TURNOVER RATES DURING FORMATION OF 



PROTEINS AND POLYNUCLEOTIDES IN 



REGENERATING TISSUES 



E, HAMMARSTEN 



The occurrence of a functional interrelation between 

 nucleic acids and proteins during synthesis of these substances 

 in cells has been investigated by many on the basis of 

 Miescher's original discovery in 1872. A group at our 

 laboratory at present engaged with this problem consists of 

 E. Anderson, N. A. Eliasson, E. Hammarsten, U. Lagerkvist, 

 B. Low, P. Reichard, A. Wretlind and S. Aqvist, working in 

 collaboration with B. Thorell and G. Heden at the Institute 

 for Cell Research and G. Ehrensvard at Wenner-Grens 

 Institute. 



We are investigating a possible correlation between the 

 turnover and synthesis of polynucleotides and that of proteins 

 during growth. Glycine marked with ^^N, and in some 

 experiments with ^^C in the methyl and ^*C in the carboxyl 

 groups, was used. The rate of protein turnover was measured 

 by the concentration of isotope in the glycine incorporated 

 in the proteins at different stages of regeneration in rat liver 

 after partial hepatectomy. In the same experiments the 

 polynucleotides were degraded and the rate of their turnover 

 measured by the isotope content in the nitrogenous bases. 



In other experiments hen bone, marrow was used in order 

 to study metabolic changes during growth and differentiation 

 of the blood cells. Results of these experiments will be 

 mentioned here only in so far as they disclose a certain 

 relationship between the isotope content in amino-acids and 

 purine bases. 



The investigation of the relationship between the turnover 

 rates of two different cellular substances will naturally be 



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