College of Fisheries, Guangdong Ocean University, Zhanjiang, Guangdong Province, PR China.
College of Fisheries, Guangdong Ocean University, Zhanjiang, Guangdong Province, PR China; Guangdong Provincial Engineering Laboratory for Mariculture Organism Breeding, Guangdong Ocean University, Zhanjiang, Guangdong Province, PR China.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111767. doi: 10.1016/j.ecoenv.2020.111767. Epub 2020 Dec 11.
Ammonia nitrogen and nitrite are two common forms of environmental toxicants for aquatic organisms including crustaceans. The PI3K-AKT pathway is an important intracellular signaling pathway related to cellular stress response, but involvement of this pathway in the immunotoxicological response of decapod crustaceans to aquatic toxicants such as ammonia nitrogen and nitrite still remains enigmatic. In this study, based on transcriptome mining and molecular cloning techniques, three key genes (named as MrPI3K, MrAKT and MrFoxO) in the PI3K-AKT signaling pathway were identified from the giant river prawn Macrobrachium rosenbergii. Sequence homology and phylogenetic analysis revealed that all the three genes harbored signature sequences of corresponding protein families, and shared high levels of similarities with their respective homologs from other species. MrPI3K, MrAKT and MrFoxO all displayed ubiquitous tissue distribution profiles, but their expression levels varied to a great extend among different tissues and between sexes. Following exposure to nitrite (20 mg/L nitrite-N) or ammonia (25 mg/L total ammonia-N) stresses for 24 h and 48 h, the three genes all responded by altering their expression levels at different time points, but they didn't show uniform expression patterns following these stresses, indicating the diversified roles of these genes in different tissues and the complexity of this signaling pathway. Remarkably, MrPI3K and MrAKT were induced only in the hemocytes and intestine, respectively, indicating their specific roles in these organs. Our study demonstrated the potential utility of these genes as biomarkers of acute ammonia or nitrite toxicity in prawns, and also provided evidence that the PI3K-AKT pathway is involved in the immunotoxicological responses to nitrite and ammonia stress in M. rosenbergii.
氨氮和亚硝酸盐是水生生物（包括甲壳类动物）的两种常见环境毒物形式。PI3K-AKT 通路是与细胞应激反应相关的重要细胞内信号通路，但该通路在甲壳类动物对氨氮和亚硝酸盐等水生毒物的免疫毒性反应中的作用仍然神秘莫测。在这项研究中，基于转录组挖掘和分子克隆技术，从罗氏沼虾（Macrobrachium rosenbergii）中鉴定出 PI3K-AKT 信号通路中的三个关键基因（命名为 MrPI3K、MrAKT 和 MrFoxO）。序列同源性和系统发育分析表明，这三个基因都具有相应蛋白家族的特征序列，与其他物种的相应同源物具有高度相似性。MrPI3K、MrAKT 和 MrFoxO 均显示出普遍的组织分布特征，但它们在不同组织和性别之间的表达水平存在很大差异。暴露于亚硝酸盐（20 mg/L 亚硝酸盐-N）或氨（25 mg/L 总氨-N）应激 24 h 和 48 h 后，这三个基因在不同时间点都通过改变其表达水平来响应，但它们在受到这些应激后没有表现出统一的表达模式，这表明这些基因在不同组织中的作用多样化，以及该信号通路的复杂性。值得注意的是，MrPI3K 和 MrAKT 分别仅在血细胞和肠中被诱导，表明它们在这些器官中的特定作用。我们的研究表明，这些基因可作为罗氏沼虾急性氨或亚硝酸盐毒性的生物标志物，并且还提供了证据表明 PI3K-AKT 通路参与了对亚硝酸盐和氨应激的免疫毒性反应。
