Wu Chao, Guo Wen-Bo, Liu Yue-Yue, Yang Liuyan, Miao Ai-Jun
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province, 210046, PR China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu Province, 210046, PR China.
J Hazard Mater. 2021 Feb 5;403:123923. doi: 10.1016/j.jhazmat.2020.123923. Epub 2020 Sep 12.
Microplastics (MPs) are an environmental hazard of growing concern, including their potential toxic effects on the biota of different trophic levels. Nevertheless, the molecular mechanisms underlying MP-induced toxicity remain largely unknown. In the present study, Tetrahymena thermophila was exposed to polystyrene nanoplastics (PS-NPs) and the responses of this relatively sensitive ciliate were then followed using transcriptome analysis together with several other verification methods. The results showed that PS-NPs perturbed calcium (Ca) homeostasis, by inducing the inositol-1,4,5-trisphosphate-dependent liberation of Ca from the endoplasmic reticulum into the cytosol. The high cytosolic concentration of Ca induced Ca accumulation in mitochondria, which increased mitochondrial permeability and the generation of reactive oxygen species, finally leading to growth inhibition. Such toxicity is the so-called direct effects of PS-NPs. By contrast, PS-NPs also inhibited the activity of multixenobiotic resistance transporter, by down-regulating the ATP-binding cassette transporter genes Abcb15 and Abcc52. This additional effect may alter cellular responses to other pollutants and implicates PS-NPs in the risks to the organism posed by subsequent toxic exposures, which was named as the indirect effects of PS-NPs. Our study highlights the importance of considering both direct and indirect biological effects of MPs in evaluations of their environmental and health risks.
微塑料（MPs）是一种日益引起关注的环境危害，包括其对不同营养级生物群的潜在毒性作用。然而，MPs诱导毒性的分子机制在很大程度上仍不清楚。在本研究中，嗜热四膜虫暴露于聚苯乙烯纳米塑料（PS-NPs），然后使用转录组分析以及其他几种验证方法跟踪这种相对敏感的纤毛虫的反应。结果表明，PS-NPs通过诱导肌醇-1,4,5-三磷酸依赖性的钙从内质网释放到细胞质中，扰乱了钙（Ca）稳态。细胞质中高浓度的钙诱导线粒体中钙的积累，这增加了线粒体通透性和活性氧的产生，最终导致生长抑制。这种毒性就是所谓的PS-NPs的直接效应。相比之下，PS-NPs还通过下调ATP结合盒转运蛋白基因Abcb15和Abcc52来抑制多药耐药转运蛋白的活性。这种额外的效应可能会改变细胞对其他污染物的反应，并使PS-NPs与后续毒性暴露对生物体造成的风险相关，这被称为PS-NPs的间接效应。我们的研究强调了在评估MPs的环境和健康风险时考虑其直接和间接生物学效应的重要性。
