POLYCHAETOID IS REQUIRED TO RESTRICT SEGREGATION OF SENSORY ORGAN PRECURSORS FROM PRONEURAL CLUSTERS IN DROSOPHILA

Reduction of wild-type activity of the polychaetoid (pyd) gene results in formation of extra mechanosensory bristles on the head and notum o f adult Drosophila. Loss of pyd function results in decreased ability to restrict sensory organ precursor (SOP) formation to a single cell p er proneural cluster. Although the initial proneural cluster pattern o f achaete expression is not altered in pyd mutants, extra cells within proneural dusters express the high levels of achaete characteristic o f SOPs. This observation suggests that pyd(+) functions as a negative regulator of achaete-scute complex expression within the proneural clu ster. Synergistic interactions between pyd and Notch, Delta and extram acrochaetae mutations support this model. We also demonstrate that pyd is required for normal eye development.