32. THE NUCLEIC ACIDS OF MICROORGANISMS 



179 



TABLE X 

 RNA Composition of Fungi* 



* In this table, only the data published since 1955 are included. 



References 



8 D. Elson and E. Chargaff, Biochim. et Biophys. Acta 17, 367 (1955). 



b A. M. Crestfield et al., J. Biol. Chem. 216, 185 (1955). 



c H. Goto and S. Akashi, J. Biochem. (Japan) 44, 681 (1957). 



d A. A. Hakim, J. Biol. Chem. 225, 689 (1957). 



e W. J. Kleinschmidt and J. A. Manthey, Arch. Biochem. and Biophys. 73, 52 (1958). 



' I. S. Kulaev, our laboratory. 



to 22 %. Thus, the molar content of each of the nucleotides varies around 

 some mean value for all the species by no more than 10-12%. In all cases 

 of bacterial RNA studied by us, the relationship was in general G> A~ 

 C > U. The value of the purine to pyrimidine ratio shows an even greater 

 invariability: the amplitude of its variation in the RNA of the bacteria 

 studied ranged from 1.21 to 1.36, i.e., ± 6%. 146 ' 156 Another ratio, namely 

 (G + C)/(A + U), changes somewhat more markedly when passing from 

 species to species, with an amplitude of variation between 1.03 and 1.45; 

 this means that (G + C)/(A + U) = 1.25 ± 0.20, i.e., that all the devia- 

 tions from the value 1.25 keep within ±16 %. 146 This ratio brings out best 

 compositional differences between RNA species. 



However, analytically demonstrable species specificity in RNA composi- 

 tion seems to be restricted to species remote from each other in systematic 

 aspects. It could not be found in closely related species. For example, ac- 

 cording to our data 146 we can definitely speak of the identify (within method- 

 ical errors) of the RNA composition in E. coli, P. morganii, Shigella dysen- 

 leriae, S. typhosa, and S. typhimurium. With a rather high probability we 



166 A. S. Spirin and A. N. Belozersky, Doklady Akad. Nauk S.S.S.R. 113, 650 (1957). 



