Overexpression of scl, but not hoxa9a, increases gata1 in RA-treated embryos. Representative embryos are shown for each experiment. Similar results were observed in at least 2 other replicate experiments. (A-D). Single-cell embryos were injected with scl mRNA, then incubated in 10−6M RA from early gastrulation (60% epiboly) until mid somitogenesis (15 ss). Expression of gata1 was measured by whole-mount in situ hybridization after embryos were fixed at 15 ss. (E-H) Single-cell embryos were injected with hoxa9a mRNA and then incubated in 10−6M RA from early gastrulation (50% epiboly) until mid somitogenesis (12 ss). Expression of gata1 was measured by whole-mount in situ hybridization after embryos were fixed at 12 ss. Similar experiments incubating injected embryos in 10−6M RA from late gastrulation (90% epiboly) until mid somitogenesis (12-15 ss) showed comparable results.
