Analysis of the circadian clock at the single cell level in a multi-cellular context.

生活在地球上最重要的适应之一是适应每天的光线波动。为了科普这一点，从简单的原核生物到像我们这样复杂的多细胞生命，生物体已经进化出了一个内源性计时器，即生物钟。生物钟允许生物体对活动和过程进行计时，以便它们在一天中的最佳时间发生。生物钟还允许生物体测量白天的长度，从而测量季节，并相应地改变其生物学。因此，生物钟影响一系列生物过程也就不足为奇了。在植物中，这包括关键的农业性状，如开花时间，休眠，水分利用效率，氮代谢和产量。从长远来看，我们对生物钟的研究可能会为新作物品种的开发提供信息并产生影响。我们目前对生物钟的理解主要是基于对整株植物或植物群的实验。多年来，数学建模和整厂实验的结合使我们对时钟组件及其如何组合的理解取得了惊人的突破。数学模型提供了一个概念框架，使我们能够测试想法并了解生物钟的不同组成部分如何相互作用。然而，这项工作有一个关键问题。它假设植物中的每个细胞都有一个行为相同的时钟。实验证据与这一观点相矛盾，但直到最近，我们还没有分析植物单细胞生物钟的工具。利物浦大学（Liverpool University）最近开发出一种方法，利用哺乳动物细胞研究中开创的活细胞成像方法，监测活幼苗中单细胞的生物钟。在这个项目中，我们将调查与细胞分辨率的生物钟。然后，与剑桥Sainsbury实验室的昼夜节律建模和单细胞分析专家合作，我们将从这些单细胞数据中提取重要信息，并建立细胞类型特定的数学模型。这些模型将通过进一步的实验进行测试，并将回答昼夜节律生物学中长期存在的问题，例如细胞类型之间的时钟网络如何变化？在一个细胞中有多个振荡器吗？最后，我们将把我们的模型扩展到多细胞环境中，并使用它们来指导实验，以研究网络如何在细胞之间耦合，以及这如何影响整个植物的节奏。

One of the most important adaptations to living on the Earth is to the daily fluctuation in light. To cope with this, from simple prokaryotes to complex multicellular life like ourselves, organisms have evolved an endogenous timer, the circadian clock. Circadian clocks allow an organism to time activities and processes so that they occur at the optimum time of day. The clock also allows an organism to measure day length, and thus the seasons and to alter its biology accordingly. It is not surprising, therefore, that the circadian clock affects a huge range of biological processes. In plants, this includes key agricultural traits such as flowering time, dormancy, water use efficiency, nitrogen metabolism and yield. In the long term our work on the circadian clock is likely to inform and impact the development of new crop cultivars. Our current understanding of the circadian clock is largely based on experiments on whole plants or groups of plants. Over the years, a combination of mathematical modelling and whole plant experiments have led to striking breakthroughs in our understanding of the clock components and how they fit together. Mathematical models provide a conceptual framework allowing us to test ideas and understand how different components of the circadian clock interact. However, this body of work has a critical problem. It assumes that every cell in a plant has a clock that behaves identically. Experimental evidence contradicts this idea, but until recently we have not had the tools to analyse the clock in single plant cells.At Liverpool University, using live-cell imaging approaches pioneered for mammalian cell work, we have recently developed a method to monitor the clock in single cells across a living seedling. In this project we will survey the circadian clock with cellular resolution. Then, in collaboration with experts in circadian modelling and single cell analysis at the Sainsbury Laboratory, Cambridge, we will extract important information from this single cell data and build cell-type specific mathematical models. These models will be tested with further experiments, and will answer long-standing questions in circadian biology, such as how do clock networks vary between cell-types? And are there multiple oscillators in a single cell? Finally we will extend our models into a multicellular context, and use them to direct experiments to investigate how networks are coupling between cells, and how this affects rhythms in the whole plant.