162 BACTERIOPHAGES 



ribonuclease. About 90 per cent of both the phosphorus and 

 sulfur was specifically adsorbable to sensitive bacteria and 

 precipitable by anti-T2 serum, suggesting that the phage was 

 relatively free of extraneous protein and nucleic acid. The 

 labeled phage was subjected to osmotic shock, which separates 

 the phage nucleic acid from the phage membrane or ghost 

 (Chapter V). In the resulting shocked phage neither the 

 phosphorus nor the sulfur was acid-soluble. However, treat- 

 ment with deoxyribonuclease made 80 per cent of the phos- 

 phorus acid-soluble, the sulfur remaining insoluble. About 

 90 per cent of the sulfur was still adsorbable to sensitive bac- 

 teria but only 2 per cent of the phosphorus could be adsorbed. 

 About 97 per cent of the sulfur was precipitable by anti-T2 

 serum but only 5 per cent of the phosphorus. These results 

 confirm the previous observations of Anderson and Herriott 

 that osmotic shock permits the separation of phage T2 into 

 a protein membrane and soluble DNA. They indicate fur- 

 ther that almost all of the phage sulfur and almost none of the 

 phage phosphorus is in the membrane which adsorbs to the 

 host cell and precipitates with antiserum. Conversely, most 

 of the phosphorus and little of the sulfur is in the DNA which is 

 liberated from the membrane and thereby made susceptible 

 to attack by deoxyribonuclease. 



Electron micrographs of infected bacteria had demonstrated 

 that phage T2 adsorbs to its host cell by the tip of its tail (Chap- 

 ter IV). This suggested the possibility that the adsorbed 

 phage might be broken off from the bacterial surface by the 

 strong shearing forces in a Waring Blendor. In fact, Anderson 

 (1949) had found that phage does not adsorb to the host cell 

 while the adsorption mixture is agitated in the Blendor. Her- 

 shey and Chase (1952) performed the appropriate experiments 

 using isotope-labeled phage. The phage was adsorbed to the 

 host cell at low multiplicity of infection and unadsorbed phage 

 was eliminated by centrifugalion. The infected bacteria 

 were agitated in the Blendor for various times and the cHs- 

 tributions of sulfur and phosphorus between bacteria and 



