CCAAT/enhancer binding protein alpha gene (CEBPA) plays an important role in lipogenesis,growth,and development,and sine oculis homeobox homolog 1 gene (Six1) plays a regulatory role in skeletal muscle development and muscle fiber type transformation,and both of the two genes are closely related to bone development.The single nucleotide polymorphisms (SNPs) of the exons of CEBPA gene and Six1 gene were detected by direct sequencing in this study.The purpose of this study was to uncover the effects of CEBPA gene and Six1 gene on the carcass traits and body size traits of Wuliang Mountain black-bone chicken (Gallus gallus).The results showed that three SNPs (i.e.74 C＞G,552 G＞A and 936 C＞T) were found in CEBPA gene,and two SNPs (i.e.375 G＞A and 564 G＞A) were found in Six1 gene.All SNPs except two SNPs (i.e.936 C＞T of CEBPA gene and 375 G＞A of Six1 gene) exhibited three genotypes,and the predominant alleles were non-mutation allele.The chi-square test showed that allelic frequency and genotype frequency of two SNPs (i.e.552 G＞A of CEBPA gene and 564 G＞A of Six1 gene) didn't agree with the Hardy-Weinberg equilibrium (P＞0.05),while others did.As for polymorphic information content,all SNPs were in a low polymorphism.The mutation (C→G) of 74 bp in CEBPA gene caused the change of amino acids (i.e.Threonine → Serine),while others didn't.Moreover,there was no strong linkage disequilibrium(LD)among each gene's respective SNPs.In the group of Wuliang Mountain black-bone chicken,5 haplotypes and 7 diplotypes were formed on CEBPA gene,and 4 haplotypes and 5 diplotypes were formed on Six 1 gene.Association studies of genotypes of SNPs and diplotypes with carcass traits and body size traits were performed by using the GLM.The results showed that four SNPs (i.e.74 C＞G and 936 C＞T of CEBPA gene,375 G＞A and 564 G＞A of Six1 gene) were significantly or highly correlated with carcass traits and body size traits (P＜0.05 or P＜0.01).74 C＞G of CEBPA gene was significantly correlated with the percentage of half-eviscerated yield,the percentage of eviscerated yield,body slope length,breast width,breast depth and fossil bone length (P＜0.05).936 C＞T of CEBPA gene was significantly correlated with live weight,dressed weight,half-eviscerated weight,eviscerated weight,breast muscle weight,body slope length,pelvis width and shank length (P＜0.05 or P＜0.01).The percentage of half-eviscerated yield and eviscerated yield of diplotype H1H1 and H4H4,breast muscle weight,pelvis width and shank length of diplotype H1H2,body slope length of diplotype H1H4 and H4H4,breast width,breast depth and fossil bone length of diplotype H4H4 were significantly higher than other partial diplotypes,respectively (P＜0.05 or P＜0.01).375 G＞A of Six1 gene was significantly correlated with breast depth and pelvis width (P＜0.05 or P＜0.01),while it was not significantly associated with carcass traits.564 G＞A of Six1 gene was significantly correlated with breast muscle weight,the percentage of breast muscle,breast angel,shank length and shank circumference (P＜0.05 or P＜0.01).The breast muscle weight and the percentage of breast muscle of H6H6,H6H7 and H6H8 diplotypes,dressed percentage of H6H7 diplotype,eviscerated weight,breast depth and pelvis of H6H8 diplotype,breast angel,shank length and shank circumference of H7H7 diplotype were significantly higher than other partial diplotypes,respectively (P＜0.05 or P＜0.01).The present research suggested that CEBPA gene and Six1 gene had significant genotype effects on the carcass traits and body size traits of Wuliang Mountain black-bone chicken and could be potential candidate genes for molecular marker-aid selection in Wuliang Mountain black-bone chicken and other chicken breeds.%CCAAT/增强子结合蛋白α基因(CCAAT/enhancer binding protein alpha gene,CEBPA)在脂肪生成、生长发育过程中发挥重要作用,同源异型基因Six1(sine oculis homeobox homolog 1 gene)在骨骼肌的发育和肌纤维类型的转化中起调控作用,且两者均与骨骼的发育密切相关.本研究以CEBPA和Six1基因为候选基因,采用直接测序法检测2个基因外显子的单核苷酸多态性(single nucleotide polymorphisms,SNPs),并分析其对无量山乌骨鸡(Gallus gallus)屠体和体尺性状的影响.研究结果表明,在CEBPA基因外显子上共检测到74C＞G、552 G＞A、936 C＞T 3个突变位点,在Six1基因外显子上共检测到375 G＞A和564G＞A2个突变位点,其中只有CEBPA基因74 C＞G位点的突变引起了氨基酸的变化,且为中性突变.连锁不平衡(linkage disequilibrium,LD)分析发现,CEBPA基因的各突变位点间、Six1基因的各突变位点间均不存在强连锁不平衡.在无量山乌骨鸡群体中,CEBPA基因的3个SNPs位点形成了5种单倍型和7种双倍型,Six1基因的2个SNPs位点形成了4种单倍型和5种双倍型.关联分析表明,CEBPA基因的74 C＞G突变位点对半净膛率、全净膛率、体斜长、胸宽、胸深和龙骨长有显著或极显著影响(P＜0.05或P＜0.01),936 C＞T突变位点对活重、屠体重、半净膛重、全净膛重、胸肌重、体斜长、骨盆宽和胫长有显著或极显著影响(P＜ 0.05或P＜0.01).双倍型H1H1、H4H4的半净膛率、全净膛率,H1H2的胸肌重、骨盆宽、胫长,H1H4和H4H4的体斜长,H4H4的胸宽、胸深、龙骨长分别显著高于其他部分双倍型(P＜0.05或P＜0.01);Six1基因的375 G＞A和564 G＞A突变位点对部分屠体和体尺性状有显著性影响(P＜ 0.05或P＜0.01),双倍型H6H6、H6H7、H6H8的胸肌重、胸肌率,H6H7的屠宰率,H6H8的全净膛重、胸深、骨盆宽,H7H7的胸角、胫长、胫围,分别显著高于其他部分双倍型(P＜0.05或P＜0.01).本研究结果表明,CEBPA基因和Six1基因的多态性对无量山乌骨鸡的屠体和体尺性状有显著影响,可作为无量山乌骨鸡及其他鸡种屠体和体尺性状分子标记辅助性选择的候选基因.
展开▼
