Rescue of the Gata1.05 mutant by the βLCR-G1 transgene. (A) Rescue of G1.05 fetuses by the βLCR-G1 transgene (line B) at E12.5. Top panel: E12.5 fetuses of genotypes indicated; bottom panel: their fetal livers. (B) Flow cytometric analysis of the percentage of enucleated (FSC^low TER119⁺) erythroid cells in WT, βLCR-G1, βLCR-G1::G1.05:Y, and βLCR-G1::G1KO:Y E12.5 fetal livers cells after 2 days in hanging drop cultures. Enucleation was determined by cell size (FSC^low). Significant difference: *, P < .05; **, P < .002, compared with WT (unpaired t test). (C) βLCR-G1::G1.05:Y pup and wild-type littermate 11 days after birth; anemia is evident as pallor of the tail (arrow). (D) Peripheral blood of βLCR-G1::G1.05:Y pup and wild-type littermate; original magnification, 40×. (E) Flow cytometric analysis of bone marrow (top panel) and spleen (bottom panel) of βLCR-G1::G1.05:Y pup and wild-type littermate. Percentages of cells expressing CD71 and/or TER119 are indicated.