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Eukaryotic flagella beat rhythmically. Dynein is a protein that powers flagellar motion, and oscillation may be inherent to this protein. Here we determine whether oscillation is a property of dynein arms themselves or whether oscillation requires an intact axoneme, which is the central core of the flagellum and consists of a regular array of microtubules.(More)
The movement of eukaryotic flagella and cilia is regulated by intracellular calcium. We have tested a model in which the central pair of microtubules mediate the effect of Ca(2+) to modify the dynein activity. We used a novel microtubule sliding assay that allowed us to test the effect of Ca(2+) in the presence or absence of the central-pair microtubules.(More)
The changes in the bending pattern of flagella induced by an increased intracellular Ca(2+) concentration are caused by changes in the pattern and velocity of microtubule sliding. However, the mechanism by which Ca(2+) regulates microtubule sliding in flagella has been unclear. To elucidate it, we studied the effects of Ca(2+) on microtubule sliding in(More)
To help understand the mechanism by which the sliding movement of outer-doublet microtubules in cilia and flagella is converted into bending waves, we examined the effect of mechanical force imposed on the flagella of Chlamydomonas mutants lacking the central pair or multiple dyneins. These mutants were almost completely nonmotile under normal conditions. A(More)
It is generally accepted that the oscillatory beating characteristic of sperm flagella is the result of an ATP-induced sliding between the doublet microtubules of the flagellar axoneme, with these longitudinal forces being converted into a lateral bending moment by resistive components of the structure that limit the displacement. However, little is known(More)
Although eukaryotic flagella and cilia all share the basic 9+2 microtubule-organization of their internal axonemes, and are capable of generating bending-motion, the waveforms, amplitudes, and velocities of the bending-motions are quite diverse. To explore the structural basis of this functional diversity of flagella and cilia, we here compare the axonemal(More)
Dynein is a microtubule motor that powers motility of cilia and flagella. There is evidence that the relative sliding of the doublet microtubules is due to a conformational change in the motor domain that moves a microtubule bound to the end of an extension known as the stalk. A predominant model for the movement involves a rotation of the head domain, with(More)
The heads of live spermatozoa of the sea urchin Hemicentrotus pulcherrimus were held by suction in the tip of a micropipette mounted on a piezoelectric device and vibrated either laterally or axially with respect to the head axis. Within certain ranges of frequency and amplitude, lateral vibration of the pipette brought about a stable rhythmic beating of(More)