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Battelle BA. Opsins and Their Expression Patterns in the Xiphosuran Limulus polyphemus. THE BIOLOGICAL BULLETIN 2017; 233:3-20. [PMID: 29182506 DOI: 10.1086/693730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The American horseshoe crab Limulus polyphemus (Linnaeus, 1758) is one of four extant species of xiphosuran chelicerates, the sister group to arachnids. Because of their position in the arthropod family tree and because they exhibit many plesiomorphic characteristics, Xiphosura are considered a proxy for the euchelicerate ancestor and therefore important for understanding the evolution and diversification of chelicerates and arthropods. Limulus polyphemus is the most extensively studied xiphosuran, and its visual system has long been a focus of studies critical for our understanding of basic mechanisms of vision and the evolution of visual systems in arthropods. Building upon a wealth of information about the anatomy and physiology of its visual system, advances in genetic approaches have greatly expanded possibilities for understanding its biochemistry. This review focuses on studies of opsin expression in L. polyphemus, which have been significantly advanced by the availability of transcriptomes and a recent high-quality assembly of its genome. These studies show that the repertoire of expressed opsins in L. polyphemus is far larger than anticipated, that the regulation of their expression in rhabdoms is far more complex than anticipated, and that photosensitivity may be distributed widely throughout the L. polyphemus central nervous system. The visual system of L. polyphemus is now arguably the best understood among chelicerates, and as such, it is a critical resource for furthering our understanding of the evolution and diversification of visual systems in arthropods.
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Key Words
- CNS, central nervous system
- LE, lateral eye
- LWS, long wavelength-sensitive
- LpArthOps, Limulus arthropsin
- LpCOps, Limulus C-type opsin
- LpOps, Limulus opsin
- LpPerOps, Limulus peropsin
- ME, median eye
- MWS, medium wavelength-sensitive
- Rh-LpOps, Limulus opsin in rhabdoms
- SWS, short wavelength-sensitive
- VE, ventral eye
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Battelle BA. Simple Eyes, Extraocular Photoreceptors and Opsins in the American Horseshoe Crab. Integr Comp Biol 2016; 56:809-819. [DOI: 10.1093/icb/icw093] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Battelle BA, Kempler KE, Saraf SR, Marten CE, Dugger DR, Speiser DI, Oakley TH. Opsins in Limulus eyes: characterization of three visible light-sensitive opsins unique to and co-expressed in median eye photoreceptors and a peropsin/RGR that is expressed in all eyes. J Exp Biol 2015; 218:466-79. [PMID: 25524988 PMCID: PMC4317242 DOI: 10.1242/jeb.116087] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
The eyes of the horseshoe crab Limulus polyphemus have long been used for studies of basic mechanisms of vision, and the structure and physiology of Limulus photoreceptors have been examined in detail. Less is known about the opsins Limulus photoreceptors express. We previously characterized a UV opsin (LpUVOps1) that is expressed in all three types of Limulus eyes (lateral compound eyes, median ocelli and larval eyes) and three visible light-sensitive rhabdomeric opsins (LpOps1, -2 and -5) that are expressed in Limulus lateral compound and larval eyes. Physiological studies showed that visible light-sensitive photoreceptors are also present in median ocelli, but the visible light-sensitive opsins they express were unknown. In the current study we characterize three newly identified, visible light-sensitive rhabdomeric opsins (LpOps6, -7 and -8) that are expressed in median ocelli. We show that they are ocellar specific and that all three are co-expressed in photoreceptors distinct from those expressing LpUVOps1. Our current findings show that the pattern of opsin expression in Limulus eyes is much more complex than previously thought and extend our previous observations of opsin co-expression in visible light-sensitive Limulus photoreceptors. We also characterize a Limulus peropsin/RGR (LpPerOps1). We examine the phylogenetic relationship of LpPerOps1 with other peropsins and RGRs, demonstrate that LpPerOps1 transcripts are expressed in each of the three types of Limulus eyes and show that the encoded protein is expressed in membranes of cells closely associated with photoreceptors in each eye type. These finding suggest that peropsin was in the opsin repertoire of euchelicerates.
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Affiliation(s)
- Barbara-Anne Battelle
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Karen E Kempler
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Spencer R Saraf
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Catherine E Marten
- Whitney Laboratory for Marine Bioscience and Departments of Neuroscience and Biology, 9505 Ocean Shore Blvd, University of Florida, St Augustine, FL 32080, USA
| | - Donald R Dugger
- Department of Ophthalmology, University of Florida, Gainesville, FL 32080, USA
| | - Daniel I Speiser
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Todd H Oakley
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA
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Battelle BA, Kempler KE, Harrison A, Dugger DR, Payne R. Opsin expression in Limulus eyes: a UV opsin is expressed in each eye type and co-expressed with a visible light-sensitive opsin in ventral larval eyes. ACTA ACUST UNITED AC 2014; 217:3133-45. [PMID: 24948643 DOI: 10.1242/jeb.107383] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The eyes of the horseshoe crab, Limulus polyphemus, are a model for studies of visual function and the visual systems of euarthropods. Much is known about the structure and function of L. polyphemus photoreceptors, much less about their photopigments. Three visible-light-sensitive L. polyphemus opsins were characterized previously (LpOps1, 2 and 5). Here we characterize a UV opsin (LpUVOps1) that is expressed in all three types of L. polyphemus eyes. It is expressed in most photoreceptors in median ocelli, the only L. polyphemus eyes in which UV sensitivity was previously detected, and in the dendrite of eccentric cells in lateral compound eyes. Therefore, eccentric cells, previously thought to be non-photosensitive second-order neurons, may actually be UV-sensitive photoreceptors. LpUVOps1 is also expressed in small photoreceptors in L. polyphemus ventral larval eyes, and intracellular recordings from these photoreceptors confirm that LpUVOps1 is an active, UV-sensitive photopigment. These photoreceptors also express LpOps5, which we demonstrate is an active, long-wavelength-sensitive photopigment. Thus small photoreceptors in ventral larval eyes, and probably those of the other larval eyes, have dual sensitivity to UV and visible light. Interestingly, the spectral tuning of small ventral photoreceptors may change day to night, because the level of LpOps5 in their rhabdoms is lower during the day than during the night, whereas LpUVOps1 levels show no diurnal change. These and previous findings show that opsin co-expression and the differential regulation of co-expressed opsins in rhabdoms is a common feature of L. polyphemus photoreceptors.
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Affiliation(s)
- Barbara-Anne Battelle
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA Departments of Neuroscience and Biology, University of Florida, Gainesville, FL 32611, USA
| | - Karen E Kempler
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA Departments of Neuroscience and Biology, University of Florida, Gainesville, FL 32611, USA
| | - Alexandra Harrison
- Whitney Laboratory for Marine Bioscience, University of Florida, St Augustine, FL 32080, USA Departments of Neuroscience and Biology, University of Florida, Gainesville, FL 32611, USA
| | - Donald R Dugger
- Department of Ophthalmology, University of Florida, Gainesville, FL 32610, USA
| | - Richard Payne
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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Battelle BA. The eyes of Limulus polyphemus (Xiphosura, Chelicerata) and their afferent and efferent projections. ARTHROPOD STRUCTURE & DEVELOPMENT 2006; 35:261-74. [PMID: 18089075 DOI: 10.1016/j.asd.2006.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Accepted: 06/22/2006] [Indexed: 05/16/2023]
Abstract
The visual system of the American horseshoe crab Limulus polyphemus (L. polyphemus) is an important preparation for studying the photoresponse, the circadian modulation of the photoresponse and visual information processing. Given its unique position in phylogeny the structure of its visual system also informs studies of the relationships among arthropods and the characteristics of eurarthropods. Much has been learned about the organization of the relatively simple L. polyphemus visual system, but much remains to be discovered. This review summarizes current knowledge of the structure of L. polyphemus eyes and the organization of their afferent and efferent projections and points to important unanswered questions.
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Affiliation(s)
- B-A Battelle
- Whitney Laboratory and Department of Neuroscience, University of Florida, 9505 Ocean Shore Blvd., St. Augustine, FL 32080, USA
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Battelle BA, Dabdoub A, Malone MA, Andrews AW, Cacciatore C, Calman BG, Smith WC, Payne R. Immunocytochemical localization of opsin, visual arrestin, myosin III, and calmodulin in Limulus lateral eye retinular cells and ventral photoreceptors. J Comp Neurol 2001; 435:211-25. [PMID: 11391642 DOI: 10.1002/cne.1203] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The photoreceptors of the horseshoe crab Limulus polyphemus are classical preparations for studies of the photoresponse and its modulation by circadian clocks. An extensive literature details their physiology and ultrastructure, but relatively little is known about their biochemical organization largely because of a lack of antibodies specific for Limulus photoreceptor proteins. We developed antibodies directed against Limulus opsin, visual arrestin, and myosin III, and we have used them to examine the distributions of these proteins in the Limulus visual system. We also used a commercial antibody to examine the distribution of calmodulin in Limulus photoreceptors. Fixed frozen sections of lateral eye were examined with conventional fluorescence microscopy; ventral photoreceptors were studied with confocal microscopy. Opsin, visual arrestin, myosin III, and calmodulin are all concentrated at the photosensitive rhabdomeral membrane, which is consistent with their participation in the photoresponse. Opsin and visual arrestin, but not myosin III or calmodulin, are also concentrated in extra-rhabdomeral vesicles thought to contain internalized rhabdomeral membrane. In addition, visual arrestin and myosin III were found widely distributed in the cytosol of photoreceptors, suggesting that they have functions in addition to their roles in phototransduction. Our results both clarify and raise new questions about the functions of opsin, visual arrestin, myosin III, and calmodulin in photoreceptors and set the stage for future studies of the impact of light and clock signals on the structure and function of photoreceptors.
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Affiliation(s)
- B A Battelle
- Whitney Laboratory and Department of Neuroscience, University of Florida, St. Augustine, Florida 32080, USA.
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Abstract
We have previously shown that the mature optic chiasm of a marsupial is divided morphologically into three regions, two lateral regions in which ipsilaterally projecting axons are confined and a central region containing only contralaterally projecting axons. By contrast, in the chiasms of eutherian (placental) mammals studied to date, there is no tripartite configuration. Ipsilaterally and contralaterally projecting axons from each eye are mixed in the caudal nerve and in each hemichiasm and encounter axons from the opposite eye near the midline of the chiasm. Here, we show that, unlike eutherians, marsupials have astrocytic processes in high concentrations in lateral regions of the nerve and rostral chiasm. Early in development, during the period when optic axons are growing through the chiasm, many intrachiasmatic cells are seen with densities five to eight times higher in lateral than in central chiasmatic regions. Such cells continue to be added to all chiasmatic regions; later in development, considerably more are added centrally, as the chiasm increases in volume. In the mature chiasm, cell densities are similar in all regions. By contrast to the marsupial, cell addition in the chiasm of a placental mammal, the ferret, is almost entirely restricted to later developmental stages, after axons have grown through the chiasm, and there are no obvious spatial variations in the distribution of cells during the period examined. During development, similar to the adult marsupial, ipsilaterally projecting axons do not approach the chiasmatic midline but remain confined laterally. We propose that the cells generated early and seen in high densities in the lateral chiasmatic regions of the marsupial may play a role in guiding retinal axons through this region of pathway selection. These data suggest that there is not a common pattern of developmental mechanisms that control the path of axons through the chiasm of different mammals.
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Affiliation(s)
- A M Harman
- Department of Psychology, University of Western Australia, Nedlands, Australia
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Feng JJ, Carson JH, Morgan F, Walz B, Fein A. Three-dimensional organization of endoplasmic reticulum in the ventral photoreceptors of Limulus. J Comp Neurol 1994; 341:172-83. [PMID: 8163722 DOI: 10.1002/cne.903410204] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Living Limulus ventral photoreceptor cells were injected with long chain lipophilic carbocyanine fluorescent dyes to label the endoplasmic reticulum (ER). The purpose of this study was to examine the continuity, dynamic changes, and structure of the ER in the living cell, using laser scanning confocal microscopy and three-dimensional image reconstruction. In this highly polarized neuron, three lines of evidence indicate that the ER is a continuous network extending throughout both lobes of the cell. First, injection of DiO or DiI results in the labeling of ER throughout both lobes of the cell. Second, three-dimensional image reconstruction of the optical sections reveals a dispersed membrane meshwork which may be the structure that serves to interconnect the ER in the two lobes. Third, in cells fixed before dye injection, the pattern of labeling was similar to that in living cells, indicating that vesicle transport was not responsible for the spread of dye throughout the cell. The overall organization of the ER in the photoreceptor cell is relatively stable; however, the fine structure changes over time. This dynamic process appears to represent continual reorganization of the intracellular membranes in the cell. Three morphological types of ER were observed. The ER of the light-sensitive lobe, identified by coinjection of rhodamine-phalloidin to label the microvillar actin, is characterized by a concentration of stratiform membranes interconnected by thin tubular cross-bridges. The perinuclear ER is characterized by a tangle of convoluted tubules sometimes terminating in bulbous structures. Finally, there is a fine tubular reticulum dispersed throughout the cell.
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Affiliation(s)
- J J Feng
- Department of Physiology, University of Connecticut Health Center, Farmington 06032
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Zhang HJ, Jinks RN, Wishart AC, Battelle BA, Chamberlain SC, Fahrenbach WH, Kass L. An enzymatically enhanced recording technique for Limulus ventral photoreceptors: physiology, biochemistry, and morphology. Vis Neurosci 1994; 11:41-52. [PMID: 8011582 DOI: 10.1017/s0952523800011093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Enzymatic treatments that facilitated whole-cell electrophysiological recordings were used on Limulus ventral photoreceptor cells. Ventral optic nerves were treated with either collagenase or collagenase, papain, and trypsin. Either treatment greatly increased the ease of making whole-cell recordings of transmembrane potentials. Light responses obtained from enzyme-treated photoreceptor cells were nearly identical to results obtained without enzyme treatment and compared favorably to in vivo recordings of light responses from the compound lateral eye. Enzyme-treated cells also responded to applied octopamine, as do untreated cells, with an increased phosphorylation of a 122-kD protein. This suggests that the external receptors and internal biochemical machinery required for at least one second-messenger cascade are present after enzyme treatment. The morphological integrity of enzyme-treated photoreceptor cells was examined with light microscopy as well as with scanning and transmission electron microscopy. In general, we found that each enzyme treatment greatly reduced the integrity of the layers of glial cells that surround the photoreceptor cells thereby making these cells easily accessible for whole-cell recordings of transmembrane potentials. The morphology of the rhabdomere was normal after enzymatic degradation of the adjacent glial covering.
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Affiliation(s)
- H J Zhang
- Department of Zoology, University of Maine, Orono 04469
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Harman AM, Sanderson KJ, Beazley LD. Biphasic retinal neurogenesis in the brush-tailed possum, Trichosurus vulpecula: further evidence for the mechanisms involved in formation of ganglion cell density gradients. J Comp Neurol 1992; 325:595-606. [PMID: 1469115 DOI: 10.1002/cne.903250411] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We investigated cell generation in the retina of the brush-tailed possum (Trichosurus vulpecula) by using tritiated (3H)-thymidine labelling of newly generated cells. Animals aged between postnatal day (P) 5 and 85 each received a single injection of 3H-thymidine. Following autoradiographic processing, maps of labelled cells were constructed from retinal sections. Retinal cell generation takes place in two phases, the first is concluding in the retinal periphery at P53 as the second is seen to commence in midtemporal retina. In the first phase, cells in central retina are generated earlier than those in peripheral regions. In the second phase, cells complete their final division in midtemporal retina first and in the periphery last. Cells generated in the first phase comprise virtually all cells in the ganglion cell layer, amacrine cells, horizontal cells, and cones. Ganglion cells are produced at a slightly earlier stage than displaced amacrine cells, horizontal cells, or cones. Amacrine cells in the inner nuclear layer are the final cells produced in the first phase. When ganglion cells and amacrine cells are pooled, their combined rate of production matches that of the other cell types. These data indicate that the ratio of displaced amacrine cells: horizontal cells: cones: combined ganglion cells and amacrine cells does not change throughout development. However, the ratio of ganglion cells:macrines changes steadily as development proceeds to favour amacrine cells. In the second phase, sparse numbers of nonganglion cells in the ganglion cell layer and large numbers of bipolar and Müller cells are produced along with all rods. The two phases in the possum are similar to those seen in the wallaby, the quokka. However, fewer cells are added in central retina in the possum than in the quokka and cell addition continues for a more extended period in the periphery in the possum. We suggest that this difference in cell addition could account for the development of a more pronounced visual streak of retinal ganglion cells in the possum than in the quokka. A comparison of possum retinal cell generation with that of other marsupials adds support for the "homochrony theory."
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Affiliation(s)
- A M Harman
- Department of Psychology, University of Western Australia, Nedlands
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Herman KG. Light-stimulated rhabdom turnover in Limulus ventral photoreceptors maintained in vitro. J Comp Neurol 1991; 303:11-21. [PMID: 2005235 DOI: 10.1002/cne.903030103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of light in turnover of photosensitive membranes was studied in isolated photoreceptors maintained in vitro. Ventral photoreceptors of the horseshoe crab, Limulus polyphemus, were used since they have been the subjects of many in vitro physiological studies. This study shows that the two classes of ventral photoreceptors, the large and small photoreceptors (Herman: companion paper), differ in their morphological response to light. The rhabdom of small photoreceptors is remarkable for its regularity, independent of lighting condition. The photosensitive microvilli of the rhabdom of small photoreceptors are narrow and almost always tightly packed in a hexagonal arrangement. In contrast, the morphology of the rhabdom of the large ventral photoreceptors is different in the dark and in the light, and the rhabdom undergoes turnover during lighting transitions. When fully dark-adapted, the photosensitive microvilli of large photoreceptors are narrow and well organized, sometimes in a crystalline array. However, in the light-adapted state, the microvilli are much thicker and very irregular. The transitions between the dark and light-adapted states, examined at midday, are rapid. After 5 minutes light exposure, the microvilli are dilated at their bases and shed membranes are present in the cytoplasm. By 30 minutes after light onset, the appearance of the rhabdom of large photoreceptors is indistinguishable from fully light-adapted cells. The transition to the dark-adapted state is equally rapid. Even at 5 or 12 minutes after light offset, most microvilli are narrow and quite regular, and by 30 minutes, the rhabdom usually appears to be fully dark-adapted. These experiments show that both the synthetic and degradative phases of rhabdom renewal take place in isolated photoreceptors. No efferent neural activity is required to initiate turnover; rather, changes in illumination alone are sufficient to generate rhabdom turnover in large ventral photoreceptors in vitro.
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Affiliation(s)
- K G Herman
- Laboratory of Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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