SPATIALLY RESTRICTED EXPRESSION OF PIPE IN THE DROSOPHILA EGG CHAMBERDEFINES EMBRYONIC DORSAL-VENTRAL POLARITY

Expression of pipe in the somatic tissue of the Drosophila ovary is re quired for the formation of embryonic dorsal-ventral polarity. pipe, w hich encodes an enzyme similar to the glycosaminoglycan-modifying enzy me heparan sulfate 2-O-sulfotransferase, is expressed in a spatially r estricted domain of follicle cells on the Ventral side of the egg cham ber. Mutations that affect follicular polarity correspondingly alter t he spatial pattern of pipe expression. Directed expression of pipe in otherwise pipe mutant females restores embryonic lateral and ventral p attern elements and can orient the dorsal-ventral axis of the embryo. Thus, the localized expression of pipe and the spatially restricted mo dification of carbohydrate chains play pivotal roles in the mechanisms that establish embryonic pattern and integrate follicular and embryon ic polarity.