scholarly journals THE RENEWAL OF PROTEIN IN RETINAL RODS AND CONES

1968 ◽  
Vol 39 (1) ◽  
pp. 169-184 ◽  
Author(s):  
Richard W. Young ◽  
Bernard Droz
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Electron Microscope ◽  
Golgi Complex ◽  
Outer Segment ◽  
Photoreceptor Cells ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Utilization Of Protein ◽  
Low Levels

The renewal of protein in retinal rods and cones has been analyzed by quantitative electron microscope radioautography in adult frogs injected with a mixture of radioactive amino acids. Protein synthesis occurs predominantly in the ergastoplasm, localized in the myoid region of the photoreceptor cells. Much of the newly formed protein next flows through the Golgi complex. In rods, a large proportion of the protein then moves past the mitochondria of the ellipsoid segment, passes through the connecting cilium into the outer segment, and is there assembled into membranous discs at the base of that structure. Discs are formed at the rate of 36 per day in red rods and 25 per day in green rods at 22.5° C ambient temperature. In cones, a small proportion of the protein is similarly displaced to the outer segment. However, no new discs are formed. Instead, the protein becomes diffusely distributed throughout the cone outer segment. Low levels of radioactivity have been detected, shortly after injection, in the mitochondria, nucleus, and synaptic bodies of rods and cones. Nevertheless, in these organelles, the renewal process also appears to involve the utilization of protein formed in the ergastoplasm of the myoid.

scholarly journals Immunocytochemical localization of opsin in outer segments and Golgi zones of frog photoreceptor cells. An electron microscope analysis of cross-linked albumin-embedded retinas

1978 ◽  
Vol 77 (1) ◽  
pp. 196-210 ◽  
Author(s):  
DS Papermaster ◽  
BG Schneider ◽  
MA Zorn ◽  
JP Kraehenbuhl
Keyword(s):  
Electron Microscope ◽  
Outer Segment ◽  
Specific Binding ◽  
Photoreceptor Cells ◽  
Indirect Detection ◽  
Thin Sections ◽  
Rods And Cones ◽  
Outer Segments ◽  
Cell Structures ◽  
Cone Photopigments

Adult vertebrate retinal cells (rod and cones) continuously synthesize membrane proteins and transport them to the organelle specialized for photon capture, the outer segment. The cell structures involved in the synthesis of opsin have been identified by means of immunocytochemistry at the electron microscope level. Two indirect detection systems were used: (a) rabbit antibodies to frog opsin were localized with ferritin conjugated F(ab')2 of sheep antibodies to rabbit F(ab')2 and (b) sheep antibodies to cattle opsin were coupled to biotin and visualized by means of avidin-ferritin conjugates (AvF). The reagents were applied directly to the surface of thin sections of frog retinal tissues embedded in glutaraldehyde cross-linked bovine serum albumin (BSA). Specific binding of anti-opsin antibodies indicates that opsin is localized in the disks of rod outer segments (ROS), as expected, and in the Golgi zone of the rod cell inner segments. In addition, we observed quantitatively different labeling patterns of outer segments of rods and cones with each of the sera employed. These reactions may indicate immunological homology of rod and cone photopigments. Because these quantitiative variations of labeling density extend along the entire length of the outer segment, they also serve to identify the cell which has shed its disks into adjacent pigment ipithelial cell phagosomes.

scholarly journals IFT20 is required for opsin trafficking and photoreceptor outer segment development

2011 ◽  
Vol 22 (7) ◽  
pp. 921-930 ◽  
Author(s):  
Brian T. Keady ◽  
Yun Zheng Le ◽  
Gregory J. Pazour
Keyword(s):  
Cell Body ◽  
Golgi Complex ◽  
Outer Segment ◽  
Intraflagellar Transport ◽  
Photoreceptor Cells ◽  
High Rate ◽  
Cell Degeneration ◽  
Photoreceptor Outer Segment ◽  
Rods And Cones ◽  
Cone Development

The light-detecting outer segments of vertebrate photoreceptors are cilia. Like other cilia, all materials needed for assembly and maintenance are synthesized in the cell body and transported into the cilium. The highly elaborated nature of the outer segment and its high rate of turnover necessitate unusually high levels of transport into the cilium. In this work, we examine the role of the IFT20 subunit of the intraflagellar transport (IFT) particle in photoreceptor cells. IFT20 was deleted in developing cones by a cone-specific Cre and in mature rods and cones by a tamoxifen-activatable Cre. Loss of IFT20 during cone development leads to opsin accumulation in the inner segment even when the connecting cilium and outer segment are still intact. With time this causes cone cell degeneration. Similarly, deletion of IFT20 in mature rods causes rapid accumulation of rhodopsin in the cell body, where it is concentrated at the Golgi complex. We further show that IFT20, acting both as part of the IFT particle and independent of the particle, binds to rhodopsin and RG-opsin. Since IFT20 dynamically moves between the Golgi complex and the connecting cilium, the current work suggests that rhodopsin and opsins are cargo for IFT transport.

scholarly journals ELECTRON MICROSCOPE OBSERVATIONS ON SYNAPTIC VESICLES IN SYNAPSES OF THE RETINAL RODS AND CONES

1956 ◽  
Vol 2 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Eduardo De Robertis ◽  
Carlos M. Franchi
Keyword(s):  
Electron Microscope ◽  
Synaptic Vesicles ◽  
Sharp Decrease ◽  
Albino Rabbit ◽  
Synaptic Membrane ◽  
Complete Darkness ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Filamentous Material ◽  
Rod Cell

The submicroscopic organization of the rod and cone synapses of the albino rabbit has been investigated with the use of the electron microscope. The most common rod synapse consists of an enlarged expansion of the rod fiber (the so called spherule) into which the dendritic postsynaptic fiber of the bipolar cell penetrates and digitates. The membrane surrounding the terminal consists of a double layer, the external of which is interpreted as belonging to the intervening glial cells. The synaptic membrane has a pre- and a postsynaptic layer with a total thickness of 180 to 300 A. The presynaptic layer is frequently denser and is intimately associated with the adjacent synaptic vesicles. The synaptic membrane shows processes constituted by foldings of the presynaptic layer. The entire spherule is filled with synaptic vesicles varying in diameter between 200 and 650 A with a mean of 386 A. In addition, the spherule contains a few large vacuoles near the rod fiber, interpreted as endoplasmic reticulum, and a matrix in which with high resolution a fine filamentous material can be observed. The postsynaptic fiber is homogeneous and usually does not show synaptic vesicles. In animals maintained in complete darkness for 24 hours vesicles appear to accumulate near the synaptic membrane and its processes. After 9 days there is a sharp decrease in size of the synaptic vesicles. A special rod synapse in which the dendritic postsynaptic expansion penetrates directly into the rod cell body has been identified. In line with Cajal's classification this type of synapse could be considered as a somatodendritic one. The cone synapse has a much larger terminal with a more complex relationship with the postsynaptic fiber. However, the same components recognized in the rod synapse can be observed. In animals maintained for 9 days in complete darkness there is also a considerable diminution in size of the synaptic vesicles.

scholarly journals THE STRUCTURE AND CONCENTRATION OF SOLIDS IN PHOTORECEPTOR CELLS STUDIED BY REFRACTOMETRY AND INTERFERENCE MICROSCOPY

1957 ◽  
Vol 3 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Richard L. Sidman
Keyword(s):  
Photoreceptor Cells ◽  
Interference Microscopy ◽  
Refractive Indices ◽  
Rod Outer Segments ◽  
Vertebrate Species ◽  
Rods And Cones ◽  
Outer Segments ◽  
Retinal Rods ◽  
Cone Cells ◽  
Longitudinal Fiber

Fragments of freshly obtained retinas of several vertebrate species were studied by refractometry, with reference to the structure of the rods and cones. The findings allowed a reassessment of previous descriptions based mainly on fixed material. The refractometric method was used also to measure the refractice indices and to calculate the concentrations of solids and water in the various cell segments. The main quantitative data were confirmed by interference microscopy. When examined by the method of refractometry the outer segments of freshly prepared retinal rods appear homogeneous. Within a few minutes a single eccentric longitudinal fiber appears, and transverse striations may develop. These changes are attributed to imbibition of water and swelling in structures normally too small for detection by light microscopy. The central "core" of outer segments and the chromophobic disc between outer and inner segments appear to be artifacts resulting from shrinkage during dehydration. The fresh outer segments of cones, and the inner segments of rods and cones also are described and illustrated. The volumes, refractive indices, concentrations of solids, and wet and dry weights of various segments of the photoreceptor cells were tabulated. Rod outer segments of the different species vary more than 100-fold in volume and mass but all have concentrations of solids of 40 to 43 per cent. Cone outer segments contain only about 30 per cent solids. The myoids, paraboloids, and ellipsoids of the inner segments likewise have characteristic refractive indices and concentrations of solids. Some of the limitations and particular virtues of refractometry as a method for quantitative analysis of living cells are discussed in comparison with more conventional biochemical techniques. Also the shapes and refractive indices of the various segments of photoreceptor cells are considered in relation to the absorption and transmission of light. The Stiles-Crawford effect can be accounted for on the basis of the structure of cone cells.

scholarly journals Expression of the poly(A)-binding protein during development of Xenopus laevis.

1989 ◽  
Vol 9 (6) ◽  
pp. 2756-2760 ◽  
Author(s):  
B D Zelus ◽  
D H Giebelhaus ◽  
D W Eib ◽  
K A Kenner ◽  
R T Moon
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Xenopus Laevis ◽  
Fusion Protein ◽  
Outer Segment ◽  
Binding Protein ◽  
Polyclonal Antiserum ◽  
Xenopus Laevis Oocytes ◽  
Cdna Clones ◽  
Protein Encoding

We have isolated and sequenced cDNA clones encoding the poly(A)-binding protein of Xenopus laevis oocytes. Polyclonal antiserum was raised against a fusion protein encoding 185 amino acids of the Xenopus poly(A)-binding protein. This antiserum localizes the poly(A)-binding protein to subcellular sites associated with protein synthesis; in the retina, immunoreactive protein is detected in the synthetically active inner segment of the photoreceptor but not in the transductive outer segment. Transcripts encoding the poly(A)-binding protein are present in oocytes, although no protein is detected on protein blots. In contrast, the levels of both transcripts and protein increase in development, which correlates with the observed increase in total poly(A) during Xenopus embryogenesis (N. Sagata, K. Shiokawa, and K. Yamana, Dev. Biol. 77:431-448, 1980).

Topology of the Outer Segment Membranes of Retinal Rods and Cones Revealed by a Fluorescent Probe

Science ◽  
1974 ◽  
Vol 185 (4157) ◽  
pp. 1176-1179 ◽  
Author(s):  
S. Yoshikami ◽  
W. E. Robinson ◽  
W. A. Hagins
Keyword(s):  
Fluorescent Probe ◽  
Outer Segment ◽  
Rods And Cones ◽  
Retinal Rods

scholarly journals Glutathione Supplementation of Parenteral Nutrition Prevents Oxidative Stress and Sustains Protein Synthesis in Guinea Pig Model

Nutrients ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 2063 ◽  
Author(s):  
Guillaume Morin ◽  
Clémence Guiraut ◽  
Marisol Perez Marcogliese ◽  
Ibrahim Mohamed ◽  
Jean-Claude Lavoie
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Parenteral Nutrition ◽  
Lipid Emulsion ◽  
Gastrocnemius Muscle ◽  
Limited Growth ◽  
Low Levels ◽  
Guinea Pig Model

Peroxides contaminating parenteral nutrition (PN) limit the use of methionine as a precursor of cysteine. Thus, PN causes a cysteine deficiency, characterized by low levels of glutathione, the main molecule used in peroxide detoxification, and limited growth in individuals receiving long-term PN compared to the average population. We hypothesize that glutathione supplementation in PN can be used as a pro-cysteine that improves glutathione levels and protein synthesis and reduces oxidative stress caused by PN. One-month-old guinea pigs (7–8 per group) were used to compare glutathione-enriched to a non-enriched PN, animals on enteral nutrition were used as a reference. PN: Dextrose, amino acids (Primene), lipid emulsion (Intralipid), multivitamins, electrolytes; five-day infusion. Glutathione (GSH, GSSG, redox potential) and the incorporation of radioactive leucine into the protein fraction (protein synthesis index) were measured in the blood, lungs, liver, and gastrocnemius muscle. Data were analysed by ANOVA; p < 0.05 was considered significant. The addition of glutathione to PN prevented the PN-induced oxidative stress in the lungs and muscles and supported protein synthesis in liver and muscles. The results potentially support the recommendation to add glutathione to the PN and demonstrate that glutathione could act as a biologically available cysteine precursor.

scholarly journals CYTOPLASMIC GRANULE FORMATION IN MYELOCYTES

1966 ◽  
Vol 29 (2) ◽  
pp. 307-316 ◽  
Author(s):  
Martha E. Fedorko ◽  
James G. Hirsch
Keyword(s):  
Amino Acids ◽  
Bone Marrow ◽  
Electron Microscope ◽  
Golgi Complex ◽  
Time Sequence ◽  
Granule Formation ◽  
Initial Exposure ◽  
Cytoplasmic Granules

The intracellular flow of tritiated lysine as revealed by electron microscope radioautography was studied in heterophilic myelocytes of rabbit marrow. Label over the Golgi complex rose to a maximum of 37% of total cytoplasmic grains 30 min after initial exposure to the tracer and fell to 11% after 3 to 4 hr of incubation. Coincident with decrease in label over the Golgi complex, grain counts over granules rose to 32% after 3 to 4 hr. The time sequence of incorporation and flow of tritiated lysine and the per cent distribution of label was similar in bone marrow myelocytes under in vivo and in vitro conditions. The results demonstrate a function of the Golgi complex in incorporating or packaging certain basic amino acids or proteins into cytoplasmic granules of heterophilic myelocytes.

scholarly journals PROTEIN SYNTHESIS IN THE VISUAL CELLS OF THE HONEYBEE DRONE AS STUDIED WITH ELECTRON MICROSCOPE RADIOAUTOGRAPHY

1972 ◽  
Vol 55 (3) ◽  
pp. 595-605 ◽  
Author(s):  
Alain Perrelet
Keyword(s):  
Protein Synthesis ◽  
Electron Microscope ◽  
Single Injection ◽  
Visual Cell ◽  
Maximal Concentration ◽  
Cell Region ◽  
Photoreceptor Membrane ◽  
Visual Cells ◽  
Rods And Cones ◽  
Honeybee Drone

Protein synthesis was studied in the visual cells of an insect (honeybee drone, Apis mellifera) by electron microscope radioautography. After a single injection of tritiated leucine, the radioactivity first appears in the cytoplasm of the visual cell which contains ribosomes. Later, part of this radioactivity migrates to the rhabdome, the visual cell region which is specialized in light absorption. A maximal concentration of radioactivity is reached there 48 hr after the injection of leucine. This pattern of protein synthesis and transport resembles that described in vertebrate visual cells (rods and cones), where newly synthesized proteins have been shown to contribute to the renewal of the photoreceptor membrane.

scholarly journals FINE STRUCTURE OF THE PINEAL ORGANS OF THE ADULT FROG, RANA PIPIENS

1964 ◽  
Vol 22 (3) ◽  
pp. 653-674 ◽  
Author(s):  
Douglas E. Kelly ◽  
Stuart W. Smith
Keyword(s):  
Rana Pipiens ◽  
Photoreceptor Cells ◽  
Rods And Cones ◽  
Adult Frog ◽  
Outer Segments ◽  
Lateral Eye ◽  
Retinal Photoreceptors ◽  
Retinal Rods ◽  
Cytological Features ◽  
Pineal Photoreceptors

Frontal organs and epiphyses of the pineal system from the adult frog, Rana pipiens, were fixed in s-collidine-buffered osmium tetroxide, embedded in Epon 812, and examined by electron microscopy. Epiphyseal material was also fixed in a variety of ways and subjected to a series of cytochemical tests for light microscopy. An ultrastructure resembling that of lateral eye retina is confirmed in this species. Photoreceptor cells of the epiphysis and frontal organ display many cytological features similar to those of retinal rods and cones in the arrangement of their outer and inner segments and synaptic components. However, in these pineal organs the outer segments are disoriented relative to each other and may display a disarranged internal organization unlike normal retinal photoreceptors. Furthermore, other pineal outer segments often appear degenerate. Since immature stages in the development of new outer segments also appear to be present, adult pineal photoreceptors are probably engaged in a constant renewal of outer segment membranes. The evidence further suggests that macrophages are involved in phagocytosis of degenerated outer segments. Postulated photoreceptor activities and the possibility of secondary pineal functions, such as secretion, are discussed in view of current morphological and cytochemical findings.

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