Comparative growth and cellular responses of toxigenic Microcystis exposed to different types of microplastics at various doses
Comparative growth and cellular responses of toxigenic Microcystis exposed to different types of microplastics at various doses
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暴露于不同剂量的不同类型微塑料的产毒微囊藻的生长和细胞反应的比较
DOI：
10.1016/j.envpol.2021.117950
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发表时间：
2021
影响因子：
8.9
通讯作者：
Chen Yanran
中科院分区：
文献类型：
--
作者：
Wan Qianruo;Li Jieming;Chen Yanran
微塑料(MPS)污染经常与以微囊藻为主的淡水水华共存，但MPS对产毒微囊藻生长的影响及其作用机制尚不清楚。本研究以0.5μm-聚乙烯和聚氯乙烯为实验材料，在16天的实验中，探讨了单用和复合MPS对产毒微囊藻生长和细胞反应的剂量和时间依赖效应。结果表明，微囊藻的生长和细胞反应与暴露时间、MPS剂量和类型有关。MPS低剂量(5 mg/L)对小鼠早期有刺激作用，但在中后期随剂量的增加或PE+PVC剂量的增加而逐渐抑制生长，而在中后期剂量(5，10，50 mg/L)则逐渐减少，应激强度为PE+PVC>；进一步的分析表明，在MPS压力下，细胞损伤不明显，这主要是因为随着MPS压力的增加，抗氧化酶被越来越多地激活。中期单细胞MCs的释放能力与MPS胁迫下的总/结合量基本一致，每一组分的前多聚和前多聚前体量均有变化趋势。MPS胁迫下MCs释放能力与微囊藻中晚期的ex-Polyy/ex-Pro组分和细胞总数呈显著正相关，证实了MCs释放调控了ex-Polyy/ex-Pro的生成。此外，单细胞系膜细胞的产生能力与后期的可溶性、紧密结合和总的前多聚和前多聚原普遍呈正相关。提示微囊藻的细胞抗氧化剂、MCs的产生/释放能力和前多聚/前Pro的产生可能相互耦合，对MPS胁迫产生综合防御，从而保护微囊藻种群中的存活细胞。这些发现对于掌握微囊藻为主的水华与MPS污染共存的命运以及合理评估和管理所涉及的生态风险至关重要。
Microplastics (MPs) pollution frequently co-occur with Microcystis-dominated blooms in freshwaters, but MPs effects on toxigenic Microcystis growth and effect mechanisms remained poorly understood. This study used 0.5 μm-size polyethylene (PE) and polyvinyl chloride (PVC) to explore dose- and time-dependent effects of single and combined MPs (i.e., PE + PVC) on toxigenic Microcystis growth and cellular responses during 16 day-test. Results .showed that Microcystis growth and cellular responses depended on exposure time, MPs dose and type. MPs elicited hormesis effect in early stage at low dose (5 mg/L), while increasingly inhibited growth with rising PVC or PE + PVC dose but declining PE dose (5, 10, 50 mg/L) in mid-late stage, with stress intensity of PE + PVC > PVC > PE. Further analyses revealed unobvious cell damage under MPs stress, largely because antioxidases were increasingly activated as MPs stress enhanced. Unicellular MCs release ability during mid stage almost coincided with total/bound amount and each fraction of ex-poly and ex-pro trends under MPs stress. Significant positive relationship existed between MCs release ability and ex-poly/ex-pro fractions and total amount of Microcystis cells along mid-late stage under MPs stress, validating that ex-poly/ex-pro production was regulated as a result of .MCs release. Besides, unicellular MCs production ability was generally positively correlated with soluble, tightlybound and total ex-poly and ex-pro at late stage. These suggested that cellular antioxidants, MCs production/release ability and ex-poly/ex-pro production of Microcystis could be coupled to exert integrated defense against MPs stress to protect surviving cells in Microcystis population. These findings are crucial for acquiring the fate of Microcystis-dominated blooms co-occurring with MPs pollution, and reasonably assessing and managing involved eco-risks.