Takahashi T, Kubota M, Watanabe M, Yoshihara K, Derguini F, Nakanishi K
Suntory Institute for Bioorganic Research, Osaka, Japan.
FEBS Lett. 1992 Dec 21;314(3):275-9. doi: 10.1016/0014-5793(92)81488-8.
The blind mutant FN68 of the unicellular flagellate green alga Chlamydomonas reinhardtii is negatively phototactic in the presence of the native chromophore all-trans retinal. In contrast, analog chromophores such as a ring-acyclic retinal and those in which trans/cis isomerization about the C11 = C12 double bond was blocked induced predominantly positive phototaxis in the same strain under the same experimental conditions. These observations can be interpreted by assuming that the negative and the positive phototaxis is mediated distinctively by two rhodopsin species which differ in their affinities with the exogenous chromophores. However, a more reasonable explanation, which requires fewer assumptions, is that the sign of phototaxis depends on a delay in intracellular photosignal transduction. This novel view was deduced directly from the widely accepted hypothesis [1980, Microbiol. Rev. 44, 572-630] on phototaxis mechanisms.
单细胞鞭毛绿藻莱茵衣藻的失明突变体FN68在天然发色团全反式视黄醛存在的情况下表现出负向光性。相比之下，在相同的实验条件下，类似的发色团，如环-无环视黄醛以及那些C11 = C12双键的反式/顺式异构化被阻断的发色团，在同一菌株中主要诱导正向光性。这些观察结果可以通过假设负向光性和正向光性分别由两种视紫红质介导来解释，这两种视紫红质对外源发色团的亲和力不同。然而，一个更合理的解释（需要的假设更少）是，光性的正负取决于细胞内光信号转导的延迟。这一新观点是直接从关于光性机制的广泛接受的假设[1980年，《微生物学评论》44卷，572 - 630页]推导出来的。
