IGEM:Harvard/2006/Brainstorming Papers - Jeffrey

Self organization

 * 1) so1 pmid=15858574
 * 2) so2 pmid=15096621

A synthetic multicellular system for programmed pattern formation.
 * Basu et al. created a gene circuit with a non-monotonic response to AHL concentration.
 * Main idea: use two concentration boundaries to define three regions with different transcriptional activity
 * GFP is repressed at low and high concentrations of AHL, and expressed at medium concentrations
 * Basu et al. created three variants with different upper boundaries
 * Concentration varies with distance; thus, a mixture of different variants of bacteria produces a bullseye pattern when exposed to a point source of AHL
 * Multiple AHL sources produce pretty pictures
 * We could reuse the basic idea behind their circuit if we need to define a multiple-region response to some stimulus

Spatiotemporal control of gene expression with pulse-generating networks
 * Basu et al. created a gene circuit that exhibits transient expression of GFP in response to AHL ("pulse generator").
 * The amplitude and duration of this "pulse" can be artificially adjusted, and depend on the rate of increase of AHL concentration as well as the absolute concentration.
 * Cells can be made to respond to nearby cells and ignore far-away cells
 * Reporter expression varies with distance, even though AHL concentrations eventually reach the same level everywhere
 * Further tweaking:
 * Produce AHL as well as expressing GFP, to propagate the AHL signal
 * Connect the output of the pulse generator to a bistable switch