Fig. 7. eFGF depletion, FRL1 and cmXnr2 overexpression increase Xnr3 induced convergent extension activity and gene expression. (A) Animal caps depleted of eFGF with 20 ng of eFGF morpholino (eFGF MO) were able to elongate in the presence of Xnr3 mRNA (right) and to express Xbra at the early gastrula stage (histogram). The experiment was repeated with the same result. (B) FRL1 acts synergistically with Xnr3. 500 pg of Xnr3 mRNA synergized with 500 pg FRL1 mRNA to cause excessive elongation of animal caps (left). RHS shows embryo injection experiments. 500 pg of FRL1 or 50 pg of Xnr3 mRNA injected into 2 ventral cells at the 8-cell stage did not cause finger-like protrusions in whole embryos. Injection of 50 pg Xnr3 mRNA together with 500 pg FRL1 mRNA caused extensive protrusion formation (arrowheads). (C) Animal caps taken from embryos exposed to secreted cmXnr2 as well as injected with Xnr3 mRNA, elongated significantly and showed a synergistic increase in the expression of Xbra and MyoD but not of goosecoid compared with Xnr3-overexpressing caps. Inset diagram shows that Xnr3 mRNA was injected animally at the two-cell stage, and cmXnr2 mRNA was injected into 4 vegetal cells, at the 8-cell stage. Caps were cut at the late blastula stage.