Retroelements Guide Adaptation

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Bordetella species, which cause respiratory infections in mammals, use a complex program of gene expression, mediated by the BvgAS phosphorelay, to change the cell surface and by extension infectivity. Bordetella bacteriophages use a diversity-generating system that changes receptor molecules for attachment and infection at specific frequencies. Thus BPP phage preferentially infect infectious, Bvg+ phase bacteria, BMP phage preferentially infect avirulent, Bvg-bacteria, and BIP are indiscriminate to bacterial phase. (From S. Doulatov et al., Nature, 431:476-81, Sept. 23, 2004.)

With inquisitive minds and tools as simple as a Waring blender, the work of early phage researchers such as Max Delbruck, Seymour Benzer, and Alfred Hershey generated much of the knowledge underlying contemporary molecular biology. But in a decision that echoes current debates about focusing too narrowly on canonical model organisms,1 Delbruck insisted that research be done only on the T-phages that infect Escherichia coli B. This and ...