IV 



RNA AND GROWTH PROTEIN SYNTHESIS 



279 



amino acid. The separated fractions were at least 100 times as effective as staphylo- 

 coccal RNA. Gale's (1955) conclusion is "that the whole RNA complex is not 

 necessary for the incorporation of any particular amino acid, and that RNA can 

 be replaced by small fragments obtained by ribonuclease digestion of the whole 

 RNA structure". The significance of these important observations for present 



< • 



;^.s-"':m 





%ll 









:>♦ • -^ ■-'-'•* » 



f^- 







m^ 





.^ierlL'-Jt^l^^" -kl*^ 



• *'. --^Put- 



Fig. 5. Autoradiograph after incorporation of labelled phenylalanine into onion roots, 

 a: normal root; b: root treated in vivo during 3 h. with ribonuclease (i mg/ml). 



theories on the mechanisms of protein synthesis will be discussed later (p. 285). 



The experiments of Gale and Folkes (1954, 1955a, 1955b) raise a new and im- 

 portant question for the biologist: is it possible to inhibit growth and protein 

 synthesis in living cells or organisms by ribonuclease treatment? 



This problem has been extensively studied in the author's laboratory during 

 the past two years: starting from the observation by Kaufmann and Das (1954, 

 1955), that mitotic abnormalities occur in onion root-tips immersed in ribonu- 

 clease solutions, it was decided to study the biochemical effects of ribonuclease on 

 various cells. Only the main results will be summarized here. 



Literature p. 2gg 



