FIGURE 4.
Increased nucleated erythrocytes at midgestation of Gpr48-/- mice. A, blood smears from E13.5-E16.5 embryos were stained with Wright-Giemsa stain. Gpr48-/- embryos (right) of E13.5-E15.5 showed increased percentage of nucleated erythrocytes compared with the samples from their wild-type littermates (left), but no significant difference from E16.5 samples between Gpr48-/- and their wild-type littermates (magnification, 1000×). B, relative number in percentage of nucleated erythrocytes from blood smear slides. E13.5 and E14.5 Gpr48-/- embryos showed ∼2.5-fold and 1.8-fold increase in nucleated erythrocytes percentage compared with wild-type, respectively (p < 0.03). E12.5 and E16.5 littermates showed little differences in percentage of nucleated erythrocytes between wild-type and null embryos (p > 0.05). C and D, real-time PCR of embryonic hemoglobin chains (ζ, βh1, and εy) in E13.5 blood cell samples (C) and adult hemoglobin chains (α and β) in E13.5 livers (D). E, the cell size of erythrocytes was reduced by Gpr48 inactivation in E13.5 fetal livers. Ter119pos cells in Gpr48-/- mice bone marrow displayed a reduction in cell size compared with those in their wt littermates (x-axis represents the cell size). Green in the histogram represents Ter119-positive cells (mature red blood cells). Similar reduction of red blood cell size was observed from adult Gpr48-/- cells. However, the cell number did not show significant decrease in Gpr48-/- null mice.