Fig. 7.

Osr1/Osr2 can repress bmp4 expression. (A) GR-mOsr1 RNA (750 pg) was injected into both dorsal-vegetal cells at the eight-cell stage and embryos were dexamethasone treated at stage 20 to induce the construct and analyzed at stage 34/35 for expression of the indicated genes. Insets show ventral views of wnt2b expression. (B) The X. laevis bmp4 promoter construct, showing two putative odd-skipped-binding sites. Green sequence indicates consensus odd skipped-binding site, red sequence is the exact bmp4 promoter sequence, and mutations to these sites are shown below indicated by ‘Δ’ and in black. (C) RNA (750 pg) encoding Xenopus, mouse or Drosophila Osr factors was co-injected with the –2123 bmp4: luciferase reporter at the 32-cell stage and luciferase activity was assayed at stage 12. Average relative activity ±s.d. (D) Xenopus Osr1 or Osr2 RNA (750 pg) was co-injected with the wild-type bmp4 reporter or the mutated reporter constructs indicated in B, and the resulting average fold repression ±s.d., of the luciferase reporter from three independent experiments was determined. ^*P<0.005.