How Molecular Motors in Flagella Respond to Fluid Rheology

Many different microswimmers propel themselves using flagella, which are thin, threadlike filaments which beat in a periodic wavelike motion. The shape of the flagellar waveform emerges from the surrounding fluid interactions, which depends on the fluid rheology; from passive mechanical properties, like extensional and bending forces; and from active motor forces. It is thought that the mechanical feedback on the molecular dynein motor proteins in the flagella is responsible for the spatiotemporal coordination among motors. However, the means of mechanochemical feedback are not well understood, since the motor forces cannot be measured directly. We develop a computational model using experimental data of flagella in different types of fluids to extract information about how motor forces change in response to external forces and different fluid rheologies.