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Fig. 5. Ventral expression of SCL is blocked by a dominant negative BMP receptor but not by a dominant negative FGF receptor. (a,b) Expression of a dominant negative BMP receptor blocks SCL expression on the ventral axis. Embryos were injected at the two cell stage with 1 ng dnTFRII. Injected and uninjected sibling embryos were fixed at stage 32 and stained for SCL expression by in situ hybridization. SCL expression on the ventral axis (arrows) is ablated by injection of dominant negative BMP receptor mRNA.
(c) Expression of a dominant negative FGF receptor does not block ventral expression of SCL. Embryos were injected with mRNA encoding dominant negative FGF receptor (XFD; upper embryo; n=73) or a truncated mutant of XFD lacking part of the ligand binding domain (D50; lower embryo; n=51) (2.5 ng per blastomere at the two cell stage; Amaya et al., 1991). Embryos were fixed at the tailbud stage and analyzed for SCL expression by in situ hybridization. Although trunk and tail abnormalities exist, the SCL expression on the ventral axis (arrows) was not affected by over- expression of the dominant negative FGF receptor. |
