Bioluminescence
The bioluminescence of A. fischeri is caused by transcription of the Lux operon, induced by population-dependent quorum sensing. The luminescence is seen only when population density reaches a certain level. The luminescence appears to follow a circadian rhythm. That is, it is brighter during the nighttime than during the daytime. Bioluminescence levels have also been shown to be proportionally related to both protection against ultraviolet radiation damage to genes and the pathogenicity of bioluminescent A. fischeri.
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