The widespread presence of microplastics (MPs) in freshwater systems has raised concerns about their potential ecotoxicity to aquatic organisms. In this study, we evaluated the effects of four MPs with different compositions, namely polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC) and polypropylene (PP), on freshwater microalgae Chlamydomonas reinhardtii. PS and PVC MPs caused greater growth inhibition and stronger oxidative stress responses than PP and PE MPs. Proteomics analysis was employed to explore the mechanical understanding of the composition-dependent toxicity of MPs to microalgae. Proteins involved in photosynthesis processes were identified as contributors to the diverse responses of microalgae to differently composed MPs. The photosynthesis activity of algae, including the pigment content and photoprotective response, was determined to reflect the distinct effect of the four MPs. The indicated down-regulated expression of photosynthetic proteins by proteomics analysis was further confirmed using a western blot assay, with PVC and PS showing greater impacts on their expression reduction. Our findings not only show the composition-dependent effect of MPs on microalgae but also provide important insights into the molecular mechanism of MPs' toxicity to natural phytoplankton species.

中文翻译：

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微塑料对淡水微藻莱茵衣藻成分依赖性影响的蛋白质组学见解


淡水系统中广泛存在的微塑料（MP）引起了人们对其对水生生物潜在生态毒性的担忧。在这项研究中，我们评估了四种不同成分的MP，即聚乙烯（PE）、聚苯乙烯（PS）、聚氯乙烯（PVC）和聚丙烯（PP）对淡水微藻莱茵衣藻的影响。 PS 和 PVC MP 比 PP 和 PE MP 引起更大的生长抑制和更强的氧化应激反应。采用蛋白质组学分析来探索 MP 对微藻的成分依赖性毒性的机械理解。参与光合作用过程的蛋白质被确定为微藻对不同组成的 MP 的不同反应的贡献者。确定藻类的光合作用活性，包括色素含量和光保护响应，以反映四种 MP 的独特效果。蛋白质组学分析表明光合蛋白的表达下调，并通过蛋白质印迹测定进一步证实，PVC和PS对其表达降低的影响更大。我们的研究结果不仅显示了 MP 对微藻的成分依赖性影响，而且还为 MP 对天然浮游植物物种毒性的分子机制提供了重要见解。