CHAPTER VI 



EFFECTS OF RADIATIONS ON PHAGE 

 PARTICLES 



The discussion of the action of various physical and chemical 

 agents on the viability of bacteriophages will now be continued 

 by a consideration of the effects produced in phage particles 

 which have been exposed to various sorts of radiations. The 

 irradiation of bacteriophages has been a very useful tool in the 

 elucidation of their structure and physiology, and it may be said 

 that with bacteriophages radiobiological methods have found one 

 of their most profitable applications. Diverse types of bacterio- 

 phages have at some time or other been subjected to radiations of 

 almost all parts of the electromagnetic spectrum, ranging in 

 wavelength from the infrared (3,000,000 to 7,600 A) through the 

 visible (7,600 to 4,000 A) and ultraviolet (4,000 to 130 A) to 

 the X-ray regions (100 to 0.1 A), and extending even to the 

 most highly energetic radiations of extremely short wavelength 

 emitted by radioactive substances and those produced in the ac- 

 celerators of atomic physics. The body of literature concerned 

 with this subject is already so large that not all of the results can 

 be discussed here. The reader may find further information in a 

 number of specialized reviews (Lea, 1946; Bowen, 1953; 

 Luria, 1955; Pollard, 1954; Kleczkowski, 1957; Stent, 1958). 



1. Visible Light 



Wahl and Guelin (1942) observed that the small phage SI 3 

 is particularly sensitive to inactivation by light, being killed by 

 radiations from the visible part of the spectrum at a much 

 greater rate than the large phage CI 6. Wahl (1946b) found by 

 use of appropriate filters that the wavelength of the active 



63 



