Fig. 7

Fig. 7 FGF regulates chordin expression but does not require Chordin to repress BMP transcript levels. Addition of AP20187 to iFGFR-1-injected embryos induces chordin expression (B) throughout the embryo while in the absence of AP20187 iFGFR-1 embryos maintain wild-type levels of chordin (A) at shield stage (early gastrula). Microinjection of 125 pg XFD mRNA has the opposite effect and dramatically reduces chordin expression at shield stage (D) compared to control-injected embryos (C). Whole mount RNA in situ hybridization of embryos from a dino heterozygote intercross (E–L). bmp2 expression at shield stage in iFGFR-1-injected embryos (E–H) exposed to AP20187 (G and H) or embryo water (E and F). The dino mutation does not suppress the activity of iFGFR-1 to repress bmp transcript levels. Genotypes of embryos are indicated. (I–L) bmp4 expression at shield stage in control (I and J) or embryos injected with 50 pg fgf3 mRNA-injected embryos (K and L). All views are animal pole. Genotypes of embryos were determined by PCR-based genotyping following photography. To determine if chordin has an effect on BMP transcript levels, real-time PCR was performed on embryos injected with 100 pg chordin and collected at 30% epiboly (M). Graphed is the fold change (y-axis) for bmp2, bmp4 and bmp7 levels relative to control injected embryos. These results show that chordin overexpression does not impact BMP transcript levels during the blastula period.