Fig. 2.

The distal CRM is required to rescue gastrulation and Eve cell specification defects. (A-C) In situ hybridization of cellularized wild-type embryos (stage 5) containing sna-gfp construct using a gfp riboprobe and alkaline phosphatase staining procedure. sna-gfp (A) and sna-gfp ΔProximal (B) constructs supported sharp lateral and posterior borders, whereas the sna-gfp ΔDistal (C) construct was weaker and exhibited expanded lateral and posterior boundaries. (D-I) Fluorescent in situ hybridizations of sna¹/sna¹⁸ mutant embryos using sim (red) and gfp (green) riboprobes to detect sna construct reporter expression and effects on gastrulation through assay of sim. sna mutant embryos containing either the full-length construct sna-gfp (D,G); the proximal delete construct sna-gfp ΔProximal (E,H); or the distal delete construct sna-gfp ΔDistal (F,I) are shown. (J-L) Eve expression in sna mutant germ-band elongated embryos containing sna-gfp (J), sna-gfp ΔProximal (K) or sna-gfp ΔDistal (L). Arrows indicate gaps in eve expression. (See Fig. S1 in the supplementary material for sna-gfp `D to P' and `squish images', also see Fig. S2 in the supplementary material for late Eve expression.)