The Formation of Haemoglobin during the
Development of the Erythrocytes
by
THORELL 1
BO
From the Department of Pathology, Karolinska Institutet, Stockholm
the functional point of view the processes of differentiation during the
formation of the red blood-cells are characterized by the synthesis of haemoglobin.
If the haemoglobin content of single erythroblasts is measured one finds that
most of the formation of haemoglobin occurs in the later stages of erythropoiesis
(Table 1).
FROM
TABLE 1
Cell diameter, p
Growing
(
erythroblasts [
110
10-5
9-5
8-5
80
7-5
70
6-5
Mature cell
Total amount o/Hb
(io- 12 g.)
0
0
0-5
2
4
10
22
25
28
When it reaches these stages of development the growth and division processes of the erythroblasts have been completed. The cytoplasm has lost its
basophilia and the nuclei are becoming pycnotic. The cells are, however, capable
of forming haemoglobin.
From the general point of view of cell physiology, it seems reasonable to
believe that only the prosthetic group (haem) is being synthesized during these
later stages of erythropoiesis. The globin-protein might be manufactured mainly
in earlier, growing erythroblasts in the presence of ribosepolynucleotides which
are abundant in the cytoplasm of these cells.
To test this view, a series of experiments was made in collaboration with Dr.
Hammarsten, using hens which were regenerating red cells intensely after a
1
Author's address: Department of Pathology, Karolinska Institutet, Stockholm.
[J. Embryo!, exp. Morph. Vol. 1, Part 3, pp. 235-237, September 1953]
236
B. THORELL—HAEMOGLOBIN FORMATION DURING
single, severe haemolysis produced by an injection of phenylhydrazine. Thirtysix hours after the haemolysis the content of immature erythroblasts in the peripheral blood exhibited a sharp rise. The peak value was reached around 60
hours, after which time the cells in the blood were undergoing their final maturation (Fig. 1).
25
•/.IMMATURE
20 BLOOD CELLS
15
10
•5
36UJ48
72|BJ 84 HOURS
lei
FIG. 1. Curves representing the proportion of
immature cells, containing less than 510~ 1 2 g.
of haemoglobin, in the peripheral blood of
the experimental animals. The short curve on
the left is for hen A; the lower curve for hen B;
and the upper curve (points marked with open
circles) for hen C. On the abscissa is plotted
the time after phenylhydrazine haemolysis.
The arrows indicate the first and last injection
of labelled glycine in each hen.
At different stages of this blood-cell regeneration the hens were given glycine
labelled with N15 intraperitoneally. Glycine was chosen because it is directly
incorporated into the haemin and the proteins (Shemin & Rittenberg, 1946;
Eliasson et al., 1951). After a certain lapse of time the hens were sacrificed by
exsanguination, and the different substances in the blood-cells were separated,
degraded, and analysed.
Thus we aimed at investigating whether or not the ratio of N15 incorporation
into the globin and into the haemin was the same in erythroblasts at different
stages of maturation.
Fig. 1 shows the principle of such an experiment. The first hen (A) was given
isotope during a period when the amount of immature cells in the peripheral
blood was increasing. Six hours later the animal was sacrificed and the isotope
concentration in the haemin and the globin analysed. The second hen (B) was
given labelled glycine when the immature blood-cells were decreasing in amount,
i.e. during their final maturation. It also was killed 6 hours later. The third hen
ERYTHROCYTE DEVELOPMENT
237
(C) received isotope during a period when its immature blood-cells were increasing, but it was not sacrificed until 38 hours later when the blood-cells were in the
process of final maturation.
It will be seen in Table 2 that in the first hen globin synthesis predominates in
relation to haemin synthesis. In the second hen the condition is reversed; haemin
production predominates in the blood-cells undergoing their final maturation.
The third hen shows a markedly dominant incorporation in the globin, indicating an intense globin synthesis in the cells during the period around the isotope injection. The level of N15-concentration in glycine at the time of the haemin
synthesis has been low.
TABLE 2
Atom % excess N16 in glyc,
:ine
isolated from globin
Atom % excess N15
in haemin
Ratio haemin Iglycine
1-627
0-956
5-29
1-177
1-558
0-465
0-72
1-63
009
A
B
C
Thus the ratio of the incorporation values for globin to those for haemin
isolated from erythroblasts at different stages of maturation indicates that during
erythropoiesis the maximum rate of the synthesis of globin precedes that of
haemin.
In general terms it seems reasonable to suggest that the endocellular synthetic
processes which form the basis of the functional differentiation of the erythroblasts are separated and distributed over a relatively wide range of the development. During a certain phase of this development the cell has a given pattern of
enzymatic activities and a given part of its functional differentiation is elaborated.
REFERENCES
THORELL, B. (1947). Studies on the Formation of Cellular Substances during Blood Cell Production. London: Henry Kimpton.
(1950a). Faraday Soc. Disc. 9,432.
(19506). Rev. Hemat. 5, 561.
SHEMIN, D., & RITTENBERG, D. (1946). / . biol. Chem. 166, 621.
ELIASSON, N. A., HAMMARSTEN, E., REICHARD, P., AQVIST, S., THORELL, B., & EHRENSVARD, G.
(1951). Ada chem. scand. 5, 431.
HAMMARSTEN, E., THORELL, B., AQVIST, S., ELIASSON, N., & AKERMAN, L. (1953). Exp. Cell. Res.
(in the press).