East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China.
National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China.
Sci Total Environ. 2020 Nov 15;743:140754. doi: 10.1016/j.scitotenv.2020.140754. Epub 2020 Jul 8.
Harmful algal blooms (HABs) and thermal stress as climate changes become more common in global water ecosystem, especially under eutrophic habitats. Here our study examined the combined impacts of bloom forming cyanobacteria Microcystis aeruginosa and thermal stress on the antioxidant responses of the ecologically important species triangle sail mussel Hyriopsis cumingii. The differential responses of a series of enzymes, e.g. superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST), as well as signal metabolites including reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) involved in antioxidant defense mechanisms were analyzed during 14 d exposure to toxic cyanobacterium M. aeruginosa and 7 d depuration period. The activities of SOD and GPx as well as the content of ROS and MDA in H. cumingii increased, while CAT activity reduced due to M. aeruginosa exposure. Thermal stress resulted in decrease of CAT, the accumulation of GSH and the enhance of GST and SOD. Meanwhile, the interactive effects among M. aeruginosa, thermal stress and time were also observed on most parameters except for GST activity. The total amount of microcystins (MC) in sail mussels increased with concentrations of exposed M. aeruginosa, independently of the presence or absence of thermal stress. Although around 50% of MC in mussels dropped in the depuration period, most parameters showed alterations because of cyanobacteria exposure and thermal stress. Overall, these findings suggested that toxic cyanobacteria or thermal stress induces oxidative stress and severely affects the enzymes activities and intermediates level associated with antioxidant defense mechanisms in sail mussels respectively. More importantly, the toxic impacts on sail mussels could be intensified by their combination.
有害藻华（HABs）和热应激随着气候变化在全球水生态系统中变得越来越普遍，特别是在富营养化生境下。本研究探讨了形成水华的蓝藻铜绿微囊藻和热应激对生态重要物种三角帆蚌抗氧化反应的联合影响。在暴露于有毒蓝藻铜绿微囊藻和 7 天的净化期内，分析了一系列酶（如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）和谷胱甘肽-S-转移酶（GST））以及活性氧（ROS）、丙二醛（MDA）和谷胱甘肽（GSH）等信号代谢物的差异反应，这些代谢物参与抗氧化防御机制。铜绿微囊藻暴露导致三角帆蚌 SOD 和 GPx 活性以及 ROS 和 MDA 含量增加，而 CAT 活性降低。热应激导致 CAT 活性降低、GSH 积累增加以及 GST 和 SOD 活性增强。同时，除 GST 活性外，M. aeruginosa、热应激和时间之间的相互作用也在大多数参数中观察到。由于暴露于铜绿微囊藻，三角帆蚌体内的微囊藻毒素（MC）总量增加，而与是否存在热应激无关。尽管在净化期内，约有 50%的 MC 从贻贝中排出，但由于蓝藻暴露和热应激，大多数参数仍发生改变。总的来说，这些发现表明有毒蓝藻或热应激分别诱导氧化应激，并严重影响与抗氧化防御机制相关的酶活性和中间产物水平。更重要的是，它们的组合可能会加剧对贻贝的毒性影响。
