Fig. S2

Tg(sox10:Cre;cryaa:dsRed) expression relative to the developing heart. A-I) 15hpf, 19hpf and 22hpf embryos from the Tg(sox10:Cre;cryaa:dsRed) line were probed for myl7 and cre RNA detection by two color in-situ hybridization. myl7 was detected by FastRed staining (fluorescence in Red channel, magenta) and cre by NBT-BCIP stain (black). Arrows point to cre expression in the stereotypical neural crest lineage pattern progressing medially from the dorsal neural tube. Magenta arrow demonstrates the first detection of the myl7+ heart field in the ventral side of 22hpf embryos (low level magenta in A-D was equivalent to background and negative control stained embryos). A few black cre+ cells can be seen nearby the myl7 staining at this stage (black arrows). ‘h’= head region of embryo. Yolks were removed to mediate visualization. Scale bar = 100uM. Right panels are the ventral side images of the same embryos in left panels. G-I) Higher magnification of heart field, from red box shown in F. H and I show separate channels for cre and myl7, respectively. J-Q) 26hpf embryos from a cross of Tg(sox10:Cre;cryaa:dsRed) to the Tg(ubi:Switch) line were stained for MF20 and imaged for GFP, mCherry and MF20. The bottom panels are close up images of the heart area indicated by white dashed box in J. mCherry signal indicates the Cre switched neural crest cells. A few mCherry positive cells overlap with the MF20 heart marker indicating the first appearances of NC-Cms (white arrows). Scale bar = 75uM in prime labelled panels.