Unique Pattern of Gene Expression in the Erythroid Precursor Cells: gene expression/erythroid/CFU‐E/fetal liver

Erythroid cells were fractionated by preformed Percoll density gradient from livers of 12.5 day old mouse fetuses. With combination of lysing of mature erythroid cells, the CFU‐E (colony forming unit of erythroid) was enriched as high as 30% pure. The mRNA levels of the rt‐genes previously cloned as genes expressed in the reticulocytes are estimated in the fractionated erythroid cells. These rt‐genes show a drastic change in expression during erythroid differentiation; Their expression was not detectable at the CFU‐E cell stage. But it reached to maximum at the polychromatic erythroblast (stage I) and then decreases with maturation. The result suggests that mRNA synthesis of these rt‐genes may be induced after the stimulation of erythropoietin.