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The Journal of Cell Biology Feb 1982Cone outer segments (OS) of the goldfish retina are diffusely labeled after intravitreal injection of [(3)H]fucose while rod OS remain unlabeled. By electron microscopic...
Cone outer segments (OS) of the goldfish retina are diffusely labeled after intravitreal injection of [(3)H]fucose while rod OS remain unlabeled. By electron microscopic radioautography, the OS of red- and blue-sensitive cones are heavily labeled while green- sensitive cone OS are lightly labeled. The time-course and pattern of OS labeling in all cone types from 30 min to 24 h resemble that of incorporation of other sugars into rhodopsin in rod OS. The nature of the cone OS-specific fucosylated component(s) was examined using biochemical techniques. Cone OS were prelabeled by intravitreal injection of [(3)H]fucose 24 h before sacrifice. Photoreceptor OS were isolated using a discontinuous sucrose density gradient and it was verified by electron microscopic radioautography that the only source of radioactivity in the preparations was cone OS. The different cone types could be recognized by the heaviness of labeling, characteristic membrane spacing, and 'staining' of green cone OS in vitro with horseradish peroxidase. After acid hydrolysis of prelabeled photoreceptor membranes, 90 percent of the counts were in the neutral sugar fraction which was analyzed by thin-layer chromatography. Approximately 70 percent of the radioactivity co-chromatographed with authentic fucose. SDS-PAGE/fluorography of prelabeled photoreceptor membranes revealed a single radioactive component that was lightly stained with coomassie blue and showed an apparent molecular weight of 33,000. This cone-derived band was separated from unlabeled rod opsin which was well stained and showed an apparent mol wt of 38,000. Isoelectric focusing under denaturing conditions produced two major and one minor band of radioactivity with isoelectric points of 8.2, 8.6, and 8.8 respectively. No radioactivity was found in association with a stained band corresponding in isoelectric point to that of bovine opsin (pl, 6.2). The fucosylated component was readily digested by pronase, indicating its protein nature. Washing of the isolated OS with isotonic and hypotonic buffers failed to extract major amounts of the radioactivity, suggesting that the fucosylated component is an integral membrane protein. The presence of a fucosylated protein thus represents a major difference between cone and rod OS in the goldfish and has enabled us to identify cone OS in preparations of isolated photoreceptor membranes and to demonstrate the separation of a cone-derived glycoprotein from rod opsin.
Topics: Animals; Cell Membrane; Fucose; Glycoproteins; Goldfish; Isoelectric Point; Microscopy, Electron; Molecular Weight; Photoreceptor Cells; Solubility
PubMed: 7061586
DOI: 10.1083/jcb.92.2.269 -
Experimental Eye Research Nov 2013Intact eyes of frog and mouse were studied by X-ray diffraction. Light-induced changes in the reflections from the rod outer segments (ROS) were recorded at a time... (Review)
Review
Intact eyes of frog and mouse were studied by X-ray diffraction. Light-induced changes in the reflections from the rod outer segments (ROS) were recorded at a time resolution of 0.1 and 1 s in frog and mouse, respectively. Lamellar diffraction from disk membranes was observed to the 10th order. In frog, the intensities of seven reflections were found to change significantly on 7-s intense illumination and the lamellar spacing, which was 30.4 nm in darkness, decreased by 0.5%. Time courses of changes in the intensity and the lamellar spacing were similar, saturating at about 7 s. Most of the intensity changes could be attributable to the spacing change. Thus, the effect of light on the electron density distribution was smaller than previously reported. The decrease in the lamellar spacing is attributed to changes in the intracellular ionic concentrations due to the blockage of the dark current. This may be a useful index to study the ionic movements in the cell. Mouse ROS's had a lamellar spacing larger than frog (32.4 nm). The structural changes after illumination were similar to those in frog ROS. This X-ray diffraction technique may be utilized to study functions of photoreceptor cells in transgenic mice and other animals.
Topics: Animals; Anura; Lighting; Mice; Photic Stimulation; Photoreceptor Cells
PubMed: 24095685
DOI: 10.1016/j.exer.2013.09.016 -
Journal of Neural Transplantation 1989Blindness from retinal disease is often the consequence of extensive damage to the photoreceptor cell population, while other cell types which form the neural retina are...
Blindness from retinal disease is often the consequence of extensive damage to the photoreceptor cell population, while other cell types which form the neural retina are relatively spared. In this setting, transplantation of photoreceptor cells could offer hope for the restoration of some degree of visual function. We tested the feasibility of this approach by transplanting immature retinal cells into the eyes of adult rats affected by late stage phototoxic retinopathy, which are almost totally devoid of photoreceptor cells. Dissociated neuroretinal cells from newborn rats were injected into the hosts' retinas. These cells were labelled with the fluorescent tracer Fast-blue for identification within the host eye. Survival time ranged from 3 to 100 post-transplantation days. Fundus examination of light-irradiated eyes showed pallor caused by a considerable reduction of the retino-choroidal vascular bed after light irradiation. Histologically the hosts exhibited decimation of the elements forming the outer layers throughout the entire retina. As visualized by light and electron microscopic procedures, we report the differentiation of clusters of transplanted photoreceptor cells, and the integration of these cells within the adjacent areas of the host retina. Fluorescence microscopy showed these clusters to be formed by fluorescently labelled cells developing in intimate contact with the unlabelled host retina. Electron microscopically it was possible to determine that these photoreceptors had established synaptic contacts. These observations indicate that successful transplantation of immature retinal cells is feasible into adult eyes that have suffered extensive retino-choroidal damage. These findings also support the concept that retinal transplantation is a procedure which may open new avenues into the study of retinal repair.
Topics: Animals; Animals, Newborn; Graft Survival; Light; Male; Microscopy, Electron; Photoreceptor Cells; Rats; Rats, Inbred F344; Retina; Retinal Ganglion Cells; Synapses
PubMed: 2519517
DOI: 10.1155/NP.1989.1 -
The Journal of Neuroscience : the... Oct 1992We have generated transgenic flies expressing R7 cell-specific opsins in the major class of photoreceptor cells of the Drosophila retina and characterized their spectral...
We have generated transgenic flies expressing R7 cell-specific opsins in the major class of photoreceptor cells of the Drosophila retina and characterized their spectral properties using high-resolution microspectrophotometry and sensitivity recordings. We show that the Rh3 and Rh4 opsin genes encode UV-sensitive opsins with similar spectral properties (lambda max = 345 nm and 375 nm), and that Rh3 corresponds to the R7p and R7marg class of visual pigments. We have also generated Rh3 and Rh4 isoform-specific antibodies and present an R7 cell map of the Drosophila retina. In a related set of experiments, we show that it is possible to coexpress two different visual pigments functionally in the same cell and produce photoreceptors that display the summed spectral response of the individual pigments. These findings open up the possibility of tuning an animal's visual behavior by targeted expression of combinations of opsin genes to selective types of photoreceptors.
Topics: Animals; Animals, Genetically Modified; Color Perception; Drosophila melanogaster; Photoreceptor Cells; Promoter Regions, Genetic; Rhodopsin; Rod Opsins
PubMed: 1403087
DOI: 10.1523/JNEUROSCI.12-10-03862.1992 -
Trends in Neurosciences Feb 1996Over the past decade and a half, there have been great advances in our understanding of how light is transduced into electrical signals by the retinal rod and cone... (Review)
Review
Over the past decade and a half, there have been great advances in our understanding of how light is transduced into electrical signals by the retinal rod and cone photoreceptors in vertebrates. One essential feature of these sensory neurons is their ability to adapt to background illumination, which allows them to function over a broad range of light intensities. This adaptation appears to arise mostly from negative feedback on phototransduction that is mediated by calcium ions. Recent work has suggested that this feedback is fairly complex, and involves several pathways directed at different components of phototransduction. From direct measurements of these feedback pathways in rods, it is possible to evaluate their relative contributions to the overall sensitivity of the cell. At the same time, these feedback mechanisms, as currently known, appear to be sufficient for explaining the change in sensitivity of rods during adaptation to light.
Topics: Animals; Calcium; Humans; Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Vertebrates
PubMed: 8820871
DOI: 10.1016/0166-2236(96)89624-x -
Cell Oct 1995
Review
Topics: Animals; Neuromuscular Junction; Photoreceptor Cells; Ranidae; Synapses; Synaptic Transmission
PubMed: 7585936
DOI: 10.1016/0092-8674(95)90160-4 -
Current Biology : CB Dec 1995
Review
Topics: Cryptochromes; Drosophila Proteins; Eye Proteins; Flavoproteins; Genes, Plant; Light; Photoreceptor Cells; Photoreceptor Cells, Invertebrate; Plant Proteins; Receptors, G-Protein-Coupled; Signal Transduction
PubMed: 8749382
DOI: 10.1016/s0960-9822(95)00267-3 -
Toxicology and Applied Pharmacology Dec 2013In human trials certain heat shock protein 90 (Hsp90) inhibitors, including 17-DMAG and NVP-AUY922, have caused visual disorders indicative of retinal dysfunction;...
In human trials certain heat shock protein 90 (Hsp90) inhibitors, including 17-DMAG and NVP-AUY922, have caused visual disorders indicative of retinal dysfunction; others such as 17-AAG and ganetespib have not. To understand these safety profile differences we evaluated histopathological changes and exposure profiles of four Hsp90 inhibitors, with or without clinical reports of adverse ocular effects, using a rat retinal model. Retinal morphology, Hsp70 expression (a surrogate marker of Hsp90 inhibition), apoptotic induction and pharmacokinetic drug exposure analysis were examined in rats treated with the ansamycins 17-DMAG and 17-AAG, or with the second-generation compounds NVP-AUY922 and ganetespib. Both 17-DMAG and NVP-AUY922 induced strong yet restricted retinal Hsp70 up-regulation and promoted marked photoreceptor cell death 24h after the final dose. In contrast, neither 17-AAG nor ganetespib elicited photoreceptor injury. When the relationship between drug distribution and photoreceptor degeneration was examined, 17-DMAG and NVP-AUY922 showed substantial retinal accumulation, with high retina/plasma (R/P) ratios and slow elimination rates, such that 51% of 17-DMAG and 65% of NVP-AUY922 present at 30 min post-injection were retained in the retina 6h post-dose. For 17-AAG and ganetespib, retinal elimination was rapid (90% and 70% of drugs eliminated from the retina at 6h, respectively) which correlated with lower R/P ratios. These findings indicate that prolonged inhibition of Hsp90 activity in the eye results in photoreceptor cell death. Moreover, the results suggest that the retina/plasma exposure ratio and retinal elimination rate profiles of Hsp90 inhibitors, irrespective of their chemical class, may predict for ocular toxicity potential.
Topics: Animals; Benzoquinones; Disease Models, Animal; Dose-Response Relationship, Drug; HSP90 Heat-Shock Proteins; Lactams, Macrocyclic; Male; Photoreceptor Cells; Predictive Value of Tests; Rats; Rats, Long-Evans; Rats, Sprague-Dawley; Retinal Degeneration
PubMed: 24090817
DOI: 10.1016/j.taap.2013.09.018 -
FEBS Letters Dec 1987We examined the intracellular distribution of three proteins involved in the cyclic GMP cascade of visual transduction; cGMP phosphodiesterase, the alpha-subunit of...
We examined the intracellular distribution of three proteins involved in the cyclic GMP cascade of visual transduction; cGMP phosphodiesterase, the alpha-subunit of G-protein and arrestin. In adult rats, light-induced changes in the amounts of G and arrestin in the photoreceptor cell outer segments were observed both by polyacrylamide gel analysis of purified ROS and by immunocytochemical localization on retinal sections. In dark conditions, G was concentrated in the outer segments of photoreceptor cells while in the light G alpha was seen in the inner segments and the outer nuclear layer. Arrestin had the opposite distribution, appearing in the inner segments and outer nuclear layer under dark conditions and in the ROS under light conditions. In contrast, PDE, the enzyme which is activated by G and inhibited by arrestin showed no light-stimulated movement. In both light- and dark-adapted retinas, PDE was localized primarily in the outer segments of the photoreceptor cells.
Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Antigens; Arrestin; Dark Adaptation; Electrophoresis, Polyacrylamide Gel; Eye Proteins; GTP-Binding Proteins; Immunoenzyme Techniques; Light; Male; Photoreceptor Cells; Rats; Rats, Inbred Strains; Rod Cell Outer Segment
PubMed: 2826235
DOI: 10.1016/0014-5793(87)81144-4 -
The British Journal of Ophthalmology Aug 2004
Topics: Animals; Copepoda; Photoreceptor Cells; Predatory Behavior; Retina; Visual Perception
PubMed: 15295838
DOI: 10.1136/bjo.2004.049502