Qin Chuanjie, Shao Ting, Zhao Daxian, Duan Huiguo, Wen Zhengyong, Yuan Dengyue, Li Huatao, Qi Zemin
College of Life Science, Neijiang Normal University, Key Laboratory of Sichuan Province for Fishes Conservation and Utilization in the Upper Reaches of the Yangtze River, Neijiang 641000, PR China.
College of Life Science, Neijiang Normal University, Key Laboratory of Sichuan Province for Fishes Conservation and Utilization in the Upper Reaches of the Yangtze River, Neijiang 641000, PR China; College of Life Science, Sichuan Normal University, Chengdu 610101, PR China.
Fish Shellfish Immunol. 2017 Mar;62:107-115. doi: 10.1016/j.fsi.2016.12.031. Epub 2016 Dec 25.
The complement components C8α and C8β mediate the formation of the membrane attack complex (MAC) to resist pathogenic bacteria and play important roles in innate immunity. Full-length complement C8α (Pv-C8α) and C8β (Pv-C8β) cDNA were identified in the darkbarbel catfish Pelteobagrus vachellii, and their mRNA expression levels were analyzed after ammonia-N and pathogen treatment. The Pv-C8α gene contained 1983 bp, including a 1794-bp open reading frame (ORF) encoding 598 amino acids. The Pv-C8β gene contained 1952 bp, including a 1761-bp ORF encoding 587 amino acids. Pv-C8α and Pv-C8β had the highest amino acid identity with rainbow trout Oncorhynchus mykiss C8α (62%) and Japanese flounder Paralichthys olivaceus C8β (83%), respectively. Sequence analysis indicated that both Pv-C8α and Pv-C8β contained a thrombospondin type-1 (TSP1) domain, a low-density lipoprotein receptor class A (LDLR-A) domain, a membrane attack complex/perforin (MACPF) domain and an epidermal growth factor-like (EGF-like) domain. In addition, Pv-C8α and Pv-C8β were mainly distributed in the liver, head kidney, spleen, and eggs. Under ammonia-N stress, the Pv-C8α and Pv-C8β mRNA levels significantly decreased (P < 0.05), with minimum levels, respectively, attained at 24 and 48 h in the liver, 48 and 24 h in the head kidney, and 24 and 24 h in the spleen. After Aeromonas hydrophila challenge, the Pv-C8α and Pv-C8β mRNA levels significantly increased (P < 0.05), with maximum levels, respectively, attained at 48 and 24 h in the liver, 24 and 48 h in the head kidney, and 48 and 48 h in the spleen. The present study indicated that Pv-C8α and Pv-C8β exhibited important immune responses to infection and that ammonia-N in water decreased the immune responses of Pv-C8α and Pv-C8β.
补体成分C8α和C8β介导膜攻击复合物（MAC）的形成以抵抗病原菌，并在固有免疫中发挥重要作用。在暗纹东方鲀中鉴定出全长补体C8α（Pv - C8α）和C8β（Pv - C8β）cDNA，并分析了氨氮和病原体处理后它们的mRNA表达水平。Pv - C8α基因包含1983 bp，其中包括一个1794 bp的开放阅读框（ORF），编码598个氨基酸。Pv - C8β基因包含1952 bp，其中包括一个1761 bp的ORF，编码587个氨基酸。Pv - C8α和Pv - C8β分别与虹鳟鱼的C8α（62%）和牙鲆的C8β（83%）具有最高的氨基酸同一性。序列分析表明，Pv - C8α和Pv - C8β均包含一个血小板反应蛋白1型（TSP1）结构域、一个低密度脂蛋白受体A类（LDLR - A）结构域、一个膜攻击复合物/穿孔素（MACPF）结构域和一个表皮生长因子样（EGF样）结构域。此外，Pv - C8α和Pv - C8β主要分布在肝脏、头肾、脾脏和卵子中。在氨氮胁迫下，Pv - C8α和Pv - C8β的mRNA水平显著降低（P < 0.05），在肝脏中分别于24小时和48小时达到最低水平，在头肾中分别于48小时和24小时达到最低水平，在脾脏中分别于24小时和24小时达到最低水平。在嗜水气单胞菌攻击后，Pv - C8α和Pv - C8β的mRNA水平显著升高（P < 0.05），在肝脏中分别于48小时和24小时达到最高水平，在头肾中分别于24小时和48小时达到最高水平，在脾脏中分别于48小时和48小时达到最高水平。本研究表明，Pv - C8α和Pv - C8β对感染表现出重要的免疫反应，并且水中的氨氮会降低Pv - C8α和Pv - C8β的免疫反应。
