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Fig. 2
Igf signaling is required for proper cardiomyocyte number in zebrafish embryonic hearts.
The number of ventricular cardiomyocytes (area encircled by dotted line) number decreased in embryos when Igf1r signaling was blocked. (A) Tg(myl7:nDsRed) single transgenic and (C) Tg(hsp:dnigf1ra-GFP; myl7:nDsRed) double transgenic embryos (n = 16) were heat shocked at 40°C for 30 min around 48 and 72 hpf and observed at 76 hpf. dnigf1ra embryos can be identified by GFP expression (C’ inset). Tg(myl7:nDsRed) single transgenic siblings (n = 16) were used as controls. myl7:nDsRed embryos were treated with Igf1r inhibitor (D) (n = 20) and DMSO as a control (B) (n = 20) from 48 to 72 hpf and observed at 76 hpf. a: atrium, v: ventricle. Scale bar = 20 μm. (E, F) Quantification of mean ventricular cardiomyocyte number ± S.E. (***p<0.0001; **p<0.001). Fewer ventricular cardiomyocytes were observed around 76 hpf after Igf1r signaling was blocked.