How does light control the activity and electrical properties of neurons integrating arousal behaviour, circadian rhythms, and sleep?

我们星球上的生命暴露在昼夜有规律的变化中。因此，动物进化出了一种24小时计时机制，即所谓的“生物钟”，它将我们的行为和生理调节到昼夜周期(例如，睡眠-醒来周期，新陈代谢)。当动物生活在持续的黑暗中(例如洞穴)时，它的时钟仍然在滴答作响。生物钟的工作原理与正常时钟相似，例如，它们以稳定的速度运行(周期为24小时)，如果出现故障，可以重新设置。在自然界中，这种重置是由环境引起的，即明暗的规律变化。因此，昼夜节律与环境同步。生物钟的独立性和它们与环境沟通的能力的著名例子是时差(由跨时区旅行引起)或倒班工作。如果你是时差，你的生物钟仍然在根据你登上飞机的时间滴答作响，并在半夜告诉你要醒着。但渐渐地，你的体内时钟会调整(同步)到新的时区，你会再次感到舒服。生物钟由时钟基因组成，在大脑的时钟神经元中，时钟基因每24小时启动和关闭一次。经典的遗传学实验大多是用果蝇进行的，它确定了几乎所有的时钟基因和后来被发现与人类相似的时钟机制。然而，目前尚不清楚如何将所有部分整合在一起，形成对光敏感的工作时钟，并能够协调整个动物的生理和行为：这是目前这项研究的总体目标。飞行时钟由150个神经元组成，这些神经元之间通过电信号和化学信号相互通信，这些信号被认为是产生整体昼夜行为的神经元之间的同步节奏。这些脉冲的数量和频率(称为电活动)控制着时钟电路中的信息流，就像计算机一样。我们希望研究在时钟神经元之间传递这些信号(称为通道、共转运体和受体)所涉及的蛋白质，这些神经元反过来控制昼夜行为和睡眠。我们知道时钟对光非常敏感，所以我们对将有关光条件的信息传递给时钟并在时钟周围传递信息的蛋白质感兴趣。我们之前在苍蝇中分离出一种名为隐色素(Cry)的光敏时钟蛋白，后来被证明具有从植物到人类的重要昼夜功能。我们再次利用苍蝇遗传学的力量，发现了另一个名为QSM的关键光传感器，一个名为Shaw的通道，一个名为GABAA的受体和一个名为NKCC的联合转运蛋白，它们都影响着生物钟。在这项提案中，我们想弄清楚它们是如何结合在一起来控制昼夜行为、性唤醒和睡眠的。这将通过回答以下实验问题来实现：1)光激活QSM并导致时钟的分子和行为同步的机制是什么？我们将继续看看人类版本的QSM是否也可以在时钟中发挥作用。2)QSM、Shaw和NKCC在时钟中如何相互作用？3)Shaw如何在时钟神经元中产生电信号，这些信号是如何受光和QSM影响的？这将涉及在苍蝇大脑的时钟神经元上放置小电极，并记录它们在不同光条件下的电信号。4)QSM、NKCC和GABAA受体如何在时钟中共同作用，控制唤醒和睡眠？这项研究将帮助我们更好地了解光对生物钟和睡眠的影响，确定治疗睡眠障碍和时差的新的潜在靶点。对生物钟和睡眠的研究很重要，因为它们深刻地影响着我们的健康、生产力和生活质量。

Life on our planet is exposed to the regular changes of night and day. As a consequence animals have evolved a 24 hour timing mechanism, the so-called 'circadian clock', which tunes our behaviour and physiology to the day-night cycle (e.g. sleep-wake cycles, metabolism). An animal's clock still ticks when it lives in continuous darkness (i.e. a cave). Circadian clocks work similar to a normal clock, e.g. they run at a steady pace (with a 24hr period) and can be reset if they go wrong. In nature this resetting is caused by the environment, i.e. the regular changes of light and dark. As a consequence, circadian rhythms are synchronized with the environment. Famous examples for both the independence of circadian clocks and their ability to communicate with the environment are jetlag (caused by travel across time zones) or shift work. If you are jetlagged, your circadian clock is still ticking according to the time where you boarded your plane and is telling you to be awake in the middle of the night. Gradually though, your internal clock will adjust (synchronize) to the new time zone and you will feel comfortable again. Circadian clocks consist of clock genes that switch on and then switch themselves off every 24hrs in the clock neurons of the brain. Classical genetic experiments mostly performed using the fruit fly Drosophila identified nearly all the clock genes and the clock mechanism that was later found to be similar in humans. However, it is still not known how all the parts are integrated to form a working clock sensitive to light and able to orchestrate the physiology and behaviour of the whole animal: this is the overall aim of the current proposal.The fly clock consists of 150 neurons that communicate with each other via electrical and chemical signals that are thought to synchronise rhythms between these neurons generating the overall circadian behaviour. The number and frequency of these impulses (called electrical activity) controls the flow of information in the clock circuit, much like a computer. We wish to study the proteins involved in relaying these signals (called channels, co-transporters and receptors) between the clock neurons, which in turn control circadian behaviour and sleep. We know that the clock is exquisitely sensitive to light so we are interested in the proteins that transmit information about the light conditions to and around the clock. We previously isolated a light sensitive clock protein called Cryptochrome (Cry) in flies, which later was shown to have important circadian functions from plants to humans. Again we have used the power of fly genetics and discovered another key light sensor called Qsm, a channel called Shaw, a receptor called GABAA and co-transporter called NKCC that all influence the clock. In this proposal we want to work out how they fit together to control circadian behaviour, arousal and sleep. This will be achieved by answering the following experimental questions:1) What is the mechanism by which light activates Qsm and causes molecular and behavioural synchronization of the clock? We will go on to see if the human version of Qsm can also function in the clock.2) How do Qsm, Shaw and NKCC interact with each other in the clock?3) How does Shaw generate electrical signals in the clock neurons and how are these affected by light and Qsm? This will involve placing small electrodes on the clock neurons in the fly's brain and recording their electrical signals under different light conditions.4) How do Qsm, NKCC and GABAA receptors act together in the clock to control arousal and sleep? This research will help us to better understand the effect of light on circadian clocks and sleep identifying new potential targets for treatment of sleep disorders and jetlag. Research into circadian clocks and sleep is important as they profoundly affect our health, productivity and quality of life.