Premature TGF-β Signaling Induces Precocious Differentiation of tie1+ PAA Angioblasts
(A) Experimental design for heat-shock-mediated (HS+) induction of TGF-β signaling in Tg(hsp70:caAlk5) embryos at 14 hpf (10 somites stage) followed by analysis of etsrp+ and tie1+ PAA angioblasts at 24 or 28 hr post-fertilization (hpf), respectively. Transgenic embryos not exposed to heat shock (HS–, Tg+) and heat shocked wild-type embryos (HS+, Tg–) were used as controls.
(B–G) Left lateral images of 24-hpf (B–D) or 28-hpf (E–G) control (B, C, E, and F) and experimental (D and G) embryos. Two large etsrp+ or tie1+ PAA angioblast clusters are visible in (D) and (G), respectively, whereas the majority of control embryos (B, C, E, and F) lacked PAA angioblasts at this stage. Scale bars, 200 μm.
(H and I) Bar graphs showing the average number of etsrp+ or tie1+ angioblast clusters ±SD within each experimental group (∗p < 0.05; ∗∗p < 0.01). n = 40–50 embryos per group with a total of three biological replicates.