Variation of deoxyribonucleic acid polymerase activities during avian erythropoiesis.

Amounts of DNA polymerase alpha and beta were determined in extracts of chicken erythroid cells at various stages of development. Concentrations of both polymerase activities are high in erythroblasts which are still dividing, decline after the cells cease dividing and begin maturation, and become almost undetectable in the fully mature erythrocytes. While DNA polymerase alpha activity declines gradually, firmly bound DNA polymerase beta activity in the nuclei drops abruptly after the cells finish DNA synthesis and dividing. The amount of a low molecular weight DNA polymerase extractable with the cytoplasmic fraction, possibly DNA polymerase beta, is low in erythroblasts, increases in the more mature erythroid population and then declines to an undectable level in the fully mature erythrocytes.