RENEWAL OF DESOXYRIBO NUCLEIC ACIDS 679 



Assuming the spleen to weigh 0.8 gm, both the amount of polydesose 

 nucleotide P and that of polydesose nucleotide P formed and still present 

 in the spleen works out to be about 20 microgram. 



Sumiuary 



Labelled sodium phosphate is administered to rats and after the lapse of 2 

 hours the specific activity of the ribo-nucleic acid phosphorus and that of the 

 desoxyribo-nucleic acid phosphoinis determined. 



In the hver the specific activity of the ribo-nucleic acid P is found to be 33 

 times larger than the specific activity of the desoxyribo-nucleic acid P. In the 

 course of 2 hours about 0.1 and 3.3 per cent respectively of these compounds 

 were formed. 



In the intestine and in the spleen in which the specific activity of the desoxy- 

 ribo-nucleic acid is found to be about 20 times larger than the corresponding value 

 in the liver, the specific activity of the ribo-nucleic acid phosphorus is only 2 to 3 

 times larger than the corresponding value of the desoxyribo-nucleic acid phos- 

 phorus. 



The ribo- and the desoxyribo-nucleic acid phosphorus extracted from the total 

 rat have a very similar specific activity to the corresponding phosphorus extracted 

 from the intestine. In the total rat the difference in the rate of formation of the two 

 types of nucleic acid is not very pronounced. In a rat weighing 200 gm approxima- 

 tely about 2 mgm desoxyribo-phosphorus and 3 mgm ribonucleic acid phosphorus 

 are incorporated in the couree of 2 hours. 



References 



L. Ahlstrom, H. v. Euler and G. Hevesy (1944). Sv. Vet. Akad. Ark. Kemi 



19, No. 9. 

 E. Andreasen and J. Ottesen (1944) Acta Path. Microbiol. Scand. Suppl. 54. 

 E. Andreasen and J. Ottesen (1945) Acta Physiol. Scand. 10, 258. 

 A. M. Brtjes, M. Tracy and W. E. Cohn (1944) J. hiol. Chem. 155, 619. 

 T. Caspersson (1940) Chromosoma 1, 562. 

 I. L. Chaikoff (1942) Physiol. Rev. 22, 291. 



G. Hevesy and J. Ottesen (1943) Acta Physiol. Scand. 5, 237. 

 R. Schoenheimer, S. Ratner and D. Rittenberg (1939) J. biol. Chem. 130, 



703. 

 H. Tarver and C. L. A. Schmidt (1942) Ihid. 146, 69. 



