Molecular mechanisms of the regulation of flagellar and cilliary movements.

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Takahashi showed that sliding velocities of sea urchin sperm flagellar axonemes, which were treated with elastase and reactivated at 100 muM ATP, were shown to be different in high and low calcium concentrations. Apparent sliding velocity of beating sea urchin sperm flagella was changed with changing the beat frequency, indicating that the sliding velocity is not determined with ATP concentration (Shingyoji). To study the molecular mechanism of motor proteins, Toyoshima has developed a novel in vitro motility assay system that allows us to hold motor proteins at specific site. Ogawa established to produce cDNA encoding the plausible dynein motor domain which is expressed in BaculoGold system. Kamiya isolated new Chlamydomonas mutants lacking different dynein heavy chains and thereby made clear their functions. Molecular shape of the outer arm dynein in flagella and cilia was surveyed among various animals by Mohri who showed the dynein in protists was three-headed, whereas that in other animals was two-headed. Electrophoretic analysis using chymotrypsin digestion has suggested that the alpha-tubulin isoform (a5) is located near dynein arms in Tetrahymena axonemes (Nakamura). According to Inaba, proteasomes are located at the projection extending from flagellar axoneme toward plasma membrance. Concerning the regulation of flagellar movements, Morisawa carried out purification of related proteins and then cDNA cloning in regard to the initiation, activation of sperm motility and chemotaxisof spermatozoa. Okuno demonstrated that the activation of mammalian sperm motility is tightry coupled with the changes in sliding velocity of microtubules, restaint between the microtubules and protein phosphorylation. Nakaoka showed that metachronal waves in ciliated cortical sheet of Paramecium was reconstituted in the reactivation medium containing cGMP.Cyclic AMP dependent phosphorylation of 29kDa and 65kDa were essential for controlling ciliary beating direction in Paramecium (