SEARCH · Search PubMed

Results for “Rod Opsins”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources

PubMed2006

Casting a genetic light on the evolution of eyes.

Light has been exploited for information by organisms through the evolution of photoreceptors and, ultimately, eyes in animals. Only a handful of eye types exist because the physics of light constrains photodetection. In the past few years, genetic tools have revealed several parallel pathways through which light guides behavior and have provided insights into the convergent evolution of eyes. The gene encoding opsin (the primary phototransduction protein) and some developmental genes had very early origins and were recruited repeatedly during eye evolution. Eye lens proteins arose separately and make up a diverse group, many of which were co-opted from other functions. A major challenge now is understanding how newly discovered pathways for processing light evolved and how they collaborate with eyes to harvest information from light.

Animals↗

PubMed2003

Organ-specific gene expression in the rhesus monkey eye following intravenous non-viral gene transfer.

PURPOSE: The transfer of exogenous genes to the entire retina and other ocular structures is possible with a vascular route of gene delivery using a non-viral gene transfer method. The present studies examine the extent to which either beta-galactosidase or luciferase expression plasmids are targeted to the retina in the adult rhesus monkey following intravenous administration. In addition, these studies examine the pattern of organ expression of the transgene in the rhesus monkey depending on whether the plasmid is under the influence of a widely expressed promoter, the SV40 promoter, or an ocular-specific promoter, the opsin promoter. METHODS: The plasmid DNA with either the SV40 or opsin promoter is encapsulated in the interior of 85 nm pegylated immunoliposomes (PILs), which are targeted across the blood-retinal barrier and into ocular cells with a monoclonal antibody to the human insulin receptor. Following a single intravenous injection of the PIL carrying the transgene, the animals were sacrificed 2, 7, or 14 days later for the measurement of beta-galactosidase or luciferase gene expression in the monkey eye and peripheral organs. RESULTS: Histochemistry showed expression of the beta-galactosidase gene throughout the entire primate retina including the photoreceptor cells with either an SV40 or a bovine opsin promoter. Whereas the SV40 promoter enables gene expression in other organs of the primate (brain, liver, spleen), the opsin promoter restricted trans-gene expression to the primate eye, as there was no gene expressed in other organs. The retinal luciferase activity at 2 days after administration was 9.6+/-0.4 pg luciferase/mg protein, and at 14 days after administration was still comparable to maximal levels of luciferase gene expression in the mouse or rat. Confocal microscopy with antibodies to the insulin receptor and to beta-galactosidase demonstrated co-localization in the retina, with high expression of the trans-gene and the insulin receptor in the inner segments of the photoreceptor cells. CONCLUSIONS: The PIL non-viral gene transfer technology makes possible adult transgenics in 24 h. Ectopic expression of exogenous genes in organs other than the target organ is made possible with the use of organ specific promoters, and gene expression in the primate is restricted to the eye when the trans-gene is under the influence of the opsin promoter. Plasmid-based gene expression is still in the therapeutic range for 2-3 weeks after a single intravenous administration. Exogenous genes are expressed throughout the entire primate retina following the delivery of the gene to the eye via a trans-vascular route.

Animals↗

PubMed2006

The Drosophila rhodopsin cytoplasmic tail domain is required for maintenance of rhabdomere structure.

The ninaE-encoded Rh1 rhodopsin is the major light-sensitive pigment expressed in Drosophila R1-6 photoreceptor cells. Rh1 rhodopsin localizes to and is essential for the development and maintenance of the rhabdomere, the specialized membrane-rich organelle that serves as the site of phototransduction. We showed previously that the vertebrate bovine rhodopsin (Rho) is expressed and properly localized in Drosophila photoreceptor cells. Drosophila photoreceptors expressing only Rho have normal rhabdomere structure at young ages, but the rhabdomeres are not maintained and show extensive disorganization by 7-10 days of age. A series of Rho-Rh1 opsin chimeric rhodopsins were used to identify Rh1 domains required for maintenance of rhabdomeric structure. The results show that the Rh1 rhodopsin cytoplasmic tail domain, positioned to interact with cytoplasmic structural components, plays a major role in promoting rhabdomeric organization.

Amino Acid Motifs↗

PubMed2005

Impaired opsin targeting and cone photoreceptor migration in the retina of mice lacking the cyclic nucleotide-gated channel CNGA3.

PURPOSE: To characterize molecular and cellular changes in the mouse retina caused by the genetic deletion of the cone cyclic nucleotide-gated channel (CNG) subunit CNGA3. METHODS: Retinas of wild-type and CNGA3-deficient (CNGA3(-/-)) mice from 9 days up to 22 months of age were analyzed by immunohistochemistry, electron microscopy, and molecular biological methods. RESULTS: CNGA3(-/-) cones failed to transport opsins into outer segments, downregulated various proteins of the phototransduction cascade, and induced apoptotic death. Loss of CNGA3 did not affect the transcription of cone-specific genes. Cone degeneration was evident from the second postnatal week on, and it proceeded significantly faster in the ventral than in the dorsal part of the retina. Ventral cones were completely missing after the third postnatal month, whereas residual dorsal cones were present, even in 22-month-old knockout mice. CNGA3(-/-) cone somata exhibited profoundly delayed migration during postnatal development. At the time of eye opening, most CNGA3(-/-) cones had displaced somata localized close to or in the outer plexiform layer. These cones lacked the characteristic synaptic pedicle, but revealed synapselike contacts to second-order neurons at their somata. At later stages, most of the surviving CNGA3(-/-) cones had correctly located somata and morphologically normal synapses. CONCLUSIONS: The loss of CNGA3 impairs the targeting of cone opsins and the expression of other visual cascade proteins. In addition, CNGA3 appears to be essential for normal postnatal migration of cone somata. After loss of cone outer segment proteins, CNGA3(-/-) cones induce apoptotic cell death.

Animals↗

PubMed1999

Patterning of the R7 and R8 photoreceptor cells of Drosophila: evidence for induced and default cell-fate specification.

Opsin gene expression in the R7 and R8 photoreceptor cells of the Drosophila compound eye is highly coordinated. We have found that the R8 cell specific Rh5 and Rh6 opsins are expressed in non-overlapping sets of R8 cells, in a precise pairwise fashion with Rh3 and Rh4 in the R7 cells of individual ommatidia. Removal of the R7 cells in sevenless, boss or sina mutants, disrupts Rh5 expression and dramatically increases the number of Rh6-expressing R8 cells. This suggests that the expression of Rh5 may be induced by an Rh3-expressing R7 cell, whereas Rh6 expression is most likely a default state of the R8 cell. We found that the paired expression of opsin genes in the R7 and R8 cells occurs in a sevenless and boss independent manner. Furthermore, we found that the generation of both Rh3- and Rh4-expressing R7 cells can occur in the absence of an R8 cell. These results suggest that the specification of opsin expression in the R7 cells may occur autonomously, whereas the R7 photoreceptor cell may be responsible for regulating a binary developmental switch between induced and default cell-fates in the R8 cell.

Amino Acid Sequence↗

PubMed1997

Use of cell ELISA for the screening of neurotrophic activities on minor cell populations in retinal monolayer cultures.

In this study we describe a large-scale screening cell ELISA protocol which is suitable for the characterization of exogenic factor effects in mixed central nervous system (CNS) culture. The main novelty of the assay is that it permits the measurement of cellular responses in populations comprising as little as 2-4% of the total cell number. For standardization of the assay, we employed antibodies against opsin and microtubule-associated protein (MAP2) which label distinct retinal cell classes. Embryonic chick retinal neurons were grown in microtiter plates and directly processed for detection of antibody binding on the same plate. Binding of the antibodies was saturable and the ELISA signal was proportional to the number of immunoreactive cells comprising 2-4% and 16% of the total cell number with opsin and MAP2 antibodies, respectively. A minimum of 2000 opsin-positive cells could be reliably determined. Using our cell ELISA protocol, we demonstrate a developmental increase of both cell markers which reflected an increase in the number of opsin-positive cells but an enhanced expression per cell in the case of MAP2. We also show that growth-promoting activity-the presumed chick ciliary neurotrophic factor (CNTF)-stimulated the expression of opsin in retinal cultures (EC50; 2.3 pM) and that a corresponding activity is specifically expressed in the developing retina. Our results show that the cell ELISA protocol allows the rapid screening for distinct, low-percentage cell populations responding to exogenous factors in mixed CNS cultures.

Animals↗

PubMed1995

Initial mutational steps toward loss of opsin gene function in cavefish.

The river-dwelling fishes of Astyanax fasciatus and their derivatives from Pachon and Micos caves in Mexico were collected. By comparing red (r007) and green (g103) opsin gene sequences from the three populations, we found a high frequency of C-->T changes in r007 and g103 of the eyed Micos fishes presumably due to spontaneous cytosine methylation or enzymatic deamination of the CG dinucleotide, and a deletion of 12 consecutive nucleotides in g101 of the blind Pachon fishes. Thus, high rates of nucleotide substitution and C-->T transitions, usually found for pseudogenes, may occur even before they become nonfunctional.

Animals↗

PubMed1993

Differential expression of interphotoreceptor retinoid-binding protein, opsin, cellular retinaldehyde-binding protein, and basic fibroblastic growth factor.

The mRNA for rat interphotoreceptor retinoid-binding protein (IRBP) consists of 5.2 kb and 6.4 kb transcripts which are expressed early during retinal development. Here, we characterized rat IRBP cDNA and genomic clones, determined the mechanism generating the two transcripts and compared their expression to mRNAs for opsin, cellular retinaldehyde-binding protein (CRAlBP) and basic fibroblast growth factor (bFGF). We found that human and rat IRBPs have a high degree of sequence homology (86% amino acid identity over the fourth repeat). RNA-PCR studies and Northern blot analysis, showed that the 6.4 kb mRNA has a longer 3'-untranslated region (UTR) than the 5.2 kb message. Both IRBP transcripts, but not the mRNA for opsin are present in the neonatal and adult pineal. During development, the mRNAs for IRBP and opsin reach one-half of their maximal levels by P5 and P11, respectively. The ratio of the two IRBP mRNAs remains constant throughout life. In contrast, the ratio of the longest to the shortest opsin mRNA decreases between E19 and 1 year of age. Immunohistochemistry demonstrated a marked increase in the amount of IRBP in the interphotoreceptor matrix between P1 and P9 corresponding to the enhanced expression of this mRNA. Up-regulation of opsin mRNA expression during the second postnatal week corresponds to the emergence of the outer segments. The temporal expression of CRAlBP is similar to IRBP while bFGF is not expressed until after photoreceptor differentiation is complete. In summary, two 3'-transcription termination sites explain the difference in IRBP mRNA sizes. The different temporal and tissue specific patterns of IRBP and opsin expression suggest that separate mechanisms control the expression of these two genes. The expression patterns of IRBP and CRAlBP are consistent with the role of vitamin A as a morphogen and bFGF in neuronal maintenance.

Age Factors↗

PubMed1994

Sequence divergence, polymorphism and evolution of the middle-wave and long-wave visual pigment genes of great apes and Old World monkeys.

In man, the spectral shift between the middle-wave (MW) and long-wave (LW) visual pigments is largely achieved by amino acid substitution at two codons, both located in exon 5. A third amino acid site coded by exon 3 is polymorphic between pigments. We have studied the equivalent regions of the cone opsin genes in two members of the Hominidea (the gorilla, Gorilla gorilla and the chimpanzee, Pan troglodytes) and in three members of the Cercopithecoidea family of Old World primates (the diana monkey, Cercopithecus diana, the talapoin monkey, Miopithecus talapoin, and the crab-eating macaque, Macaca fascicularis). No variation in the codons that specify the amino acids involved in spectral tuning were found. We predict therefore that the MW and LW pigments of gorilla and chimpanzee have similar spectral characteristics to those of man. Multiple copies of the same opsin gene sequence were identified in the chimpanzee, talapoin and macaque and we also show that non-human Old World primates are similar to man in showing a bunching of polymorphic sites in exon 3. We discuss the ancestry of the separate MW and LW genes of Old World primates and the equivalent polymorphic gene of the marmoset, a New World primate.

Amino Acid Sequence↗

PubMed1998

A deep brain photoreceptive molecule in the toad hypothalamus.

We have isolated a cDNA clone encoding a deep brain photoreceptive molecule from the hypothalamic cDNA library of the toad, Bufo japonicus. The deduced amino acid sequence showed the highest similarity to that of pinopsin (75-76%) among vertebrate retinal opsins, indicating the expression of toad pinopsin in the deep brain. Antibodies raised against the C-terminal tail of toad pinopsin stained cell bodies and the knob-like structures of the cerebrospinal fluid-contacting neurons in the anterior preoptic nucleus. This region is known to play an important role in breeding behavior, suggesting that toad pinopsin acts as a photosensor for the photoperiodic gonadal response.

Amino Acid Sequence↗

PubMed1998

The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (Melopsittacus undulatus).

Microspectrophotometric (msp) studies have shown that the colour-vision system of many bird species is based on four pigments with absorption peaks in the red, green, blue and UV regions of the spectrum. The existence of a fourth pigment (UV) is the major difference between the trichromacy of humans and the tetrachromacy of such birds, and recent studies have shown that it may play a determining role in such diverse aspects of behaviour as mate selection and detection of food. Avian visual pigments are composed of an opsin protein covalently bound via a Schiff-base linkage to the chromophore 11-cis-retinal. Here we report the cDNA sequence of a UV opsin isolated from an avian species, Melopsittacus undulatus (budgerigar or small parakeet). This sequence has been expressed using the recombinant baculovirus system; the pigment generated from the expressed protein on addition of 11-cis-retinal yielded an absorption spectrum typical of a UV photopigment, with lambdamax 365+/-3 nm. This is the first UV opsin from an avian species to be sequenced and expressed in a heterologous system. In situ hybridization of this sequence to budgerigar retinas selectively labelled a sub-set of UV cones, representing approx. 9% of the total cone population, that are distributed in a semi-regular pattern across the entire retina.

Amino Acid Sequence↗

PubMed1999

Enhanced retinal longwave sensitivity using a chlorophyll-derived photosensitiser in Malacosteus niger, a deep-sea dragon fish with far red bioluminescence.

Through partial bleaching of both visual pigment extracts and cell suspensions we show that the deep-sea stomiid Malacosteus niger, which produces far red bioluminescence, has two visual pigments within its retina which form a rhodopsin/porphyropsin pigment pair with lambda max values around 520 and 540 nm, but lacks the very longwave sensitive visual pigments (lambda max > 550 nm) observed in two other red light producing stomiids. The presence of only a single opsin gene in the M. niger genome was confirmed by molecular and cladistic analysis. To compensate for its apparently reduced longwave sensitivity compared to related species, the outer segments of M. niger contain additional pigments, which we identify as a mixture of defarnesylated and demetallated derivatives of bacteriochlorophylls c and d, that are used as a photosensitiser to enhance its sensitivity to longwave radiation.

Animals↗

PubMed2003

Light-induced phase shift in the Syrian hamster (Mesocricetus auratus) is attenuated by the PACAP receptor antagonist PACAP6-38 or PACAP immunoneutralization.

Circadian rhythms generated by the suprachiasmatic nucleus (SCN) are daily adjusted (entrained) by light via the retinohypothalamic tract (RHT). The RHT contains two neurotransmitters, glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP), which are believed to mediate the phase-shifting effects of light on the clock. In the present study we have elucidated the role of PACAP in light-induced phase shifting at early night in hamsters and shown that (i) light-induced phase delay of running-wheel activity was significantly attenuated by a specific PAC1 receptor antagonist (PACAP6-38) or by immunoblockade with a specific anti-PACAP antibody injected intracerebroventricularly before light stimulation; (ii) PACAP administered close to the SCN was able to phase-delay the circadian rhythm of running-wheel activity in a similar way to light; (iii) PACAP was present in the hamster RHT, colocalized with melanopsin, a recently identified opsin which has been suggested to be a circadian photopigment. The findings indicate that PACAP is a neurotransmitter of the RHT mediating photic information to the clock, possibly via melanopsin located exclusively on the PACAP-expressing cells of the RHT.

Animals↗

PubMed1998

The rhodopsin gene of the cuttlefish Sepia officinalis: sequence and spectral tuning.

The cephalopod molluscs are a group of invertebrates that occupy a wide range of oceanic photic environments. They are an ideal group of animals, therefore, in which to study the evolution of rhodopsin. The cDNA sequence of the rhodopsin gene of the cuttlefish Sepia officinalis (L.) (Sub-class Coleoidea, Order Sepiida) is presented, together with an analysis of the structure of the gene. A proline-rich C terminus is present; this structure is characteristic of cephalopod rhodopsins. In common with all invertebrate opsins studied so far, the equivalent site to the counterion in vertebrate opsins is occupied by an aromatic amino acid. An intron is present that splits codon 107, in contrast to the intronless rhodopsin gene in two species of myopsid squid. A spectral tuning model involving substitutions at only three amino acid sites is proposed for the spectral shifts between the rhodopsins of Sepia officinalis, three species of squid and Paroctopus defleini.

Amino Acid Sequence↗

PubMed1998

Cloning and expression of a Xenopus short wavelength cone pigment.

The short wavelength visual pigment from Xenopus responsible for vision in the blue/violet portion of the spectrum was characterized by sequence spectroscopic analysis. The amino acid sequence was deduced by sequencing clones isolated by reverse transcription PCR, from retinal cDNA and genomic libraries. The gene contains 5 exons spanning 8.4 kb of genomic DNA and produces an mRNA of 2.4 kb in length. The deduced amino acid sequence predicts a protein of 347 amino acids with 76-78% identity to other short wavelength opsins. The mRNA encoding the Xenopus violet pigment was detected using in situ hybridization in cones, comprising a few percent of the total photoreceptors in the adult retina. The Xenopus violet opsin cDNA, modified to contain an epitope from the carboxyl terminus of bovine rhodopsin, was expressed in COS1 cells by transient transfection and analysed by UV-visible absorption spectroscopy. The protein expressed in COS1 cells migrated at 34 kD and was glycosylated at a single site in the amino terminus, exhibiting a diffuse pattern on SDS PAGE similar to bovine rhodopsin expressed in COS1 cells. Following incubation with 11-cis retinal, a light-sensitive pigment was formed with the lambdamax=425+/-2 nm. A Schiff base linkage between retinal and the violet opsin was demonstrated by acid denaturation. Xenopus violet opsin was sensitive to hydroxylamine in the dark, reacting with a half-time of 5 min at room temperature. This is the first group S pigment for amphibians. The pigment was expressed and purified from COS1 cells in a form that has permitted for the first time determination of the extinction coefficient, reactivity to hydroxylamine and presence of a Schiff base.

Amino Acid Sequence↗

PubMed2005

[Molecular dynamics simulation of dark-adapted rhodopsin and free opsin].

Molecular dynamics simulation was carried out for the rhodopsin protein to investigate its conformational changes in respect to inclusion of 11-cis retinal chromophore. Molecular dynamics calculations were performed within the time frame 3000 ps. Totally, 3 X 10(6) configurations ofrhodopsin and free opsin were analyzed and compared. It has been shown that the 11-cis retinal rearrangement (adaptation) in opsin strongly affects the surrounding amino acid residues of protein binding pocket and the protein cytoplasmic region. The extracellular part, however, shows comparatively little changes. On basis of the simulation results obtained we propose a molecular mechanism for the rhodopsin protein function as a G-protein-coupled receptor in the state of darkness. We discuss the role of the retinal chromophore as a ligand-antagonist stabilizing the inactive conformation of rhodopsin.

Animals↗

PubMed1990

Immunohistochemical studies of retinoblastoma.

Various immunohistochemical markers were detected in 27 cases of human retinoblastoma by immunohistochemical avidin-biotin-peroxidase complex and peroxidase-antiperoxidase techniques using mono- and polyclonal antibodies. The glial markers, glial fibrillary acidic protein and Leu-7, were detected in the natural retinal component and perivascular glial cells within the tumor mass. In 4 among 27 cases Leu-7 was positive in the glial cells which were interspersed randomly among tumor cells and not associated with blood vessels. The neural marker, neuron-specific enolase, stained strongly positive in undifferentiated tumor cells and weakly positive in rosettes and fleurettes in most of the cases (21/27). Opsin, the photoreceptor marker, which is present only in the outer segment of photoreceptor cells, was detected in tumor cells of fleurettes in one case and also in rosettes in 6 cases. These results support the view that retinoblastoma has a predominantly neuronal nature with significant photoreceptor-like differentiation and rarely glial differentiation.

Adult↗

PubMed2002

The circadian photopigment melanopsin is expressed in the blind subterranean mole rat, Spalax.

Despite severe degeneration of its eyes, the blind subterranean mole rat, Spalax, is able to adjust circadian rhythms to the environmental light/dark cycle due to a conserved retinohypothalamic tract (RHT). The photopigment mediating the circadian photoreception and it cellular localisation is unknown in the Spalax retina. Here we show, using in situ hybridization and immunohistochemistry, that melanopsin, a recently identified opsin, is expressed in retinal ganglion cells which also co-store PACAP, a neurotransmitter of the RHT. The melanopsin-component of retinal ganglion cells in the Spalax retina is well conserved resulting in a relatively higher density of melanopsin positive cells per area compared to the rat. The results show that the Spalax, as sighted animals expresses melanopsin in ganglion cells projecting to the circadian clock supporting a role of melanopsin as a circadian photopigment.

Animals↗