Team:Paris/Analysis/Model2 Analysis

Model Analysis

Bimodular system

Parameter search

In this system we rely on kinetic parameter values taken from the literature. However, three kinetic parameters remain unknown : HSL production rate, the threshold value of HSL above which EnvZ is expressed and the threshold value of EnvZ above which lasI is inhibited. We assume, as Ojalvo did, that this loop is functional and thus look for values of these three parameters such that concentration values of species in this loop oscillate.

For the HSL production rate we find that HSL time scale has to be similar to lasI time scale, that is the following is required : betaHSL/gammaHSLext =(betalasI/gamma)*(c) (TODO :latex) Besides we observe that the threshold value of EnvZ needs to be low and that the loop is functional for any threshold value of HSL. For three parameter values validating these requirements, the HSL loop alone has the following behavior :

Simulation of the HSL loop

We will use for all forthcoming use of the interactions appearing in this loop the parameter values deducted from this parameter search.

Coupling results

The two modules of the bimodular system are the the negative loop involving HSL, and the core system. These two modules are coupled by EnvZ. The HSL module is functional whereas the core system is not. We compare below the behavior of the core system alone to the behavior of the system coupling these two modules.

Simulaiton of the core system

Simulation of the bimodular system

Coupling these two modules has a positive effect on the overall behavior but it still does not provide sustained oscillations.

Unimodular system

Oscillations

Effect of auto activation loop. Effect of EnvZ threshold. It can provide oscillations as long as auto loop and threshold.

FIFO

FIFO behavior ok even without auto loop.

Synchronization

synchro ok (fct dilution eta)