434 R. M. S. SMELLIE 



Cohen and Weed^^^ have examined the synthesis of 5-hydroxymethyl- 

 cytosine by T6r+ bacteriophage using orotic acid-2-C'^ and serine-3-C'^. 

 These experiments showed that the hydroxymethyl group of the virus 

 hydroxymethylcytosine was almost certainly not derived from the methyl 

 group of the E. coli DNA thymine. Much of the hydroxymethylcytosine 

 of the virus DNA arose from small-molecule precursors in the medium, 

 and it was found that host cytosine but not thymine contributed to the 

 formation of virus hydroxymethylcytosine. 



The catabolism of uracil in the rat has been studied by Rutman et alP^ 

 The direct formation of urea as the most important degradative pathway 

 for uracil in rats has been eliminated. At endogenous levels of uracil metabo- 

 lism negligible quantities of urea are formed, while at higher levels of uracil 

 metabolism some urea is formed. 



A comprehensive review by Schulman^^^ of purine and pyrimidine anabo- 

 lism and catabolism has recently appeared. 



221 L. M. Kozloff, Cold Spring Harbor Symposia Quant. Biol. 18, 209 (1953). 

 "2 S. S. Cohen and L. L. Weed, /. Biol. Chem. 209, 789 (1954). 



223 R. J. Rutman, A. Cantarow, and K. E. Paschkiss, J. Biol. Chem. 210, 321 (1954). 

 22< M. P. Schulman, in "Chemical Pathways of Metabolism" (Greenberg, ed.), Vol. 

 2, p. 223. Academic Press, New York, 1954. 



