PROTEINS IN DEVELOPMENT
225
bufo serum after it has been precipitated with a,nti-Bufo viridis serum
and vice versa. But only molecules BV are present at the tail bud stage,
i.e. it is impossible to obtain any precipitation of the fraction with antiB. viridis serum if it has been precipitated previously with &nti-Bufo
bufo serum and vice versa (Fig. 13).
When studying the reciprocal crosses of the two toad species Bufo bufo
and Bufo viridis, it is possible to demonstrate that the first precipitation
which occurs during cleavage may be produced by the antiserum prepared against the maternal and paternal species respectively. This
means that substances are synthesized during cleavage under the influence of the paternal and maternal genes. It is also possible to study the
problems of molecular ontogenesis from a genetical point of view in the
hybrids (Ranzi, 1960b). After the early blastula stage only antigens BV
can be detected in the fraction precipitating at a concentration of
ammonium sulphate between 50 and 70% of saturation, in the viable
cross B. bufo ? χ ΰ . viridis £. BV antigens are absent in the non-viable
cross B. viridis $ x B. bufo
Samuelli, 1961). We may therefore conclude that the non-viable cross
is unable to combine the two reactive groups in the same molecule,
while this possibility exists in the reciprocal viable cross. This inability
to combine the two reactive groups in one BV molecule can be related
to the well-known low synthetic activity in the non-viable crosses of
amphibians (Gregg, 1957).
C. Attempt at Comparison
Some interesting facts appear from the above data. The peculiar
salting-out diagrams of the sea urchin differ from those of the three
species of anura studied. The morphological differences in development
between sea urchins and anura correspond to differences in protein
differentiation.
Moreover, a similar process is detectable in all the animals studied.
Fertilization is related to a decrease in protein solubility according
to the early work of Mirsky (1936) and now we know that in three
species of sea urchin (Arbacia lixula, A. punctulata and Strongylocentrotus
purpuratus), three species of anura (Rana esculenta, Bufo bufo and B.
viridis), and, according to Cigada Leonardi (1956) in the silk worm
(Bombyx mori) also, the solubility of proteins decreases with fertilization, so that in all species studied the fertilization reaction is the same,
independently of the cleavage pattern.
Comparison of the protein synthesis between different animals was
studied by another worker (Cigada, M., 1953; Cigada Leonardi, 1956,
1958). She fractionated structural protein II, structural protein I and
225
bufo serum after it has been precipitated with a,nti-Bufo viridis serum
and vice versa. But only molecules BV are present at the tail bud stage,
i.e. it is impossible to obtain any precipitation of the fraction with antiB. viridis serum if it has been precipitated previously with &nti-Bufo
bufo serum and vice versa (Fig. 13).
When studying the reciprocal crosses of the two toad species Bufo bufo
and Bufo viridis, it is possible to demonstrate that the first precipitation
which occurs during cleavage may be produced by the antiserum prepared against the maternal and paternal species respectively. This
means that substances are synthesized during cleavage under the influence of the paternal and maternal genes. It is also possible to study the
problems of molecular ontogenesis from a genetical point of view in the
hybrids (Ranzi, 1960b). After the early blastula stage only antigens BV
can be detected in the fraction precipitating at a concentration of
ammonium sulphate between 50 and 70% of saturation, in the viable
cross B. bufo ? χ ΰ . viridis £. BV antigens are absent in the non-viable
cross B. viridis $ x B. bufo
Samuelli, 1961). We may therefore conclude that the non-viable cross
is unable to combine the two reactive groups in the same molecule,
while this possibility exists in the reciprocal viable cross. This inability
to combine the two reactive groups in one BV molecule can be related
to the well-known low synthetic activity in the non-viable crosses of
amphibians (Gregg, 1957).
C. Attempt at Comparison
Some interesting facts appear from the above data. The peculiar
salting-out diagrams of the sea urchin differ from those of the three
species of anura studied. The morphological differences in development
between sea urchins and anura correspond to differences in protein
differentiation.
Moreover, a similar process is detectable in all the animals studied.
Fertilization is related to a decrease in protein solubility according
to the early work of Mirsky (1936) and now we know that in three
species of sea urchin (Arbacia lixula, A. punctulata and Strongylocentrotus
purpuratus), three species of anura (Rana esculenta, Bufo bufo and B.
viridis), and, according to Cigada Leonardi (1956) in the silk worm
(Bombyx mori) also, the solubility of proteins decreases with fertilization, so that in all species studied the fertilization reaction is the same,
independently of the cleavage pattern.
Comparison of the protein synthesis between different animals was
studied by another worker (Cigada, M., 1953; Cigada Leonardi, 1956,
1958). She fractionated structural protein II, structural protein I and