Fig. 2. BMP signaling in ectodermal cells regulates erythropoiesis. (Top) Two dorsal animal pole (A1) blastomeres of 32-cell embryos were injected with ß-gal RNA alone or together with dominant negative (tBR) or constitutively active (caALK3) BMP receptor RNAs as illustrated. (A) Tailbud stage 32 embryos were stained for ß-gal activity (red stain, white arrows) and then for globin RNA (purple stain, black arrows) by in situ hybridization. (B) Control embryos (ß-gal), as well as embryos in which BMP signaling was misregulated in A4 or A1 blastomeres, were analyzed for expression of globin by northern blot hybridization. Levels of globin transcripts, normalized relative to levels of EF-1
transcripts, are expressed as a percentage of control, below each lane.
