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At least 19 recordsLinked to original sources
PubMed1975

Light dependence of osmium reactivity in mouse photoreceptor cells.

Mouse photoreceptor cells exhibit local accumulations of osmium deposits after prolonged osmic staining at slightly elevated temperatures. Deposits were evident along the membranes of outer segment lamellae, Golgi cisternae and vesicles, nuclear envelopes, and synaptic vesicles. Other membranes within the photoreceptor cells were unreactive. No osmium reactivity was seen in other cells of the retina except for osmiophilic outer segment material which had been phagocytized by the pigment epithelium. In the outer segments, inner segments, and synaptic regions of the photoreceptor cells, the amount of osmium reactivity was increased by light stimulation and decreased following extended dark adaptation. The possible significance of the localized osmium reactivity is discussed.

Animals↗
PubMed1991

Central projections of Limulus photoreceptor cells revealed by a photoreceptor-specific monoclonal antibody.

Studies of lateral, median, and ventral eyes of the chelicerate arthropod Limulus polyphemus (the common American horseshoe crab) are providing important basic information about mechanisms for information processing in the peripheral visual system and for the modulation of visual responses by light and circadian rhythms. The processing of visual information in Limulus brain is less well understood in part because the specific central projections of the various classes of visual neurons are not known. This study describes a mouse monoclonal antibody, 3C6A3, which binds to Limulus photoreceptor cell bodies, their axons, and terminals, but not to any other cell type in the central nervous system. This antibody, and intracellular injection of biocytin, are used to demonstrate the central projections of each type of photoreceptor. Our main conclusions are that: 1) the photoreceptors (retinular cells) of the lateral eye project only to the lamina; 2) the photoreceptors of the lateral rudimentary eye project to both the lamina and medulla; 3) the photoreceptors of the median ocellus project only to the ocellar ganglion; and 4) the photoreceptors of the rudimentary median (endoparietal) eye project to the ocellar ganglion and also into the optic tract. These results, along with previous studies, allow us to infer the projections of the secondary cells. The eccentric cells of the lateral eye project to the lamina, medulla, optic tract, and ocellar ganglion. The arhabdomeral cells of the median ocellus project through the ocellar ganglion and to optic tract to the medulla.

Afferent Pathways↗
PubMed1991

Establishment of photoreceptor cell polarity in culture revealed by mushroom lectin binding.

Differentiation of photoreceptor cells dissociated from chick embryo was investigated in a monolayer culture at low cell density and low serum concentration. The precursor cells were initially round and finally adopted the elongated and monopolar shape characteristic of such photoreceptor cells in vivo. They exhibited the primitive inner segment, and on its distal side showed a crest-like membrane expansion instead of the developed outer segment. The cell polarity of these cultured photoreceptor cells was examined using mushroom lectin, which has specific affinity for the D-galactose-beta(1,3)-N-acetylgalactosamine moiety. Rhodamine-labeled mushroom lectin uniformly initially stained the surface of early round photoreceptor cells, but with time the staining became restricted to the inner segment and its distal membrane expansion in all elongated photoreceptor cells at 12 days from the beginning of development. In semithin sections of 12-day-old chick embryo retina, mushroom lectin also stained the immature inner segment that had emerged at this stage. After hatching, light and electron microscopic observations revealed that the entire scleral surface of retinal plasma membranes as far as the outer limiting membrane, i.e. the inner and outer segments of all types of photoreceptor cells and also Müller cell processes, were stained with the mushroom lectin. These results clearly show that all photoreceptor cells can establish their inherent cell polarity even in culture, and that mushroom lectin is a valuable marker, for the investigation of photoreceptor cell polarity.

Animals↗
PubMed1992

mip causes hyperinnervation of a retinotopic map in Drosophila by excessive recruitment of R7 photoreceptor cells.

The two central photoreceptor neurons of the Drosophila eye, R7 and R8, form a retinotopic map in the optic lobe of the fly brain. We have developed a technique that allows us to visualize the projections of these neurons with high resolution. Using this technique, we have identified a new mutant, mip (more inner photoreceptors), in which this map shows a striking hyperinnervation. The extra terminals in the brain derive from an excessive recruitment of sevenless-independent R7 photoreceptor cells during eye development. The original R7, however, remains sevenless responsive. The behavior of this gene suggests that recruitment to the R7 pathway, and possibly to multiple programs in ommatidial assembly, is partially regulated by inhibition.

Alleles↗
PubMed1991

Decrease of opsin content in the developing rat photoreceptor cells by systemic administration of L-glutamate.

L-Glutamate, a putative photoreceptor cell neurotransmitter, causes thinning of the inner layers of the retina and has been used for preparing biologically fractionated photoreceptor cells. However, it is possible that absence of the inner retinal layers may affect the remaining retina, and/or glutamate may directly affect photoreceptor cells. We evaluated quantitatively the effects of L-glutamate on the developing photoreceptor cells by measuring the rod photoreceptor cell-specific protein, opsin. We purified rat rhodopsin and used it as the standard for measuring opsin content of rat retinas with competitive enzyme-linked immunosorbent assay. Various concentrations of glutamate were injected into 7-day-old rats, and the effects of the amino acid concentration on opsin expression were determined on postnatal day 14. Inner layers of the retina degenerated when 10 microliters or 15 microliters of 2.4 M glutamate/gram body weight was administered subcutaneously. Opsin content of these glutamate-treated retinas decreased significantly compared with control retinas. We administered glutamate to rats at various stages of development and determined the effects by light microscopy on postnatal day 14. The administration of glutamate resulted in no degeneration of the inner retina if injected on postnatal day 1 or 2, degeneration of the inner retina between day 3 to 7, and again, no degeneration after postnatal day 13. Opsin content decreased significantly when glutamate was administered between postnatal day 1 to 7, but not after day 13, the day the blood-retinal barrier seems to reach maturity. Our findings indicate that systemic administration of L-glutamate affects the expression of opsin in the developing rod photoreceptor cells.

Animals↗
PubMed1992

RPE conditioned medium stimulates photoreceptor cell survival, neurite outgrowth and differentiation in vitro.

In the present study we have investigated retinal pigment epithelium-photoreceptor cell interactions in vitro, and their contributions to photoreceptor cell survival and differentiation. Preparations enriched for intact photoreceptor cells from neonatal rat retina were grown in either serum-free medium supplemented with RPE-conditioned medium (RPE-CM) or in serum-free medium alone. A variety of substrate conditions were tested for the best neurite outgrowth. Cultures were monitored for 7 days by light and electron microscopy, as well as by opsin, vimentin and carbonic anhydrase-C immunocytochemistry. RPE-CM was found to stimulate both proliferation of flat cells and photoreceptor differentiation. The number of photoreceptors bearing neurites and their neurite length measurements showed significant differences between the RPE-CM group and the control group within 20 hr in culture. Elimination of contaminating flat cells by the addition of an antimitotic drug prevented photoreceptor cell morphological maturation; however, these cells survived as round cell bodies without processes for at least 10 days in the presence of RPE-CM and expressed opsin during this period. Conditioned medium from the flat-cell monolayers did not support photoreceptor differentiation or their survival. However, the presence of flat cells was a requisite to achieve any neurite outgrowth even in the presence of RPE-CM. In the absence of RPE-CM, neither photoreceptors nor flat cells survived or proliferated. Heat and trypsin treatment of the RPE-CM abolished all its growth-supporting activities which indicates its proteinaceous nature. This represents the first time in vitro that an RPE-derived factor(s) has been shown to be responsible for photoreceptor cell survival and differentiation.

Animals↗
PubMed1976

Optical guiding by photoreceptor cells.

The potential for any morphological part of a photoreceptor cell to function as an optical waveguide is determined 1) by the dimensionless parameter V as shown by Snyder (IEEE Trans., Microwave Theory Tech. 17: 1133, 1969) and by Snyder, Pask and Mitchell (J. Opt. Soc. Am. 63: 59, 1973), and 2) by the nature of the optical excitation for that part of the cell. The effects of these two factors are considered for the myoids and outer segments of vertebrate photoreceptor cells and for the crystalline tracts and rhabdomers of invertebrate photoreceptor cells. Examples of both guiding and nonguiding myoids, outer segments, rhabdomers and tracts are cited and some consequences for vision are analyzed.

Animals↗
PubMed1992

Photoreceptor cell types in the retina of various vertebrate species: immunocytochemistry with antibodies against rhodopsin and iodopsin.

Types of photoreceptor cells in the retinas of 36 species of vertebrates (5 classes, 14 orders) were investigated immunocytochemically with monoclonal antibodies against chicken iodopsin (Io-mAb) and antiserum against bovine rhodopsin (Rh-As). In mammals, Rh-As labeled the outer segments of some photoreceptor cells in striped squirrels (a diurnal mammal) and those of most photoreceptor cells in mice (a nocturnal mammal), while Io-mAb labeled any photoreceptor cells in either of them. In all species of birds studied, Io-mAb labeled the principal and accessory members of double cones and single cones with a red oil droplet. Rh-As labeled single cones with a yellow or clear oil droplet in addition to rods. In turtles, both Rh-As and Io-mAb labeled single cones with a red or clear oil droplet and the principal (with a yellow oil droplet) and accessory members of double cones. This suggests that the visual pigments in these cones of turtles have common epitopes with bovine rhodopsin and chicken iodopsin. In Japanese grass lizards, single cones with a yellow oil droplet and double cones were immunoreactive to both Rh-As and Io-mAb. In snakes, rods and cones could not be distinguished but both positively and negatively stained cells were observed by the use of each antibody. In geckos, however, all photoreceptor cells were immunonegative to Io-mAb. In all species studied in amphibians, Rh-As labeled rods but not cones. Neither rods nor cones reacted with Io-mAb. In fishes, almost all species studied had well developed cones, and some of these cones were labeled by Rh-As. However, Io-mAb labeled the outer segments of some cones only in loaches. Rh-As labeled photoreceptor cells in all species of fishes studied. Thus, Rh-As recognized the outer segments of rods in all species studied from fishes to mammals, whereas the epitope recognized by Io-mAb is conserved in some species of fishes, most species of reptiles and all species of birds studied.

Animals↗
PubMed1992

Retinal pigment epithelial cells play a central role in the conservation of docosahexaenoic acid by photoreceptor cells after shedding and phagocytosis.

The involvement of retinal pigment epithelial (RPE) cells in the recycling of docosahexaenoic acid (DHA), from phagocytized disc membranes back to the retina, was studied in frogs subsequent to injection of [3H]DHA via the dorsal lymph sac. Rod outer segments (ROS) gradually accumulated [3H]DHA as a dense, heavily labeled region that arrived at the distal tips by 28 days post-injection. Autoradiographic analysis at the time of maximal shedding and phagocytosis (1-2 hr after the onset of light) showed diffusely (before 28 days) and heavily (after 28 days) labeled phagosomes in RPE cells. Biochemical analysis of the [3H]DHA-containing lipids of discs that contribute to the labeling of RPE cells after phagocytosis was also performed. Between 27 and 34 days, when 12% of retinal [3H]DHA-lipids present in disc membranes are phagocytized by RPE cells, total retinal labeling remained unchanged. Taken together, these data suggest that the [3H]DHA of the densely labeled region of the ROS was recycled back to the photoreceptor cells only after it had reached the RPE cells following 28 days post-injection. We conclude that, following daily phagocytosis of ROS tips, RPE cells play a central role in the conservation and redelivery of ROS-derived DHA back to photoreceptor cells through the interphotoreceptor matrix.

Animals↗
PubMed1978

Limulus ventral eye. Physiological properties of photoreceptor cells in an organ culture medium.

Ventral photoreceptor cells bathed in an organ culture medium typically have resting potentials of -85 mV and membrane resistances of 35 Momega and, when dark-adapted, exhibit large potential fluctuations (LPFs) of 60 mV and small potential fluctuations (SPFs) of less than 30 mV. LPFs appear to be regenerative events triggered by SPFs, the well-known quantum bumps. In the dark, SPFs and LPFs occur spontaneously. At intensities near threshold, the rate of occurrence is directly proportional to light intensity, indicating that SPFs and LPFs are elicited by single photon events. At higher intensities, SPFs and LPFs sum to produce a receptor potential that is graded over approximately a 9-log-unit range of light intensity. Amplitude histograms of the discrete potential waves are bimodal, reflecting the SPF and LPF populations. Histograms of current waves are unimodal. SPFs and LPFs are insensitive to 1 microgram tetrodotoxin. I-V characteristics show initial inward currents of approximately 15 nA for voltage clamps to -40 mV and steady-state outward currents for all clamp potentials. Photoreceptor cells bathed in organ culture medium retain these properties for periods of at least 75 days.

Animals↗
PubMed1992

Synaptic plasticity in the rod terminals after partial photoreceptor cell loss in the heterozygous rds mutant mouse.

In the retina of mice heterozygous for the retinal degeneration slow gene (rds/+) the photoreceptor cells, both rods and cones, develop abnormal outer segments but establish normal synaptic contacts. The other retinal layers also show normal structural organization. Starting from the age of 2 months, a very slow loss of photoreceptor cells progresses throughout life. As a result, the photoreceptor cell population in the retina of the affected mice is reduced to less than half at the age of 9-18 months. In some of the surviving rod terminals during this period, an increase in the number of synaptic ribbons is recorded. At the same time, the profiles of processes originating from the second order neurons and participating in these synapses are also increased in number so that the multiple ribbons appear as centres of multiple synaptic sites. Morphometric measurements of the perimeter of the synaptic profiles in rod terminals show a significant increase in the rds/+ retina over that of the control retina. Observations based on serial electron microscopy indicate that multiple synaptic sites are developed while the number of the second order neuronal processes, entering the terminals, remains unchanged. The frequency of terminals with multiple synapses in the rds/+ retina increases with progressive photoreceptor cell loss. Similar changes do not occur in the terminals of the cones. It is postulated that loss of some rod photoreceptor cells within a group that is presynaptic to common bipolars or horizontal cells results in partial deafferentation which in turn stimulates the growth of the remaining synaptic elements. The possible compensatory effect and functional significance of such synaptic growth are discussed.

Aging↗
PubMed1991

Photoreceptor cell rescue at early and late RPE-cell transplantation periods during retinal disease in RCS dystrophic rats.

Normal retinal pigment epithelial (RPE) cells were transplanted into retinas of Royal College of Surgeons (RCS) dystrophic rats at different stages of the retinal disease process. RPE-cell transplantation at 10, 17 and 26 days resulted in rescue of photoreceptor cells, such that at 4 months the outer nuclear layer (ONL) was 8-10 cells in thickness as shown in retinas of age-matched control rats. Of these transplantation times, day 17 appeared to affect the best rescue of photoreceptor cells. Nongrafted retinas of 4 month-old RCS dystrophic rats exhibited scattered PRC's, most prevalent in the peripheral retina. In addition, a small, but significant increase in the ONL thickness was detected in vehicle-injected retinas (sham control) of 17 day-old RCS dystrophic rats at 2 months; however, at 3 months, the ONL thickness was reduced to control levels. A normal distribution of (Na+ + K+)-ATPase immunostain was demonstrated beneath grafted RPE cells in retinas of 4 month-old RCS dystrophic rats. Dense immunostaining was shown along rescued photoreceptor cell inner segments (IS), within the inner (IPL) and outer (OPL) plexiform layers and on plasmalemma of cell bodies in the inner nuclear layer (INL). In nongrafted retinas of age-matched RCS dystrophic rats, immunostaining for (Na+ + K+)-ATPase was observed only in the INL and IPL. Under RPE-cells transplants in retinas of 4 month-old RCS dystrophic rats, opsin immunostaining was detected along both rescued photoreceptor cell inner and outer (OS) segments and on plasmalemma of ONL cell bodies. However, immunostaining for opsin was restricted to a debris zone in nongrafted retinas of age-matched RCS dystrophic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Enzymic basis for cyclic GMP accumulation in degenerative photoreceptor cells of mouse retina.

The activities of guanylate cyclase, guanosine 3', 5'-monophosphate (cyclic GMP) phosphodiesterase and 5'-nucleotidase were measured during postnatal development in retinas of control and C3H/HeJ mice. In control retina, each of these enzyme activities increases in conjunction with photoreceptor cell differentiation and maturation. In C3H retina, guanylate cyclase and 5-nucleotidase activities increase with photoreceptor cell development and decrease with photoreceptor cell death. However, the activity of a class of cyclic GMP phosphodiesterase which distinguishes the photoreceptor cells of control mice and those of several other species is not demonstrable in retina of C3H mice at any age. It is suggested that the deficiency in cyclic GMP phosphodiesterase activity may account for the accumulation of cyclic GMP which has been shown to occur in the C3H photoreceptor cells before they degenerate.

Aging↗
PubMed1991

Optimal conditions for long-term photoreceptor cell rescue in RCS rats: the necessity for healthy RPE transplants.

Retinal pigment epithelial (RPE) cells from normal Long-Evans, healthy Royal College of Surgeons (RCS) pigmented congenic (rdy+p+) and RCS pigmented dystrophic rats were transplanted into retinas of RCS non-pigmented dystrophic rats at post-natal days 17 and 26 (P17 and P26). When examined at P60, rescued photoreceptor cells were found in all transplanted groups. In addition, a small, but significant increase in the outer nuclear layer (ONL) thickness was detected in retinas injected with vehicle (sham control); however, the ONL thickness was reduced to control levels by 3-5 months after injections in both the sham controls and the group grafted with RCS pigmented dystrophic RPE cells. Likewise, large volumes of vehicle were injected into the subretinal space resulting in no long lasting beneficial effects. Also, there was no significant difference between the ONL thickness in retinas grafted with RCS congenic RPE and those grafted with Long-Evans RPE. When donor RPE cells from Long-Evans rats at neonatal and adult stages were transplanted into P26 RCS hosts, photoreceptor cell rescue could be found; however, the younger RPE cells affected a better rescue than those derived from adult eyes. In addition, when RPE cells from 6- to 9-day-old Long-Evans rats were transplanted into retinas of RCS dystrophic rats at 10, 17 and 26 days, significant rescue of photoreceptor cells was observed. Of these transplantation times, day 17 appeared to affect the best rescue of photoreceptor cells up to 1 yr. In contrast, little or no rescue was observed in the retinas of those RCS dystrophic rats when RPE cell transplantation was performed at P38, P43 and P48. The photoreceptor cell rescue was also found to be dependent on the concentration of RPE cells injected, which was maximal at 60,000-120,000 cells microliters-1. These findings lead us to conclude that in order to affect long-term, up to 1 yr, rescue of photoreceptor cells in the RCS rat, young, healthy RPE cells are required and transplantation needs to be performed at early stages of the disease process.

Animals↗
PubMed1991

Rapid and selective uptake, metabolism, and cellular distribution of docosahexaenoic acid among rod and cone photoreceptor cells in the frog retina.

The uptake, metabolism, and cellular distribution of 3H-docosahexaenoic acid (3H-22:6) in the frog retina during in vitro incubation were studied. An initial diffuse labeling throughout the retina was detected by autoradiography and was followed by an active steady increase in labeled photoreceptor cells. After 6 hr of incubation, 92% of the label was concentrated in photoreceptor cells. Among these cells, 435-rods (green rods) labeled heavily and showed two to three times higher uptake than the 502-rods (red rods). Cone uptake labeling was the lowest, showing negligible labeling throughout the cytoplasm. However, oil droplets of the 575-cones actively concentrated 22:6. The high uptake of 3H-22:6 by photoreceptor cells was followed by its rapid esterification into phospholipids. After 6 hr of labeling, only 5% of the radioactivity in the retina was free 22:6, whereas 88% was esterified into phospholipids. The remaining 22:6 was distributed equally in triacylglycerols (TAGs) and diacylglycerols. When 3H-22:6 (0.11 microM) of high specific activity was used, early incubation times showed phosphatidylinositol (PI) labeling to be of the same order of magnitude or greater than that of phosphatidylcholine (PC) or phosphatidylethanolamine (PE). Although the amount of endogenous 22:6 esterified into PI accounted for less than 2% of the 22:6 in retinal phospholipids, 27% of 3H-22:6 labeling was recovered in this phospholipid. When 14C-22:6 at a final concentration of 70 microM was used, a different profile of lipid labeling was observed. Forty percent of the labeling remained in the free fatty acid pool, followed by TAG (24%), PC (14%), and PE (12%). PI showed the smallest increase in picomoles of 14C-22:6 incorporated, when compared with 3H-22:6. In conclusion, a selective and differential uptake of 3H-22:6 by photoreceptor cells is coupled to its active utilization for phospholipid biosynthesis, mainly that of PC, PE, and PI. The differential uptake of 3H-22:6 among photoreceptor cells may reflect involvement of this fatty acid in cell-specific functions.

Animals↗
PubMedDate not supplied

[Electron microscopic study of presumptive photoreceptor cells in the aboral organ of the ctenophore, Beroë cucumis].

Presumptive photoreceptor cells are located in the receptor epithelium of the aboral organ and exhibit some common morphological characters with flagellar photoreceptors of some invertebrates, as well as with photoreceptors of vertebrates. These cells are specifically distinguished by the presence of a special membrane structure in their epinuclear zone, this structure being the derivative of a cilium. Presumptive photoreceptor cells which have a short central projection and form in their basal part the synaptic contacts ("triads") with the adjacent nervous endings, may be classified as pseudosecondary receptor cells. Acetylcholinesterase was found in the synaptic regions. Cytoplasm of the presumptive photoreceptor cells is rich in granular vesicles which contain biogenic amines.

Animals↗
PubMed1976

[Embryonic pineal organ of Lacerta vivipara J. II. Electron microscopic study of 3H-5-hydroxytryptophan (3H-5-HTP) incorporation in the secretory rudimentary photoreceptor cells (SRP). The gradient of biochemical differentiation (author's transl)].

As the biosynthesis of indoleamines in Lacerta vivipara embryos from stage 36 to 40 is concerned, our ultrastructural radioautographic studies reveal a selective incorporation and metabolism of 3H-5-HTP in one of the two "sensory" cell types, the Secretory Rudimentary Photoreceptor cells (SRP). Specific radioautographic reactions are constantly for the most part located on the dense secretory granules which are stored in the basal processes of the SRP and originate in the Golgi complex. During ontogenesis, the amount of autoradiographically demonstrable tritiated indoleamines and the number of dense secretory granules increase at the same rate. The combination of electron microscopic and radioautographic studies shows that, during ontogenesis, a close relation exists between the cytological differentiation of the SRP and their capacity to synthesize and store indoleamines.

5-Hydroxytryptophan↗