本文選題：綠頭鴨 + 主要組織相容性復(fù)合體��； 參考：《浙江農(nóng)林大學》2016年碩士論文

【摘要】：綠頭鴨為我國家鴨的祖先之一,我國野生鴨類種群曾較為豐富,但由于過度獵取和生境條件改變,致使種群數(shù)量日趨減少。野生鴨類分布廣泛,大部分為遷徙性鳥類,是我國重要的經(jīng)濟鳥類。作為遷移性水禽的代表物種,綠頭鴨在病毒傳播過程中發(fā)揮著一定的作用。研究表明雁形目鳥類的病毒檢出率遠高于其他鳥類。主要組織相容性復(fù)合體(major histocompatibility complex,MHC)是廣泛存在于脊椎動物中并編碼免疫球蛋白樣受體的高度多態(tài)的基因群,其產(chǎn)物與免疫系統(tǒng)調(diào)節(jié),生長發(fā)育、生殖生理及衰老均密切關(guān)系,常作為功能性基因分子標記來研究遺傳多樣性和分析種群疾病抵抗能力。目前已證實相關(guān)物種中不同單倍型對流感病毒抗性存在差異。本研究以綠頭鴨為研究對象,通過cDNA確定MHC Ⅰ類分子的表達位點,利用RACE技術(shù)獲取表達位點的序列全長,并根據(jù)此設(shè)計MHC Ⅰ類分子抗原呈遞區(qū)(外顯子2和外顯子3)的單位點擴增引物,建立分位點擴增體系。并且對50只綠頭鴨進行MHC Ⅰ類表達位點的PCR-SSCP多態(tài)性分析,并進行分型,從而進行群體遺傳多樣性分析。結(jié)果表明綠頭鴨存在兩個MHC Ⅰ類表達位點,通過對多物種MHC Ⅰ類基因的氨基酸序列比對和聚類分析表明,綠頭鴨和鵝親緣關(guān)系最近,其次為雞。群體調(diào)查發(fā)現(xiàn)其外顯子2、外顯子3都具有很高的多態(tài)性,以顛換突變?yōu)橹鳌Ｍ怙@子2和外顯子3的GC含量分別為59.6%和51.2%,第三位密碼子位點的GC含量分別為89.7%和73.6%,這說明外顯子2受到的突變壓更大,這與外顯子結(jié)合抗原的功能有關(guān)。通過群體分析表明,MHC Ⅰ類基因的外顯子2和外顯子3位點均偏離哈文平衡(P0.05),外顯子2的PIC He Ne分別為0.460、3.784、0.68,外顯子3的PIC He Ne分別為0.460、3.211和0.635,三項數(shù)據(jù)表明綠頭鴨群體具有較高的遺傳多態(tài)性。本研究揭示了綠頭鴨種群MHC的遺傳多樣性,對于該物種的保護及遺傳育種的利用提供一定的理論基礎(chǔ)。
[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.
【學位授予單位】：浙江農(nóng)林大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：S865.3

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