Circadian rhythms in Neurospora crassa: farnesol or geraniol allow expression of rhythmicity in the otherwise arrhythmic strains frq10, wc-1, and wc-2.
In Neurospora crassa, the circadian rhythm can be seen in the bd (band) strain as a series of "bands" or conidiation (spore-forming) regions on the surface of an agar medium. Certain mutations at 3 different genes (frq, wc-1, or wc-2) lead to the loss of the circadian rhythm. In this study, it was found that the addition of 10(-4) to 10(-5) M of geraniol or farnesol restored rhythmic banding to strains that lack a circadian rhythm due to mutations in any 1 of these 3 genes. These 3 conditionally arrhythmic strains now exhibited robust, free-running conidiation rhythms. Their rhythms were neither temperature-compensated nor obviously sensitive to light, so the full properties of a circadian rhythm were not restored. At 20 degrees C, in growth tubes, farnesol treatment gave periods of 28, 26, and 22 h for the frq10, wc-1, and wc-2 strains, respectively. Geraniol treatment at 20 degrees C gave periods of 23, 25.5, and 24.5 h for the frq10, wc-1, and wc-2 strains, respectively. A PRC for temperature pulses (1 h, 20 to 40 degrees C) for the frq10 strain grown in the presence of geraniol showed strong resetting (type 0), suggesting that a temperature-sensitive oscillator was present. Farnesol and geraniol are related to known intermediates in the steroid (or mevalonate) pathway. These data are interpreted in terms of a 2-oscillator model, in which farnesol/geraniol activate or amplify a remaining oscillator (a postulated frq-less oscillator).
Granshaw
Tabitha
T
Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Tsukamoto
Michelle
M
Brody
Stuart
S
D000204:Activity Cycles / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000080462:Acyclic Monoterpenes; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000235:genetics*; D005204:Farnesol / Q000494:pharmacology*; D005656:Fungal Proteins / Q000235:genetics*; D008027:Light; D009492:Neurospora crassa / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D017354:Point Mutation / Q000235:genetics; D013696:Temperature; D013729:Terpenes / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics*
D000080462:Acyclic Monoterpenes; D004268:DNA-Binding Proteins; C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D013729:Terpenes; D014157:Transcription Factors; C105589:wc-1 protein, Neurospora crassa; C103772:white collar 2 protein, Neurospora; D005204:Farnesol; C007836:geraniol