67 



BENNETT: It depends on your pool size. You don't have data, I sup- 

 pose, on the amount of soluble nucleotides of these derivatives in yeast. This 

 sort of data would be most important if they are intermediates in the formation 

 of nucleic acids. You can get variable amounts. 



POTTER: The specific activity of all the nucleotide precursors in the 

 acid soluble pool is different, because all of those nucleotides are in equilibrium 

 with all of the coenzymes and they are mixed in different ways, so you can have 

 very remote effects. 



SHERMAN: But this seems to be a variable thing from one experiment 

 to another. 



POTTER: But it affects your interpretation very much. You must 

 avoid the interpretation that the nucleic acid is being put together differently. 



COHN: One wonders what these would look like at a different time, at 

 30 minutes or at 3 hours. 



SHERMAN: Forssberg and I (22) did a series of experiments in which 

 the mice were killed 5 minutes after injection of P^^. we compared the specific 

 activities of phosphorus in inorganic o-phosphate, acid labile phosphate, the 7-. 

 minute hydrolyzable fraction, and the total acid soluble phosphate. A marked 

 increase was seen in the inorganic-phosphate fraction and in the acid labile phos- 

 phate immediately after exposure to 800 r. The activity of these fractions tend- 

 ed to return to the control values 60 minutes after irradiation but they were still 

 significantly higher 24-hours later. The 7-minute hydrolyzable fraction in- 

 creased in activity over the 24-hour period. 



BENNETT: What organ? 



SHERMAN: Liver. 



BENNETT: I think we should distinguish between organs because our 

 experience is that every organ is entirely different. 



SHERMAN: The ommission was an oversight. The acid labile fraction 

 is possibly inorganic pyrophosphate. It was separated from inorganic o-phos- 

 phate by the method of Ernster, Zetterstrohn and Lindberg (23). 



The analysis scheme does not give a clean separation of acid labile 

 phosphate because under the conditions of hydrolysis of acid labile phosphate, 

 about 10 percent of the ATP in the extract is also hydrolyzed. Therefore, the 

 acid labile fraction is diluted to a considerable extent by acid soluble nucleotide 

 P. If 10 percent of the ATP in the extract is hydrolyzed, this can contribute 

 as much as 50 percent of the phosphate found in the acid labile fraction. In spite 

 of that, there is a marked difference in the activities of these 2 fractions in the 

 irradiated animals. 



POTTER: Was the P^^ given intravenously? 



SHERMAN: It was given intrapleurally since there is probably a faster 

 uptake of p32 from the lung than from the peritoneal cavity. 



In muscle, the story is quite different. In order to get enough labeled 

 phosphorus into the muscle to determine conveniently the activity in the various 

 fractions, we had to wait 30 minutes after injection before sacrificing the ani- 



