Figure 3.

Distinct regulatory roles of Ubx-VP16 on different target genes. (A and B) Expression of Antp in wild-type (A) and UAS-Ubx-VP16/arm-GAL4⁴ (B) embryos. Arrowheads indicate the ectopic expression of Antp in a few head segments after ubiquitous Ubx-VP16 expression (B). (C–F) Expression of Dll (C and D) and the Dll304-lacZ reporter (E and F) in wild-type (C and E) and UAS-Ubx-VP16/arm-GAL4⁴ (D and F) embryos. Expression of both Dll (D) and Dll304-lacZ (F) is partially repressed in thoracic segments, and weakly activated in a few ectopic epidermal positions (arrowheads), by Ubx-VP16. Antp and Dll transcripts were visualized by in situ hybridization with an Antp (A and B) or a Dll (C and D) antisense RNA probe; β-galactosidase was detected by immunostaining with a mouse monoclonal anti-β-galactosidase antibody (E and F). The position of the first thoracic segment primordia (T1) is indicated. Embryos are shown at stage 11 in lateral view. In embryos where UAS-Ubx-VP16 was expressed (B, D, and F) arm-GAL4⁴ was provided maternally.