鸡胡须性状的基因定位及功能研究

发布时间：2019-05-24 05:54

【摘要】：农业动物经历了上千年的自然选择和人工选择,积累了大量的表型变异。农业动物表型和遗传的多样性为我们提供了极好的研究模型,改善了我们对于动物发育和疾病发生等过程中基因功能的理解。羽毛是一种皮肤附属物,广泛分布于鸟类身体表面,具有各种各样的类型和变异,是解析调控羽毛发育与分化机制的重要资源。鸡的胡须(Muffs and beard, Mb)是一种在脸颊两侧(Muffs)以及颔下(Beard)着生的延长生长的羽毛类型,是一种单基因(Mb)控制的常染色体不完全显性性状。为了探究胡须性状形成的遗传学原因以及分子机制,本研究设计了以惠阳胡须鸡(Huiyang Bearded, HB)和岭南黄鸡A03系(High Quility chicken Line A, HQLA)为亲本的资源群体。其中,惠阳胡须鸡是我国重要的地方鸡种,特有的胡须性状使其成为研究羽毛区域特异性发育与分化的理想模型；岭南黄鸡A03系是广东省农业科学院畜牧研究所培育的快大型肉鸡品种,不具有胡须性状。本研究以此群体为基础,开展遗传定位研究工作,并对候选基因的表达及生物功能进行分析,试图从分子遗传学角度对胡须性状形成的机制进行阐述。本研究利用全基因组关联分析(Genome-wide association study, GWAS)、连锁分析(Linkage analysis)、同源相同(Identity by descent, IBD)分析、比较基因组杂交芯片(Array comparative genomic hybridization, array CGH)、全基因组重测序和表达分析等技术手段来研究引起胡须性状的致因基因。研究结果表明胡须性状是由27号染色体上复杂结构变异(Structural variation, SV)导致的,此结构变异由位于27号染色体上1.7 Mb、3.5 Mb以及4.4 Mb位置的三个拷贝数变异(Copy number variation, CNV)组成。三个CNV以串联的形式连接在一起,并插入1.7 Mb处CNV的下游。大量不同群体内的诊断分析验证了此复杂结构变异与胡须性状的完全关联。此复杂结构变异区间内共包含七个注释基因,对七个基因在胡须发育的不同阶段基因的表达情况进行检测,结果表明HOXB8基因在下颔皮肤组织中连续的异位高表达,强烈表明其在胡须性状发育过程中具有重要作用。本研究证明了鸡27号染色体上复杂的结构变异导致HOXB8基因的异位表达是鸡胡须性状形成的分子机制。这为复杂结构变异改变基因的表达模式进而产生表型突变提供了又一有力的证据。除此之外,本研究结果还揭示了HOXB8基因在调控羽毛区域特异性发育过程中的重要作用。
[Abstract]:Agricultural animals have experienced thousands of years of natural selection and artificial selection, and accumulated a large number of phenotypic variation. The phenotypic and genetic diversity of agricultural animals provides us with an excellent research model and improves our understanding of gene function during animal development and disease occurrence. Feather is a kind of skin appendage, which is widely distributed on the surface of birds and has a variety of types and variations. it is an important resource to analyze and regulate the mechanism of feather development and differentiation. Chicken beard (Muffs and beard, Mb) is a long-growing feather type that grows on both sides of the cheek (Muffs) and submandibular (Beard). It is an autosomal incomplete dominant trait controlled by single gene (Mb). In order to explore the genetic causes and molecular mechanism of beard traits, a resource population with Huiyang beard chicken (Huiyang Bearded, HB) and Lingnan yellow chicken line (High Quility chicken Line A, HQLA) as parents was designed in this study. Among them, Huiyang beard chicken is an important local chicken breed in China, and its unique beard traits make it an ideal model to study the regional specific development and differentiation of feathers. Lingnan yellow chicken A03 line is a fast large broiler breed cultivated by Animal Husbandry Research Institute of Guangdong Academy of Agricultural Sciences, which does not have beard traits. In this study, genetic mapping was carried out on the basis of population, and the expression and biological function of candidate genes were analyzed in order to elucidate the mechanism of beard traits formation from the point of view of molecular genetics. In this study, the whole genome association analysis (Genome-wide association study, GWAS), linkage analysis) (Linkage analysis), homologous (Identity by descent, IBD) analysis was used to compare the genomic hybrid chip (Array comparative genomic hybridization, array CGH),. The whole genome resequencing and expression analysis were used to study the etiogenic genes causing beard traits. The results showed that beard traits were caused by complex structural variation (Structural variation, SV) on chromosome 27, which was caused by 1.7 Mb, on chromosome 27. 3. 5 Mb and 4. 4 Mb position of the three copy number variation (Copy number variation, CNV) composition. The three CNV are connected in series and inserted downstream of CNV at 1.7 Mb. A large number of diagnostic analyses in different populations confirmed the complete correlation between this complex structural variation and beard traits. There were seven comment genes in this complex structural variation interval. The expression of seven genes in different stages of whisker development was detected. The results showed that HOXB8 gene was highly expressed in the skin tissue of chin. It strongly indicates that it plays an important role in the development of beard traits. This study proved that the ectopic expression of HOXB8 gene caused by complex structural variation on chicken chromosome 27 is the molecular mechanism of the formation of chicken beard traits. This provides another powerful evidence for complex structural variation to change the expression pattern of genes and then produce phenotypic mutations. In addition, the results of this study also reveal the important role of HOXB8 gene in regulating feather region-specific development.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S831

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