BIOCHEMICAL ASPECTS OF ANIMALIZATION AND
VEGETALIZATION IN THE SEA URCHIN EMBRYO
R. LALLIER
Station Zoologique, Centre National de la Recherche Scientifique,
Paris et Villefranche-sur-Mer (A.M.), France
I. Introduction
147
II. Normal Development
148
III. Experimental Study of Morphogenesis
150
A. Definitions
150
B. Experimental Methods
151
C. Heuristic and Practical Value of Operative and Chemical Methods
153
IV. The Gradients
154
V. Respiration and Carbohydrate Catabolism
158
A. Normal Development
158
B. Vegetalization
159
C. Animalization
165
VI. Metabolism of Amino-acids and Proteins
167
VII. Metabolism of Nucleotides and Ribonucleic Acid
171
VIII. Enzymes, Mitochondria and Embryonic Development
173
IX. Biochemical Background of the Gradients of Reduction
178
X. Structural Aspects of Embryonic Determination and Differentiation
183
XI. Conclusion
187
References
191
I. Introduction
The ability of the sea urchin egg to modify its development in a characteristic way under the influence of determined conditions makes it a
specially useful material for the study of the processes of embryonic
differentiation and explains the increasing amount of research devoted
to the study of the morphological and biochemical aspects of normal
development and its experimental modifications. In this paper, only the
chief morphological manifestations will be described, as they serve as an
introduction to the study of the biochemical phenomena that accompany
them. It is these phenomena that will be examined and, without
pretending to give an exhaustive review, we shall try to trace the
evolution of the research and show its present orientation, taking into
147