"Collaborative Research: Circadian Rhythms of Gene Expression in Cyanobacteria"

昼夜节律是生物体对其环境日常规律变化的一种适应。虽然人们对昼夜节律的形式特征已知很多，但几乎没有人知道这些节律是如何在生化水平上起作用的。这个项目是双重的。首先，将使用目前已知的表达昼夜节律的最简单的生物，即原核蓝藻。其次，将使用遗传工具来分析其机制。编码生物发光酶的报告基因已经连接到内源启动子上。这种结构不仅使这些蓝藻生物发光，而且发光符合昼夜节律的所有显著标准|这是迄今描述的第一个“人工”昼夜节律。这种独特的昼夜节律基因表达情况将被用来：(1)通过动作光谱识别参与时钟携带的光感受器；(2)分析生物钟调节这种“人工节奏”的控制途径；以及(3)寻找参与时钟中央机制的基因。使用一个简单的原核系统应该会加速对昼夜节律振荡器运行的细胞机制的识别。%大多数生物对光和暗的循环作出反应的生理机制还不是很清楚。植物通过开启和关闭某些基因来响应这些循环。通过基因操作，这些研究人员将一种发光酶基因引入到一种基因中，该基因由日常的光-暗周期启动。因此，在光照后，随着基因的启动，这些细菌将开始发光。这项新技术将使研究人员能够更好地了解生物体对明暗循环做出反应的生化遗传机制。

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 will be 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 prokaryotic system should accelerate the identification of cellular mechanisms by which circadian oscillators operate. %%% Most organisms respond to the cycles of light and dark by physiological mechanisms that are not well understood. Plants respond to these cycles by turning on and off certain genes. By genetic manipulation these investigators have introduce a light emitting enzyme gene into a gene that is turned on by a daily light-dark cycle. Thus after light exposure these bacteria will begin to glow as the gene is turned on. This novel technique will allow the investigators to better understand the biochemical genetic mechanisms by which organisms respond to light-dark cycles.