Figure 2.

Rescue of ventral and lateral development in embryos by injection of gd RNA. After injection, live embryos at the gastrulation stage (A, C, E, and G) or cuticles produced by the embryos (B, D, F, and H) were examined. Embryos are oriented anterior end to the left and dorsal side up. (A and B) Embryos lacking maternal gd develop the dorsalized phenotype, symmetric folds both dorsally and ventrally at gastrulation, and a cuticle lacking all ventral and lateral structures. (C and D) After injection with 0.03 mg/ml gd RNA, the majority of gd mutant embryos are completely rescued, as evident by the lateral head fold (*) and anterior-ward displacement of pole cells (arrowhead) from original posterior position. These embryos produce a normal dorsoventral cuticle pattern showing ventral denticles (inverted v) and the dorsolateral Filzkörper (arrow). (E and F) Injection of ≥0.75 mg/ml gd RNA causes gd mutant embryos to develop the ventralized phenotype, recognizable by head fold on dorsal side (*) and retention of pole cells at posterior. These embryos produce a cuticle showing mainly ventral denticles in a disorganized pattern. (G and H) After injection with ≥0.75 mg/ml gd RNA, embryos from a nudel or pipe mutant develop the lateralized phenotype, as evident by prominence of head fold both dorsally and ventrally (*). These embryos develop a cuticle pattern similar to the ventralized phenotype. Embryos from the nudel mutant were injected without prior removal of the outer eggshell layer. The bright structure surrounding the cuticles in B, F, and H is the inner eggshell layer.