Studies on the DNA metabolism of erythroid cell. I. DNA level of erythroblastic nuclei of rabbit bone marrow, observation of normal, blood depleted, and phenylhydrazine anemias, and their recovery by red cell transfusion

For the purpose to reveal the changes in the metabolism of erythroblast in varied specialization stages the author observed the Feulgen DNA level of rabbit erythroblasts by microspectrophotometry. Observations were made on normal and anemic animals, and those receiving a mass red cell transfusion at the recovery stage of anemia where the early denucleation is stimulated. Observations have revealed that in normal erythropoiesis the DNA contents are kept at n to 2 n level from the proerythroblast to late basophilic stage, but in later stages, polychromatic and orthochromatic, DNA level per cell decreases gradually with advance of the cell specialization reaching the minimum level, nearly haploid level, at orthochromatic stage where most cells are believed to be denucleated. In blood depleted animals nearly the same pattern of DNA level was observed in connection with erythroid specialization as that in normal animal, except a relatively high DNA level in the later specialization. In the cases of the hemolytic anemia a similar tendency has been observed but the minimum level of DNA remains at a higher level, hypo-diploid level, in poly- and orthochromatic stages. Twenty-four hours after the mass red cell transfusion by which severe anemia has been recovered to the original level within one hour, the pattern of the DNA level of the erythroblast returns to the normal one showing a very low DNA level at the polyand the orthochromatic stages. The data indicate that the DNA synthesis of erythroblast kept at n to 2 n levels until the late basophilic stage begins to decline at polychromatic stage and reaches nearly haploid level at orthochromatic stage, but in active hemopoiesis the DNA synthesis is stimulated and the DNA contents are kept at a high level even in the late specialization stages, showing no relation between the denucleation and the low DNA level.