THE NUCLEIC ACID CONTENT OF TISSUES AND CELLS 49 



and Willms^^* have measured the PNA and DNA in splenic lymphocytes 

 of the G57 strain of black mice, and in samples of bone marrow from 

 leukemic patients, and propose on the basis of rather few results, that 

 there are a series of 'fixed relationships' for the ratios PNA-P/DNA-P in 

 the various cells. 



Although fresh-water planarian worms contained only 14% of their 

 original total nitrogen after 60 days' starvation, there was no significant 

 change in their DNA content.^^* An earlier report by Logan^^^ that in- 

 creases in PNA and DNA occurred in the proximal as well as the distal 

 portion of a crushed sciatic nerve has been supported by the confirmation 

 of increased cellularity in both segments.^^^ Protein depletion^^* and thia- 

 mine deficiency^^^ produced similar effects on the total nucleic acid con- 

 centrations in the sciatic nerve, although the authors have complicated 

 interpretation by introducing weight controls (younger animals of same 

 weight as animals on deficient diet) in addition to the usual "age" controls. 

 The deficient diets had little or no influence on the nucleic acid concen- 

 trations if comparison Avas made with age controls. 



Hypoxia, produced by an oxygen concentration of 7.75%, caused only 

 slight increases in DNA concentration of rat bone marrow and spleen, but 

 the spleen weight increased by 175%.^*" By growing E. coli and Clostridium 

 welchii in normal and magnesium-deficient media, Webb^*' has been able 

 to show that DNA remains constant in amount in the normal free cells 

 (2.32 X 10~' pg./cell) or in the unit cells of the filamentous forms occurring 

 in Mg-deficient medium (2.36 X 10"^ pg./cell). He also found lower ratios 

 of acid-soluble nitrogen and protein nitrogen to the DNA-P in the Mg- 

 deficient organisms. 



Fonnesu and Severi^®^ experimentally produced "cloudy swelling" of 

 kidney cells by injecting Wistar strain rats with S. typhimurium toxin or 

 mercuric chloride, or by ligaturing the renal pedicle, and showed that the 

 histological changes were accompanied by a decrease in the total amounts 

 of DNA per kidney. Suzuki^*^ treated rabbits with methylthiouracil and 



2" M. L. Menten and M. Willms, Cancer Research 13, 733 (1953). 



2" E. Hoff-J0rgensen, E. L0vtrup, and S. L0vtrup, /. Eitibnjol. Exptl. Morphol. 1, 



161 (1953). 

 2" J. E. Logan, Can. J. Med. Sci. 30, 457 (1952). 



2" J. E. Logan, R. J. Rossiter, and M. L. Barr, J. Anat. 87, 419 (1953). 

 "8 W. A. Mannell and R. J. Rossiter, Brit. J. Nutrition 8, 44 (1954). 

 "9 W. A. Mannell and R. J. Rossiter, Brit. J. Nutrition 8, 56 (1954). 

 28" W. A. Rambach, J. A. D. Cooper, and H. L. Alt, Science 119, 380 (1954). 

 2«' M. Webb, Science 118, 607 (1953). 



"2 A. Fonnesu and C. Severi, Brit. J. Exptl. Pathol. 34, 341 (1953). 

 2" N. Suzuki, Japan. J. Physiol. 3, 279 (1953). 



