ANIMALIZATION AND VEGETALIZATION
189
Lallier (1958c) has suggested that animalization and vegetalization
result from changes in the configuration of proteins. According to the
modern concept of protein structure, the biological properties of proteins
depend on their configuration, that is to say on the mode of arrangement
of their peptide chains. Their configuration is also responsible for the
chemical affinity of proteins. Very active animalizing agents such as
zinc ions and polysulphonic dyes have an affinity for the more vegetal
part of the embryo (Lallier, 1956b, 1957a). This phenomenon indicates
some difference in the configuration of proteins between the vegetal and
animal parts of the embryo. It may suggest that the animalizing agents,
because of their affinity to proteins, are able to induce changes in the
configuration of proteins. Vegetalizing agents such as lithium or
Phenazone would act by disturbing the hydrated layer of the protein
molecules. The observation that chloramphenicol, an inhibitor of
protein synthesis, exerts vegetalizing effects (Lallier, 1961c) again
emphasizes the importance of protein synthesis in the processes of
embryonic determination and differentiation.
XI. Conclusion
Differentiation implies the elaboration of cellular constituents and
their organization into specialized structures. These phenomena,
together with the supply of energy necessary for synthetic processes,
depend on the existence of differentiated nuclear and cytoplasmic
structures. With regard to the analysis of the development of the sea
urchin egg, only the processes of energy supply and later, some synthetic
processes, have been studied to any extent.
The energy necessary for the development of the sea urchin egg is for
the most part supplied by carbohydrate catabolism. This degradation
proceeds by glycolysis and the tricarboxylic acid cycle. The hexosemonophosphate shunt system is also functional. Carbohydrate catabolism is disturbed in the vegetalized and animalized embryos. However,
the inhibitors of glycolysis and respiration do not exert morphogenetic
effects comparable to those obtained with animalizing and vegetalizing
agents. These observations suggest that the morphogenetic action of the
animalizing and vegetalizing agents is not related to their effect on the
activity of carbohydrate catabolism, but depends on a more direct
action on the formation of enzymatic proteins. Gustafson (1955) has
remarked, with respect to lithium at least, that the effects of this agent
on isolated enzymes appear weaker than on whole cells. This remark,
together with the inhibition by lithium of the rise of activity of certain
enzymes during development also suggests an inhibitory action on the
synthetic processes of enzymatic proteins.
G
189
Lallier (1958c) has suggested that animalization and vegetalization
result from changes in the configuration of proteins. According to the
modern concept of protein structure, the biological properties of proteins
depend on their configuration, that is to say on the mode of arrangement
of their peptide chains. Their configuration is also responsible for the
chemical affinity of proteins. Very active animalizing agents such as
zinc ions and polysulphonic dyes have an affinity for the more vegetal
part of the embryo (Lallier, 1956b, 1957a). This phenomenon indicates
some difference in the configuration of proteins between the vegetal and
animal parts of the embryo. It may suggest that the animalizing agents,
because of their affinity to proteins, are able to induce changes in the
configuration of proteins. Vegetalizing agents such as lithium or
Phenazone would act by disturbing the hydrated layer of the protein
molecules. The observation that chloramphenicol, an inhibitor of
protein synthesis, exerts vegetalizing effects (Lallier, 1961c) again
emphasizes the importance of protein synthesis in the processes of
embryonic determination and differentiation.
XI. Conclusion
Differentiation implies the elaboration of cellular constituents and
their organization into specialized structures. These phenomena,
together with the supply of energy necessary for synthetic processes,
depend on the existence of differentiated nuclear and cytoplasmic
structures. With regard to the analysis of the development of the sea
urchin egg, only the processes of energy supply and later, some synthetic
processes, have been studied to any extent.
The energy necessary for the development of the sea urchin egg is for
the most part supplied by carbohydrate catabolism. This degradation
proceeds by glycolysis and the tricarboxylic acid cycle. The hexosemonophosphate shunt system is also functional. Carbohydrate catabolism is disturbed in the vegetalized and animalized embryos. However,
the inhibitors of glycolysis and respiration do not exert morphogenetic
effects comparable to those obtained with animalizing and vegetalizing
agents. These observations suggest that the morphogenetic action of the
animalizing and vegetalizing agents is not related to their effect on the
activity of carbohydrate catabolism, but depends on a more direct
action on the formation of enzymatic proteins. Gustafson (1955) has
remarked, with respect to lithium at least, that the effects of this agent
on isolated enzymes appear weaker than on whole cells. This remark,
together with the inhibition by lithium of the rise of activity of certain
enzymes during development also suggests an inhibitory action on the
synthetic processes of enzymatic proteins.
G