202 ROBERT L. SINSHEIMER 



trait "glucose content" in these crosses segregates from the host range 

 marker, but not symmetrically, as many more of the recombinant phages 

 are found with the glucose content of T2 and the host range of T6 than 

 vice versa. 



While the extent of degradation of T2 DNA by pancreatic deoxyribo- 

 nuclease is the same as is found with DNA from other sources (approxi- 

 mately 25 % of the diester linkages are split) the presence of the glycosyl 

 residues appears to inhibit the action of venom diesterase upon the deoxy- 

 ribonuclease digest. Thus, it has not been possible to obtain quantitative 

 reduction of DNA from the T-even phage to mononucleotides. 76 Using 

 conditions under which calf thymus DNA would be completely degraded 

 to mononucleotides 78 it is possible with T2 DNA to obtain about 70% of 

 the deoxyguanylic, deoxyadenylic, and thymidylic acids as mononucleotides, 

 54% of the 5-hydroxymethyldeoxycytidylic acid (dHMP) and only 24% 

 of glucosylated 5-hydroxymethyldeoxycytidylic acid. 73 Jesaitis 79 similarly 

 obtained from T6r + DNA, 60% of the deoxyguanylic, deoxyadenylic, and 

 thymidylic acids as mononucleotides, about 40 % of the 5-hydroxymethyl- 

 deoxycytidylic acid and only 20 % of the diglucosylated 5-hydroxymethyl- 

 deoxycytidylic acid. 



There has been a report of a correlation of glucose content with the r 

 character of several phages 80 but this was not confirmed with other strains. 73 



Attempts at fractionation of T6r+ DNA from a nucleohistone gel 81 yielded 

 fractions with significant variations of nucleotide composition. While in all 

 cases the fractions preserved the adenine-thymine and guanine-hydroxy- 

 methylcytosine equalities, the ratio of adenine to guanine varied from 1.60 

 to 1.98. 



Bendich et al. have obtained numerous fractions from T6r and T6r + 

 phage DNA by column chromatography 82 on Ecteola but no data have been 

 reported as to the nucleotide composition of these fractions. 



Brown and Martin obtained two fractions, A and B, on a modified his- 

 tone column which differed slightly in nucleotide composition 58 and which 

 differed notably in the extent of glucose substitution upon the 5-hydroxy- 

 methylcytosine. 60 In fractions A and B, 65% and 100% of the HMC resi- 



76 It has recently been reported that I. R. Lehman has obtained an enzyme fraction 

 from E. coli that will accomplish a quantitative degradation of T2 DNA to mono- 

 nucleotides." 



77 A. Romberg, S. B. Zimmerman, S. R. Romberg, and J. Josse, Proc. Natl. Acad. 

 Sci. U. S. 45, 772 (1959). 



78 R. L. Sinsheimer and J. F. Roerner, J. Biol. Chem. 198, 293 (1952). 

 " M. A. Jesaitis, J. Exptl. Med. 106, 233 (1957). 



80 S. S. Cohen, Science 123, 653 (1956). 



81 C. F. Crampton, R. Lipshitz, and E. Chargaff, J. Biol. Chem. 211, 125 (1954). 



82 A. Bendich, H..B. Pahl, and S. M. Beiser, Cold Spring Harbor Symposia Quant. 

 Biol. 21, 31 (1956). 



