Nollen P M
Department of Biological Sciences, Western Illinois University, Macomb 61455.
Int J Parasitol. 1994 Aug;24(5):637-42. doi: 10.1016/0020-7519(94)90115-5.
Echinostoma trivolvis eggs developed to mature miracidia in both dark and light culture conditions as early as 7 days. Hatching initially occurred in eggs exposed to incandescent light on day 11. Those exposed to fluorescent light first hatched on day 13. Maximum hatching (50+ miracidia/day) lasted only over a 3-day span with the entire hatching period being at the most 5 days. Eggs stored in complete darkness for 21 days developed to mature miracidia in 9 days, and, when exposed to light, gave a 50+ hatch the next day. Those eggs stored for 28 and 35 days developed normally but never hatched upon exposure to light. Miracidia hatched at all times of the day without a circadian pattern. Miracidia that hatched from these trials exhibited a definite negative geotaxis in a four-tube vertical system. This response was either negated in open tubes or dominated by a positive phototaxis in the open-bottomed tubes. In horizontal chambers without the depth component, a strong positive phototaxis was also demonstrated. Miracidia showed a positive klinokinetic response, as determined in phi-chambers, to acidic compounds such as aspartic, glutamic, hydrochloric, sulfuric, and acetic acids. Snail-conditioned water prepared from Helisoma trivolvis snails also elicited a positive response. The neutral amino acid, leucine, and possible snail excretion products, Mg2+ and ammonia, did not stimulate these echinostroma miracidia.
三岐棘口吸虫卵在黑暗和光照培养条件下早在7天就发育为成熟毛蚴。最初在第11天暴露于白炽灯下的卵开始孵化。暴露于荧光灯下的卵在第13天首次孵化。最大孵化率（每天50多个毛蚴）仅持续3天，整个孵化期最长为5天。在完全黑暗中储存21天的卵在9天内发育为成熟毛蚴，当暴露于光线下时，第二天孵化率达到50多个。那些储存28天和35天的卵发育正常，但暴露于光线下时从未孵化。毛蚴在一天中的任何时候都能孵化，没有昼夜节律模式。从这些试验中孵化出的毛蚴在四管垂直系统中表现出明确的负趋地性。这种反应在开口管中被抵消，或者在底部开口的管中被正趋光性主导。在没有深度成分的水平室中，也表现出强烈的正趋光性。如在φ室中所确定的，毛蚴对酸性化合物如天冬氨酸、谷氨酸、盐酸、硫酸和乙酸表现出正的动性反应。由三角帆蚌制备的蜗牛条件水也引发了阳性反应。中性氨基酸亮氨酸以及可能的蜗牛排泄产物镁离子和氨不会刺激这些棘口吸虫毛蚴。
