Sineshchekov O A, Govorunova E G, Dér A, Keszthelyi L, Nultsch W
Biology Department, Moscow State University, Russia.
Biophys J. 1994 Jun;66(6):2073-84. doi: 10.1016/S0006-3495(94)81002-1.
Reconstitution of the photoelectric responses involved in photosensory transduction in "blind" cells of Chlamydomonas reinhardtii carotenoid-deficient mutants was studied by means of a recently developed population method. Both the photoreceptor current and the regenerative response can be restored by addition of all-trans-retinal, 9-demethyl-retinal, or dimethyl-octatrienal, while the retinal analogs prevented from 13-cis/trans isomerization, 13-demethyl-retinal and citral, are not effective. Fluence dependence, spectral sensitivity, and effect of hydroxylamine treatment on retinal-induced photoelectric responses are similar to those found earlier in green strains of Chlamydomonas, although an alternative mechanism of antenna directivity in white cells of reconstituted "blind" mutants (likely based on the focusing effect of the transparent cell bodies) leads to the reversed sign of phototaxis in mutant cells under the same conditions. The results obtained indicate that both photoreceptor current and regenerative response are initiated by the same or similar rhodopsins with arhaebacterial-like chromophore(s) and prove directly the earlier suggested identity of the photoreceptor pigment(s) involved in photomotile and photoelectric responses in flagellated algae.
利用最近开发的群体方法，研究了莱茵衣藻类胡萝卜素缺陷型突变体“失明”细胞中光感受转导所涉及的光电反应的重建。通过添加全反式视黄醛、9-去甲基视黄醛或二甲基辛三烯醛，可以恢复光感受器电流和再生反应，而阻止13-顺式/反式异构化的视黄醛类似物13-去甲基视黄醛和柠檬醛则无效。光通量依赖性、光谱敏感性以及羟胺处理对视网膜诱导的光电反应的影响与早期在衣藻绿色菌株中发现的相似，尽管重建的“失明”突变体白细胞中天线方向性的另一种机制（可能基于透明细胞体的聚焦效应）导致在相同条件下突变体细胞中趋光性的符号相反。获得的结果表明，光感受器电流和再生反应都是由具有类似古细菌发色团的相同或相似视紫红质引发的，并直接证明了早期提出的参与鞭毛藻光运动和光电反应的光感受器色素的同一性。
