Analysis of Cell Vibration for Assessing Axonemal Motility in Chlamydomonas

Flagellar mutants of Chlamydomonas have greatly contributed to our understanding of the function of axonemes and axonemal dyneins. An important step in studying mutants is to correlate the molecular and structural defects in the axoneme with motility. This is not always easy, however, partly because it is often necessary to quantify axonemal motility by measuring the cellʹs swimming velocity, the flagellar beat frequency, or flagellar waveform in a number of cells or axonemes. To skip this timeconsuming step, a quick method for measuring the average flagellar beat frequency in a population of cells is developed based on fast Fourier transform (FFT) analysis of the vibration of cell bodies. This method yields the average beat frequency within 10–60 s and has been used as a powerful tool for identifying mutants lacking various dynein species. It is also particularly useful for studies analyzing detergent-extracted cell models under various reactivation conditions.