• Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.8-15
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• 2007

Rhodopsin, a dim-light receptor, is a model system for the study of G protein-coupled receptors that transduce extracellular signals into cells. To study the molecular mechanisms of visual systems in fish, the rod opsin gene of olive flounder Paralichthys olivaceus was characterized. The full-length P. olivaceus opsin gene was obtained by PCR amplification of genomic DNA, as well as cDNA synthesis. A comparison of clones obtained from both methods indicated that the olive flounder rod opsin gene lacks introns. Sequence analysis of the opsin gene indicated that it contains a 1,056-bp open reading frame encoding 352 amino acids. The deduced amino acid sequence contains features of typical rod opsins, such as sites for Schiff's base formation (K296) and its counterion (E113), disulfide formation (C110 and C187), and palmitoylation (C322 and C323). An opsin sequence alignment showed the highest similarity between P. olivaceus and Solea solea (95.1%), followed by Hippoglossus hippoglossus (94.5%). An opsin phylogenetic tree revealed a close relationship between olive flounder and teleost rod opsins.

• Journal of Photoscience
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• v.9 no.2
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• pp.269-271
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• 2002

To investigate the visual and extra-ocular photoreception, we cloned the opsin genes in ayu (Plecoglossus allivelis). Amplified fragments encoding exon-4 (-5) of opsin cDNAs were cloned from the retina and brains of ayu, and sequenced. One clone was identified as rod (AYU-Rh), two as green cone (AYU-GI, -G2), one as red cone (A YU-R), two as ultraviolet cone (AYU-UVl, UV2), one as VA (AYU-VA), and one as extra-ocular rod (AYU-ExoRh) opsins. 335 amino acids sequence deduced from the full-length cDNA of AYU-Rh showed high identity with that of other fish. Southern blotting analysis indicated that ayu possess two 'rhodopsin' genes, one is visual rhodopsin and the other is non-visual extra-ocular rhodopsin. In situ hybridization showed that the mRNA of AYU-Rh was localized only in rod cells in the retina. On the other hands, AYU-ExoRh was expressed only in the pineal. We cloned two isoforms (AYU-VAM and -VAL) of VA opsin from ayu. The deduced amino acid sequences of these variants were identical to each other within the first 342 residues, but they showed divergence in the C-terminal sequence. AYU- VAL corresponded to the long isoform found in other fish, and AYU-VAM was identified as a new type of VA opsin variant. Pal-VAM is a new probably functional non-visual photoreceptive molecule in fish.

• Development and Reproduction
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• v.23 no.2
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• pp.171-181
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• 2019

To produce healthy and stable seed production, we need to obtain information and understand vision that affects behavior of red spotted grouper. We examined their expression and retinal development during the juvenile development. Short-wavelength sensitive opsin (SWS2), a cone photoreceptor, began to be expressed from lens and ear vesicle formation stage and its expression increased until 10 days after hatching (dah). In case of middle-wavelength sensitive opsin (MWS), its expression was detected at 3 dah and reached the highest level at 21 dah. The expression of long-wavelength sensitive opsin (LWS) was first observed from 3 dah and their expression decreased thereafter. Rhodopsin, a rod photoreceptor, was found to be expressed from 2 dah and its expression reached the highest level at 50 dah. The outer nuclear layer (ONL), inner nuclear layer (INL) and ganglion cell layer began to differentiate at 2 dah, while choroid first appeared at 4 dah so that the eyes became black. These results indicate that the development of retina mostly completes around 4 dah. It seems that the development of the retina and the expression of the opsin genes are closely related to the behavior such as hunting prey, considering that the timing of the completion of the development of the retina, the timing of gene expression, and the timing of completion of yolk absorption are similar.

• Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.265-275
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• 2009

G Protein-coupled receptors (GPCRs) mediating wide ranges of physiological responses is one of the most attractive targets for drug development. Rhodopsin, a dim-light photoreceptor, has been extensively used as a model system for structural and functional study of GPCRs. Fish have rhodopsin finely-tuned to their habitats where the intensity and the wavelength of lights are changed depending on its water-depth. To study the detailed molecular characteristics of GPCR architecture and to understand the fishery light-sensing system, genes encoding rod opsins were isolated from fishes living under different photic environments. Full-length rod opsin genes were obtained by combination of PCR amplification and DNA walking strategy of genomic DNA isolated from olive flounder, P. olivaceus, Japanese eel, A. japonica, and Common carp C. carpio. Deduced amino acid sequences showed a typical feature of rod opsins including the sites for Schiffs base formation (Lys296) and its counter ion (Glu113), disulfide formation (Cys110 and Cys187), and palmitoylation (Cys322 and Cys323) although Cys322 is replaced by Phe in Japanese eel. Comparison of opsins by amino acid sequence alignment indicated the closest similarity between P. olivaceus and H. hippoglossus (94%), A. japonica and A. anguilla (98%), and C. carpio and C. auratus (95%), respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.1
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• pp.69-76
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• 2016

Purpose: The study was conducted to determine that photoreceptors of mouse having pigment in RPE(retinal pigment epithelium) can be damaged by blue-light and apoptosis of specific cells among photoreceptors are induced by blue-light, and to assist the investigation of AMD(Age-related macular degeneration) mechanisms and development of AMD drugs. Methods: C57Black mice were injured by irradiating $2800{\pm}10lux$ of 463 nm LED for 6 hours after 24 hours dark adaptation and eyes were enucleated 1, 3, 7 days. Damage of retina induced by blue-light was determined by western blotting GFAP(Glial fibrillary acidic protein) expression. In the light-injured retina, cell death of photoreceptors was determined by TUNEL(Terminal deoxynucleotidyl transferase dUTP nick end labeling) assay. ERK(Extracellular signal-regulated kinases), JNK, and SRC(sarcoma) expression were assessed by western blotting to determine regulated pathway. Blue light-injured retina were immunostained with antibodies against Opsin and Rhodopsin as markers of photoreceptors to compared the damage cone cells with rod cells. Results: After 1, 3 and 7 days from exposure to blue-light, thickness of retina was more decreased than control, and more decreased at nuclear layer than at outer plexiform layer and GFAP expression was increased day 1 after blue-light injured. While phosphorylated ERK and SRC protein expressions at day 1 were increased after blue-light injured, phosphorylated c-JUN was decreased. Fluorescence intensity analysis showed that markers of cone and rod cells were decreased after blue-light injured and Opsin was more decreased than Rhodopsin. Conclusions: The study suggests possibilities that the blue-light promotes retinal damage and causes apoptotic cell death via ERK and SRC pathway in mouse retina, and blue-light retinal damage is more induced cone cells apoptosis than rod cells directly.

• Journal of Photoscience
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• v.9 no.2
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• pp.246-248
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• 2002

Light is a major environmental signal for entrainment of the circadian clock, but little is known about the phototransduction pathway triggered by light-activation of photoreceptive molecule(s) responsible for the phase shift of the clock in vertebrates. The chicken pineal gland and retina contain the autonomous circadian oscillators together with the photic entrainment pathway, and hence they provide useful experimental model for the clock system. We previously demonstrated the expression and light-dependent activation of rod-type transducin $\alpha$-subunit (Gtl$\alpha$) in the chicken pineal gland. It is unlikely, however, that the pineal Gt$_1$$\alpha$ plays a major role in the photic entrainment, because the light-induced phase shift is unaffected by bloking the signaling function of Gt$_1$$\alpha$. Here, we show the expression of G 11 $\alpha$, an $\alpha$-subunit of another heterotrimeric G-protein, in the chicken pineal gland and retina by cDNA cloning, Northern blot and Western blot analyses. GIl$\alpha$-immunoreactivity was colocalized with pinopsin in the chicken pineal cells and it was found predominantly at the outer segments of photoreceptor cells in the retinal sections, suggesting functional coupling of G11 $\alpha$ with opsins in the both the tissues. By coimmunoprecipitation experiments using the retina, we showed the light- and GTP-dependent interaction between rhodopsin and G11 $\alpha$. Upon ectopic expression of a Gq/ 11-coupled receptor in cultured pineal cells, pharmacological (non-photic) activation of endogenous G11 induced phase-dependent phase shifts of the melatonin rhythm in a manner very similar to the effect of light. These results suggested opsin-G11 pathway contributing to the photic entrainment of the circadian clock.