Rhythmic emergence of Schistosoma mansoni cercariae from Biomphalaria glabrata: control by illumination |
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| Authors: | H L Asch |
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| Affiliation: | 1. Department of General Medicine, Hirosaki University School of Medicine & Hospital, 53 Hon-cho, Hirosaki-shi 036-8563, Japan;2. Development of Community Healthcare, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki-shi, Aomori 036-8562, Japan;1. Institute of Biology and Soil Science, Far Eastern Branch, Russian Academy of Sciences, Prospect 100-letija, 159, Vladivostok 690022, Russia;2. Department of Cell Biology and Genetics, Far Eastern Federal University, October str., 27, Vladivostok 690000, Russia |
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| Abstract: | The rhythmic release of Schistosoma mansoni cercariae from Biomphalaria glabrata was studied. Reversal of emergence from diurnal to nocturnal periodicity was confirmed as by previous investigators. Similar experiments using a black pigmented strain of host whose shell and tissues are opaque, gave identical results. Exposure of snails to different portions of the light spectrum showed that cercarial release could be elicited by upper and lower ends of the visible range, as well as white light. A threshold intensity of approximately 100–200 ergs/cm2/sec was required to induce emergence. No relationship was found between conditions of illumination and temperature of snails or snail shells. It is concluded that the light-induced emergence of cercariae is initiated by light itself, and not by any change in temperature within the snail. |
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