The visual pigments of a deep-sea myctophid fish Myctophum nitidulum Garman; an HPLC and spectroscopic description of a non-paired rhodopsin–porphyropsin system |
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| Authors: | E. I. Hasegawa,K. Sawada,&dagger ,K. Abe,&dagger ,K. Watanabe,&dagger ,K. Uchikawa,&dagger ,Y. Okazaki,&Dagger ,M. Toyama,§ R. H. Douglas,&# ¶ |
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| Affiliation: | Research Division, National Salmon Resources Center, 2-2 Nakanoshima, Toyohira-ku, Sapporo, Hokkaido 062-0922, Japan; , Fisheries Information Science Division, National Research Institute of Fisheries Engineering, Hasaki 7620-7, Kamisu, Ibaraki 314-0408, Japan; , Mixed Water Region Fisheries Oceanography Division, Tohoku National Fisheries Research Institute, 3-27-5 Niihamacho, Shiogama, Miyagi 985-0001, Japan; , Department of Biology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan; and Applied Vision Research Centre, The Henry Wellcome Laboratories for Vision Sciences, Department of Optometry and Visual Science, City University, Northampton Sq., London EC1V 0HB, U.K. |
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| Abstract: | Unusually for a deep-sea fish, the retina of the myctophid (lanternfish) Myctophum nitidulum was found to contain two visual pigments, shown by extract spectrophotometry to be maximally sensitive at 468 and 522 nm, respectively, giving this species one of the broadest spectral ranges of all deep-sea fishes. High performance liquid chromatography (HPLC) indicated that the retina contained both A1- and A2-based chromophores. Surprisingly, the maximum absorbance (λmax) values of the two visual pigments were too far apart to form a rhodopsin–porphyropsin 'pigment pair', suggesting they were based on distinct opsins each linked to a different chromophore. This might be an adaptation to the detection of both long-wave bioluminescence and residual shorter-wave surface illumination, and could be related to this animal's tendency to migrate towards surface waters at night. |
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| Keywords: | bioluminescence myctophid porphyropsin rhodopsin spectral sensitivity visual pigment |
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