352 



GEORGE BOSWORTH BROWN AND PAUL M. ROLL 



ADENINE 



V 



INOSINE 



\adenosine 



ADENYLIC 

 ACID. 2', 3' or 5' 



\ 



2, 6-DIAMINO- 

 PURINE 



2, 6-OIAMINOPURINE 

 RIBOSIDE 



\ 



GUANINE 



/CUANOSINE 

 CROTONOSIDE 



GUANYLIC 

 ACIO(S), or 3' 



NUCLEIC 

 ACIDS 

 PNA 



Adenine 



Guoncne 



Fig. la. Purines and purine derivatives which can function as polynucleotide 

 precursors in the rat. 



CYTOSINE 



OROTIC ACID- 



CYTIDINE 



\ 



CYTIOYLIC 

 ACID (S) 



\ 



/ 

 / 

 URACIL 



/ 



T 



NUCLEIC 

 ACIDS 

 PNA 



Cylosine 



URIOYLIC 

 ACID(S) 



Fig. lb. Pj'rimidines and pyrimidine derivatives which can function as poly- 

 nucleotide precursors in the rat. 



The heavy lines indicate the most extensive incorporations, lighter lines moderate 

 incorporation, and broken lines mere trace incorporation. The lines are intended to 

 indicate only the overall conversions observed and no sequence of reactions is to be 

 implied. 



The dotted line indicates that appreciable transformations of those derivatives 

 into deoxyribopolynucleotide components have been observed. 



Fig. 1 depicts the array of precursors which have been shown to be ca- 

 pable of serving as precursors of the polynucleotides in the laboratory rat. 

 In that outline the only distinctions which have been made are between 

 those compounds which are very extensively incorporated, those which are 

 definitely specific precursors but are incorporated to a more moderate 

 extent, and those with which only a very small incorporation has been 

 observed. In all cases except the one study with cytidine^* and one with 



