VmUS-INDUCED ACQUISITION OF METABOLIC FUNCTION 33 



duces its formation despite the prevention of DNA synthesis. This syn- 

 thesis of internal protein is not blocked by proflavine but is prevented 

 by chloramphenicol. It appears significant that if this inhibitor is added 

 at various times early in infection, a correlation appears to exist betw'een 

 DNA synthesized and internal protein formed prior to addition of the 

 agent. When the inhibitor is added ten minutes after infection, the rate 

 of DNA synthesis remains high until the phage equivalents of DNA 

 approach that of internal protein. At this point, the rate of DNA syn- 

 thesis falls ( Murakami et al., 1959). 



The formation of the polypeptide, but not the polyamines, is also 

 blocked by chloramphenicol (Hershey, 1957). The recent studies of Kel- 

 lenberger et al. ( 1959 ) , showing the late formation of a chlorampheni- 

 col-sensitive principle essential to the condensation of elements of the 

 DNA pool, raises the problem of the possible relation of this poly- 

 peptide to the condensing principle and its mechanism of action. 



Following the condensation of phage DNA between nine and 

 eleven minutes after infection, it appears that centers are produced on 

 which may be constructed the numerous structures ( at least seven ) of 

 the phage head and tail. Of these, at least two possess enzymatic ac- 

 tivity essential for the penetration of phage DNA into the bacteria. 

 These are lysozyme (Koch and Dreyer, 1958) and an ATPase (Dukes 

 and Kozloff, 1959). It has not been reported when these enzymes are 

 elaborated or whether the appearance of the activity and the phage 

 structure take place simultaneously. 



Concluding remarks 



The phenomena of the appearance of new enzymes described 

 above will certainly not be confined to the T phages. The development 

 of a polysaccharidase in Klebsiella infected by a phage was described 

 some years ago (Park, 1956; Adams and Park, 1956). In this interesting 

 case, the polysaccharidase, which hydrolyzed the bacterial capsule, 

 was found both in a soluble form in the lysate and associated with the 

 phage. The enzyme thus appears to facilitate attachment of the phage 

 to the bacterium. 



Several similar phenomena have been described in animal virus 

 systems. The appearance of neuraminidase in myxovirus-infected cells 

 is well known, although inadequately explored. More recently, Rogers 

 ( 1959 ) has described the appearance of arginase in rabbit epithefium 

 infected by rabbit papilloma virus. Thus the acquisition and/or increase 

 of metaboHc function as a result of the addition of the viral genome to 

 the infected cell will have the widest significance in explaining not only 

 parasitic mechanisms but also the possible mode of action of tumor 

 viruses as well. 



