Calcium control of waveform in isolated flagellar axonemes of chlamydomonas

Abstract

The effect Ca++ of on the waveform of reactivated, isolated axonemes of Chlamydomonas flagella was investigated. Elagella were detached and isolated by the dibucaine procedure and demembranated by treatment with the detergent Nonidet; the resulting axonemes lack the flagellar membrane and basal bodies. In Ca++-buffered reactivation solutions containing 10 -4 M or less free Ca++, the axonemes beat with a highly asymmetrical, predominantly planar waveform that closely resembled that of in situ flagella of forward swimming cells. In solutions containing 10-4 M Ca++, the axonemes beat with a symmetrical waveform that was very similar to that of in situ flagella during backward swimming. In 10-4 M Ca++, the axonemes were predominantly quiescent, a state that appears to be closely associated with changes in axonemal waveform or direction of beat in many organisms. Experiments in which the concentrations of free Ca++ and the CaATP+ complex were independently varied suggested that free Ca++, not CaATP, was responsible for the observed changes. Analysis of the flagellar ATPases associated with the isolated axonemes and the Nonidet-soluble membrane-matrix fraction obtained during preparation of the axonemes showed that the axonemes lacked the 3.0S Ca++-activated ATPase, almost all of which was recovered in the membrane-matrix fraction. These results indicate that free Ca++ binds directly to an axonemal component to alter flagellar waveform, and that neither the 3.0S CaATPase nor the basal bodies are directly involved in this change. © 1980, Rockefeller University Press., All rights reserved.