Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3QZ, UK.
J R Soc Interface. 2012 Dec 7;9(77):3329-37. doi: 10.1098/rsif.2012.0374. Epub 2012 Sep 12.
According to the radical pair model, the magnetic compass sense of migratory birds relies on photochemical transformations in the eye to detect the direction of the geomagnetic field. Magnetically sensitive radical pairs are thought to be generated in cryptochrome proteins contained in magnetoreceptor cells in the retina. A prerequisite of the current model is for some degree of rotational ordering of both the cryptochromes within the cells and of the cells within the retina so that the directional responses of individual molecules do not average to zero. Here, it is argued that anisotropic distributions of radical pairs can be generated by the photoselection effects that arise from the directionality of the light entering the eye. Light-induced rotational order among the transient radical pairs rather than intrinsic ordering of their molecular precursors is seen as the fundamental condition for a magnetoreceptor cell to exhibit an anisotropic response. A theoretical analysis shows that a viable compass magnetoreceptor could result from randomly oriented cryptochromes contained in randomly oriented cells distributed around the retina.
根据自由基对模型，候鸟的磁罗盘感依赖于眼睛中的光化学反应来检测地磁场的方向。磁性敏感的自由基对被认为是在视网膜中的磁受体细胞中包含的隐花色素蛋白中产生的。当前模型的一个前提条件是细胞内的隐花色素和视网膜内的细胞在某种程度上具有旋转有序性，以便单个分子的方向响应不会平均为零。在这里，有人认为，由进入眼睛的光的方向性引起的光选择效应可以产生自由基对的各向异性分布。光诱导的瞬态自由基对之间的旋转有序性而不是其分子前体的固有有序性被视为磁受体细胞表现出各向异性响应的基本条件。理论分析表明，来自随机取向的细胞中的随机取向的隐花色素可以产生可行的罗盘磁受体。
