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Topic: Phototransduction

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	Phototransduction
		Phototransduction in transgenic mice after targeted deletion of the rod transduc...
		Different Phototransduction Kinetics of Phytochrome A and Phytochrome B in Arabi...
		Growth factors regulate phototransduction in retinal rods by modulating cyclic n...
	www.scienceoxygen.com /biology/437.html (292 words)

	[Entrez medline Query]
		Phototransduction is the best studied example of a GTP binding protein (G protein)-coupled signal transduction pathway.
		Although rhodopsin's role in activating the phototransduction cascade is well known, the processes that deactivate rhodopsin, and thus the rest of the cascade, are less well understood.
		The complex mechanism of phototransduction and the presence of four different voltage-gated conductance in Limulus ventral nerve photoreceptors indicate that these cells are far less differentiated than the photoreceptor cells of vertebrates.
	www.sfu.ca /biology/courses/bisc372/phototransduction.html (3861 words)

	UIC - Bioengineering
		Phototransduction refers to the biochemical process which translates light entering photoreceptor cells (rods and cones) in the eye into the beginnings of a neural signal.
		I am continuing to develop an use novel electroretinographic techniques (paired-flash electroretinography) to study phototransduction in intact animals.
		Goals are to elucidate the mechanisms of light adaptation and recovery, and to use these techniques to study defects in the phototransduction mechanism related to eye disease.
	www.uic.edu /depts/bioe/faculty/j_hetling/john_research_int.htm (397 words)

	Ubiquitinylation and Ubiquitin-dependent Proteolysis in Vertebrate Photoreceptors (Rod Outer Segments). EVIDENCE FOR ...
		In corroboration of the hypothesized regulation of phototransduction proteins by the ubiquitin-dependent pathway, we identified free ubiquitin (8 kDa) and ubiquitin-protein conjugates (50 to >200 kDa; pI 5.3-6.8 by two-dimensional electrophoresis) in bovine rod outer segments (ROS).
		Phototransduction (the conversion of light into a nerve impulse) in the vertebrate eye occurs within the retina in highly specialized compartments, called outer segments, of rod and cone cells.
		Tight control of phototransduction protein interactions is required for adaptational response to light (2, 3, 4, 5, 6, 7) and for photoreceptor cell viability (8, 9, 10, 11, 12).
	www.jbc.org /cgi/content/full/271/24/14473 (10300 words)

	Rolling blackout, a newly identified PIP2-DAG pathway lipase required for Drosophila phototransduction - Nature ...
		This complete blockade of phototransduction is due only to loss of rbo function, as the addition of a single copy of the wild-type genomic rbo gene fully restored the ERG (Fig.
		Phototransduction block in rbo temperature-sensitive mutants is activity dependent and recovers in the dark at restrictive temperature.
		The dark interval−dependent recovery of phototransduction at restrictive temperature may indicate a secondary pathway for regenerating this factor, which is rate limiting in the absence of RBO function owing to rapid, light-activated consumption.
	www.nature.com /uidfinder/10.1038/nn1313 (6288 words)

	Vertebrate Phototransduction: Activation, Recovery, and Adaptation (Site not responding. Last check: 2007-11-06)
		Phototransduction is the best studied example of a GTP binding protein (G protein)-coupled signal transduction pathway.
		A great body of knowledge about phototransduction has been established in the past several decades but there are still many unanswered questions, particularly about photoresponse recovery and adaptation.
		The purpose of this review is to outline the events following photon absorption by vertebrate photoreceptors, to demonstrate the great complexity of the phototransduction cascade mechanisms, and to point out some of the controversies arising from recent findings in the field of visual transduction.
	www.lf2.cuni.cz /physiolres/1998/issue3/iss3cl1.htm (150 words)

	Nansi J. Colley - Neuroscience Training Program
		Phototransduction in Drosophila utilizes a G protein-coupled phospholipase-C-mediated signaling cascade that is regulated by calcium.
		We are focused on the precise targeting and transport mechanisms that assemble the constituents of phototransduction.
		During biosynthesis, the members of phototransduction are specifically targeted and transported to the rhabdomeres.
	ntp.neuroscience.wisc.edu /faculty/colley.html (305 words)

	Preliminary evidence for a change in spectral sensitivity of the circadian system at night
		An increase in the percentage of melatonin suppression and an increase in pupil constriction for the mercury source relative to the blue light source at night were found, suggesting a temporal change in the contribution of photoreceptor mechanisms leading to melatonin suppression and, possibly, iris constriction by light in humans.
		Since pupil size is determined, in part, by the retinal exposure to light and, thus influences the amount of melatonin suppression 22, the difference between melatonin suppression by the Hg and LED spectra would have been relatively larger if pupil sizes were held constant throughout the experiment.
		The results presented here are the first to suggest a temporal change in spectral sensitivity of the human circadian system phototransduction at two different times during the night, measured through nocturnal melatonin suppression, and with less certainty (owing to the inherent variability of the iris constriction response) through pupil area.
	www.jcircadianrhythms.com /content/xml/1740-3391-3-14.xml (4256 words)

	Charles S. Zuker, Professor of Biology, UCSD, Investigator, Howard Hughes Medical Institute (Site not responding. Last check: 2007-11-06)
		In particular, we have focused on the molecular genetics of phototransduction, mechanotransduction and taste transduction.
		Phototransduction is an ideal model system for the study of G protein-coupled signaling cascades.
		Phototransduction in Drosophila is a phosphoinositide-mediated, calcium-regulated signaling pathway.
	biology.ucsd.edu /faculty/zuker.html (930 words)

	Dr. Russell Hamer Lab
		We are working to develop a comprehensive model of vertebrate rod phototransduction that is able to account for rod responses over the full gamut of their response repertoire, from single-photon responses to highly light-adapted responses.
		He is primarily involved in the development and implementation of computational models of the vertebrate phototransduction cascade, and the numerical optimization of these models to account for a wide array of physiological data.
		Moreover, he is one of the few researchers in any field whose work links the mechanisms of the system across all levels, from the molecular (biochemical basis of phototransduction), to the cellular (electrophysiological properties of rods and cones), to the organic (electroretinographic analysis of photoreceptor function), to the organismic (psychophysics, behavior).
	www.ski.org /Affiliates/RHamer_lab (1035 words)

	Molecular Cardiology Research Institute - Retina Research Lab Home Page (Site not responding. Last check: 2007-11-06)
		The phototransduction cascade is the fastest known biological process and among the most intensively studied of the G-protein regulated signaling pathways.
		A second objective of studies in the Lem lab is to investigate the role of transducin in retinal degenerative disease and phototransduction signaling mechanisms.
		Phototransduction in transgenic mice after targeted deletion of the rod transducin ∝-subunit.
	www.tufts-nemc.org /mcri/MCRILabs/RetinaResearchLab/default (477 words)

	Interactive Fly, Drosophila
		In vertebrate phototransduction, which is characterized by signal amplification at the early stages of the cascade, the shape of the bump is, at least partially, determined at the stages of rhodopsin and G-protein action.
		In Drosophila, phototransduction is mediated by Gq-activation of phospholipase C and is a well studied model system for understanding the kinetics of signal initiation, propagation and termination controlled by G proteins.
		The spatial localization and connectivity of relevant proteins would help explain why the Drosophila phototransduction pathway is one of the fastest G protein-coupled signaling cascades known, with activation and termination occurring within tens of milliseconds.
	www.sdbonline.org /fly/hjmuller/inad3.htm (4017 words)

	NEUROSCIENCE : Julie Schnapf (Site not responding. Last check: 2007-11-06)
		To study the earliest stages of phototransduction we use suction electrodes to measure photocurrent in single rod and cone outer segments of human and monkey eyes and compare this to corresponding measures of human visual perception.
		The brightness of colored lights and the appearance of color mixtures could be predicted from the measured wavelength dependence of the responses in single rods and cones.
		To look at these later stages of phototransduction we use patch electrodes to record the photovoltage of primate photoreceptors.
	www.ucsf.edu /neurosc/faculty/neuro_schnapf.html (476 words)

	Charles S. Zuker
		Phototransduction converts the energy of a photon of light into a signal that the nervous system can understand.
		Drosophila phototransduction is a G protein–coupled, phosphoinositide-mediated, and calcium-regulated signaling cascade that serves as a model system for a genetic and physiological dissection of G protein–coupled signaling in vivo.
		In Drosophila, the phototransduction machinery is housed in a specialized membrane organelle, the rhabdomere.
	www.hhmi.org /research/investigators/zuker.html (1389 words)

	Phototransduction in Drosophila melanogaster -- Hardie 204 (20): 3403 -- Journal of Experimental Biology
		Phototransduction in Drosophila melanogaster -- Hardie 204 (20): 3403 -- Journal of Experimental Biology
		An enlargement of the circled area in the inset, showing the base of one microvillus with associated phototransduction machinery, is shown schematically in the main figure.
		Phillips, A. M., Bull, A. and Kelly, L. Identification of a Drosophila gene encoding a calmodulin-binding protein with homology to the trp phototransduction gene.
	jeb.biologists.org /cgi/content/full/204/20/3403 (4703 words)

	Rescue of the Drosophila phototransduction mutation trp by germline transformation -- Montell et al. 230 (4729): 1040 ...
		Rescue of the Drosophila phototransduction mutation trp by germline transformation -- Montell et al.
		Phototransduction is the process by which light-stimulated photoreceptor cells of the visual system send electrical signals to the nervous system.
		In order to facilitate molecular studies of phototransduction, the trp gene was isolated and its identity was confirmed by complementing the mutant trpCM allele of the trp gene by P-element mediated germline transformation of a 7.1-kilobase DNA fragment.
	www.sciencemag.org /cgi/content/abstract/230/4729/1040 (615 words)

	Charles S. Zuker, Professor of Biology, UCSD, Investigator, Howard Hughes Medical Institute
		Phototransduction is an ideal model system for the study of G protein-coupled signaling cascades.
		The study of this signaling cascade in the fruit fly make it possible to use powerful molecular genetic techniques to identify novel transduction molecules, and then to examine the function of these molecules in vivo, in their normal cellular and organismal environment.
		Phototransduction in Drosophila is a phosphoinositide-mediated, calcium-regulated signaling pathway.
	www-biology.ucsd.edu /faculty/zuker.html (930 words)

	Susan Tsunoda
		The rhabdomere is the site of phototransduction, the signaling compartment, where photons of light are captured and transformed into an electrical signal to be transmitted to the brain.
		Localization of phototransduction components to the rhabdomere, the signaling compartment of the photoreceptor cell, has, until recently, been thought to be static.
		We have shown that the Gq subunit of the heterotrimeric G-protein regulating phototransduction undergoes light-dependent translocation.
	www.bu.edu /biology/Faculty_Staff/tsunoda.html (1366 words)

	BBSPrints Archive: STRUCTURAL PROPERTIES AND ROLE IN PHOTOTRANSDUCTION
		As a result, it plays a central role in the phototransduction process in rod and cone photoreceptor cells.
		Recent studies also indicate that calmodulin binds to the 240 kDa protein of the channel complex and modulates the sensitivity of the channel for cGMP in a Ca2+ dependent manner.
		The molecular properties of the channel complex and the possible role of Ca2+-calmodulin modulation of the channel during photoactivation and photorecovery is discussed in relation to the current mechanism of phototransduction in photoreceptor cells.
	www.bbsonline.org /documents/a/00/00/05/17/index.html (428 words)

	Acceleration of Key Reactions as a Strategy to Elucidate the Rate-Limiting Chemistry Underlying Phototransduction ...
		PDE activity recovered to its dark level as phototransduction was quenched.
		The rate of PDE decay was approximated with a single exponential fit of the declining phase (bold trace) of the response.
		Kinetic Parameters of Phototransduction Inactivation in the Presence and Absence of Hydroxylamine and Recoverin
	www.iovs.org /cgi/content/full/44/3/1016 (4467 words)

	Washington University Ophthalmology > Faculty > Kefalov Lab > Projects
		That involves a systematic study of mouse cone function and the role of various phototransduction proteins in determining their properties by using genetically modified animals.
		We can also use this approach to study the mechanisms by which known mutations of cone phototransduction proteins cause disease.
		The second part of our research focuses on the differences between rod and cone phototransduction proteins in order to understand how they affect photoreceptor properties.
	ophthalmology.wustl.edu /faculty/kefalov/projects.html (334 words)

	Faculty Membership Application
		The research in my lab centers on the molecules involved in phototransduction-- the biochemical process by which photons are converted into a neural signal.
		The phototransduction enzyme cascade is an exquisitely sensitive system, being capable of producing a neural response to a single photon.
		One of the many exciting things about phototransduction is that much of the process is conserved across ALL animals that have eyes, from the slimy flatworms to the crunchy insects and right on up to humans.
	www.mbi.ufl.edu /people/fac-form.php?id=22 (377 words)

	Effect of 11-Cis 13-Demethylretinal on Phototransduction in Bleach-adapted Rod and Cone Photoreceptors -- Corson et al. ...
		Phototransduction in dark-adapted rods in the presence of 11-cis 13-demethylretinal.
		a significant deactivation of the cone phototransduction cascade.
		A model of the mechanism of activation by 11-cis 13-demethylretinal of phototransduction in rods.
	www.jgp.org /cgi/content/full/116/2/283 (7713 words)

	Pharmacology: Case Western Reserve University
		Light-triggered events initiated in rod and cone outer segments were the subject of numerous investigations during the last two decades, most notably using molecular approaches and electrophysiological measurements of the isolated retina or photoreceptor cells.
		Many unresolved issues relevant to phototransduction, light- and dark-adaptation, and the chemical processing of retinoid cycle intermediates remain unanswered, including the enzymology of the retinoid cycle, the mechanisms by which these intermediates diffuse within and between the photoreceptors and the RPE, and the dependence of phototransduction reactions on the operation of the cycle.
		Knowledge about phototransduction in the retina, a system with great experimental advantages, will improve further understanding of similar events in hormonal signaling, cellular communication and immune regulation, and provide baseline information for further studies of retinal disease processes.
	pharmacology.case.edu /department/faculty/palczewski (524 words)

	Amazon.com: phototransduction (Site not responding. Last check: 2007-11-06)
		CMOS Imagers: From Phototransduction to Image Processing (Fundamental Theories of Physics) by Orly Yadid-Pecht and Ralph Etienne-Cummings (Hardcover - Dec 12, 2005)
		Phototransduction in rods and cones (Massachusetts Institute of Technology.
		for their role in Drosophila phototransduction, are a family of hexa-...
	www.amazon.com /s?ie=UTF8&keywords=phototransduction&index=blended&page=1 (978 words)

	Eurekah - Recoverin and Rhodopsin Kinase (Site not responding. Last check: 2007-11-06)
		The majority of proteins involved in vertebrate phototransduction are expressed specifically in photoreceptors.
		The electrical signals resulting from phototransduction are decomposed by bipolar cells and then encoded into spike trains by ganglion cells.
		Visual phototransduction, the conversion of incoming light to an electrical signal, takes place in the outer segments of the rod and cone photoreceptor cells.
	www.eurekah.com /chapter/672 (1338 words)

	Excised Patches of Plasma Membrane from Vertebrate Rod Outer Segments Retain a Functional Phototransduction Enzymatic ...
		For example, in excised patches of vertebrate rod outer segment plasma membrane, the cGMP-activated cation channels have traditionally been studied in room light because the enzyme cascade linking photon absorption to channel closure was assumed to be inoperative.
		To investigate the possibility that, in fact, such excised patches retain a functional phototransduction enzymatic cascade, this same preparation was studied in darkness.
		These results (i) establish that excised patches from rod outer segment retain functional phototransduction enzymes, (ii) support the classical view that channel opening is modulated by phosphodiesterase-mediated cGMP hydrolysis, and, most surprisingly, (iii) demonstrate that diffusion in excised patches is so restricted that local enzymes can induce variations in the concentration of small molecules.
	www.pnas.org /cgi/content/abstract/87/11/4226 (385 words)

	Framework Developed for Testing How Lighting Can Affect Human Health
		The "circadian phototransduction" model offers a framework for testing and exploring the practical aspects of architectural lighting and how it can affect human health.
		LRC scientists plan to extend and refine the circadian phototransduction model, as well as bridge the findings to practical applications.
		The research is summarized in a paper titled, "A model of phototransduction by the human circadian system," available in the Brain Research Reviews journal online and will be published in an upcoming print edition of the journal.
	www.lrc.rpi.edu /resources/news/pressreleases/phototransduction.asp (600 words)

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