Istituto di Biofisica     
Losi A., Vecli A., Viappiani C., Angelini N., Ghetti F., Lenci F. Photoacoustic spectroscopy of non radiative transitions in photoreceptor pigments from Blepharisma japonicum. In: Médicine biologie environment, vol. 22 (1) pp. 165 - 173. INEC, 1994.
The distribution ofthe photoexcitation energy in blepharismin, the receptor pigment of the photoresponsive protozoan Blepharisma japonicum, has been investigated by optical absorption and emission spectroscopy and by time-resolved photoacoustic measurements; the resulting energy balance may help in clarifying the molecular mechanisms of the primary photosensory processes (phototransduction). According to a model which takes into account the intersystem crossing to the triplet state ofthe pigment and the subsequent energy transfer to molecular oxygen, for red blepharismin a sensitizing action was detected with efficiency lower than one. Comparative measurements, performed on the parent compound hypericin, gave correct results for the sensitizing efficiency of the dye. Preliminary measurements performed in water-ethanol mixtures evidenced a fluorescence quenching of red blepharismin, as well as hypericin, upon increasing the water to ethanol molar ratio.
Subject Photoreception
Blepharisma japonicum

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