248
SILVIO RANZI
The curves show that in the protein solutions of embryos treated with
NaSCN or IBA a greater quantity of material remains in solution than
is found in the controls; in the solutions of embryos treated with LiCl
less material remains in solution.
The proteins of the non-viable toad cross Bufo viridis $ x Bufo bufo$
are digested to a lesser extent than the proteins of the parental species
and of the viable hybrid Bufo bufo $ x Bufo viridis £. The digestion
pattern of the non-viable hybrid is identical to that of Li-treated Bufo
bufo embryos (Fig. 38).
We may conclude that the proteins of animalized embryos are also
less resistant to urea and proteolytic enzymes than the proteins of the
control embryos. The proteins of vegetalized embryos (or the proteins
of the non-viable toad cross) are on the contrary more resistant to urea
and proteolytic enzymes.
These data on the digestion by proteolytic enzymes seem to be important because proteolytic digestion is one of the physiological processes
occurring in developing embryos.
G. Predisposition to and Inhibition of
Protoplasmic Structural Breakdown
The action of animalizing agents which predisposes to breakdown and
of vegetalizing agents which inhibits breakdown, has been shown also
in some cellular organelles. Orlandi (1953) showed that Nal, NaSCN,
urea, IBA and high pH bring about disintegration of isolated chromosomes, while LiCl has a protective effect. L. Cigada (1954) showed that
Nal, NaSCN, methylene blue and high pH cause disintegration of isolated
yolk granules while LiCl and thiourea have a protective effect. Brioschi
(1955) working on glycerinated muscle fibres showed that while in the
presence of vegetalizing substances they regularly contract under the
influence of ATP, this property is lost or reduced after treatment with
animalizing agents. Gallera and Baud (1954) showed that ectoderm cells
of Pleurodeles neurulae, after treatment with urea, lose their ultrastructures and look like cells of younger stages; their competence is
increased by this treatment.
The inducing effect of animalizing agents and the inhibitory effect of
vegetalizing agents on breakdown are therefore phenomena which concern not only embryonic proteins, but also structures in the cell.
The same plan of investigation was applied to living embryos (Ranzi,
1959). Embryos of Arbacia punctulata were animalized with NaSCN or
IBA, or vegetalized with LiCl, and after a suitable period were washed
carefully to free them from the active agents. In the first series of experiments 2-5 ml of a 60% solution of urea were added to 7-5 ml of the culture suspension. (Instead of urea, a 0 2 % trypsin solution may be added
SILVIO RANZI
The curves show that in the protein solutions of embryos treated with
NaSCN or IBA a greater quantity of material remains in solution than
is found in the controls; in the solutions of embryos treated with LiCl
less material remains in solution.
The proteins of the non-viable toad cross Bufo viridis $ x Bufo bufo$
are digested to a lesser extent than the proteins of the parental species
and of the viable hybrid Bufo bufo $ x Bufo viridis £. The digestion
pattern of the non-viable hybrid is identical to that of Li-treated Bufo
bufo embryos (Fig. 38).
We may conclude that the proteins of animalized embryos are also
less resistant to urea and proteolytic enzymes than the proteins of the
control embryos. The proteins of vegetalized embryos (or the proteins
of the non-viable toad cross) are on the contrary more resistant to urea
and proteolytic enzymes.
These data on the digestion by proteolytic enzymes seem to be important because proteolytic digestion is one of the physiological processes
occurring in developing embryos.
G. Predisposition to and Inhibition of
Protoplasmic Structural Breakdown
The action of animalizing agents which predisposes to breakdown and
of vegetalizing agents which inhibits breakdown, has been shown also
in some cellular organelles. Orlandi (1953) showed that Nal, NaSCN,
urea, IBA and high pH bring about disintegration of isolated chromosomes, while LiCl has a protective effect. L. Cigada (1954) showed that
Nal, NaSCN, methylene blue and high pH cause disintegration of isolated
yolk granules while LiCl and thiourea have a protective effect. Brioschi
(1955) working on glycerinated muscle fibres showed that while in the
presence of vegetalizing substances they regularly contract under the
influence of ATP, this property is lost or reduced after treatment with
animalizing agents. Gallera and Baud (1954) showed that ectoderm cells
of Pleurodeles neurulae, after treatment with urea, lose their ultrastructures and look like cells of younger stages; their competence is
increased by this treatment.
The inducing effect of animalizing agents and the inhibitory effect of
vegetalizing agents on breakdown are therefore phenomena which concern not only embryonic proteins, but also structures in the cell.
The same plan of investigation was applied to living embryos (Ranzi,
1959). Embryos of Arbacia punctulata were animalized with NaSCN or
IBA, or vegetalized with LiCl, and after a suitable period were washed
carefully to free them from the active agents. In the first series of experiments 2-5 ml of a 60% solution of urea were added to 7-5 ml of the culture suspension. (Instead of urea, a 0 2 % trypsin solution may be added