RNA AND CONTROL OF CELLULAR PROCESSES 131 



Addendum 



During tlie discussions at the S)mposium, I was made aware of 

 two pieces of researcli wliicli mav clarify manv puzzling phenomena 

 observed in RNA formation. First, W. S. Vincent reported that over 

 80 per cent of nucleolar RNA of starfish nucleoli consists of "soluble 

 RNA. ' This would explain independent and high production rate 

 of RNA in nucleoli. Second, French workers in Monod's laboratory, 

 as a result of experiments with ^-galactosidase, believe now that a 

 major part of ribosome RNA does not carry genetic information, but 

 serves as a "workbench" for the action of geneticallv determined 

 "messenger" RNA. The total capacity of protein formation in the 

 cell would thus depend on the amount of ribosome RNA present, 

 while the kind of proteins formed would depend on the presence of 

 specific "messenger" RNA. Messenger RNA has a high turnover 

 and is supposed to function in the formation of only one or few pro- 

 tein molecules. The ribosomal "workbench" RNA may still be syn- 

 thesized in the nucleus, or nucleolus, but if it does not carry any 

 genetic information, its formation in the cytoplasm could be possible. 

 Such concepts would help to explain cytoplasmic RNA synthesis, if 

 thiis is proved to exist at all in a normal cell. 



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