THE EFFECT OF LIGHT ON THE OCELLAR PIGMENT OF SPIROCODON, AN ANTHOMEDUSA

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Abstract
Abstract— The ocellar pigment of Spirocodon saltatrix was extracted with 2% mildly alkaline cetyltrimethylammonium bromide (CTAB) and 90% methanol acidified with HCl. In the case of CTAB‐extracted pigment, maximum changes in optical density upon illumination occurred in mildly alkaline media under aerobic conditions and in neutral media under anaerobic conditions. The density spectrum of the sample illuminated under anaerobic conditions closely resembled that of the reduced form of the pigment illuminated in the presence of air. When reduced in darkness, the pigment became photostable and its density spectrum differed from that of the pigment reduced after illumination. On aeration of the pigment solution illuminated under anaerobic conditions, its density spectrum in the visible range became similar to that of the pigment illuminated in the presence of air. A trace of air dissolved in experimental media caused auto‐oxidation of the reduced form, during the process of which a definite isosbestic point was observed at 480 mμ. Under anaerobic conditions, short period of illumination produced changes in spectral absorbance only in the visible range. Changes in the u.v. range required longer exposures. The pigment extracted with acidified methanol was readily auto‐oxidizable and it was the reduced form which showed photosensitivity, though the degree of sensitivity was extremely low. The density spectrum of illuminated pigment resembled that of the oxidized form. From these experiments, a tentative scheme involving an electron transfer system has been suggested for the chain of photic reaction of the anthomedusan ocellar pigment.

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