The accumulation of basic nonhemoglobin proteins during the differentiation of primitive (embryonic) red cells of amphibia

Abstract

The preferential accumulation of hemoglobin is a characteristic of the differentiation of definitive (adult) red blood cells. Since primitive (embryonic or larval) red blood cells have many properties which contrast with definitive red cells, the accumulation of red cell proteins was analyzed during the differentiation of primtive red cells to determine whether or not hemoglobin was the only protein which showed a substantial increase in amount. Primitive red cells of amphibia were used because the mature circulating cell retains large amounts (13%) of specific, well characterized, nonhemoglobin proteins (CP). Preparations of primitive red cells enriched in immature cells were obtained from the circulation of bullfrog tadpoles recovering from phenylhydrazine-induced anemia. The amount of CP, determined by electrophoresis, imunodiffusion, and ion-exchange chromatography, was compared for red cells from normal animals and anemic animals. Mature cells contained three to six times the amount of CP and three times the amount of hemoglobin found in the population of red cells enriched in immature cells. The accumulation of CP during maturation of primitive red cells indicates that differentiation of primitive red cells is less restrictive than differentiation of definitive red cells. Since the primitive red cell is less specialized than the definitive red cell, it is possible that primitive red cells have several roles in the developing animal, in contrast to the single role of synthesizing and maintaining hemoglobin in the adult animal.