par Leloup, Jean-Christophe ;Gonze, Didier ;Goldbeter, Albert
Editeur scientifique Kriete, Andres;Eils, Roland
Référence Computational Systems Biology, Elsevier, Amsterdam, page (249-291)
Publication Publié, 2006
Partie d'ouvrage collectif
Résumé : This chapter explains how most living organisms have developed the capability of generating autonomously sustained oscillations with a period close to 24 hours. A first model for circadian oscillations in the Drosophila PER protein and its mRNA is based on multiple phosphorylation of PER and on the inhibition of per transcription by a phosphorylated form of the protein. Much as the PER model, the model based on the formation of the PER-TIM complex can account for sustained autonomous oscillations originating from negative auto-regulatory feedback. The lag after the L to D transition appears to be the same regardless of the duration of the light phase, because the level of TIM has decreased to a minimum value at the end of the L phase, and the time required for the PER-TIM complex to accumulate during the dark phase above the threshold for repression remains unchanged. The latter result stems from the fact that when TIM is already at its minimum a transient increase in TIM degradation remains without effect. © 2006 Copyright © 2006 Elsevier Inc. All rights reserved..