SPECIFIC MECHANISMS OF PROTEIN SYNTHESIS 



AND INFORMATION TRANSFER IN THE 



DEVELOPING CHICK EMBRYO* 



H. R. Mahler, H. Walter, A. Bulbenko and D. W. Allmann 



Department of Chemistry, Indiana University, Bloomington, Indiana 



Abstract — Some preliminary data on precursors and pathways of protein biosynthesis in 

 chick embryos have been presented. The tentative conclusions stated are: 



1. Egg white proteins are not utilized for the synthesis of embryonic proteins up to and 

 including the ninth day. Soluble proteins added to the yolk are incorporated effectively, and 

 preferentially to some of the yolk proteins proper. 



2. Proteins, peptides and amino acids injected into the yolk sac are incorporated at 

 approximately equal rates. Considering the relative available pool sizes of the various pre- 

 cursors present in the egg, added proteins have to be regarded as the preferred amino acid 

 source of embryonic proteins. 



3. A common precursor formed efficiently from proteins and relatively slowly from added 

 amino acids and peptides is considered a likely intermediate in the process. 



4. Homogenates of adult organs injected into embryos can be used to elicit a response 

 previously reported for organ transplants, i.e. the apparently specific transfer of labeled 

 material from donor organs to the corresponding organ in the embryonic host. The super- 

 natant fraction of the cytoplasm appears to be, at least in part, responsible for the results 

 observed. 



I. INTRODUCTION 



It is the purpose of this contribution to describe, in brief, some preHminary 

 experiments on a controlled biosynthetic activity, namely, the precursors and 

 pathways of protein formation. It differs from most of the papers in this 

 symposium in dealing with phenomena rather than with concepts and in the 

 absence of any attempt to establish a functional correlation between these 

 biological phenomena and information-theoretical abstractions. It shares 

 with other papers in this volume the properties of being highly tentative, 

 and in presenting data and comments on a subject to which it is felt information 

 theory should eventually make significant contributions. With the hope 

 that arrival of that time might be hastened and that thought and discussion 

 might be stimulated, our data are presented for consideration. Some of the 

 results are derived from single experiments only and thus lack further con- 

 firmation. All of the approaches and conclusions reported are still under active 

 investigation and thus subject to revision and modification. 



Embryos were chosen for the experiments since their cells exhibit two 

 fundamental and related properties, both apparently controlled by the nuclear 



* The investigations reported have been supported by grants-in-aid of the National 

 Heart Institute, National Institutes of Health, U.S. Public Health Service (Grant No. H 2177) 

 and of the National Science Foundation. This article is contribution No. 746 from the 

 Department of Chemistry, Indiana University. 



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