Induction of ectopic <i>chd</i> and <i>gsc</i> expression by dnSox3

<p><b>requires Fgf signalling.</b> Endogenous expression of <i>chd</i> and <i>gsc</i> (<b>A</b>,<b>B</b>) was inhibited by injection at 1–2 cell stage of a combination of morpholinos targeting both <i>fgf3</i> and <i>fgf8</i> (<b>C</b>,<b>D</b>), but these had little effect upon the ectopic expression of <i>chd</i> and <i>gsc</i> induced by injection of a dnSox3 construct (<b>E</b>,<b>F</b>). Treatment of embryos with the FGF signalling inhibitors, SU5402 (<b>I</b>,<b>J</b>) or MKP3 (<b>O</b>,<b>P</b>) (but not an equivalent concentration of the solvent DMSO alone) (<b>G</b>,<b>H</b>), at the 1–2 cell stage totally inhibited both endogenous expression of <i>chd</i> and <i>gsc</i> and ectopic expression induced by injection of a dnSox3 construct (<b>K–N</b>,<b>Q</b>,<b>R</b>). Lateral view and dorsal is to the right in upper panels, viewed from animal pole in lower panels. The proportion of embryos exhibiting these phenotypes is shown at the bottom right of each panel.