Movie 3

Ectopic endoderm induction via over-expression of Sox32. Z-stack through a Tg(cryaa:Venus; 5xC120:sox32); Tg(sox17:GFP) embryo at approximately 70% epiboly. The embryo was injected with H2B-mCherry mRNA to label all nuclei (red) and TAEL mRNA. At 3-4 hpf, the animal pole was illuminated with a 2 min pulse of blue light to activate TAEL-dependent sox32 expression. Images were acquired every 0.9 μm on a Nikon Ti-E microscope equipped with a Yokogawa CSU-22 spinning disk confocal unit. The z-stack starts at the embryo surface and goes through towards the yolk. Tg(sox17:GFP) expression (green) is apparent in the outermost cell layers as well as within the endogenous endoderm layer.