Night-migratory songbirds appear to sense the direction of the Earth's magnetic field via radical pair intermediates formed photochemically in cryptochrome flavoproteins contained in photoreceptor cells in their retinas. It is an open question whether this light-dependent mechanism could be sufficiently sensitive given the low-light levels experienced by nocturnal migrants. The scarcity of available photons results in significant uncertainty in the signal generated by the magnetoreceptors distributed around the retina. Here we use results from Information Theory to obtain a lower bound estimate of the precision with which a bird could orient itself using only geomagnetic cues. Our approach bypasses the current lack of knowledge about magnetic signal transduction and processing in vivo by computing the best-case compass precision under conditions where photons are in short supply. We use this method to assess the performance of three plausible cryptochrome-derived flavin-containing radical pairs as potential magnetoreceptors.

中文翻译：

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夜间航行：暗光下自由基对磁感受灵敏度的基本限制

夜间迁徙的鸣禽似乎通过其视网膜感光细胞所含的隐花色素黄素蛋白中光化学形成的自由基对中间体感知地球磁场的方向。考虑到夜间移民经历的低光照水平，这种依赖光的机制是否足够敏感，这是一个悬而未决的问题。可用光子的稀缺导致分布在视网膜周围的磁感受器产生的信号存在很大的不确定性。在这里，我们使用信息论的结果来获得鸟类仅使用地磁线索可以定位自己的精度的下限估计。我们的方法绕过了目前缺乏关于磁信号转导和处理的知识体内通过在光子供应不足的情况下计算最佳罗盘精度。我们使用这种方法来评估三个似是而非的隐花色素衍生的含黄素自由基对作为潜在磁感受器的性能。