Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Retinal Rod Photoreceptor Cells”

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.

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

At least 667 records · Page 37Linked to original sources
PubMedDate not supplied

Photoreceptor types and distributions in the retinae of insectivores.

The retinae of insectivores have been rarely studied, and their photoreceptor arrangements and expression patterns of visual pigments are largely unknown. We have determined the presence and distribution of cones in three species of shrews (common shrew Sorex araneus, greater white-toothed shrew Crocidura russula, dark forest shrew Crocidura poensis; Soricidae) and in the lesser hedgehog tenrec Echinops telfairi (Tenrecidae). Special cone types were identified and quantified in flattened whole retinae by antisera/antibodies recognizing the middle-to-long-wavelength-sensitive (M/L-)cone opsin and the short-wavelength-sensitive (S-)cone opsin, respectively. A combination of immunocytochemistry with conventional histology was used to assess rod densities and cone/rod ratios. In all four species the rods dominate at densities of about 230,000-260,000/mm2. M/L- and S-cones are present, comprising between 2% of the photoreceptors in the nocturnal Echinops telfairi and 13% in Sorex araneus that has equal diurnal and nocturnal activity phases. This suggests dichromatic color vision like in many other mammals. A striking feature in all four species are dramatically higher S-cone proportions in ventral than in dorsal retina (0.5% vs. 2.5-12% in Sorex, 5-15% vs. 30-45% in Crocidura poensis, 3-12% vs. 20-50% in Crocidura russula, 10-30% vs. 40-70% in Echinops). The functional and comparative aspects of these structural findings are discussed.

Animals↗
PubMed2005

Morphological changes in the anterior segment of the Abyssinian cat eye with hereditary rod-cone degeneration.

PURPOSE: The purpose of this study was to investigate morphological changes of the anterior segment of the eye in Abyssinian cats with progressive rod-cone degeneration and to correlate them with blood flow data obtained in the same animals. METHODS: Sections of the left eyes of six normal cats and of eight cats with different stages of hereditary retinal degeneration were prepared for transmission and scanning electron microscopy. Tangential and sagittal sections were also stained with antibodies against substance P, tyrosine hydroxylase, panneuronal marker PGP9.5, nitric oxide synthase, synaptophysin, and smooth muscle alpha-actin. RESULTS: In Abyssinian cats with hereditary rod-cone degeneration, significant changes were observed in the iris consisting of irregularities in the vascular wall of smaller arteries without changes in their innervation pattern. The ciliary processes were shorter than in normal cats, and their structure appeared more compact and retracted. Slight changes were also observed in the anterior part of the ciliary epithelium. The anterior chamber angle region did not appear to be affected. CONCLUSIONS: Clear morphological correlations to the physiological blood flow data were observed in the anterior eye segment, pointing not only to functional but also morphological vascular abnormalities in this animal model for retinitis pigmentosa.

Animals↗
PubMed2001

A novel Gly35Ser mutation in the RDH5 gene in a Japanese family with fundus albipunctatus associated with cone dystrophy.

OBJECTIVE: To assess the clinical and genetic characteristics of a Japanese family with fundus albipunctatus with progressive cone dystrophy associated with a mutation in the RDH5 gene. DESIGN: Case report with clinical findings and results of fluorescein angiography, electroretinograms, kinetic visual field testing, dark adaptometry, and DNA analysis. SETTING: University medical center. PATIENTS: We studied the ocular findings in 6 members of a Japanese family with fundus albipunctatus with cone dystrophy and a guanine-to-adenine transversion at the first nucleotide in codon 35 of the RDH5 gene. The mutation resulted in a substitution of serine for glycine in amino acid 35 (Gly35Ser) of the RDH5 gene. RESULTS: Characteristic features included poor night vision, white dots in the retina, cone dystrophy, and a mottled appearance of the retinal pigment epithelium. Electroretinograms showed greater impairment of the rod-mediated responses than the cone-mediated responses. After 3 hours of dark adaptation, the a and b waves and scotopic b waves recovered. CONCLUSIONS: Although the mutation of the RDH5 gene has been known as a causative gene of fundus albipunctatus, the Gly35Ser mutation in the RDH5 gene may be related to the pathogenesis of progressive retinal degeneration. This phenomenon may provide evidence of gene phenotype caused by a mutation in the RDH5 gene. CLINICAL RELEVANCE: The Gly35Ser mutation causes fundus albipunctatus with cone dystrophy. This finding provides evidence that some kinds of mutations in the RDH5 gene are related, in part at least, to the pathogenesis of progressive retinal degeneration.

Alcohol Oxidoreductases↗
PubMed1995

An alternative pathway for signal flow from rod photoreceptors to ganglion cells in mammalian retina.

Rod signals in the mammalian retina are thought to reach ganglion cells over the circuit rod-->rod depolarizing bipolar cell-->AII amacrine cell-->cone bipolar cells-->ganglion cells. A possible alternative pathway involves gap junctions linking the rods and cones, the circuit being rod-->cone-->cone bipolar cells-->ganglion cells. It is not clear whether this second pathway indeed relays rod signals to ganglion cells. We studied signal flow in the isolated rabbit retina with a multielectrode array, which allows the activity of many identified ganglion cells to be observed simultaneously while the preparation is stimulated with light and/or exposed to drugs. When transmission between rods and rod depolarizing bipolar cells was blocked by the glutamate agonist 2-amino-4-phosphonobutyric acid (APB), rod input to all On-center and briskly responding Off-center ganglion cells was dramatically reduced as expected. Off responses persisted, however, in Off-center sluggish and On-Off direction-selective ganglion cells. Presumably these responses were generated by the alternative pathway involving rod-cone junctions. This APB-resistant pathway may carry the major rod input to Off-center sluggish and On-Off direction-selective ganglion cells.

Aminobutyrates↗
PubMed2004

Multiple cone visual pigments and the potential for trichromatic colour vision in two species of elasmobranch.

Elasmobranchs (sharks, skates and rays) are the modern descendents of the first jawed vertebrates and, as apex predators, often occupy the highest trophic levels of aquatic (predominantly marine) ecosystems. However, despite their crucial role in the structure of marine communities, their importance both to commercial and to recreational fisheries, and the inherent interest in their role in vertebrate evolution, very little is known about their visual capabilities, especially with regard to whether or not they have the potential for colour vision. Using microspectrophotometry, we show that the retinae of the giant shovelnose ray (Rhinobatos typus) and the eastern shovelnose ray (Aptychotrema rostrata) contain three spectrally distinct cone visual pigments with wavelengths of maximum absorbance (lambdamax) at 477, 502 and 561 nm and at 459, 492 and 553 nm, respectively. The retinae of R. typus and A. rostrata also contain a single type of rod visual pigment with lambdamax at 504 and 498 nm, respectively. R. typus, living in the same estuarine waters as A. rostrata, were found to have identical visual pigments to R. typus inhabiting coral reef flats, despite a considerable difference in habitat spectral radiance. This is the first time that multiple cone visual pigments have been measured directly in an elasmobranch. The finding raises the possibility that some species are able to discriminate colour--a visual ability traditionally thought to be lacking in this vertebrate class--and it is evident that the visual ecology of elasmobranchs is far more complex than once thought.

Animals↗
PubMed1994

Cell adhesion molecules regulating neurite growth from amacrine and rod photoreceptor cells.

A great deal is now known about the cell adhesion molecules (CAMs) that are responsible for promoting the growth of ganglion cell axons as they project out of the retina through the optic nerve and finally to distant targets in the brain. However, the CAMs important for regulating axon outgrowth from nonprojection neurons, such as amacrine cells and rods, are not known. Such local circuit neurons extend their neurites rather short distances on cellular surfaces not normally encountered by the ganglion cell axons. To study the mechanisms regulating axon or dendrite growth from local circuit neurons, neurite outgrowth from amacrine cells and rod photoreceptor cells derived from the rat was examined in vitro on immunopurified forms of NCAM, L1, and N-cadherin, three well-characterized adhesive molecules found in the developing retina. Either early (P3) or late (P10) postnatal amacrine cells grew neurites on all three CAMs, but there were significant differences in the percentage of the amacrine cells that responded to each CAM. None of the CAMs supported neurite outgrowth from early postnatal rods, but, surprisingly, NCAM stimulated vigorous neurite extension from rods isolated at postnatal day 10. Postnatal ganglion cells were also examined for comparison and were found not to grow neurites on NCAM, but did grow extensive processes on L1 and N-cadherin. These results show that NCAM, L1, and N-cadherin can promote neurite outgrowth from local circuit neurons, but that the effectiveness of any particular CAM is dependent on the cell type and the developmental period.

Animals↗
PubMed1994

Spectral characteristics of visual pigments in rainbow trout (Oncorhynchus mykiss).

We investigated retina preparations of young rainbow trout (Oncorhynchus mykiss) with body wt 5-40 g. Rods, single and double cones were measured in side-on orientation by microspectrophotometry, identifying five spectrally distinct visual pigments (or photoreceptors containing mixtures of visual pigments). The mean wavelength of peak absorbance (lambda max) of the alpha-bands were 365 and 434 nm in single cones, 531 and 576 nm in double cones, and 521 nm in the rods. The half-band width (HBW) of the main absorption bands were broader than expected of retinal- (vitamin A1-) based visual pigments, and thus, they were indicative of a mixed chromophore pool derived from both the vitamin A1 and A2 forms. One consequence of the utilization of mixed chromophores is the broadening of the alpha-band absorption in each pigment type. And yet, we obtained exceptionally narrow HBW for the UV-type pigment, when compared with HBW values expected on the basis of the linear trend seen in visual pigments absorbing in the visible spectrum. We conclude that the UV pigment in rainbow trout has an unusually narrow HBW. Nevertheless, this species is not exceptional in this regard, for the UV-absorbing visual pigments in other vertebrate species also have narrow HBW.

Animals↗
PubMed2006

Efficiency of synaptic transmission of single-photon events from rod photoreceptor to rod bipolar dendrite.

A rod transmits absorption of a single photon by what appears to be a small reduction in the small number of quanta of neurotransmitter (Q(count)) that it releases within the integration period ( approximately 0.1 s) of a rod bipolar dendrite. Due to the quantal and stochastic nature of release, discrete distributions of Q(count) for darkness versus one isomerization of rhodopsin (R*) overlap. We suggested that release must be regular to narrow these distributions, reduce overlap, reduce the rate of false positives, and increase transmission efficiency (the fraction of R* events that are identified as light). Unsurprisingly, higher quantal release rates (Q(rates)) yield higher efficiencies. Focusing here on the effect of small changes in Q(rate), we find that a slightly higher Q(rate) yields greatly reduced efficiency, due to a necessarily fixed quantal-count threshold. To stabilize efficiency in the face of drift in Q(rate), the dendrite needs to regulate the biochemical realization of its quantal-count threshold with respect to its Q(count). These considerations reveal the mathematical role of calcium-based negative feedback and suggest a helpful role for spontaneous R*. In addition, to stabilize efficiency in the face of drift in degree of regularity, efficiency should be approximately 50%, similar to measurements.

Animals↗
PubMed2004

Progressive cone dystrophy associated with mutation in CNGB3.

PURPOSE: To determine the molecular basis for phenotypic variability in a three-generation consanguineous family containing a single individual with complete achromatopsia and three individuals with progressive cone dystrophy. METHODS: Four affected individuals underwent ophthalmic examination, electrophysiological assessment, color fundus photography, and psychophysical testing. Blood samples were obtained for DNA extraction and mutation screening of the cone-specific cGMP-gated (CNG) channel protein gene CNGB3 was undertaken. RESULTS: The clinical findings in one family member were consistent with a diagnosis of complete achromatopsia, with nystagmus, photophobia, and poor visual acuity from early infancy and complete color-blindness, normal fundi, and absent cone responses with normal rod responses on electroretinography (ERG). Mutation analysis revealed her to be homozygous for the common CNGB3 achromatopsia mutation, 1148delC (Thr383fs). In contrast, the three other symptomatic individuals in the family had findings consistent with progressive cone dystrophy. Their visual problems began later in childhood (ranging from 3 to 14 years of age) and there was evidence of progressive deterioration in cone function. All three had a marked tritanopic color vision defect and fundoscopy revealed bilateral macular atrophy. Electrophysiological testing of these three subjects demonstrated clear evidence of progressive deterioration of cone responses over time; rod responses were normal. All three individuals with this progressive phenotype were found to be compound heterozygotes for the 1148delC (Thr383fs) frameshift mutation and a novel Arg403Gln missense mutation in CNGB3. CONCLUSIONS: Mutations in CNGB3, which have been shown to cause achromatopsia, are now shown to be associated with autosomal recessive progressive cone dystrophy. In this study, a novel Arg403Gln mutation was identified, located in the middle of the pore domain of the cone CNG cation channel beta-subunit, which when associated with the nonsense mutation Thr383fs, resulted in progressive cone dystrophy.

Adult↗
PubMed2002

Isomerization and oxidation of vitamin a in cone-dominant retinas: a novel pathway for visual-pigment regeneration in daylight.

The first step toward light perception is 11-cis to all-trans photoisomerization of the retinaldehyde chromophore in a rod or cone opsin-pigment molecule. Light sensitivity of the opsin pigment is restored through a multistep pathway called the visual cycle, which effects all-trans to 11-cis re-isomerization of the retinoid chromophore. The maximum throughput of the known visual cycle, however, is too slow to explain sustained photosensitivity in bright light. Here, we demonstrate three novel enzymatic activities in cone-dominant ground-squirrel and chicken retinas: an all-trans-retinol isomerase, an 11-cis-retinyl-ester synthase, and an 11-cis-retinol dehydrogenase. Together these activities comprise a novel pathway that regenerates opsin photopigments at a rate 20-fold faster than the known visual cycle. We suggest that this pathway is responsible for sustained daylight vision in vertebrates.

Animals↗
PubMed1999

The effects of temperature on the dark-adapted spectral sensitivity function of the adult zebrafish.

In goldfish and other cold-blooded vertebrates, temperature can influence the rhodopsin/porphyropsin contributions to the rod photoreceptors. This study examined the effects of temperature on the spectral sensitivity function of the dark-adapted zebrafish. Zebrafish were housed in either a warm (28-30 degrees C) or cold (22-25 degrees C) tank prior to testing. Fish were dark-adapted for at least 1 h and electroretinogram (ERG) responses to 200 ms stimuli of various wavelengths and irradiances were obtained. Results show that water temperature affected the spectral sensitivity function of the ERG b-wave. Subjects housed in the warm temperatures had a spectral sensitivity consistent with the rhodopsin absorption curve; however, fish housed in the colder temperatures had a spectral sensitivity function that was the result of a rhodopsin/porphyropsin mixture. In addition, ultraviolet cones (lambda max: 362 nm) contributed to the dark-adapted spectral sensitivity function under both temperature conditions. Consistent with the results from other fish, the dark-adapted visual system of the zebrafish can be influenced by water temperature. The results of this study demonstrate the necessity of maintaining a stable environment when examining the contributions of the photoreceptors to the visual response.

Adaptation, Ocular↗
PubMed2000

Visual pigments, oil droplets, ocular media and cone photoreceptor distribution in two species of passerine bird: the blue tit (Parus caeruleus L.) and the blackbird (Turdus merula L.).

The spectral absorption characteristics of the retinal photoreceptors of the blue tit (Parus caeruleus) and blackbird (Turdus merula) were investigated using microspectrophotometry. The retinae of both species contained rods, double cones and four spectrally distinct types of single cone. Whilst the visual pigments and cone oil droplets in the other receptor types are very similar in both species, the wavelength of maximum sensitivity (lambda(max)) of long-wavelength-sensitive single and double cone visual pigment occurs at a shorter wavelength (557 nm) in the blackbird than in the blue tit (563 nm). Oil droplets located in the long-wavelength-sensitive-single cones of both species cut off wavelengths below 570-573 nm, theoretically shifting cone peak spectral sensitivity some 40 nm towards the long-wavelength end of the spectrum. This raises the possibility that the precise lambda(max) of the long-wavelength-sensitive visual pigment is optimised for the visual function of the double cones. The distribution of cone photoreceptors across the retina, determined using conventional light and fluorescence microscopy, also varies between the two species and may reflect differences in their visual ecology.

Absorption↗
PubMed1999

Visual pigments and oil droplets in the retina of a passerine bird, the canary Serinus canaria: microspectrophotometry and opsin sequences.

The visual receptors of the passeriform bird Serinus canaria, the canary, have been examined microspectrophotometrically and the sequences of the opsins determined. Rods have a maximum absorbance (lambda max) at 506 nm. Four spectral classes of single cone are present: long-wave-sensitive (LWS) containing a photopigment with lambda max at 569 nm, middle-wave-sensitive (MWS) with lambda max at 505 nm, short-wave-sensitive (SWS) with lambda max at 442 nm, and ultraviolet-sensitive (UVS) with lambda max at about 366 nm. Double cones possess the 569-nm pigment in both members. Typical combinations of photopigment and oil droplet occur in most cone classes. An ambiguity exists in the oil droplet of the single LWS cones. In some birds, LWS cones are paired with an R-type droplet, whereas in the majority of canaries the LWS pigment is paired with a droplet similar to the P-type of double cones. Mechanisms of spectral tuning within each opsin class are discussed.

Animals↗
PubMedDate not supplied

Visual pigments, cone oil droplets and ocular media in four species of estrildid finch.

A microspectrophotometric study was conducted on the retinal photoreceptors of four species of bird: cut-throat finches (Amadina fasciata), gouldian finches (Erythrura gouldiae), white-headed munias (Lonchura maja) and plum-headed finches (Neochmia modesta). Spectral characteristics of the photoreceptors in all four species were very similar. Rods contained a medium-wavelength-sensitive visual pigment with a wavelength of maximum absorbance at 502-504 nm. Four spectrally distinct types of single cone contained a visual pigment with wavelength of maximum absorbance at either 370-373 nm (ultraviolet-sensitive), 440-447 nm (short-wavelength-sensitive); 500 nm (medium-wavelength-sensitive) or 562-565 nm (long-wavelength-sensitive). Oil droplets in the ultraviolet-sensitive single cones showed no detectable absorption between 330 nm and 800 nm. Oil droplets in the short-, medium-, and long-wavelength-sensitive single cones had cut-off wavelengths at 415-423 nm, 510-520 nm and 567-575 nm, respectively. Double cones contained the visual pigment with wavelength of maximum absorbance at 562-565 nm observed in long-wavelength-sensitive single cones. Only the principal member of the double cone pair contained an oil droplet (P-type, cut-off wavelength at 414-489 nm depending on species and retinal location). Spectral transmittance of the intact ocular media of each species was measured along the optic axis. Wavelengths of 0.5 transmittance for all species were very similar (316-318 nm).

Animals↗
PubMed1998

The photoreceptor mosaic.

The organisation of the human photoreceptor mosaic reflects evolutionary strategies for optimising visual information under a wide range of stimulus conditions: (1) The rod population dominates (max. 170,000/mm2 at c. 30 degrees sup.) except for the central 2 degrees and along the ora serrata. (2) Density of cone inner/outer segments reaches up to 300,000 mm2 in the fovea. A bundle of c. 300-500 foveolar cones are further distinguished by having their synaptic terminals located within the capillary-free zone. Radial displacement (> 350 microns) of foveal cone terminals may result in the lesion of two sets of cone pathways by perifoveal laser treatment. Along the ora serrata peripheral cone density (c. 4000) rises within a small rim (1 degree) to up to 20,000, but may be considerably decreased by cystoid degenerations. For the L- and M-cone subpopulations ratios of 2:1 to 1:1 and random arrangement are suggested. (3) Blue-sensitive (S-) cones constitute a regular and independent submosaic of c. 7% across the periphery. An annular maximum (1000-5000/mm2) at c. 1 degree surrounds the foveola. There density decreases and irregular zones lacking S-cones result in tritan deficiencies.

Aging↗
PubMed1997

Structure and analysis of the transducin beta3-subunit gene, a candidate for inherited cone degeneration (cd) in the dog.

The cDNA for the beta3-subunit of cone-specific transducin (Tbeta3) was cloned and characterized from wild type dogs, and used in linkage studies as a candidate gene for cone degeneration. Sequence analysis of the Tbeta3 cDNA revealed an open reading frame of 1020 bp, potentially coding for a protein of 340 amino acids (aa). The deduced aa sequence of canine Tbeta3 shares 97% identity with the previously identified human Tbeta3, and 82% identity with bovine rod-specific transducin (Tbeta1). RT-PCR and sequencing of the amplified products demonstrated that the retinal canine Tbeta3 gene is expressed in two different transcripts which can be generated by alternative splicing of the intron in the 3'-untranslated region (UTR). The short and the long mRNAs differ in the length of their 3'-UTR by 456 nt. We have also determined the genomic organization of the canine Tbeta3 gene; it consists of ten exons and the first exon is in the 5'-UTR. The cDNA encoding Tbeta3 from cd-affected dogs was also cloned and sequenced. We found no differences at the nucleotide level between the cDNAs isolated from normal and diseased retinas. The level of transcription of Tbeta3 mRNA in the cd dog retina appeared to be normal. Linkage analysis of a crossbred informative pedigree showed five obligate recombinants out of nine informative offspring. These results suggest that Tbeta3 is not a candidate gene for the cone degeneration of the cd mutant.

Amino Acid Sequence↗
PubMed1993

Red blood cell fatty acid levels in patients with autosomal dominant retinitis pigmentosa.

Fatty acid profiles were determined in red blood cell (RBC), plasma lipids and lipid fractions from 50 patients with autosomal dominant retinitis pigmentosa (ADRP) and 20 normal-sighted controls. In plasma of affected patients, significant increases in omega 6 long-chain derivatives compared to controls resulted in elevated fatty acid unsaturation whereas, in RBCs, significant decreases in the levels of omega 6 and omega 3 long-chain polyunsaturates and a reduced unsaturation index were demonstrated (P < 0.01). The disproportionate levels of long-chain fatty acids in plasma vs. RBCs were consistent with abnormal function of acyl group transfer from plasma lipids to target tissues such as RBCs or, possibly, retina. Metabolic lipid anomalies were evaluated in two sub-groups of patients with ADRP; ten with the highest and ten with the lowest RBC lipid levels of the omega 3 fatty acid, docosahexaenoic acid (DHA). Fatty acid product/precursor relationships in the sub-groups revealed reduced chain elongation and omega 3 fatty acid desaturation associated with reduced ratios of rod-to-cone electroretinographic amplitudes. Based on these results, we suggest that the heterogenic ADRP population includes a sub-group of patients characterized by abnormal fatty acid metabolism that may effect membrane structure and visual function.

Adolescent↗
PubMedDate not supplied

Clinical heterogeneity between two Japanese siblings with congenital achromatopsia.

Congenital achromatopsia is a stationary retinal disorder with autosomal recessive inheritance. It is characterized by significant attenuation of cone-photoreceptor function. Symptoms include photophobia, nystagmus, and poor visual acuity from birth. Unlike in cone or cone-rod dystrophies, the retinal fundus usually appears normal. Here we describe two siblings with congenital achromatopsia, who exhibit different ophthalmic phenotypes. History was taken, and ophthalmic examinations were performed in a 7-year-old girl and her 5-year-old brother, who were referred to our department because of poor visual acuity. Two of their grandparents were brother and sister, suggesting an autosomal recessive transmission in inheritance. They have been followed for more than 13 years since the initial evaluation. Symptoms, visual acuity, and kinetic visual field were very similar to each other, consistent with findings of typical congenital achromatopsia. However, color-vision tests suggested that the brother had residual color discrimination, but the sister did not. The siblings had different full-field electroretinographic and spectral-sensitivity findings: residual cone functions were detected in only the brother, in agreement with his residual color vision. They also had different findings of retinal fundi and ocular refractions: the sister had bilaterally atrophic-appearing macular lesions and myopic errors. In contrast, the brother remains hyperopia and has exhibited no specific retinal findings until age 18 years. The causes why both complete and incomplete achromats occur in the siblings are uncertain but might be caused by modifying effects of sex-related genes or by environmental factors influencing certain gene regulations in cone photoreceptors.

Child↗