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Fig. 1
A Small-Molecule Screen in Zebrafish Implicates TGF-β Signaling in PAA Morphogenesis
(A) 1,235 small molecules were screened for activities that suppress the formation of tie1+ PAA angioblasts in zebrafish. Shown are the percentages of compounds that fell into each of three categories.
(B and C) Left lateral views of tie1+ PAA angioblast clusters in 36-hr post-fertilization (hpf) embryos treated from bud stage with DMSO (B) or 10 μM CB 41227199 (C), a predicted inhibitor of TGF-β signaling. The angioblast clusters are numbered as shown (B) according to the pharyngeal arches within which they form. Seven of 14 chemically treated embryos were devoid of tie1+ clusters.
(D–L) Left lateral views of (D–G) tie1+ or (I–L) kdrl+ PAA angioblasts in 36-hpf embryos treated from 20 hpf with DMSO or the indicated, increasing concentrations of LY-364947. The angioblast clusters that did form in LY-364947-treated embryos were smaller and/or failed to sprout (asterisks in F, G, K, and L). Scale bars, 200 μm.
(H and M) Bar graphs showing the average number of tie1+ or kdrl+ angioblast clusters ±SD that formed in each experimental group (∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001). n = 40–50 embryos per group with a total of three biological replicates.
(N–Q) Left lateral views of 60-hpf Tg(kdrl:GFP),Tg(gata1:DsRed) embryos treated from 20 hpf with DMSO (N) or LY-364947 (O and P) imaged in the green and red channels to visualize endothelium (pseudocolored magenta) and red blood cells (RBC) (pseudocolored yellow), respectively. In DMSO-treated embryos, four patent PAAs supported robust blood flow as evidenced by strong luminal RBC fluorescence (N). LY-364947-treated embryos displayed a reduced number (O; class I) or complete absence (P; class II) of patent PAAs. Asterisks in (P) highlight compensatory sprouting of endothelial cells from the LDA. (Q) Bar graph showing the percentages of DMSO (n = 30) and LY-36497-treated (n = 40) embryos with four patent PAAs (wild-type), one to two patent PAAs (class I), or zero PAAs (class II). ∗∗∗p < 0.001. No animals contained three patent PAAs. Scale bars, 25 μm.