Synthetic biology: Division of logic labour.

Cellular compartmentalization is an effective way to build gene circuits capable of complex logic operations, in which binary inputs are converted into binary outputs according to user-defined rules. See Letters p.207 & p.212 For the creativity of synthetic biologists to be unleashed, basic circuits must become truly interchangeable — that is, modular and scalable. Two papers in this week's Nature take steps towards that goal — one from the Escherichia coli camp and the other using yeast. Tamsir et al. harness bacterial 'quorum sensing' in E. coli and Regot et al. exploit yeast pheromone communication to achieve complex computation through communication between individual cells performing simple logic functions. Such extracellular 'chemical wiring' is one promising way to get around the difficulty of insulating different genetic circuits when these operate within a single cell.