The synthesis of adult hemoglobins during hepatic erythropoiesis in the calf fetus.

We investigated hemoglobin synthesis in suspension cultures of liver erythroid cells obtained from calf fetuses of 103 to 198 days. A significant amount of radioactivity was associated with adult hemoglobins which were separated from the fetal hemoglobins by isoelectric focusing, even after purification of the cell hemolysates by chromatography on Sephadex G-100. A radioactive beta-globin fraction was isolated by chromatography on carboxymethyl-cellulose from hemolysates, which were first fractionated on Sephadex G-100. Fingerprint analysis of peptides obtained by trypsinolysis of radioactive beta-globin chains revealed that its structure was closely related to that of beta-globin, isolated from cow bone marrow cells. The amount of beta-globin which was synthesized by calf liver cells varied from 0.3 to 3.5% of the non-alpha globin chains and remained at a low level for all the fetuses which were studied. Our results indicate that the bovine fetal liver is a valuable model to investigate the switch from fetal to adult hemoglobin synthesis.