Why doesn ' t all the GTA get taken up?

I ' ve been modelling the production and uptake of GTA particles in a culture, hoping to understand the cause of thesurprising GTA-accumulation curve I described in the previous post.  But this has led me to a more fundamental surprise.Only a very small fraction of the cells in a GTA+ culture produce GTA particles and lyse, and all the other cells are able to bind GTA particles and take up their DNA.  So why doesn ' t all the new GTA quickly get taken up by all the surviving cells?Here are the basic principles I ' ve been assuming, based on what ' s in the literature: GTA production:  Cells in exponential growth don ' t produce GTA.  The GTA genes are turned on as the culture density gets high and growth slows.  Once the culture reaches its stationary-phase density GTA production stops. GTA uptake:  Cells in exponential growth express the capsule genes at a low level and bind GTA particles with moderate efficiency.  The capsule genes are turned up when culture density reaches a quorum-sensing threshold, and ability to bind GTA particles gradually increases.  Stationary phase cells bind GTA particles efficiently.  GTA decay:BTA particles are moderately unstable, so they fall apart with some unknown probability.Let ' s put some numbers to this:Assume that 1% of cells produce GTA over the course of the permissive stage.Assume that each producer cell produces 100 particles and then dies.Assume that each non-producer cell...
Source: RRResearch - Category: Molecular Biology Authors: Source Type: blogs