Control of Ciliary Beating of Schistosomal Miracidia

血吸虫毛虫被大量纤毛完全覆盖。毛虫纤毛的猛烈拍打是卵孵化、水中游泳和侵入中间钉螺的驱动力。本研究旨在探讨马氏血吸虫毛虫纤毛跳动的调控机制。虽然外界刺激会引起纤毛跳动的变化，但本研究探讨了渗透压对纤毛跳动的控制机制以及趋化游泳活动中纤毛跳动的可能变化。结果表明：1)卵的孵化是纤毛猛烈跳动和蛋壳肿胀共同作用的结果；2)膜通透性cAMP、Forskokin和IBMX引起毛虫纤毛跳动，并在高渗透压下保持平静。3)蛋白激酶A抑制剂和钾离子通道阻滞剂抑制水中毛虫的纤毛跳动；4)膜通透性cAMP，而不是非通透性cAMP，使毛虫采取类似于毛虫对条件水的趋化(运动)活性；5)丝氨酸抑制毛虫对条件水的趋化活性。毛虫的被膜上有渗透压感受器。当受体被低渗透压激活时，钾离子通道被激活。钾离子的流入激活了腺苷环化酶。然后，cAMP浓度增加激活微管运动，然后开始纤毛加热。当毛虫暴露在高渗透压下时，钾离子通道被灭活。CAMP浓度降低抑制纤毛搏动。趋化活性不受纤毛跳动的控制。

Schistosomal miracidia are completely covered by numerous cilia. The vigorous beating of cilia of miracidia is the driving force of hatching of the egg, swimming in water and invasion into the intermediate snail. The present study aimed at examination of the control mechanism of ciliary beating of miracidia of Schistosoma manosni.Although some external stimulus cause the change in the ciliary beating, the present study dealt with the control mechanism of ciliary beating by osmotic pressure and possible change of ciliaty beating in chemotactic swimming activity.The highlights of the results are 1) that hatching of the eggs is caused by the combination of vigorous beating of cilia and swelling of eggshell, 2) that membrane permeable cAMP, forskokin and IBMX cause the ciliary beating of miracidia which remain to he quiet under high osmotic pressure. 3) that protein kinase A inhibitor and potassium ion channel blocker suppress the ciliary beating of miracidia which swim in water, 4) that membrane permeable cAMP, but not non-permeable cAMP, cause miracidia to take peculiar swimming activity which mimic the chemotactic (klinokinetic) activity of miracidia to snail conditioned water (SCW), and 5) that chemotactic activity of miracidia to SCW is inhibited by eserine.Our results propose the possible control mechanism of ciliary beating of miracidia. Osmotic receptors are present over the integument of miracidia. When the receptors are activated by low osmotic pressure, potassium ion channel is activated. Influx of potassium ions activates adenyl cyclase. Then increase in cAMP concentration activates microtuble movement, then ciliary heating starts. When miracidia are exposed to high osmotic pressure, potassium ion channels are inactivated. Decrease in cAMP concentration suppress the ciliary beating. Chemotactic activity is not controlled by ciliary beating.