1,465 Result(s)
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English
Biochemistry, general
Neurosciences
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Chapter
Conference Paper
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Chapter and Conference Paper
Metarhodopsin III
The photic isomerization of rhodopsin is followed by a number of dark reactions (1) some of which are also photosensitive (2). Information is available on their various half- lifes, which, as expected, vary wi...
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Chapter and Conference Paper
Interrelations of Visual Pigments and “Vitamins A” in Fish and Amphibia
In frogs and fish, although perhaps not in mammals (1, 2), the pigment epithelium plays a decisive role in visual pigment regeneration (see Baumann, 3, for review). This is illustrated in Fig. 1 for Rana clamitan...
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Chapter and Conference Paper
Active Site and Enzymological Studies on the Components of the Visual Cycle
Developments in the biochemistry of vision over the last quarter century may be summarized by the equations 1–3 of Scheme 1. The first reaction in the Scheme involves the combination in a dark reaction of the ...
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Chapter and Conference Paper
Behavior of Rhodopsin and Metarhodopsin in Isolated Rhabdoms of Crabs and Lobster
The photoreceptor organelles — the rhabdoms — of decapod Crustacea are elongate structures consisting of interleaved layers of microvilli from seven or eight retinular cells (1,2,3). When the eyes are broken o...
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Chapter and Conference Paper
Biochemical Properties of Retinochrome
The cephalopod retina has two kinds of photosensitive pigments. These pigments have been examined in various squids and octopi (1–4), and are called rhodopsin and retinochrome(5). Rhodopsin is present in the o...
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Chapter and Conference Paper
The Photopigments in an Insect Retina
Colour vision is not an exclusive property of vertebrates. Also insects can discriminate wavelengths. The best known example is the honeybee, as shown by training experiments (1) and electrophysiological recor...
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Chapter and Conference Paper
Rod Dark-Adaptation and Visual Pigment Photoproducts
Measurement of the dark-adaptation of single retinal units (ganglion cells) in the frog has shown that the rod branch of the dark-adaptation curve after bleaching small amounts of rhodopsin is approximately ex...
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Chapter and Conference Paper
Adaptation Properties of Intracellularly Recorded Gekko Photoreceptor Potentials
Over the past century, a comprehensive description of the phenomena of visual adaptation in vertebrates has been achieved. More recently, much interest has focused on the identification of the cellular locus o...
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Chapter and Conference Paper
Excitation and Adaptation in the Cephalopod Retina: An Equivalent Circuit Model
There are three basic questions in photoreceptor physiology that have not yet been fully answered: the problems of latency, excitation and adaptation. Any model of a photoreceptor cell, if it is to be useful, ...
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Chapter and Conference Paper
Visual Pigments and Photoreceptor Physiology
We who work with the visual pigments are fortunate in our field. It offers unique opportunities to engage, and we hope perhaps to solve, some of the central problems of present-day biology. It projects also in...
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Chapter and Conference Paper
Photovoltages and Dark Voltage Gradients Across Receptor Layer of Dark-Adapted Rat Retina
Saline filled micropipette electrodes have been used to measure photovoltages and dark voltages across the receptor layers of isolated, incubated rat retinas. The general techniques employed were similar to th...
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Chapter and Conference Paper
Control of the Dark Current in Vertebrate Rods and Cones
The excitatory process in a vertebrate rod or cone is known to begin with photochemical cis-trans isomerization of a carotenoid chromophore and to result in transient change in the cell’s membrane potential, t...
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Chapter and Conference Paper
Conformations of 11-cis Retinal
Isoprenic polyenes have two different kinds of double bonds depending on the nature of the substituents, X and X′: The question if compounds of...
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Chapter and Conference Paper
The Internal Transmitter Model for Visual Excitation: Some Quantitative Implications
Fuortes and his co-workers (1–3) have suggested that rhodopsin, in both vertebrate and invertebrate photoreceptors, may excite the cell by releasing a transmitter substance which diffuses internally to other r...
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Chapter and Conference Paper
Chromophore Migration after Illumination of Rhodopsin
The main facts known about the fate of the chromophore of rhodopsin after illumination can be summarized as follows. The chromophore in native rhodopsin, 11-cis retinaldehyde, is bound to an amino group by mea...
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Chapter and Conference Paper
Ultrastructure of the Photoreceptors of the Bovine Retina
The bovine retina is the tissue studied in greatest detail by the vision biochemist but from the standpoint of gross morphology and ultrastructure it has been neglected. From the present observations of the bo...
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Chapter and Conference Paper
Photoselection and Linear Dichroism of Retinal Isomers and Visual Pigments
It has been known for about ten years that when frozen solutions (glasses) of visual pigments at 77°K are illuminated with visible light, there are changes in the absorption spectrum of the pigments (1, 2, 3)....
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Chapter and Conference Paper
Dichroism in Rods during Bleaching
The long-lived intermediates in the rhodopsin bleaching sequence have been linked with the state of adaptation of isolated retinae (1, 2, 3, 4). Correlations of this type can only be made when the kinetics of ...
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Chapter and Conference Paper
Cyclic AMP and Photoreceptor Function
Our recent work (1,2,3,4) has indicated that rod outer segment preparations from a number of different vertebrate retinas contain adenyl cyclase with a specific activity significantly higher than any previousl...
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Chapter and Conference Paper
Interconversion of Metarhodopsins
When the highly colored visual pigments of the eye absorb light, they communicate this fact to the membrane of the receptor cell in which they reside. This process of converting the energy of absorbed light in...
