66 



BENNETT: I might point out that this is somewhat in contrast to what 

 one gets in mice in adenine experiments of a similar type. Here, the main ef- 

 fect to be noted is on the DNA, and small but varying effects on RNA are ob- 

 served, depending upon the tissue and the time after irradiation. 



SHERMAN: I don't know that I would go along with that exactly because 

 the few experiments we have made with mouse liver go along quite like this. 



BENNETT: I have done numerous experiments using adenine in mice, 

 but perhaps tomorrow is a more appropriate time to discuss these results fur- 

 ther. 



SHERMAN: I think Dr. Jones also showed that there was an increase 

 in the incorporation of p32 i^ cytoplasmic RNA. 



JONES: Yes, that is a post-irradiation change we have noted. 



BENNETT: But the effect of X irradiation on the incorporation of p^^- 

 phosphate or adenine into RNA is small compared with the immediate effect ob- 

 served on the incorporation into DNA. It is a factor of 2 at the most on RNA 

 whereas the incorporation of p32-phosphate or adenine-C^4 into the DNA of the 

 liver or bone marrow is decreased to 5 to 10 percent of that in a normal animal. 



These results are similar whether they are carried out with adenine-4, G-C^^ or 

 p32 



SHERMAN: In our experience, at least, the DNA story isn't as good 

 as the RNA story from the point of view of getting out DNA that is not contami- 

 nated with other phosphorus fractions. 



KAMEN: From the standpoint of continuity, I remember that we made 

 much last year of the experiments that Kellner did on ultraviolet irradiation of 

 E. coli followed by reactivation with visible light. Kellner's thesis was that 

 maybe the reactivation phenomenon was a better, more sensitive criterion for 

 singling out real irradiation effects from those that occur in the more drastic 

 case of X-ray, and Kellner's conclusion was that there was an inhibition of DNA 

 synthesis within a minute after cessation of UV irradiation. 



Now with the X-ray, the general burden appears to be that it is the RNA 

 that is activated and accelerated and that the DNA stands still. I am a little 

 worried about how this fits together now. I have not seen any more from Kell- 

 ner's laboratory about this work. I am wondering if anybody knows how that has 

 developed since a year ago. 



SHERMAN: It is my impression from the experiments that we have 

 done, that the pattern of p32 activity in the various RNA nucleotides is a fairly 

 variable one. In many instances with 100,000 r, uridylic acid seems to have the 

 largest part of the activity, and there are experinnents in which this is exagge- 

 rated. (Figure 4). 



In the 60,000 r experiment and in others, cytidylic, adenylic, and 

 guanylic acids have about the same activity, while the uridylic acid appears to be 

 short-changed. In all cases, however, the pattern is different from the pattern in 

 the nonirradiated cells. This suggests that the mononucleotides may be put to- 

 gether differently in irradiated cells than in nonirradiated cells. 



CARTER: It means that they are entering at a different rate, not that 

 they are put together differently. 



