Rhodopsin in the Dark Hot Sea: Molecular Analysis of Rhodopsin in a Snailfish, Careproctus rhodomelas, Living near the Deep-Sea Hydrothermal Vent.
Visual systems in deep-sea fishes have been previously studied from a photobiological aspect; however, those of deep-sea fish inhabiting the hydrothermal vents are far less understood due to sampling difficulties. In this study, we analyzed the visual pigment of a deep-sea snailfish, Careproctus rhodomelas, discovered and collected only near the hydrothermal vents of oceans around Japan. Proteins were solubilized from the C. rhodomelas eyeball and subjected to spectroscopic analysis, which revealed the presence of a pigment characterized by an absorption maximum (λmax) at 480 nm. Immunoblot analysis of the ocular protein showed a rhodopsin-like immunoreactivity. We also isolated a retinal cDNA encoding the entire coding sequence of putative C. rhodomelas rhodopsin (CrRh). HEK293EBNA cells were transfected with the CrRh cDNA and the proteins extracted from the cells were subjected to spectroscopic analysis. The recombinant CrRh showed the absorption maximum at 480 nm in the presence of 11-cis retinal. Comparison of the results from the eyeball extract and the recombinant CrRh strongly suggests that CrRh has an A1-based 11-cis-retinal chromophore and works as a photoreceptor in the C. rhodomelas retina, and hence that C. rhodomelas responds to dim blue light much the same as other deep-sea fishes. Because hydrothermal vent is a huge supply of viable food, C. rhodomelas likely do not need to participate diel vertical migration and may recognize the bioluminescence produced by aquatic animals living near the hydrothermal vents.
Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), Tokyo, Japan.
Rie
R
Sakata
Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), Tokyo, Japan.
Ryo
R
Kabutomori
Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), Tokyo, Japan.
Keiko
K
Okano
Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), Tokyo, Japan.
Hiromasa
H
Mitsui
Department of Chemistry, Biology, and Marine Science, Faculty of Science, University of the Ryukyus, Okinawa, Japan.
Akihiro
A
Takemura
Marine Technology Development Department, Marine Technology and Engineering Center, Japan Agency for Marine Earth Science and Technology (JAMSTEC), Yokosuka, Japan.
Tetsuya
T
Miwa
Environmental Impact Assessment Research Group, Research and Development Centre for Submarine Resources, Japan Agency for Marine Earth Science and Technology (JAMSTEC), Yokosuka, Japan.
Hiroyuki
H
Yamamoto
Department of Electrical Engineering and Bioscience, Graduate School of Advanced Science and Engineering, Waseda University (TWIns), Tokyo, Japan.
Toshiyuki
T
Okano
D000818:Animals; D018076:DNA, Complementary / Q000378:metabolism; D005399:Fishes / Q000378:metabolism; D060086:Hydrothermal Vents; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D012243:Rhodopsin / Q000032:analysis*
D018076:DNA, Complementary; D012243:Rhodopsin