Complex spatio-temporal accumulation of alternative transcripts from the neurogenic gene Delta during Drosophila...

Delta (Dl) function is required for proper specification of epidermal and neural lineages within the neurogenic ectoderm of Drosophila melanogaster. We have determined the spatial accumulation of five Dl transcripts that arise as the result of alternative RNA processing during embryogenesis. We find that these transcripts accumulate in all cells of the neurogenic ectoderm immediately preceding neuroblast segregation, indicating that transcription of Dl does not differ between presumptive neuroblasts and presumptive dermoblasts. Dl transcripts also accumulate transiently in mesodermal and endodermal cells, suggesting that Dl may function in developmental processes in addition to differentiation of the neurogenic ectoderm. We find that three of the Dl transcripts are localized to the base of the nucleus during cellularization. The apparent association of these three transcripts with polysomes suggests that they accumulate within the cytoplasm at the nuclear periphery and is consistent with the hypothesis that Dl encodes multiple translational products.