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The Journal of Physiology Dec 19731. Membrane current was derived from simultaneous measurements of interstitial ;dark' voltages and conductivities along the radial axis of frog photoreceptor cells....
1. Membrane current was derived from simultaneous measurements of interstitial ;dark' voltages and conductivities along the radial axis of frog photoreceptor cells. Membrane current was subsequently resolved into its component ionic currents or fluxes by means of ionic substitution and by the use of inhibitors of active transport.2. The plasma membrane of the frog rod outer segment was found to be permeable to Na(+) and Cl(-), with a ratio of Na(+) to K(+) permeabilities higher than that found in most neuronal cells. A net inward flux of 1.5 x 10(8) Na(+)/sec.rod flows across the outer segment plasma membrane in the dark.3. The proximal portion of the rod receptor, extending from the proximal region of the inner segment to the synaptic terminal, is mainly permeable to K(+), although some degree of Na(+) permeability is also presumed.4. A hyperpolarizing electrogenic Na pump was localized to the base of the outer segment and inner segment of the cell. The pump transfers at least 10(8) charges/sec out of the cell at this level, the pump current dividing and re-entering the cell at both the outer segment and proximal portion of the photoreceptor including the synaptic terminal.5. These findings have been incorporated into an ionic model of the photoreceptor, and its implications for cellular functioning considered.
Topics: Animals; Anura; Biological Transport, Active; Cell Membrane; Chlorides; Dark Adaptation; Membrane Potentials; Photoreceptor Cells; Potassium; Sodium
PubMed: 4763993
DOI: 10.1113/jphysiol.1973.sp010390 -
Methods in Cell Biology 2010In recent years, studies of zebrafish rod and cone photoreceptors have yielded novel insights into the differentiation of distinct photoreceptor cell types and the...
In recent years, studies of zebrafish rod and cone photoreceptors have yielded novel insights into the differentiation of distinct photoreceptor cell types and the mechanisms guiding photoreceptor regeneration following cell death, and they have provided models of human retinal degeneration. These studies were facilitated by the use of transgenic zebrafish expressing fluorescent reporter genes under the control of various cell-specific promoters. Improvements in transgenesis techniques (e.g., Tol2 transposition), the availability of numerous fluorescent reporter genes with different localization properties, and the ability to generate transgenes via recombineering (e.g., Gateway technology) have enabled researchers to quickly develop transgenic lines that improve our understanding of the causes of human blindness and ways to mitigate its effects.
Topics: Animals; Animals, Genetically Modified; Gene Transfer Techniques; Green Fluorescent Proteins; Photoreceptor Cells; Retina; Zebrafish
PubMed: 21111218
DOI: 10.1016/B978-0-12-384892-5.00007-4 -
Journal of Pharmacological Sciences Jul 2017Carotenoids, in particular astaxanthin, possess potent antioxidant capabilities. Astaxanthin also induces NF-E2-related factor 2 (Nrf2), which plays a major regulatory...
Carotenoids, in particular astaxanthin, possess potent antioxidant capabilities. Astaxanthin also induces NF-E2-related factor 2 (Nrf2), which plays a major regulatory role in the antioxidative response. However, little is known whether the carotenoid, by-products of astaxanthin, activate Nrf2. Toward this end, we screened eight astaxanthin analogs for Nrf2 activation in murine photoreceptor cell line, 661 W, by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). In addition, we monitored cell death in 661 W cells pretreated with astaxanthin analogs or only pretreated for 6 h with astaxanthin analogs and then exposed to light. Furthermore, we quantified the reactive oxygen species (ROS) production. Cell death was quantified after light exposure by nuclear staining. Nrf2-controlled genes Ho-1, Nqo-1, and Gclm by qRT-PCR and Nrf2 in the nucleus were upregulated in 661 W cells exposed astaxanthin, adonixanthin, echinenone, and lycopene. Moreover, astaxanthin, adonixanthin, echinenone, β-carotene, adonirubin, and lycopene, but not canthaxanthin, suppressed ROS production and protected cells against light-induced damage. Moreover, pretreatment with adonixanthin or lycopene only before light exposure protected against light-induced cell damage and Nrf2 silencing canceled these effects. These findings indicate that the more potent astaxanthin analogs, adonixanthin and lycopene, protect against light-induced cell damage through not only an anti-oxidative response but also through Nrf2 activation.
Topics: Animals; Antioxidants; Carotenoids; Cell Death; Cell Line; Gene Silencing; Light; Lycopene; Mice; NF-E2-Related Factor 2; Photoreceptor Cells; Reactive Oxygen Species
PubMed: 28689962
DOI: 10.1016/j.jphs.2017.05.011 -
International Journal of Molecular... Dec 2021Green rods (GRs) represent a unique type of photoreceptor to be found in the retinas of anuran amphibians. These cells harbor a cone-specific blue-sensitive visual...
Green rods (GRs) represent a unique type of photoreceptor to be found in the retinas of anuran amphibians. These cells harbor a cone-specific blue-sensitive visual pigment but exhibit morphology of the outer segment typical for classic red rods (RRs), which makes them a perspective model object for studying cone-rod transmutation. In the present study, we performed detailed electrophysiological examination of the light sensitivity, response kinetics and parameters of discrete and continuous dark noise in GRs of the two anuran species: cane toad and marsh frog. Our results confirm that anuran GRs are highly specialized nocturnal vision receptors. Moreover, their rate of phototransduction quenching appeared to be about two-times slower than in RRs, which makes them even more efficient single photon detectors. The operating intensity ranges for two rod types widely overlap supposedly allowing amphibians to discriminate colors in the scotopic region. Unexpectedly for typical cone pigments but in line with some previous reports, the spontaneous isomerization rate of the GR visual pigment was found to be the same as for rhodopsin of RRs. Thus, our results expand the knowledge on anuran GRs and show that these are even more specialized single photon catchers than RRs, which allows us to assign them a status of "super-rods".
Topics: Animals; Anura; Isomerism; Kinetics; Light; Light Signal Transduction; Night Vision; Photoreceptor Cells, Vertebrate; Retina; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells; Rhodopsin; Rod Opsins; Vision, Ocular
PubMed: 34948198
DOI: 10.3390/ijms222413400 -
Stem Cells (Dayton, Ohio) Jul 2012Retinal degeneration is a leading cause of irreversible blindness in the developed world. Differentiation of retinal cells, including photoreceptors, from both mouse and...
Retinal degeneration is a leading cause of irreversible blindness in the developed world. Differentiation of retinal cells, including photoreceptors, from both mouse and human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), potentially provide a renewable source of cells for retinal transplantation. Previously, we have shown both the functional integration of transplanted rod photoreceptor precursors, isolated from the postnatal retina, in the adult murine retina, and photoreceptor cell generation by stepwise treatment of ESCs with defined factors. In this study, we assessed the extent to which this protocol recapitulates retinal development and also evaluated differentiation and integration of ESC-derived retinal cells following transplantation using our established procedures. Optimized retinal differentiation via isolation of Rax.GFP retinal progenitors recreated a retinal niche and increased the yield of Crx(+) and Rhodopsin(+) photoreceptors. Rod birth peaked at day 20 of culture and expression of the early photoreceptor markers Crx and Nrl increased until day 28. Nrl levels were low in ESC-derived populations compared with developing retinae. Transplantation of early stage retinal cultures produced large tumors, which were avoided by prolonged retinal differentiation (up to day 28) prior to transplantation. Integrated mature photoreceptors were not observed in the adult retina, even when more than 60% of transplanted ESC-derived cells expressed Crx. We conclude that exclusion of proliferative cells from ESC-derived cultures is essential for effective transplantation. Despite showing expression profiles characteristic of immature photoreceptors, the ESC-derived precursors generated using this protocol did not display transplantation competence equivalent to precursors from the postnatal retina.
Topics: Animals; Cells, Cultured; Embryonic Stem Cells; Flow Cytometry; Immunohistochemistry; Mice; Photoreceptor Cells; Real-Time Polymerase Chain Reaction; Retina; Reverse Transcriptase Polymerase Chain Reaction; Stem Cell Transplantation
PubMed: 22570183
DOI: 10.1002/stem.1123 -
Journal of Nippon Medical School =... 2018Photoreceptors differentiated from somatic cells are a useful tool for transplantation and drug screening. We previously showed that photosensitive cells are...
BACKGROUND
Photoreceptors differentiated from somatic cells are a useful tool for transplantation and drug screening. We previously showed that photosensitive cells are differentiated from human fibroblasts by direct reprogramming. In induced pluripotent stem (iPS) cells or embryonic stem (ES) cells, the properties of differentiated cells differ among the source of cell lines. However, whether or not the properties of the photosensitive cells produced by direct reprogramming are controlled by the origin of the cell line remains unknown.
METHODS
We compared the morphological and physiological properties of photosensitive cells induced by two fibroblast cell lines.
RESULTS
The differentiated cells had larger somas and more primary processes than the non-infected cells in both cell lines. The degree of morphological change was statistically different between the two cell lines. In addition, physiological responses to light differed between the two cell lines. An outward current (photoreceptor-like response) was observed in both cell lines, while an inward current (intrinsically photosensitive retinal ganglion cell-like response) was observed only in one cell line under light stimulation.
CONCLUSIONS
These results suggest that photosensitive cells produced from different cell lines by direct reprogramming might express different phenotypes.
Topics: Cell Differentiation; Cell Line; Cellular Reprogramming Techniques; Dermis; Fibroblasts; Humans; Phenotype; Photoreceptor Cells
PubMed: 29731494
DOI: 10.1272/jnms.2018_85-17 -
Investigative Ophthalmology & Visual... Sep 2005To assess cone photoreceptor and cone-mediated postreceptoral retinal function in infants.
PURPOSE
To assess cone photoreceptor and cone-mediated postreceptoral retinal function in infants.
METHODS
ERG responses to a 1.8-log unit range of long-wavelength flashes on a white, rod-saturating background were recorded in 4-week-old (n = 22) and 10-week-old (n = 28) infants and control adults and children, 8 to 40 years of age (n = 13). A model of the activation of cone phototransduction was fit to the a-waves. Sensitivity (S(CONE)) and saturated-response amplitude (R(CONE)) were calculated. The amplitude and implicit time of the b-wave were examined as a function of stimulus intensity. The cone photoresponse parameters were compared to the rod photoresponse parameters (S(ROD) and R(ROD)) in the same subjects.
RESULTS
S(CONE) and R(CONE) in infants were significantly smaller than in the mature control subjects. The mean S(CONE) was 64% and 68%, and the mean R(CONE) was 63% and 72% in 4- and 10-week-olds, respectively. The mean rod photoresponse parameters were considerably less mature, as the mean S(ROD) was 35% and 46%, and the mean R(ROD) was 39% and 43% of mature values at 4 and 10 weeks. The b-wave stimulus-response functions in the 4- and 10-week-old infants did not show the photopic hill that was characteristic of the children's and adults' photopic b-waves.
CONCLUSIONS
Peripheral cone function is relatively more mature than rod function in young infants. The lack of a photopic hill is hypothesized to result from immaturity in the relative contributions of ON and OFF bipolar cell responses.
Topics: Adolescent; Adult; Aging; Child; Electroretinography; Humans; Infant; Ocular Physiological Phenomena; Photic Stimulation; Retinal Cone Photoreceptor Cells; Retinal Rod Photoreceptor Cells
PubMed: 16123452
DOI: 10.1167/iovs.05-0382 -
Brain Research May 1997Immunocytochemical methods were used to visualize carnosine (beta-alanyl-L-histidine)-like immunoreactivity (-LI) in the frog retina and to compare its localization with...
Immunocytochemical methods were used to visualize carnosine (beta-alanyl-L-histidine)-like immunoreactivity (-LI) in the frog retina and to compare its localization with that of glutamate. Carnosine-LI was conspicuous in photoreceptors and bipolar cells. The axon terminals of labelled bipolar cells formed five bands in the inner plexiform layer. A few presumed amacrine and ganglion cells, as well as Müller cell endfeet, were also labelled. Post-embedding immunocytochemistry revealed particularly high levels of glutamate-LI in the synaptic axon terminals of bipolar cells, with a mean gold particle density 5 x higher than that of amacrine cells. Photoreceptor terminals were also labelled, but with a labelling intensity about half that of bipolar cells. Labelling of serial semithin sections showed co-localization of carnosine and glutamate in photoreceptors and bipolar cells. These findings are consistent with the notion that glutamate is the neurotransmitter of neuronal elements that transfer information vertically through the retina. We propose that carnosine may modulate GABA and/or glutamate receptors by virtue of its ability to chelate Zn2+ and other ions.
Topics: Animals; Carnosine; Glutamic Acid; Immunohistochemistry; Microscopy, Electron; Photoreceptor Cells; Rana esculenta; Retina
PubMed: 9203543
DOI: 10.1016/s0006-8993(97)00211-4 -
The Journal of Neuroscience : the... Jan 1988Rod photoreceptors have been isolated from the adult rabbit retina using enzymatic and mechanical dissociation procedures; their fine structure, synaptic activity, and...
Rod photoreceptors have been isolated from the adult rabbit retina using enzymatic and mechanical dissociation procedures; their fine structure, synaptic activity, and long-term viability were examined using conventional electron-microscopic, quick-freezing, and cell culture techniques. Freshly dissociated photoreceptors were well-preserved compared to their counterparts in the intact retina. About half of the cells, however, exhibited broad continuity between inner and outer segments. Quick-frozen, freeze-substituted rods differed from chemically fixed cells in 3 respects: (1) there was an increased amount of granular matrix in the cytoplasm, mitochondria, and rough endoplasmic reticulum; (2) branching and anastomosing profiles of smooth endoplasmic reticulum had disappeared from the inner segment; and (3) the number of synaptic vesicles within the spherule was highly variable, in some cases leaving synaptic ribbons completely denuded of their halo of vesicles. Light-adapted, solitary rod cells continued to be synaptically active: their endings were capable of endocytosis when placed in the dark in the presence of extracellular ferritin and tracer was incorporated into vesicles and vacuoles; this uptake was much reduced when the cells were incubated with the tracer in the light. Thus, synaptic vesicle regeneration was stimulated in the dark, suggesting that vesicles underwent exocytosis in the dark. Isolated rod cells adhered poorly to most standard substrates; without proper adhesion, cells deteriorated in 2-4 hr. However, photoreceptors did adhere to glutaraldehyde-fixed Vitrogen gels and could be maintained for over 48 hr on this substrate if kept in a complete medium at 22 degrees C. In contrast, Müller cells adhered quickly to a laminin substrate with their endfoot processes. The differential adhesion properties of Müller and photoreceptor cells may be useful in obtaining pure populations of glial cells or neurons from the adult mammalian retina.
Topics: Animals; Cell Survival; Cells, Cultured; Ferritins; Freezing; Microscopy, Electron; Photoreceptor Cells; Rabbits; Time Factors
PubMed: 3339415
DOI: 10.1523/JNEUROSCI.08-01-00320.1988 -
The Journal of Biological Chemistry May 1994
Comparative Study Review
Topics: Animals; Antigens; Arrestin; Calcium; Cell Membrane; Cyclic GMP; Eye Proteins; Inositol 1,4,5-Trisphosphate; Invertebrates; Light; Phosphodiesterase Inhibitors; Phosphorylation; Photoreceptor Cells; Photoreceptor Cells, Invertebrate; Protein Kinase C; Retinal Cone Photoreceptor Cells; Rhodopsin; Rod Cell Outer Segment; Rod Opsins; Signal Transduction; Vertebrates
PubMed: 8182033
DOI: No ID Found