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A trigger mechanism of herbicides to phytoplankton blooms: From the standpoint of hormesis involving cytochrome b559, reactive oxygen species and nitric oxide.
Water Research ( IF 11.4 ) Pub Date : 2020-02-04 , DOI: 10.1016/j.watres.2020.115584
Yueheng Zhang 1 , Edward J Calabrese 2 , Junyi Zhang 3 , Dan Gao 1 , Mengnan Qin 1 , Zhifen Lin 4
Affiliation  

The cause of phytoplankton blooms has been extensively discussed and largely attributed to favorable external conditions such as nitrogen/phosphorus resources, pH and temperature. Here from the standpoint of hormesis response, we propose that phytoplankton blooms are initiated by stimulatory effects of low concentrations of herbicides as environmental contaminants spread over estuaries and lakes. The experimental results revealed general stimulations by herbicides on Microcystis aeruginosa and Selenastrum capricornutum, with the maximum stimulation in the 30-60% range, depending on the agent and experiment. In parallel with enhancing stimulation, the ratio of HP (high-potential) form to LP (low-potential) form of cytochrome b559 (RHL) was observed decreasing, while intracellular reactive oxygen species (ROS) were observed increasing. We propose that the ROS originated from the thermodynamic transformation of cytochrome b559, enhancing the stimulatory response. Furthermore, the results also proved that thermodynamic states of cytochrome b559 could be modulated by nitric oxide, thus affecting cellular equilibrium of oxidative stress (OS) and correspondingly causing the inhibitory effect of higher concentrations of herbicides on phytoplankton. This suggests that hormesis substantially derives from equilibrium shifting of OS. Moreover, it is reasonable to infer that phytoplankton blooms would be motivated by herbicides or other environmental pollutants. This study provides a new thought into global phytoplankton blooms from a contaminant perspective.

中文翻译:

除草剂引发浮游植物开花的触发机制:从涉及细胞色素b559,活性氧和一氧化氮的兴奋作用的角度出发。

浮游植物开花的原因已被广泛讨论,并且很大程度上归因于有利的外部条件,例如氮/磷资源,pH和温度。在这里,从兴奋剂反应的角度出发,我们认为浮游植物的开花是由低浓度除草剂的刺激作用引起的,这是由于环境污染物在河口和湖泊中扩散所致。实验结果表明,除草剂对铜绿微囊藻和七叶忍冬的总体刺激作用最大,在30-60%的范围内,具体取决于药剂和实验。在增强刺激的同时,观察到细胞色素b559(RHL)的HP(高电势)形式与LP(低电势)形式的比率降低,而细胞内活性氧(ROS)则增加。我们建议ROS起源于细胞色素b559的热力学转化,从而增强刺激反应。此外,结果还证明一氧化氮可以调节细胞色素b559的热力学状态,从而影响细胞氧化应激(OS)的平衡,并相应地引起较高浓度的除草剂对浮游植物的抑制作用。这表明,兴奋作用主要来自OS的平衡移动。此外,有理由推断,浮游植物的开花是由除草剂或其他环境污染物引起的。这项研究从污染物的角度为全球浮游植物的开花提供了新思路。结果还证明一氧化氮可以调节细胞色素b559的热力学状态,从而影响细胞氧化应激(OS)的平衡,并相应地引起较高浓度的除草剂对浮游植物的抑制作用。这表明,兴奋作用主要来自OS的平衡移动。此外,有理由推断,浮游植物的开花是由除草剂或其他环境污染物引起的。这项研究从污染物的角度为全球浮游植物的开花提供了新思路。结果还证明一氧化氮可以调节细胞色素b559的热力学状态,从而影响细胞氧化应激(OS)的平衡,并相应地引起较高浓度的除草剂对浮游植物的抑制作用。这表明,兴奋作用主要来自OS的平衡移动。此外,有理由推断,浮游植物的开花是由除草剂或其他环境污染物引起的。这项研究从污染物的角度为全球浮游植物的开花提供了新思路。这表明,兴奋剂主要来自OS的平衡移动。此外,有理由推断,浮游植物的开花是由除草剂或其他环境污染物引起的。这项研究从污染物的角度为全球浮游植物的开花提供了新思路。这表明,兴奋作用主要来自OS的平衡移动。此外,有理由推断,浮游植物的开花是由除草剂或其他环境污染物引起的。这项研究从污染物的角度为全球浮游植物的开花提供了新思路。
更新日期:2020-02-04
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