By building a biophysical model that incorporates real-world biological complexity, scientists discover important links between the nanometer-sized motors that power a cell’s cilia and the macroscopic fluid flows their collective beating creates.
Nearly 350 years ago, Dutch scientist Antonie van Leeuwenhoek peered into a vial of lake water through a self-made magnifying lens. Through this rudimentary microscope, he saw what he described as “animalcules with incredibly thin little feet that moved very nimbly.” The animalcules were a single-celled organism; the ‘feet’ were what we now call cilia: thousands of tiny, hairlike projections that oscillate on the surface of many cells, creating waves that can both propel the cell forward and move fluid past a stationary cell. Such motile cilia play important roles in the development and health of organisms: They create waves that pump fluid in the brain, for example, and help clear particles trapped in airways. Despite their importance, much remains unknown about the physics of how they function, especially collectively. A recently published study in the Proceedings of the National Academy of Sciences provides a new look at how ciliary waves come to be, by developing a model that incorporates the complex biology at work from the nanometer-sized motors that power cilia to the millimeter-scale waves the cilia create.
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