424 ADVENTURES IN RADIOISOTOPE RESEARCH 



Comment on papers 41 — 43 



In some of their earliest classical investigations, Sc hoe nheimer and Rittenberg 

 using deuterium as an indicator found the half-hfe of fatty acids of the liver of 

 the rat to be from 1 to 2 days. Investigating with Dreyfus the effect of irradiation 

 on the turnover rate of the fatty acids of the liver of mice very shortly after admi- 

 nistration of "C labelled acetate (paper 81), we found the presence in the Uver 

 of a fatty acid fraction having the half- life of some minutes only. No such fraction 

 was found in the fatty acids extracted from the brain or the muscles (paper 39). 

 Beeckmans and Elliot (1951) succeeded in our laboratory in demonstrating 

 that both the saturated and unsaturated fatty acids of the liver contain a short - 

 living fraction, and Swan (1951) could show that we are not faced with only 

 a re-carboxylation of the molecule, but with a renewal of all its carbon atoms. 

 Recently, a short-living fatty acid fraction was found also in the liver of the 

 lat (TovE 1956). 



The half-life of molecules is usually determined by following the incorporation 

 of the tracer into the newly formed molecules. As described in paper 41 we can 

 also determine the half-life of the liver fatty acids by labelling these and following 

 the rate of decrease in their activity. 



References 



L. M. Beeckmans and G. Elliot (1951) Nature 167, 200. 



G. A. Swan (1951) Ark. Kemi 3, 167. 



S. B. TovE, J. S. Andrews and H. C Lucas (1956) J. Biol. Chem. 218, 275. 



