Gone are the days when bacteria were thought to just grow and divide and not bother to converse with one another. That simple idea has produced mountains of data and most of what we know about bacterial physiology is based on this notion. It turns out, as we know now, that this is an oversimplification. Lots more goes on in the life of bacteria, much of it dealing with communication with other cells. One widespread, if menacing-sounding, mode of communication consists of killing individuals of a population, apparently for the benefit of other of its members. A prevalent mechanism that accomplishes this is the toxin-antitoxin system for programmed cell death. Here, some seemingly altruistic cells are killed from within whereas others get dispatched after receiving extracellular signals. A lot is known about both mechanisms, this being a very active field of research. The signals involved are the subject of this piece.
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