Abstract:

Studying the function and mechanism of immune\|related genes can provide scientific reference for preventing and controlling diseases in sea cucumber (A. japonicus) culture. In this study, the full\|length cDNA of catalase gene from A. japonicus was cloned and characterized for the first time，which was 1 885 bp including a 76 bp 5′\|untranslated region (UTR), 1 503 bp ORF encoding 500 amino acids，and a 306 bp 3′\|UTR; and the predicted molecular weight was 56.56 kDa. The result of amino acid sequence alignment showed that 75% amino acid sequence identity to the Catalase of Hyriopsis cumingii and Strongylocentrotus purpuratus. The peroxisomal targeting signal PTS2, NADPH binding residues, and heme\|ligand binding signal sequences “RLFSYPDTH” were identified in the deduced amino acid sequence of Catalase from A. japonicus. Phylogenetic analysis suggested that the Catalase of A. japonicus was close to that of S. purpuratus in invertebrate cluster. Quantitative real\|time PCR analysis showed that catalase gene was expressed in all the tested tissues including body wall, feet, coelomocyte, respiratory tree, muscle, intestine, and the highest expression level was found in intestine. The expression of catalase mRNA was up\|regulated significantly in the coelomocytes at 4 h after LPS challenge. Those indicated that catalase gene was involved in the immune response to the bacteria challenge in A. japonicus.

Key words: sea cucumber (Apostichopus japonicus), catalase gene, LPS challenge

摘要：

研究仿刺参（Apostichopus japonicus）免疫相关基因的功能和作用机制可为仿刺参养殖病害的防控提供科学依据。克隆了仿刺参过氧化氢酶（catalase）基因的全长cDNA序列，全长1 885 bp，其中5′\|非翻译区（5′\|untranslated region，UTR）长76 bp，3′\|UTR长306 bp，开放阅读框（open reading frame，ORF）1 503 bp，编码500个氨基酸，预测蛋白分子量为56.56 kDa。氨基酸序列比对结果显示，仿刺参Catalase与三角帆蚌（Hyriopsis cumingii）和紫海胆（Strongylocentrotus purpuratus）的相似度最高，为75%。仿刺参catalase cDNA推导的氨基酸序列具有过氧化物酶定位信号PTS2、与还原型辅酶Ⅱ(NADPH) 结合的氨基酸残基及与其它物种高度保守的Catalase近端血红素配体签名序列（351RLFSYSDTH359）。系统进化分析显示仿刺参处于无脊椎动物分支中，和紫海胆位于同一小支上。实时定量PCR结果显示，catalase mRNA在仿刺参肠、体壁、肌肉、呼吸树、体腔细胞和管足中均有表达，在肠中表达量最高。在细菌脂多糖LPS刺激后4 h，体腔细胞中catalase mRNA表达量显著升高，表明仿刺参的catalase基因在应对外来病原菌刺激的免疫应答中发挥了重要作用。

关键词: 仿刺参；过氧化氢酶基因；LPS刺激