Forgot your password?
Model Description (Tyson et al., 1999)
The self-feedback regulation model containing only the per mRNA and protein. Although having almost the same trough position, rapid rise in the mRNA concentration level introduces a time lag between the mRNA and protein peaks.
ABSTRACT
Many organisms display rhythms of physiology and behavior that are entrained to the 24-h cycle of light and darkness prevailing on Earth. Under constant conditions of illumination and temperature, these internal biological rhythms persist with a period close to 1 day ("circadian"), but it is usually not exactly 24 h. Recent discoveries have uncovered stunning similarities among the molecular circuitries of circadian clocks in mice, fruit flies, and bread molds. A consensus picture is coming into focus around two proteins (called PER and TIM in fruit flies), which dimerize and then inhibit transcription of their own genes. Although this picture seems to confirm a venerable model of circadian rhythms based on time-delayed negative feedback, we suggest that just as crucial to the circadian oscillator is a positive feedback loop based on stabilization of PER upon dimerization. These ideas can be expressed in simple mathematical form (phase plane portraits), and the model accounts naturally for several hallmarks of circadian rhythms, including temperature compensation and the per(L) mutant phenotype. In addition, the model suggests how an endogenous circadian oscillator could have evolved from a more primitive, light-activated switch.
Reference :
Tyson, J. J., Hong, C. I., Thron, C. D., and Novak, B. (1999).
" A simple model of circadian rhythms based on dimerization and proteolysis of PER and TIM. "
Biophys J 77, 2411-2417.
PubMed ID : 10545344
Model :
Zipped by E-Cell SE 3 >> [ Download ]
Zipped by SBML >> [ Download ]
