Mechanism and significance of generation of reactive oxygen by red tide plankton, Chattonella

滨Chattonella marina是一种鞭藻，是红潮中最具毒性的浮游植物之一，对鱼类，特别是对黄尾七尾藻有很高的毒性。虽然查顿菌中毒作用的确切机制尚不清楚，但已经证明，在接触查顿菌后，鱼类最早观察到的生理障碍是氧分压或动脉血的下降。对暴露于C.marina的鱼类进行的生理和组织学研究也表明，过多的粘液阻塞了通过鳃片的呼吸水流，干扰了氧气的转移，导致窒息。最近的研究表明，chatonella sp.产生活性氧（reactive oxygen species， ROS），如O2-、H2O2和羟基自由基（hydroxyl radical， OH）。此外，据报道，同样属于raphiophytic的Heterosigma akashiwo产生ROS，并对虹鳟鱼、Oncorhynchus等表现出氧自由基介导的毒性作用。因此，ROS的产生很可能是raphiophycean鞭毛虫的共同特征。我们最近的研究结果支持了这一观点，即其他raphiophysi类鞭毛虫如Olisthodiscus luteus和Fibrocapsa japonica产生o2和H2O2。因为氧自由基的有害影响已被充分证明。查顿菌产生的活性氧可能是造成鳃组织损伤的原因。有趣的是，最近的研究结果表明，chatonella产生ROS是由Con A、CBH和WGH等凝集素刺激的，这表明细胞表面氧化还原酶可能参与了o2的产生，这种酶负责凝集素的刺激。此外，从黄尾鱼、红鲷鱼和日本比目鱼的皮肤和鳃中制备的鱼粘液刺激C.marina和h.b akashiwo产生的o2量以浓度依赖的方式增加。这些结果表明，鱼粘液增强了ROS介导的查顿菌对鱼的毒性作用。少

Chattonella marina, a raphidophycean flagellate, is one of the most noxious red tide phytoplankton and is highly toxic to fish, especially to yellowtail Seriola quinqueradiata. Although the precise mechanism of the toxic action or Chattonella sp.remains unclear, it has been demonstrated that a decrease in oxygen partial pressure or arterial blood is the earliest physiological disturbance observed in fish after exposure to C.marina. Physiological and histological studies of fish exposed to C.marina also suggested that the blockade of respiratory water flow through the gill lamellae caused by excessive mucus interferes with O2 transfer, resulting in asphyxia. Recent studies have shown that Chattonella sp.generates reactive oxygen species (ROS) such as O2-, H2O2, and hydroxyl radical (OH). Furthermore, it has been reported that Heterosigma akashiwo, which is also classified in a raphidophycean, produces ROS,and showed an oxygen-radical-mediated toxic effect on rainbow trout, Oncorhynchus … More mykiss. Thus, it is likely that the production of ROS is a common feature of raphidophycean flagellates. This notion is supported by our recent findings in which other raphidophycean flagellates such as Olisthodiscus luteus and Fibrocapsa japonica produce O2-and H2O2. Since harmful effects or oxygen radicals have been well documented. ROS generated by Chattonella sp.may be responsible for gill tissue injury. Interestingly, resent results domonstrated that the generation of ROS by Chattonella is stimulated by lectins such as Con A,CBH,and WGH,suggesting that cell-surface redox enzyme may be involved in O2-production, and such enzyme is responsible for the lectin-stimulation. Furthermore, Fish mucus prepared from skin and gill of yellowtail, red sea bream, and japanese flounder stimulated C.marina and H.akashiwo to generate increased amounts or O2-in a concentration dependent manner. These results suggest that fish mucus enhances the ROS mediated toxic effects of Chattonella against fish. Less