Fuhrmann M, Stahlberg A, Govorunova E, Rank S, Hegemann P
Institut für Biochemie I, Universität Regensburg, 93040 Regensburg, Germany.
J Cell Sci. 2001 Nov;114(Pt 21):3857-63. doi: 10.1242/jcs.114.21.3857.
The chlamyopsin gene (cop) encodes the most abundant eyespot protein in the unicellular green alga Chlamydomonas reinhardtii. This opsin-related protein (COP) binds retinal and was thought to be the photoreceptor controlling photomovement responses via a set of photoreceptor currents. Unfortunately, opsin-deficient mutants are not available and targeted disruption of non-selectable nuclear genes is not yet possible in any green alga. Here we show that intron-containing gene fragments directly linked to their intron-less antisense counterpart provide efficient post-transcriptional gene silencing (PTGS) in C. reinhardtii, thus allowing an efficient reduction of a specific gene product in a green alga. In opsin-deprived transformants, flash-induced photoreceptor currents (PC) are left unchanged. Moreover, photophobic responses as studied by motion analysis and phototaxis tested in a light-scattering assay were indistinguishable from the responses of untransformed wild-type cells. We conclude that phototaxis and photophobic responses in C. reinhardtii are triggered by an as yet unidentified rhodopsin species.
眼点视蛋白基因（cop）编码单细胞绿藻莱茵衣藻中最丰富的眼点蛋白。这种与视蛋白相关的蛋白（COP）结合视黄醛，曾被认为是通过一组光感受器电流控制光运动反应的光感受器。不幸的是，目前尚无视蛋白缺陷型突变体，而且在任何绿藻中都还无法对不可选择的核基因进行靶向破坏。在此我们表明，与不含内含子的反义对应物直接相连的含内含子基因片段在莱茵衣藻中可提供有效的转录后基因沉默（PTGS），从而能够有效降低绿藻中特定基因产物的含量。在缺乏视蛋白的转化体中，闪光诱导的光感受器电流（PC）保持不变。此外，通过运动分析研究的避光反应以及在光散射测定中测试的趋光性与未转化的野生型细胞的反应没有区别。我们得出结论，莱茵衣藻中的趋光性和避光反应是由一种尚未确定的视紫红质触发的。
