The rheological properties of eukaryotic cilia and flagella

[Cod. PID2019-104232GB-I00 RheoFlag]

Cilia and flagella are slender organelles common to a wide spectrum of eukaryotes, both marine and terrestrial. Their deformations -either passive or active- underpin essential processes, from mechanical sensing and locomotion of aquatic microorganisms, to the generation of feeding currents in corals. Autonomous ciliary beating is particularly important. It stems from the coupling between passive properties of the internal structure of the flagellum and the activity of hundreds of molecular motors within it. The detailed mechanism leading to beating, however, is currently not well understood. To progress, it is critical to have first a precise grasp of the visco-elastic properties of the axoneme. So far, experiments have only probed static elasticity.

This project aims to use an active-rheology approach to measure directly both viscous and elastic components of flagellar mechanics, developing the required experimental and data analysis techniques, and leading to an improved, experimentally-tested model of the axoneme. Flagellar elongation will be used here as a tool to differentiate between flagellar and basal-body viscoelasticity. The results will critically advance our understanding of axonemal biomechanics, flagellar coupling to intracellular cytoskeleton, and provide a new avenue to investigate the biomechanical role of individual axonemal protein species. In turn, this will be crucial to the development of models of flagellar activity, with impact on microbial locomotion and beyond.