Greene Andrew V, Keller Nancy, Haas Hubertus, Bell-Pedersen Deborah
Program in Biological Clocks, Department of Biology. Program in the Biology of Filamentous Fungi, Texas A&M University, College Station, Texas 77843, USA.
Eukaryot Cell. 2003 Apr;2(2):231-7. doi: 10.1128/EC.2.2.231-237.2003.
We have established the presence of a circadian clock in Aspergillus flavus and Aspergillus nidulans by morphological and molecular assays, respectively. In A. flavus, the clock regulates an easily assayable rhythm in the development of sclerotia, which are large survival structures produced by many fungi. This developmental rhythm exhibits all of the principal clock properties. The rhythm is maintained in constant environmental conditions with a period of 33 h at 30 degrees C, it can be entrained by environmental signals, and it is temperature compensated. This endogenous 33-h period is one of the longest natural circadian rhythms reported for any organism, and this likely contributes to some unique responses of the clock to environmental signals. In A. nidulans, no obvious rhythms in development are apparent. However, a free running and entrainable rhythm in the accumulation of gpdA mRNA (encoding glyceraldehyde-3-phosphate dehydrogenase) is observed, suggesting the presence of a circadian clock in this species. We are unable to identify an Aspergillus ortholog of frequency, a gene required for normal circadian rhythmicity in Neurospora crassa. Together, our data indicate the existence of an Aspergillus circadian clock, which has properties that differ from that of the well-described clock of N. crassa.
我们分别通过形态学和分子分析方法，证实了黄曲霉和构巢曲霉中存在昼夜节律钟。在黄曲霉中，该节律钟调控着菌核发育过程中一种易于检测的节律，菌核是许多真菌产生的大型存活结构。这种发育节律展现出了所有主要的生物钟特性。该节律在恒定环境条件下得以维持，在30摄氏度时周期为33小时，它能够被环境信号所诱导，并且具有温度补偿性。这种内源性的33小时周期是已报道的任何生物体中最长的自然昼夜节律之一，这可能导致了该生物钟对环境信号产生一些独特的反应。在构巢曲霉中，未观察到明显的发育节律。然而，观察到gpdA mRNA（编码甘油醛-3-磷酸脱氢酶）的积累存在自由运行且可诱导的节律，这表明该物种中存在昼夜节律钟。我们无法鉴定出与频率基因同源的曲霉基因，频率基因是粗糙脉孢菌正常昼夜节律所必需的。总之，我们的数据表明曲霉昼夜节律钟的存在，其特性与已充分描述的粗糙脉孢菌生物钟不同。
