标题： 流体力学在{\it 衣藻}鞭毛同步中的作用 显示英文标题

标题： The role of hydrodynamics in the synchronisation of {\it Chlamydomonas} flagella

摘要： 虽然流体力学耦合长期以来被认为是真核鞭毛同步化的必要条件，但最近在单细胞双鞭毛模式生物{\it 衣藻}的实验表明，在单细胞水平上，细胞内机械耦合对于协调是必要的。 因此，目前尚不清楚流体力学力在单个细胞内多根鞭毛的同步化过程中究竟起到了什么作用，这可能是大规模协调的基本单元。 在这里，我们通过暂时阻断单个{\it 衣藻}的两根鞭毛之间的流体力学耦合来实验性地解决这个问题。 我们的结果显示，在野生型细胞中，由细胞内介导的作用力对于鞭毛的同步化是必要且充分的，而流体力学耦合对鞭毛动力学的影响微乎其微。 然而，在细胞内耦合力较弱的突变体中，流体介导的纤毛耦合负责了观察到的反相同步化延长现象。 因此，在单细胞水平上，鞭毛的协调依赖于细胞内和细胞外力之间微妙的平衡。 显示英文摘要

摘要： While hydrodynamic coupling has long been considered essential for synchronisation of eukaryotic flagella, recent experiments on the unicellular biflagellate model organism {\it Chlamydomonas} demonstrate that -- at the single cell level -- intracellular mechanical coupling is necessary for coordination. It is therefore unclear what role, if any, hydrodynamic forces actually play in the synchronisation of multiple flagella within individual cells, arguably the building block of large scale coordination. Here we address this question experimentally by transiently blocking hydrodynamic coupling between the two flagella of single {\it Chlamydomonas}. Our results reveal that in wild type cells intracellularly-mediated forces are necessary and sufficient for flagellar synchronisation, with hydrodynamic coupling causing minimal changes in flagellar dynamics. However, fluid-mediated ciliary coupling is responsible for the extended periods of anti-phase synchronisation observed in a mutant with weaker intracellular coupling. At the single-cell level, therefore, flagellar coordination depends on a subtle balance between intracellular and extracellular forces.