Molecular Mechanisms of Seasonal Time Measurement

项目概要/摘要 未能对季节变化作出反应会对生物体的生存能力造成严重后果， 繁殖。对于人类来说，周围环境的季节性波动，尤其是光照量， 可能导致季节性情感障碍，以及心血管和免疫相关疾病。动物中 而植物的繁殖则与特定的季节紧密相连。许多生物，包括人类， 进化的感知机制，通过调整体内平衡，生理学， 发展先行者的要求我们的研究计划的长期目标是阐明分子机制， 这种生物测量季节变化，特别是白天的长度和温度。虽然我们知道 外部刺激（光和温度）和内部生物钟之间的相互作用 季节性反应，所涉及的分子调控网络在很大程度上仍然难以捉摸。季节性时间 几十年来，测量一直是时间生物学的重要课题之一，我们已经了解到， 动物和植物中都存在类似类型或结构的这些网络。在模式生物中， 在本研究中，我们对模式植物拟南芥的了解是最先进的。在拟南芥中， 通过分子时钟网络处理环境光和温度差， 转录的成花素（花诱导）基因称为FLOWERLOCUS T（FT）。我们的重点是 阐明FT转录是如何被调节的。虽然生物钟依赖的季节感测 机制是FT表达的主要控制者，其他外部和内部信息被导入 调节FT转录以精确确定开花时间。在本建议的目标1中，我们 将在表达FT的细胞和 在组织/细胞类型水平上不表达FT。有了这些信息，我们将能够组织我们目前的 在整个植物水平上理解FT调节为更精确的组织/细胞类型特异性调节。 通过我们对自然界中生长的植物的研究，我们最近发现了一种受光控制的FT转录调节 和生物钟之间的联系，到目前为止还完全没有被描述出来。我们将研究 目标2中的这种调节机制。我们在季节感应机制方面的工作提供了 光感受器FKF1的功能知识。在目标3中，我们将获得关于 如何通过调整光激发态的长度和分析生物化学的变化来构建这种感光器 输出函数这些信息将帮助我们了解这种光感受器的光化学特征 控制功能输出;它也可能为我们提供更多的光遗传学工具。调查结果将有一个 对植物研究的巨大影响以及我们对季节感测和生物钟的更广泛理解， 哺乳动物和其他系统，包括人类。

PROJECT SUMMARY/ABSTRACT Failure to respond to seasonal change has severe consequences for an organism’s ability to survive and reproduce. For humans, seasonal oscillation in the surrounding environment, especially the amount of light, can cause Seasonal Affective Disorder, as well as cardiovascular and immunity-related diseases. In animals and plants, reproduction is precisely aligned with specific seasons. Many organisms, including humans, have evolved sensing mechanisms to prepare for upcoming seasonal changes by adjusting homeostasis, physiology and development. The long-term goal of our research program is to elucidate the molecular mechanisms by which organisms measure seasonal changes, particularity in day length and temperature. Although we know that the interplay between external stimuli (light and temperature) and the internal circadian clock orchestrates seasonal responses, the molecular regulatory networks involved have remained largely elusive. Seasonal time measurement has been one of the important topics in chronobiology for decades, and we have learned that similar types or structures of these networks exist in both animals and plants. Among the model organisms used in this research, our knowledge of the model plant Arabidopsis is the most advanced. In Arabidopsis, ambient light and temperature differences are processed through the molecular clock network to regulate the transcription of a florigen (flower-inducing) gene called FLOWERING LOCUS T (FT). Our major focus is elucidating how FT transcription is regulated. Although the circadian clock-dependent seasonal sensing mechanism is the major controller of FT expression, other external and internal information is channeled into the regulation of FT transcription to precisely determine the timing of flowering. In Aim 1 of this proposal, we will obtain more precise epigenomic and transcriptomic information in both FT-expressing cells and cells that do not express FT at the tissue/cell-type levels. With this information, we will be able to organize our current understanding of FT regulation at the whole plant level into more precise tissue/cell-type specific regulation. Through our study of plants grown in nature, we recently found an FT transcription regulation controlled by light and the circadian clock that had been completely uncharacterized up to this point. We will study the molecular mechanisms underlying this regulation in Aim 2. Our work in seasonal sensing mechanisms has provided functional knowledge about the photoreceptor FKF1. In Aim 3, we will obtain more precise knowledge about how this photoreceptor is built by tuning the length of light-excited states and analyzing changes in biochemical output function. This information will help us understand how the photochemical features of this photoreceptor control functional outputs; it will also likely provide us with more optogenetic tools. The findings will have a large impact on plant research and our broader understanding of seasonal sensing and circadian clocks in mammals and other systems, including humans.