Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA.
Planta. 1989 Aug;179(1):1-10. doi: 10.1007/BF00395764.
A fiber optic microprobe, 5.5 μm in diameter, was used as a detector to measure the light intensity profile at the distal cell surface of Phycomyces blakesleeanus (Burgeff) sporangiophores that were irradiated unilaterally by a collimated xenon source. The light intensity at a fixed location of the cell surface showed large random variations over time which were probably the result of optical effects of particles being carried past the probe by cytoplasmic streaming. The intensity profile, formed around the distal periphery of the cell by the lens action of the sporangiophore, was determined from intensity measurements made while the probe was held fixed and the incident beam direction was varied in angle of azimuth. The resulting profile consisted of two steeply rising sides enclosing a central plateau or shallow well which ranged in fluence rate from 1.6 to 2.2 times that of the incident beam. These experimental findings differ from theoretical modeling where much greater contrast between the sides and central portion of the lens profile was predicted. These results also indicate that the mechanism of phototropic sensory perception in Phycomyces may filter out cytoplasmic light flicker and may not require strong contrasting regions within the lens profile to detect light direction.
一根直径为 5.5μm 的光纤微探针被用作探测器，用来测量被平行光氙光源单侧照射的泡囊梗远端细胞表面的光强分布。细胞表面固定位置的光强随时间呈现出很大的随机波动，这可能是由于细胞质流动携带的颗粒的光学效应造成的。通过泡囊梗的透镜作用形成的细胞远端周围的光强分布，是通过在探针固定时进行强度测量，并改变入射光束的方位角来确定的。所得的光强分布由两个陡峭上升的边缘包围一个中央平台或浅凹组成，其光强度在入射光束的 1.6 到 2.2 倍之间。这些实验结果与理论模型不同，理论模型预测边缘和透镜中央部分之间的对比度要大得多。这些结果还表明，在 Phycomyces 中光向性感觉感知的机制可能过滤掉细胞质的闪烁，并且不需要在透镜轮廓内有强烈的对比区域来检测光的方向。
