Ritz T, Adem S, Schulten K
Theoretical Biophysics Group, Beckman Institute, University of Illinois at Urbana-Champaign, 61801, USA.
Biophys J. 2000 Feb;78(2):707-18. doi: 10.1016/S0006-3495(00)76629-X.
A large variety of animals has the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information. It is not known by which biophysical mechanism this magnetoreception is achieved. We investigate the possibility that magnetoreception involves radical-pair processes that are governed by anisotropic hyperfine coupling between (unpaired) electron and nuclear spins. We will show theoretically that fields of geomagnetic field strength and weaker can produce significantly different reaction yields for different alignments of the radical pairs with the magnetic field. As a model for a magnetic sensory organ we propose a system of radical pairs being 1) orientationally ordered in a molecular substrate and 2) exhibiting changes in the reaction yields that affect the visual transduction pathway. We evaluate three-dimensional visual modulation patterns that can arise from the influence of the geomagnetic field on radical-pair systems. The variations of these patterns with orientation and field strength can furnish the magnetic compass ability of birds with the same characteristics as observed in behavioral experiments. We propose that the recently discovered photoreceptor cryptochrome is part of the magnetoreception system and suggest further studies to prove or disprove this hypothesis.
多种多样的动物有能力感知地磁场，并将其用作定向（罗盘）信息的来源。目前尚不清楚这种磁感受是通过何种生物物理机制实现的。我们研究了磁感受涉及自由基对过程的可能性，这些过程由（未配对的）电子与核自旋之间的各向异性超精细耦合所支配。我们将从理论上表明，地磁场强度及更弱的磁场，对于自由基对与磁场的不同排列方式，能够产生显著不同的反应产率。作为磁感觉器官的模型，我们提出一个自由基对系统，该系统1）在分子基质中呈取向有序排列，2）表现出反应产率的变化，从而影响视觉转导通路。我们评估了地磁场对自由基对系统的影响可能产生的三维视觉调制模式。这些模式随取向和场强的变化，能够为鸟类提供与行为实验中观察到的相同特征的磁罗盘能力。我们提出，最近发现的光感受器隐花色素是磁感受系统的一部分，并建议进一步开展研究以证实或证伪这一假设。
