How do H2A.Z-nucleosomes control the temperature transcriptome?

所有生物对它们的温度都很敏感。像我们这样的哺乳动物已经进化出了保持体温相当恒定的方法，这确保了我们的细胞能够充分发挥作用。然而，在发烧期间，我们的体温会上升，而在冬眠期间，动物允许他们的温度下降到非常低的水平，所以即使是哺乳动物，他们的温度也有很大的变化。尽管几百年来我们就已经知道温度对生命的重要性，但温度是如何被感知的还不是很清楚。植物往往无法阻止温度的大幅波动，它们已经进化出非常复杂的方法来测量温度，并调整细胞的行为以适应这些变化。因此，植物是研究高等(非细菌)生物如何感知温度的完美系统。我们已经发现，当温度变化时，植物实际上会改变它们DNA的包裹方式。当温度升高时，植物DNA会变得不那么紧密。这使得基因可以随着温度的变化而开启。我们不知道的是，这是温度对DNA的直接影响，还是更间接的影响。在这项研究中，我们将确定这种变化如何控制的机制，并看看其他高等生物，如酵母和哺乳动物是否以同样的方式对温度做出反应。了解温度是如何被感知的很重要，因为它将帮助我们培育出对气候变化具有弹性的作物。较高的温度对作物产量尤其有害，因为它们会导致作物产量减少，从而使作物的品质变差。例如，在2003年炎热的夏季，法国的小麦产量下降了约20%。我们研究的目的是了解温度是如何被感知得足够好的，以便我们能够培育出具有改进的温度传感特性的植物。这样，就有可能培育出能够更好地应对气候变化的作物。农作物已经被培育了数千年，并被挑选出来对温度有非常敏感的反应。虽然这通常是一件好事，但有时，例如在发育中的谷物中，它会对作物产量产生不利影响。如果我们完全了解导致植物感知温度的分子，我们将能够改变植物不同部分对温度的感知和反应方式。这将是非常有价值的，因为温度变化是农业减产的一个主要原因。此外，气候变化正在增加温度冲击的严重性和频率。温度可以以许多不同的方式影响作物，例如通过改变开花时间来干扰作物的调度。一些作物也会因为温度变化而不适当地开花(例如生菜)。小麦和水稻在灌浆过程中对高温特别敏感。能够培育出具有最佳温度反应的作物，将使农民能够在更高和更多变的温度下可靠地种植作物。这对可持续性(农作物损失减少，产量得以挽救)和粮食安全至关重要，在一个拥有90亿人口的世界里，这一点尤为重要。

All living things are sensitive to their temperature. Mammals like ourselves have evolved ways to keep their body temperature fairly constant, and this ensures that our cells can work at their full efficiency. During fever though, our body temperature rises, and during hibernation, animals allow their temperature to drop to very low levels, so even mammals have significant variation in their temperature. Although we have known how important temperature is for life for hundreds of years, how temperature is sensed is not clearly understood. Plants often cannot prevent large fluctuations in their temperature, and they have evolved very sophisticated ways to measure temperature, and adjust the behaviour of their cells to adapt to these changes. Plants are therefore a perfect system to study how higher (non-bacterial) organisms sense temperature. We have found that plants actually change the way their DNA is wrapped when the temperature changes. When temperature increases, plant DNA becomes less tightly packed. This allows genes to be switched on in response to temperature. What we do not know is whether this is a direct effect of temperature on DNA, or is more indirect. In this study, we will determine the mechanism of how this change is controlled, and see if other higher organisms, such as yeast and mammals respond to temperature in the same way. Understanding how temperature is sensed is important because it will help us to create crops that are resilient to climate change. Higher temperatures are particularly damaging to crop yields since they cause the plant to make less grain which is of a poorer quality. For example during the hot summer of 2003, wheat yields in France decreased by about 20 %. The aim of our research is to understand how temperature is sensed well enough that we can breed plants with improved temperature sensing characteristics. In this way it may be possible to create crops that are better able to cope with climate change. Crops have been bred for thousands of years and selected to have a very sensitive response to temperature. While this is normally a good thing, sometimes, for example in the developing grain, it has bad effects on crop yields. If we fully understand the molecules that cause a plant to sense temperature we will be able to alter how different parts of the plant sense and respond to temperature. This would be very valuable, since variation in temperature is a major cause of lost yield in agriculture. Moreover climate change is increasing the severity of temperature shocks, as well as their frequency. Temperature can affect crops in many different ways, for example interfering with crop scheduling by changing flowering time. Some crops are also induced to flower inappropriately (for example lettuces) by temperature changes. Wheat and rice are particularly sensitive to high temperatures during grain filling. Being able to breed crops with optimal temperature responses would enable farmers to be able to grow crops reliably in the face of higher and more variable temperatures. This will be important for sustainability (fewer crops will be lost and yields will be saved) and food security, which will be particularly important in a world of 9 billion people.