College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, People's Republic of China.
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan, People's Republic of China.
J Fish Biol. 2023 May;102(5):1149-1156. doi: 10.1111/jfb.15366. Epub 2023 Mar 21.
The swamp eel, Monopterus albus, is an important aquaculture species in Asia (mainly China) whose production has seriously suffered from infectious diseases. In spite of the critical requirement for aquaculture practices, to date there is scant information on its immune defence. Here, the genetic characteristics of Toll-like receptor 9 (TLR9), which plays crucial roles in the initiation of host defence against microbial invasion, were analysed. It exhibits a striking lack of genetic variation resulting from a recent demographic bottleneck. A comparison with the homologue of M. javanensis revealed that replacement but not silent differences have nonrandomly accumulated in the coding sequences at the early stage following their split from a common ancestor. Furthermore, the replacements relevant to the type II functional divergence have mainly occurred in structural motifs mediating ligand recognition and receptor homodimerization. These results provide hints to understand the diversity-based strategy of TLR9 in the arms race against pathogens. Furthermore, the findings reported here give credence to the importance of basic immunology knowledge, especially for the key elements, in genetic engineering and breeding for disease resistance in the eel and other fishes.
白鳝，Monopterus albus，是亚洲（主要在中国）重要的水产养殖物种，其产量严重受到传染病的影响。尽管水产养殖实践存在重大需求，但迄今为止，有关其免疫防御的信息仍然很少。在这里，分析了 Toll 样受体 9（TLR9）的遗传特征，TLR9 在宿主防御微生物入侵的启动中起着至关重要的作用。它表现出由于最近的人口瓶颈而导致的惊人的遗传变异缺乏。与 M. javanensis 的同源物进行比较后发现，在它们从共同祖先分裂后，替代而不是沉默的差异已经在编码序列中随机积累。此外，与 II 型功能分歧相关的替代主要发生在介导配体识别和受体同源二聚化的结构基序中。这些结果为理解 TLR9 在与病原体的军备竞赛中基于多样性的策略提供了线索。此外，这里报道的发现证明了基础免疫学知识的重要性，特别是对于鳗鲡和其他鱼类的遗传工程和抗病性培育中的关键要素。
