. Biological structure and function; proceedings. Biochemistry; Cytology. CHAIRMAN S INTRODUCTION 471 The vectors of Fig. 3 may primarily represent pathways of protein synthesis. As experiments with labelled precursors show, incorporation of for example ['^C]-leucine into proteins runs parallel with the incorporation of [^^C]-adenine into ribonucleic acid, cf. Markman [18]. It is evident that the ribonucleic acid plays the same fundamental role in protein synthesis in the sea urchin material as elsewhere. As far as it is possible to resolve the sites of incorporation, that of the ribonucleic a
. Biological structure and function; proceedings. Biochemistry; Cytology. CHAIRMAN S INTRODUCTION 471 The vectors of Fig. 3 may primarily represent pathways of protein synthesis. As experiments with labelled precursors show, incorporation of for example ['^C]-leucine into proteins runs parallel with the incorporation of [^^C]-adenine into ribonucleic acid, cf. Markman [18]. It is evident that the ribonucleic acid plays the same fundamental role in protein synthesis in the sea urchin material as elsewhere. As far as it is possible to resolve the sites of incorporation, that of the ribonucleic acid precursor ( [^^C]- adenine) occurs primarilv in the nuclei. It seems thus probable that the synthesis of ribonucleic acid on which the protein svnthesis is dependent occurs in the nucleus. I trust that the question about the site of ribonucleic acid formation will be more deeply discussed in the paper by Dr. Prescott who refers to another material, viz. amoebae. ft An Veg AP>^. •-VP Fig. 4. Diagram of the vegetal and animal vectors over the whole embryo, VP vegetal pole, AP animal pole. Vectors representing the opposite synthetic pathways on the same embryonic level form the same angle with the vegetal- animal axis VP-AP. In this context anabolic processes other than ribonucleic acid and protein synthesis must be disregarded. It may only be noticed in passing that my colleague Immers found also indications of a parallelism between incorporation of amino acids into proteins and an incorporation of ["^'S]- sulphate into mucopolysaccharides. Figure 4 gives a diagram of the vegetal and the animal \ectors of ribonucleic acid and protein synthesis over the whole embryo from the vegetal (VP) to the animal pole (AP). The levels in the embryo are given by the angles that the vectors form with the baseline (AP-VP). There is no need to emphasize how grossly simplified this picture is. Nevertheless it may be of some use. Different kinds of ribonucleic acids must be formed
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