Courtesy of Alan Aderem
 BAR-CODED BACTERIA: Combined activation of Toll-Like Receptors (TLRs) produces different specific responses. In this example, Microbe 1 activates TLRs 4 and 5, and is therefore likely to be a Gram-negative, flagellated bacterium. Microbe 2 activates TLR 5 and TLR 2/6, and is therefore likely to be Gram-positive and flagellated. Because of slightly different specificities, Microbe 3 would elicit a different response.

Twas a head-scratcher: Twelve years ago, researchers found that a receptor, known for its role in a fruit fly dorsoventral patterning called Toll, was related to an important mammalian immune receptor called interleukin-1 (IL-1), a pro-inflammatory cytokine.1 "How could this be?" recalls biochemistry professor Luke O'Neill, Trinity College, Dublin. "We have IL-1, which is inflammatory, and Toll, which is developmental.... Why would they be so similar?" But then it was shown in the adult fly that Toll has a role in antifungal defense.2...

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