School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, Shandong Province, 266109, China.
School of Marine Science and Engineering, Qingdao Agricultural University, Qingdao, Shandong Province, 266109, China.
Dev Comp Immunol. 2022 Jun;131:104394. doi: 10.1016/j.dci.2022.104394. Epub 2022 Mar 10.
Sebastes schlegelii (black rockfish) is a popular and economically important fish species in aquaculture. However, disease outbreaks have hindered the development of its cultivation. Antimicrobial peptides (AMPs) are a group of important components in fish innate immune system, that are active in the first line of defense against pathogens. The piscidin family, which are a group of fish-specific AMPs, have been isolated in a part of teleost but still poorly understood in S. schlegelii. In this study, three piscidin genes (Ss-piscidin1, 2, 3) are identified in S. schlegelii and their antibacterial activities and related mechanisms are analyzed. Three Ss-piscidins have conserved signal peptides but highly variable mature peptides and prodomains, and their mature regions all have predicted amphipathic and α-helical structures. Phylogenetic analysis shows that three Ss-piscidins cluster with different fish piscidin sequences into three sister clades, which correspond to three groups of fish piscidin family, respectively. Ss-piscidins have constitutive expressions in different tissues of healthy fish and enhanced expressions after Aeromonas salmonicida challenge. All three piscidins exhibit antibacterial activities, and are able to enhance bacterial membrane permeability and change bacterial morphology to different degrees, with a positive correlation observed among these activities. This suggests that three peptides exert their antibacterial activity through a "membrane-attack" mechanism. Moreover, hemolytic activities of three piscidins are also analyzed, and Ss-piscidin1, with low hemolytic ability and high antibacterial activity, is considered to be a possible candidate template for design of AMP drugs. Results in this study can promote a better understanding of immune responses in black rockfish and facilitate the future development of strategies in fish disease control in aquaculture.
黑鮶（Sebastes schlegelii）是水产养殖中一种受欢迎且具有重要经济价值的鱼类。然而，疾病的爆发阻碍了其养殖的发展。抗菌肽（AMPs）是鱼类先天免疫系统的重要组成部分，在抵御病原体的第一道防线中发挥作用。鱼杀菌肽家族是一组鱼类特异性的 AMPs，已在部分硬骨鱼中被分离出来，但在黑鮶中的了解仍很有限。本研究在黑鮶中鉴定了三个鱼杀菌肽基因（Ss-piscidin1、2、3），并分析了它们的抗菌活性及其相关机制。三个 Ss-piscidins 具有保守的信号肽，但成熟肽和前肽高度可变，其成熟区域均具有预测的两亲性和 α-螺旋结构。系统进化分析表明，三个 Ss-piscidins 与不同鱼类的鱼杀菌肽序列聚类为三个姐妹分支，分别对应于三个鱼类鱼杀菌肽家族组。Ss-piscidins 在健康鱼类的不同组织中均有组成型表达，在受到鲑鱼气单胞菌挑战后表达增强。三种鱼杀菌肽均具有抗菌活性，能够不同程度地增强细菌膜通透性并改变细菌形态，这些活性之间存在正相关关系。这表明三种肽通过“膜攻击”机制发挥其抗菌活性。此外，还分析了三种鱼杀菌肽的溶血活性，Ss-piscidin1 溶血能力低但抗菌活性高，被认为是设计 AMP 药物的潜在候选模板。本研究结果可以促进对黑鮶免疫反应的更好理解，并有助于未来在水产养殖中制定鱼类疾病控制策略。
