Pyrimidine Moieties in Animals, Plants, and Bacteria 107 



molar per cent (G+C) varies from 50 per cent (G+C) for Proteus 

 vulgaris to 59 per cent (G + C) for Alycobacterium tuberculosis. The 

 values for most bacterial species are close to 55 per cent (G+C). 

 The DNA nucleotide values for Proteus vulgaris and Mycobacterium 

 tuberculosis are 39 per cent and 67 per cent (G + C), respectively, 

 (Table II); and, as mentioned previously, the DNA values for 

 all species range from 32 per cent to 73 per cent (G + C). 



The RNA molar nucleotide composition of algae varies from 

 52 to 56 per cent (G + C) (Table XI), whereas the corresponding 

 DNA values manifest a much broader variation, that is, from 37 

 to 64 mole per cent (G + C) (Table III). The RNA molar nucleo- 

 tide values of higher plants vary over a 4 per cent (G+C) range 

 (52.9 to 56.9) and the values from fungi vary over a 6 molar per 

 cent (G + C) range (50 to 56). On the other hand, the DNA 

 values for higher plants range from 35 molar per cent (G + C) to 

 48 molar per cent (G+C) (Table III), and the DNA values for 

 fungi vary from 36 to 54 mole per cent (G + C) (Table IV). The 

 molar per cent (G + C) is much greater in protozoan RNA than 

 in protozoan DNA (Tables IV, XI). The nucleotide composition 

 of the RNA of higher animals is extremely high, over 60 per cent 

 (G+C); while the DNA of the animal species contains about 40 

 to 44 per cent (G+C) (Tables VI, XI, XII). No significant 

 differences have so far been detected between the RNA base 

 composition of different tissues of the same animals or between 

 normal tissues and tumors (34, 39, 44). 



Virus RNA 



A third kind of RNA is that found in plant, animal, and bacterial 

 viruses (Table XIII), RNA viruses are capable of replicating 

 within cells in the absence of new DNA synthesis (55, 64) but the 

 mechanisms by which the RNA templates of the viruses are 

 replicated are not known. Conceivably, an RNA strand might 

 serve as a template for the replication of a complementary strand. 

 However, there is no evidence that RNA duplexes exist or that 

 strands of complementary base composition occur in RNA viral 

 populations. The molecular weight of the RNA of viruses is 

 approximately 2 million (9, 22). It is rather interesting that all 

 but one of the thirteen plant and animal RNA viruses contain 



