Fig. S1

Hedgehog signaling and notochord differentiation are intact in MZtmem2 mutants. (A-D) In situ hybridization depicts expression of ptc1 at 24 hpf (A,C) or ehh at 30 hpf (B,D) in Mtmem2 (A,B) and MZtmem2 (C,D) siblings, lateral views, anterior at left. A′-D′ show closer views of regions outlined by white rectangles in A-D. (A,C) Expression of ptc1 serves as a reporter of Hedgehog signaling. Loss of Hedgehog signaling causes formation of U-shaped somites (Lewis et al., 1999; Schauerte et al., 1998; van Eeden et al., 1996), but Hedgehog signal transduction seems relatively robust in MZtmem2 mutants. (B,D) Notochord maturation is accompanied by loss of expression of ehh, a chordamesoderm marker (Parsons et al., 2002; Stemple, 2005). As notochord differentiation proceeds from anterior to posterior, ehh is visible only at the caudal end of the notochord by 30 hpf (B). The progression of differentiation is relatively normal in MZtmem2 mutants (D), although the slightly increased extent of ehh expression that remains at 30 hpf suggests a slight delay.