DIFFERENTIAL DISTRIBUTION ANALYSIS 



141 



acids that belong to the AT type. It was of interest to see 

 whether the same considerations could be applied to a nucleic 

 acid of the GC type, i.e., one in which guanine and cytosine 

 preponderated. We first discovered this type in tubercle bacilli^^; 

 but it has since that time been found in many micro-organ- 

 isms^'^^. The distribution analysis of the deoxyribonucleic acid 

 of an avirulent variant (BCG) of bovine tubercle bacilli is shown 

 in Table 31. In the nucleic acids of the AT type, as was shown 

 before, the quantity of thymidine 3',5'-diphosphate released 



SOLITARY PY NUCLEOTIDES 

 BASES, MOLE % IN DNA 



TOTAL RGDNA 

 RGDNA-0.60 

 RGDNA- 0.65 

 RGDNA- 0.70 

 RGDNA- 0.75 

 RGDNA- 0.80 

 RGDNA- 0.90 

 RGDNA- 1.70 



IN RYE GERM DNA & FRACTIONS 



DIPHOSPHATES, % OF BASES 

 5 10 15 20 25 



0,T D , C ■ , M 



Fig. 12. Pyrimidine distribution analysis of the total deoxyribonucleic acid 

 of rye germ and its fractions. The first column indicates the NaCl molarity 

 at which dissociation of the fraction from its histone salt occurred. The 

 second column summarizes the composition of the specimens in terms of 

 the molar concentrations (per 100 gram-atoms of nucleic acid P) of thy- 

 mine (T), cytosine (C), and 5-methylcytosine (M). The histogram shows the 

 frequency of the solitary nucleotides, isolated as the nucleoside 3',5'- 

 diphosphates, relative to the total concentration of the constituent in the 

 nucleic acid. Based on previously published data^^. 



References p. 159 



