THE WINGLESS SIGNALING PATHWAY AND THE PATTERNING OF THE WING MARGIN IN DROSOPHILA

The margin of the wing of Drosophila is defined and patterned from a s tripe of cells expressing the wingless (wg) gene that is established d uring the third larval instar in the developing wing blade. The expres sion of the genes cut and achaete in a small domain in the prospective wing margin region reflects the activity of wg and probably mediate i ts function. Our results indicate that, in the wing margin, the wingle ss signal requires the activity of at least three genes: armadillo (ar m), dishevelled (dsh) and shaggy (sgg) and that the functional relatio nship between these genes and wg is the same as that which exist durin g the patterning of the larval epidermis. These observations indicate that arm, dsh and sgg encode elements of a unique 'wingless signalling pathway' that is used several times throughout development.