Retina, of vertebrates

A second class of neuronal calcium sensors is formed by the guanylate cyclase-activating protein (GCAP). The GCAPs are expressed only in the photoreceptor cells of the retina of vertebrates. Recoverins and GCAPs have antagonistic roles in phototransduction. 

Herault J 1996 A model of colour processing in the retina of vertebrates from photoreceptors to colour opposition and colour constancy phenomena. Neurocomputing 12, 113-129. 

Recently Inoue and coworkers also reported ab initio study of shieldings for linear jr-conjugated systems. A photoreceptive protein such as rhodopsin (Rh) or bacte-riorhodopsin (bR) possesses a retinal isomer bound to a lysine residue via the protonated Schiff base linkage. Rh exists in the rod cell of the retina of vertebrate and possesses 11 -c/s-rcli iial (Figure 2), which is isomerized into the al l-Zraw.v form by the absorption of photons, finally leading to signal transduction. 

The retina of vertebrates has two kinds of cells that contain rhodopsin rods and cones. Cones function in bright light and are used for color vision they are concentrated in the central portion of the retina, called the macula, and are responsible for the greatest visual acuity. The remaining area of the retina consists mostly of rods, which are used for peripheral and night vision. 11-c/s-Retinal is present in both cones and rods. Rods have one kind of opsin, whereas cones have three kinds—one for blue, one for green, and one for red color vision. 

Glutaminase occurs in brain cortex and retina of vertebrates, and in rabbit and guinea pig kidney. It converts glutamine into glutamic acid and ammonia. 

Using a rapid flow technique, where a jet of molecules solved in a liquid flows through a focused laser beam, it is possible to study also photolabile molecules, such as rhodopsin, by resonance Raman spectroscopy [14.32]. This allows investigation of the interesting problem about the molecular mechanisms and dynamics of visual excitation. Rhodopsin molecules act as photoreceptors in the retina of vertebrates. If the rhodopsin sample is rapidly flowed through the focused laser beam, the fraction of isomerized molecules within the illuminated region stays small. This allows measurement of the resonance... 

The vitreous is a transparent extracellular matrix occupying the space between the posterior lens and the retina and, in the majority of vertebrate species, constitutes the major f)art of the volume of the eye. Embryo-logically it can be considered as the basement membrane of the retina. It provides a mechanical support for surrounding tissues and acts as a shock absorber by virtue of its viscoelastic properties (Balzas and Delinger, 1984). Vitreous consists mainly of water (98%) and colloids (0.1%) with ions and low molecular weight solutes making up the remainder. It is not fully developed at birth, and changes in both volume and chemical composition occur postnatally. 

Polyunsaturated fatty acids, containing 4,5, or 6 double bonds and chain lengths of up to C36 are found in phosphatidylcholine of vertebrate retinas.121 Although the double bonds are rarely in conjugated positions in food fats and in animal bodies, some plants convert oleic or linoleic acid into fatty acids with as many as three or four conjugated double bonds.1213 Conjugated linoleic acid (9c, lit 18 2) can... 

Schultz K, Stell WK (1996) Immunocytochemical localization of the high-affinity glutamate transporter, EAACI, in the retina of representative vertebrate species. Neurosci Lett 2// 191-194. 

The true nature of this molecule has been hard to identify unequivocally, however. Recent experiments with antibodies to the 68 kDa laminin receptor have shown that it may be used as a positional marker for dorsal embryonic retina, in a variety of vertebrates (Rabacchi et al., 1990). Similar work by McCaffery et al. (1990) has shown that the dorso-ventral asymmetry of this protein has 4 peculiarities in immunoblots the molecular mass of the receptor is not 68 kDa, but 43 kDa the molecular mass of the protein deduced from cDNA is only 33 kDa (see also Auth and Brawerman, 1992) the antibodies stain a cytoplasmic antigen, not a cell surface protein and, despite the pronounced dorso-ventral difference seen after immunostaining, the 43 kDa protein identified by immunoblotting appears evenly distributed throughout the retina. The authors concluded from sequence homology that the molecule may constitute a translation-initiation factor that reflects asymmetries in some aspect of protein translation. Attempts to further characterize this receptor have been both controversial and difficult, although it is possible that it shares identity with a molecule identified as a joint elastin/laminin receptor (Martin and Timpl, 1987). 

ACYL GROUPS, MOLECULAR SPECIES, AND LABELING BY Cr-GLYCEROL AND H-ARACHIDONIC ACID OF VERTEBRATE RETINA GLYCEROLIPIDS... 

Young, R. W. The organization of vertebrate photoreceptor cells. In The Retina Structure, function and clinical characteristics (eds. Straatsma, B., Allen, R., Hall, M. and Crescitelli, F., pp. 177-209. University of California Press, Los Angeles, 1969. 

Melatonin. Melatonin (A/-acetyl-5-metlioxytryptaniine) [73-31-4] C 2H gN2O2(250) is secreted from the pineal gland and retina during dark periods of the vertebrate circadian rhythm (65). Melatonin regulates biological rhythms and neuroendocrine function and is formed from serotonin (5-HT). 

The vertebrate retina contains two classes of light-sensitive receptor cells called rods and cones. The rod is an elongated cylindrical cell containing several hundred thylakoids which support the visual pigment. The pigment system in the rod is confined to internal membranes situated close to the outer membrane of the cell. In the other type of visual receptor, the cone, the pigment is situated in the external membrane itself. In the cone the external... 

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