Apr. 5, 2013 — A person’s skin and a fruit fly’s exoskeleton, called a “cuticle” may not look alike, but both coverings protect against injury, infection, and dehydration. The top layers of mammalian skin and insect cuticle are mesh-works of macromolecules, the mammal version consisting mostly of keratin proteins and the fly version predominantly of the carbohydrate chitin. Yet the requirement of an outer boundary for protection is so ancient that the outermost cells of both organisms respond to some of the same signals. And because of these signaling similarities, the fruit fly Drosophila melanogaster serves as a model for wound healing.