Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism

摘要

常感兴趣的一个问题。人们知道，UV—A/蓝光rn光受体“隐花色素”(Cry)调控果蝇依赖于光的rn磁感应。现在，Steven Reppert及其同事利用基rn因操纵发现，来自"王蝶”的两种“隐花色素”rn(分别是与果蝇相似的Cryl和与脊椎动物相似rn的Cry 2)能够恢复缺失cry基因的果蝇的磁感rn应。这表明，两种类型的Cry在迂徙的"王蝶"rn体内都能通过一个目前仍不清楚的机制感应磁rn场，而且光敏性也以某种方式参与到了其中。%Understanding the biophysical basis of animal magnetoreception has been one of the greatest challenges in sensory biology. Recently it was discovered that the light-dependent magnetic sense of Drosophila melanogasteris mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry)'. Here we show, using a transgenic approach, that the photoreceptive, Drosophila-like type 1 Cry and the transcriptionally repressive, vertebrate-like type 2 Cry of the monarch butterfly (Danaus plexippus) can both function in the magnetoreception system of Drosophila and require UV-A/blue light (wavelength below 420 nm) to do so. The lack of magnetic responses for both Cry types at wavelengths above 420 nm does not fit the widely held view that tryptophan triad-generated radical pairs mediate the ability of Cry to sense a magnetic field. We bolster this assessment by using a mutant form of Drosophila and monarch type 1 Cry and confirm that the tryptophan triad pathway is not crucial in magnetic transduction. Together, these results suggest that animal Crys mediate light-dependent magnetoreception through an unconventional photochemical mechanism. This work emphasizes the utility of Drosophila transgenesis for elucidating the precise mechanisms of Cry-mediated magnetosensitivity in insects and also in vertebrates such as migrating birds.