Basal coupling leads to coordinated beating of microfilaments

Cilia and flagella often beat in synchrony. More interestingly, they also switch between different synchronization modes. However, the biological and physical mechanisms responsible for such switching remain elusive. While experimental and theoretical evidence suggests that the phase coordination can be a result of hydrodynamical coupling, recent findings show that basal coupling plays an important role in such coordination. Here, we isolate hydrodynamic and basal coupling in a mathematical model of two microfilaments driven at their bases. To isolate basal from hydrodynamical coupling, we connect the microfilaments at their bases via an linear elastic spring and account for fluid drag using local resistive force theory. We find that the coordination of the filaments is strongly affected by the stiffness of the basal spring and the driving moment. Specifically, we observe a transition from in-phase to anti-phase coordination as the spring stiffness increases. We compare these results to synchronization via hydrodynamic interactions and comment on their relevance to understanding cilia coordination reported in experimental observations of algae cells such as \textit{Chlamydomonas}.