Blue and ultraviolet light induced damage to the Drosophila retina: ultrastructure.
Blue and ultraviolet light induced damage to the Drosophila retina: ultrastructure.
复制标题
蓝光和紫外线对果蝇视网膜造成的损伤：超微结构。
作者：
W. S. Stark;S. D. Carlson
强紫外线 (UV) 和蓝色刺激通过白眼果蝇复眼的主要光感受器类型 R1-6 中的荧光变视紫红质 (M') 光解视紫红质。我们使用高压电子显微镜 (HVEM) 研究了相关的视网膜变性。紫外线引起的损伤的阈值约为 19 log 量子/cm2，而对于蓝色，阈值约为 20。这些强度接近视紫红质光解的动态范围的上限。因此，正如已经发现的视色素的光解作用一样，存在对近紫外线引起的变性的敏化。缺乏维生素 A 可防止光引起的视网膜变性，尤其是在紫外线下。由于维生素 A 缺乏会消除 R1-6 中吸收蓝色的视紫红质和紫外线敏化色素，因此这种变性可能是通过这些光激发色素的量子吸收介导的。强光将横纹肌（含有感光色素的细胞器）的微绒毛转化为致密的链，并且细胞质充满致密的网状结构。这种损伤在刺激后不久就会引起，并且是永久性的。在大多数情况下，二阶中间神经元都不会受到影响。这些结果在其他强光视网膜变性动物模型的背景下进行了讨论。
Intense ultraviolet (UV) and blue stimulation photolyses rhodopsin through a fluorescent metarhodopsin (M') in the predominant photoreceptor type, R1-6, of the compound eye of white eyed Drosophila melanogaster. We investigated the associated retinal degeneration using High Voltage Electron Microscopy (HVEM). The threshold for UV induced damage was about 19 log quanta/cm2 while for blue, the threshold was about 20. These intensities are toward the upper level of the dynamic range for rhodopsin photolysis. Thus, there is a sensitization for near UV induced degeneration as had been found for photolysis of the visual pigment. Vitamin A deprivation protects against light elicited retinal degeneration, particularly in the UV. Since vitamin A deprivation eliminates the blue absorbing rhodopsin and a UV sensitizing pigment in R1-6, the degeneration is likely mediated through quantal absorption through these photoexcitation pigments. Intense light converts the microvilli of the rhabdomeres (the photopigment containing organelles) into dense strands and the cytoplasm fills with a dense reticulum. Such damage is elicited shortly after stimulation and is permanent. Under most conditions, the second order interneurons are spared. These results are discussed in the context of other animal models of intense light retinal degeneration.