Signal Transduction relevant to Cherno-klinokinesis of schistosome miracidiai toward intermediate snail host

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Schistosorne miracidia show chemo-klinokinesis toward the secretions of the intermediate snails (Snail Conditioned Water : SCW). A certain kinds of nematode larvae are reported to loose their chennotactic activity when their sensory papillae are overspread by some kinds of lectin. Miracidia must recognize SCW by the sensory papillae on their body surface. The present study was attempted to show the presence of receptor on the miracidia by using lectin binding. Materials and Method : Miracidia were incubated with any hind of lectin. They were then examined for their swimming behavior and for cheinotactic action toward SCW. Lectin used was WGA, PNA, GS-II and MPA. Results and Discussion : Of lectin examined, only WGA, at high concentration (100 ug/ml), caused the behavior, change (frequent change in swimming direction). And miracidia pre-incubated with WGA, at 250 ug/ml for 10 min, did not show the cherotactic action toward SCW. These results indicate that 1) the receptors of SCW are pre … More sent on the body surface of miracidia, and 2) miracidia loose chemotactic action when the receptors are overspread by WGA. Recently we reported that CAMP induces the frequent change in swimming direction of miracidia as well as SCW does. Then an attempt was made to examine whether WGA inhibits cAMP-induced miracidial behavior change. Miracidia pre-incubated with WGA showed the frequent change of swimming direction. Since this result suggests the role of cAMP as a 2^<nd> messenger of the signal transduction of chemo-klinokinesis of miracidia, an attempt was made to verify our hypothesis. Miracidia were incubated with the reagents that lower the intercellular e_AMP concentration (MDL-12,330A, SQ 22526, imidazole) or inhibitor of protein kinase A (PKI(14-22) amid), and then examined for their chemotactic action toward SCW. As was expected, these miracidia did reduce the chemotacitc activity toward SCW. These results clearly indicate that cAMP plays an important role in chemo-klinokinesis. of miracidia toward SCW. Less