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Fig. 3. c-Jun (AP-1) leads to ectopic BMP-4 expression and to embryos showing a posteriorized phenotype. In situ whole-mount hybridizations demonstrate dorsal activation of BMP-4 upon injection of 500 pg AP-1 RNA (B) or 1 ng c-Jun (C) into both dorsal blastomeres of four-cell stage embryos; an uninjected control is shown in (A). While c-Jun transcripts are not detected within gastrula stage embryos (D), injection of 400 pg BMP-4 RNA into both dorsal blastomeres of four-cell stage embryos leads to a weak but distinct activation of the c-Jun gene (E). Injection of 1.5 ng c-Jun RNA into dorsal blastomeres suppresses head formation and causes a posteriorized phenotype (insert shows a control embryo at reduced size) (F). All embryos are photographed with dorsal side (top) and ventral side (bottom). |
