title: Cell-body rocking is a dominant mechanism for flagellar synchronization in a swimming alga.
abstract: The unicellular green alga Chlamydomonas swims with two flagella that can synchronize their beat. Synchronized beating is required to swim both fast and straight. A long-standing hypothesis proposes that synchronization of flagella results from hydrodynamic coupling, but the details are not understood. Here, we present realistic hydrodynamic computations and high-speed tracking experiments of swimming cells that show how a perturbation from the synchronized state causes rotational motion of the cell body. This rotation feeds back on the flagellar dynamics via hydrodynamic friction forces and rapidly restores the synchronized state in our theory. We calculate that this "cell-body rocking" provides the dominant contribution to synchronization in swimming cells, whereas direct hydrodynamic interactions between the flagella contribute negligibly. We experimentally confirmed the two-way coupling between flagellar beating and cell-body rocking predicted by our theory.
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
authors.forename: Veikko F
authors.initials: VF
authors.lastname: Geyer
authors.forename: Frank
authors.initials: F
authors.lastname: Jülicher
authors.forename: Jonathon
authors.initials: J
authors.lastname: Howard
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Friedrich
mesh_terms: D001696:Biomechanical Phenomena; D002696:Chlamydomonas / Q000502:physiology*; D005407:Flagella / Q000502:physiology*; D057446:Hydrodynamics; D008124:Locomotion / Q000502:physiology*; D018715:Microscopy, Video; D008954:Models, Biological
keywords: flagellar force–velocity relation; low-Reynolds-number hydrodynamics