Visual pigments before and after extraction from visual cells

1961 ◽  
Vol 154 (955) ◽  
pp. 250-266 ◽  
Keyword(s):  
Visual Pigments ◽  
Visual Cells ◽  
Before And After

Microspectrophotometry of visual pigments

1972 ◽  
Vol 5 (3) ◽  
pp. 349-393 ◽  
Author(s):  
Stanley D. Carlson
Keyword(s):  
Vitamin A ◽  
Conformational Change ◽  
Visual Pigments ◽  
Visual Cells ◽  
Rods And Cones ◽  
Outer Segments ◽  
Pigment Molecule ◽  
Receptor Membrane ◽  
Covalently Bonded ◽  
Membrane Changes

Visual pigments are embedded in the disc membranes of the outer segments of vertebrate rods and cones and in the microvilli of invertebrate visual cells. The pigment molecule in both is a most fascinating aggregate of known (the ubiquitous II-cis isomer of vitamin A1 or A2-aldehyde = retinal1 or 2; Hubbard & Wald, 1952) covalently bonded to the unknown (a protein termed opsin) (Anderson, Hoffman & Hall, 1971). This conjugated molecule is called rhodopsin or dehydrorhodopsin (porphryopsin) when the prosthetic portion is retinall or 2 respectively. So sensitive is this sterically hindered, bent and twisted molecule to light that absorption of one photon can initiate its isomerization to the all trans form. This conformational change is but one (but the best known) of the factors leading to receptor membrane changes ushering in the visual impulse.

scholarly journals Squid retinochrome.

1975 ◽  
Vol 65 (2) ◽  
pp. 235-251 ◽  
Author(s):  
L Sperling ◽  
R Hubbard
Keyword(s):  
Absorption Spectrum ◽  
Sodium Borohydride ◽  
Visual Pigments ◽  
Visual Cells

Retinochrome is a photosensitive pigment located primarily in the inner portions of the visual cells of cephalopods. Its absorption spectrum resembles that of rhodopsin, but its chromophore is all-trans retinal, which light isomerizes to 11-cis, the reverse of the situation in rhodopsin. The 11-cis photoproduct of retinochrome slowly reverts to retinochrome in the dark. The chromophoric site of retinochrome is more reactive than that of most visual pigments: (a) Hydroxylamine converts retinochrome in the dark to all-trans retinal oxime + retinochrome opsin. (by Sodium borohydride reduces it to N-retinyl opsin. (c) Lambda max of retinochrome shifts from 500 to 515 nm as the pH is raised from 6 to 10, with a loss of absorption above pH 8; meanwhile above this PH a second band appears at shorter wavelengths with lambda max 375 nm. These changes are reversible. (d) If retinochrome is incubated with all-trans 3-dehydroretinal (retinal2) in the dark, some 3-dehydroretinochrome (retinochrome2, lambda max about 515 nm) is formed. Conversely, when retinochrome2, made by adding all-trans retinal2 to bleached retinochrome or retinochrome opsin, is incubated in the dark with all-trans retinal some of it is converted to retinochrome. Retinal and 3-dehydroretinal therefore can replace each other as chromophores in the dark.

Visual cells and visual pigments of the river lamprey revisited

2020 ◽  
Vol 206 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Victor Govardovskii ◽  
Alexander Rotov ◽  
Luba Astakhova ◽  
Darya Nikolaeva ◽  
Michael Firsov
Keyword(s):  
Visual Pigments ◽  
Visual Cells ◽  
River Lamprey

Visual cells and visual pigments of the lamprey,Lampetra fluviatilis

1984 ◽  
Vol 154 (2) ◽  
pp. 279-286 ◽  
Author(s):  
V. I. Govardovskii ◽  
D. V. Lychakov
Keyword(s):  
Visual Pigments ◽  
Lampetra Fluviatilis ◽  
Visual Cells

Immunocytochemical reactivity of rod and cone visual pigments in the sturgeon retina

1992 ◽  
Vol 8 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Victor I. Govardovskii ◽  
Pál Röhlich ◽  
Ágoston Szél ◽  
Lida V. Zueva
Keyword(s):  
Visual Pigment ◽  
Staining Pattern ◽  
Visual Pigments ◽  
Immunocytochemical Staining ◽  
Type I ◽  
Type Ii ◽  
Neural Connections ◽  
Type Iii ◽  
Visual Cells ◽  
Cone Type

AbstractMicrospectrophotometry and immunocytochemistry with several antivisual pigment antibodies were used to study visual cells of the Siberian sturgeon, Acipenser baeri Brandt. The retina contained rods and three morphological types of cones: large cones with oil drops, small cones with oil drops, and cone-like cells without oil drops. Rods and cone-like drop-free cells were found to possess porphyropsin-549, while the large oil drop-bearing cones contained red-sensitive (P613), green-sensitive (P542), and blue-sensitive (P462) visual pigments. The immunocytochemical staining pattern with three antibodies to visual pigment proteins also revealed one visual pigment in rods and three visual pigments in cones. Rods were labeled with all three antibodies, while the majority of large cones (type I), presumably the red-sensitive ones, were negative with the polyclonal serum AO against bovine opsin. A less-frequently occurring large cone type (type II) was stained by all three antibodies including mAb COS-1 specific to middle-to-long-wave visual pigments in birds and mammals, and is thought to be green-sensitive. An even less-frequent large cone type (type III, probably the blue-sensitive one) did not bind COS-1. The small cones with oil droplets showed immunoreactivities similar to either type II or type III cones. The oil drop-free small photoreceptor exhibited a staining pattern identical with that of rods. These results indicate that the immunocytochemical approach can be used to reveal photoreceptor-specific neural connections in the sturgeon retina.

Deformation Replication

1970 ◽  
Vol 28 ◽  
pp. 280-281
Author(s):  
J. Temple Black
Keyword(s):  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Rake Face ◽  
Orthogonal Machining ◽  
Aluminum Chips ◽  
Before And After ◽  
Materials Used ◽  
Glass Knife ◽  
Very High

Tool materials used in ultramicrotomy are glass, developed by Latta and Hartmann (1) and diamond, introduced by Fernandez-Moran (2). While diamonds produce more good sections per knife edge than glass, they are expensive; require careful mounting and handling; and are time consuming to clean before and after usage, purchase from vendors (3-6 months waiting time), and regrind. Glass offers an easily accessible, inexpensive material ($0.04 per knife) with very high compressive strength (3) that can be employed in microtomy of metals (4) as well as biological materials. When the orthogonal machining process is being studied, glass offers additional advantages. Sections of metal or plastic can be dried down on the rake face, coated with Au-Pd, and examined directly in the SEM with no additional handling (5). Figure 1 shows aluminum chips microtomed with a 75° glass knife at a cutting speed of 1 mm/sec with a depth of cut of 1000 Å lying on the rake face of the knife.

The Clinical, Roentgenological and Morphological Effects of an Acute Exposure of Phosgene on the Lungs of Dogs

1971 ◽  
Vol 29 ◽  
pp. 236-237
Author(s):  
R. F. Bils ◽  
W. F. Diller ◽  
F. Huth
Keyword(s):  
Latent Period ◽  
Chemical Industry ◽  
Toxic Substance ◽  
Lung Edema ◽  
X Rays ◽  
Beagle Dogs ◽  
Male And Female ◽  
Morphological Alterations ◽  
Before And After ◽  
Electron Microscopes

Phosgene still plays an important role as a toxic substance in the chemical industry. Thiess (1968) recently reported observations on numerous cases of phosgene poisoning. A serious difficulty in the clinical handling of phosgene poisoning cases is a relatively long latent period, up to 12 hours, with no obvious signs of severity. At about 12 hours heavy lung edema appears suddenly, however changes can be seen in routine X-rays taken after only a few hours' exposure (Diller et al., 1969). This study was undertaken to correlate these early changes seen by the roengenologist with morphological alterations in the lungs seen in the'light and electron microscopes.Forty-two adult male and female Beagle dogs were selected for these exposure experiments. Treated animals were exposed to 94.5-107-5 ppm phosgene for 10 min. in a 15 m3 chamber. Roentgenograms were made of the thorax of each animal before and after exposure, up to 24 hrs.

Ultrastructure of Melanin Formation in Curvularia sp., Alternaria sp., and Drechslera Sorokiniana

1977 ◽  
Vol 35 ◽  
pp. 398-399
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
A. A. Bell
Keyword(s):  
Potassium Phosphate ◽  
Thielaviopsis Basicola ◽  
Wild Type ◽  
Potassium Phosphate Buffer ◽  
Transmission Microscopy ◽  
Electron Transmission ◽  
Melanin Formation ◽  
Before And After ◽  
Alternaria Sp ◽  
Electron Transmission Microscopy

(+)-Scytalone [3,4-dihydro-3,6,8-trihydroxy-l-(2Hj-naphthalenone] and 1,8-di- hydroxynaphthalene (DHN) have been proposed as intermediates of melanin synthesis in the fungi Verticillium dahliae (1, 2, 3, 4) and Thielaviopsis basicola (4, 5). Scytalone is enzymatically dehydrated by V. dahliae to 1,3,8-trihydroxynaphthalene which is then reduced to (-)-vermelone [(-)-3,4- dihydro-3,8-dihydroxy-1(2H)-naphthalenone]. Vermelone is subsequently dehydrated to DHN which is enzymatically polymerized to melanin.Melanin formation in Curvularia sp., Alternaria sp., and Drechslera soro- kiniana was examined by light and electron-transmission microscopy. Wild-type isolates of each fungus were compared with albino mutants before and after treatment with 1 mM scytalone or 0.1 mM DHN in 50 mM potassium phosphate buffer, pH 7.0. Both chemicals were converted to dark pigments in the walls of hyphae and conidia of the albino mutants. The darkened cells were similar in appearance to corresponding cells of the wild types under the light microscope.

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