162
R. LALLIER
In the first, the carbohydrates are metabolized according to the EmbdenMeyerhoff pathway and the tricarboxylic acid cycle (Cleland and
Rothschild, 1952a, b; Yëas, 1954). In the second, the carbohydrates are
oxidized by the pathway of the hexosemonophosphate shunt (Krahl
etal, 1955; Krahl, 1956).
Lindahl (1936) has shown that lithium inhibits some reactions of
glycolysis, namely the reduction of methylene blue by sea urchin egg
homogenates in the presence of hexosemonophosphate. The activity of
triosephosphate dehydrogenase is inhibited by lithium ; but lithium has
no effect on the activity of other enzymes of glycolysis such as hexokinase
and aldolase (Lallier, 1954).
Research has been undertaken to discover whether the inhibitors of
glycolysis exert vegetalizing effects comparable to those of lithium.
The halogen derivatives of acetic acid such as the monoiodacetic acid,
its amide and bromoacetic acid, inhibit glycolysis at the level of
triosephosphate dehydrogenase. Iodoacetate is very weakly vegetalizing
(Runnström, 1935b). The monoiodacetamide exerts a very strong
cytolytic action on the eggs (Lindahl, 1939). Bromoacetic acid provokes
an increase of primary mesenchyme (Tchakhotine, 1938). This phenomenon may correspond to a weak and atypical vegetalization. DLGlyceraldehyde inhibits glycolysis by interfering with the reaction of
the hexokinase (Lardy et al., 1950). DL-Glyceraldehyde does not provoke
the vegetalization of the sea urchin egg (Needham and Needham, 1940).
Phlorizin inhibits the phosphorylation of glycogen into glucose-1phosphate. It does not have vegetalizing effects (Needham and Needham,
1940). However, these authors point out that the weak solubility of
phlorizin in sea-water must strongly diminish its activity on the sea
urchin egg.
2-Deoxyglucose, an analogue of glucose, inhibits glycolysis. The
blocking appears to take place at the level of phosphohexoisomerase, an
enzyme that catalyses the transformation of glucose-6-phosphate into
fructose-6-phosphate (Sols and Crane, 1954). 2-Deoxyglucose does not
exert vegetalizing effects, and moreover, it does not prevent the
vegetalizing action of lithium (Lallier, 1960b, c).
The inhibition of cytochrome oxidase, the terminal enzyme of the
tricarboxylic acid cycle, by cyanide or carbon monoxide does not exert
vegetalizing effects comparable to those of lithium (Runnström, 1928c;
Hörstadius and Strömberg, 1940). However, Child (1948) and Rulon
(1950) with sodium azide have obtained exogastrulation and definite
vegetalization of larvae. Sodium malonate and selenite inhibit succinic
dehydrogenase, an important enzyme of the tricarboxylic cycle. In
sand-dollar eggs sodium malonate is not vegetalizing and selenite exerts
some radializing effects (Rulon, 1951,1952a).
R. LALLIER
In the first, the carbohydrates are metabolized according to the EmbdenMeyerhoff pathway and the tricarboxylic acid cycle (Cleland and
Rothschild, 1952a, b; Yëas, 1954). In the second, the carbohydrates are
oxidized by the pathway of the hexosemonophosphate shunt (Krahl
etal, 1955; Krahl, 1956).
Lindahl (1936) has shown that lithium inhibits some reactions of
glycolysis, namely the reduction of methylene blue by sea urchin egg
homogenates in the presence of hexosemonophosphate. The activity of
triosephosphate dehydrogenase is inhibited by lithium ; but lithium has
no effect on the activity of other enzymes of glycolysis such as hexokinase
and aldolase (Lallier, 1954).
Research has been undertaken to discover whether the inhibitors of
glycolysis exert vegetalizing effects comparable to those of lithium.
The halogen derivatives of acetic acid such as the monoiodacetic acid,
its amide and bromoacetic acid, inhibit glycolysis at the level of
triosephosphate dehydrogenase. Iodoacetate is very weakly vegetalizing
(Runnström, 1935b). The monoiodacetamide exerts a very strong
cytolytic action on the eggs (Lindahl, 1939). Bromoacetic acid provokes
an increase of primary mesenchyme (Tchakhotine, 1938). This phenomenon may correspond to a weak and atypical vegetalization. DLGlyceraldehyde inhibits glycolysis by interfering with the reaction of
the hexokinase (Lardy et al., 1950). DL-Glyceraldehyde does not provoke
the vegetalization of the sea urchin egg (Needham and Needham, 1940).
Phlorizin inhibits the phosphorylation of glycogen into glucose-1phosphate. It does not have vegetalizing effects (Needham and Needham,
1940). However, these authors point out that the weak solubility of
phlorizin in sea-water must strongly diminish its activity on the sea
urchin egg.
2-Deoxyglucose, an analogue of glucose, inhibits glycolysis. The
blocking appears to take place at the level of phosphohexoisomerase, an
enzyme that catalyses the transformation of glucose-6-phosphate into
fructose-6-phosphate (Sols and Crane, 1954). 2-Deoxyglucose does not
exert vegetalizing effects, and moreover, it does not prevent the
vegetalizing action of lithium (Lallier, 1960b, c).
The inhibition of cytochrome oxidase, the terminal enzyme of the
tricarboxylic acid cycle, by cyanide or carbon monoxide does not exert
vegetalizing effects comparable to those of lithium (Runnström, 1928c;
Hörstadius and Strömberg, 1940). However, Child (1948) and Rulon
(1950) with sodium azide have obtained exogastrulation and definite
vegetalization of larvae. Sodium malonate and selenite inhibit succinic
dehydrogenase, an important enzyme of the tricarboxylic cycle. In
sand-dollar eggs sodium malonate is not vegetalizing and selenite exerts
some radializing effects (Rulon, 1951,1952a).