ANIMALIZATION AND VEGETALIZATION
167
is observed that these agents inhibit development and do not favour the
extension of the ectoderm (Lallier, 1956a and unpublished observations).
Salyrgan, an organic mercurial, inhibits the hexosemonophosphate
shunt at the level of phosphoriboisomerase (Bruns et ah, 1958). Salyrgan
is an effective animalizing agent (Lallier, 1960a). In the presence of these
difficulties it appears necessary to study and to compare the activity of
the hexosemonophosphate shunt in embryos treated by various animalizing agents.
VI. Metabolism of Amino-acids and Proteins
The first suggestion of the participation of protein metabolism in the
processes of determination came from Lindahl (1936). It concerns the
interpretation of the animalization obtained by culturing blastulae in
the absence of sulphate ions, a phenomenon discovered by Herbst
(1897). In the absence of sulphate ions, the vegetative parts of the egg
are inhibited while the animal parts are not affected. The animalization
obtained in this way is slightly different from the one caused by thiocyanate. According to Lindahl, sulphate ions are likely to be used to
detoxicate and remove the aromatic waste-products of protein catabolism. The predominance of the catabolism of proteins in the vegetal
parts of the eggs would explain their peculiar susceptibility to a lack of
sulphate ions. To test this hypothesis, Lindahl and Stordahl (1937) have
studied the effects of various sulphuric esters of phenol and indole on the
development of eggs. Only indoxylsulphate was able to provoke
animalization, in fact an atypical one.
A more direct approach is the study of the distribution of the proteolytic enzymes. The research done on peptidase has shown that at the
8-blastomere stage the animal and vegetal blastomeres have the same
peptidase content. The distribution of the enzyme seems uniform until
the pluteus stage (Holter and Linderstrom-Lang, 1938a, b; Holter and
Lindahl, 1941).
Owing to improvements in the biochemical techniques, it has been
possible to make considerable progress in the study of amino-acid and
protein metabolism. Gustafson and Hjelte (1951) have studied the
amino-acid composition of the sea urchin egg during development. In
early development the changes in the composition of amino-acids are
relatively small. The accumulation of glutamine and of peptides has
been observed during that period. From the mesenchyme blastula stage
and during gastrulation, the changes in content of amino-acids become
more important and a more intensive protein synthesis takes place.
Lithium treatment slows the rise in glutamine turnover rate and the
synthesis of peptides and proteins. Kavanau (1954) has investigated the
167
is observed that these agents inhibit development and do not favour the
extension of the ectoderm (Lallier, 1956a and unpublished observations).
Salyrgan, an organic mercurial, inhibits the hexosemonophosphate
shunt at the level of phosphoriboisomerase (Bruns et ah, 1958). Salyrgan
is an effective animalizing agent (Lallier, 1960a). In the presence of these
difficulties it appears necessary to study and to compare the activity of
the hexosemonophosphate shunt in embryos treated by various animalizing agents.
VI. Metabolism of Amino-acids and Proteins
The first suggestion of the participation of protein metabolism in the
processes of determination came from Lindahl (1936). It concerns the
interpretation of the animalization obtained by culturing blastulae in
the absence of sulphate ions, a phenomenon discovered by Herbst
(1897). In the absence of sulphate ions, the vegetative parts of the egg
are inhibited while the animal parts are not affected. The animalization
obtained in this way is slightly different from the one caused by thiocyanate. According to Lindahl, sulphate ions are likely to be used to
detoxicate and remove the aromatic waste-products of protein catabolism. The predominance of the catabolism of proteins in the vegetal
parts of the eggs would explain their peculiar susceptibility to a lack of
sulphate ions. To test this hypothesis, Lindahl and Stordahl (1937) have
studied the effects of various sulphuric esters of phenol and indole on the
development of eggs. Only indoxylsulphate was able to provoke
animalization, in fact an atypical one.
A more direct approach is the study of the distribution of the proteolytic enzymes. The research done on peptidase has shown that at the
8-blastomere stage the animal and vegetal blastomeres have the same
peptidase content. The distribution of the enzyme seems uniform until
the pluteus stage (Holter and Linderstrom-Lang, 1938a, b; Holter and
Lindahl, 1941).
Owing to improvements in the biochemical techniques, it has been
possible to make considerable progress in the study of amino-acid and
protein metabolism. Gustafson and Hjelte (1951) have studied the
amino-acid composition of the sea urchin egg during development. In
early development the changes in the composition of amino-acids are
relatively small. The accumulation of glutamine and of peptides has
been observed during that period. From the mesenchyme blastula stage
and during gastrulation, the changes in content of amino-acids become
more important and a more intensive protein synthesis takes place.
Lithium treatment slows the rise in glutamine turnover rate and the
synthesis of peptides and proteins. Kavanau (1954) has investigated the