WING DEVELOPMENT AND SPECIFICATION OF DORSAL CELL FATES IN THE ABSENCE OF APTEROUS IN DROSOPHILA

The development and patterning of the Drosophila wing relies on intera ctions between cell populations that have the anteroposterior (An) axi s and dorsoventral (DV) axis of the wing imaginal disc as frames of re ference [1-3], Each of these Cell populations gives rise to a compartm ent - a group of cells that have their fates restricted by cell lineag e within which cells acquire specific identities through the expressio n of 'selector' genes [1,2,4]. The genes engrailed (en) and invected ( inv), for example, label cells in the posterior compartment and mediat e a set of cell interactions that direct the patterning and growth of the wing along the AP axis [1,2,4]. A similar situation has been propo sed to exist across the DV axis, along with apterous (ap) as a dorsal selector gene [5], mediating cell interactions by regulating the expre ssion of Serrate (Ser) [6,7] and fringe (fng) [8], In ap mutants, the wing is last [5,9], and here we report that this phenotype can be resc ued by ectopic expression of either Ser or fng and that, surprisingly, the resulting wings have both dorsal and ventral cell fates.