR证实,A-FABP基因的表达不存在性别差异,在不同组织中表达量顺序:腹脂＞胸肌＞心脏＞肝脏；在不同时间阶段,肝脏、心脏和胸肌的表达趋势一致,4周龄时达到最高值,6～12周龄缓慢下降；而腹脂在10周龄时达到最高峰,12周龄开始下降.同一组织中不同基因型个体表达水平存在显著差异,BB基因型在所有组织中的表达量均处在较低水平,与肌内脂肪含量关联分析结果一致,从而表明BB型与低肌内脂肪含量具有紧密关联性.表明A-FABP基因外显子3中l 763位点变异可作为肌内脂肪性状有效的候选标记.%This experiment was designed to analyze and verify the genetic effect of different genotypes in adipocyte fatty acid-binding protein(A-FABP) gene, A-FABP was one of the important candidate genes for intramuscle fat trait (IMF) in chicken, which provided the base for explorat-ing and utilizating of molecular markers related to this trait. PCR-SSCP technology was used to detect the single nucleotide polymorphisms (SNPs) of A-FABP, and association between its SNPs and IMF content of breast muscle was conducted; then fluorescence quantitative real-time PCR was performed to explore the temporal and spatial expression pattern of different genotypes in progeny populations. A SNP (g. 1763 A>G) in exon3 of A-FABP gene was found, which resulted in the substitution of amino acid (Ser to Asn). In three genotypes of A-FABP gene, IMF contents of individuals with the AA and AB genotypes were significantly higher than that of individuals with the BB genotype (P<0. 05), and the AA genotype was the dominant. No significantly different expression was found between male and female. The expression level in differenttissues was abdominal fat, breast muscle, heart and liver according to the descending order. At different periods, the A-FABP expression had the same trend among muscle, heart and liver, which reached top point at 4 weeks and decreased from 6 weeks. However, A-FABP expressed in abdominal fat reached top point at 10 weeks and decreased from 12 weeks. In addition, the expression level had significant differences in the same tissue among the different A-FABP genotypes. The expression level of individuals with BB genotype was the lowest in all tissues, which was consistent with the results of association analysis between the detected SNPs and IMF content of breast muscle. Thus, the BB genotype had close association with the low IMF content of breast muscle in chicken. The results indicate that the mutation of g. 1763 A>G in exon 3 of A-FABP could be used as an available candidate marker affecting IMF content trait in chicken.