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Fig. 2. Overexpression of cPRDC in X. laevis. (A) Embryos were injected at the 4-cell stage in the ventral marginal zone with 1 ng chick PRDC RNA and left to develop until early tadpole stages. All control embryos are in the left hand panel, and PRDC-injected in the right, asterisk indicates secondary axis. (i) Uninjected control embryo compared to PRDC-injected embryo which has a partial secondary axis (marked with an ). Embryos were analysed for a variety of anterior–posterior markers: Hoxb9 (ii), Krox20 (iii), Otx2 (iv), and Emx1 (v). Arrows in (ii) and (iii) show the Hoxb9 and Krox20 gene expression in the secondary axis. White arrows in (v) indicate the lack of Emx1 forebrain expression, whereas the black arrow shows the kidney expression of Emx1. (B) PRDC can inhibit Bmp4 and Bmp7 but not Wnt8, as demonstrated by the coinjection of PRDC with these genes and the analysis of their immediate downstream targets. PRDC blocked the induction of brachyury (Xbra) and epidermal keratin (EK) by Bmp4 and 7, but not the induction of Siamois (Sia) and Xenopus nodal related-3 (Xnr3) by Wnt8 (see arrows). cg, cement gland; ey, eye; fb, forebrain; hb, hindbrain; ki, kidney; mb, midbrain; nc, neural crest; r3, rhombomere 3; r5, rhombomere 5; sc, spinal cord. |
