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Analysis of Flagellar Gait Changes Across Fluid Viscosities: From Shapes to Motor Models
Mathematical Biology| Speaker: | Kelli Gutierrez, UC Davis |
| Location: | 2112 MSB |
| Start time: | Wed, May 13 2026, 10:00AM |
Description
Many microswimmers propel themselves using flagella, which are thin, threadlike filaments that beat in a periodic wavelike motion. The flagellar beat emerges from the coupled interactions between the surrounding fluid and the active and passive responses of the flagellum. Previous studies have observed qualitative waveform changes with varying fluid rheology. It is thought that this spatiotemporal coordination among motors is due to mechanical feedback on dynein motors. However, the mechanisms of mechanochemical feedback are not well understood, since the motor forces cannot be measured directly. In this study, we explore the effects of fluid viscosity on the flagellar waveforms of Chlamydomonas reinhardtii swimming in Newtonian fluids. First, we quantify changes in the flagellar waveforms in response to varying fluid viscosity, using (i) shape mode analysis on a dataset of ten cells swimming in fluids with different viscosities, and (ii) a full swimmer simulation to analyze how shape changes affect the swimming speed and to explore the dimensionality of the shape space. The time-independent mean shape changes substantially in response to viscosity, while the changes in the time-varying stroke are more subtle. Second, we develop a computational model that couples a molecular motor model with a nonlinear swimming simulation to examine how motor forces respond to external loading. Although these motor models have been shown to qualitatively reproduce the Chlamydomonas reinhardtii waveform, we find that they do not reproduce the beat frequency or beat asymmetry observed in our dataset.
*** This is Kelli's GGAM PhD Exit Seminar. ***
Also on zoom https://ucdavis.zoom.us/j/98969645841