Studies on control of ciliary activity in triton-extracted models of schistosome miracidia

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The study was designed to explore the mechanism(s) of control of activity of cilia which are present all over the surface of schistosome miracidia. The hatched miracidia and miracidia enclosed within the eggshell of Schistosoma mansoni were used in this study.Scanning electron microscopy revealed that the body is covered with numerous cilia, 3 different cilia are present, and the major cilia are 8.5 mum in length and 0.25 mum in width, which distribute all over the surface except the anterior tip of the body.The swimming speed of miracidia was measured in NaCl, KCl and sucrase solution. The swimming speed of miracidia is a function of the concentration of NaCl, KCl and suorose. These results indicate that beating frequency of miracidial cilia is depend on the osmotic presure.Control of ciliary activities by exterally applied reagents was studied in triton-extracted model. The extraction and reactivating solution used for triton-extracted model of sperm(Gibbons and Gibbons, 1982)was used for schistosome miracidia. Interestingly enough the beating frequency of cilia is function of NaCl concentation. The beating frequency of cilia is also depend on ATP and Mg++ concentration and pH of medium. In a standard reactivating medium (4mM ATP,lmM MgSO4, pH8.1), the models swim at 1/3 of swimming speed of the live miracidia in water(2m/sec). Ca++ activated partially the ciliary beating, but did not cause the reversed direction of beating. Other divalent cations did not activate the ciliary beating. VO3 caused the inhibition of ciliary beating.Ca++ ionophore and phorbol esters activated the cilial beating of miracidia enclosed within the eggshell. W-7, H-7 and calcium channel blocker inhibited the cilial beating of miracidia enclosed within the eggshell.Pharmacological studies on control mechanism of ciliary activities is now in progress.