Fig. 2

Reduced bmp expression but intact BMP signal transduction in p18ahub mutants.

(A–H) In situ hybridization on early gastrula stage embryos or equivalent, except (C) and (D) are mid gastrula stage or equivalent. Embryos were stage-matched. Animal pole views, dorsal to the right for all. Expression of bmp ligand gene in WT embryos (A, n = 32, C, n = 43, and E, n = 21) and p18ahub embryos (B, n = 30, D, n = 18, and F, n = 16). Expression of the BMP antagonist chordin (chd) was confined to the dorsal side of WT embryos (G, n = 21) but was expanded around the entire margin of p18ahub embryos (H, n = 20) by early gastrulation. (I–N) Pie charts indicate fractions of embryos at 24 hpf that displayed the indicated phenotypes (categories described in the text). Number of embryos is shown at the center of each chart. p18ahub embryos (I, O, uninjected) that were injected with 20 pg bmp2b mRNA were rescued to WT or ventralized (K, P, +bmp2b mRNA) similarly to WT embryos (J, +bmp2b mRNA). p18ahub mutant embryos (L, uninjected) depleted of Chordin, Noggin1, and Follistatin-like 2b proteins by MO injection were similarly ventralized (N, +MOcnf) to WT embryos (M, +MOcnf).