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DISCUSSION 



Davidson: There is one point I should Uke to ask in connection with 

 technique. How, if you are working to a matter of minutes, can you 

 know when to take your sample ? By the time you have got your DNA 

 estimation it is too late. 



Spiegelman: We take our 10-minute samples blindly. The plateaus are 

 30 minutes long and sampling at 10-minute intervals is adequate to 

 exhibit them. 



Gale: Is there no change in the turbidity associated with the stepwise 

 increase in the DNA? 



Spiegelman: You do not see cycling of overall protein synthesis but 

 there is apparent cycling of induced enzyme formation. There is a very 

 interesting possibility here which I think fits in with the hypothesis 

 proposed by Gale, namely that the RNA templates of the induced 

 enzymes are unstable. They would therefore require recharging from 

 the nucleus, and in this event formation of such proteins would be more 

 closely tied to nuclear events than would constitutive protein formation. 

 However, it is not possible at the present time to make any statement 

 that such a difference is actually real. It should be noted that the 

 absence of cycling in the constitutively formed proteins does not mean 

 that none exist, because one can imagine that they are all cycling but 

 are out of phase with each other; and so the effect is cancelled out. 

 What one has to do is follow the synthesis of particular constitutive 

 proteins. We have been looking for such, but we haven't as yet found 

 any that possess all the properties that would make them suitable 

 material for study. 



Alexander: Does the actual numerical increase in bacteria also follow a 

 plateau if you take them out ? 



Spiegelman: No, not in this system. That is difficult to do because this 

 is multicellular ; each cone is not a single cell, we have had to shake them 

 apart to get good correspondence. 



RAD. 8 



