绿头鸭MHCⅠ类基因遗传多样性研究

发布时间：2018-06-26 08:15

本文选题：绿头鸭 + 主要组织相容性复合体　；参考：《浙江农林大学》2016年硕士论文

【摘要】：绿头鸭为我国家鸭的祖先之一,我国野生鸭类种群曾较为丰富,但由于过度猎取和生境条件改变,致使种群数量日趋减少。野生鸭类分布广泛,大部分为迁徙性鸟类,是我国重要的经济鸟类。作为迁移性水禽的代表物种,绿头鸭在病毒传播过程中发挥着一定的作用。研究表明雁形目鸟类的病毒检出率远高于其他鸟类。主要组织相容性复合体(major histocompatibility complex,MHC)是广泛存在于脊椎动物中并编码免疫球蛋白样受体的高度多态的基因群,其产物与免疫系统调节,生长发育、生殖生理及衰老均密切关系,常作为功能性基因分子标记来研究遗传多样性和分析种群疾病抵抗能力。目前已证实相关物种中不同单倍型对流感病毒抗性存在差异。本研究以绿头鸭为研究对象,通过cDNA确定MHC Ⅰ类分子的表达位点,利用RACE技术获取表达位点的序列全长,并根据此设计MHC Ⅰ类分子抗原呈递区(外显子2和外显子3)的单位点扩增引物,建立分位点扩增体系。并且对50只绿头鸭进行MHC Ⅰ类表达位点的PCR-SSCP多态性分析,并进行分型,从而进行群体遗传多样性分析。结果表明绿头鸭存在两个MHC Ⅰ类表达位点,通过对多物种MHC Ⅰ类基因的氨基酸序列比对和聚类分析表明,绿头鸭和鹅亲缘关系最近,其次为鸡。群体调查发现其外显子2、外显子3都具有很高的多态性,以颠换突变为主。外显子2和外显子3的GC含量分别为59.6%和51.2%,第三位密码子位点的GC含量分别为89.7%和73.6%,这说明外显子2受到的突变压更大,这与外显子结合抗原的功能有关。通过群体分析表明,MHC Ⅰ类基因的外显子2和外显子3位点均偏离哈文平衡(P0.05),外显子2的PIC He Ne分别为0.460、3.784、0.68,外显子3的PIC He Ne分别为0.460、3.211和0.635,三项数据表明绿头鸭群体具有较高的遗传多态性。本研究揭示了绿头鸭种群MHC的遗传多样性,对于该物种的保护及遗传育种的利用提供一定的理论基础。
[Abstract]:Mallard duck is one of the ancestors of domestic ducks in China. The wild duck population was abundant in China, but the population decreased gradually because of overhunting and changing habitat conditions. Wild ducks, most of which are migratory birds, are important economic birds in China. As a representative species of migratory waterfowl, mallard plays a role in the transmission of the virus. Studies have shown that the detection rate of wild geese is much higher than that of other birds. The major histocompatibility complex (major histocompatibility) is a highly polymorphic gene group that encodes immunoglobulin-like receptors in vertebrates. Its products are closely related to the regulation of immune system, growth and development, reproductive physiology and aging. It is often used as a functional gene molecular marker to study genetic diversity and to analyze population disease resistance. It has been confirmed that different haplotypes have different resistance to influenza virus in related species. In this study, the expression sites of MHC class I molecules were determined by cDNA, and the full length of the expressed sites was obtained by race technique. According to this, the primer amplification of unit site of MHC class I antigen presentation region (exon 2 and exon 3) was designed, and the system of locus amplification was established. PCR-SSCP polymorphism analysis of MHC class I expression loci was carried out in 50 mallard ducks, and the population genetic diversity was analyzed. The results showed that there were two MHC class I expression loci in mallard duck. The amino acid sequence alignment and cluster analysis of MHC class I gene in many species showed that the relationship between mallard duck and goose was the closest, followed by chicken. It was found that exon 2 and exon 3 were highly polymorphic, mainly transversion mutation. The GC contents of exon 2 and exon 3 were 59.6% and 51.2%, respectively, and the GC contents of the third codon were 89.7% and 73.6%, respectively, which indicated that exon 2 was subject to higher mutation pressure, which was related to the function of exon binding antigen. Population analysis showed that exon 2 and exon 3 of MHC class I gene deviated from the Haven equilibrium (P0.05). The PIC he ne of exon 2 was 0.460 ~ 3.784 ~ 0.68, and the PIC he ne of exon 3 was 0.460 ~ 3.211 and 0.635, respectively. Three data showed that the PIC he ne of mallard duck population was 0.635. It has high genetic polymorphism. This study revealed the genetic diversity of MHC in mallard duck population and provided a theoretical basis for the conservation and utilization of MHC in Mallard duck population.
【学位授予单位】：浙江农林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S865.3

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