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Flipping the Switch that Arms a Bacterium (4 of 4)

Caption: This is a fluorescent and light micrograph overlay showing the carcasses of three maternal nematodes containing infective juvenile stage nematode offspring and symbiotic bacteria (green). The maximum width of the carcasses ranges from 100-200 micrometers. Maternal nematodes acquire the symbiotic bacteria as a persistent biofilm on the posterior of the intestine. A minority of symbiont bacteria switch from the insect pathogenic form to a mutualistic form for transmission to nematodes. A single promoter inversion switches the symbiont between pathogenic and mutualistic states. This image relates to a paper that appeared in the July 6, 2012, issue of Science, published by AAAS. The paper, by V.S. Somvanshi at Michigan State University in East Lansing, Mich., and colleagues was titled, "A Single Promoter Inversion Switches Photorhabdus Between Pathogenic and Mutualistic States."

Credit: [Courtesy of Alexander Martin]

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