102
E N R I C O U R B A N I
question of protein synthesis (Fruton, 1941, 1950, 1954); embryonic
materials undoubtedly lend themselves to this type of research.
In a review by Gustafson (1954) of the enzymatic aspects of embryonic
differentiation, this problem is considered with reference to co-enzyme
synthesis and to the role played by mitochondria in these phenomena.
In the last chapter of his recent book, Brächet (1960a) clearly outlines
the progress made by biochemical studies on differentiation, and indicates the objectives which still lie ahead of us. We refer our reader to
this publication for other aspects of the many problems which we have
merely outlined or omitted.
In conclusion, it may be stated that epigenesis of enzymatic activity
concurrently with differentiation and embryonic development is highly
probable. On the other hand, it is difficult to determine the extent
and limitations of the possible synthesis of newly formed enzymes at
given stages of the developmental cycle. On the basis of our knowledge
of protein synthesis during embryonic development and of the existence
of adaptive enzymes, we feel inclined to support the hypothesis that
new enzymatic molecules are created during ontogenesis. This assumption opens interesting fields of research for embryology and zoological
chemistry.
Acknowledgement
It is a pleasure to express my obligation to Prof. J. Brächet for his
invitation to write the present paper.
References
Adolph, E . (1931). Biol. Bull., Woods Hole 61, 376.
Agrell, I. (1947). Ada physiol. scand. 14, 317.
Agrell, I . (1949). Ada physiol. scand. 18, 355.
Agrell, I. (1953). Ada physiol. scand. 28, 306.
Allen, B . M. (1919). J. Morph. 32, 489.
A r t o m , C. (1906). Biol. Zbl. 26, 1.
Atlas, M. (1938). Physiol. Zool. 11, 278.
Baffoni, G. M. (1960). Riv. Biol. 53, 293.
Baldisserotto, A. a n d Ugurgieri, B . (1958). R. C. Accad. Lined 25, 81.
Baldwin, E . (1937). 'An I n t r o d u c t i o n to Comparative Biochemistry', Cambridge
University Press.
Ballentine, R. (1940). J . cell. comp. Physiol. 16, 39.
Barfurth, D . (1887). Arch. mikr. Anat. 29, 1.
Barigozzi, C. (1942). Chromosoma 2, 251.
Barnes, M. R. (1939). Anat. Rec. 75 (Suppl.), 114.
B a r t h , L. G. (1946). J . exp. Zool. 103, 463.
B a r t h , L. G. a n d B a r t h , L. (1954). 'The Energetics of Development. A S t u d y of
Metabolism in t h e Frog Egg', Columbia University Press, New York.
B a r t h , L. G. a n d Jaeger, L. (1947). Physiol. Zool. 20, 133.
B a r t h , L. G. a n d Jaeger, L. (1950). J. cell. comp. Physiol. 35, 413 a n d 437.
E N R I C O U R B A N I
question of protein synthesis (Fruton, 1941, 1950, 1954); embryonic
materials undoubtedly lend themselves to this type of research.
In a review by Gustafson (1954) of the enzymatic aspects of embryonic
differentiation, this problem is considered with reference to co-enzyme
synthesis and to the role played by mitochondria in these phenomena.
In the last chapter of his recent book, Brächet (1960a) clearly outlines
the progress made by biochemical studies on differentiation, and indicates the objectives which still lie ahead of us. We refer our reader to
this publication for other aspects of the many problems which we have
merely outlined or omitted.
In conclusion, it may be stated that epigenesis of enzymatic activity
concurrently with differentiation and embryonic development is highly
probable. On the other hand, it is difficult to determine the extent
and limitations of the possible synthesis of newly formed enzymes at
given stages of the developmental cycle. On the basis of our knowledge
of protein synthesis during embryonic development and of the existence
of adaptive enzymes, we feel inclined to support the hypothesis that
new enzymatic molecules are created during ontogenesis. This assumption opens interesting fields of research for embryology and zoological
chemistry.
Acknowledgement
It is a pleasure to express my obligation to Prof. J. Brächet for his
invitation to write the present paper.
References
Adolph, E . (1931). Biol. Bull., Woods Hole 61, 376.
Agrell, I. (1947). Ada physiol. scand. 14, 317.
Agrell, I . (1949). Ada physiol. scand. 18, 355.
Agrell, I. (1953). Ada physiol. scand. 28, 306.
Allen, B . M. (1919). J. Morph. 32, 489.
A r t o m , C. (1906). Biol. Zbl. 26, 1.
Atlas, M. (1938). Physiol. Zool. 11, 278.
Baffoni, G. M. (1960). Riv. Biol. 53, 293.
Baldisserotto, A. a n d Ugurgieri, B . (1958). R. C. Accad. Lined 25, 81.
Baldwin, E . (1937). 'An I n t r o d u c t i o n to Comparative Biochemistry', Cambridge
University Press.
Ballentine, R. (1940). J . cell. comp. Physiol. 16, 39.
Barfurth, D . (1887). Arch. mikr. Anat. 29, 1.
Barigozzi, C. (1942). Chromosoma 2, 251.
Barnes, M. R. (1939). Anat. Rec. 75 (Suppl.), 114.
B a r t h , L. G. (1946). J . exp. Zool. 103, 463.
B a r t h , L. G. a n d B a r t h , L. (1954). 'The Energetics of Development. A S t u d y of
Metabolism in t h e Frog Egg', Columbia University Press, New York.
B a r t h , L. G. a n d Jaeger, L. (1947). Physiol. Zool. 20, 133.
B a r t h , L. G. a n d Jaeger, L. (1950). J. cell. comp. Physiol. 35, 413 a n d 437.