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Fig. 8. FGFR and Hh signaling can collaborate in eye ventralization. (A) Embryos were unilaterally co-injected with 1 pg bhh mRNA and 0.5 pg iFGFR1 mRNA, and induced with AP20187 from stage 12.5/13, followed by molecular marker analysis at stage 33. Pax2 is mainly activated within the ventral half of the eye (class I eyes) by bhh alone, while in the presence of iFGFR1 and bhh Pax2 expression extends into the dorsal eye (class II and class III eyes). Co-injection of bhh and iFGFR1 mRNAs also slightly increases the frequency of eyes with ubiquitous Vax2 expression and more strongly represses Tbx5 when compared with bhh alone. Under these conditions, iFGFR1 mRNA alone has no obvious effect on Pax2, Vax2 and Tbx5 expression. (B) Quantification of the effects of bhh and iFGFR1 on Pax2, Vax2 and Tbx5 expression. Between 24 and 30 embryos were analyzed for each sample in these experiments. (C) Schematic representation of the results shown in A. In class II eyes, the expanded OS does not reach the most dorsal retina, which can acquire in part ventral identity. In class III eyes, the retina is mostly or completely transformed into OS. |
