Reversible inhibition of Chlamydomonas flagellar surface motility.

Abstract

Chlamydomonas exhibits force transduction in association with its flagellar surface; this can be visualized by the saltatory movements of attached polystyrene microspheres. This flagellar surface motility has been quantitated by determining the percentage of attached microspheres in motion at the time of observation (60% in the case of control cells at 25 degrees C). A number of experimental treatments reversibly inhibit flagellar surface motility. These include an increase in sodium or potassium chloride concentration, a decrease in temperature, or a decrease in the free calcium concentration in the medium. Many of the conditions that result in inhibition of flagellar surface motility also result in an induction of flagellar resorption. Although both flagellar stability and flagellar surface motility are dependent on the availability of calcium, the two processes are separable; under appropriate conditions, flagellar surface motility can occur at normal levels on flagella that are resorbing. Inhibition of protein synthesis results in a gradual loss of both the binding of microspheres to the flagellum and the flagellar surface motility. After resumption of protein synthesis, both binding and movement return to control levels. The effect of the inhibition of protein synthesis is interpreted in terms of selective turnover of certain components within the intact flagellum, one or more of these components being necessary for the binding of the microspheres and their subsequent movement. If this turnover is inhibited by keeping the cells below 5 degrees C, the absence of protein synthesis no longer has an effect on microsphere attachment and motility, when measured immediately after warming the cells to 25 degrees C.