中文摘要：

近年来,在无颌类脊椎动物七鳃鳗体内发现了以可变淋巴细胞受体（Variable lymphocyte receptors,VLR）为基础的抗原识别机制。为揭示七鳃鳗鳃黏膜免疫系统中类淋巴细胞适应性免疫应答的遗传基础,探索无颌类与有颌类脊椎动物在适应性免疫应答机制上的进化关系,本文构建了日本七鳃鳗（Lampetra japonica）鳃囊组织免疫前后c DNA文库并进行了高通量转录组测序及分析。通过对组装得到的88 525个独立基因（Unigene）进行功能注释,分别有21 704和9769个unigene在GO（Gene Ontology）和KEGG（Kyoto Encyclopedia of Genes and Genomes）数据库得到注释。999个unigene参与免疫系统的多个通路,其中184个与高等脊椎动物TCR（T cell receptor）和BCR（B cell receptor）信号通路的51个分子具有较高的同源关系,说明七鳃鳗体内存在高等脊椎动物适应性免疫应答信号通路的相关分子。本文还发现5个VLRA、7个VLRB和4个VLRC分子,说明七鳃鳗鳃黏膜免疫组织内至少分布3种类淋巴细胞亚群。实时荧光定量PCR结果显示,Lck、Fyn和Zap70基因在免疫激发后表达量显著上调,而Syk、Btk和Blnk基因表达没有显著变化,说明七鳃鳗鳃组织受到抗原刺激后,类似T淋巴细胞的信号转导途径被激活。本研究初步证明,尽管无颌类和有颌类脊椎动物的适应性免疫系统在抗原识别机制上存在不同,但具有共同的遗传基础。研究结果为探讨七鳃鳗VLRA＋、VLRB＋和VLRC＋淋巴细胞免疫应答信号传导过程提供了有价值的线索。

英文摘要：

In recent years, the antigen recognition mechanism based on variable lymphocyte receptors（VLRs） was found in agnathan lamprey. To illuminate the genetic basis of immune response of lymphocyte-like cells in the mucosal immune system of lamprey and explore the evolutionary relationship of adaptive immune responses between the jawless and jawed vertebrates, we constructed c DNA libraries of lamprey（Lampetra japonica） gills before and after stimulation, and then performed high-throughput transcriptome sequencing and analysis. Through functional annotation of 88 525 assembled unigenes, 21 704 and 9769 unigenes were annotated in Gene Ontology（GO） and Kyto Encyclopedia of Genes and Genomes（KEGG） databases, respectively. Among 999 unigenes involved in multiple pathways of immune system, 184 unigenes were highly homologous to 51 TCR（T cell receptor） and BCR（B cell receptor） signalling molecules in higher vertebrates, indicating that molecules involved in adaptive immune signalling pathways in higher vertebrates also exist in lampreys. In addition, identification of five VLRA, seven VLRB and four VLRC molecules suggest that at least three types of lymphocyte subsets are distributed in lamprey gill mucosal immune tissues. The results of real-time fluorescence quantitative PCR showed that the expression levels of Lck, Fyn and Zap70 were up-regulated after immune stimulation while those of Syk, Btk and Blnk were not changed significantly, indicating the activation of TCR-like signal transduction pathway after antigen stimulation in lamprey gill tissues. Our studies preliminaryly proved that two parallel adaptive immune systems in jawless and jawed vertebrates have common genetic basis, and also provided valuable clues to the exploration of signalling processes of VLRA＋, VLRB＋, and VLRC＋ lymphocyte-like cells in response to antigens.