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Fig. 5. Xnr1 and Xnr2 act redundantly to control gastrulation but not mesendoderm induction. (A) Xenopus 4-cell embryos were injected in the two dorsal cells with 5 ng/cell of the indicated MOs, alone or in combination (2.5 ng each), together with 2.5 ng/cell FLDx. Embryos were fixed at stage 15 and processed for WISH and FLDx staining. Dorsal views, anterior to the top. Extending notochord (Xbra, Xnot-2) and prechordal mesoderm (goosecoid) were present but abnormally positioned. (B) DMZ was explanted at stage 10 from the same embryos as in A and cultured for 12 hours. For the purposes of rescue, 5 μg/ml recombinant Nodal protein was added to the culture medium after explantation. Elongation was significantly suppressed in double Xnr1/Xnr2 morphant explants, but was rescued by Nodal protein. (C) Head mesoderm was explanted at stage 10.25 from the same embryos as in A, plated on fibronectin-coated dishes and cultured for 3 hours. Spreading was severely impaired in double Xnr1/Xnr2 morphant explants, but was rescued in the presence of 5 μg/ml recombinant Nodal protein. |
