Jc. Leloup et A. Goldbeter, A molecular explanation for the long-term suppression of circadian rhythmsby a single light pulse, AM J P-REG, 280(4), 2001, pp. R1206-R1212
Citations number
36
Categorie Soggetti
Physiology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
With the use of a molecular model for circadian rhythms in Drosophila based
on transcriptional regulation, we show how a single, critical pulse of lig
ht can permanently suppress circadian rhythmicity, whereas a second light p
ulse can restore the abolished rhythm. The phenomena occur via the pulsatil
e induction of either protein degradation or gene expression in conditions
in which a stable steady state coexists with stable circadian oscillations
of the limit cycle type. The model indicates that suppression by a light pu
lse can only be accounted for by assuming that the biochemical effects of s
uch a pulse much outlast its actual duration. We determine the characterist
ics of critical pulses suppressing the oscillations as a function of the ph
ase at which the rhythm is perturbed. The model predicts how the amplitude
and duration of the biochemical changes induced by critical pulses vary wit
h this phase. The results provide a molecular, dynamic explanation for the
long-term suppression of circadian rhythms observed in a variety of organis
ms in response to a single light pulse and for the subsequent restoration o
f the rhythms by a second light pulse.