DELTA AND SERRATE ARE REDUNDANT NOTCH LIGANDS REQUIRED FOR ASYMMETRICCELL DIVISIONS WITHIN THE DROSOPHILA SENSORY ORGAN LINEAGE

Asymmetric divisions allow a precursor to produce four distinct cells of a Drosophila sensory organ lineage (SOL). Whereas this process requ ires cell-cell communication via Notch (N) receptor, mitotic recombina tion that removes the N ligand Delta (Dl) or Serrate (Ser) in the SOL had mild or no effect. Removal of both Dl and Ser, however, led to cel l fate transformations similar to the N phenotype. Cell fate transform ation occurred even when a single SOL cell lost bath Dl and Ser. Thus, DI and Ser are redundant in mediating signaling between daughter cell s to specify their distinct cell fates.