Bai Fang, Jia Yunlu, Li Jie, Wu Zhongxing, Li Lin, Song Lirong
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Ecotoxicol Environ Saf. 2023 Jan 1;249:114429. doi: 10.1016/j.ecoenv.2022.114429. Epub 2022 Dec 12.
Although programmed cell death (PCD) has been reported in phytoplankton, knowledge of the characterization of the PCD pathway and cascade process in different phytoplankton species is still limited. In this study, PCD progression in cyanobacterium Microcystis aeruginosa and green algae Chlorella luteoviridis by paraquat-induced oxidative stress was monitored. The results showed that paraquat-induced PCD in the two species belonged to the caspase-dependent pathway. Dose- and time-dependent PCD characteristics in the two strains under paraquat included the increase in caspase-like activity, DNA fragmentation, and chromatin condensation. However, the signaling pathway and cascade events of PCD in M. aeruginosa and C. luteoviridis differed. In M. aeruginosa, the free Ca concentration was rapidly increased at 8 h, followed by a significant elevation of the reactive oxygen species (ROS) level at 24 h, and eventual cell death. In C. luteoviridis, the mitochondrial apoptosis pathway, revealed by the depolarization of the mitochondrial membrane potential at 1 h and increase in the ROS level and caspase-like activity at 8 h, might contribute to cell death. In addition, the dynamics of ROS levels and metacaspase activity were synchronized, suggesting that paraquat-triggered PCD was ROS-mediated in both M. aeruginosa and C. luteoviridis. These results provide insights into PCD patterns in prokaryotic cyanobacteria and eukaryotic green algae under similar stress.
尽管在浮游植物中已报道了程序性细胞死亡（PCD），但对于不同浮游植物物种中PCD途径和级联过程的特征了解仍然有限。在本研究中，监测了百草枯诱导的氧化应激对蓝藻铜绿微囊藻和绿藻黄绿小球藻中PCD进程的影响。结果表明，百草枯诱导的这两个物种中的PCD属于半胱天冬酶依赖性途径。百草枯作用下，这两种菌株中PCD的剂量和时间依赖性特征包括类半胱天冬酶活性增加、DNA片段化和染色质浓缩。然而，铜绿微囊藻和黄绿小球藻中PCD的信号通路和级联事件有所不同。在铜绿微囊藻中，游离钙浓度在8小时迅速升高，随后在24小时活性氧（ROS）水平显著升高，最终导致细胞死亡。在黄绿小球藻中，1小时线粒体膜电位去极化以及8小时ROS水平和类半胱天冬酶活性增加所揭示的线粒体凋亡途径可能导致细胞死亡。此外，ROS水平和类半胱天冬酶活性的动态变化是同步的，表明百草枯触发的PCD在铜绿微囊藻和黄绿小球藻中均由ROS介导。这些结果为相似胁迫下原核蓝藻和真核绿藻中的PCD模式提供了见解。
