Circadian Photoreception in Drosophila Melanogaster

描述(申请人提供)：几乎所有的生物体都有天生的时间观念。从蓝藻到人类，内在的生物钟24小时都深刻地影响着生理和行为。例如，我们每天几乎在同一时间睡觉和起床。我们对包括人类在内的许多生物体昼夜节律背后的分子机制的了解，极大地得益于果蝇的遗传学。虽然我们对昼夜节律的产生有很好的了解，但我们对使昼夜节律与日光强度变化同步的信号转导机制知之甚少。这是一个根本性的问题，因为昼夜节律需要适当地同步才能有益。在果蝇中，已经确定了一条专门的昼夜节律光输入途径：Cay(隐色素)是光感受器，Tim(永恒)是起搏器内的靶分子。我们将使用果蝇提供的强大的分子、细胞和遗传工具来实现我们的目标：在分子水平上了解光是如何激活CRY输入通路以同步昼夜节律起搏器的。调查将遵循三条主要路线。第一个目标将检验这样的假设，即光引发CREY构象的变化，从而改变其稳定性和与目标蛋白质结合的能力。在第二个目标中，我们将确定与哭声光输入途径相关的候选基因的特征。最后，对于第三个目标，我们将通过对改变昼夜节律光反应的突变体进行无偏见的筛选，来识别这一途径的新组成部分。综合起来，这些方法应该会从根本上促进我们对昼夜节律光接收的理解。我们的工作也将有助于理解昼夜节律产生的一般原理和昼夜节律夹带的过程。最近对人类昼夜节律的临床相关性以及由昼夜节律功能障碍引起的发病率的认识，使理解这些基本机制成为一个重要的目标。

DESCRIPTION (provided by applicant): Almost all organisms have an innate sense of time. From cyanobacteria to humans, intrinsic circadian clocks profoundly influence physiology and behavior on a 24-hour basis. For example, we sleep and wake every day at about the same time. Our knowledge of the molecular mechanisms underlying circadian rhythms in many organisms including humans has benefited immensely from the genetics of Drosophila melanogaster. Although we have a good understanding of how circadian oscillations are generated, we know little about the signal transduction mechanisms that synchronize the circadian clock with daily changes in light intensity. This is a fundamental question, because circadian rhythms need to be properly synchronized to be beneficial. In Drosophila melanogaster, a dedicated circadian light input pathway has been identified: CRY (CRYPTOCHROME) is the photoreceptor and TIM (TIMELESS) the target molecule within the pacemaker. We will use the powerful molecular, cellular and genetic tools that Drosophila offers to achieve our goal: understanding at a molecular level how light activates the CRY input pathway to synchronize the circadian pacemaker. Three major lines of investigation will be followed. The first aim will test the hypothesis that light triggers a change in CRY conformation that alters its stability and its ability to bind to target proteins. With the second aim, we will characterize genes identified as promising candidates for their involvement in the CRY light input pathway. Finally, with the third aim, we will identify novel components of this pathway by performing an unbiased screen for mutants that alter circadian photo responses. Combined, these approaches should fundamentally advance our understanding of circadian photoreception. Our work will also contribute to understanding general principles of circadian rhythm generation and the process of circadian entrainment. Recent appreciation of the clinical relevance of human circadian rhythms and the morbidity caused by their dysfunction, as occurs in shift workers, makes understanding of these basic mechanisms an important objective