SEEING SIGNALS: To determine whether a cell is secreting AHL signaling molecules, scientists can purify cell extracts, then separate the AHLs using thin-layer chromatography. Here, AHL molecules alone were run in lane 1 as a control, extracts of Yersinia pseudotuberculosis bacteria in lane 2, and mutants of the bacteria in lanes 3 and 4.COURTESY OF CHIEN-YI CHANG AND PAUL WILLIAMS
To infiltrate the defenses of a bacterial colony, a scientist needs to think a bit like a CIA agent. How are cells coordinating their activities? Which bacteria are sending messages to their neighbors, and what are they saying? Since the discovery more than 40 years ago that bacteria use chemical signals to communicate with each other and synchronize their behaviors, biologists have been trying to decode the molecular language of so-called quorum sensing.
Scientists now know that quorum sensing is a fundamental ability of many single-celled organisms. It allows bacteria to perceive the presence of neighbors, detect when they’ve reached a threshold number, and change their behavior in response—producing a toxin or altering their growth pattern, for instance. Pathogenic bacteria use quorum sensing to form ...
