A circadian oscillator in Aspergillus spp. regulates daily development and gene expression.
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.
Greene
Andrew V
AV
Program in Biological Clocks, Department of Biology. Program in the Biology of Filamentous Fungi, Texas A&M University, College Station, Texas 77843, USA.
Keller
Nancy
N
Haas
Hubertus
H
Bell-Pedersen
Deborah
D
D001230:Aspergillus / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D001231:Aspergillus flavus / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D001683:Biological Clocks / Q000235:genetics*; D002940:Circadian Rhythm / Q000235:genetics*; D004780:Environment, Controlled; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000096:biosynthesis / Q000235:genetics; D010775:Photic Stimulation; D012333:RNA, Messenger / Q000378:metabolism; D013696:Temperature
D012333:RNA, Messenger; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)