Enhanced erythropoiesis in Smap1–/– mice with MDS (ID no.
47; see Table 3). (A and G) Flow cytometry analyses of (A) bone marrow cells and (G) splenocytes prepared from Smap1+/+ and Smap1–/– mice. The cells were stained for indicated hematopoietic lineage markers. The numbers represent percentages of cells in each gated box. Flow cytometry analyses were performed for all Smap1–/– mice with MDS, and reproducible results were obtained. (B–F) Histology of spleens. (B) A macroscopic view of the spleen. Note the enlargement of the Smap1–/– spleen. (C and D) Sections were stained by hematoxylin and eosin. Note the enrichment of cells with densely stained nuclei in the red pulp of the targeted spleen. (E and F) Smears of Giemsa-stained splenocytes. Erythroblasts with densely stained nuclei are evident in the Smap1–/– smear. Scale bar: 10 μm. (H) CFU-C assay of bone marrow cells. Cells from wild-type and Smap1–/– mice were assayed in vitro for their CFU-C activity. The numbers of colonies were counted under a microscope, and the morphology was classified as shown. Triplicate cultures were prepared from each mouse, and 4 independent pairs of older than 1 year Smap1+/+ and Smap1–/– mice were used. The panel shows the averages ± SD of CFU-C values obtained from 12 cultures from each genotype. *P < 0.0. (I) Estimation of replicating cells in the spleen. Splenocytes from Smap1+/+ and Smap1–/– mice were processed for flow cytometry analysis of GATA1 and TOPRO3. 2N and 4N represent the diploid and tetraploid status of chromatin.