Craniofacial structures of <i>Xenopus laevis</i> tadpoles upon injection of <i>Hoxd1</i> mRNA or protein.

<p><b>a</b>: Schematic ventral view of an uninjected untreated control embryo. <b>b</b>: uninjected embryo. <b>c</b>: embryo injected with wild type GFP into the blastoecel at blastula stage. <b>d</b>: Embryo injected with <i>Hoxd1</i> mRNA at 4 cell stage. <b>e</b>: Embryo injected with recombinant HOXD1 protein into 4 cell stage embryo. <b>f</b>: injection of recombinant HOXD1 protein into the blastoecel. Please note that standard injection of Hoxd1 mRNA or its protein counterpart injection in the cytoplasm or in the extracellular matrix leads to similar phenotypes in <b>d, e</b> and <b>f</b>. The embryos are strongly posteriorised as shown by the reduction (or deletion) of anterior structures. These data strongly suggest that the Hoxd1 protein successfully crossed the cellular membranes and retained its function as it leads to a severe truncation of anterior cartilage structures. Infrarostrale (in), Meckel’s cartilage (me), palatoquadrate (pa), ceratohyale (ce), basibranchiale (ba), branchial arches (br), eye (ey), intestine (in). Each photo represents 10 identically treated embryos giving the same result.