Expression of human γ-globin in μLCR-Aγ⁺, EKLF^−/− embryos.

(A) Human γ-globin is highly expressed in the fetal livers of μLCR-Aγ⁺ transgenic animals. RNase protection for human γ-globin and murine α-globin transcripts in E15 fetal liver-derived erythroid cells. The presence of the transgene and the EKLF genotype, as determined by Southern blotting, is indicated above each lane. The specific activity of the human γ-globin probe was 10-fold greater than the murine α-globin probe. Migration of undigested murine α-globin and human γ-globin riboprobes is indicated by arrows. The protected mRNA species corresponding to murine α-globin and human γ-globin are indicated by arrowheads. (B) Human γ-globin protein was readily detectable by immunofluorescence in fetal liver cells of embryos harboring the μLCR-Aγ transgene. Cytocentrifuge preparations of E15 fetal liver cells from EKLF^−/− Aγ⁺ embryos were stained with a FITC-conjugated monoclonal antibody raised against HbF (see “Materials and Methods”). There was no detectable green fluorescence in a control sample of EKLF^−/−Aγ− fetal liver cells (not shown).