Fig. S5

zic2a acts upstream of Fgf signaling and pax2a in OS development. (A-C) The expression of spry4, a direct target of Fgf signaling, after a 120-minute treatment with vehicle (A, normal in 13/13 embryos, n=2), a 30-minute treatment with SU5402 (B, strongly reduced in 10/10 embryos, n=2) and a 60-minute treatment with SU5402 (C, undetectable in 9/10 embryos, n=2). (D-F) zic2a expression after vehicle treatment for 120 minutes (D, normal in 16/16 embryos), after 30 minutes of SU5402 exposure (E, normal in 19/19 embryos) and after 60 minutes of SU5402 exposure (F, strongly reduced in the telencephalon, 2/17 embryos, but unaffected in the OS, 17/17 embryos). (G,H) zic2a expression at prim-5 after vehicle treatment starting at the tail bud (G, 25/25 embryos), or SU5402 treatment starting at the tail bud (H, absent in the telencephalon, 20/20 embryos, but normal in the OS). (I,J) zic2a is strongly expressed in the OS of both the wild-type (WT; I, 97/97 embryos, n=2) and in pax2a^-/- mutant siblings (J, 30/30 embryos, n=2). Arrows point to the telencephalon, arrowheads to the OS. Views are lateral, anterior to the left, except G′ and H′ that are ventral views, anterior to the left, of the embryos pictured in G and H. Embryos are shown at 16s (A-C), 19s (D-F) and prim-5 (G-H).