123 



BENNETT: We have data on adenine with respect to how much of it 

 soes into DNA, RNA and the soluble nucleotide pool that you are speaking 

 aboutt2)(3). I might say that at the X-ray dosages we have given, these data 

 compare with the P^^ - phosphate data for similar tissues and dosages that have 

 been obtained by Dr. Kelly at the University of California. It appears that in a 

 tissue let's say such as bone marrow, which might be a good one to discuss, 

 the amount of adenine-4, 6-cl4 or p32 - phosphate incorporated into DNA is 

 about 5 percent of normal when a mouse is exposed to 1000 r x irradiation, 

 whereas the change of amount of adenine incorporated into the RNA or the ade- 

 nylic acid nucleotides is small -- a factor of 2 at the most. 



CARTER: In other words, if you were to reconstruct your data you 

 would say that adenine enters a pool of intermediates, and that this reaction is 

 essentially uninfluenced by the irradiation? 



BENNETT: A pool of intermediates as determined by nucleotides, 

 such as 5 - adenylic acid, ADP, ATP, etc. . and incorporation into RNA is un- 

 interrupted while DNA incorporation is inhibited extensively. The amount of 

 adenine removed from this pool and incorporated into RNA in some tissues is 

 actually increased, but it is not changed to anywhere near the same degree that 

 the amount incorporated into the DNA is changed. 



DUBOIS: 1000 r is a pretty big dose. 



BENNETT: We have not done experiments using any smaller dosages 

 which may be why our data do not agree with that of Lavik and Harrington. 

 Other reasons for the discrepancy might also be suggested. 



DUBOIS: What time after irradiation? 



BENNETT: We have done experiments at numerous times from 2 

 hours to 3 days afterwards. The time interval during which the adenine or 

 phosphorus was in the mouse was 2 hours; in other words, almost as short a 

 time as possible. The effect of irradiation changes with time; if one does a 

 long-term experiment, one is integrating results in a fashion which because 

 of all these pool factors, one just does not know about. So it seemed advan- 

 tageous to us to do the experiment over as short a time interval as possible and 

 at as many intervals as feasible. 



CARTER: You see the dilemma you are faced with in any interpreta- 

 tion; that is, either you must say that the desoxynucleic acid is metabolically 

 heterogenous -- 



CHARGAFF: That has been shown by Bendich and others, at least to 

 a certain extent. 



CARTER- That is the point to be made here. There are types of 

 molecules or regions in the molecules that turn over at fantastically different 

 rates. Bendich has shown by a fractionation technic two clear desoxynucleic 

 acid fractions that turn over at widely different rates -- 



CHARGAFF: The trouble is, his fractions are not analyzed. 



SPIEGELMAN: How are these separated? 



CARTER: They are separated by salt and alcohol fractionations. I 



