Tokyo/Requirements

From 2007.igem.org

Abstract　　Concept & Model　　Requirements　　Genetic_circuit　　Works　　About_our_team

What is necessary for "Balanced differentiation"?

The most important and underlying point of our model is that the system is stable against environmental changes when two types of differentiated individuals coexist, called "Balanced differentiation." Our project have aimed at this "Balanced differentiation" but not dynamic equilibrium such as chemical ones.

To achieve this “Balanced differentiation", our model requires
1. bistability at two distinct states in a single cell
2. cell-cell communication by quarum sensing

Fig.1: Bistablity
Cells with the same gene take either of two states, A (worker, red) or B (idler, green) stably.

1. Bistability

~ at an individual level ~

For "balanced differentiation" in our model, two types of cells should coexist stably. Therefore, cells with THE SAME GENE SET need to take either of TWO DIFFERENTIATED STATES, A (Worker) or B (Idler) in our project as shown in Fig. 1. In order to distinguish from dynamic stability, "balanced differentiation" must be achieved by two distinct states inconvertible each other.

2. Cell-cell communication

When this balanced differentiation is disrupted, by removing all the A type for example, these individual cells sense the change. Their states A or B become unstable as if cells became upset - INDIVIDUAL STATES ARE UNSTABLE ⇒ They are COLLECTIVELY UNSTABLE. Then some of them changed their states while the others do not. As a result, at a certain ratio of A and B again, the whole system comes back to a stable states. Here the cells are COLLECTIVELY STABLE ⇒ INDIVIDUALS ARE STABLE under this balanced differentiation.

Fig.2: Cell-cell communication
Intercellular interaction is done by communication molecule AHL. When enough AHL is produced by the workers, the idlers are stable; however, if it is not ~ communication being interrupted, ~ they dedifferentiate. Thus, cells can sense the surrounding cell types.