title: Generation of reactive oxygen species in cyanobacteria and green algae induced by allelochemicals of submerged macrophytes.
abstract: Inhibition of phytoplankton by allelochemicals released by submerged macrophytes is reported to be one of the mechanisms that maintain a clear-water state in shallow lakes. In order to elucidate this mechanism, the ability of six polyphenols and two long-chain fatty acids to induce the generation of reactive oxygen species (ROS) in phytoplankton was studied using the ROS sensitive probe 2',7'- dichlorodihydrofluorescein diacetate (DCFH-DA). The results showed that only (+)-catechin (CA) and pyrogallic acid (PA) could induce ROS formation in Microcystis aeruginosa and Pseudokirchneriella subcapitata. 25 mg L⁻¹ CA caused 1.2, 1.4 and 1.8 times increase of ROS levels in M. aeruginosa at 1, 2 and 4h exposure, respectively, and, correspondingly in P. subcapitata cells, these values were 3.7, 6.2 and 7.7, respectively. PA also significantly increased the levels of intracellular ROS in P. subcapitata (P < 0.01); however, significant ROS generation in M. aeruginosa was observed at only 4h exposure (P < 0.01). Light enhanced ROS generation in CA treated cells, but not in the cells treated with PA. CA and PA may act as redox cyclers after uptake by test organisms and produce ROS successively. These results suggest that the oxidative stress induced by the redox cycling property of allelochemicals may be one of the important causes for the inhibitory effect of some submerged macrophytes towards undesired phytoplankton in natural aquatic ecosystems.
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Junying
authors.initials: J
authors.lastname: Zhu
authors.forename: Shaoping
authors.initials: S
authors.lastname: Liu
authors.forename: Biyun
authors.initials: B
authors.lastname: Liu
authors.forename: Yunni
authors.initials: Y
authors.lastname: Gao
authors.forename: Zhenbin
authors.initials: Z
authors.lastname: Wu
mesh_terms: D059001:Aquatic Organisms / Q000737:chemistry*; D002392:Catechin / Q000302:isolation & purification / Q000494:pharmacology; D000460:Chlorophyta / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007101:Immersion; D019684:Magnoliopsida / Q000737:chemistry*; D058086:Microalgae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D046931:Microcystis / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010675:Pheromones / Q000302:isolation & purification / Q000494:pharmacology*; D011748:Pyrogallol / Q000302:isolation & purification / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015203:Reproducibility of Results
chemical_list: D010675:Pheromones; D017382:Reactive Oxygen Species; D011748:Pyrogallol; D002392:Catechin