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Fig. 3. FoxB1 cooperates with FGF signaling to promote neural development. (A–I) FoxB1 cooperates with eFGF to promote neural induction and posterior neural formation. Together with β-gal mRNA, GR-FoxB1 (250 pg) and eFGF mRNA (0.25 pg) were injected unilaterally into both dorsal and ventral animal blastomeres of 8-cell stage embryos as indicated. The expression of neural markers Sox2 (neural plate; A, D and G), En2 (midbrain–hindbrain boundary; B, E, and H), and HoxB9 (spinal cord; C, F and I) analyzed by in situ hybridization is shown in purple and β-gal is stained in red. The embryos injected with both GR-FoxB1 and eFGF mRNA displayed a more pronounced expansion of Sox2, En2 and HoxB9 expression (arrowheads in D, E and F, respectively), compared to embryos injected with either mRNA alone (A–C and G–I). The injected side of the embryo is indicated by brackets. All panels show dorsal views with posterior to the top, except for En2 (B, E, and H) where the anterior (front) view with dorsal to the top is shown. (J–L) Summary of phenotypes shown in (A)–(I). FoxB1 and eFGF cooperatively expand expression domains of Sox2 (J), En2 (K) and HoxB9 (L) genes. Each experiment was repeated more than twice and gave similar results. |
