106
ALBERTO MONROY AND RACHELE MAGGIO
I500I
1
1
1
1
1
z
lOOOh
E
1
ι
ι
ι
I
1
0
2
4
6
10
18
Hours after fertilization
FIG. 5. In the unfertilized eggs (points on the ordinate) obtained from females injected
with
85
S-methionine, the radioactivity in the low molecular pool is high. (Comparison
with Figs. 3 and 4 indicates that in these eggs the radioactivity in the mitochondria,
microsomes and soluble proteins is negligible.) A rapid drop of the radioactivity occurs
after fertilization and in the course of development. (From Nakano and Monroy, 1958a.)
to the 32- to 64-cell stage, undergoes a decline and then starts rising
again at the mesenchyme blastula reaching a second peak at the midgastrula. Their incorporation in the whole TCA-insoluble fraction and in
the proteins of the mitochondria, microsomes and cell fluid follows a
similar curve (Giudice et al., 1962) (Fig. 6 a and b). Also when
14
C-glucose
is administered to the eggs and embryos (Monroy and Vittorelli, 1962)
the rate of incorporation in the total proteins undergoes a rapid increase
beginning immediately after fertilization, reaching a maximum at the
32- to 64-cell stage, and then decreasing. At the mesenchyme blastula
stage it rises again until the mid-gastrula and then drops somewhat
(Fig. 7). A progressive increase of incorporation into the carboxyl group
of proteins beginning immediately after fertilization has also been
observed by Hultin and Wessel (1952) following an exposure of the eggs
to
14
C-carbon dioxide for 3| hours. In their experiments, however, the
first peak of incorporation was reached at the time of hatching. This
was followed by a plateau and then the curve started rising again at the
mesenchyme blastula. Thus, the curve obtained by these investigators
followed the respiratory curve more closely. In the experiments in
ALBERTO MONROY AND RACHELE MAGGIO
I500I
1
1
1
1
1
z
lOOOh
E
1
ι
ι
ι
I
1
0
2
4
6
10
18
Hours after fertilization
FIG. 5. In the unfertilized eggs (points on the ordinate) obtained from females injected
with
85
S-methionine, the radioactivity in the low molecular pool is high. (Comparison
with Figs. 3 and 4 indicates that in these eggs the radioactivity in the mitochondria,
microsomes and soluble proteins is negligible.) A rapid drop of the radioactivity occurs
after fertilization and in the course of development. (From Nakano and Monroy, 1958a.)
to the 32- to 64-cell stage, undergoes a decline and then starts rising
again at the mesenchyme blastula reaching a second peak at the midgastrula. Their incorporation in the whole TCA-insoluble fraction and in
the proteins of the mitochondria, microsomes and cell fluid follows a
similar curve (Giudice et al., 1962) (Fig. 6 a and b). Also when
14
C-glucose
is administered to the eggs and embryos (Monroy and Vittorelli, 1962)
the rate of incorporation in the total proteins undergoes a rapid increase
beginning immediately after fertilization, reaching a maximum at the
32- to 64-cell stage, and then decreasing. At the mesenchyme blastula
stage it rises again until the mid-gastrula and then drops somewhat
(Fig. 7). A progressive increase of incorporation into the carboxyl group
of proteins beginning immediately after fertilization has also been
observed by Hultin and Wessel (1952) following an exposure of the eggs
to
14
C-carbon dioxide for 3| hours. In their experiments, however, the
first peak of incorporation was reached at the time of hatching. This
was followed by a plateau and then the curve started rising again at the
mesenchyme blastula. Thus, the curve obtained by these investigators
followed the respiratory curve more closely. In the experiments in