Dennison D S, Bozof R P
J Gen Physiol. 1973 Aug;62(2):157-68. doi: 10.1085/jgp.62.2.157.
Phototropic responses to unilateral ultraviolet stimuli were studied to determine whether the response of one side of the cell is affected by the previous exposure of the opposite side to ultraviolet. It has been found that the direction of bending is not parallel to the stimulus direction, but is along a straight line rotated 17 degrees clockwise from the stimulus direction. This deviation indicates that the photoreceptors may be in a state of continual clockwise rotation. If before the stimulus the cell is exposed briefly to ultraviolet and rotated through 90 degrees , the response is not along the 17 degrees line, but is deviated a greater or lesser amount, depending on whether the 90 degrees rotation is clockwise or counterclockwise. This difference is evidence that the first ultraviolet exposure leaves a persistent patch of light-adapted receptors and the shaded part of the cell remains dark adapted. The phototropic stimulus straddles the edge between light- and dark-adapted regions, and the differing responses of the two regions affects the direction of phototropic bending. A phototropic mechanism is proposed which combines the features of local adaptation and photoreceptor rotation.
研究了对单侧紫外线刺激的向光性反应，以确定细胞一侧的反应是否受到另一侧先前紫外线照射的影响。已发现弯曲方向与刺激方向不平行，而是沿着从刺激方向顺时针旋转17度的直线。这种偏差表明光感受器可能处于持续顺时针旋转的状态。如果在刺激之前细胞短暂暴露于紫外线并旋转90度，反应并不沿着17度线，而是或多或少地偏离，这取决于90度旋转是顺时针还是逆时针。这种差异证明第一次紫外线照射留下了持续的光适应受体斑块，而细胞的阴影部分仍保持暗适应。向光性刺激跨越光适应和暗适应区域之间的边缘，两个区域的不同反应影响向光性弯曲的方向。提出了一种结合局部适应和光感受器旋转特征的向光性机制。
