Disease relevance of Photoreceptors, Vertebrate

• CONCLUSIONS: This TULP1 splice-site mutation in homozygotes causes early-onset, severe retinal degeneration involving macular and peripheral cones and rods [1].

Psychiatry related information on Photoreceptors, Vertebrate

• Because rd gene induces different age-related degeneration of cones and rods, we have examined age-related changes in the sensitivity to a light pulse for phase-shifting the locomotor activity rhythms in CBA/J-rd/rd mice [2].

High impact information on Photoreceptors, Vertebrate

• When light is absorbed within the outer segment of a vertebrate photoreceptor, the conformation of the photopigment rhodopsin is altered to produce an activated photoproduct called metarhodopsin II or Rh(*) [3].
• Cyclic-nucleotide-gated (CNG) channels in outer segments of vertebrate photoreceptors generate electrical signals in response to changes in cyclic GMP concentration during phototransduction [4].
• Cyclic nucleotide-gated (CNG) channels serve as downstream targets of signalling pathways in vertebrate photoreceptor cells and olfactory sensory neurons (see ref. 1 for review) [5].
• Rod outer segments (ROSs) of vertebrate photoreceptor cells have been reported to contain several enzyme systems including a dark, Ca2+-stimulated ATPase, a rhodopsin kinase, a phosphodiesterase and a GTPase, all of which are light-stimulated [6].
• Recoverin, a calcium ion (Ca2+)-binding protein of vertebrate photoreceptors, binds to photoreceptor membranes when the Ca2+ concentration is greater than 1 micromolar [7].

Biological context of Photoreceptors, Vertebrate

• The encoded protein has 401 amino acid residues and a molecular mass of 44,972 daltons, and it shares approximately 42 percent amino acid sequence identity with arrestin (S-antigen), which has been proposed to quench the light-induced cascade of guanosine 3',5'-monophosphate hydrolysis in vertebrate photoreceptors [8].
• When driven exclusively by either cones or by rods, CNQX/DNQX hyperpolarized the L-HC and reduced its light response, without altering response kinetics, indicating that both rods and cones communicate with L-HCs at ionotropic glutamatergic synapses [9].
• A number of phototransducing proteins in vertebrate photoreceptors contain a carboxyl terminal -CXXX motif (where C = cysteine and X = any amino acid), known to be a signal sequence for their post-translational prenylation and carboxyl methylation [10].
• To gain insights into the molecular differences between rods and cones, we compared the gene expression profile of the rod-dominated retina of wild type mouse with that of the cone-only retina of Nrl(-/-) (Neural retina leucine zipper knockout) mouse [11].
• Recoverin is a Ca(2+)-binding protein that may play a role in vertebrate photoreceptor light adaptation by imparting Ca2+ sensitivity to rhodopsin kinase [12].

Anatomical context of Photoreceptors, Vertebrate

• Cyclic GMP releases calcium from disc membranes of vertebrate photoreceptors [13].
• A vertebrate photoreceptor cell contains a small cluster of actin filaments in its connecting cilium at the site where new transductive disk membranes are formed [14].
• We have examined the modulation of GABA-elicited transport currents of retinal horizontal cells by glutamate, the likely neurotransmitter of vertebrate photoreceptors [15].
• In diabetic rats, reduced levels of IGFBP-6 mRNA were detectable, whereas levels of IGFBP-5 mRNA were increased in the inner and outer retina, rods and cones, iris, cornea, and ciliary body [16].
• Arginine, the precursor for formation of nitric oxide, was present in glial cells, and in the paraboloids of both rods and cones [17].

Associations of Photoreceptors, Vertebrate with chemical compounds

• In vertebrate photoreceptors, light reduces cyclic GMP concentration and closes cGMP-activated channels to induce a hyperpolarizing response [18].
• The resynthesis of cGMP in vertebrate photoreceptors by guanylate cyclase is one of the key events leading to the reopening of cGMP-gated channels after photoexcitation [19].
• It is evident that a prolonged exposure to filipin in fixative enhances rather than reduces presumptive cholesterol detection in the vertebrate photoreceptor cell [20].
• L-Glutamate is a leading candidate for the vertebrate photoreceptor transmitter [21].
• We have isolated and characterized a cDNA clone that encodes the gamma subunit of transducin, the guanine nucleotide binding regulatory protein found in vertebrate photoreceptors [22].

Gene context of Photoreceptors, Vertebrate

• In Aipl1(-/-) retinas, the outer nuclear layer develops normally, but rods and cones then quickly degenerate [23].
• Consistent with expression of RPGR in rods and cones, our results show that mutations in RPGR, in addition to X-linked RP, can also cause cone-specific degeneration [24].
• Thus, these studies suggest that rods and cones, express the same form of GRK1 [25].
• These findings support the hypothesis that IRBP is synthesized by the rods and cones, and suggest that its synthesis and secretion are initiated when the photoreceptor inner segments start to differentiate [26].
• This and a previous study reveal that CaBP4 is critical for signal transmission from rods and cones to second-order neurons [27].

Analytical, diagnostic and therapeutic context of Photoreceptors, Vertebrate

• Immunocytochemistry localizes SPACR to the matrix surrounding rods and cones (Acharya, S., Rayborn, M. E., and Hollyfield, J. G. (1998) Glycobiology 8, 997-1006) [28].
• Molecular cloning and characterization of chick sialoprotein associated with cones and rods, a developmentally regulated glycoprotein of interphotoreceptor matrix [29].
• Frozen sections of retinas from rabbit (mostly rods), ground squirrel (mostly cones), and monkey (mixed rods and cones) were freeze dried, and samples from all the discrete layers analyzed for the enzymes which form cyclic GMP and subsequently convert it back to GTP [30].
• In this study, we have compared spatial and temporal aspects of development of new rods and cones in the adult goldfish by using a combination of bromodeoxyuridine immunocytochemistry and opsin in situ hybridization to determine the intervals between terminal mitosis (cell "birth") and expression of opsin mRNA for each photoreceptor cell type [31].
• Using pre- and post-embedding immunostaining and electron microscopy, bassoon was localized in the outer plexiform layer at ribbon synapses formed by rods and cones but was absent from basal synaptic contacts formed by cones [32].

References