32. THE NUCLEIC ACIDS OF MICROORGANISMS 



183 



TABLE XII 



DNA Composition of Original Intestinal Bacteria and Their 



Experimentally Produced Forms* 



* Taken from A. S. Spirin, A. N. Belozersky et al., Biokhimiya 23, 154 (1958). 



The similarity of alkali-producing forms with respect to their properties is 

 accompanied by the similarity of DNA composition in alkali-producing 

 forms produced from different original cultures by very different treatment 

 [strongly marked GC-type, (G + C)/(A + T) = 2]. The same is true for 

 the "neutral G-forms" [AT-type of DNA, (G + C)/(A + T) = 0.7-0.8]. 



On the other hand, the radical change in properties during the trans- 

 formation of the intestinal bacterium, for example, into the alkali-producing 

 form is accompanied by a very considerable alteration of the DNA composi- 

 tion. Hence, the changes of biological, serological, and other properties are 

 accompanied by quite definite changes of the DNA composition. 



The data on RNA presented in Table XIII show that, in contradistinc- 

 tion, the alterations of the RNA composition in the course of the trans- 

 formation of intestinal bacteria into "saccharolytically inert" forms are not 

 large. It is possible that only a small fraction of the cellular RNA undergoes 

 a change. 



A study of the RNA composition in L-forms produced from P. vulgaris was recently 

 carried out by Mandel and Sensenbrenner. 171 As in the case of the RNA of saccharo- 

 lytically inert forms, no visible differences were found in the RNA composition of 

 the L-forms when compared to the original culture of P. vulgaris. Unfortunately, no 

 data are available in the literature on the DNA composition of L-forms. 



Lynn and Smith studied the DNA and RNA composition in a pleuropneumonia- 



171 P. Mandel and M. Sensenbrenner, Biochim. et Biophys. Acta 29, 642 (1958). 



