Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, University of Florida, St Augustine, FL 32080, USA.
Integr Comp Biol. 2013 Jul;53(1):144-53. doi: 10.1093/icb/ict020. Epub 2013 May 2.
Circadian changes in visual sensitivity have been observed in a wide range of species, vertebrates, and invertebrates, but the processes impacted and the underlying mechanisms largely are unexplored. Among arthropods, effects of circadian signals on vision have been examined in most detail in the lateral compound eye (LE) of the American horseshoe crab, Limulus polyphemus, a chelicerate arthropod. As a consequence of processes influenced by a central circadian clock, Limulus can see at night nearly as well as they do during the day. The effects of the clock on horseshoe crab LE retinas are diverse and include changes in structure, gene expression, and rhabdom biochemistry. An examination of the known effects of circadian rhythms on LEs shows that the effects have three important outcomes: an increase in visual sensitivity at night, a rapid decrease in visual sensitivity at dawn, and maintenance of eyes in a relatively low state of sensitivity during the day, even in the dark. All three outcomes may be critically important for species' survival. Specific effects of circadian rhythms on vision will certainly vary with species and according to life styles. Studies of the circadian regulation of Limulus vision have revealed that these effects can be extremely diverse and profound and suggest that circadian clocks can play a critical role in the ability of animals to adapt to the dramatic daily changes in ambient illumination.
在广泛的物种中，包括脊椎动物和无脊椎动物，都观察到了视觉敏感性的昼夜变化，但受影响的过程和潜在的机制在很大程度上尚未被探索。在节肢动物中，昼夜信号对视觉的影响在美洲鲎的侧复眼 (LE) 中得到了最详细的研究，美洲鲎是一种螯肢节肢动物。由于受中央生物钟影响的过程，鲎在夜间的视力几乎与白天一样好。生物钟对鲎 LE 视网膜的影响是多种多样的，包括结构、基因表达和光感受器生物化学的变化。对已知昼夜节律对 LE 的影响的检查表明，这些影响有三个重要结果：夜间视觉敏感性增加，黎明时视觉敏感性迅速下降，以及即使在黑暗中，白天眼睛也保持相对较低的敏感性。所有这三个结果对于物种的生存都可能至关重要。昼夜节律对视觉的具体影响肯定会因物种和生活方式而异。对鲎视觉的昼夜节律调节的研究表明，这些影响可能非常多样化和深刻，并表明生物钟在动物适应环境光照的剧烈昼夜变化的能力中可以发挥关键作用。
