We cultured human umbilical cord blood erythropoietic precursors in methyl cellulose clonal assay and analyzed the synthetic rates of Hb A and Hb F in individual erythropoietic bursts. Hemoglobin was labeled with 14C-amino acids in culture, separated by slab gel isoelectric focusing techniques, and quantitated by fluorographic methods. Almost all bursts exhibited both Hb A and Hb F in varying ratios. Frequencies of the individual bursts differing in percentage Hb F biosynthesis had normal distributions. Natal erythropoietic precursors appeared to be randomly committed to Hb F synthesis.

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Copyright © 1979 by The American Society of Hematology
1979
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