Fig. 5. Induction of the GFP expression directed from gata1-HRD by GATA1 overexpression. (A) A successive-injection system for the gata1 mRNA and the GFP reporter constructs. Embryos that were injected with template DNA into a blastomere at early one-cell stage were again injected with the GATA1 mRNA together with tetramethyl-rhodamine dextran into a single blastomere at the two- to eight-cell stage. (B) Ectopic GFP expression in the GATA1 mRNA-injected embryo. Embryos were fixed at 15 hours and were flattened on the slides with dorsal side upwards after removing the yolk. Dorsal views of embryos with anterior towards the left that were injected with GATA1 mRNA plus tetramethyl-rhodamine dextran (top, thick arrows) or with only tetramethyl-rhodamine dextran (bottom, thin arrows). Pictures in the left, middle and right columns were taken using the GFP plus, green or both filters, respectively. Arrowheads indicate the GFP expression in the LPM. (C) Difference in GFP induction by GATA1 among various gata1 constructs. Values indicate the percentages of embryos that showed ectopic GFP expression after injecting both the GATA1 mRNA and GFP reporter constructs. The numbers of embryos observed for each construct are indicated in parentheses.