Pyramiding effect and preliminary verification of candidate genes for intramuscular fat traits in chickens | 鸡肌内脂肪性状候选基因的聚合效应及初步验证

Chinese. 目的旨在探讨影响鸡脂肪性状重要候选基因A-FABP、Ex-FABP的聚合效应，并对其进行初步验证，为进一步开发利用脂肪性状的有效分子标记提供依据。方法运用PCR-SSCP技术分别检测如皋鸡A-FABP、Ex-FABP基因所有外显子区域的单核苷酸多态性（SNPs），分析单基因型和聚合基因型与12周龄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单基因型和聚合基因型的发育性表达规律，进行聚合基因型遗传效应的初步验证。结果如皋鸡A-FABP的外显子3、Ex-FABP基因外显子4区域中存在A/G突变，共出现3种基因型；AA型(A-FABP)、BB（Ex-FABP）型个体的肌内脂肪含量显著高于其它基因型（P＜0.05），为有利基因型，两者聚合的AABB型个体同样为最佳基因型。经后代分离群体Q-PCR证实，单基因表达和聚合基因型的表达均不存在性别效应，在胸肌组织中，两候选基因在4周龄时表达量最高，8周龄下降，至12周龄缓慢上升。在聚合基因型个体中，均以AABB型表达水平最高，ABAB型表达量较低。结论A-FABP、Ex-FABP两个基因存在聚合效应；其中，AABB型与胸肌组织中高肌内脂肪含量具有紧密关联性。A-FABP、EX-FABP两基因及其聚合基因型可作为如皋鸡肌内脂肪性状有效的候选标记。

English. ObjectiveThis paper was designed to analyze the pyramiding effect and preliminary verification of A-FABP、Ex-FABP, which are the key candidate genes for intramuscular fat (IMF) traits in chickens, and to provide the basis of exploration and utilization of effective molecular markers on chicken fatty trait. MethodSingle nucleotide polymorphisms (SNPs) in all exons of Ex-FABP and A-FABP were detected with PCR-SSCP technology, and association between genotype and IMF content in breast muscle was conducted. Developmental expression pattern of singular and pyramiding genotypes in segregating progeny population were studied with fluorescence quantitative real-time PCR, and then preliminary verification of genetic effects of pyramiding genotypes were conducted.ResultThe results showed that, there is A/G mutation in exon 3 of A-FABP and exon 4 of Ex-FABP gene, respectively, and three genotypes were found totally. AA (A-FABP) and BB (Ex-FABP) were the dominant genotypes associated with high IMF content in breast muscle, and AABB was the dominant pyramiding genotype. The results of Q-PCR from segregating progeny population confirmed that there was no significant difference between male and female in expression pattern of two genes. In breast muscle, expression of two genes reached top point at 4 weeks old, decreased rapidly at 8 weeks old and rise slowly at 12 weeks old. Expression level of AABB genotype was the highest in all the pyramiding genotype individuals, and ABAB genotype was lowest, which was consistent with the results of singular genes’ expression and the difference in IMF contents. Thus, it proved that there was pyramiding effects in the two genes, and the AABB genotype had close association with the high IMF content in breast muscle.ConclusionA-FABP and Ex-FABP gene and their pyramiding genotype could be used as available candidate markers on IMF content trait in chicken.