Figure 1.

Expression pattern of Evi1 in hematopoietic cells and gross appearance of E9.5 Evi1^−/− embryos. (A) Quantitative RT–PCR analysis of Evi1 mRNA in hematopoietic cells from mouse embryos and adult bone marrow. The embryonic cells analyzed are CD45⁻Ter119⁺ primitive erythrocytes, CD45⁺Ter119⁻ hematopoietic cells other than primitive erythrocytes, CD45⁺c-Kit⁻CD34⁻ mature hematopoietic cells, a CD45⁺c-Kit⁺CD34⁺ HSC-enriched population and para-aortic splanchnopleura (P-Sp). The bone marrow cells analyzed are CD4⁺/CD8⁺, T cells; B220⁺, B cells; CD11b⁺, macrophages and monocytes; Gr-1⁺, granulocytes; Ter119⁺, erythrocytes; CD41⁺, megakaryocytes; CD45⁺Lin⁺, mature hematopoietic cells; CD45⁺Lin⁻, immature hematopoietic cells; c-Kit⁺Sca-1⁺Lin⁻, HSC-enriched population. A mixture of anti-Mac-1, -Gr-1, -B220, -CD4, -CD8 and -Ly-6 antibodies was used as a lineage marker (Lin). Evi1 mRNA was assayed by real-time PCR (Materials and methods). The data were normalized to GAPDH mRNA and calibrated to the Evi1/GAPDH ratio (ΔCT) in CD45⁻Ter119⁺ cells in mouse embryos and CD45⁺Lin⁺ in adult bone marrow. The data are the mean and standard deviation of 2^−ΔΔCt in triplicate assays. (B) (a) The yolk sac from Evi1^−/− embryos shows severe anemia and defective large vessel development, while large vessels developed and were organized in the yolk sac of Evi1^+/− (b) and wild-type embryos at E9.5 (c). (d–f) Gross appearance of Evi1^−/− (d), Evi1^+/−(e) and wild-type (d) embryos at E9.5. The Evi1^−/− embryo is smaller and much paler than the wild-type littermate, while also showing pericardial effusion and hemorrhaging.