Fig. 4.

Inhibition of BMP signaling impairs PAA progenitor specification. (A,A′) Transcripts of scl and etv2 were evaluated by in situ hybridization in DMSO- or DMH1-treated embryos. Embryos were treated with DMSO or 10 μM DMH1 from 24 to 38 hpf. Numbers indicate PAA angioblast clusters. The average numbers of scl⁺ and etv2⁺ PAA angioblast clusters are quantified in A′ based on three independent experiments and the group values are expressed as mean±s.d. Student's t-test, ***P<0.001. (B,C) Wild-type embryos were treated with DMSO or with 10 μM DMH1 within the indicated time windows. Subsequently, these embryos were harvested for in situ hybridization. The numbers indicate the PAAs (B) or PAA progenitor clusters (C). (D-E′) Ectopic induction of caBmpr1b rescues the defects of PAA progenitor specification and angioblast differentiation in the pouch-depleted embryos. Tg(nkx2.3:KalTA4-p2a-mCherry;UAS:NTR-mCherry;hsp70l:caBmpr1b-GFP) embryos were treated with 10 mM MTZ from bud stage, heat shocked at 24 hpf for 20 min, and then harvested at the indicated stages for in situ hybridizations with nkx2.5 (D) and etv2 (E) probes. The average numbers of etv2⁺ PAA angioblast clusters were quantified from three independent experiments (E′). Significance of differences compared with MTZ treatment group were analyzed with Student's t-test (*P<0.05; ***P<0.001).