DataSheet_1_3D imaging shows nano- and microparticles are internalized by salmon skin and corneal epithelial cells.docx

The rising problem of plastic pollution is becoming one of the major environmental issues for the world. In the ocean, plastics undergo degradation into smaller microplastics (MPs) and nanoplastics (NPs). Wild fish and farmed salmon would likely be exposed to these NPs and MPs both through skin and through skin wounds. Keratocyte cells, located in the skin epithelial layer, are scavenger cells which may remove foreign materials and maintain the salmon’s health. They are therefore first in line to handle and to suffer from MP and NP exposure. While the impacts of MPs have been well studied in many different organisms, much less is known about the effects of NP exposure, particularly at the subcellular level. Here, we have used holotomographic and fluorescence microscopy to show that both skin and corneal salmon keratocyte cells fully internalize 500–1000 nm polystyrene particles, as well as inorganic 500 nm silica particles. The fact that corneal epithelial cells also take up particles is novel. Furthermore, some of these particles likely end up in lysosomal compartments within 2 hours of exposure. Here, we show that both conventional and new modalities of microscopy have a role to play to understand how micro- and nano particles affect epithelial cells.

塑料污染问题日益凸显，已成为全球环境问题中的关键议题之一。在大海中，塑料经过降解形成更小的微塑料（MPs）和纳米塑料（NPs）。野生鱼类和养殖鲑鱼可能会通过皮肤及其伤口接触到这些NPs和MPs。角化细胞，位于皮肤上皮层，是清除异物的吞噬细胞，并维持鲑鱼健康。因此，它们是首先处理和遭受MPs和NPs暴露影响的细胞。尽管MPs对许多不同生物体的影响已得到广泛研究，但关于NP暴露，尤其是在亚细胞水平上的影响，了解甚少。在本研究中，我们利用全息层析显微镜和荧光显微镜技术，展示了鲑鱼皮肤和角膜的角化细胞能够完全吸收500-1000纳米的聚苯乙烯颗粒，以及500纳米的无机二氧化硅颗粒。角膜上皮细胞也能吸收颗粒的事实具有创新性。此外，一些颗粒可能在暴露后2小时内进入溶酶体区室。在此，我们展示了传统和新型显微镜技术都在理解微纳米颗粒如何影响上皮细胞方面发挥着重要作用。