Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): QscR, a Pseudomonas aeruginosa quorum-sensing regulator without a cognate signal generator responds to the LasI-generated signal. The images are agar plates streaked with a QscR mutant (left) and it's parent (right). The test tubes contain extracted phenazine pigments from the mutant and parent. The QscR mutant overproduces phenazine pigments. A single image is repeated multiple times to give the composite shown. (Original image produced by Sudha Chugani.) (See related article on page 3365.)