416 R. M. S. SMELLIE 



the nature of this effect, Ahlstrom et al}^'' have transfused the blood of an 

 irradiated rabbit into an untreated aninal. The results of this experiment 

 were not conclusive, but it was found that in the kidney of the recipient 

 animal the uptake of P^^ by the DNA was lowered by the transfusion, as 

 might be expected if some humoral agent were present. 



The possibility that the effect of irradiation on DNA metabolism is 

 concerned only with the phosphorylation processes has been ruled out by 

 the work of Hevesy,"* who found that the incorporation of acetate-1-C^^ 

 into the DNA purines was reduced by irradiation to about the same extent 

 as the reduction in P^^ incorporation. Abrams"^ in similar experiments using 

 glycine- 1-C^^ has found that the incorporation of radioactive carbon into 

 the PNA and DNA purines of rabbit bone marrow and intestine, and of 

 rat intestine, was greatly reduced by X-irradiation. Harrington and Lavik^^ 

 have observed that while whole body irradiation partially inhibits the 

 incorporation of small-molecule precursors into the DNA of rat thymus, 

 the uptake of labeled adenine is not affected. 



The effects of X-rays on the metabolism of the PNA of the nucleus and 

 cytoplasm as well as on the DNA of rat liver cells has been studied by 

 Payne et o/.,'^" who have shown in two strains of rats and also in mice that 

 the incorporation of P^- into the cytoplasmic PNA was increased aftei 

 irradiation, while the uptake of isotope by nuclear PNA and DNA was 

 greatly diminished. 



Recently Vermund et al}'^^ have studied the effects of X-irradiation on 

 the incorporation of P^- into the nucleic acids of transplanted mouse mam- 

 mary carcinomata. They found that irradiation caused a marked fall in 

 the uptake of the isotope by the DNA of the irradiated tumor. A less- 

 marked inhibition of DNA metabolism in a shielded tumor in the same 

 animal was also observed. No statistical evidence was found however to 

 show that the irradiation has any action on the metabolism of PNA of the 

 tumor nuclei or cytoplasmic fractions. 



2. The Effect of Antibiotics on Nucleic Acid Metabolism 



a. Penicillin 



In 1947, Krampitz and Werkman'22 showed that in high concentrations 

 penicillin brought about inhibition of the oxidation of the pentose con- 



"' L. Ahlstrom, H. von Euler, G. C. Hevsey, and K. Zerahn, Arkiv Kemi, Mineral. 



Geol. 23A, 1 (1946). 

 "8 G. C. Hevesy, Nature 163, 869 (1949). 

 "' R. Abrams, Arch. Biochem. 30, 90 (1951). 

 >2» A. H. Payne, L. S. Kelly, and C. Entenman, Proc. Soc. Exptl. Biol. Med. 81, 698 



(1952). 

 '^' H. Vermund, C. P. Barnum, R. A Huseby, and K W. Stenstrom, Cancer Research 



13, 633 (1953). 

 '" L. O. Krampitz and C. H. Werkman, Arch. Biochem. 12, 57 (1947). 



