62 



elude the mononucleotides that are soluble in acid. The cells are first extract- 

 ed with TCA and fat solvents. RNA and DNA are extracted from the insoluble 

 fraction with hot sodium chloride. The RNA is hydrolyzed to its constituent 

 mononucleotides, and these are separated on paper by ionophoresis. We have 

 also separated RNA-mononucleotides on a Dowex-1 formate column with essenti- 

 ally the same results. 



POTTER: Is there something special about these cells? 



SHERMAN: No, these were normal yeast cells grown in a synthetic 

 medium containing as many of the cofactors and vitamins as we know. Perhaps 

 growth is not quite as good as it is on a non-synthetic medium but it approaches 

 it at least. 



The cells are irradiated in potassium phosphate buffer, then put into a 

 nonirradiated growth medium containing 2 mc. of P^2 per ml. , and incubated 

 for 1 hour at 30OC. 



CARTER: This represents a 1 hour period of incubation then? Do you 

 have time sequences that show the distribution earlier? 



SHERMAN: No, we are planning to do that. 



BENNETT: Do you have quantitative data for the amount of nucleic 

 acid present? Is it increased or decreased? 



SHERMAN: There is an apparent increase in the amount of RNA in all 

 but the first experiment. DNA does not appear to change significantly. The 

 data are shown in Table 1. Both RNA and DNA were extracted by the method of 

 Ogur (18). The DNA extraction, I think, is not nearly as clean as the RNA ex- 

 traction. I am not as convinced by the DNA values as by the RNA figures. I 

 think the probable error in the RNA determination is smaller than it is in the 

 DNA determination. 



TABLE 1 



RIBOSE AND DESOXYRIBOSE NUCLEIC ACID IN 

 IRRADIATED AND NONIRRADIATED YEAST 



(mg/mg dry wt. of yeast) 100 



Experiment 



RNA 



Control 60,000 r 100, 000 r 



DNA 

 Control 60, 000 r lOO.OOOr 



1 

 2 

 3 

 4 

 5 

 6 

 7 



5.81 

 5.38 



5.38 

 5.50 



5. 25 



6. 78 



0.42 



0.42 



0. 41 



Under these conditions there is not much of an increase in the number 



