Fig. 3

gfi1aa regulates the primitive wave of zebrafish hematopoiesis. (A) gfi morphants and matching controls were subjected to WISH and analyzed for ICM expression (arrowhead) of primitive hematopoietic markers at the 20 ss. (a–f) ICM expression of the early hematopoietic markers, lmo2 and gata2, is preserved in gfi morphants and controls. (g–l) gfi1aa morphants show a reduction in ICM expression of scl and gata1, markers of primitive hematopoietic progenitors as compared to controls. Loss of gfi1b does not affect scl or gata1 expression in primitive hematopoiesis (c, f, i, l). (m–o) Loss of gfi1aa shows an expansion in the population of pu.1 myeloid progenitors, while no change is observed in gfi1b morphants. (p–r) The mpo myeloid population is expanded in gfi1aa morphants. (B) Transgenic reporter fish for primitive wave hematopoietic progenitors were subjected to FACS analysis after morpholino-mediated knockdown. (a) FACS of Tg(gata1:eGFP) embryos at the 20 ss reveals a significant decrease in the population of erythroid progenitors in gfi1aa morphants relative to controls. Erythroid progenitors are unaffected in gfi1b morphants (mean±SE, t test, ^□p<0.05, n=3). (b) FACS of Tg (pu.1:eGFP) embryos at the 20 ss reveals a significant increase in the population of myeloid progenitors in gfi1aa morphants relative to controls. Myeloid progenitors are unaffected in gfi1b morphants (mean±SE, t test, ^□p<0.05, n=5).