128 Alexander Hollaender and George E. Stapleton 



Deletion experiments showed the minimal (Table II) organic 

 requirements to be guanine, uracil, and glutamic or aspartic 

 acids, precursors for ribonucleic acid and/or protein synthesis. 



(A 



i 



O 

 O 



< 



+ 



O 



o 



S 

 -t 

 < 



< 



CD 



100- 



z 

 g 



»- 

 o 



< 



o 



z 



> 

 > 



10- 



KIDNEY 

 TESTES 



LIVER 



INTESTINE 



-1 1 1 



10 100 1,000 



LOG CONCENTRATION (^g/ml) " 



10,000 



Fig. 7. Relative activity of rabbit tissue homogenates ; 

 incubation at 37° C. (Stapleton, Sbarra and Hollaender, 



1955.) 



It seemed of the utmost importance to investigate the 

 effect of preirradiation growth conditions on the survival of 

 cells after irradiation, as well as their response to added 



Plus or minus vitamins, amino acids, purines, and pyrimidines. 



nutritional factors after exposure. Cells were grown in a 

 variety of media including: (1) basal medium — the inorganic 



