Collaborative Research: Circadian Rhythms of Gene Expression in Cyanobacteria

昼夜节律是生物体对其环境的有规律的日常变化的适应。尽管人们对昼夜节律的形式特性已经了解很多，这些特性使它们能够与每天的光/暗周期同步，但对这些节律在生化水平上的工作原理几乎一无所知。这个项目是双重的。首先，将使用目前已知表达昼夜节律的最简单的生物，即原核蓝藻。其次，利用遗传工具分析其机制。一个编码生物发光酶的报告基因被连接到一个内源性启动子上。这种结构不仅使这些蓝藻生物发光，而且这种发光符合昼夜节律的所有显着标准。这是迄今所描述的第一个“人工的”明显的生物钟节奏。这个独特的昼夜节律基因表达的案例被用来：(1)通过作用光谱学识别参与时钟干扰的光感受器；(2)分析生物钟调节这种“人工”节律的控制途径；(3)寻找与生物钟中心机制有关的基因。使用一个简单的细菌系统可以加速识别日常节律的细胞机制。戈登博士正在与范德比尔特大学的卡尔·约翰逊博士合作这个项目。

Circadian rhythms are an adaptation of organisms to the regular daily change of their environment. Although much is known about the formal properties of circadian rhythms which allow them to synchronize to the daily light/dark cycles, almost nothing is known about how these rhythms work on a biochemical level. This project is two-fold. First, the simplest organism now known to express circadian rhythms will be used namely, prokaryotic cyanobacteria. Second, genetic tools will be used to analyze its mechanism. A reporter gene encoding a bioluminescence enzyme has been attached to an endogenous promoter. Not only does this construct make these cyanobacteria bioluminescent, the glow meets all of the salient criteria of circadian rhythmicity. This is the first "artificial" overt rhythm of a circadian clock yet described. This unique case of circadian gene expression is being exploited to: (1) identify by action spectroscopy the photoreceptor involved in the clock's entrainment; (2) analyze the control pathway by which the circadian clock regulates this " artificial" rhythm; and (3) search for genes which are involved in the clock's central mechanism. %%% Using a simple bacterial system should accelerate the identification of cellular mechanisms by which daily rhythms. Dr. Golden is collaborating with Dr. Carl Johnson of Vanderbilt University on this project.