Coordinated Beating of Algal Flagella is Mediated by Basal Coupling
Wan, Kirsty Y
Proceedings of the National Academy of Sciences (PNAS)
National Academy of Sciences
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Wan, K. Y., & Goldstein, R. (2016). Coordinated Beating of Algal Flagella is Mediated by Basal Coupling. Proceedings of the National Academy of Sciences (PNAS) https://www.repository.cam.ac.uk/handle/1810/255058
Cilia and flagella often exhibit synchronized behavior; this includes phase-locking, as seen in Chlamydomonas, and metachronal wave formation in the respiratory cilia of higher organisms. Since the observations by Gray and Rothschild of phase synchrony of nearby swimming spermatozoa, it has been a working hypothesis that synchrony arises from hydrodynamic interactions between beating filaments. Recent work on the dynamics of physically separated pairs of flagella isolated from the multicellular alga Volvox has shown that hydrodynamic coupling alone is sufficient to produce synchrony. However, the situation is more complex in unicellular organisms bearing few flagella. We show that flagella of Chlamydomonas mutants deficient in filamentary connections between basal bodies display markedly different synchronization from the wildtype. We perform micromanipulation on configurations of flagella and conclude that a mechanism, internal to the cell, must provide an additional flagellar coupling. In naturally-occurring species with 4, 8 or even 16 flagella, we find diverse symmetries of basal-body positioning and of the flagellar apparatus that are coincident with specific gaits of flagellar actuation, suggesting that it is a competition between intracellular coupling and hydrodynamic interactions that ultimately determines the precise form of flagellar coordination in unicellular algae.
Chlorophyte, Prasinophyte, eukaryotic algae, internal coupling, flagellar synchronization, basal fibers
This work is supported by a Junior Research Fellowship from Magdalene College Cambridge (KYW) and a Wellcome Trust Senior Investigator Award (REG). We thank Kyriacos Leptos and Marco Polin for discussions relating to the contractility of the basal apparatus at an early stage of this work, and the possible insights provided by the vfl class of mutants, Francois Peaudecerf for kindly providing the CR gametes, Matthew Herron, Thomas Proschold and Stephanie Hohn for valuable comments on the manuscript.
Wellcome Trust (097855/Z/11/Z)
This record's URL: https://www.repository.cam.ac.uk/handle/1810/255058