Abstract

A fine thread links the swimming of microscopic unicellular protozoa to the left-right asymmetry in our body plan. The connection is provided by the incessant beating of cilia and flagella, micrometre-size hair-like organelles highly conserved across eukaryotic species. From the wave-like beating patterns on the epithelium of our respiratory tract to the breaststroke beating in biflagellate algae, coordination in groups of cilia and flagella is often of paramount importance for their function. The remarkable similarity in the underlying molecular structure of flagella across the whole eukaryotic world leads naturally to the hypothesis that a similarly universal mechanism might be responsible for synchronisation. Although this mechanism is poorly understood, one appealing hypothesis is that it results from hydrodynamic interactions between flagella.

In this seminar I will discuss recent studies on flagellar dynamics in two species of green algae, the unicellular {\it Chlamydomonas reinhardtii} and the multicellular {\it Volvox carteri}, and will provide the strongest evidence yet for an elasto-hydrodynamic origin of flagellar synchronisation.