Figure 7.

The Su(H)-binding sites are required to repress sim transcription in the neuroectoderm. Lateral views of wild-type sim–lacZ (A,A′) or sim^mut–lacZ (B,B′) embryos showing the distribution of lacZ transcripts at stage 6. lacZ transcripts accumulated in a single row of mesectodermal cells in sim–lacZ embryos (A,A′). In contrast, they were detected in several rows of cells extending into the ventral neuroectoderm in sim^mut–lacZ embryos (B,B′; cf. A′ and B′). (A′,B′) Enlarged views of the embryos shown in A and B. These embryos are homozygous and express two copies of the transgene (A,A′,B,B′).