Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy.
Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy.
Environ Pollut. 2019 Nov;254(Pt A):112947. doi: 10.1016/j.envpol.2019.07.115. Epub 2019 Aug 4.
One of the current main challenges faced by the scientific community is concerning the fate and toxicity of plastics, due to both the well-known threats made by larger plastic items spreading in ecosystems and their fragmentation into micro- and nanoparticles. Since the chemical and physical characteristics of these smaller plastic fragments are markedly different with respect to their bulk product, the potential toxicological effects in the environment need to be deeply investigated. To partially fill this gap of knowledge, the aim of this study was to evaluate the polystyrene nanobead intake in the tissues of zebrafish (Danio rerio) embryos and their related toxicity. Embryos at 72 h post fertilization (hpf) were exposed for 48 h to 0.5 μm fluorescent polystyrene nanobeads at a concentration of 1 mg L. Confocal microscopy was employed to investigate nanoplastic ingestion and tissue infiltration, while potential sub-lethal effects were evaluated by measuring several endpoints, which covered the adverse effects at the molecular (protein carbonylation), cellular (P-glycoprotein, activity of several antioxidant/detoxifying enzymes) and organism levels by evaluating of possible changes in the embryos' swimming behaviour. Imaging observations clearly highlighted the nanoplastics' uptake, showing nanobeads not only in the digestive tract, but also migrating to other tissues through the gut epithelium. Biomarker analyses revealed a significant decrease in cyclooxygenase activity and an induction of superoxide dismutase. The behavioural test highlighted a significant (p < 0.05) variation in the turn angle between the control and exposed embryos. This study points out the capability of nanoplastics to infiltrate zebrafish embryo tissues, even after a short exposure, thus suggesting the need for deeper investigations following longer exposure times, and highlighting the potential of nanoplastics to cause toxicological effects on freshwater organisms, at the organism level.
科学界目前面临的主要挑战之一是塑料的命运和毒性，这不仅是因为较大的塑料物品在生态系统中扩散以及它们破碎成微塑料和纳米颗粒所带来的众所周知的威胁，还因为这些较小的塑料碎片的化学和物理特性与它们的块状产品明显不同，因此需要深入研究其在环境中的潜在毒理学效应。为了部分填补这一知识空白，本研究旨在评估聚碳酸酯纳米珠在斑马鱼（Danio rerio）胚胎组织中的摄入及其相关毒性。受精后 72 小时（hpf）的胚胎在浓度为 1mg/L 的 0.5μm 荧光聚苯乙烯纳米珠中暴露 48 小时。共聚焦显微镜用于研究纳米塑料的摄入和组织渗透，同时通过测量几个终点来评估潜在的亚致死效应，这些终点涵盖了分子水平（蛋白质羰基化）、细胞水平（P-糖蛋白、几种抗氧化/解毒酶的活性）和机体水平（通过评估胚胎游泳行为的可能变化）的不良反应。成像观察清楚地强调了纳米塑料的摄取，表明纳米珠不仅存在于消化道中，而且通过肠上皮迁移到其他组织中。生物标志物分析显示环加氧酶活性显著降低，超氧化物歧化酶活性升高。行为测试突出显示控制组和暴露组胚胎之间的转弯角度有显著变化（p<0.05）。本研究表明纳米塑料能够渗透斑马鱼胚胎组织，即使在短时间暴露后也是如此，因此建议在更长时间暴露后进行更深入的研究，并强调纳米塑料在机体水平上对淡水生物产生毒理学效应的潜力。
