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Fig. 7. Ras-dva1-mediated Fgf8 signaling induces expression of Agrs by upregulating Otx2.
(A-C) Otx2 is co-expressed with Ras-dva1 in cells of the outer layer of the anterior ectoderm. In situ hybridization on the left and right halves of the entire midneurula embryo and on sagittal vibratome sections was performed as described in the legends to Figs 1 and 2. (D,E) Inhibition of Fgf8 mRNA translation by an Fgf8 MO elicits partial inhibition of Otx2 expression and lateral and posterior expansion of the expression domain (red arrowheads). Yellow and black arrowheads indicate a reduction of high Otx2 expression in the presumptive midbrain and cement gland, respectively. (F,G,H,I) Inhibition of Otx2 mRNA translation by an Otx2 MO inhibits Xag and Ras-dva1 expression. (J,K,L,M) Co-injection of Fgf8a mRNA is unable to prevent the inhibitory influence of the Otx2 MO on Xag and Ras-dva1 expression. (N,O) Inhibition of Otx2 mRNA translation by the Otx2 MO inhibits Fgf8 expression (black arrows). (E′,G′,I′,K′,M′,O′) Fluorescent images of embryos shown in panels E,G,I,K,M,O demonstrate distribution of injected cells labeled by the co-injected FLD tracer. |
