Fig. 8 LMO-2, SCL and GATA-1 act synergistically in animal pole explants to stimulate red blood cell production. (Top) Embryos were injected at the one-cell stage with CMV-driven plasmids encoding LMO-2, SCL and GATA-1 alone or in combination (100 pg). Animal caps were dissected at stage 8, treated with activin (100 pM) and collected for analysis at stage 33. Animal cap cells were enzymatically dissociated, stained with o-dianisidine and collected on glass slides in a cytocentrifuge. Hemoglobinzed cells (erythrocytes), stained brown with the chromogenic reagent, were counted on a bright field microscope. (Graph) Activin treatment of animal pole explants does not result in the formation of red blood cells (mock column, animal pole explants treated with activin from uninjected embryos). Expression of LMO-2, GATA-1 and SCL alone, or in tandem, gives rise to a moderate number of erythroid cells. Co-injection of LMO-2/GATA-1/SCL results in large numbers of o-dianisidine-positive cells in the embryonic explants.
