VITELLINE MEMBRANE AND CORTICAL PARTICLES 287
The results obtained after treatment with periodate and albumin
demonstrate the compartmentation in the surface of the egg. As already
pointed out, the natural inhibitor present inside the plasma membrane
may be identical with or at least similar to the inhibitor outside this
membrane. The inhibitor outside the membrane may even result from
a secretion of the inhibitor present inside the plasma membrane. This
secretion may occur during the maturation divisions and continue for
some time after these. According to the model of Sasaki and Nogucki
(1959) even a slight change in the configuration of the molecule of the
inhibitor may be critical, as follows also from another model represented
by the jelly coat substance in solution, which in sufficient concentration
acts as a fertilization inhibitor. This model is closer to the conditions in
the egg than the previously discussed one. Vasseur and Wicklund (1953)
heated the jelly coat solution to 90-100°C for 1-2 hr and found that its
property as fertilization inhibitor became much weaker. This property
may be bound to a rather specific configuration of the inhibitor. The
jelly coat substance in solution increases the mobility of the spermatozoa;
heating enhances this effect of the jelly coat substance.
G. The Impact of the Cortical Changes on Protein
Synthesis and Centrosome Replication
Protein synthesis is not active in the mature unfertilized egg. Protein
synthesis was demonstrated after fertilization by a study of the incorporation of labeled amino acids into Paracentrotus
eggs. The rate of
incorporation rose rapidly (see T. Hultin, 1950c, 1961 ; Hultin and Bergstrand, 1960; Nakano and Monroy, 1958; Monroy, 1960). Hultin (1961)
showed that the change occurs at the level of the ribosomes. Ribosomes
removed from the unfertilized eggs proved to be inactive in incorporation experiments, even after addition of supplementary factors, such as
soluble ribonucleic acid (RNA) and adenosine triphosphate. Conversely,
ribosomes removed from the fertilized egg showed, even as early as 10
min after insemination, a pronounced incorporation under the same
conditions. In the experiments with ribosomes the incorporation increased
with increasing time after insemination (Hultin, 1961, Fig. 3). The
prerequisite was the formation of polysomes, i.e., ribosomes kept together
in array by strands of messenger RNA (Monroy and Tyler, 1963).
Hultin (1961) subjected the eggs to short treatment with butyric acid
following the method described by Loeb (1913). After this treatment the
eggs undergo cortical changes that often are indistinguishable from the
events in fertilized eggs. Moreover, the incorporation of labeled amino
acids is induced, and the rate increases even more rapidly than in normal
fertilized eggs. T. Hultin (1964) considers that the increase in protein
The results obtained after treatment with periodate and albumin
demonstrate the compartmentation in the surface of the egg. As already
pointed out, the natural inhibitor present inside the plasma membrane
may be identical with or at least similar to the inhibitor outside this
membrane. The inhibitor outside the membrane may even result from
a secretion of the inhibitor present inside the plasma membrane. This
secretion may occur during the maturation divisions and continue for
some time after these. According to the model of Sasaki and Nogucki
(1959) even a slight change in the configuration of the molecule of the
inhibitor may be critical, as follows also from another model represented
by the jelly coat substance in solution, which in sufficient concentration
acts as a fertilization inhibitor. This model is closer to the conditions in
the egg than the previously discussed one. Vasseur and Wicklund (1953)
heated the jelly coat solution to 90-100°C for 1-2 hr and found that its
property as fertilization inhibitor became much weaker. This property
may be bound to a rather specific configuration of the inhibitor. The
jelly coat substance in solution increases the mobility of the spermatozoa;
heating enhances this effect of the jelly coat substance.
G. The Impact of the Cortical Changes on Protein
Synthesis and Centrosome Replication
Protein synthesis is not active in the mature unfertilized egg. Protein
synthesis was demonstrated after fertilization by a study of the incorporation of labeled amino acids into Paracentrotus
eggs. The rate of
incorporation rose rapidly (see T. Hultin, 1950c, 1961 ; Hultin and Bergstrand, 1960; Nakano and Monroy, 1958; Monroy, 1960). Hultin (1961)
showed that the change occurs at the level of the ribosomes. Ribosomes
removed from the unfertilized eggs proved to be inactive in incorporation experiments, even after addition of supplementary factors, such as
soluble ribonucleic acid (RNA) and adenosine triphosphate. Conversely,
ribosomes removed from the fertilized egg showed, even as early as 10
min after insemination, a pronounced incorporation under the same
conditions. In the experiments with ribosomes the incorporation increased
with increasing time after insemination (Hultin, 1961, Fig. 3). The
prerequisite was the formation of polysomes, i.e., ribosomes kept together
in array by strands of messenger RNA (Monroy and Tyler, 1963).
Hultin (1961) subjected the eggs to short treatment with butyric acid
following the method described by Loeb (1913). After this treatment the
eggs undergo cortical changes that often are indistinguishable from the
events in fertilized eggs. Moreover, the incorporation of labeled amino
acids is induced, and the rate increases even more rapidly than in normal
fertilized eggs. T. Hultin (1964) considers that the increase in protein