Logic of gene regulatory networks.

Regulatory networks of transcription factors and signaling molecules lie at the heart of development. Their architecture implements logic functions whose execution propels cells from one regulatory state to the next, thus driving development forward. As an example of a subcircuit that translates transcriptional input into developmental output, we consider a particularly simple case, the regulatory processes underlying pigment cell formation in sea urchin embryos. The regulatory events in this process can be represented as elementary logic functions.