Department of Chemistry, Hong Kong Baptist University, 999077, Hong Kong, China; College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
Environ Int. 2024 Apr;186:108633. doi: 10.1016/j.envint.2024.108633. Epub 2024 Apr 4.
In the severe pollution area of nanoplastics (NPs) and cadmium ions (Cd), the joint effects of their high environmental concentrations on primary producers may differ from those of low environmental doses. Thus, we investigated the physiological changes, cell morphology, molecular dynamic simulation, phenotypic interactions, and metabolomics responses of C. pyrenoidosa to high environmental concentrations of NPs and Cd after 12-d acclimation. After 12-d cultivation, mono-NPs and mono-Cd reduced cell density and triggered antioxidant enzymes, extracellular polymeric substances (EPS) production, and cell aggregation to defend their unfavorable effects. Based on the molecular dynamic simulation, the chlorine atoms of the NPs and Cd had charge attraction with the nitrogen and phosphorus atoms in the choline and phosphate groups in the cell membrane, thereby NPs and Cd could adsorb on the cells to destroy them. In the joint exposure, NPs dominated the variations of ultrastructure and metabolomics and alleviated the toxicity of NPs and Cd. Due to its high environmental concentration, more NPs could compete with the microalgae for Cd and thicken cell walls, diminishing the Cd content and antioxidant enzymes of microalgae. NPs addition also decreased the EPS content, while the bound EPS with -CN bond was kept to detoxicate Cd. Metabolomics results showed that the NPs downregulated nucleotide, arachidonic acid, and tryptophan metabolisms, while the Cd showed an opposite trend. Compared with their respective exposures, metabolomics results found the changes in metabolic molecules, suggesting the NPs_Cd toxicity was mitigated by balancing nucleotide, arachidonic acid, tryptophan, and arginine and proline metabolisms. Consequently, this study provided new insights that simultaneous exposure to high environmental concentrations of NPs and Cd mitigated microalgae cellular toxicity, which may change their fates and biogeochemical cycles in aquatic systems.
在纳米塑料（NPs）和镉离子（Cd）的严重污染区域，其高环境浓度对初级生产者的联合影响可能与低环境剂量下的影响不同。因此，我们研究了 C. pyrenoidosa 在 12 天适应后对高环境浓度 NPs 和 Cd 的生理变化、细胞形态、分子动力学模拟、表型相互作用和代谢组学反应。经过 12 天的培养，单 NPs 和单 Cd 降低了细胞密度，并触发了抗氧化酶、细胞外多聚物（EPS）的产生和细胞聚集，以抵御不利影响。基于分子动力学模拟，NPs 和 Cd 的氯原子与细胞膜中胆碱和磷酸基团中的氮和磷原子具有电荷吸引力，因此 NPs 和 Cd 可以吸附在细胞上破坏它们。在联合暴露中，NPs 主导了超微结构和代谢组学的变化，并缓解了 NPs 和 Cd 的毒性。由于其高环境浓度，更多的 NPs 可以与微藻竞争 Cd 并加厚细胞壁，从而降低微藻的 Cd 含量和抗氧化酶。NPs 的添加还降低了 EPS 的含量，而与-CN 键结合的结合 EPS 则用于解毒 Cd。代谢组学结果表明，NPs 下调了核苷酸、花生四烯酸和色氨酸代谢，而 Cd 则呈现相反的趋势。与各自的暴露相比，代谢组学结果发现代谢分子发生了变化，这表明通过平衡核苷酸、花生四烯酸、色氨酸和精氨酸和脯氨酸代谢，NPs_Cd 毒性得到了缓解。因此，本研究提供了新的见解，即同时暴露于高环境浓度的 NPs 和 Cd 减轻了微藻细胞毒性，这可能改变它们在水生系统中的命运和生物地球化学循环。
