Inhibition and Activation 



of Intracellular Luminescence* 



Frank H. Johnson 

 Department of Biolog> ', Princeton University, Princeton, New Jersey 



For the purposes of this discussion we may define intracellular lumi- 

 nescence as visible light emission resulting from metabolic processes 

 within intact, living cells, such as bacteria, independently of nervous 

 or other physiological mechanisms that regulate the luminescence of 

 tissues and organs in complex organisms, such as the firefly. An under- 

 standing of how various factors operate to inhibit or to activate intra- 

 cellular luminescence is obviously an important aspect of the total 

 problem of bioluminescence in particular. Of no less importance are 

 the contributions that advances in the understanding of this particular 

 process have made, or may make, toward the understanding of the 

 general problem of inhibition and activation in various other biologi- 

 cal processes, both relatively simple and highly complicated. It seems 

 appropriate, therefore, to consider both these aspects, and in the dis- 

 cussions which follow, certain principles or concepts, which were either 

 first recognized clearly, or whose establishment has been especially 

 aided through studies of bioluminescence, are hsted, together with a 

 few examples indicating the applicability of these concepts to processes 

 other than luminescence. 



Intracellular luminescence is limited first of all, of course, by genet- 

 ically determined potentialities: the catalytic machinery as well as 

 other factors essential for fight emission must be present. Among lumi- 

 nous bacteria, mutant strains that emit no visible light, or that exhibit 



* This paper has been aided by a contract between the Office of Naval 

 Research, Department of the Navy, and Princeton University. 



265 



