670 ADVENTURES IX RADIOISOTOPE RESEARCH 



AMOUNT OF NUCLEIC ACID FORMED DAILY IN THE DIFFERENT 



ORGANS OF THE RAT 



If we assume that the labelled desoxyribose nucleic acid found in an 

 organ is synthesized in the organ in question, we can estimate from 

 the data of Table 2 and the desoxyribose nucleic acid content of the 

 organs the total amount of desoxyribose nucleic acid which is built up 

 daily in the different organs. Data are available on the total nucleic 

 acid content of the organs of the rat. These data are given in Table 3. 

 With the exception of the figure stated for the nucleic acid content 



Table 3. — Upper Limit of the Desoxyribose Nucleic 

 Acid Content of Different Organs of the Rat 



Desoxyribose nucleic acid 

 Organ \ t. ^ , s 



content (mgm per gm) 



Muscle 



Heart 



Brain 



Kidney 



Testes(i) 



Mucosa of the small intestine 



Liver 



Spleen 



Thymus(2) 



1.4 

 1.4 

 2.5 

 3.3 

 5.7 

 5.1 

 6.5 



10 



30 



•'> Horse testes. (Javiilier and Allaire, 1926.) 



'■^1 Horse thymus. For calf thymus, 36 was found. (Javillier and Allaire, 1926.) 



of the intestinal mucosa, they are taken from a paper by Javillier 

 et al. (1928). These workers state the nucleic acid P content of the 

 tissue investigated ; we multiplied their figures by 12 to arrive at 

 the nucleic acid content. As no data were available for the nucleic acid 

 content of the mucosa of the intestine, we determined the desoxyribose 

 nucleic content of the mucosa small intestine by using Dische's method 

 (1930) in a slightly modified form, as applied by Vowles (1940). This 

 method is based on the fact that, when heating a solution of desoxyri- 

 bose nucleic acid in the presence of diphenylamin, acetic acid and sul- 

 phuric acid, a violet colouring is obtained, the intensity of the colour 

 being proportional to the concentration of the nucleic acid. As standard 

 preparation we used a thymus nucleic acid preparation kindly presented 

 us by Professor Hammaesten. As the reaction used is not strictly spe- 

 cific for desoxyribose, the figure obtained has also to be considered an 

 upper limit of the desoxyribose nucleic acid content of the intestinal 

 mucosa. 



