Gene Switches

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Fruit flies

During development, the fly's two wings grow from a structure in the larva known as the wing imaginal disk (top images). (An imago is an insect in its final, adult state.) The haltere grows from the larval haltere imaginal disk (bottom images). Remember the Ubx Hox gene? Using staining again, we can detect the gene product of Ubx. This reveals that the Ubx gene is naturally "off" in the wing disk—note the absence of the bright green stain in the upper right image—and is "on" in the haltere disk (lower right image). Now you'll see what happens when the Ubx gene—just one of a large number of Hox genes—is turned off in the haltere disk.

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