Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sci Adv. 2024 Jul 5;10(27):eadn8356. doi: 10.1126/sciadv.adn8356.
Eukaryotic phytoplankton, also known as algae, form the basis of marine food webs and drive marine carbon sequestration. Algae must regulate their motility and gravitational sinking to balance access to light at the surface and nutrients in deeper layers. However, the regulation of gravitational sinking remains largely unknown, especially in motile species. Here, we quantify gravitational sinking velocities according to Stokes' law in diverse clades of unicellular marine microalgae to reveal the cell size, density, and nutrient dependency of sinking velocities. We identify a motile algal species, sp., that sinks faster when starved due to a photosynthesis-driven accumulation of carbohydrates and a loss of intracellular water, both of which increase cell density. Moreover, the regulation of cell sinking velocities is connected to proliferation and can respond to multiple nutrients. Overall, our work elucidates how cell size and density respond to environmental conditions to drive the vertical migration of motile algae.
真核浮游植物，又称藻类，是海洋食物网的基础，推动着海洋碳封存。藻类必须调节其运动和重力下沉，以平衡在表面获得光和在更深层获得营养物质的机会。然而，重力下沉的调节在很大程度上仍然未知，特别是在运动物种中。在这里，我们根据单细胞海洋微藻不同进化枝中的斯托克斯定律来量化重力下沉速度，以揭示下沉速度与细胞大小、密度和营养物质的依赖性。我们鉴定出一种运动藻类物种， sp.，由于光合作用驱动的碳水化合物积累和细胞内水分流失导致饥饿时下沉速度更快，这两者都会增加细胞密度。此外，细胞下沉速度的调节与增殖有关，并能对多种营养物质做出反应。总的来说，我们的工作阐明了细胞大小和密度如何响应环境条件来驱动运动藻类的垂直迁移。
