鸭凤头性状（Crest）致因突变位点鉴定与作用机制研究

The crest trait was characterized by a pinch of fuzz which was growing and forming the ornamental head crests overhead in ducks. Under the fuzz generally associated with sarcoma which can be used as packaging traits of high quality duck. And it was also found that the trait was closely related to cerebral hernia in other studies. Although this trait was dominant inheritance, the regulation of the formation and the molecular mechanism of this trait have not been elucidated clearly, which affected the process of utilization of the trait seriously. In the prophase of this study, we had tested the candidate genes of crested traits, such as Hoxc8 gene, EphB2 gene. Unfortunately, these two genes had no influence on this trait. Thus, we firstly intends to use whole genome resequencing technology to find the SNPs, InDels and Structural Variations which were related with crested traits. And then determine the position of the key candidate genes; identify the causal mutations of the trait. The Real -time quantitative PCR, fluorescent in situ hybridization（FISH）, Immunohistochemistry, or dual luciferase report system, EMSA technology were used to identify and verify the function of the causal mutations. At last, RCAS-Cr（MT） or transcription factor siRNA mediated crcr type embryo to detect the expression of Cr gene and phenotypic change over the head. This study will eventually reveal the formation and the genetic and molecular mechanism of the crested traits of the crested duck, and promote the process of conservation and utilization of the traits.

鸭凤头性状（Crest，Cr）因表型独特，具有较高的观赏价值，凤冠下伴生有肉瘤，更可作为优质肉鸭产业化急切需求的自身包装性状；研究发现该性状还与脑疝密切相关，亦可作为脑疝疾病的动物模型。虽该性状呈显性遗传趋势，但调控该性状形成的分子机理至今尚未阐明，严重影响了凤头性状的广泛利用。本课题组前期对候选基因Hoxc8、EphB2等进行了检测，发现均与该性状无关。因此本研究拟采用全基因组重测序技术找出与凤头性状相关的SNPs、InDels等变异信息，确定关键位置候选基因，鉴别因果突变位点，并利用qPCR、原位杂交、免疫组化或荧光素酶报告基因系统、EMSA对Cr基因编码区或调控区突变位点进行验证与功能鉴定，最后采用RCAS-Cr（MT）介导或转录因子siRNA介导crcr鸭胚，活体检测Cr基因的表达和表型变化。研究最终将揭示鸭凤头性状的形成与遗传分子机制，推进该性状的保护利用进程。

全世界鸭品种十分丰富，在长期人工选择过程中，形成了各种表型，如羽色、肤色、以及其他一些独特表型等性状。毛冠鸭就是一种表型突变类型。因其数量稀少，性状特殊，极具观赏价值，可为动物园、水景地、湿地公园增加景观、吸引游人提供素材。另外，毛冠性状（Crest，Cr）与脑疝紧密相关，进一步研究还发现，毛冠鸭颅内脂肪体的位置及大小与其运动协调性有关，毛冠鸭颅内脂肪体越大，小脑、大脑脚盖及嗅球就相对越小，其运动协调性就越差，常表现为共济失调。开展毛冠性状的研究，不仅有利于该性状的开发利用，还可为其他动物的脑疝研究提供一定的参考依据。本研究以毛冠鸭为试验材料， 对鸭凤头性状的遗传规律进行了分析，验证了凤头鸭的凤头性状呈常染色体显性遗传，且显性纯合致死，构建了10个凤头鸭（Crcr♂）×凤头鸭（Crcr♀）Cr基因分离家系，选取全同胞或半同胞F1共计8个个体进行全基因组重测序。获得320.32 G原始数据，平均的测序深度分别为43.89X、43.14X、45.93X、35.95X、43.23X、41.03X，获得了1739个关于SNP突变的基因和13 785关于InDel突变的基因，初步确定凤头的候选因果基因。验证了Hoxc8、EphA2、EphA3、EphB2等4个候选基因，其表达与凤头性状的形成有一定的相关性，Hoxc8可能是凤头性状形成重要的候选因果基因。研究过程中申请了“一种凤头白羽鸭的培育方法”的专利，每年制作凤头鸭3000只，使得凤头鸭这一珍稀资源得以恢复，形成了“观赏型”这种新的使用类型，填补了我国无观赏型鸭的空白。