Emran Farida, Dowling John E
Department of Molecular and Cellular Biology; Harvard University; Cambridge, MA USA.
Commun Integr Biol. 2010 Sep;3(5):430-2. doi: 10.4161/cib.3.5.12158.
Studies in several vertebrate species have shown that visual sensitivity and a number of other retinal phenomena are regulated by circadian mechanisms. For example, ultra-structural studies of 5 day old zebrafish larvae have shown that synaptic ribbons in photoreceptor terminals undergo dramatic diurnal alterations. These synaptic ribbons are very prominent during the day, but are almost completely absent at night. The implications of this circadian driven process on visual function are not well understood. We recently showed that larval zebrafish essentially lose visual responsiveness at night. This shut-down of retinal function at night is regulated by at least two mechanisms: the disassembly of synaptic ribbons in cone pedicles and a decrease of outer segment activity. Here, we summarize our recently reported observations and further discuss our hypothesis on how this phenomenon of shutting-down retinal function at night may provide a means for zebrafish larvae to conserve energy.
对几种脊椎动物的研究表明，视觉敏感性和许多其他视网膜现象受昼夜节律机制调节。例如，对5天大的斑马鱼幼虫的超微结构研究表明，光感受器末端的突触带会发生显著的昼夜变化。这些突触带在白天非常突出，但在夜间几乎完全不存在。这种昼夜驱动过程对视觉功能的影响尚不清楚。我们最近发现，斑马鱼幼体在夜间基本丧失视觉反应能力。夜间视网膜功能的这种关闭至少受两种机制调节：视锥细胞蒂中突触带的解体和外段活性的降低。在此，我们总结了我们最近报道的观察结果，并进一步讨论了我们的假设，即夜间视网膜功能关闭这一现象可能为斑马鱼幼体提供一种节约能量的方式。
