^38 J- D. WATSON, O. MAAL0E VOL. 10 {1953) 



experiment was 350, or 2 or 3 times greater than in the experiment with T4r. Despite 

 this increase in phage yield, the transfer was again about 50%, showing that the late 

 formed particles received very little, if any, of the parental phosphorus. 



The experiment reported in Table VI shows directly that the transferred ^2? goes 

 predominantly to the early formed particles. In this experiment, bacteria infected with 

 labelled T2r+-phage were lysed prematurely by addition of M/iooo KCN and a large 

 number of ultraviolet inactivated phage, as previously described*. The excess of added 

 phage served as carrier material during centrifugation, and insvued that the labelled 

 progeny particles were effectively isolated even when the yield was low. Several identical 

 experiments were carried out, all showing the same trend. Thus the material which an 

 infecting particle transfers to the progeny usually goes to one or more of the early 

 formed particles, while the later formed ones virtually never receive any of it. We 

 therefore conclude that our transfer values of about 50% are true maximum values. 

 Table VI also shows that bacteria lysed before the appearance of the first progeny 

 particles contain insignificant amounts of radioactivity sedimentable at high speed. 

 This is additional evidence that our results are not affected by spurious measurements 

 of non-infective but still sedimentable parental particles released upon lysis. 



TABLE VI 



DISTRIBUTION OF PARENTAL 32p AMONG PROGENY PARTICLES FROM PREMATURELY LYSED BACTERIA 



Concentrated B/i were infected with an average of 5 ^^P-iabelled T2r+ particles per bacterium. 

 Two minutes after infection the culture was chilled and centrifuged at 5000 g for 4 minutes to remove 

 unadsorbed radioactivity. The pellet was resuspended in broth at 37° C at a bacterial concentration 

 of 108 cells/ml. The progress of phage growth was retarded about 8 minutes by the coolmg and cen- 

 trifugation. Ten minutes after infection ultraviolet (UV) inactivated T2r+ at the average multiplicity 

 of 5 particles was added to inhibit lysis. Samples of the infected bacteria were then broken open 

 at various times by the addition of Mjiooo KCN and approximately 2000 UV inactivated T2r+ 

 particles per cell. Readsorption of the progeny particles was prevented by saturation of the bacterial 

 surface with the UV treated phage (Maaloe and Watson*). 



Isotope transfer in the absence of genetic transfer 



The "second generation experiment" (Maal0E and Watson*) referred to earher 

 in this paper permits the conclusion that the transmitted phosphorus is distributed in 

 the progeny particles in the same uniform way as in the parental particles. It leaves 

 open the question whether transfer occurs via large blocks carrying biological specificity 

 or via highly degraded material. In this study we have tried to answer a complementary 

 question: Does isotope transfer occur under conditions where no genetic transfer is 

 possible? i.e., can material from an infecting particle be broken down to genetically 

 unspecific structures which are then incorporated into new phage particles? 

 References p. 442. 



Ill 



