The Wieschaus Lab is interested in the patterning that occurs in the early Drosophila embryo. Most of the gene products used by the embryo at these stages are already present in the unfertilized egg and were produced by maternal transcription during oogenesis. A small number of gene products, however, are supplied by transcription in the embryo itself. We have focused on these "zygotically" active genes because we believe the temporal and spatial pattern of their transcription may provide the triggers controlling the normal sequence of embryonic development.