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Mokhtar DM, Alesci A, Pergolizzi S, Zaccone G. Light and electron microscopic observations on retinal neurons of red-tail shark (Epalzeorhynchos bicolor H. M. Smith, 1931). Microsc Res Tech 2024; 87:1009-1019. [PMID: 38192121 DOI: 10.1002/jemt.24488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/26/2023] [Accepted: 12/18/2023] [Indexed: 01/10/2024]
Abstract
The structure of photoreceptors (PR) and the arrangement of neurons in the retina of red-tail shark were investigated using light and electron microscopy. The PR showed a mosaic arrangement and included double cones, single cones (SC), and single rods. Most cones occur as SC. The ratio between the number of cones and rods was 3:1.39 (±0.29). The rods were tall that reached the pigmented epithelium. The outer plexiform layer (OPL) showed a complex synaptic connection between the horizontal and photoreceptor terminals that were surrounded by Müller cell processes. Electron microscopy showed that the OPL possessed both cone pedicles and rod spherules. Each rod spherule consisted of a single synaptic ribbon within the invaginating terminal endings of the horizontal cell (hc) processes. In contrast, the cone pedicles possessed many synaptic ribbons within their junctional complexes. The inner nuclear layer consisted of bipolar, amacrine, Müller cells, and hc. Müller cells possessed intermediate filaments and cell processes that can reach the outer limiting membrane and form connections with each other by desmosomes. The ganglion cells were large multipolar cells with a spherical nucleus and Nissl' bodies in their cytoplasm. The presence of different types of cones arranged in a mosaic pattern in the retina of this species favors the spatial resolution of visual objects. RESEARCH HIGHLIGHTS: This is the first study demonstrating the structure and arrangement of retinal neurons of red-tail shark using light and electron microscopy. The current study showed the presence of different types of cones arranged in a mosaic pattern that may favor the spatial resolution of visual objects in this species. The bipolar, amacrine, Müller, and horizontal cells could be demonstrated.
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Affiliation(s)
- Doaa M Mokhtar
- Department of Cell and Tissues, Faculty of Vet. Medicine, Assiut University, Assiut, Egypt
- Department of Histology and Anatomy, School of veterinary medicine, Badr University in Assiut, Assiut, Egypt
| | - Alessio Alesci
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Simona Pergolizzi
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Giacomo Zaccone
- Department of Veterinary Sciences, Polo Universitario dell'Annunziata, University of Messina, Messina, Italy
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Reimchen TE, Hunter D, Eggenberger JH. Black bear colour polymorphism through a fragmented Snell’s window. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
The white colour morph of the black bear (Ursus americanus kermodei) occurring on islands on the coast of British Columbia, western Canada, captures more salmon (Oncorhynchus spp.) than does the black morph and is hypothesized to have reduced contrast against the sky from the visual perspective of the salmon. We tested this hypothesis in a natural salmon stream by recording the number and proximity of chum salmon (Oncorhynchus keta) approaches (N = 1617 fish, 91 trials) towards life-size bear models differing in body and leg coloration under a mixed forest-sky canopy. Although salmon approached the white models at a much higher rate than black models, consistent with camouflage, we found greater abrupt evasions to the black models, largely independent of their contrast against the above-surface or below-surface backgrounds. Upward-facing sub-surface video-imaging through the rippled water-air interface indicated major visual fragmentation of the model’s integrity. We suggest that increased evasiveness to black models reflects an evolutionary response due to 3+ million years of trophic interaction between salmon and bears, and that the major differences between calm vs. rippled conditions through the optical cone (Snell’s window) at the water-air interface remains a largely unexplored theme in assessing foraging preferences and adaptive coloration within and among species using the water-air interface.
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Affiliation(s)
- Thomas E Reimchen
- Department of Biology, University of Victoria, Victoria, B.C., Canada
| | - Danial Hunter
- Department of Biology, University of Victoria, Victoria, B.C., Canada
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McNerney C, Johnston RJ. Thyroid hormone signaling specifies cone photoreceptor subtypes during eye development: Insights from model organisms and human stem cell-derived retinal organoids. VITAMINS AND HORMONES 2021; 116:51-90. [PMID: 33752828 DOI: 10.1016/bs.vh.2021.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Cones are the color-detecting photoreceptors of the vertebrate eye. Cones are specialized into subtypes whose functions are determined by the expression of color-sensitive opsin proteins. Organisms differ greatly in the number and patterning of cone subtypes. Despite these differences, thyroid hormone is an important regulator of opsin expression in most vertebrates. In this chapter, we outline how the timing of thyroid hormone signaling controls cone subtype fates during retinal development. We first examine our current understanding of cone subtype specification in model organisms and then describe advances in human stem cell-derived organoid technology that identified mechanisms controlling development of the human retina.
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Affiliation(s)
- Christina McNerney
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, Baltimore, MD, United States.
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Frau S, Novales Flamarique I, Keeley PW, Reese BE, Muñoz-Cueto JA. Straying from the flatfish retinal plan: Cone photoreceptor patterning in the common sole (Solea solea) and the Senegalese sole (Solea senegalensis). J Comp Neurol 2020; 528:2283-2307. [PMID: 32103501 DOI: 10.1002/cne.24893] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/24/2020] [Accepted: 02/24/2020] [Indexed: 11/09/2022]
Abstract
The retinas of nonmammalian vertebrates have cone photoreceptor mosaics that are often organized as highly patterned lattice-like distributions. In fishes, the two main lattice-like patterns are composed of double cones and single cones that are either assembled as interdigitized squares or as alternating rows. The functional significance of such orderly patterning is unknown. Here, the cone mosaics in two species of Soleidae flatfishes, the common sole and the Senegalese sole, were characterized and compared to those from other fishes to explore variability in cone patterning and how it may relate to visual function. The cone mosaics of the common sole and the Senegalese sole consisted of single, double, and triple cones in formations that differed from the traditional square mosaic pattern reported for other flatfishes in that no evidence of higher order periodicity was present. Furthermore, mean regularity indices for single and double cones were conspicuously lower than those of other fishes with "typical" square and row mosaics, but comparable to those of goldfish, a species with lattice-like periodicity in its cone mosaic. Opsin transcripts detected by quantitative polymerase chain reaction (sws1, sws2, rh2.3, rh2.4, lws, and rh1) were uniformly expressed across the retina of the common sole but, in the Senegalese sole, sws2, rh2.4, and rh1 were more prevalent in the dorsal retina. Microspectrophotometry revealed five visual pigments in the retina of the common sole [S(472), M(523), M(536), L(559), and rod(511)] corresponding to the repertoire of transcripts quantified except for sws1. Overall, these results indicate a loss of cone mosaic patterning in species that are primarily nocturnal or dwell in low light environments as is the case for the common sole and the Senegalese sole. The corollary is that lattice-like patterning of the cone mosaic may improve visual acuity. Ecological and physiological correlates derived from observations across multiple fish taxa that live in low light environments and do not possess lattice-like cone mosaics are congruent with this claim.
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Affiliation(s)
- Sara Frau
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, The European University of the Seas (SEA-EU), Puerto Real, Spain
| | - Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.,Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Patrick W Keeley
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, USA
| | - Benjamin E Reese
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, USA.,Department of Psychological and Brain Sciences, University of California Santa Barbara, Santa Barbara, California, USA
| | - José A Muñoz-Cueto
- Department of Biology, Faculty of Marine and Environmental Sciences, University of Cádiz, The European University of the Seas (SEA-EU), Puerto Real, Spain
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Pushchin I. Retinal ganglion cell topography and spatial resolution estimation in the Japanese tree frog Hyla japonica (Günther, 1859). J Anat 2019; 235:1114-1124. [PMID: 31418464 DOI: 10.1111/joa.13075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2019] [Indexed: 11/29/2022] Open
Abstract
Tree frogs are an interesting and diverse group of frogs. They display a number of unique adaptations to life in the arboreal environment. Vision plays a crucial role in their ecology. The topography of retinal ganglion cells (GCs) is closely related to a species' visual behavior. Despite a large amount of research addressing GC topography in vertebrates, there is scarce data on this subject in tree frogs. I studied the topography of GCs in the retina of the Japanese tree frog Hyla japonica. The GC density distribution was locally fairly homogeneous, with spatial density increasing gradually from the dorsal and ventral periphery towards the equator. A moderately pronounced visual streak was found close to the equator in the dorsal hemiretina, with a distinct area retinae temporalis in the dorsotemporal quadrant potentially subserving binocular vision. The minimum GC density (mean ± SEM, n = 5) was 3060 ± 60 and the maximum 12 800 ± 170 cells/mm2 . The total number of GCs was 292 ± 7 × 103 . The theoretical anatomical spatial resolution estimated from GC densities and eye optics was lowest in the ventral periphery (ca. 0.9 and 1.3 cycles/degree in air and water, respectively) and highest in the area retinae temporalis (ca. 2.1 and 2.8 cycles/degree). The relatively high GC density and presence of specialized retinal regions in Hyla japonica are consistent with its highly visual behavior. The present findings contribute to our understanding of the relative role of common ancestry and environmental pressure in GC topography variation within Anura.
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Affiliation(s)
- Igor Pushchin
- Laboratory of Physiology, National Scientific Center of Marine Biology , Far Eastern Branch Russian Academy of Sciences, Vladivostok, Russia
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Vroman R, Kamermans M. Feedback-induced glutamate spillover enhances negative feedback from horizontal cells to cones. J Physiol 2015; 593:2927-40. [PMID: 25820622 DOI: 10.1113/jp270158] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 03/24/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In the retina, horizontal cells feed back negatively to cone photoreceptors. Glutamate released from cones can spill over to neighbouring cones. Here we show that cone glutamate release induced by negative feedback can also spill over to neighbouring cones. This glutamate activates the glutamate transporter-associated chloride current in these neighbouring cones, which leads to a change in their membrane potential and thus modulates their output. In this way, feedback-induced glutamate spillover enhances negative feedback from horizontal cells to cones, thus forming an additional feedback pathway. This effect will be particularly prominent in cones that are strongly hyperpolarized by light. ABSTRACT Inhibition in the outer retina functions via an unusual mechanism. When horizontal cells hyperpolarize the activation potential of the Ca(2+) current of cones shifts to more negative potentials. The underlying mechanism consists of an ephaptic component and a Panx1/ATP-mediated component. Here we identified a third feedback component, which remains active outside the operating range of the Ca(2+) current. We show that the glutamate transporters of cones can be activated by glutamate released from their neighbours. This pathway can be triggered by negative feedback from horizontal cells to cones, thus providing an additional feedback pathway. This additional pathway is mediated by a Cl(-) current, can be blocked by either removing the gradient of K(+) or by adding the glutamate transporter blocker TBOA, or low concentrations of Zn(2+) . These features point to a glutamate transporter-associated Cl(-) current. The pathway has a delay of 4.7 ± 1.7 ms. The effectiveness of this pathway in modulating the cone output depends on the equilibrium potential of Cl(-) (ECl ) and the membrane potential of the cone. Because estimates of ECl show that it is around the dark resting membrane potential of cones, the activation of the glutamate transporter-associated Cl(-) current will be most effective in changing the membrane potential during strong hyperpolarization of cones. This means that negative feedback would particularly be enhanced by this pathway when cones are hyperpolarized. Spatially, this pathway does not reach further than the direct neighbouring cones. The consequence is that this feedback pathway transmits information between cones of different spectral type.
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Affiliation(s)
- Rozan Vroman
- Retinal Signal Processing Lab, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands
| | - Maarten Kamermans
- Retinal Signal Processing Lab, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands.,Department of Neurogenetics, University of Amsterdam, Academic Medical Centre, Meibergdreef 15, 1105 AZ, Amsterdam, Netherlands
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Suliman T, Novales Flamarique I. Visual pigments and opsin expression in the juveniles of three species of fish (rainbow trout, zebrafish, and killifish) following prolonged exposure to thyroid hormone or retinoic acid. J Comp Neurol 2014; 522:98-117. [PMID: 23818308 DOI: 10.1002/cne.23391] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 06/05/2013] [Accepted: 06/19/2013] [Indexed: 02/02/2023]
Abstract
Thyroid hormone (TH) and retinoic acid (RA) are powerful modulators of photoreceptor differentiation during vertebrate retinal development. In the embryos and young juveniles of salmonid fishes and rodents, TH induces switches in opsin expression within individual cones, a phenomenon that also occurs in adult rodents following prolonged (12 week) hypothyroidism. Whether changes in TH levels also modulate opsin expression in the differentiated retina of fish is unknown. Like TH, RA is essential for retinal development, but its role in inducing opsin switches, if any, has not been studied. Here we investigate the action of TH and RA on single-cone opsin expression in juvenile rainbow trout, zebrafish, and killifish and on the absorbance of visual pigments in rainbow trout and zebrafish. Prolonged TH exposure increased the wavelength of maximum absorbance (λmax ) of the rod and the medium (M, green) and long (L, red) wavelength visual pigments in all fish species examined. However, unlike the opsin switch that occurred following TH exposure in the single cones of small juvenile rainbow trout (alevin), opsin expression in large juvenile rainbow trout (smolt), zebrafish, or killifish remained unchanged. RA did not induce any opsin switches or change the visual pigment absorbance of photoreceptors. Neither ligand altered cone photoreceptor densities. We conclude that RA has no effect on opsin expression or visual pigment properties in the differentiated retina of these fishes. In contrast, TH affected both single-cone opsin expression and visual pigment absorbance in the rainbow trout alevin but only visual pigment absorbance in the smolt and in zebrafish. The latter results could be explained by a combination of opsin switches and chromophore shifts from vitamin A1 to vitamin A2.
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Affiliation(s)
- Tarek Suliman
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
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8
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Newman AS, Marshall JN, Collin SP. Visual Eyes: A Quantitative Analysis of the Photoreceptor Layer in Deep-Sea Sharks. BRAIN, BEHAVIOR AND EVOLUTION 2013; 82:237-49. [DOI: 10.1159/000355370] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 08/22/2013] [Indexed: 11/19/2022]
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Flamarique IN, Cheng CL, Bergstrom C, Reimchen TE. Pronounced heritable variation and limited phenotypic plasticity in visual pigments and opsin expression of threespine stickleback photoreceptors. ACTA ACUST UNITED AC 2012; 216:656-67. [PMID: 23077162 DOI: 10.1242/jeb.078840] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Vertebrate colour vision is mediated by the differential expression of visual pigment proteins (opsins) in retinal cone photoreceptors. Many species alter opsin expression during life, either as part of development or as a result of changes in habitat. The latter, a result of phenotypic plasticity, appears common among fishes, but its cellular origin and ecological significance are unknown. Here, we used adult threespine stickleback fish from different photic regimes to investigate heritable variability and phenotypic plasticity in opsin expression. Fish from clear waters had double cones that expressed long (LWS) and middle (RH2) wavelength opsins, one per double cone member. In contrast, fish from red light-shifted lakes had double cones that were >95% LWS/LWS pairs. All fish had single cones that predominantly expressed a short wavelength (SWS2) opsin but ultraviolet cones, expressing a SWS1 opsin, were present throughout the retina. Fish from red light-shifted lakes, when transferred to clear waters, had a ∼2% increase in RH2/LWS double cones, though double cone density remained constant. Comparison of visual pigment absorbance and light transmission in the environment indicated that the opsin complements of double cones maximized sensitivity to the background light, whereas single cones had visual pigments that were spectrally offset from the dominant background wavelengths. Our results indicate that phenotypic plasticity in opsin expression is minor in sticklebacks and of questionable functional significance.
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Novales Flamarique I. Unique photoreceptor arrangements in a fish with polarized light discrimination. J Comp Neurol 2011; 519:714-37. [DOI: 10.1002/cne.22544] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Hawryshyn CW, Ramsden SD, Betke KM, Sabbah S. Spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar): phylogenetic considerations. ACTA ACUST UNITED AC 2010; 213:3187-97. [PMID: 20802121 DOI: 10.1242/jeb.038760] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We were interested in comparing the characteristics of polarization sensitivity in Atlantic salmon to those in Pacific salmon. Here we show that the common ancestor to the clade containing Salmo salar, Oncorhynchus mykiss, O. nerka, O. clarkii and Salvelinus fontinalis has the trait of ultraviolet polarization sensitivity. We examined spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar) using both optic nerve compound action potential (CAP) and electroretinogram (ERG) recordings. Our experiments employed photic manipulation to adjust the sensitivity of the four cone mechanisms of Atlantic salmon. A spectrally broad background was used to ensure a contribution of all cone mechanisms to both spectral and polarization sensitivity. Chromatic adaptation was used to isolate the sensitivity of each of the four cone mechanisms for both spectral and polarization sensitivity. Under spectrally broad conditions, UV sensitive (UVS), mid wavelength sensitive (MWS) and long wavelength sensitive (LWS) cone mechanisms contributed to polarization sensitivity. CAP recordings produced the typical 'W' shaped polarization sensitivity curve reflecting two active polarization detectors with peaks at e-vector orientations of 0 deg, 90 deg and 180 deg, and troughs at 30 deg and 150 deg. ERG recordings produced a four-peaked polarization sensitivity curve reflecting two active polarization detectors and negative feedback activity, with peaks at e-vectors 0 deg, 45 deg, 90 deg, 135 deg and 180 deg, and troughs at 30 deg, 60 deg, 120 deg and 150 deg. Polarization-sensitivity measurements of isolated cone mechanisms revealed two orthogonal polarization detector mechanisms in Atlantic salmon, identical to that found in rainbow trout and other Pacific salmonid fishes. Moreover, under spectrally broad background conditions, CAP and ERG polarization sensitivity of Atlantic salmon did not differ significantly from that reported in Pacific salmonids.
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Affiliation(s)
- C W Hawryshyn
- Department of Biology and Center for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Koch PC, Seebacher C, Heß M. 3D-topography of cell nuclei in a vertebrate retina—A confocal and two-photon microscopic study. J Neurosci Methods 2010; 188:127-40. [DOI: 10.1016/j.jneumeth.2010.01.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Accepted: 01/23/2010] [Indexed: 10/19/2022]
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HOFMANN CHRISTOPHERM, O’QUIN KELLYE, SMITH ADAMR, CARLETON KARENL. Plasticity of opsin gene expression in cichlids from Lake Malawi. Mol Ecol 2010; 19:2064-74. [DOI: 10.1111/j.1365-294x.2010.04621.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hofmann CM, Carleton KL. Gene duplication and differential gene expression play an important role in the diversification of visual pigments in fish. Integr Comp Biol 2009; 49:630-43. [DOI: 10.1093/icb/icp079] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Morphological changes in the retina in Pacific ocean salmon Oncorhynchus masou fry in response to neutralization of the geomagnetic field in conditions of normal illumination. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2008; 38:821-7. [PMID: 18802765 DOI: 10.1007/s11055-008-9054-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 03/06/2007] [Indexed: 10/21/2022]
Abstract
The studies reported here provide the first demonstration that retinal responses in both the fry of the migratory salmon trout Oncorhynchus masou and the dwarf form of this species changed in conditions of experimental neutralization of the geomagnetic field (GMF); migratory salmon trout fry and dwarves showed different changes. The responses of different types of retinal photoreceptor in migratory salmon trout fry to neutralization of the GMF differed: while rods and double cones perceived neutralization of the GMF as the onset of darkness (the scotopic reaction), single (generally blue-sensitive) cones responded to neutralization of the GMF both as presentation of blue light or (very rarely) ultraviolet irradiation. The retina of dwarf male salmon trout responded to neutralization of the GMF with a double response: rods showed a light (photopic) response, while double (red/green-sensitive) cones produced dark (scotopic) responses. Single (blue-sensitive) cones responded to neutralization of the GMF as bright blue light. Thus, the morphological picture of the retina in dwarf male salmon trout in these experimental conditions corresponds to the perception of blue light. The initial conditions were different--normal diffuse daylight with a brightness of about 7.5 Lx. It is likely that neutralization of the magnetic field had no effect on rods, while double, red-green, cones responded as to darkness, i.e., the fish did not perceive red or green light in the visible spectrum, but perceived only blue and, possibly, ultraviolet light by means of central blue-sensitive and accessory cones. Thus, these experiments demonstrated that in conditions of normal daylight illumination, retinal photoreceptors in salmon fry respond to changes in the earth's magnetic field, i.e., objectively function as magnetoreceptors.
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Temple SE, Ramsden SD, Haimberger TJ, Veldhoen KM, Veldhoen NJ, Carter NL, Roth WM, Hawryshyn CW. Effects of exogenous thyroid hormones on visual pigment composition in coho salmon (Oncorhynchus kisutch). ACTA ACUST UNITED AC 2008; 211:2134-43. [PMID: 18552303 DOI: 10.1242/jeb.009365] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of exogenous thyroid hormone on visual pigment content of rod and cone photoreceptors was investigated in coho salmon (Oncorhynchus kisutch). Coho vary the ratio of vitamin A1- and A2-based visual pigments in their eyes. This variability potentially alters spectral sensitivity and thermal stability of the visual pigments. We tested whether the direction of shift in the vitamin A1/A2 ratio, resulting from application of exogenous thyroid hormone, varied in fish of different ages and held under different environmental conditions. Changes in the vitamin A1/A2 visual pigment ratio were estimated by measuring the change in maximum absorbance (lambda max) of rods using microspectrophotometry (MSP). Exogenous thyroid hormone resulted in a long-wavelength shift in rod, middle-wavelength-sensitive (MWS) and long-wavelength-sensitive (LWS) cone photoreceptors. Rod and LWS cone lambda max values increased, consistent with an increase in vitamin A2. MWS cone lambda max values increased more than predicted for a change in the vitamin A1/A2 ratio. To account for this shift, we tested for the expression of multiple RH2 opsin subtypes. We isolated and sequenced a novel RH2 opsin subtype, which had 48 amino acid differences from the previously sequenced coho RH2 opsin. A substitution of glutamate for glutamine at position 122 could partially account for the greater than predicted shift in MWS cone lambda max values. Our findings fit the hypothesis that a variable vitamin A1/A2 ratio provides seasonality in spectral tuning and/or improved thermal stability of visual pigments in the face of seasonal environmental changes, and that multiple RH2 opsin subtypes can provide flexibility in spectral tuning associated with migration-metamorphic events.
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Affiliation(s)
- Shelby E Temple
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
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Carleton KL, Spady TC, Streelman JT, Kidd MR, McFarland WN, Loew ER. Visual sensitivities tuned by heterochronic shifts in opsin gene expression. BMC Biol 2008; 6:22. [PMID: 18500997 PMCID: PMC2430543 DOI: 10.1186/1741-7007-6-22] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 05/23/2008] [Indexed: 11/11/2022] Open
Abstract
Background Cichlid fishes have radiated into hundreds of species in the Great Lakes of Africa. Brightly colored males display on leks and vie to be chosen by females as mates. Strong discrimination by females causes differential male mating success, rapid evolution of male color patterns and, possibly, speciation. In addition to differences in color pattern, Lake Malawi cichlids also show some of the largest known shifts in visual sensitivity among closely related species. These shifts result from modulated expression of seven cone opsin genes. However, the mechanisms for this modulated expression are unknown. Results In this work, we ask whether these differences might result from changes in developmental patterning of cone opsin genes. To test this, we compared the developmental pattern of cone opsin gene expression of the Nile tilapia, Oreochromis niloticus, with that of several cichlid species from Lake Malawi. In tilapia, quantitative polymerase chain reaction showed that opsin gene expression changes dynamically from a larval gene set through a juvenile set to a final adult set. In contrast, Lake Malawi species showed one of two developmental patterns. In some species, the expressed gene set changes slowly, either retaining the larval pattern or progressing only from larval to juvenile gene sets (neoteny). In the other species, the same genes are expressed in both larvae and adults but correspond to the tilapia adult genes (direct development). Conclusion Differences in visual sensitivities among species of Lake Malawi cichlids arise through heterochronic shifts relative to the ontogenetic pattern of the tilapia outgroup. Heterochrony has previously been shown to be a powerful mechanism for change in morphological evolution. We found that altering developmental expression patterns is also an important mechanism for altering sensory systems. These resulting sensory shifts will have major impacts on visual communication and could help drive cichlid speciation.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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Cheng CL, Flamarique IN. Chromatic organization of cone photoreceptors in the retina of rainbow trout: single cones irreversibly switch from UV (SWS1) to blue (SWS2) light sensitive opsin during natural development. J Exp Biol 2007; 210:4123-35. [DOI: 10.1242/jeb.009217] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARYThe retinas of salmonid fishes have single and double cones arranged in square to row formations termed mosaics. The square mosaic unit is formed by four double cones that make the sides of the square with a single (centre)cone in the middle, and a single (corner) cone at each corner of the square when present. Previous research using coho salmon-derived riboprobes on four species of anadromous Pacific salmon has shown that all single cones express a SWS1 (UV sensitive) visual pigment protein (opsin) at hatching, and that these cones switch to a SWS2 (blue light sensitive) opsin during the juvenile period. Whether this opsin switch applies to non-anadromous species, like the rainbow trout, is under debate as species-specific riboprobes have not been used to study opsin expression during development of a trout. As well, a postulated recovery of SWS1 opsin expression in the retina of adult rainbow trout, perhaps via a reverse process to that occurring in the juvenile, has not been investigated. Here, we used in situhybridization with species-specific riboprobes and microspectrophotometry on rainbow trout retina to show that: (1) single cones in the juvenile switch opsin expression from SWS1 to SWS2, (2) this switch is not reversed in the adult, i.e. all single cones in the main retina continue to express SWS2 opsin, and (3) opsin switches do not occur in double cones: each member expresses one opsin, maximally sensitive to green (RH2) or red (LWS) light. The opsin switch in the single cones of salmonid fishes may be a general process of chromatic organization that occurs during retinal development of most vertebrates.
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Affiliation(s)
- Christiana L. Cheng
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada, V5A 1S6
| | - Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada, V5A 1S6
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Cheng CL, Flamarique IN. Photoreceptor distribution in the retina of adult Pacific salmon: corner cones express blue opsin. Vis Neurosci 2007; 24:269-76. [PMID: 17592670 DOI: 10.1017/s0952523807070137] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 01/29/2007] [Indexed: 11/06/2022]
Abstract
The retina of salmonid fishes has two types of cone photoreceptors: single and double cones. At the nuclear level, these cones are distributed in a square mosaic such that the double cones form the sides of the square and the single cones occupy positions at the centre and at the corners of the square. Double cones consist of two members, one having visual pigment protein maximally sensitive to green light (RH2 opsin), the other maximally sensitive to red light (LWS opsin). Single cones can have opsins maximally sensitive to ultraviolet (UV) or blue light (SWS1 and SWS2 opsins, respectively). In Pacific salmonids, all single cones express UV opsin at hatching. Around the time of yolk sac absorption, single cones start switching opsin expression from UV to blue, in an event that proceeds from the ventral to the dorsal retina. This transformation is accompanied by a loss of single corner cones such that the large juvenile shows corner cones and UV opsin expression in the dorsal retina only. Previous research has shown that adult Pacific salmon have corner cones over large areas of retina suggesting that these cones may be regenerated and that they may express UV opsin. Here we used in-situ hybridization with cRNA probes and RT-PCR to show that: (1) all single cones in non-growth zone areas of the retina express blue opsin and (2) double cone opsin expression alternates around the square mosaic unit. Our results indicate that single cone driven UV sensitivity in adult salmon must emanate from stimulation of growth zone areas.
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Affiliation(s)
- Christiana L Cheng
- Department of Biological Sciences, Simon Fraser University, British Columbia, Canada
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20
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Abstract
The retinas of teleost fish have long been of interest to developmental neurobiologists for their persistent plasticity during growth, life history changes, and response to injury. Because the vertebrate retina is a highly conserved tissue, the study of persistent plasticity in teleosts has provided insights into mechanisms for postembryonic retinal neurogenesis in mammals. In addition, in the past 10 years there has been an explosion in the use of teleost fish-zebrafish (Danio rerio) in particular-to understand the mechanisms of embryonic retinal neurogenesis in a model vertebrate with genetic resources. This review summarizes the key features of teleost retinal neurogenesis that make it a productive and interesting experimental system, and focuses on the contributions to our knowledge of retinal neurogenesis that uniquely required or significantly benefited from the use of a fish model system.
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Affiliation(s)
- Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844, USA
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Allison WT, Hallows TE, Johnson T, Hawryshyn CW, Allen DM. Photic history modifies susceptibility to retinal damage in albino trout. Vis Neurosci 2006; 23:25-34. [PMID: 16597348 DOI: 10.1017/s0952523806231031] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Accepted: 09/29/2005] [Indexed: 11/07/2022]
Abstract
Albino vertebrates exposed to intense light typically lose photoreceptors via apoptosis, and thus serve as useful models of retinal degeneration. In contrast, albino rainbow trout exposed to intense light maintain populations of rod and cone nuclei despite substantial damage to rod outer segments (ROS). The aim of this study was to differentiate between two hypotheses that could account for this divergent result: (1) trout rod nuclei remain intact during light damage, or (2) rod nuclei die but are replaced by cell proliferation. A further aim was to examine whether photic history modulates retinal damage, as in rodents. Albino and normally pigmented trout were moved from defined photic regimes into full daylight, while some were not moved to serve as protected controls. ROS were always maintained in pigmented fish and in albinos protected from full daylight. In albinos exposed to full daylight, ROS were removed over most of the central retina, whereas rod nuclei were maintained in the outer nuclear layer over 10 days. Pyknotic and TUNEL-labeled rod nuclei were abundant in affected albinos at all time-points tested. Rod death occurred without a decrease in the number of rod nuclei, confirming that proliferation must be replacing cells. Indeed a transient increase in proliferation was observed in retinal progenitors of albinos receiving 5 days of damaging light. This proliferative response was decreased with further damage. Cones remained intact even in areas where rod nuclei had degenerated. Pretreatment with light of moderate versus low intensity light affected the cell death and proliferative responses, and the ectopic localization of rod opsin. We conclude that apoptotic demise of rods, but not cones, occurred during light damage in retinas of albino trout and proliferative responses have a limited a capacity to replace lost rods.
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Affiliation(s)
- W Ted Allison
- The University of Michigan, Department of Molecular, Cellular, and Developmental Biology, Ann Arbor, Michigan, USA
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Veldhoen K, Allison WT, Veldhoen N, Anholt BR, Helbing CC, Hawryshyn CW. Spatio-temporal characterization of retinal opsin gene expression during thyroid hormone-induced and natural development of rainbow trout. Vis Neurosci 2006; 23:169-79. [PMID: 16638170 DOI: 10.1017/s0952523806232139] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 02/04/2006] [Indexed: 11/07/2022]
Abstract
The abundance and spatial distribution of retinal cone photoreceptors change during thyroid hormone (TH)-induced and natural development of rainbow trout (Oncorhynchus mykiss). These changes are thought to allow the fish to adapt to different photic environments throughout its life history. To date, the ontogeny of rainbow trout cone photoreceptors has been examined using physiological and morphological approaches. In this study, we extended these observations by measuring opsin gene expression in retinal quadrants during natural and TH-induced development. Gene expression during natural development was investigated in retinae from fish at both parr and smolt stages. The role of TH in modulating opsin gene expression was determined in TH-treated parr and control fish sampled after two, nine, and 22 days of treatment. Total RNA was isolated from each retinal quadrant and steady-state opsin mRNA levels were measured using reverse transcriptase real-time quantitative polymerase chain reaction (QPCR) analysis. Expression of ultraviolet-sensitive opsin (SWS1), rod opsin (RH1), middle wavelength-sensitive opsin (RH2), and long wavelength-sensitive opsin (LWS) transcripts vary spatially in the parr retina. Smolts, compared to parr, had downregulated SWS1 expression in all quadrants, lower LWS expression dorsally, higher RH1 expression nasally, and higher RH2 expression dorsally. In TH-treated parr, SWS1 opsin expression was downregulated in the nasal quadrants by two days. SWS1 displayed the greatest degree of downregulation in all quadrants after nine days of treatment, with an increase in short wavelength-sensitive (SWS2) and RH2 opsin mRNA expression in the temporal quadrants. This study reveals that opsin genes display spatially significant differences within rainbow trout retina in their level of mRNA expression, and that regulation of opsin expression is a dynamic process that is influenced by TH. This is particularly evident for SWS1 gene expression in parr following TH-induced and natural development.
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Affiliation(s)
- Kathy Veldhoen
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
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Cheng CL, Flamarique IN, Hárosi FI, Rickers-Haunerland J, Haunerland NH. Photoreceptor layer of salmonid fishes: Transformation and loss of single cones in juvenile fish. J Comp Neurol 2006; 495:213-35. [PMID: 16435286 DOI: 10.1002/cne.20879] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The retinas of many vertebrates have cone photoreceptors that express multiple visual pigments. In many of these animals, including humans, the original cones to appear in the retina (which express UV or blue opsin) may change opsin types, giving rise to new spectral phenotypes. Here we used microspectrophotometry and in situ hybridization with cDNA probes to study the distribution of UV and blue cones in the retinas of four species of Pacific salmon (coho, chum, chinook, and pink salmon), in the Atlantic salmon, and in the rainbow/steelhead trout. In Pacific salmon and in the trout, all single cones express a UV opsin at hatching (lambda(max) of the visual pigment approximately 365 nm), and these cones later transform into blue cones by opsin changeover (lambda(max) of the blue visual pigment approximately 434 nm). Cones undergoing UV opsin downregulation exhibit either of two spectral absorbance profiles. The first is characterized by UV and blue absorbance peaks, with blue absorbance dominating the base of the outer segment. The second shows UV absorbance diminishing from the outer segment tip to the base, with no sign of blue absorbance. The first absorbance profile indicates a transformation from UV to blue phenotype by opsin changeover, while the second type suggests that the cone is undergoing apoptosis. These two events (transformation and loss of corner cones) are closely associated in time and progress from ventral to dorsal retina. Each double cone member contains green (lambda(max) approximately 510 nm) or red (lambda(max) approximately 565 nm) visual pigment (double cones are green/red pairs), and, like the rods (lambda(max) approximately 508 nm), do not exhibit opsin changeover. Unlike Pacific salmonids, the Atlantic salmon shows a mixture of UV and blue cones and a partial loss of corner cones at hatching. This study establishes the UV-to-blue cone transformation as a general feature of retinal growth in Pacific salmonids (genus Oncorhynchus).
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Affiliation(s)
- Christiana L Cheng
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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Bailes HJ, Robinson SR, Trezise AEO, Collin SP. Morphology, characterization, and distribution of retinal photoreceptors in the Australian lungfish Neoceratodus forsteri (Krefft, 1870). J Comp Neurol 2006; 494:381-97. [PMID: 16320259 DOI: 10.1002/cne.20809] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Australian lungfish Neoceratodus forsteri (Dipnoi) is an ancient fish that has a unique phylogenetic relationship among the basal Sarcopterygii. Here we examine the ultrastructure, histochemistry, and distribution of the retinal photoreceptors using a combination of light and electron microscopy in order to determine the characteristics of the photoreceptor layer in this living fossil. Similar proportions of rods (53%) and cones (47%) reveal that N. forsteri optimizes both scotopic and photopic sensitivity according to its visual demands. Scotopic sensitivity is optimized by a tapetum lucidum and extremely large rods (18.62 +/- 2.68 microm ellipsoid diameter). Photopic sensitivity is optimized with a theoretical spatial resolving power of 3.28 +/- 0.66 cycles degree(-1), which is based on the spacing of at least three different cone types: a red cone containing a red oil droplet, a yellow cone containing a yellow ellipsoidal pigment, and a colorless cone containing multiple clear oil droplets. Topographic analysis reveals a heterogeneous distribution of all photoreceptor types, with peak cone densities predominantly found in temporal retina (6,020 rods mm(-2), 4,670 red cones mm(-2), 900 yellow cones mm(-2), and 320 colorless cones mm(-2)), but ontogenetic changes in distribution are revealed. Spatial resolving power and the diameter of all photoreceptor types (except yellow cones) increases linearly with growth. The presence of at least three morphological types of cones provides the potential for color vision, which could play a role in the clearer waters of its freshwater environment.
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Affiliation(s)
- Helena J Bailes
- School of Biomedical Sciences, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia.
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25
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Allison WT, Dann SG, Veldhoen KM, Hawryshyn CW. Degeneration and regeneration of ultraviolet cone photoreceptors during development in rainbow trout. J Comp Neurol 2006; 499:702-15. [PMID: 17048226 DOI: 10.1002/cne.21164] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ultraviolet-sensitive (UVS) cones disappear from the retina of salmonid fishes during a metamorphosis that prepares them for deeper/marine waters. UVS cones subsequently reappear in the retina near sexual maturation and the return migration to natal streams. Cellular mechanisms of this UVS cone ontogeny were investigated using electroretinograms, in situ hybridization, and immunohistochemistry against opsins during and after thyroid hormone (TH) treatments of rainbow trout (Oncorhynchus mykiss). Increasing TH levels led to UVS cone degeneration. Labeling demonstrated that UVS cone degeneration occurs via programmed cell death and caspase inhibitors can inhibit this death. After the cessation of TH treatment, UVS cones regenerated in the retina. Bromodeoxyuridine (BrdU) was applied after the termination of TH treatment and was detected in the nuclei of cells expressing UVS opsin. BrdU was found in UVS cones but not other cone types. The most parsimonious explanation for the data is that UVS cones degenerated and UVS cones were regenerated from intrinsic retinal progenitor cells. Regenerating UVS cones were functionally integrated such that they were able to elicit electrical responses from second-order neurons. This is the first report of cones regenerating during natural development. Both the death and regeneration of cones in retinae represent novel mechanisms for tuning visual systems to new visual tasks or environments.
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Affiliation(s)
- W Ted Allison
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
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27
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Candal E, Anadón R, DeGrip WJ, Rodríguez-Moldes I. Patterns of cell proliferation and cell death in the developing retina and optic tectum of the brown trout. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 154:101-19. [PMID: 15617760 DOI: 10.1016/j.devbrainres.2004.10.008] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/10/2004] [Indexed: 10/26/2022]
Abstract
We have analyzed the patterns of cell proliferation and cell death in the retina and optic tectum of the brown trout (Salmo trutta fario) throughout embryonic and postembryonic stages. Cell proliferation was detected by immunohistochemistry with an antibody against the proliferating cell nuclear antigen (PCNA), and apoptosis by means of the TUNEL method. Haematoxylin and DAPI staining were also used to demonstrate apoptotic cells. Photoreceptor cell differentiation was assessed by immunohistochemistry with antibodies against opsins. Throughout embryonic development, PCNA-immunoreactive (PCNA-ir) cells become progressively restricted to the peripheral growth zone of the retina, which appears to be the principal source of new retinal cells from late embryos to adults. However, some PCNA-ir cells are observed secondarily in the differentiated retina, first in the inner nuclear layer of 15-mm alevins and later in the outer nuclear layer of 16-mm alevins, after differentiation of the first rods in the central retina, as demonstrated with opsin immunocytochemistry. Our observations also support the view that the PCNA-ir cells observed secondarily in the INL of the central retina of alevins are photoreceptor precursors. The number and distribution of apoptotic cells in the retina and optic tectum of the trout change throughout development, allowing distinction of several waves of apoptosis. Cell death is detected in proliferating areas at early stages, then in postmitotic or differentiating areas, and later concurring temporal and spatially with the establishment of visual circuits, thus indicating a relationship between apoptosis and proliferation, differentiation and synaptogenesis.
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Affiliation(s)
- Eva Candal
- Department of Cell Biology and Ecology, Faculty of Biology, University of Santiago de Compostela, 15782-Santiago de Compostela, Spain
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28
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Hawryshyn CW, Martens G, Allison WT, Anholt BR. Regeneration of ultraviolet-sensitive cones in the retinal cone mosaic of thyroxin-challenged post-juvenile rainbow trout (Oncorhynchus mykiss). J Exp Biol 2003; 206:2665-73. [PMID: 12819272 DOI: 10.1242/jeb.00470] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previous studies in our laboratory have examined the loss of ultraviolet-sensitive (UVS) cones and UV sensitivity. This study looks at the question of regeneration of UVS cones and its topographic distribution, along with several other measures of the cone mosaic. Topography of the cone mosaic in rainbow trout smolts (post-metamorphic juveniles) was examined under normal growth conditions and during an exogenous thyroid hormone (TH) challenge. Growth of trout retina was studied over six weeks. Retinas sampled at 0, 3 and 6 weeks were embedded in EPON resin, and thick (1 micro m) tangential sections were stained with Richardson's stain. Sites representing central ventral, ventral, temporal, dorsal and nasal retina were sampled. Variables measured were cone densities, mean double cone diameter and mean spacing between cones of the same type. These same variables were compared with those of fish that were challenged with L-thyroxin (T4), and regeneration of UVS cones was assessed. Principal components of the correlation matrix of all photoreceptor measurements were analysed using analysis of variance. Here, we show several interesting effects of thyroxin exposure on post-metamorphic rainbow trout: (1) controls at week 0 have a high density of UVS cones in the temporal and dorsal sampling regions and a high density of blue (short-wavelength)-sensitive (SWS) and double cones across all regions sampled; (2) both control and TH-treated fish had less abundant, larger and less tightly packed SWS and double cones and a lower density of UVS cones in the temporal and dorsal sampling regions three and six weeks into the experiment compared with the starting condition at week 0; (3) fish treated with TH had a higher UVS cone density in the nasal and ventral sampling regions and there were higher densities of SWS and double cones in the central ventral, temporal and ventral regions, but lower densities in the nasal sampling regions, relative to the controls. The regeneration of UVS cones into the ventral retinal hemisphere in post-juvenile salmonids has important implications for visually guided behavior.
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Affiliation(s)
- Craig W Hawryshyn
- Department of Biology, University of Victoria, PO Box 3020 Stn. CSC, Victoria, British Columbia, Canada V8W 3N5.
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29
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Allison WT, Dann SG, Helvik JV, Bradley C, Moyer HD, Hawryshyn CW. Ontogeny of ultraviolet-sensitive cones in the retina of rainbow trout (Oncorhynchus mykiss). J Comp Neurol 2003; 461:294-306. [PMID: 12746869 DOI: 10.1002/cne.10682] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In order to facilitate emerging models of retinal development, we developed electroretinogram and in situ hybridization protocols to examine the ontogeny of photoreceptors in the retina of a land-locked salmonid, the rainbow trout (Oncorhynchus mykiss). We cloned cDNA fragments corresponding to the rod opsin and each of the four cone opsin gene families, which we utilized to produce riboprobes. We established the specificity of the in situ hybridization protocol by examining subcellular signal localization and through double-labeling experiments. We confirm the assumption that the accessory corner cones in the square mosaic are the ultraviolet wavelength-sensitive (UVS) cone photoreceptor (i.e., they express an SWS1 opsin) and observed UVS cones throughout the retina of small trout. Larger fish have a decrease in sensitivity to short wavelength light stimuli and the distribution of UVS cones in the mature retina is limited to the dorsal-temporal quadrant. These larger fish also possess differentiated UVS cones in the peripheral germinal zone (PGZ), including within areas peripheral to mature retina lacking UVS cones. These data are consistent with the loss of putative UVS cones from the PGZ of a migratory salmonid of another genus, and thus the disappearance of UVS cones appears to be general to the Family Salmonidae, regardless of life history strategy. The generation, differentiation, and subsequent loss of UVS cones in the smolt PGZ is a dramatic example of the supposition that the mechanisms of PGZ development recapitulate the retinal embryogenesis of that species.
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Affiliation(s)
- W Ted Allison
- Department of Biology, University of Victoria, Victoria, British Columbia V8W 3N5, Canada
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30
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Parkyn DC, Austin JD, Hawryshyn CW. Acquisition of polarized-light orientation in salmonids under laboratory conditions. Anim Behav 2003. [DOI: 10.1006/anbe.2003.2136] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Novales Flamarique I. Partial re-incorporation of corner cones in the retina of the Atlantic salmon (Salmo salar). Vision Res 2002; 42:2737-45. [PMID: 12450493 DOI: 10.1016/s0042-6989(02)00360-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The distribution of corner (putative ultraviolet-sensitive) cones in the retina of Atlantic salmon was examined from the small juvenile (parr) stage to the adult stage (approaching sexual maturation). Small parr weighing approximately 5 g lacked corner cones everywhere except, mainly, near the dorsal periphery. Large fish ( approximately 5 kg) approaching sexual maturation showed corner cones in other areas of the dorsal retina besides the periphery. These areas, characterized by low resolving power, had similar corner cone densities to analogous areas in the smolt retina, suggesting that corner cones are formed in the periphery and incorporated into the dorsal retina of the Atlantic salmon sometime during the smolt stage. This incorporation is partial both in numbers of cones and in location (only the dorsal retina is affected). These findings contrast with the situation in rainbow trout where corner cones from existing mosaics are only partially lost from the ventral retina, if at all, and where production and incorporation of these cones into the dorsal retina occurs throughout life. Thus, in salmonids, there are at least two different strategies that determine retinal corner cone distributions.
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Affiliation(s)
- Iñigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, BC, V5A 1S6, Burnaby, Canada.
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Miyazaki T, Iwami T, Somiya H, Meyer-Rochow VB. Retinal topography of ganglion cells and putative UV-sensitive cones in two Antarctic fishes: Pagothenia borchgrevinki and Trematomus bernacchii (Nototheniidae). Zoolog Sci 2002; 19:1223-9. [PMID: 12499665 DOI: 10.2108/zsj.19.1223] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Accessory corner cones (ACC) have recently been suggested to be UV-sensitive photoreceptor cells. With a view toward explaining prey detection, we examined the topography of retinal ganglion cells and ACCs in two Antarctic nototheniids occupying different ecological niches: the cryopelagic Pagothenia borchgrevinki and the benthic Trematomus bernacchii. Isodensity maps of retinal ganglion cells showed that the main visual axis, coincident with the feeding vector, was in a forward direction in both species. Visual acuity was determined as 3.64 and 4.77 cycles/degree for the respective species. In P. borchgrevinki the highest density of ACCs was associated with the eye's main visual axis. This suggested that this species uses UV-vision during forward-swims and probably in encounters with prey. On the other hand, T. bernacchii possessed two horizontal band-shaped high-density areas of ACCs, which stretched from temporal to nasal and ventral to peripheral retinal regions. Therefore, this species appears to use UV-vision to watch prey across the entire circumference of the lateral area and in the water column above its head.
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Affiliation(s)
- Taeko Miyazaki
- Department of Radiation Protection and Safety, National Institute of Radiological Sciences, Ibaraki, Japan.
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Faillace MP, Julian D, Korenbrot JI. Mitotic activation of proliferative cells in the inner nuclear layer of the mature fish retina: regulatory signals and molecular markers. J Comp Neurol 2002; 451:127-41. [PMID: 12209832 DOI: 10.1002/cne.10333] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
New neurons continuously differentiate within the otherwise mature retina of teleost fish, both under normal conditions and in response to injury. We investigated the effects of surgical injury and intraocular injection of neurotrophic factors on the mitotic rate of proliferative inner nuclear layer cells (PINC). PINC are continually born in the inner nuclear layer and then migrate to the outer nuclear layer (ONL). Surgical excision of a part of a retina activates PINC mitotic activity near and far from the lesion. In the injured eye, up-regulation of PINC cells is largest in the dorsonasal sector of the retina, regardless of the site of lesion. Up-regulation extends even to the unlesioned contralateral eye, where it occurs in the same dorsonasal sector. Intraocular injection of ciliary neurotrophic factor mimics the effect of injury on PINC in the treated eye but not on the untreated contralateral retina. We searched for the expression in PINC of Pax6, a transcription factor linked to retinal progenitor cells and found that less than 0.5% of all PINC cells express it. Importantly, the number of Pax6-expressing PINC does not change significantly in the retinas subjected to any of the experimental manipulations tested. Under normal conditions, the default fate of PINC cells is to migrate to the ONL and, likely, replenish the rod progenitor pool. PINC respond to injury (both surgical and light-dependent) by increasing their mitotic rate; this increase is long lived, but there are no changes in the expression level of Pax6. PINC probably are a heterogenous cell population that can be specified for ultimate, different purposes: creating rod precursors, creating founder cells, creating cone precursors. Several fates are recognized now, but others may also be possible.
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Affiliation(s)
- Maria Paula Faillace
- Department of Physiology School of Medicine, University of California at San Francisco, San Francisco, California 94143, USA
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Abstract
Several studies have indicated that the rainbow trout (Oncorhynchus mykiss) loses ultraviolet (UV) sensitivity and the associated UV-sensitive corner cones when the animal transforms from a small (parr) juvenile to a larger, silver-coloured, smolt. Similar changes supposedly take place when parr juveniles are treated with thyroid hormone (T(4)) or retinoic acid. In contrast to previous investigations, this study shows that parr juveniles lack corner cones throughout the lower half of the ventral retina, suggesting that corner cones cease to be incorporated into the ventral retina some time after hatching. This uneven incorporation of corner cones across the retina, when combined with retinal growth, creates a progressively smaller area of lower retina occupied by corner cones. Because in previous studies, the stimulating illumination was directed primarily at the ventral retina, the reported age-dependent changes in UV or polarization sensitivities can be explained by differences in the area of corner cones that was illuminated, and not necessarily by a loss of corner cones. This study also shows: (1) that the double cones from non-ventral mosaics of parr rainbow trout may change in cross-sectional shape, altering the mosaic formation from a square to a row, (2) the existence of a 'pure' (non-changing) square mosaic in the ventral retina, and (3) a potential method, based on differential staining of cone nuclei, to classify paired cones into double or twin cones.
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Affiliation(s)
- I N Flamarique
- Simon Fraser University, Department of Biological Sciences, 8888 University Drive, BC, V5A 1S6, Burnaby, Canada.
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Carleton KL, Kocher TD. Cone opsin genes of african cichlid fishes: tuning spectral sensitivity by differential gene expression. Mol Biol Evol 2001; 18:1540-50. [PMID: 11470845 DOI: 10.1093/oxfordjournals.molbev.a003940] [Citation(s) in RCA: 208] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Spectral tuning of visual pigments is typically accomplished through changes in opsin amino acid sequence. Within a given opsin class, changes at a few key sites control wavelength specificity. To investigate known differences in the visual pigment spectral sensitivity of the Lake Malawi cichlids, Metriaclima zebra (368, 488, and 533 nm) and Dimidiochromis compressiceps (447, 536, and 569 nm), we sequenced cone opsin genes from these species as well as Labeotropheus fuelleborni and Oreochromis niloticus. These cichlids have five distinct classes of cone opsin genes, including two unique SWS-2 genes. Comparisons of the inferred amino acid sequences from the five cone opsin genes of M. zebra, D. compressiceps, and L. fuelleborni show the sequences to be nearly identical. Therefore, evolution of key opsin sites cannot explain the differences in visual pigment sensitivities. Real-time PCR demonstrates that different cichlid species express different subsets of the available cone opsin genes. Metriaclima zebra and L. fuelleborni express a complement of genes which give them UV-shifted visual pigments, while D. compressiceps expresses a different set to produce a red-shifted visual system. Thus, variations in cichlid spectral sensitivity have arisen through evolution of gene regulation, rather than through changes in opsin amino acid sequence.
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Affiliation(s)
- K L Carleton
- Department of Zoology. Program in Genetics, University of New Hampshire, Durham 03824, USA.
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36
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Deutschlander ME, Greaves DK, Haimberger TJ, Hawryshyn CW. Functional mapping of ultraviolet photosensitivity during metamorphic transitions in a salmonid fish, Oncorhynchus mykiss. J Exp Biol 2001; 204:2401-13. [PMID: 11511655 DOI: 10.1242/jeb.204.14.2401] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Ultraviolet visual sensitivity appears to be reduced and, possibly, lost during smoltification in anadromous populations of salmonid fishes. Similar changes occur in non-anadromous salmonids over a mass range that is associated with smoltification in their anadromous conspecifics. However, in sexually mature adult salmonids, ultraviolet-sensitive cones are present in the dorso-temporal retina, suggesting that ultraviolet sensitivity (i) may be regained with sexual maturity or (ii) might never be completely lost. Both smoltification and the transition to sexual maturity are regulated, in part, by the hormone thyroxine. Thyroxine treatment of juvenile Oncorhynchus mykiss results in precocial developmental changes that mimic smoltification, including a reduction of ultraviolet sensitivity. However, whether loss of ultraviolet sensitivity in O. mykiss or in other species of salmonids is complete during normal development (or in response to thyroxine treatment) is unclear. In the present study, we have ‘mapped’ topographically ultraviolet photosensitivity during natural and hormone-induced smoltification. Thyroxine-treated O. mykiss juveniles and anadromous steelhead O. mykiss smolts were examined for ultraviolet visual sensitivity by recording compound action potentials from the optic nerve. By selectively illuminating either the dorsal or the ventral retina, we have shown that the reduction of ultraviolet sensitivity occurs primarily in the ventral retina in both groups of fish. Ultraviolet sensitivity remains intact in the dorsal retina.
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Affiliation(s)
- M E Deutschlander
- Department of Biology, University of Victoria, PO Box 3020 STN CSC, Victoria, British Columbia, Canada V8W 3N5
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37
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Hawryshyn CW. Ultraviolet polarization vision in fishes: possible mechanisms for coding e-vector. Philos Trans R Soc Lond B Biol Sci 2000; 355:1187-90. [PMID: 11079395 PMCID: PMC1692819 DOI: 10.1098/rstb.2000.0664] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Polarization vision in vertebrates has been marked with significant controversy over recent decades. In the last decade, however, models from two laboratories have indicated that the spatial arrangement of photoreceptors provides the basis for polarization sensitivity Work in my laboratory, in collaboration with I. Novales Flamarique and F. I. Harosi, has shown that polarization sensitivity depends on a well-defined square cone mosaic pattern and that the biophysical properties of the square cone mosaic probably account for polarization vision in the ultraviolet spectrum. The biophysical mechanism appears to be based on the selective reflection of axial-polarized light by the partitioning membrane, formed along the contact zone between the members of the double cones, onto neighbouring ultraviolet-sensitive cones. In this short review, I discuss the historical development of this research problem.
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Affiliation(s)
- C W Hawryshyn
- Department of Biology, University of Victoria, British Columbia, Canada.
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Carleton KL, Hárosi FI, Kocher TD. Visual pigments of African cichlid fishes: evidence for ultraviolet vision from microspectrophotometry and DNA sequences. Vision Res 2000; 40:879-90. [PMID: 10720660 DOI: 10.1016/s0042-6989(99)00238-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have found evidence for ultraviolet visual capabilities in a Lake Malawi cichlid fish, Metriaclima zebra. Microspectrophotometry of single cones revealed a visual pigment with peak sensitivity at 368+/-4 nm. M. zebra also expresses a putative ultraviolet opsin gene whose sequence is closely related to the SWS-1 opsin for other fishes. Several other African cichlids have a functional copy of this UV gene in their genomic DNA, but do not appear to express this gene as adults. These results suggest that ultraviolet vision is important for some cichlid fishes. UV wavelengths should therefore be included in future studies of cichlid vision, behavior and color patterns.
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Affiliation(s)
- K L Carleton
- Department of Zoology, University of New Hampshire, Rudman Hall, 46 College Road, Durham, NH 03824-2617, USA
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Parkyn DC, Hawryshyn CW. Spectral and ultraviolet-polarisation sensitivity in juvenile salmonids: a comparative analysis using electrophysiology. J Exp Biol 2000; 203:1173-91. [PMID: 10708638 DOI: 10.1242/jeb.203.7.1173] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Spectral and polarisation sensitivity were compared among juvenile (parr) rainbow trout (Oncorhynchus mykiss), steelhead (O. mykiss), cutthroat trout (O. clarki clarki), kokanee (O. nerka) and brook char (Salvelinus fontinalis) using multi-unit recording from the optic nerve. Although reared under the same conditions, differences in photopic spectral sensitivity were evident. Specifically, ON-responses were co-dominated by L- and M-cone mechanisms in all fish except O. nerka, consistent with an M-cone mechanism sensitivity. The sensitivity of OFF-responses was dominated by the M-cone mechanism for all fish, but O. mykiss appeared to show an additional contribution from the L-cone mechanism. Using chromatic adaptation, an independent ultraviolet-sensitive mechanism is described for the first time for the salmonid genus Salvelinus. In addition, this ultraviolet-cone mechanism was present in the members of the genus Oncorhynchus that were examined. Thus, ultraviolet sensitivity appears to be common to the major extant clades of the subfamily Salmoninae. All species showed differential sensitivity to both vertical and horizontal linearly polarised light. This sensitivity differed between ON- and OFF-responses. The ON-responses were maximally sensitive to both vertically and horizontally polarised light, whereas the OFF-responses displayed maximal sensitivity to horizontally polarised light in all species, with reduced sensitivity to vertically polarised light compared with ON-responses. Because of the similarity in the physiological characteristics of polarisation sensitivity among the salmonid species examined, no relationship between the degree of migratory tendency and the ability to detect polarised light could be identified.
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Affiliation(s)
- D C Parkyn
- Department of Biology, University of Victoria, PO Box 3020, STN CSC, Victoria, British Columbia, Canada V8W 3N5.
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40
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Novales Flamarique I. The ontogeny of ultraviolet sensitivity, cone disappearance and regeneration in the sockeye salmon Oncorhynchus nerka. J Exp Biol 2000; 203:1161-72. [PMID: 10708637 DOI: 10.1242/jeb.203.7.1161] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study examines the spectral sensitivity and cone topography of the sockeye salmon Oncorhynchus nerka throughout its life history with special emphasis on ultraviolet sensitivity. Electrophysiological recordings from the optic nerve show that ultraviolet sensitivity is greatly diminished at the smolt stage but reappears in adult fish weighing about 201 g. Concomitantly, light microscopy observations of the retina show that ultraviolet cones disappear from the dorsal and temporal retina at the smolt stage but reappear at the adult stage. These changes occur for sockeye salmon raised in fresh water or salt water after smoltification. In contrast to this ultraviolet cycle, the other cone mechanisms (short-, middle- and long-wavelength-sensitive) and the rod mechanism remain present throughout ontogeny. The natural appearance and disappearance of ultraviolet cones in salmonid retinas follows surges in blood thyroxine at critical developmental periods. Their presence coincides with times of prominent feeding on zooplankton and/or small fish that may be more visible under ultraviolet light. It is proposed that the primary function of ultraviolet cones in salmonids is to improve prey contrast.
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Affiliation(s)
- I Novales Flamarique
- Department of Biology, University of Victoria, PO Box 3020, Victoria, British Columbia, Canada V8W 3N5.
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Szél A, Lukáts A, Fekete T, Szepessy Z, Röhlich P. Photoreceptor distribution in the retinas of subprimate mammals. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2000; 17:568-579. [PMID: 10708038 DOI: 10.1364/josaa.17.000568] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Relevant data on the distribution of color cones are summarized, with special emphasis on the marked dorsoventral asymmetries observed in a number of mammalian species. In addition, an overview is given of studies that demonstrate the coexistence of two visual pigments within the same cone cell. The biological significance of these phenomena is discussed in conjunction with comparative immunocytochemical analyses of subprimate retinas. Based on various cone distribution patterns and temporal and spatial visual pigment coexpression, two models of cone photoreceptor differentiation are suggested.
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Affiliation(s)
- A Szél
- Department of Human Morphology, Semmelweis University of Medicine, Budapest, Hungary.
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Shand J, Archer MA, Collin SP. Ontogenetic changes in the retinal photoreceptor mosaic in a fish, the black bream, Acanthopagrus butcheri. J Comp Neurol 1999; 412:203-17. [PMID: 10441751 DOI: 10.1002/(sici)1096-9861(19990920)412:2<203::aid-cne2>3.0.co;2-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The morphological development of the photoreceptor mosaic was followed by light and electron microscopy in a specific region of dorsal retina of the black bream, Acanthopagrus butcheri (Sparidae, Teleostei), from hatching to eight weeks of age. The retina was differentiated when the larvae reached a total length of 3 mm (3-5 days posthatch). Single cones, arranged in tightly packed rows, were the only morphologically distinct type of photoreceptor present until the larvae were 6 mm (day 15) in standard length (SL). At this time, the rod nuclei had become differentiated and the ellipsoids of selected cones began to form subsurface cisternae along neighbouring cone membranes. In this way, double, triple, quadruple, and occasionally photoreceptor chains of up to 10 cones were formed. At 8 mm SL, there was little apparent order in the photoreceptor mosaic. However, concomitant with subsequent growth, quadruple and other multiple cone receptors disappeared, with the exception of the triple cones, which gradually reduced in both number and retinal coverage to be restricted to central retina by 15 mm SL (days 40-55). Following this stage, the arrangement of double and single cones peripheral to the region of triple cones in dorsal retina was transformed into the adult pattern of a regular mosaic of four double cones surrounding a single cone. These results demonstrate that an established photoreceptor mosaic of rows of single cones can be reorganised to form a regular square mosaic composed of single and double cones.
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Affiliation(s)
- J Shand
- Department of Zoology, University of Western Australia, Nedlands, Western Australia 6907, Australia.
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