Fig. 3.

Function of maternal and zygotic sFRP-1 during ANE restriction. A Compared to control embryos (a), embryos injected with sfrp-1 mRNA show expanded foxq2 expression (b). B In the absence of sFRP-1, foxq2 expression is completely eliminated from ANE territory (Bb), whereas sFRP-1 morphants co-injected with ΔFzl5/8 show expanded foxq2 expression (Bc). The number of embryos examined that show the representative phenotypes depicted is indicated in each panel. C A model diagram for ANE restriction during late blastula stages showing Wnt1/Wnt8–Fzl5/8–JNK signaling downregulates the transcription of fzl5/8 in posterior ectoderm, restricting its expression to the ANE territory. In the ANE, Fzl5/8 signaling activates dkk1 expression, antagonizing Wnt1/Wnt8–Fzl5/8–JNK signaling and establishing the ANE territory. Maternal and/or zygotic sFRP-1 is also necessary to antagonize Fzl5/8 signaling at this stage of development. The model is based data presented in this figure and from [20]. D Expression of foxq2 from 60-cell stage to mesenchyme blastula stage in control embryos (Da–e), in translation-blocking sFRP-1 morphants (Df–j) and splice-blocking sFRP-1 morphants (Dk–o). MO, morpholino. Scale bar = 20 μm