The zebrafish represents a powerful model for exploring how light regulates the circadian clock due to the direct light sensitivity of its peripheral clocks, a property that is retained even in organ cultures as well as zebrafish-derived cell lines. Light-inducible expression of the per2 clock gene has been predicted to play a vital function in relaying light information to the core circadian clock mechanism in many organisms, including zebrafish. To directly test the contribution of per2 to circadian clock function in zebrafish, we have generated a loss-of-function per2 gene mutation. Our results reveal a tissue-specific role for the per2 gene in maintaining rhythmic expression of circadian clock genes, as well as clock-controlled genes, and an impact on the rhythmic behavior of intact zebrafish larvae. Furthermore, we demonstrate that disruption of the per2 gene impacts on the circadian regulation of the cell cycle in vivo. Based on these results, we hypothesize that in addition to serving as a central element of the light input pathway to the circadian clock, per2 acts as circadian regulator of tissue-specific physiological functions in zebrafish.

中文翻译：

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时期 2：多种组织特异性昼夜节律功能的调节器。

斑马鱼代表了一个强大的模型，用于探索光如何调节生物钟，这是由于其外围时钟的直接光敏感性，即使在器官培养以及斑马鱼衍生的细胞系中也保留了这一特性。已预测 per2 时钟基因的光诱导表达在将光信息传递到许多生物体（包括斑马鱼）的核心生物钟机制方面发挥重要作用。为了直接测试 per2 对斑马鱼生物钟功能的贡献，我们产生了功能丧失的 per2 基因突变。我们的结果揭示了 per2 基因在维持生物钟基因以及时钟控制基因的节律表达方面的组织特异性作用，以及对完整斑马鱼幼虫节律行为的影响。此外，我们证明了 per2 基因的破坏会影响体内细胞周期的昼夜节律调节。基于这些结果，我们假设除了作为生物钟光输入通路的中心元素外，per2 还充当斑马鱼组织特异性生理功能的昼夜节律调节剂。