Circadian clocks are autonomous timers that are believed to confer organisms a selective advantage by enabling processes to occur at appropriate times of the day. In the model fungus Neurospora crassa, 20-40 % of its genes are reported to be under circadian regulation, as assayed in simple sugar media. Although it has been well-described that Neurospora efficiently deconstructs plant cell wall components, little is known regarding the status of the clock when Neurospora grows on cellulosic material, or whether such a clock has an impact on any of the genes involved in this process. Through luciferase-based reporters and fluorescent detection assays, we show that a clock is functioning when Neurospora grows on cellulose-containing wheat straw as the only carbon and nitrogen source. Additionally, we found that the major cellobiohydrolase encoding gene involved in plant cell wall deconstruction, cbh-1, is rhythmically regulated by the Neurospora clock, in a manner that depends on cellulose concentration and on the transcription factor CRE-1, known as a key player in carbon-catabolite repression in this fungus. Our findings are a step towards a more comprehensive understanding on how clock regulation modulates cellulose degradation, and thus Neurospora's physiology.

中文翻译：

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粗糙脉孢菌中的生物钟在植物细胞壁解构过程中发挥作用

生物钟是自主计时器，被认为通过使过程在一天中的适当时间发生，从而赋予生物体选择性优势。在模型真菌粗糙脉孢菌中，据报道其 20-40% 的基因受昼夜节律调节，如在单糖培养基中测定的。尽管已经很好地描述了脉孢菌有效地解构植物细胞壁成分，但对于脉孢菌在纤维素材料上生长时的时钟状态，或者这种时钟是否对参与该过程的任何基因有影响，我们知之甚少。通过基于荧光素酶的报告基因和荧光检测分析，我们表明，当脉孢菌在作为唯一碳和氮源的含纤维素麦秆上生长时，时钟正在发挥作用。此外，我们发现参与植物细胞壁解构的主要纤维二糖水解酶编码基因 cbh-1 受脉孢菌钟有节奏地调节，其方式取决于纤维素浓度和转录因子 CRE-1，CRE-1 被称为这种真菌中的碳分解代谢物抑制。我们的发现是朝着更全面地了解时钟调节如何调节纤维素降解以及脉孢菌的生理学迈出的一步。