Watanabe M, Furuya M
Department of Botany, Faculty of Science, University of Tokyo, Hongo, Tokyo, 113, Japan.
Plant Physiol. 1978 May;61(5):816-8. doi: 10.1104/pp.61.5.816.
Positive phototaxis in cell populations of a phytoflagellate Cryptomonas sp. was recorded photoelectrically when the duration and intensity of repeated pulses of monochromatic yellow light (570 nm) interspersed with darkness were varied. Irrespective of the duration of the light pulses, phototactic responses to repeated pulses were as great as those to continuous irradiation and were linearly dependent on the logarithm of total incident light energy when the dark interval was shorter than 60 milliseconds. Under these conditions, reciprocity between duration and intensity held well. In contrast, when the dark interval exceeded 250 milliseconds, the responses were remarkably reduced regardless of light duration and were not affected by increasing the intensity of actinic light pulses.The present results clearly indicate that continuous stimulation with actinic light is not essential for the maximum effect, but that the length of dark interval is crucial in phototactic response.
当单色黄光（570纳米）重复脉冲的持续时间和强度与黑暗交替变化时，对一种植物鞭毛虫隐滴虫属细胞群体的正向趋光性进行了光电记录。无论光脉冲的持续时间如何，当黑暗间隔短于60毫秒时，对重复脉冲的趋光反应与对连续照射的反应一样大，并且与总入射光能的对数呈线性相关。在这些条件下，持续时间和强度之间的互易关系保持良好。相比之下，当黑暗间隔超过250毫秒时，无论光持续时间如何，反应都会显著降低，并且不受光化光脉冲强度增加的影响。目前的结果清楚地表明，光化光的连续刺激对于最大效应并非必不可少，但黑暗间隔的长度在趋光反应中至关重要。
