Control of ciliary activities of Schistosoma mansoni miracidia using Triton-extracted parasites.

Extraction with 0.04% (w/v) Triton X-100 for 3 min removed the cell membrane from the locomotory cilia of Schistosoma mansoni miracidia while leaving the motile apparatus apparently intact. Immediately after Triton-extracted miracidia were treated by the reactivating solution containing ATP and magnesium ions (Mg2+) at pH 8.1, nearly 100% of Triton-extracted miracidia showed the ciliary beating and swam forward in a manner resembling that of a normal miracidium. In the standard reactivating solution (2 mM ATP, 2 mM Mg2+, pH 8.1), Triton-extracted miracidia swam at a speed of 580 microns/sec; the comparable value for live miracidia in dechlorinated tap water was 2,200 microns/sec. The swimming velocity of Triton-extracted miracidia was dependent on ATP and Mg2+ concentration, pH, and salinity. In a solution containing 0.9% NaCl, Triton-extracted miracidia were not reactivated. Among the nucleotides tested, only ATP was found to induce a significant amount of ciliary motility. In terms of divalent cation specificity, only Mg2+ was capable of producing normal motility. Barium and calcium ions (at 0.5 mM CaCl2) also were capable of activating ciliary motility but were less effective stimulants than Mg2+. However, in 1 mM CaCl2, no ciliary reactivation was observed and cilia became detached from the body surface of the miracidia. Vanadium inhibited ATP-reactivated ciliary beating of Triton-extracted miracidia.