Erythropoiesis in the duck embryo: accumulation of H5 histone during red blood cell maturation.

We have studied the variation in histone composition of the red blood cell during embryonic development of the duck. The problem has been approached by fractionating the cells according to maturity and type in bovine serum albumin density gradients and analyzing electrophoretically histones which have been extracted from purified cell populations. Additional data have been obtained by pulse-labeling experiments and by immunofluorescence techniques. The results indicate that histone H5 may be absent from very immature primitive embryonic red blood cells and that it accumulates in the nucleus during maturation of the cell. A similar relative increase in H5 content is observed during maturation of the definitive erythroid series. Mature adult erythrocytes and mature erythrocytes of the definitive series contain comparable amounts of histone H5 which is present in lower amounts in the mature cells of the primitive cell line.