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The Control of Embryonic Hemoglobin Synthesis - …

In humans, different types of hemoglobin molecules are synthesized during the embryonic, fetal and adult stages.

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Regulation of chicken embryo hemoglobin synthesis

Primitive erythroblasts in the circulating blood of the chick embryo continue to divide while synthesizing hemoglobin (Hb). Hb measurements on successive generations of erythroblasts show that there is a progressive increase in the Hb content of both interphase and metaphase cells. Furthermore, for any given embryo the Hb content of metaphase cells is always significantly greater than that of interphase cells. The distribution of Hb values for metaphase cells suggests that there are six Hb classes corresponding to the number of cell cycles in the proliferative phase. The location of erythroblasts in the cell cycle was determined by combining Feulgen cytophotometry with thymidine radioautography on the same cells. Measurements of the Hb content for erythroblasts in different compartments of the cell cycle (G1, S, G2, and M) show a progressive increase through the cycle. Thus, the amount of Hb per cell is a function of the number of cell divisions since the initiation of Hb synthesis and, to a lesser degree, the stage of the cell cycle. Earlier generations of erythroblasts synthesize Hb at a faster rate than the terminal generation. Several models have been proposed to explain these findings.

and hemoglobin Portland (y252), are synthesized and remain in the embryo for the 3 months

Hemoglobin Hemoglobin synthesis results from an orderly evolution of a series of embryonic, fetal and adult hemoglobins.

Hemoglobin Synthesis - Harvard University

DEVELOPMENTAL BIOLOGY 49, 556-562 (1976) Hemoglobin Synthesis in Isolated Erythroid Colonies from the Chick Embryo1 KAY S. …

The rate of synthesis of different hemoglobin (Hb) species — embryonic, primitive, definitive, and adult — in the circulating red cells of the chick embryo have been measured. On the fifth day of chick embryogenesis, there is a marked decrease in the capability of these red cells to synthesize Hb. The rates of synthesis of embryonic and primitive Hb decrease markedly compared to that of definitive and adult Hb. On the fourth day of embryogenesis nucleic acid synthesis drops sharply in these cells. These decreases in metabolic activity preceed the disappearance of the primitive erythrocyte from the chick embryo circulation. It appears that the primitive cell line is specifically shut off with respect to its metabolic activities and possibly destroyed at this time.

N2 - The rate of synthesis of different hemoglobin (Hb) species — embryonic, primitive, definitive, and adult — in the circulating red cells of the chick embryo have been measured. On the fifth day of chick embryogenesis, there is a marked decrease in the capability of these red cells to synthesize Hb. The rates of synthesis of embryonic and primitive Hb decrease markedly compared to that of definitive and adult Hb. On the fourth day of embryogenesis nucleic acid synthesis drops sharply in these cells. These decreases in metabolic activity preceed the disappearance of the primitive erythrocyte from the chick embryo circulation. It appears that the primitive cell line is specifically shut off with respect to its metabolic activities and possibly destroyed at this time.

Hemoglobin a Synthesis in the Developing Fetus — NEJM

| The chick embryo begins rapid synthesis of hemoglobin in the blood islands of the extraembryonic mesoderm at the …

AB - The rate of synthesis of different hemoglobin (Hb) species — embryonic, primitive, definitive, and adult — in the circulating red cells of the chick embryo have been measured. On the fifth day of chick embryogenesis, there is a marked decrease in the capability of these red cells to synthesize Hb. The rates of synthesis of embryonic and primitive Hb decrease markedly compared to that of definitive and adult Hb. On the fourth day of embryogenesis nucleic acid synthesis drops sharply in these cells. These decreases in metabolic activity preceed the disappearance of the primitive erythrocyte from the chick embryo circulation. It appears that the primitive cell line is specifically shut off with respect to its metabolic activities and possibly destroyed at this time.

Figure 6 The genes encoding the a and non-a chains that come together to form the hemoglobin tetramer lie on chromosomes 16 and 11, respectively. The a genes are present at duplicated loci. Six distinct species of normal hemoglobin have been described. Three of these hemoglobins are synthesized only during embryonic stages of development (Hb Gower 1, Hb Portland, and Hb Gower 2). HbF predominates during fetal development, and a small amount continues to be synthesized in adult life. HbA and HbA2 constitute the major forms of adult hemoglobin. Different hemoglobin genes are activated at various stages of development. In the embryo, | chains combine with e chains to yield Hb Gower 1 and with y chains to form Hb Portland; a and e chains are linked to form Hb Gower 2. There are two varieties of y chains that are derived from separate loci and that differ in a single amino acid; y contains glycine at position 136, whereas Ay contains alanine at this position. The genes coding for the two other non-a chains, | and 8, which are required for the synthesis of adult hemoglobins, are switched on late in fetal development. The factors regulating this precisely coordinated sequence of changes in hemoglobin production are poorly understood; some evidence suggests that DNA segments intervening between the various hemoglobin genes may control the relative rates of synthesis of the adjacent gene products.

24/12/2016 · 1. Blood Cells. 1981;7(1):165-76. Embryonic and fetal hemoglobin synthesis in K562 cell line. Guerrasio A, Vainchenker W, …
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  • Function and Synthesis of Hemoglobin - Interactive …

    Hemoglobin synthesis results from an orderly evolution of a series of embryonic, fetal and adult hemoglobins

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