Fluorescence and luminescence of isolated photophores of Porichthys.

1. Isolated photophores of Porichthys exposed to u.v. light (365 nm) exhibit a green fluorescence localized in the photocytes and a bluish fluorescence originating from the lens-like body. 2. The luminescence of photophores evoked by epinephrine, nor-epinephrine or potassium cyanide decreases with the intensity of the green fluorescence of the photogenic tissue; the bluish fluorescence of the lens-like body does not change significantly. 3. The total amount of light emitted is a linear function of the decrease of the greenish fluorescence intensity. The slope of the regression line is maximal in response to epinephrine or nor-epinephrine 5.10(-4)M and potassium cyanide 10(-3)M. It decreases significantly for higher concentrations. 4. The decrease of fluorescence observed during the light emission is tentatively explained by oxidation of a luciferin present in a fluorescent form in a fresh photophore.