摘要

目前预计纳米塑料碎片普遍存在于水生环境中，并且是一个新兴的环境问题，影响营养水平的生物。虽然摄取颗粒受到最多关注，但其他摄取途径和细胞积累仍未得到探索。在这里，浮游过滤器饲养器Daphnia magna用于跟踪聚苯乙烯纳米颗粒（PSNP）的摄取途径和靶组织。使用亚致死浓度的5mg L-1荧光PSNP（25nm）监测成年动物以及它们在开放的育雏袋中的胚胎的积累。育雏袋内胚胎发育过程中的时间序列揭示了胚胎发育早期的PSNP在亲脂细胞中或上的积累，而胚胎仍然被绒毛膜包围并且在器官发生开始之前。相反，PSNP颗粒既未在肠上皮中检测到，也未在成人中检测到脂滴中。胚胎向PSNP的离体暴露证明了PSNP在亲脂细胞中或上的类似积累，说明了胚胎摄取育雏袋介导的PSNP的可能性。通过育雏袋展示胚胎PSNP摄取，这里提供的数据给出了纳米粒子的生物累积和可能的其他亲脂性污染物的新见解。由于这种摄取途径可能发生在各种各样的水生生物中，因此本研究需要考虑育雏袋介导的积累，以研究纳米粒子污染的危害和风险。

Nanoplastic debris is currently expected to be ubiquitously distributed in aquatic environments and an emerging environmental issue affecting organisms across trophic levels. While ingestion of particles receives most attention, other routes of uptake and cellular accumulation remain unexplored. Here, the planktonic filter feeder Daphnia magna was used to track routes of uptake and target tissues of polystyrene nanoparticles (PSNPs). A sublethal concentration of 5 mg L-1 fluorescent PSNPs (25 nm) was used to monitor accumulation in adult animals as well as their embryos in the open brood pouch. A time series throughout embryonic development within the brood pouch revealed accumulation of PSNP in or on lipophilic cells in the early stages of embryonic development while the embryo is still surrounded by a chorion and before the beginning of organogenesis. In contrast, PSNP particles were neither detected in the gut epithelium nor in lipid droplets in adults. An ex vivo exposure of embryos to PSNP demonstrated a similar accumulation of PSNP in or on lipophilic cells, illustrating the likelihood of brood pouch-mediated PSNP uptake by embryos. By demonstrating embryo PSNP uptake via the brood pouch, data presented here give novel insights in bioaccumulation of nanoparticles and likely other lipophilic contaminants. Since this uptake route can occur within a diverse array of aquatic organisms, this study warrants consideration of brood pouch-mediated accumulation in efforts studying the hazards and risks of nanoparticle contamination.

https://www.ncbi.nlm.nih.gov/pubmed/29083253