Photopigments in photosensory pineal organ

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Photopigments of the direct light-sensitive pineal organ of lamprey, Lampetra japonica, were analyzed by high performance liquid chromatography (HPLC) and by immunohistochemistry.(1) Retinal and 3-dehydro-retinal were identified by HPLC, that means, the presence of the mixture of vitamin-A1-based pigment and vitamin-A2-based pigment was confirmed.(2) The ratio of all-trans isomer to 11-cis isomer was higher than that of retina.(3) Photopigment sensitive to short wavelength light was confirmed by the finding that the ratio of all-trans isomer to 11-cis isomer was reversed when the sample was irradiated by the short wavelength light after the orange light irradiation. The finding coincides the high sensitivity of pineal orgen to short wavelength light demonstrated electrophysiologically.(4) Spectral sensitivity was measured intracellularly in the pineal photoreceptor cells of adult and larval lamprey. The spectral sensitivity curve of larval pineal has a peak at 505 nm and that of adult was 20 nm shifted toward longer wavelength. This suggests the conversion of the visual pigment during the metamorphosis.(5) Opsin-positive photoreceptor cells were observed immunohistochemically. The reactivity was restricted in the outer segment of the photoreceptor.(6) Visinin-positive photoreceptor cells were observed in the periphery of the pineal. Gradation of visinin reactivity suggests the different types of photoreceptors in the pineal.(4) photoreceptor cells were also confirmed inM parapineal organ immunohistochemically.