Pyrimidine Moieties in Animals, Plants, and Bacteria 111 



triphosphate, but DNA exercised a directing role in the enzymatic 

 synthesis of RNA. DNA from several sources, having widely 

 different base compositions, could serve as primers for the synthesis 

 of RNA by KNA polymerase, but the newly synthesized RNA 

 had a composition which reflected the composition of the DNA 

 primer which was einployed. With the purified enzyme, RNA 

 synthesis only took place if DNA was present. 



Single stranded DNA from phage 0X174 could serve as primer 

 in which case the RNA had a composition complementary to the 

 DNA of 0X174 (7). If double stranded 0X174 DNA was enzy- 

 matically prepared with DNA polymerase and the double stranded 

 0X174 DNA was then used as a primer for the synthesis of RNA 

 by RNA polymerase, the RNA product had a composition similar 

 to double stranded 0X174 DNA. In addition, RNx\ synthesis was 

 primed by heat denatured DNA (23, 80). These results suggested 

 that each of the complementary DNA strands could serve as tem- 

 plates for the synthesis of Messenger-RNA. However, it is not yet 

 definite that this happens in vivo. Possibly, only one of the DNA 

 strands serves to specify the sequence of messenger-RNA and the 

 second strand constitutes "nonsense" information. 



Not only is the composition of the newly synthesized RNA 

 dependent on the composition of the DNA primer, but the se- 

 quence of the ribonucleotides in the new RNA is determined by 

 the sequence of deoxyribonucleotides in the DNA. This has been 

 demonstrated in two ways. First, nearest neighbor sequence studies 

 have been carried out by Furth, Hurwitz, and Goldman (24) and 

 by Weiss and Nakamoto (81). Second, it has been demonstrated 

 that enzymatically synthesized RNA formed with a T-2 phage 

 DNA primer can be heated with the T-2 DNA and slowly cooled 

 so as to permit hybrid formation by renaturation (25). The hybrid 

 has been demonstrated by density gradient centrifugation experi- 

 ments. Hybrid formation occurs between C-RNA specific to T-2 

 phage and T-2 phage DNA, but not between G-RNA of T-2 

 phage and E. coli DNA or sea urchin DNA. 



The existence of T-2 specific RNA, which was initially inferred 

 from the isotope experiments of Volkin and Astrachan, was estab- 

 lished by Nomura, Hall, and Spiegelman (49). Newly synthesized 

 RNA was separated from the bulk of cellular RNA using both 



