Robinson K R, Miller B J
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
Dev Biol. 1997 Jul 1;187(1):125-30. doi: 10.1006/dbio.1997.8600.
Unidirectional blue light directs the rhizoid-thallus axis in the apolar zygotes of Fucus and Pelvetia. Here, it is shown that blue light (but not red light) increased cyclic GMP levels of Pelvetia zygotes by about a factor of 2. When the increase in cyclic GMP was blocked by a guanylyl cyclase inhibitor, photopolarization was also blocked. Bathing the cells in a permeant cyclic GMP analog, which should tend to collapse intracellular cyclic GMP gradients, reduced the degree of photopolarization. Growing the cells in the dark in a gradient of the analog caused the rhizoids to tend to form on the low concentration side. It appears that the stimulation of the blue light photoreceptors on the side nearer the light activates guanylyl cyclase and results in a transcytoplasmic cyclic GMP gradient that is necessary for polarization.
单向蓝光引导墨角藻属和鹿角菜属无极性合子中假根-叶状体轴的生长方向。本文表明，蓝光（而非红光）可使鹿角菜属合子的环鸟苷酸（cGMP）水平提高约2倍。当鸟苷酸环化酶抑制剂阻断cGMP的增加时，光极化作用也会被阻断。用一种可渗透的cGMP类似物处理细胞，这会使细胞内cGMP梯度趋于消失，从而降低光极化程度。在黑暗中，让细胞在该类似物的梯度环境中生长，会使假根倾向于在低浓度一侧形成。似乎靠近光源一侧的蓝光光感受器受到刺激会激活鸟苷酸环化酶，并产生一个跨细胞质的cGMP梯度，这是极化所必需的。
