Fig. 2. derrière induces both dorsal and ventral markers of mesoderm in whole embryos. Embryos were injected with 200 pg of derrière (der) mRNA into a single blastomere at the four-cell stage. Injections were targeted to either the dorsal (dor) or ventral (vent) marginal zone and gastrula stage embryos were analyzed by whole-mount in situ hybridization. (A-F) Embryos viewed from the side of injection. (A-C) Expression of the mesodermal marker xbra is induced on the side of injection. (D-F) Dorsal injection leads to expanded gsc expression, while ventral injection causes no ectopic expression of gsc in the ventral marginal zone. (G-I) Embryos viewed from the vegetal pole with dorsal facing rightwards. Ventral injection of derrière mRNA leads to increased expression of the ventral and lateral marker xvent1, while dorsal injection has no effect.
