Abstract

Authors: K.Y. Wan & R.E. Goldstein. Many species of microorganisms such as bacteria, algae, and ciliates self-propel using slender, deformable structures known as cilia and flagella. Great variability exists in the number of flagella, their beating modes, and the basal architecture whence the flagella emanate. For instance, the model alga Chlamydomonas reinhardtii uses two near-identical flagella to pull itself through the fluid, executing a breaststroke. Meanwhile the little-known octoflagellate Pyramimonas octopus exhibits spontaneous switching between a small number of highly reproducible gaits. Here, we show how high resolution spatiotemporal visualisation and analysis of live cell locomotion may be used for behavioural stereotyping at the microscale, and furthermore to reveal the stochastic nature of flagellar beating. Quantitative distance and shape measures are deployed to delineate even subtle changes in behaviour, providing a means by which perturbations to cellular physiology are readily detected based on optical imaging alone.