Devlin Paul F
Division of life Sciences, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 8WA, UK.
J Exp Bot. 2002 Jul;53(374):1535-50. doi: 10.1093/jxb/erf024.
The circadian clock forms one of the most fascinating adaptations to life on earth. Organisms can not only anticipate the day/night cycle but can make use of an internal clock to measure daylength as an indicator of the changing of the seasons. The innate period of the clock is not exactly equal to 24 h, but is reset each day by environmental signals at dawn and dusk, most notably by changes in light and temperature. This ability to re-entrain also ensures that the clock is synchronized with the day/night cycle which in turn is crucial for anticipation of dawn and dusk. Recent advances in the field have identified the photoreceptors involved in resetting the clock in several systems. This has revealed surprising similarities, but also key differences in the circadian systems of plants, fungi, insects, and mammals. One recurring feature emerging from this research is that the photoreceptors themselves are under the control of the clock with transcript abundance being tightly regulated. Furthermore, elements of a feedback pathway whereby the clock modulates the activity of the light input pathway are now being identified.
昼夜节律钟是地球上生命最迷人的适应性之一。生物体不仅能够预测昼夜循环，还能利用内部时钟来测量日照长度，以此作为季节变化的指标。生物钟的固有周期并不恰好等于24小时，而是每天在黎明和黄昏时通过环境信号重新设定，最显著的是光照和温度的变化。这种重新调整的能力还确保了生物钟与昼夜循环同步，而这反过来对于预测黎明和黄昏至关重要。该领域的最新进展已经在多个系统中确定了参与重置生物钟的光感受器。这揭示了惊人的相似之处，但植物、真菌、昆虫和哺乳动物的昼夜节律系统也存在关键差异。这项研究中出现的一个反复出现的特征是，光感受器本身受生物钟控制，转录本丰度受到严格调节。此外，现在正在确定生物钟调节光输入途径活动的反馈途径的要素。
