NUCLEIC ACID TRANSFER FROM PARENTAL 

 TO PROGENY BACTERIOPHAGE 



by 



J. D. WATSON*. ** AND O. MAAL0E 



Institute for Cytophysiology and State Serum Institute, Copenhagen {Denmark) 



INTRODUCTION 



In recent years several investigators have used isotopic markers to determine the 

 transfer of P or N atoms from parental to progeny virus particles. Putnam and KozloffI 

 using the bacteriophage T6 labelled with ^^V, found that 20-40% of the label appeared 

 in material identified as progeny phage by differential centrifugation. Leslie et al.^ 

 found similar, or lower, values with ^^P-labelled T2 bacteriophage. Kozloff^ extended 

 his original observations by studying P and N transfer from normal as well as radiation 

 damaged phage particles. All these experiments show incomplete transfer varying 

 greatly from one experiment to the other. 



To determine the true transfer values, two technical problems must be solved: 

 (i) adsorption of the labelled phage must be complete within about 2 minutes because 

 later adsorbing particles are broken down before entering the cells (Leslie et al.^), 

 (2) means must be found to prevent progeny particles from adsorbing onto bacterial 

 debris or unlysed cells. Failure to control either of these processes will result in under- 

 estimation of the transfer values. 



In our first experiments (Maal0e and Watson*), although the second factor was 

 well controlled, the first was not, and our ^^F transfer values of about 30% were, there- 

 fore, hke those of Putnam and KozloffI. Leslie et al.^, and Kozloff^, too low. In 

 this paper, we present experiments in which both factors are controlled, and which 

 indicate that T2 and T4 phages transfer about 50%, T3 phages about 40% of their 

 phosphorus to the progeny. Identical values are found when, instead of ^^p, i*C-labelled 

 adenine is used to label the parental phage. The ^2? experiments show that the trans- 

 ferred material goes predominantly to the early formed phages, and that the transfer 

 values of about 50% are maximum values. Our finding that the early completed phages 

 receive most of the parental material confirms similar observations by Doermann 

 (personal communication) and Weed and Cohen^ (unpubhshed) . 



In agreement with Kozloff^, we have also demonstrated that considerable amounts 

 of 32? may be transferred from labelled particles which do not participate in repro- 

 duction, either because of radiation damage or because they are excluded by another 

 phage. These "abnormal" cases show that infecting particles may be broken down 



* Merck Fellow in the Natural Sciences of the National Research Council at the Institute for 

 Cytophysiology, Copenhagen. 



** Present address; Cavendish Laboratory, Cambridge, England. 



References p. 442. 



Reprinted by permission of the authors and Elsevier Publishing Co. 

 from BiocmMiCA et Biophysica Acta, 10, 432-442 (1953). 



105 



