Marine Biology Department, Centre Scientifique de Monaco, Monaco, Monaco.
Elife. 2020 Feb 10;9:e50022. doi: 10.7554/eLife.50022.
Transport of fluids, molecules, nutrients or nanoparticles through coral tissues are poorly documented. Here, we followed the flow of various tracers from the external seawater to within the cells of all tissues in living animals. After entering the general coelenteric cavity, we show that nanoparticles disperse throughout the tissues via the paracellular pathway. Then, the ubiquitous entry gate to within the cells' cytoplasm is macropinocytosis. Most cells form large vesicles of 350-600 nm in diameter at their apical side, continuously internalizing their surrounding medium. Macropinocytosis was confirmed using specific inhibitors of PI3K and actin polymerization. Nanoparticle internalization dynamics is size dependent and differs between tissues. Furthermore, we reveal that macropinocytosis is likely a major endocytic pathway in other anthozoan species. The fact that nearly all cells of an animal are continuously soaking in the environment challenges many aspects of the classical physiology viewpoints acquired from the study of bilaterians.
流体、分子、营养物质或纳米颗粒通过珊瑚组织的运输情况鲜有记录。在这里，我们在活体动物的所有组织中追踪了各种示踪剂从外部海水进入细胞内的过程。在进入一般的腔肠腔后，我们发现纳米颗粒通过细胞旁途径在组织中扩散。然后，普遍存在的进入细胞细胞质的入口是巨胞饮作用。大多数细胞在其顶端形成直径为 350-600nm 的大囊泡，不断内化周围的介质。使用 PI3K 和肌动蛋白聚合的特异性抑制剂证实了巨胞饮作用的存在。纳米颗粒的内化动力学与尺寸有关，并且在不同组织之间存在差异。此外，我们揭示了巨胞饮作用可能是其他珊瑚动物物种的主要内吞途径。事实上，动物的几乎所有细胞都在不断地浸泡在环境中，这挑战了从扁形动物研究中获得的经典生理学观点的许多方面。
