Institute of Hydrobiology, Jinan University, Engineering Research Center of Tropical and Subtropical Aquatic Ecological Engineering Ministry of Education, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, West 601, Huangpu Avenue, Tianhe District, Guangzhou, 510632, People's Republic of China.
College of Animal Science, Southwest University Rongchang Campus, 160 Xueyuan Road, Rongchang District, Chongqing, 402460, People's Republic of China.
Fish Shellfish Immunol. 2019 Jan;84:865-875. doi: 10.1016/j.fsi.2018.10.083. Epub 2018 Oct 30.
The complement system plays an important role in protecting fish against attack by pathogens early in life. Complement component C3 is a central component in the complement system. The present work aimed to clone the full length C3 cDNA sequence of southern catfish (Silurus meridionalis), detect the tissue expression patterns of C3, investigate the ontogeny of C3 in embryo and larva, and assess the expression of C3 in response to pathogen infection. The full length C3 cDNA sequence of 5157 bp with an open reading frame (ORF) of 4938 bp was cloned from southern catfish. The deduced amino acid sequence showed similarity with other teleost fish. The mRNA expression of C3 was detected in liver, spleen, stomach, intestine, and head kidney with RT-PCR and in situ hybridization. Whole mount in situ hybridization results revealed that C3 was first expressed in the yolk syncytial layer at 34 h post fertilization (hpf), followed by the liver at 36 h post hatching (hph). When challenged with Aeromonas hydrophila, the transcripts of C3 showed a significant up-regulation in liver and spleen at 24 h. The results suggested that complement C3 played a key role in defense against invading pathogens in the early development stages of southern catfish. Therefore, these results provide important information to understand the functions of C3 during fish early development in Siluriformes.
补体系统在鱼类生命早期抵御病原体攻击方面起着重要作用。补体成分 C3 是补体系统的核心成分。本研究旨在克隆南方鲶（Silurus meridionalis）全长 C3 cDNA 序列，检测 C3 的组织表达模式，研究 C3 在胚胎和幼虫发育中的发生情况，并评估 C3 在应对病原体感染时的表达情况。从南方鲶中克隆出全长 5157bp 的 C3 cDNA 序列，其开放阅读框（ORF）为 4938bp。推导的氨基酸序列与其他硬骨鱼具有相似性。通过 RT-PCR 和原位杂交检测到 C3 在肝脏、脾脏、胃、肠和头肾中的 mRNA 表达。整体原位杂交结果显示，C3 首先在受精后 34 小时（hpf）的卵黄合胞层中表达，然后在孵化后 36 小时（hph）在肝脏中表达。当受到嗜水气单胞菌攻击时，肝脏和脾脏中 C3 的转录本在 24 小时时显著上调。结果表明，补体 C3 在南方鲶早期发育阶段抵御入侵病原体的过程中发挥了关键作用。因此，这些结果为了解 Siluriformes 鱼类早期发育过程中 C3 的功能提供了重要信息。
