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Topic: Invertebrate photoreceptor

	Invertebrate Differences by Ronald L. Shimek, Ph.D. - Reefkeeping.com
		Invertebrates are often seen as a single group of animals, similar in many regards to the more familiar vertebrates such as dogs, cats or fishes; such a conception is both wrong and misleading and can result in significant problems in caring for them.
		While incapable of forming a fine image, such a photoreceptor would be very well adapted to detecting movement by the continual flickering of ommatidia on and off as objects passed through their small discrete units.
		Vertebrate eyes are indirect eyes, the photoreceptor cells, the rods and the cones, face away from the incoming light and in effect respond to the light bouncing off a reflective layer at the back of the retina called the tapetum.
	www.reefkeeping.com /issues/2003-08/rs/index.php (2723 words)

	Publications: LISMAN - NEUROSCIENCE
		Cyclic GMP is involved in the excitation of invertebrate photoreceptors.
		Inactivation of squid rhodopsin in the absence of phosphorylation.
		Shin, J., Richard, E.A., and Lisman, J.E. Ca2+ is an obligatory intermediate in the excitation cascade of Limulus photoreceptors.
	www.bio.brandeis.edu /lismanlab/pubs.html (1683 words)

	Literature of Arendt Team (Site not responding. Last check: 2007-10-14)
		In the eye, the various types of photoreceptor cells, as well as pigment and lens cells, each require distinct combinations of specifying transcription factors that control their particular differentiation programmes, such as opsin expression in photoreceptors, specific neurotransmitter metabolism, or axonal outgrowth.
		This is exemplified here on the evolution of ciliary and rhabdomeric photoreceptor cells in bilaterian eyes and on the evolution of cell type diversity in the vertebrate retina.
		I propose that the retinal ganglion, amacrine and horizontal cells are evolutionary sister cell types that evolved from a common rhabdomeric photoreceptor cell precursor.
	www-db.embl-heidelberg.de /jss/emblGroups/g_lits_172.html (534 words)

	[Entrez medline Query]
		Rod outer segment renewal in retinal rod photoreceptors is mediated by polarised sorting of rhodopsin, and its associated proteins and lipids, on post-Golgi vesicles that bud from the trans-Golgi network and fuse with the specialised domain of the plasma membrane in the rod inner segment.
		Insect photoreceptor cells are polarized epithelial cells; their plasma membrane is organized into two domains having a distinct morphology, molecular composition, and function.
		The fates of the photoreceptors are determined exclusively by inductive interactions between neuronal precursors in the cell cluster from which the ommatidium is formed.
	www.sfu.ca /biology/courses/bisc372/photoreceptors.html (1301 words)

	Orem, Mol Vis 2002; 8:455-461.
		Photoreceptor cell structural defects [10,11], improper trafficking of rhodopsin [12-14], and constitutive activity of the phototransduction cascade [15-17] are examples of mechanisms that have been elucidated for specific mutations in the Drosophila visual system.
		The photoreceptor cells are approximately 100 μm long and are characterized by a collection of approximately 10,000 microvilli that project into the intraommatidial space.
		Rescue of photoreceptor degeneration in rhodopsin-null Drosophila mutants by activated Rac1.
	www.molvis.org /molvis/v8/a55 (3995 words)

	photoreceptor cells from Office, Business, Teaching & Educational Resources (Site not responding. Last check: 2007-10-14)
		Presented in 2000, "Calcium influx, diffusion and extrusion in fly photoreceptor cells" is the PhD thesis of Johannes Oberwinkler of the Faculty of Science at...
		The photoreceptor cells are at the back of the retina, and...
		core of 8 photoreceptor cells (R1-R8) surrounded by 4 cone cells (equivalent to the vertebrate lens in function) pigment cells and a sensory bristle...
	www.wup.org.uk /photoreceptor-cells.html (269 words)

	Literature of Arendt Team (Site not responding. Last check: 2007-10-14)
		The cerebral eyes in errant polychaetes represent prototype invertebrate pigment-cup ocelli and thus resemble the presumed ancestral eyes.
		Using Platynereis rhabdomeric opsin as differentiation marker, we show that the first pair of adult eye photoreceptor cells is detected within bilateral clusters that transitorily express ath, the Platynereis atonal orthologue, thus resembling proneural sensory clusters.
		This is highly significant because on the molecular level we find that for phototransduction rhabdomeric versus ciliary photoreceptor cells employ divergent rhodopsins and non-orthologous G-proteins, rhodopsin kinases and arrestins.
	www-db.embl-heidelberg.de /jss/emblGroups/g_lit_172.html (1786 words)

	ScienceWeek
		Invertebrates have not, however, been suggested as a means to unraveling mechanisms of complex function that are relevant to human cognition.
		Invertebrate brains are not part of the picture.
		In higher invertebrates and vertebrates, it is clear that memory mechanisms related to behavioral experiences depend on the brain.
	scienceweek.com /2004/sa040423-1.htm (1254 words)

	Noise and Natural Scene Statistics (Site not responding. Last check: 2007-10-14)
		Retinal photoreceptors generate discrete electrical events in the dark indistinguishable from those evoked by light and the resulting dark signals limit visual sensitivity at low levels of illumination.
		The random spontaneous events are strongly temperature dependent and in both vertebrate and invertebrate photoreceptors require activation energies usually in the range of 23 to 28 kcal mol(-1).
		Recent molecular orbital studies and pH experiments on horseshoe crabs (Limulus) suggest that the thermal isomerization of a relatively unstable form of rhodopsin, one in which the Schiff-base linkage between the chromophore and protein is unprotonated, is responsible for thermal noise.
	www.biology.ucsd.edu /labs/reinagel/nnss/barlow2.html (232 words)

	Hartman, Mol Vis 2001; 7:95-100.
		Photoreceptor membrane turnover involves a precise balance between the biosynthesis and assembly of new membrane constituents and the process of photoreceptor membrane shedding [1-3].
		Since the processes of photoreceptor membrane biosynthesis and shedding may be regulated by different mechanisms, even within the same organism, we investigated whether the levels of rhodopsin (Rh1), arrestin1 (arr1), and arrestin2 (arr2) varied over the 12L/12D cycle in Drosophila.
		As part of the photoreceptor renewal process in vertebrates, rhodopsin is synthesized in the proximal inner segment and is transported to the outer segment via the connecting cilium [1,51,52].
	www.molvis.org /molvis/v7/a14 (3789 words)

	QMUL > Department of Biological Sciences
		SGC-immunoreactivity was detected in several classes of identifiable neurons including photoreceptor cells of the locust eyes, ocellar interneurons, olfactory interneurons and antennal mechanosensory neurons (Elphick and Jones, 1998).
		Detailed analysis of SGC expression in photoreceptor cells of the locust compound eye has revealed that SGC-alpha is localised in their rhabdomeric compartments where phototransduction occurs (Elphick and Jones, 1998; Jones and Elphick, 1999).
		This indicates that the NO-cGMP pathway may be involved in regulation of phototransduction in insect photoreceptors.
	www.biology.qmw.ac.uk /research/staff/elphick/elph_res2.htm (837 words)

	Invertebrate photoreceptors (from photoreception) -- Encyclopædia Britannica
		The photoreceptor of the jellyfish Polyorchis penicillatus is a modified cilium, or hairlike structure, as are the photoreceptors of many higher animals.
		Cilia are found in the cells of most animals; their motion is used either to move the animal or to move materials within or outside the body.
		The only trait that distinguishes invertebrates from vertebrates, or animals with backbones, is the absence or presence of a...
	www.britannica.com /eb/article-65142 (805 words)

	[No title]
		Their photoreceptor cell population is composed of only rods, and they contain a mere twenty million retina receptor cells compared to 126 million in humans.
		RPE touches the extremities of the photoreceptors, both the rods and the cones, and the microvilli interdigitate with their sides.
		Surrounding each photoreceptor RPE retina cell also requires increasing the space between the photoreceptors, further decreasing the amount of light able to strike the photoreceptors, consequently lowering vision resolution.
	www.asa3.org /asa/PSCF/2000/PSCF3-00Bergman.html.ori (8884 words)

	Calcium Transients in the Rhabdomeres of Dark- and Light-Adapted Fly Photoreceptor Cells -- Oberwinkler and Stavenga 20 ...
		Invertebrate photoreceptor cells can adjust their sensitivity to the average light level they encounter, i.e., they show pronounced
		Howard J, Blakeslee B, Laughlin SB (1987) The intracellular pupil mechanism and photoreceptor signal:noise ratios in the fly Lucilia cuprina.
		Peretz A, Suss-Toby E, Rom-Glas A, Arnon A, Payne R, Minke B (1994) The light response of Drosophila photoreceptors is accompanied by an increase in cellular calcium: effects of specific mutations.
	www.jneurosci.org /cgi/content/full/20/5/1701 (6302 words)

	Nat' Academies Press, (NAS Colloquium) Vision: From Photon to Perception (1999)
		Invertebrate vision too begins with the activation of a G protein by photoexcited rhodopsin.
		As was discussed by Charles Zuker (5), the cascades of vertebrates and invertebrates then diverge.
		All information captured by 125 million photoreceptor cells in humans is carried into the brain by only 1 million ganglion cell axons.
	www.nap.edu /books/0309068347/html/1.html (3997 words)

	"Information resources on the care and use of molluscs"
		In a second experiment, simultaneous recordings were made in type B and A photoreceptors, and paired training was found to produce an increase in the amplitude of the IPSP in the A photoreceptor in response to an evoked spike in the B‑cell.
		Importantly, there was no change in the initial slope of the postsynaptic IPSP in the A photoreceptor, suggesting that spike duration‑independent mechanisms of neurotransmitter exocytosis or postsynaptic receptor sensitivity did not contribute to the observed synaptic facilitation.
		The occlusion of the effects of 4‑AP by paired training was not attributable to a saturation of the capacity of the B‑cell for transmitter exocytosis, because it was observed that tetraethylammonium (TEA)‑induced inhibition of the delayed voltage‑dependent K(+) current induced both spike broadening and synaptic facilitation regardless of training history.
	www.nal.usda.gov /awic/pubs/molluscs/labgast.htm (9609 words)

	Peter O'Day
		The principal focus has been visual processing in invertebrate retina, including the physiology and chemistry of phototransduction and the processing of circadian information from higher brain centers to the retina.
		Photoreceptors from the eyes of Limulus and of Drosophila are used.
		Visual transduction and signal processing within each photoreceptor involve complex cascades of reactions, initiating several other simultaneous intracellular and membrane events that lead to the creation of an intricate electrical response that spreads to the synapse, sending information to higher order visual cells.
	www.neuro.uoregon.edu /ionmain/htdocs/faculty/oday.html (538 words)

	[No title]
		Verted eyes are wired so the photoreceptors face toward the light and the nerves are placed behind the photoreceptor layer.
		The major anatomical difference between the human eye and the advanced cephalopod eye, such as the octopus, is the retina, which is not only verted but also lacks a fovea centralis.
		One of their major functions is to collect the used retinal from the photoreceptors.
	www.asa3.org /ASA/PSCF/2000/PSCF3-00Bergman.html (8766 words)

	WASp is required for the correct temporal morphogenesis of rhabdomere microvilli -- Zelhof and Hardy 164 (3): 417 -- ...
		Expression of photoreceptor and rhabdomeric proteins at 36 h APF.
		the photoreceptor apical surface is delayed and disorganized.
		Identification of actin filaments in the rhabdomeral microvilli of Drosophila photoreceptors.
	www.jcb.org /cgi/content/full/164/3/417 (5628 words)

	Professor in The Department of Physiology and Biophysics at Boston University's Medical School (Site not responding. Last check: 2007-10-14)
		Nasi, E. and Gomez, M. Bridging the gap between vertebrate and invertebrate phototransduction: the light-activated conductance in molluscan hyperpolarizing photoreceptors.
		Gomez, M. and Nasi, E. Involvement of cyclic GMP in transduction in hyperpolarizing invertebrate photoreceptors.
		On the gating mechanisms of the light-dependent conductance in Pecten hyperpolarizing photoreceptors.
	biophysics.bumc.bu.edu /faculty/nasi/bibliography (1182 words)

	Molecular Basis for Ultraviolet Vision in Invertebrates -- Salcedo et al. 23 (34): 10873 -- Journal of Neuroscience
		Invertebrates are sensitive to a broad spectrum of light that
		ancestor with, the UV-absorbing pigments of invertebrates (e.g.,
		Tovee MJ (1995) Ultra-violet photoreceptors in the animal kingdom—their distribution and function.
	www.jneurosci.org /cgi/content/full/23/34/10873 (4453 words)

	UCLA Department of Physiological Science-- Homepage of Gordon Fain (Site not responding. Last check: 2007-10-14)
		In collaboration with Hugh Matthews and with the laboratories of Sue Brockerhoff, Fred Rieke, and Jim Hurley at the University of Washington in Seattle, we have measured this release from a zebrafish cone model that lacks one of the subunits of transducin, the G protein responsible for transduction in photoreceptors.
		We are also interested in the role of Ca2+ in photoreceptor degeneration during vitamin A deprivation and degenerative disease (for example, retinitis pigmentosa).
		Together with John Lisman of Brandeis University, we have proposed that some forms of degeneration produce death of the photoreceptors by a continuous activation of the visual cascade, a speculation we have called the ?equivalent light hypothesis?.
	www.physci.ucla.edu /physcifacultyindiv.php?FacultyKey=87 (1977 words)

	Light- and Ca2+-Modulated Heterotrimeric GTPases in the Eyespot Apparatus of a Flagellate Green Alga -- Calenberg et ...
		Foster, K.W., Saranak, J., Patel, N., Zarilli, G., Okabe, M., Kline, T., and Nakanishi, K. (1984) A rhodopsin is the functional photoreceptor for phototaxis in the unicellular eukaryote Chlamydomonas.
		Kröger, P., and Hegemann, P. (1994) Photophobic responses and phototaxis in Chlamydomonas are triggered by a single rhodopsin photoreceptor.
		Suzuki, T., Narita, K., Yoshihara, K., Nagai, K., and Kito, Y. (1995) Phosphatidyl inositol-phospholipase C in squid photoreceptor membrane is activated by stable metarhodopsin via GTP-binding protein, Gq.
	www.plantcell.org /cgi/content/full/10/1/91 (6324 words)

	Citations: Analog VLSI phototransduction by continous-time, adaptive, logarithmic photoreceptor circuits - Delbruck ... (Site not responding. Last check: 2007-10-14)
		This receptor, based on a model of the invertebrate retina, is able to adapt to over six orders of magnitude in light amplitude variation while maintaining its gain to local changes in brightness approximately constant.
		uses an adaptive photoreceptor circuit that adapts its operating point to the background intensity so that the pixel shows a high transient gain over 5 decades of background illumination.
		The circuit shown in Figure 1(a) can be transferred to an equivalent network of resistors and capacitors as shown in Figure 1(b) to obtain the transfer function of the....
	citeseer.ist.psu.edu /context/389804/0 (1232 words)

	Ionic mechanisms of phototransduction in photoreceptor cells from the epistellar body of the octopus eledone cirrhosa ...
		Ionic mechanisms of phototransduction in photoreceptor cells from the epistellar body of the octopus eledone cirrhosa -- Cobb and Williamson 202 (8): 977 -- Journal of Experimental Biology
		Roles of cyclic GMP and inositol trisphosphate in phototransduction of the mollusc extraocular photoreceptor.
		Involvement of cGMP in the excitation of invertebrate photoreceptors.
	jeb.biologists.org /cgi/content/refs/202/8/977 (951 words)

	Immediate Upstream Sequence of Arrestin Directs Rod-specific Expression in Xenopus -- Mani et al. 274 (22): 15590 -- ...
		in the retinal photoreceptor layer and pinealocytes (18), whereas
		expression in photoreceptor cells, pineal, lens, and brain (18).
		The retinal pigment epithelium (RPE), photoreceptors (PR), ganglion cell (GC) layers, and lenses (L) are indicated, and cone cells in the PR layer are indicated by arrows.
	www.jbc.org /cgi/content/full/274/22/15590 (5123 words)

	The properties of photoreceptors (from photoreception) -- Britannica Student Encyclopedia
		The photoreceptor cell absorbs light energy and transforms it into a nervous response.
		The actual photoreceptor component, or organelle, of the photoreceptor cell contains a coloured substance (visual pigment) that absorbs light and initiates the chain of chemical reactions leading to nervous excitation.
		More results on "The properties of photoreceptors (from photoreception)" when you join.
	www.britannica.com /ebi/article-65140 (902 words)

	Interactive Fly, Drosophila (Site not responding. Last check: 2007-10-14)
		The RPE is a monolayer of cuboidal cells that lies in close association with the rod and cone photoreceptors.
		The RPE functions in the phagocytosis of rod and cone outer segment fragments that are shed from their distal ends and regulate the uptake, processing, transport and release of retinoic acid and visual cycle intermediates (retinoids) and regulate ion transport in the subretinal space.
		The importance of the RPE for photoreceptor development and survival has been recognized for some time; indeed, the absence of RPE in vivo results in failure of retinal development, followed by degeneration and resorption of the retina.
	bioinformatics.weizmann.ac.il /databases/flybase/allied-data/interactive-fly/segment/hedghg2a.htm (9248 words)

	Preservation of light signaling to the suprachiasmatic nucleus in vitamin A-deficient mice -- Thompson et al. 98 (20): ...
		a non-opsin pigment is the primary circadian photoreceptor in
		Photoreceptor nuclei counts were obtained by counting nuclei within
		Extensive analyses have demonstrated that the classical photoreceptors (rods and cones) are not necessary for transmission
	www.pnas.org /cgi/content/full/98/20/11708 (4118 words)

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