Is that a fly in your leg?

Atantalizing finding from Gerard Campbell (University of Pittsburgh, Pittsburgh, PA) and Ibo Galindo, Juan Pablo Couso, and colleagues (University of Sussex, Brighton, UK) suggests that signaling pathways used in appendage development may be conserved between flies and mammals.

Until now, the fly and mammalian work had taken very different courses. Mammalian researchers concentrated on distal (i.e., near the fingers) FGF as a source of graded signals. But fly researchers felt that the key molecules were Wingless (Wg) and Decapentaplegic (Dpp), which are made in two stripes that intersect at the center of the area that will become a leg. (Fly larvae set up leg patterns in imaginal discs, flat layers of cells that later telescope out to form a limb.) Wg and Dpp act directly to turn on Distalless (Dll) and dachsund...