280 



LIGHT AND LIFE 



in the absence of nucleotides responds to nucleotide addition in a 

 manner analogous to non-incubated extracts. The addition of boiled 

 extract promotes a rapid return to a steady-state value, which depends 

 upon the amount of boiled extract added. Thus, the decay of lu- 

 minescence is brought about as the result of a nucleotide-dependent 

 utilization of some unknown factor required for luminescence. The 

 factor in the boiled extract, which has been found to be dialyzable, 

 will be referred to as RetuUa luciferin by analogy to other biolumines- 

 cence systems. 



Oxygen, as well as nucleotides, is required for luciferin utilization, 

 since a decrease in luminescence activity does not occur by incuba- 

 tion of the complete system under anaerobic conditions. The effect 

 of oxygen on the luminescence of Renilla extracts is illustrated in 

 Fig. 3. Apparently, normal oxygen tension is not sufficient to saturate 

 this system, since flushing with oxygen causes an increase in the 

 steady-state luminescence rate, whereas flushing with air does not. 

 The light is essentially abolished in two minutes by flushing with 

 nitrogen, and the signal is returned by subsequently flushing with 

 oxygen. The somewhat lower steady-state value following the second 

 oxygen flushing is due to some enzyme inactivation as a result of 

 agitation during the flushing process. 



z 



Ul 



H 

 Z 



12 3 4 5 6 7 



TIME (min.) 

 lig. ?>. Kflcct of oxvgcii on Iiiininescciuc. Tlic system was (luslicd alternately 

 wiili owgiii and nilrof^in. as indicated. 



