Polystyrene microplastics alleviate the developmental toxicity of silver nanoparticles in embryo-larval zebrafish (Danio rerio) at the transcriptomic level

Since silver nanoparticles (AgNPs) and polystyrene microplastics (PS-MP) share common environmental niches, their interactions can modulate their hazard impacts. Herein, we assessed the developmental toxicity of 1 mg/L PS-MP, 0.5 mg/L AgNPs and the mixtures of AgNPs and PS-MP on embryo-larval zebrafish. We found that AgNPs co-exposure with PS-MP remarkably decreased mortality rates, malformation rates, heart rates and yolk sac area, while it increased hatching rates and eye size compared to the AgNPs group. These phenomena revealed that the cell cycle, oxidative stress, apoptosis, lipid metabolism, ferroptosis and p53 signalling pathway were obviously affected by single AgNPs exposure at 96 hpf (hours post fertilization). Interestingly, all these effects were effectively ameliorated by co-exposure with PS-MP. The combination of transcriptomic and metabolomic analyses showed that the imbalance of DEGs (differentially expressed genes) and DEMs (differentially expressed metabolites) (PI, phosphatidylinositol and TAG-FA, triacylglycerol-fatty acid) disturbed both the cell cycle and lipid metabolism following single AgNPs exposure and co-exposure with PS-MP. These findings suggest that PS-MP attenuates the developmental toxicity of AgNPs on embryo-larval zebrafish. Overall, this study provides important insight into understanding the transcriptional responses and mechanisms of AgNPs alone or in combination with PS-MPs on embryo-larval zebrafish, providing a reference for ecological risk assessment of combined exposure to PS-MP and metal nanoparticles.