GLOSSARY 



Abortive infection: Infection accompanied by loss of the infecting phage particle 

 and often death of the bacterium but not yielding a phage progeny under 

 normally sufficient conditions. Infection is abortive because of unusual 

 conditions prevailing before, at the time of, or shortly after infection. 



Adsorption: Attachment of phage particle to bacterium, irreversible unless 

 otherwise stated. 



Arrhenius constant: The energy of activation of a reaction measured from the 

 dependence of its rate on temperature, explained in elementary texts of 

 physical chemistry. 



Burst: Yield of phage liberated by spontaneous lysis of an infected bacterium. 

 This may be measured directly for isolated bacteria in single burst experi- 

 ments, or as an average burst size in one-step growth experiments. Also 

 the act of liberation. 



Capacity: The ability of a bacterium to support growth of phage when infected. 

 Thus one speaks of the capacity of a bacterial culture varying with the dose 

 of ultraviolet light administered to it before infection. To preserve the 

 usefulness of the term, it should not be used to describe the effects of treat- 

 ment applied after infection. 



Clone: The descendants of a single phage particle, issuing either from a single 

 bacterium or from repeated cycles of infection as in the formation of a 

 plaque. Clones also originate within intrabacterial clones, as demon- 

 strated by the appearance of mutant subclones, or recombinant subclones, 

 in single infected cells. 



Cross-reactivation: Rescue of genetic markers from inviable phage particles in 

 mixed infection with viable particles. 



Doughnuts: Empty heads of phage particles found in lysates of infected bacteria, 

 so called from their characteristic appearance in micrographs of certain 

 types of preparation. 



Eclipse period: Elapsed time between infection or induction and the first appear- 

 ance of infective phage particles in cells, as determined by artificial lysis. 

 The eclipse period of individual cells is variable ; that of the culture may 

 be defined as the time required to produce an average of one phage per bac- 

 terium. The eclipse period is usually ^/o to ^/t of the minimum latent 

 period. 



Efficiency of plating (EOP): Plaque titer of a phage preparation, determined by 

 plating under stated conditions, relative to some other estimate, usually 

 higher, of the concentration of phage particles. 



Exponential killing (or survival) : Inactivation kinetics giving a straight line 



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