Circadian adaptation dynamics of cyanobacterial genome

基于基因芯片分析结合分子遗传学，我们发现基因组上超过1/3的基因表现出明显的昼夜转录节律，在连续光照条件下，无论是主观的黎明还是黄昏，转录节律都达到峰值。当细胞转移到黑暗中时，大多数基因的表达被显著抑制，并导致转录和蛋白质组图谱之间的严重差异。此外，我们还发现，即使在黑暗中，基因组上也只有不到8%的基因被诱导，而且大多数基因都在KAI蛋白的控制下。由于KAI基因的mRNAs在黑暗中迅速丢失，我们的观察揭示了第一个没有从头时钟基因表达的时钟控制转录的例子。

Based on microarray analysis combined with molecular genetics, we revealed that more than one third of genes on the genome exhibit significant circadian transcription rhythms with peaking at either subjective dawn or dusk under continuous light conditions. When cells were transferred to the dark, most of gene expression was dramatically suppressed and gave rise to serious discrepancy between transcriptomic and proteomic profiles. Moreover, we found less than 8% of genes on the genome were induced even in the dark, and most of them were under the control of the Kai proteins. Since the kai gene mRNAs were rapidly lost in the dark, our observation revealed the first example of clock-controlled transcription without de novo clock gene expression.