摘要
补体成分C9是构成膜攻击复合体引起靶细胞溶解破坏的重要组成成分。该文测定了香鱼C9 （aC9）基因的cDNA全序列, 序列全长2 125个核苷酸, 编码一个由592个氨基酸组成、相对分子质量为6.56×104的前体蛋白, N端22个氨基酸为信号肽序列。序列分析表明, aC9与虹鳟C9的氨基酸同源性最高, 达56.8%, 与其它鱼类C9的同源性介于40.9%~53.8%之间。aC9在健康香鱼肝、脾、肠、鳃和肌肉有表达, 其中在肝内的表达量最高。实时荧光定量PCR的结果显示, 鳗利斯顿氏菌侵染4 h后, 肝中aC9 mRNA表达量显著上调, 并随着时间的推移在16 h时达到峰值。Western blotting分析的结果显示, 鳗利斯顿氏菌侵染后香鱼血清中的aC9蛋白随着时间的推移呈显著上调。以上结果表明, 香鱼肝组织C9基因表达变化与鳗利斯顿氏菌的侵染密切相关,
C9, a component of the membrane attack complex, participates in the final stage of the complement cascade which lyses foreign organisms by disrupting the integrity of their cell membranes. In the present study, a full-length ayu C9 （aC9） cDNA was cloned which contains 2,125 nucleotides and encodes a protein of 592 amino acids. A signal peptide was deposited in the N-terminal 22 residues. The deduced amino acid sequence of aC9 showed 56.8% identity to the C9 of rainbow trout, and 40.9% to 53.8% identity to the C9 of other teleosts. RT-PCR analysis demonstrated that the mRNA ofaC9 was expressed in the liver, spleen, intestine, gill and muscle of healthy ayu fish with the highest level in the liver. Quantitative RT-PCR analysis showed that aC9 transcripts were significantly up-regnlated in the liver at 4 h post Listonella anguillarum infection, peaked at 16 h post injection. Western blotting analysis revealed that serum aC9 significantly increased in Listonella anguillarum infected ayu fish. Our results suggested that aC9 may play an important role in fish immune response of anti-bacteria.
基金
教育部新世纪优秀人才支持计划项目(NCET-08-0928)
宁波市自然科学基金项目(2010A610001)
