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Corredor VH, Hauzman E, Gonçalves ADS, Ventura DF. Genetic characterization of the visual pigments of the red-eared turtle (Trachemys scripta elegans) and computational predictions of the spectral sensitivity. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2022. [DOI: 10.1016/j.jpap.2022.100141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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2
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Eilertsen M, Davies WIL, Patel D, Barnes JE, Karlsen R, Mountford JK, Stenkamp DL, Patel JS, Helvik JV. An EvoDevo Study of Salmonid Visual Opsin Dynamics and Photopigment Spectral Sensitivity. Front Neuroanat 2022; 16:945344. [PMID: 35899127 PMCID: PMC9309310 DOI: 10.3389/fnana.2022.945344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/23/2022] [Indexed: 11/29/2022] Open
Abstract
Salmonids are ideal models as many species follow a distinct developmental program from demersal eggs and a large yolk sac to hatching at an advanced developmental stage. Further, these economically important teleosts inhabit both marine- and freshwaters and experience diverse light environments during their life histories. At a genome level, salmonids have undergone a salmonid-specific fourth whole genome duplication event (Ss4R) compared to other teleosts that are already more genetically diverse compared to many non-teleost vertebrates. Thus, salmonids display phenotypically plastic visual systems that appear to be closely related to their anadromous migration patterns. This is most likely due to a complex interplay between their larger, more gene-rich genomes and broad spectrally enriched habitats; however, the molecular basis and functional consequences for such diversity is not fully understood. This study used advances in genome sequencing to identify the repertoire and genome organization of visual opsin genes (those primarily expressed in retinal photoreceptors) from six different salmonids [Atlantic salmon (Salmo salar), brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tshawytcha), coho salmon (Oncorhynchus kisutch), rainbow trout (Oncorhynchus mykiss), and sockeye salmon (Oncorhynchus nerka)] compared to the northern pike (Esox lucius), a closely related non-salmonid species. Results identified multiple orthologues for all five visual opsin classes, except for presence of a single short-wavelength-sensitive-2 opsin gene. Several visual opsin genes were not retained after the Ss4R duplication event, which is consistent with the concept of salmonid rediploidization. Developmentally, transcriptomic analyzes of Atlantic salmon revealed differential expression within each opsin class, with two of the long-wavelength-sensitive opsins not being expressed before first feeding. Also, early opsin expression in the retina was located centrally, expanding dorsally and ventrally as eye development progressed, with rod opsin being the dominant visual opsin post-hatching. Modeling by spectral tuning analysis and atomistic molecular simulation, predicted the greatest variation in the spectral peak of absorbance to be within the Rh2 class, with a ∼40 nm difference in λ max values between the four medium-wavelength-sensitive photopigments. Overall, it appears that opsin duplication and expression, and their respective spectral tuning profiles, evolved to maximize specialist color vision throughout an anadromous lifecycle, with some visual opsin genes being lost to tailor marine-based vision.
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Affiliation(s)
- Mariann Eilertsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Wayne Iwan Lee Davies
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
- School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Melbourne, VIC, Australia
| | - Dharmeshkumar Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States
| | - Jonathan E. Barnes
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States
| | - Rita Karlsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Jessica Kate Mountford
- School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Melbourne, VIC, Australia
- Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
- Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID, United States
| | - Jagdish Suresh Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States
| | - Jon Vidar Helvik
- Department of Biological Sciences, University of Bergen, Bergen, Norway
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3
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Hickey DG, Davies WIL, Hughes S, Rodgers J, Thavanesan N, MacLaren RE, Hankins MW. Chimeric human opsins as optogenetic light sensitisers. J Exp Biol 2021; 224:270919. [PMID: 34151984 PMCID: PMC8325934 DOI: 10.1242/jeb.240580] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 06/08/2021] [Indexed: 12/03/2022]
Abstract
Human opsin-based photopigments have great potential as light-sensitisers, but their requirement for phototransduction cascade-specific second messenger proteins may restrict their functionality in non-native cell types. In this study, eight chimeric human opsins were generated consisting of a backbone of either a rhodopsin (RHO) or long-wavelength-sensitive (LWS) opsin and intracellular domains from Gq/11-coupled human melanopsin. Rhodopsin/melanopsin chimeric opsins coupled to both Gi and Gq/11 pathways. Greater substitution of the intracellular surface with corresponding melanopsin domains generally showed greater Gq/11 activity with a decrease in Gi activation. Unlike melanopsin, rhodopsin and rhodopsin/melanopsin chimeras were dependent upon exogenous chromophore to function. By contrast, wild-type LWS opsin and LWS opsin/melanopsin chimeras showed only weak Gi activation in response to light, whilst Gq/11 pathway activation was not detected. Immunocytochemistry (ICC) demonstrated that chimeric opsins with more intracellular domains of melanopsin were less likely to be trafficked to the plasma membrane. This study demonstrates the importance of Gα coupling efficiency to the speed of cellular responses and created human opsins with a unique combination of properties to expand the range of customised optogenetic biotools for basic research and translational therapies. Summary: Combining different domains of human visual opsins and melanopsin creates functionally unique chimeric opsins with potential optogenetic applications.
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Affiliation(s)
- Doron G Hickey
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,The Royal Victorian Eye and Ear Hospital, Melbourne, VIC 3002, Australia
| | - Wayne I L Davies
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,Umeå Centre for Molecular Medicine, Umeå University, Umeå, S-90187, Sweden.,School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Melbourne, VIC 3086, Australia
| | - Steven Hughes
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, OX1 3QU, UK
| | - Jessica Rodgers
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, OX1 3QU, UK.,Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, M13 9PT, UK
| | | | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust and Oxford NIHR Biomedical Research Centre, Oxford, OX3 9DU,UK
| | - Mark W Hankins
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, OX1 3QU, UK.,Sleep and Circadian Neuroscience Institute, University of Oxford, Oxford, OX1 3QU, UK
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4
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Liu D, Wang X, Guo H, Zhang X, Zhang M, Tang W. Chromosome-level genome assembly of the endangered humphead wrasse Cheilinus undulatus: Insight into the expansion of opsin genes in fishes. Mol Ecol Resour 2021; 21:2388-2406. [PMID: 34003602 DOI: 10.1111/1755-0998.13429] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 04/30/2021] [Accepted: 05/10/2021] [Indexed: 11/26/2022]
Abstract
Wrasses are dominant components of major coral reef systems. Among wrasses, Cheilinus undulatus is an endangered species with high economic and ecological value that exhibits sex reversal of females to males, while sexual selection occurs in breeding aggregations. However, the molecular-associated mechanism underlying this remains unclear. Opsin gene diversification is regarded as a potent force in sexual selection. Here we present a genome assembly of C. undulatus, using Illumina, Nanopore and Hi-C sequencing. The 1.17 Gb genome was generated from 328 contigs with an N50 length of 16.5 Mb and anchored to 24 chromosomes. In total, 22,218 genes were functionally annotated, and 96.36% of BUSCO genes were fully represented. Transcriptomic analyses showed that 96.79% of the predicted genes were expressed. Transposons were most abundant, accounting for 39.88% of the genome, with low divergence, owing to their evolution with close species ~60.53 million years ago. In total, 567/1,826 gene families were expanded and contracted in the reconstructed phylogeny, respectively. Forty-six genes were under positive selection. Comparative genomic analyses with other fish revealed expansion of opsin SWS2B, LWS1 and Rh2. The elevated duplicates of SWS2B were generated by gene conversions via transposition of transposons followed by nonallelic homologous recombination. Amino acid substitutions of opsin paralogues occurred at key tuning sites, causing a spectral shift in maximal absorbance of visual pigment to capture functional changes. Among these opsin genes, SWS2B-3 and 4 and Rh1 are expressed in the retina. The genome sequence of C. undulatus provides valuable resources for future investigation of the conservation, evolution and behaviour of fishes.
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Affiliation(s)
- Dong Liu
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai, China.,National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Xinyang Wang
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai, China.,National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Hongyi Guo
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai, China.,National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Xuguang Zhang
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai, China.,National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Ming Zhang
- Department of Epidemiology and Biostatistics, University of Georgia, Athens, GA, USA
| | - Wenqiao Tang
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Shanghai Ocean University, Shanghai, China.,National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
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Schluessel V, Rick IP, Seifert FD, Baumann C, Lee Davies WI. Not just shades of grey: life is full of colour for the ocellate river stingray (Potamotrygon motoro). J Exp Biol 2021; 224:237826. [PMID: 33771913 DOI: 10.1242/jeb.226142] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 03/19/2021] [Indexed: 12/14/2022]
Abstract
Previous studies have shown that marine stingrays have the anatomical and physiological basis for colour vision, with cone spectral sensitivity in the blue to green range of the visible spectrum. Behavioural studies on Glaucostegus typus also showed that blue and grey can be perceived and discriminated. The present study is the first to assess visual opsin genetics in the ocellate river stingray (Potamotrygon motoro) and test whether individuals perceive colour in two alternative forced choice experiments. Retinal transcriptome profiling using RNA-Seq and quantification demonstrated the presence of lws and rh2 cone opsin genes and a highly expressed single rod (rh1) opsin gene. Spectral tuning analysis predicted these vitamin A1-based visual photopigments to exhibit spectral absorbance maxima at 461 nm (rh2), 496 nm (rh1) and 555 nm (lws); suggesting the presence of dichromacy in this species. Indeed, P. motoro demonstrates the potential to be equally sensitive to wavelengths from 380 to 600 nm of the visible spectrum. Behavioural results showed that red and green plates, as well as blue and yellow plates, were readily discriminated based on colour; however, brightness differences also played a part in the discrimination of blue and yellow. Red hues of different brightness were distinguished significantly above chance level from one another. In conclusion, the genetic and behavioural results support prior data on marine stingrays. However, this study suggests that freshwater stingrays of the family Potamotrygonidae may have a visual colour system that has ecologically adapted to a riverine habitat.
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Affiliation(s)
- Vera Schluessel
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
| | - Ingolf P Rick
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
| | - Friederike Donata Seifert
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
| | - Christina Baumann
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany
| | - Wayne Iwan Lee Davies
- Institute of Zoology, Rheinische Friedrich-Wilhelms-Universität Bonn, Poppelsdorfer Schloss, Meckenheimer Allee 169, 53115 Bonn, Germany.,Umeå Centre for Molecular Medicine (UCMM), Umeå University, 901 87 Umeå, Sweden.,School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Melbourne Campus, Melbourne, VIC 3086, Australia
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6
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Warrington RE, Davies WIL, Hemmi JM, Hart NS, Potter IC, Collin SP, Hunt DM. Visual opsin expression and morphological characterization of retinal photoreceptors in the pouched lamprey (Geotria australis, Gray). J Comp Neurol 2020; 529:2265-2282. [PMID: 33336375 DOI: 10.1002/cne.25092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 11/09/2022]
Abstract
Lampreys are extant members of the agnathan (jawless) vertebrates that diverged ~500 million years ago, during a critical stage of vertebrate evolution when image-forming eyes first emerged. Among lamprey species assessed thus far, the retina of the southern hemisphere pouched lamprey, Geotria australis, is unique, in that it possesses morphologically distinct photoreceptors and expresses five visual photopigments. This study focused on determining the number of different photoreceptors present in the retina of G. australis and whether each cell type expresses a single opsin class. Five photoreceptor subtypes were identified based on ultrastructure and differential expression of one of each of the five different visual opsin classes (lws, sws1, sws2, rh1, and rh2) known to be expressed in the retina. This suggests, therefore, that the retina of G. australis possesses five spectrally and morphologically distinct photoreceptors, with the potential for complex color vision. Each photoreceptor subtype was shown to have a specific spatial distribution in the retina, which is potentially associated with changes in spectral radiance across different lines of sight. These results suggest that there have been strong selection pressures for G. australis to maintain broad spectral sensitivity for the brightly lit surface waters that this species inhabits during its marine phase. These findings provide important insights into the functional anatomy of the early vertebrate retina and the selection pressures that may have led to the evolution of complex color vision.
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Affiliation(s)
- Rachael E Warrington
- Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, California, USA.,School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Wayne I L Davies
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia.,Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden.,Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia.,School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Nathan S Hart
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia.,Department of Biological Sciences, Macquarie University, North Ryde, New South Wales, Australia
| | - Ian C Potter
- Centre for Sustainable Aquatic Ecosystems, Murdoch University, Perth, Western Australia, Australia
| | - Shaun P Collin
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia.,School of Life Sciences, La Trobe University, Melbourne, Victoria, Australia
| | - David M Hunt
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia.,Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
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7
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Hart NS, Lamb TD, Patel HR, Chuah A, Natoli RC, Hudson NJ, Cutmore SC, Davies WIL, Collin SP, Hunt DM. Visual Opsin Diversity in Sharks and Rays. Mol Biol Evol 2020; 37:811-827. [PMID: 31770430 DOI: 10.1093/molbev/msz269] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The diversity of color vision systems found in extant vertebrates suggests that different evolutionary selection pressures have driven specializations in photoreceptor complement and visual pigment spectral tuning appropriate for an animal's behavior, habitat, and life history. Aquatic vertebrates in particular show high variability in chromatic vision and have become important models for understanding the role of color vision in prey detection, predator avoidance, and social interactions. In this study, we examined the capacity for chromatic vision in elasmobranch fishes, a group that have received relatively little attention to date. We used microspectrophotometry to measure the spectral absorbance of the visual pigments in the outer segments of individual photoreceptors from several ray and shark species, and we sequenced the opsin mRNAs obtained from the retinas of the same species, as well as from additional elasmobranch species. We reveal the phylogenetically widespread occurrence of dichromatic color vision in rays based on two cone opsins, RH2 and LWS. We also confirm that all shark species studied to date appear to be cone monochromats but report that in different species the single cone opsin may be of either the LWS or the RH2 class. From this, we infer that cone monochromacy in sharks has evolved independently on multiple occasions. Together with earlier discoveries in secondarily aquatic marine mammals, this suggests that cone-based color vision may be of little use for large marine predators, such as sharks, pinnipeds, and cetaceans.
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Affiliation(s)
- Nathan S Hart
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Hardip R Patel
- Department of Genome Sciences, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Aaron Chuah
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Riccardo C Natoli
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,ANU Medical School, The Australian National University, Canberra, ACT, Australia
| | - Nicholas J Hudson
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Scott C Cutmore
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Wayne I L Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Bundoora, VIC, Australia
| | - David M Hunt
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia.,Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Crawley, WA, Australia
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8
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Patel D, Barnes JE, Davies WIL, Stenkamp DL, Patel JS. Short-wavelength-sensitive 2 (Sws2) visual photopigment models combined with atomistic molecular simulations to predict spectral peaks of absorbance. PLoS Comput Biol 2020; 16:e1008212. [PMID: 33085657 PMCID: PMC7605715 DOI: 10.1371/journal.pcbi.1008212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/02/2020] [Accepted: 09/21/2020] [Indexed: 12/02/2022] Open
Abstract
For many species, vision is one of the most important sensory modalities for mediating essential tasks that include navigation, predation and foraging, predator avoidance, and numerous social behaviors. The vertebrate visual process begins when photons of the light interact with rod and cone photoreceptors that are present in the neural retina. Vertebrate visual photopigments are housed within these photoreceptor cells and are sensitive to a wide range of wavelengths that peak within the light spectrum, the latter of which is a function of the type of chromophore used and how it interacts with specific amino acid residues found within the opsin protein sequence. Minor differences in the amino acid sequences of the opsins are known to lead to large differences in the spectral peak of absorbance (i.e. the λmax value). In our prior studies, we developed a new approach that combined homology modeling and molecular dynamics simulations to gather structural information associated with chromophore conformation, then used it to generate statistical models for the accurate prediction of λmax values for photopigments derived from Rh1 and Rh2 amino acid sequences. In the present study, we test our novel approach to predict the λmax of phylogenetically distant Sws2 cone opsins. To build a model that can predict the λmax using our approach presented in our prior studies, we selected a spectrally-diverse set of 11 teleost Sws2 photopigments for which both amino acid sequence information and experimentally measured λmax values are known. The final first-order regression model, consisting of three terms associated with chromophore conformation, was sufficient to predict the λmax of Sws2 photopigments with high accuracy. This study further highlights the breadth of our approach in reliably predicting λmax values of Sws2 cone photopigments, evolutionary-more distant from template bovine RH1, and provided mechanistic insights into the role of known spectral tuning sites.
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Affiliation(s)
- Dharmeshkumar Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States of America
| | - Jonathan E. Barnes
- Department of Physics, University of Idaho, Moscow, ID, United States of America
| | - Wayne I. L. Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
- The Oceans Graduate School, University of Western Australia, Perth, WA, Australia
- The Oceans Institute, University of Western Australia, Perth, WA, Australia
- Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States of America
- Institute for Bioinformatics and Evolutionary Biology, University of Idaho, Moscow, ID, United States of America
| | - Jagdish Suresh Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States of America
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States of America
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9
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Escobar-Camacho D, Carleton KL, Narain DW, Pierotti MER. Visual pigment evolution in Characiformes: The dynamic interplay of teleost whole-genome duplication, surviving opsins and spectral tuning. Mol Ecol 2020; 29:2234-2253. [PMID: 32421918 DOI: 10.1111/mec.15474] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 05/09/2020] [Accepted: 05/11/2020] [Indexed: 01/06/2023]
Abstract
Vision represents an excellent model for studying adaptation, given the genotype-to-phenotype map that has been characterized in a number of taxa. Fish possess a diverse range of visual sensitivities and adaptations to underwater light, making them an excellent group to study visual system evolution. In particular, some speciose but understudied lineages can provide a unique opportunity to better understand aspects of visual system evolution such as opsin gene duplication and neofunctionalization. In this study, we showcase the visual system evolution of neotropical Characiformes and the spectral tuning mechanisms they exhibit to modulate their visual sensitivities. Such mechanisms include gene duplications and losses, gene conversion, opsin amino acid sequence and expression variation, and A1 /A2 -chromophore shifts. The Characiforms we studied utilize three cone opsin classes (SWS2, RH2, LWS) and a rod opsin (RH1). However, the characiform's entire opsin gene repertoire is a product of dynamic evolution by opsin gene loss (SWS1, RH2) and duplication (LWS, RH1). The LWS- and RH1-duplicates originated from a teleost specific whole-genome duplication as well as characiform-specific duplication events. Both LWS-opsins exhibit gene conversion and, through substitutions in key tuning sites, one of the LWS-paralogues has acquired spectral sensitivity to green light. These sequence changes suggest reversion and parallel evolution of key tuning sites. Furthermore, characiforms' colour vision is based on the expression of both LWS-paralogues and SWS2. Finally, we found interspecific and intraspecific variation in A1 /A2 -chromophores proportions, correlating with the light environment. These multiple mechanisms may be a result of the diverse visual environments where Characiformes have evolved.
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Affiliation(s)
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Devika W Narain
- Environmental Sciences, Anton de Kom University of Suriname, Paramaribo, Suriname
| | - Michele E R Pierotti
- Naos Marine Laboratories, Smithsonian Tropical Research Institute, Panama, Republic of Panama
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10
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Carleton KL, Escobar-Camacho D, Stieb SM, Cortesi F, Marshall NJ. Seeing the rainbow: mechanisms underlying spectral sensitivity in teleost fishes. J Exp Biol 2020; 223:jeb193334. [PMID: 32327561 PMCID: PMC7188444 DOI: 10.1242/jeb.193334] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among vertebrates, teleost eye diversity exceeds that found in all other groups. Their spectral sensitivities range from ultraviolet to red, and the number of visual pigments varies from 1 to over 40. This variation is correlated with the different ecologies and life histories of fish species, including their variable aquatic habitats: murky lakes, clear oceans, deep seas and turbulent rivers. These ecotopes often change with the season, but fish may also migrate between ecotopes diurnally, seasonally or ontogenetically. To survive in these variable light habitats, fish visual systems have evolved a suite of mechanisms that modulate spectral sensitivities on a range of timescales. These mechanisms include: (1) optical media that filter light, (2) variations in photoreceptor type and size to vary absorbance and sensitivity, and (3) changes in photoreceptor visual pigments to optimize peak sensitivity. The visual pigment changes can result from changes in chromophore or changes to the opsin. Opsin variation results from changes in opsin sequence, opsin expression or co-expression, and opsin gene duplications and losses. Here, we review visual diversity in a number of teleost groups where the structural and molecular mechanisms underlying their spectral sensitivities have been relatively well determined. Although we document considerable variability, this alone does not imply functional difference per se. We therefore highlight the need for more studies that examine species with known sensitivity differences, emphasizing behavioral experiments to test whether such differences actually matter in the execution of visual tasks that are relevant to the fish.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | | | - Sara M Stieb
- Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - N Justin Marshall
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
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11
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Govardovskii V, Rotov A, Astakhova L, Nikolaeva D, Firsov M. Visual cells and visual pigments of the river lamprey revisited. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:71-84. [PMID: 31942647 DOI: 10.1007/s00359-019-01395-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 12/04/2019] [Accepted: 12/07/2019] [Indexed: 11/28/2022]
Abstract
Retinas of the river lamprey Lampetra fluviatilis were studied by microspectrophotometry, electroretinography and single-photoreceptor electrophysiology to reconcile the apparently contradictory conclusions on the nature of lamprey photoreceptor cells drawn in the early work by Govardovskii and Lychakov (J Comp Physiology A 154:279-286, 1984) and in recent studies. In agreement with recent works, we confirmed former identification of short photoreceptors as rods and of long photoreceptors as cones. In line with the results of 1984, we show that within a certain range of light intensities the lamprey retina exhibits "color discrimination". We found that the overlap of working intensity ranges of rods and cones is not a unique feature of lamprey short receptors, and suggest that rod-cone (possibly color) vision may be common among vertebrates. We show that the decay of meta-intermediates in lamprey cones occurs almost 100 times faster than in typical rod metarhodopsins. Rate of decay of metarhodopsins of lamprey rods take an intermediate position between typical rods and cones. This makes lamprey rhodopsin similar to transmuted cone visual pigment in "rods" of nocturnal geckos. We argue that defining various types of photoreceptors as simply "rods" and "cones" may be functionally correct, but neglects their genetic, biochemical and morphological features and evolutionary history.
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Affiliation(s)
- Victor Govardovskii
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223, St. Petersburg, Russia.
| | - Alexander Rotov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223, St. Petersburg, Russia
| | - Luba Astakhova
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223, St. Petersburg, Russia
| | - Darya Nikolaeva
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223, St. Petersburg, Russia
| | - Michael Firsov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223, St. Petersburg, Russia
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12
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Musilova Z, Cortesi F, Matschiner M, Davies WIL, Patel JS, Stieb SM, de Busserolles F, Malmstrøm M, Tørresen OK, Brown CJ, Mountford JK, Hanel R, Stenkamp DL, Jakobsen KS, Carleton KL, Jentoft S, Marshall J, Salzburger W. Vision using multiple distinct rod opsins in deep-sea fishes. Science 2019; 364:588-592. [PMID: 31073066 DOI: 10.1126/science.aav4632] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 04/16/2019] [Indexed: 02/01/2023]
Abstract
Vertebrate vision is accomplished through light-sensitive photopigments consisting of an opsin protein bound to a chromophore. In dim light, vertebrates generally rely on a single rod opsin [rhodopsin 1 (RH1)] for obtaining visual information. By inspecting 101 fish genomes, we found that three deep-sea teleost lineages have independently expanded their RH1 gene repertoires. Among these, the silver spinyfin (Diretmus argenteus) stands out as having the highest number of visual opsins in vertebrates (two cone opsins and 38 rod opsins). Spinyfins express up to 14 RH1s (including the most blueshifted rod photopigments known), which cover the range of the residual daylight as well as the bioluminescence spectrum present in the deep sea. Our findings present molecular and functional evidence for the recurrent evolution of multiple rod opsin-based vision in vertebrates.
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Affiliation(s)
- Zuzana Musilova
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland. .,Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Fabio Cortesi
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland. .,Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Michael Matschiner
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway.,Department of Palaeontology and Museum, University of Zurich, Zurich, Switzerland
| | - Wayne I L Davies
- UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia.,School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, The University of Western Australia, Perth, WA, Australia.,Oceans Graduate School, The University of Western Australia, Perth, WA, Australia
| | - Jagdish Suresh Patel
- Center for Modeling Complex Interactions, University of Idaho, Moscow, ID, USA.,Department of Biological Sciences, University of Idaho, Moscow, ID, USA
| | - Sara M Stieb
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland.,Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.,Center for Ecology, Evolution and Biogeochemistry, Department of Fish Ecology and Evolution, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Kastanienbaum, Switzerland
| | - Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.,Red Sea Research Center (RSRC), Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Martin Malmstrøm
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland.,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Ole K Tørresen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Celeste J Brown
- Department of Biological Sciences, University of Idaho, Moscow, ID, USA
| | - Jessica K Mountford
- UWA Oceans Institute, The University of Western Australia, Perth, WA, Australia.,School of Biological Sciences, The University of Western Australia, Perth, WA, Australia.,Lions Eye Institute, The University of Western Australia, Perth, WA, Australia
| | - Reinhold Hanel
- Thünen Institute of Fisheries Ecology, Bremerhaven, Germany
| | | | - Kjetill S Jakobsen
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Sissel Jentoft
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Walter Salzburger
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland. .,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
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13
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Katti C, Stacey-Solis M, Coronel-Rojas NA, Davies WIL. The Diversity and Adaptive Evolution of Visual Photopigments in Reptiles. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00352] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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14
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Abstract
Although much is known about the visual system of vertebrates in general, studies regarding vision in reptiles, and snakes in particular, are scarce. Reptiles display diverse ocular structures, including different types of retinae such as pure cone, mostly rod, or duplex retinas (containing both rods and cones); however, the same five opsin-based photopigments are found in many of these animals. It is thought that ancestral snakes were nocturnal and/or fossorial, and, as such, they have lost two pigments, but retained three visual opsin classes. These are the RH1 gene (rod opsin or rhodopsin-like-1) expressed in rods and two cone opsins, namely LWS (long-wavelength-sensitive) and SWS1 (short-wavelength-sensitive-1) genes. Until recently, the study of snake photopigments has been largely ignored. However, its importance has become clear within the past few years as studies reconsider Walls’ transmutation theory, which was first proposed in the 1930s. In this study, the visual pigments of Bothrops atrox (the common lancehead), a South American pit viper, were examined. Specifically, full-length RH1 and LWS opsin gene sequences were cloned, as well as most of the SWS1 opsin gene. These sequences were subsequently used for phylogenetic analysis and to predict the wavelength of maximum absorbance (λmax) for each photopigment. This is the first report to support the potential for rudimentary color vision in a South American viper, specifically a species that is regarded as being nocturnal.
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15
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Tseng WH, Lin JW, Lou CH, Lee KH, Wu LS, Wang TY, Wang FY, Irschick DJ, Lin SM. Opsin gene expression regulated by testosterone level in a sexually dimorphic lizard. Sci Rep 2018; 8:16055. [PMID: 30375514 PMCID: PMC6207759 DOI: 10.1038/s41598-018-34284-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 10/15/2018] [Indexed: 11/09/2022] Open
Abstract
Expression of nuptial color is usually energetically costly, and is therefore regarded as an 'honest signal' to reflect mate quality. In order to choose a mate with high quality, both sexes may benefit from the ability to precisely evaluate their mates through optimizing visual systems which is in turn partially regulated by opsin gene modification. However, how terrestrial vertebrates regulate their color vision sensitivity is poorly studied. The green-spotted grass lizard Takydromus viridipunctatus is a sexually dimorphic lizard in which males exhibit prominent green lateral colors in the breeding season. In order to clarify relationships among male coloration, female preference, and chromatic visual sensitivity, we conducted testosterone manipulation with mate choice experiments, and evaluated the change of opsin gene expression from different testosterone treatments and different seasons. The results indicated that males with testosterone supplementation showed a significant increase in nuptial color coverage, and were preferred by females in mate choice experiments. By using quantitative PCR (qPCR), we also found that higher levels of testosterone may lead to an increase in rhodopsin-like 2 (rh2) and a decrease in long-wavelength sensitive (lws) gene expression in males, a pattern which was also observed in wild males undergoing maturation as they approached the breeding season. In contrast, females showed the opposite pattern, with increased lws and decreased rh2 expression in the breeding season. We suggest this alteration may facilitate the ability of male lizards to more effectively evaluate color cues, and also may provide females with the ability to more effectively evaluate the brightness of potential mates. Our findings suggest that both sexes of this chromatically dimorphic lizard regulate their opsin expression seasonally, which might play an important role in the evolution of nuptial coloration.
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Affiliation(s)
- Wen-Hsuan Tseng
- Department of Life Science, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Jhan-Wei Lin
- Department of Life Science, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Chen-Han Lou
- Department of Life Science, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Ko-Huan Lee
- Department of Life Science, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Leang-Shin Wu
- Department of Animal Science and Technology, National Taiwan University, Taipei, 106, Taiwan
| | - Tzi-Yuan Wang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Feng-Yu Wang
- National Applied Research Laboratories, Taiwan Ocean Research Institute, Kaohsiung, 801, Taiwan.
| | - Duncan J Irschick
- Department of Biology, 221 Morrill Science Center, University of Massachusetts, Amherst, MA, 01003, USA
| | - Si-Min Lin
- Department of Life Science, National Taiwan Normal University, Taipei, 116, Taiwan.
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16
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Castiglione GM, Chang BS. Functional trade-offs and environmental variation shaped ancient trajectories in the evolution of dim-light vision. eLife 2018; 7:35957. [PMID: 30362942 PMCID: PMC6203435 DOI: 10.7554/elife.35957] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 09/09/2018] [Indexed: 12/11/2022] Open
Abstract
Trade-offs between protein stability and activity can restrict access to evolutionary trajectories, but widespread epistasis may facilitate indirect routes to adaptation. This may be enhanced by natural environmental variation, but in multicellular organisms this process is poorly understood. We investigated a paradoxical trajectory taken during the evolution of tetrapod dim-light vision, where in the rod visual pigment rhodopsin, E122 was fixed 350 million years ago, a residue associated with increased active-state (MII) stability but greatly diminished rod photosensitivity. Here, we demonstrate that high MII stability could have likely evolved without E122, but instead, selection appears to have entrenched E122 in tetrapods via epistatic interactions with nearby coevolving sites. In fishes by contrast, selection may have exploited these epistatic effects to explore alternative trajectories, but via indirect routes with low MII stability. Our results suggest that within tetrapods, E122 and high MII stability cannot be sacrificed-not even for improvements to rod photosensitivity.
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Affiliation(s)
- Gianni M Castiglione
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada
| | - Belinda Sw Chang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Canada
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17
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Lamb TD, Hunt DM. Evolution of the calcium feedback steps of vertebrate phototransduction. Open Biol 2018; 8:180119. [PMID: 30257895 PMCID: PMC6170504 DOI: 10.1098/rsob.180119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 08/29/2018] [Indexed: 01/11/2023] Open
Abstract
We examined the genes encoding the proteins that mediate the Ca-feedback regulatory system in vertebrate rod and cone phototransduction. These proteins comprise four families: recoverin/visinin, the guanylyl cyclase activating proteins (GCAPs), the guanylyl cyclases (GCs) and the sodium/calcium-potassium exchangers (NCKXs). We identified a paralogon containing at least 36 phototransduction genes from at least fourteen families, including all four of the families involved in the Ca-feedback loop (recoverin/visinin, GCAPs, GCs and NCKXs). By combining analyses of gene synteny with analyses of the molecular phylogeny for each of these four families of genes for Ca-feedback regulation, we have established the likely pattern of gene duplications and losses underlying the expansion of isoforms, both before and during the two rounds of whole-genome duplication (2R WGD) that occurred in early vertebrate evolution. Furthermore, by combining our results with earlier evidence on the timing of duplication of the visual G-protein receptor kinase genes, we propose that specialization of proto-vertebrate photoreceptor cells for operation at high and low light intensities preceded the emergence of rhodopsin, which occurred during 2R WGD.
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Affiliation(s)
- Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Australian Capital Territory 2600, Australia
| | - David M Hunt
- Centre for Ophthalmology and Visual Science, The Lions Eye Institute, The University of Western Australia, Western Australia 6009, Australia
- School of Biological Sciences, The University of Western Australia, Western Australia 6009, Australia
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18
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de Busserolles F, Cortesi F, Helvik JV, Davies WIL, Templin RM, Sullivan RKP, Michell CT, Mountford JK, Collin SP, Irigoien X, Kaartvedt S, Marshall J. Pushing the limits of photoreception in twilight conditions: The rod-like cone retina of the deep-sea pearlsides. SCIENCE ADVANCES 2017; 3:eaao4709. [PMID: 29134201 PMCID: PMC5677336 DOI: 10.1126/sciadv.aao4709] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 10/17/2017] [Indexed: 06/07/2023]
Abstract
Most vertebrates have a duplex retina comprising two photoreceptor types, rods for dim-light (scotopic) vision and cones for bright-light (photopic) and color vision. However, deep-sea fishes are only active in dim-light conditions; hence, most species have lost their cones in favor of a simplex retina composed exclusively of rods. Although the pearlsides, Maurolicus spp., have such a pure rod retina, their behavior is at odds with this simplex visual system. Contrary to other deep-sea fishes, pearlsides are mostly active during dusk and dawn close to the surface, where light levels are intermediate (twilight or mesopic) and require the use of both rod and cone photoreceptors. This study elucidates this paradox by demonstrating that the pearlside retina does not have rod photoreceptors only; instead, it is composed almost exclusively of transmuted cone photoreceptors. These transmuted cells combine the morphological characteristics of a rod photoreceptor with a cone opsin and a cone phototransduction cascade to form a unique photoreceptor type, a rod-like cone, specifically tuned to the light conditions of the pearlsides' habitat (blue-shifted light at mesopic intensities). Combining properties of both rods and cones into a single cell type, instead of using two photoreceptor types that do not function at their full potential under mesopic conditions, is likely to be the most efficient and economical solution to optimize visual performance. These results challenge the standing paradigm of the function and evolution of the vertebrate duplex retina and emphasize the need for a more comprehensive evaluation of visual systems in general.
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Affiliation(s)
- Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jon Vidar Helvik
- Department of Biology, University of Bergen, Bergen 5020, Norway
| | - Wayne I. L. Davies
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Rachel M. Templin
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Robert K. P. Sullivan
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Craig T. Michell
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Department of Environmental and Biological Sciences, University of Eastern Finland, Yliopistokatu 7, FI-80101 Joensuu, Finland
| | - Jessica K. Mountford
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Shaun P. Collin
- The Oceans Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
- School of Biological Science, The University of Western Australia, Crawley, Western Australia 6009, Australia
- Lions Eye Institute, The University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Xabier Irigoien
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Marine Research, AZTI - Tecnalia, Herrera Kaia, Portualdea z/g, 20110 Pasaia (Gipuzkoa), Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Stein Kaartvedt
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
- Department of Biosciences, University of Oslo, Oslo 0316, Norway
| | - Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia
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19
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Carvalho LS, Pessoa DMA, Mountford JK, Davies WIL, Hunt DM. The Genetic and Evolutionary Drives behind Primate Color Vision. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00034] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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20
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Lamb TD, Hunt DM. Evolution of the vertebrate phototransduction cascade activation steps. Dev Biol 2017; 431:77-92. [PMID: 28347645 DOI: 10.1016/j.ydbio.2017.03.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/28/2017] [Accepted: 03/20/2017] [Indexed: 02/06/2023]
Abstract
We examine the molecular phylogeny of the proteins underlying the activation steps of vertebrate phototransduction, for both agnathan and jawed vertebrate taxa. We expand the number of taxa analysed and we update the alignment and tree building methodology from a previous analysis. For each of the four primary components (the G-protein transducin alpha subunit, GαT, the cyclic GMP phosphodiesterase, PDE6, and the alpha and beta subunits of the cGMP-gated ion channel, CNGC), the phylogenies appear consistent with expansion from an ancestral proto-vertebrate cascade during two rounds of whole-genome duplication followed by divergence of the agnathan and jawed vertebrate lineages. In each case, we consider possible scenarios for the underlying gene duplications and losses, and we apply relevant constraints to the tree construction. From tests of the topology of the resulting trees, we obtain a scenario for the expansion of each component during 2R that accurately fits the observations. Similar analysis of the visual opsins indicates that the only expansion to have occurred during 2R was the formation of Rh1 and Rh2. Finally, we propose a hypothetical scenario for the conversion of an ancestral chordate cascade into the proto-vertebrate phototransduction cascade, prior to whole-genome duplication. Together, our models provide a plausible account for the origin and expansion of the vertebrate phototransduction cascade.
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Affiliation(s)
- Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, ACT 2600, Australia.
| | - David M Hunt
- The Lions Eye Institute, The University of Western Australia, WA 6009, Australia; School of Biological Sciences, The University of Western Australia, WA 6009, Australia
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21
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Chen L, Wu F, Yuan S, Feng B. Identification and characteristic of three members of the C1q/TNF-related proteins (CTRPs) superfamily in Eudontomyzon morii. FISH & SHELLFISH IMMUNOLOGY 2016; 59:233-240. [PMID: 27771341 DOI: 10.1016/j.fsi.2016.10.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
C1q is the target recognition protein of the classical complement pathway and a major connecting link between innate and acquired immunity. C1q and the multifunctional tumor necrosis factor (TNF) ligand family is of similar crystal structures, are designated the C1q/TNF-related proteins (CTRPs) superfamily. They are involved in processes as diverse as host defense, inflammation, apoptosis, autoimmunity, cell differentiation, organogenesis, hibernation and insulinresistant obesity. In this study, three members of the CTRPs superfamily were isolated and characterized in Yalu River lampreys (Eudontomyzon morii), and are respectively named LaC1qC, LaCTRP1, LaCTRP9. The full-length cDNAs of C1qC-like (LaC1qAL), CTRP1-like (LaCTRP1), and CTRP9-like (LaCTRP9) consist of 723, 762 and 825 bp of nucleotide sequence encoding polypeptides of 241, 254 and 275 amino acids, respectively. All-three proteins share three common domains: a signal peptide at the N terminus, a collagenous domain (characteristic Gly-X-Y repeats), and a C-terminal globular domain. In addition, the higher expression level of the three proteins in heart by RT-PCR and real-time PCR tissue profiling implied that they might involve in immune response or injury repair of the heart in lamprey.
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Affiliation(s)
- Liyong Chen
- Guangdong Province Key Laboratory for Medical Molecular Diagnostics, China-America Cancer Research Institute, Dongguan Scientific Research Center, Guangdong Medical University, Dongguan 523808, China.
| | - Fenfang Wu
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Department of Biochemistry, School of Life Sciences, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275, China
| | - Shengjian Yuan
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Department of Biochemistry, School of Life Sciences, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275, China
| | - Bo Feng
- State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Department of Biochemistry, School of Life Sciences, Sun Yat-Sen (Zhongshan) University, Guangzhou 510275, China
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22
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Lamb TD, Patel H, Chuah A, Natoli RC, Davies WIL, Hart NS, Collin SP, Hunt DM. Evolution of Vertebrate Phototransduction: Cascade Activation. Mol Biol Evol 2016; 33:2064-87. [PMID: 27189541 PMCID: PMC4948711 DOI: 10.1093/molbev/msw095] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We applied high-throughput sequencing to eye tissue from several species of basal vertebrates (a hagfish, two species of lamprey, and five species of gnathostome fish), and we analyzed the mRNA sequences for the proteins underlying activation of the phototransduction cascade. The molecular phylogenies that we constructed from these sequences are consistent with the 2R WGD model of two rounds of whole genome duplication. Our analysis suggests that agnathans retain an additional representative (that has been lost in gnathostomes) in each of the gene families we studied; the evidence is strong for the G-protein α subunit (GNAT) and the cGMP phosphodiesterase (PDE6), and indicative for the cyclic nucleotide-gated channels (CNGA and CNGB). Two of the species (the hagfish Eptatretus cirrhatus and the lamprey Mordacia mordax) possess only a single class of photoreceptor, simplifying deductions about the composition of cascade protein isoforms utilized in their photoreceptors. For the other lamprey, Geotria australis, analysis of the ratios of transcript levels in downstream and upstream migrant animals permits tentative conclusions to be drawn about the isoforms used in four of the five spectral classes of photoreceptor. Overall, our results suggest that agnathan rod-like photoreceptors utilize the same GNAT1 as gnathostomes, together with a homodimeric PDE6 that may be agnathan-specific, whereas agnathan cone-like photoreceptors utilize a GNAT that may be agnathan-specific, together with the same PDE6C as gnathostomes. These findings help elucidate the evolution of the vertebrate phototransduction cascade from an ancestral chordate phototransduction cascade that existed prior to the vertebrate radiation.
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Affiliation(s)
- Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Hardip Patel
- Genome Discovery Unit, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia Department of Genome Biology, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Aaron Chuah
- Genome Discovery Unit, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Riccardo C Natoli
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia ANU Medical School, Australian National University, Canberra, ACT, Australia
| | - Wayne I L Davies
- School of Animal Biology, University of Western Australia, Perth, WA, Australia Oceans Institute, University of Western Australia, Perth, WA, Australia Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - Nathan S Hart
- School of Animal Biology, University of Western Australia, Perth, WA, Australia Oceans Institute, University of Western Australia, Perth, WA, Australia Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Shaun P Collin
- School of Animal Biology, University of Western Australia, Perth, WA, Australia Oceans Institute, University of Western Australia, Perth, WA, Australia Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - David M Hunt
- School of Animal Biology, University of Western Australia, Perth, WA, Australia Lions Eye Institute, University of Western Australia, Perth, WA, Australia
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van Hazel I, Dungan SZ, Hauser FE, Morrow JM, Endler JA, Chang BSW. A comparative study of rhodopsin function in the great bowerbird (Ptilonorhynchus nuchalis): Spectral tuning and light-activated kinetics. Protein Sci 2016; 25:1308-18. [PMID: 26889650 DOI: 10.1002/pro.2902] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/16/2016] [Accepted: 02/16/2016] [Indexed: 12/18/2022]
Abstract
Rhodopsin is the visual pigment responsible for initiating the phototransduction cascade in vertebrate rod photoreceptors. Although well-characterized in a few model systems, comparative studies of rhodopsin function, particularly for nonmammalian vertebrates are comparatively lacking. Bowerbirds are rare among passerines in possessing a key substitution, D83N, at a site that is otherwise highly conserved among G protein-coupled receptors. While this substitution is present in some dim-light adapted vertebrates, often accompanying another unusual substitution, A292S, its functional relevance in birds is uncertain. To investigate functional effects associated with these two substitutions, we use the rhodopsin gene from the great bowerbird (Ptilonorhynchus nuchalis) as a background for site-directed mutagenesis, in vitro expression and functional characterization. We also mutated these sites in two additional rhodopsins that do not naturally possess N83, chicken and bovine, for comparison. Both sites were found to contribute to spectral blue-shifts, but had opposing effects on kinetic rates. Substitutions at site 83 were found to primarily affect the kinetics of light-activated rhodopsin, while substitutions at site 292 had a larger impact on spectral tuning. The contribution of substitutions at site 83 to spectral tuning in particular depended on genetic background, but overall, the effects of substitutions were otherwise surprisingly additive, and the magnitudes of functional shifts were roughly similar across all three genetic backgrounds. By employing a comparative approach with multiple species, our study provides new insight into the joint impact of sites 83 and 292 on rhodopsin structure-function as well as their evolutionary significance for dim-light vision across vertebrates.
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Affiliation(s)
- Ilke van Hazel
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Sarah Z Dungan
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - Frances E Hauser
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada
| | - James M Morrow
- Department of Cell and Systems Biology, University of Toronto, Canada
| | - John A Endler
- Centre for Integrative Ecology, Deakin University, Australia
| | - Belinda S W Chang
- Department of Ecology and Evolutionary Biology, University of Toronto, Canada.,Department of Cell and Systems Biology, University of Toronto, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, Canada
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Davies WIL, Tamai TK, Zheng L, Fu JK, Rihel J, Foster RG, Whitmore D, Hankins MW. An extended family of novel vertebrate photopigments is widely expressed and displays a diversity of function. Genome Res 2015; 25:1666-79. [PMID: 26450929 PMCID: PMC4617963 DOI: 10.1101/gr.189886.115] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 07/15/2015] [Indexed: 11/24/2022]
Abstract
Light affects animal physiology and behavior more than simply through classical visual, image-forming pathways. Nonvisual photoreception regulates numerous biological systems, including circadian entrainment, DNA repair, metabolism, and behavior. However, for the majority of these processes, the photoreceptive molecules involved are unknown. Given the diversity of photophysiological responses, the question arises whether a single photopigment or a greater diversity of proteins within the opsin superfamily detect photic stimuli. Here, a functional genomics approach identified the full complement of photopigments in a highly light-sensitive model vertebrate, the zebrafish (Danio rerio), and characterized their tissue distribution, expression levels, and biochemical properties. The results presented here reveal the presence of 42 distinct genes encoding 10 classical visual photopigments and 32 nonvisual opsins, including 10 novel opsin genes comprising four new pigment classes. Consistent with the presence of light-entrainable circadian oscillators in zebrafish, all adult tissues examined expressed two or more opsins, including several novel opsins. Spectral and electrophysiological analyses of the new opsins demonstrate that they form functional photopigments, each with unique chromophore-binding and wavelength specificities. This study has revealed a remarkable number and diversity of photopigments in zebrafish, the largest number so far discovered for any vertebrate. Found in amphibians, reptiles, birds, and all three mammalian clades, most of these genes are not restricted to teleosts. Therefore, nonvisual light detection is far more complex than initially appreciated, which has significant biological implications in understanding photoreception in vertebrates.
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Affiliation(s)
- Wayne I L Davies
- School of Animal Biology and University of Western Australia Oceans Institute, University of Western Australia, Perth, Western Australia 6009, Australia; Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - T Katherine Tamai
- Centre for Cell and Molecular Dynamics, Department of Cell and Developmental Biology, University College London, London, WC1E 6DE, United Kingdom
| | - Lei Zheng
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Josephine K Fu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - Jason Rihel
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, United Kingdom
| | - Russell G Foster
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
| | - David Whitmore
- Centre for Cell and Molecular Dynamics, Department of Cell and Developmental Biology, University College London, London, WC1E 6DE, United Kingdom
| | - Mark W Hankins
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DU, United Kingdom
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Salas CA, Yopak KE, Warrington RE, Hart NS, Potter IC, Collin SP. Ontogenetic shifts in brain scaling reflect behavioral changes in the life cycle of the pouched lamprey Geotria australis. Front Neurosci 2015; 9:251. [PMID: 26283894 PMCID: PMC4517384 DOI: 10.3389/fnins.2015.00251] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 07/03/2015] [Indexed: 12/11/2022] Open
Abstract
Very few studies have described brain scaling in vertebrates throughout ontogeny and none in lampreys, one of the two surviving groups of the early agnathan (jawless) stage in vertebrate evolution. The life cycle of anadromous parasitic lampreys comprises two divergent trophic phases, firstly filter-feeding as larvae in freshwater and secondly parasitism as adults in the sea, with the transition marked by a radical metamorphosis. We characterized the growth of the brain during the life cycle of the pouched lamprey Geotria australis, an anadromous parasitic lamprey, focusing on the scaling between brain and body during ontogeny and testing the hypothesis that the vast transitions in behavior and environment are reflected in differences in the scaling and relative size of the major brain subdivisions throughout life. The body and brain mass and the volume of six brain structures of G. australis, representing six points of the life cycle, were recorded, ranging from the early larval stage to the final stage of spawning and death. Brain mass does not increase linearly with body mass during the ontogeny of G. australis. During metamorphosis, brain mass increases markedly, even though the body mass does not increase, reflecting an overall growth of the brain, with particularly large increases in the volume of the optic tectum and other visual areas of the brain and, to a lesser extent, the olfactory bulbs. These results are consistent with the conclusions that ammocoetes rely predominantly on non-visual and chemosensory signals, while adults rely on both visual and olfactory cues.
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Affiliation(s)
- Carlos A Salas
- Neuroecology Group, School of Animal Biology and UWA Oceans Institute, The University of Western Australia Crawley, WA, Australia
| | - Kara E Yopak
- Neuroecology Group, School of Animal Biology and UWA Oceans Institute, The University of Western Australia Crawley, WA, Australia
| | - Rachael E Warrington
- Neuroecology Group, School of Animal Biology and UWA Oceans Institute, The University of Western Australia Crawley, WA, Australia
| | - Nathan S Hart
- Neuroecology Group, School of Animal Biology and UWA Oceans Institute, The University of Western Australia Crawley, WA, Australia
| | - Ian C Potter
- Centre for Fish and Fisheries Research, School of Veterinary and Life Sciences, Murdoch University Murdoch, WA, Australia
| | - Shaun P Collin
- Neuroecology Group, School of Animal Biology and UWA Oceans Institute, The University of Western Australia Crawley, WA, Australia
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Cornide-Petronio ME, Anadón R, Barreiro-Iglesias A, Rodicio MC. Tryptophan hydroxylase and serotonin receptor 1A expression in the retina of the sea lamprey. Exp Eye Res 2015; 135:81-7. [DOI: 10.1016/j.exer.2015.04.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 03/25/2015] [Accepted: 04/25/2015] [Indexed: 11/16/2022]
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You X, Bian C, Zan Q, Xu X, Liu X, Chen J, Wang J, Qiu Y, Li W, Zhang X, Sun Y, Chen S, Hong W, Li Y, Cheng S, Fan G, Shi C, Liang J, Tom Tang Y, Yang C, Ruan Z, Bai J, Peng C, Mu Q, Lu J, Fan M, Yang S, Huang Z, Jiang X, Fang X, Zhang G, Zhang Y, Polgar G, Yu H, Li J, Liu Z, Zhang G, Ravi V, Coon SL, Wang J, Yang H, Venkatesh B, Wang J, Shi Q. Mudskipper genomes provide insights into the terrestrial adaptation of amphibious fishes. Nat Commun 2014; 5:5594. [PMID: 25463417 PMCID: PMC4268706 DOI: 10.1038/ncomms6594] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 10/16/2014] [Indexed: 01/18/2023] Open
Abstract
Mudskippers are amphibious fishes that have developed morphological and physiological adaptations to match their unique lifestyles. Here we perform whole-genome sequencing of four representative mudskippers to elucidate the molecular mechanisms underlying these adaptations. We discover an expansion of innate immune system genes in the mudskippers that may provide defence against terrestrial pathogens. Several genes of the ammonia excretion pathway in the gills have experienced positive selection, suggesting their important roles in mudskippers’ tolerance to environmental ammonia. Some vision-related genes are differentially lost or mutated, illustrating genomic changes associated with aerial vision. Transcriptomic analyses of mudskippers exposed to air highlight regulatory pathways that are up- or down-regulated in response to hypoxia. The present study provides a valuable resource for understanding the molecular mechanisms underlying water-to-land transition of vertebrates. Mudskippers are amphibious fishes that have adapted to live on mudflats. Here, the authors sequence the genomes of four different mudskipper species and highlight genetic changes that may have had an evolutionary role in the water-to-land transition of vertebrates.
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Affiliation(s)
- Xinxin You
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Chao Bian
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Qijie Zan
- Shenzhen Wild Animal Rescue Center, Shenzhen 518040, China
| | - Xun Xu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Xin Liu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jieming Chen
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | | | - Ying Qiu
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Wujiao Li
- Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China
| | - Xinhui Zhang
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Ying Sun
- BGI-Shenzhen, Shenzhen 518083, China
| | - Shixi Chen
- College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
| | - Wanshu Hong
- College of Ocean and Earth Science, Xiamen University, Xiamen 361005, China
| | | | | | | | | | - Jie Liang
- BGI-Shenzhen, Shenzhen 518083, China
| | | | | | - Zhiqiang Ruan
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Jie Bai
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Chao Peng
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Qian Mu
- BGI-Shenzhen, Shenzhen 518083, China
| | - Jun Lu
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Shenzhen BGI Fisheries Sci &Tech Co. Ltd, Shenzhen 518083, China
| | - Mingjun Fan
- Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
| | - Shuang Yang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
| | | | | | | | | | | | - Gianluca Polgar
- Environmental and Life Sciences Programme, Faculty of Science, Universiti Brunei Darussalam, Jln Tungku Link, BE1410 Brunei Darussalam
| | - Hui Yu
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Jia Li
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China
| | - Zhongjian Liu
- Shenzhen Key Laboratory for Orchid Conservation and Utilization of the Orchid Conservation and Research Center of Shenzhen, Shenzhen 518114, China
| | - Guoqiang Zhang
- Shenzhen Key Laboratory for Orchid Conservation and Utilization of the Orchid Conservation and Research Center of Shenzhen, Shenzhen 518114, China
| | - Vydianathan Ravi
- Institute of Molecular and Cell Biology, A*STAR, Biopolis, Singapore 138673, Singapore
| | - Steven L Coon
- Molecular Genomics Laboratory, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jian Wang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] James D. Watson Institute of Genome Science, Hangzhou 310008, China
| | - Huanming Yang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] James D. Watson Institute of Genome Science, Hangzhou 310008, China [3] Princess Al Jawhara Center of Excellence in the Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Byrappa Venkatesh
- Institute of Molecular and Cell Biology, A*STAR, Biopolis, Singapore 138673, Singapore
| | - Jun Wang
- 1] BGI-Shenzhen, Shenzhen 518083, China [2] Princess Al Jawhara Center of Excellence in the Research of Hereditary Disorders, King Abdulaziz University, Jeddah, Saudi Arabia [3] Department of Biology, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Qiong Shi
- 1] Shenzhen Key Lab of Marine Genomics, State Key Laboratory of Agricultural Genomics, Shenzhen 518083, China [2] BGI-Shenzhen, Shenzhen 518083, China [3] Shenzhen BGI Fisheries Sci &Tech Co. Ltd, Shenzhen 518083, China [4] Center for Fish Genomics, BGI-Wuhan, Wuhan 430075, China
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Fletcher LN, Coimbra JP, Rodger J, Potter IC, Gill HS, Dunlop SA, Collin SP. Classification of retinal ganglion cells in the southern hemisphere lampreyGeotria australis(Cyclostomata). J Comp Neurol 2014; 522:750-71. [PMID: 23897624 DOI: 10.1002/cne.23441] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 05/08/2013] [Accepted: 07/18/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Lee Norman Fletcher
- School of Animal Biology; The University of Western Australia; Crawley Western Australia 6009 Australia
- Oceans Institute; The University of Western Australia; Crawley Western Australia 6009 Australia
| | - João Paulo Coimbra
- School of Animal Biology; The University of Western Australia; Crawley Western Australia 6009 Australia
- Oceans Institute; The University of Western Australia; Crawley Western Australia 6009 Australia
| | - Jennifer Rodger
- School of Animal Biology; The University of Western Australia; Crawley Western Australia 6009 Australia
| | - Ian C. Potter
- School of Biological Sciences and Biotechnology; Murdoch University; Murdoch Western Australia 6150 Australia
| | - Howard S. Gill
- School of Biological Sciences and Biotechnology; Murdoch University; Murdoch Western Australia 6150 Australia
| | - Sarah A. Dunlop
- School of Animal Biology; The University of Western Australia; Crawley Western Australia 6009 Australia
| | - Shaun P. Collin
- School of Animal Biology; The University of Western Australia; Crawley Western Australia 6009 Australia
- Oceans Institute; The University of Western Australia; Crawley Western Australia 6009 Australia
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Knott B, Davies WIL, Carvalho LS, Berg ML, Buchanan KL, Bowmaker JK, Bennett ATD, Hunt DM. How parrots see their colours: novelty in the visual pigments of Platycercus elegans. J Exp Biol 2013; 216:4454-61. [DOI: 10.1242/jeb.094136] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Intraspecific differences in retinal physiology have been demonstrated in several vertebrate taxa and are often subject to adaptive evolution. Nonetheless, such differences are currently unknown in birds, despite variations in habitat, behaviour and visual stimuli that might influence spectral sensitivity. The parrot Platycercus elegans is a species complex with extreme plumage colour differences between (and sometimes within) subspecies, making it an ideal candidate for intraspecific differences in spectral sensitivity. Here, the visual pigments of P. elegans were fully characterised through molecular sequencing of five visual opsin genes and measurement of their absorbance spectra using microspectrophotometry. Three of the genes, LWS, SW1 and SWS2, encode for proteins similar to those found in other birds; however, both the RH1 and RH2 pigments had polypeptides with carboxyl termini of different lengths and unusual properties that are unknown previously for any vertebrate visual pigment. Specifically, multiple RH2 transcripts and protein variants (short, medium and long) were identified for the first time that are generated by alternative splicing of downstream coding and non-coding exons. Our work provides the first complete characterisation of the visual pigments of a parrot, perhaps the most colourful order of birds, and moreover suggests more variability in avian eyes than hitherto considered.
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Affiliation(s)
- Ben Knott
- Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia
| | - Wayne I. L. Davies
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- School of Animal Biology and UWA Oceans Institute, University of Western Australia, Perth, WA 6009, Australia
| | - Livia S. Carvalho
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Mathew L. Berg
- Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia
| | - Katherine L. Buchanan
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia
- Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - James K. Bowmaker
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Andrew T. D. Bennett
- Centre for Behavioural Biology, School of Biological Sciences, University of Bristol, Bristol BS8 1UG, UK
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3217, Australia
| | - David M. Hunt
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- School of Animal Biology and UWA Oceans Institute, University of Western Australia, Perth, WA 6009, Australia
- Lions Eye Institute, University of Western Australia, Perth, WA 6009, Australia
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Lagman D, Ocampo Daza D, Widmark J, Abalo XM, Sundström G, Larhammar D. The vertebrate ancestral repertoire of visual opsins, transducin alpha subunits and oxytocin/vasopressin receptors was established by duplication of their shared genomic region in the two rounds of early vertebrate genome duplications. BMC Evol Biol 2013; 13:238. [PMID: 24180662 PMCID: PMC3826523 DOI: 10.1186/1471-2148-13-238] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 10/29/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vertebrate color vision is dependent on four major color opsin subtypes: RH2 (green opsin), SWS1 (ultraviolet opsin), SWS2 (blue opsin), and LWS (red opsin). Together with the dim-light receptor rhodopsin (RH1), these form the family of vertebrate visual opsins. Vertebrate genomes contain many multi-membered gene families that can largely be explained by the two rounds of whole genome duplication (WGD) in the vertebrate ancestor (2R) followed by a third round in the teleost ancestor (3R). Related chromosome regions resulting from WGD or block duplications are said to form a paralogon. We describe here a paralogon containing the genes for visual opsins, the G-protein alpha subunit families for transducin (GNAT) and adenylyl cyclase inhibition (GNAI), the oxytocin and vasopressin receptors (OT/VP-R), and the L-type voltage-gated calcium channels (CACNA1-L). RESULTS Sequence-based phylogenies and analyses of conserved synteny show that the above-mentioned gene families, and many neighboring gene families, expanded in the early vertebrate WGDs. This allows us to deduce the following evolutionary scenario: The vertebrate ancestor had a chromosome containing the genes for two visual opsins, one GNAT, one GNAI, two OT/VP-Rs and one CACNA1-L gene. This chromosome was quadrupled in 2R. Subsequent gene losses resulted in a set of five visual opsin genes, three GNAT and GNAI genes, six OT/VP-R genes and four CACNA1-L genes. These regions were duplicated again in 3R resulting in additional teleost genes for some of the families. Major chromosomal rearrangements have taken place in the teleost genomes. By comparison with the corresponding chromosomal regions in the spotted gar, which diverged prior to 3R, we could time these rearrangements to post-3R. CONCLUSIONS We present an extensive analysis of the paralogon housing the visual opsin, GNAT and GNAI, OT/VP-R, and CACNA1-L gene families. The combined data imply that the early vertebrate WGD events contributed to the evolution of vision and the other neuronal and neuroendocrine functions exerted by the proteins encoded by these gene families. In pouched lamprey all five visual opsin genes have previously been identified, suggesting that lampreys diverged from the jawed vertebrates after 2R.
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Affiliation(s)
- David Lagman
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
| | - Daniel Ocampo Daza
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
| | - Jenny Widmark
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
| | - Xesús M Abalo
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
| | - Görel Sundström
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
- Present address: Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Box 582, SE-75123 Uppsala, Sweden
| | - Dan Larhammar
- Department of Neuroscience, Science for Life Laboratory, Uppsala University, Box 593, SE-75124 Uppsala, Sweden
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Evolution of phototransduction, vertebrate photoreceptors and retina. Prog Retin Eye Res 2013; 36:52-119. [DOI: 10.1016/j.preteyeres.2013.06.001] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 06/02/2013] [Indexed: 01/12/2023]
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Nivison-Smith L, Collin SP, Zhu Y, Ready S, Acosta ML, Hunt DM, Potter IC, Kalloniatis M. Retinal amino acid neurochemistry of the southern hemisphere lamprey, Geotria australis. PLoS One 2013; 8:e58406. [PMID: 23516473 PMCID: PMC3596384 DOI: 10.1371/journal.pone.0058406] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 02/04/2013] [Indexed: 01/01/2023] Open
Abstract
Lampreys are one of the two surviving groups of the agnathan (jawless) stages in vertebrate evolution and are thus ideal candidates for elucidating the evolution of visual systems. This study investigated the retinal amino acid neurochemistry of the southern hemisphere lamprey Geotria australis during the downstream migration of the young, recently-metamorphosed juveniles to the sea and during the upstream migration of the fully-grown and sexually-maturing adults to their spawning areas. Glutamate and taurine were distributed throughout the retina, whilst GABA and glycine were confined to neurons of the inner retina matching patterns seen in most other vertebrates. Glutamine and aspartate immunoreactivity was closely matched to Müller cell morphology. Between the migratory phases, few differences were observed in the distribution of major neurotransmitters i.e. glutamate, GABA and glycine, but changes in amino acids associated with retinal metabolism i.e. glutamine and aspartate, were evident. Taurine immunoreactivity was mostly conserved between migrant stages, consistent with its role in primary cell functions such as osmoregulation. Further investigation of glutamate signalling using the probe agmatine (AGB) to map cation channel permeability revealed entry of AGB into photoreceptors and horizontal cells followed by accumulation in inner retinal neurons. Similarities in AGB profiles between upstream and downstream migrant of G. australis confirmed the conservation of glutamate neurotransmission. Finally, calcium binding proteins, calbindin and calretinin were localized to the inner retina whilst recoverin was localized to photoreceptors. Overall, conservation of major amino acid neurotransmitters and calcium-associated proteins in the lamprey retina confirms these elements as essential features of the vertebrate visual system. On the other hand, metabolic elements of the retina such as neurotransmitter precursor amino acids and Müller cells are more sensitive to environmental changes associated with migration.
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Affiliation(s)
- Lisa Nivison-Smith
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
| | - Shaun P. Collin
- School of Animal Biology and the University of Western Australia Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Yuan Zhu
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
| | - Sarah Ready
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - Monica L. Acosta
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - David M. Hunt
- School of Animal Biology and the University of Western Australia Oceans Institute, University of Western Australia, Crawley, Western Australia, Australia
| | - Ian C. Potter
- School of Biological Sciences and Biotechnology, Murdoch University, Murdoch, Western Australia, Australia
| | - Michael Kalloniatis
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
- Centre for Eye Health, University of New South Wales, Sydney, New South Wales, Australia
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McClements M, Davies WIL, Michaelides M, Young T, Neitz M, MacLaren RE, Moore AT, Hunt DM. Variations in opsin coding sequences cause x-linked cone dysfunction syndrome with myopia and dichromacy. Invest Ophthalmol Vis Sci 2013; 54:1361-9. [PMID: 23322568 DOI: 10.1167/iovs.12-11156] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To determine the role of variant L opsin haplotypes in seven families with Bornholm Eye Disease (BED), a cone dysfunction syndrome with dichromacy and myopia. METHODS Analysis of the opsin genes within the L/M opsin array at Xq28 included cloning and sequencing of an exon 3-5 gene fragment, long range PCR to establish gene order, and quantitative PCR to establish gene copy number. In vitro expression of normal and variant opsins was performed to examine cellular trafficking and spectral sensitivity of pigments. RESULTS All except one of the BED families possessed L opsin genes that contained a rare exon 3 haplotype. The exception was a family with the deleterious Cys203Arg substitution. Two rare exon 3 haplotypes were found and, where determined, these variant opsin genes were in the first position in the array. In vitro expression in transfected cultured neuronal cells showed that the variant opsins formed functional pigments, which trafficked to the cell membranes. The variant opsins were, however, less stable than wild type. CONCLUSIONS It is concluded that the variant L opsin haplotypes underlie BED. The reduction in the amount of variant opsin produced in vitro compared with wild type indicates a possible disease mechanism. Alternatively, the recently identified defective splicing of exon 3 of the variant opsin transcript may be involved. Both mechanisms explain the presence of dichromacy and cone dystrophy. Abnormal pigment may also underlie the myopia that is invariably present in BED subjects.
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Affiliation(s)
- Michelle McClements
- University College London Institute of Ophthalmology, London, United Kingdom
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McClements M, Davies WIL, Michaelides M, Carroll J, Rha J, Mollon JD, Neitz M, MacLaren RE, Moore AT, Hunt DM. X-linked cone dystrophy and colour vision deficiency arising from a missense mutation in a hybrid L/M cone opsin gene. Vision Res 2013; 80:41-50. [PMID: 23337435 DOI: 10.1016/j.visres.2012.12.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 12/20/2012] [Accepted: 12/22/2012] [Indexed: 11/17/2022]
Abstract
In this report, we describe a male subject who presents with a complex phenotype of myopia associated with cone dysfunction and a protan vision deficiency. Retinal imaging demonstrates extensive cone disruption, including the presence of non-waveguiding cones, an overall thinning of the retina, and an irregular mottled appearance of the hyper-reflective band associated with the inner segment ellipsoid portion of the photoreceptor. Mutation screening revealed a novel p.Glu41Lys missense mutation in a hybrid L/M opsin gene. Spectral analysis shows that the mutant opsin fails to form a pigment in vitro and fails to be trafficked to the cell membrane in transfected Neuro2a cells. Extensive sequence and quantitative PCR analysis identifies this mutant gene as the only gene present in the affected subject's L/M opsin gene array, yet the presence of protanopia indicates that the mutant opsin must retain some activity in vivo. To account for this apparent contradiction, we propose that a limited amount of functional pigment is formed within the normal cellular environment of the intact photoreceptor, and that this requires the presence of chaperone proteins that promote stability and normal folding of the mutant protein.
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Davies WIL, Tay BH, Zheng L, Danks JA, Brenner S, Foster RG, Collin SP, Hankins MW, Venkatesh B, Hunt DM. Evolution and functional characterisation of melanopsins in a deep-sea chimaera (elephant shark, Callorhinchus milii). PLoS One 2012; 7:e51276. [PMID: 23251480 PMCID: PMC3522658 DOI: 10.1371/journal.pone.0051276] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 10/31/2012] [Indexed: 01/29/2023] Open
Abstract
Non-visual photoreception in mammals is primarily mediated by two splice variants that derive from a single melanopsin (OPN4M) gene, whose expression is restricted to a subset of retinal ganglion cells. Physiologically, this sensory system regulates the photoentrainment of many biological rhythms, such as sleep via the melatonin endocrine system and pupil constriction. By contrast, melanopsin exists as two distinct lineages in non-mammals, opn4m and opn4x, and is broadly expressed in a wide range of tissue types, including the eye, brain, pineal gland and skin. Despite these findings, the evolution and function of melanopsin in early vertebrates are largely unknown. We, therefore, investigated the complement of opn4 classes present in the genome of a model deep-sea cartilaginous species, the elephant shark (Callorhinchus milii), as a representative vertebrate that resides at the base of the gnathostome (jawed vertebrate) lineage. We reveal that three melanopsin genes, opn4m1, opn4m2 and opn4x, are expressed in multiple tissues of the elephant shark. The two opn4m genes are likely to have arisen as a result of a lineage-specific duplication, whereas “long” and “short” splice variants are generated from a single opn4x gene. By using a heterologous expression system, we suggest that these genes encode functional photopigments that exhibit both “invertebrate-like” bistable and classical “vertebrate-like” monostable biochemical characteristics. We discuss the evolution and function of these melanopsin pigments within the context of the diverse photic and ecological environments inhabited by this chimaerid holocephalan, as well as the origin of non-visual sensory systems in early vertebrates.
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Affiliation(s)
- Wayne I. L. Davies
- School of Animal Biology, University of Western Australia Oceans Institute and Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Boon-Hui Tay
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Biopolis, Singapore
| | - Lei Zheng
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Janine A. Danks
- Comparative Endocrinology and Biochemistry Laboratory, School of Medical Sciences, Health Innovations Research Institute, Royal Melbourne Institute of Technology University, Victoria, Australia
| | - Sydney Brenner
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Biopolis, Singapore
| | - Russell G. Foster
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Shaun P. Collin
- School of Animal Biology, University of Western Australia Oceans Institute and Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Mark W. Hankins
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- * E-mail: (DH); (BV); (MWH)
| | - Byrappa Venkatesh
- Comparative Genomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Biopolis, Singapore
- * E-mail: (DH); (BV); (MWH)
| | - David M. Hunt
- School of Animal Biology, University of Western Australia Oceans Institute and Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
- * E-mail: (DH); (BV); (MWH)
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Davies WIL, Wilkie SE, Cowing JA, Hankins MW, Hunt DM. Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments. Cell Mol Life Sci 2012; 69:2455-64. [PMID: 22349213 PMCID: PMC11115090 DOI: 10.1007/s00018-012-0934-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 01/10/2012] [Accepted: 01/26/2012] [Indexed: 10/14/2022]
Abstract
The long-wavelength-sensitive (LWS) opsins form one of four classes of vertebrate cone visual pigment and exhibit peak spectral sensitivities (λ(max)) that generally range from 525 to 560 nm for rhodopsin/vitamin-A(1) photopigments. Unique amongst the opsin classes, many LWS pigments show anion sensitivity through the interaction of chloride ions with a histidine residue at site 197 (H197) to give a long-wavelength spectral shift in peak sensitivity. Although it has been shown that amino acid substitutions at five sites (180, 197, 277, 285 and 308) are useful in predicting the λ(max) values of the LWS pigment class, some species, such as the elephant shark and most marine mammals, express LWS opsins that possess λ(max) values that are not consistent with this 'five-site' rule, indicating that other interactions may be involved. This study has taken advantage of the natural mutation at the chloride-binding site in the mouse LWS pigment. Through the use of a number of mutant pigments generated by site-directed mutagenesis, a new model has been formulated that takes into account the role of charge and steric properties of the side chains of residues at sites 197 and 308 in the function of the chloride-binding site in determining the peak sensitivity of LWS photopigments.
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Affiliation(s)
- Wayne I. L. Davies
- UCL Institute of Ophthalmology, 11–43 Bath Street, London, EC1V 9EL UK
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU UK
- School of Animal Biology and UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Perth, WA 6009 Australia
| | - Susan E. Wilkie
- UCL Institute of Ophthalmology, 11–43 Bath Street, London, EC1V 9EL UK
| | - Jill A. Cowing
- UCL Institute of Ophthalmology, 11–43 Bath Street, London, EC1V 9EL UK
| | - Mark W. Hankins
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neuroscience, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU UK
| | - David M. Hunt
- UCL Institute of Ophthalmology, 11–43 Bath Street, London, EC1V 9EL UK
- School of Animal Biology and UWA Oceans Institute, University of Western Australia, 35 Stirling Highway, Perth, WA 6009 Australia
- Lions Eye Institute, 2 Verdun Street, Perth, WA 6009 Australia
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DAVIES WAYNEIL, COLLIN SHAUNP, HUNT DAVIDM. Molecular ecology and adaptation of visual photopigments in craniates. Mol Ecol 2012; 21:3121-58. [DOI: 10.1111/j.1365-294x.2012.05617.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rennison DJ, Owens GL, Taylor JS. Opsin gene duplication and divergence in ray-finned fish. Mol Phylogenet Evol 2011; 62:986-1008. [PMID: 22178363 DOI: 10.1016/j.ympev.2011.11.030] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 11/18/2011] [Accepted: 11/21/2011] [Indexed: 11/17/2022]
Abstract
Opsin gene sequences were first reported in the 1980s. The goal of that research was to test the hypothesis that human opsins were members of a single gene family and that variation in human color vision was mediated by mutations in these genes. While the new data supported both hypotheses, the greatest contribution of this work was, arguably, that it provided the data necessary for PCR-based surveys in a diversity of other species. Such studies, and recent whole genome sequencing projects, have uncovered exceptionally large opsin gene repertoires in ray-finned fishes (taxon, Actinopterygii). Guppies and zebrafish, for example, have 10 visual opsin genes each. Here we review the duplication and divergence events that have generated these gene collections. Phylogenetic analyses revealed that large opsin gene repertories in fish have been generated by gene duplication and divergence events that span the age of the ray-finned fishes. Data from whole genome sequencing projects and from large-insert clones show that tandem duplication is the primary mode of opsin gene family expansion in fishes. In some instances gene conversion between tandem duplicates has obscured evolutionary relationships among genes and generated unique key-site haplotypes. We mapped amino acid substitutions at so-called key-sites onto phylogenies and this exposed many examples of convergence. We found that dN/dS values were higher on the branches of our trees that followed gene duplication than on branches that followed speciation events, suggesting that duplication relaxes constraints on opsin sequence evolution. Though the focus of the review is opsin sequence evolution, we also note that there are few clear connections between opsin gene repertoires and variation in spectral environment, morphological traits, or life history traits.
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Affiliation(s)
- Diana J Rennison
- University of Victoria, Department of Biology, Station CSC, Victoria, BC, Canada V8W 3N5
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Owens GL, Rennison DJ, Allison WT, Taylor JS. In the four-eyed fish (Anableps anableps), the regions of the retina exposed to aquatic and aerial light do not express the same set of opsin genes. Biol Lett 2011; 8:86-9. [PMID: 21775314 DOI: 10.1098/rsbl.2011.0582] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The four-eyed fish, Anableps anableps, has eyes with unusual morphological adaptations for simultaneous vision above and below water. The retina, for example, is divided such that one region receives light from the aerial field and the other from the aquatic field. To understand better the adaptive value of this partitioned retina, we characterized photoreceptor distribution using in situ hybridization. Cones expressing sws1, sws2b and rh2-2 (i.e. UV, and short wavelength-sensitive) opsins were found throughout the retina, whereas cones expressing rh2-1 (middle wavelength-sensitive) were largely limited to the ventral retina and those expressing lws (long wavelength-sensitive) opsins were only expressed in the dorsal retina. We next asked when this pattern evolved relative to the 'four-eyed' morphology. We characterized opsin expression in Jenynsia onca, a member of the sister genus to Anableps with typical teleost eye morphology. In J. onca, sws1, sws2b, rh2-2 and rh2-1 opsins were expressed throughout the retina; while lws opsins were not expressed in the ventral retina. Thus, the change that coincides with the evolution of unusual anablepid eye morphology is the loss of rh2-1 expression in the dorsal retina, probably to accommodate increased lws opsin expression. The retinal area that samples aerial light appears not to have changed with respect to photoreceptor transcription.
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Affiliation(s)
- Gregory L Owens
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
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Zeiss CJ, Schwab IR, Murphy CJ, Dubielzig RW. Comparative retinal morphology of the platypus. J Morphol 2011; 272:949-57. [DOI: 10.1002/jmor.10959] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/30/2010] [Accepted: 02/26/2011] [Indexed: 01/03/2023]
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Retinotopy of visual projections to the optic tectum and pretectum in larval sea lamprey. Exp Eye Res 2011; 92:274-81. [PMID: 21295569 DOI: 10.1016/j.exer.2011.01.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 12/20/2010] [Accepted: 01/26/2011] [Indexed: 11/24/2022]
Abstract
The sea lamprey has a complex life cycle with very different larval and adult stages. The eyes of larvae are subcutaneous, lack a differentiated lens and probably work only as an ocellus-like photoreceptor organ, while the well-developed adult eyes are capable of forming images. The larval retina differs greatly from the adult retina and presents a central region with differentiated photoreceptors and a lateral, largely undifferentiated part that grows in the second half of larval life. In the present study, we examined the retinotopy of projections from larval ganglion cells to the optic tectum and pretectum in sea lamprey by using retrograde tract-tracing techniques. In most regions of the tectum, application of the tracer neurobiotin (NB) resulted in labelled ganglion cells in the lateral retina, mostly in the contralateral eye. Ganglion cells of the lateral retina showed a very simple dendritic tree, possibly because of the lack of differentiation of most retinal layers in this region. The retinotectal projection is already retinotopically organized in larvae and follows a pattern similar to that observed in adult lampreys and other vertebrates. Application of NB to the central region of the tectum also led to labelling of a few ganglion cells in the central retina, which were clearly more complex than those in the lateral region, as they had dendrites that branched both in the outer and inner plexiform layers. Application of NB to the medial pretectum led to labelling of ganglion cells in the contralateral central retina. Occasional cells were also labelled in the lateral retina. The differential organization of larval retinal projections to the pretectum and tectum suggests a different role for these projections, which is consistent with the different involvement of these centres in visual behaviour, as determined in adult lampreys. The observations in larvae also reveal very different developmental timetables for these putative functions.
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Mohun SM, Davies WL, Bowmaker JK, Pisani D, Himstedt W, Gower DJ, Hunt DM, Wilkinson M. Identification and characterization of visual pigments in caecilians (Amphibia: Gymnophiona), an order of limbless vertebrates with rudimentary eyes. ACTA ACUST UNITED AC 2011; 213:3586-92. [PMID: 20889838 DOI: 10.1242/jeb.045914] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In comparison with the other amphibian orders, the Anura (frogs) and Urodela (salamanders), knowledge of the visual system of the snake-like Gymnophiona (caecilians) is relatively sparse. Most caecilians are fossorial with, as far as is known any surface activity occurring mainly at night. They have relatively small, poorly developed eyes and might be expected to possess detectable changes in the spectral sensitivity of their visual pigments. Microspectrophotometry was used to determine the spectral sensitivities of the photoreceptors in three species of caecilian, Rhinatrema bivittatum, Geotrypetes seraphini and Typhlonectes natans. Only rod opsin visual pigment, which may be associated with scotopic (dim light) vision when accompanied by other 'rod-specific' components of the phototransduction cascade, was found to be present. Opsin sequences were obtained from the eyes of two species of caecilian, Ichthyophis cf. kohtaoensis and T. natans. These rod opsins were regenerated in vitro with 11-cis retinal to give pigments with spectral sensitivity peaks close to 500 nm. No evidence for cone photoreception, associated with diurnal and colour vision, was detected using molecular and physiological methods. Additionally, visual pigments are short-wavelength shifted in terms of the maximum absorption of light when compared with other amphibian lineages.
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Affiliation(s)
- S M Mohun
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V9EL, UK
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Gustafsson OSE, Ekström P, Kröger RHH. A fibrous membrane suspends the multifocal lens in the eyes of lampreys and African lungfishes. J Morphol 2010; 271:980-9. [PMID: 20623650 DOI: 10.1002/jmor.10849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The sharpness and thus information content of the retinal image in the eye depends on the optical quality of the lens and its accurate positioning in the eye. Multifocal lenses create well-focused color images and are present in the eyes of all vertebrate groups studied to date (mammals, reptiles including birds, amphibians, and ray-finned fishes) and occur even in lampreys, i.e., the most basal vertebrates with well-developed eyes. Results from photoretinoscopy obtained in this study indicate that the Dipnoi (lungfishes), i.e., the closest piscine relatives to tetrapods, also possess multifocal lenses. Suspension of the lens is complex and sophisticated in teleosts (bony fishes) and tetrapods. We studied lens suspension using light and electron microscopy in one species of lamprey (Lampetra fluviatilis) and two species of African lungfish (Protopterus aethiopicus aethiopicus and Protopterus annectens annectens). A fibrous and highly transparent membrane suspends the lens in both of these phylogenetically widely separated vertebrate groups. The membrane attaches to the lens approximately along the lens equator, from where it extends to the ora retinalis. The material forming the membrane is similar in ultrastructure to microfibrils in the zonule fibers of tetrapods. The membrane, possibly in conjunction with the cornea, iris, and vitreous body, seems suitable for keeping the lens in the correct position for well-focused imaging. Suspension of the lens by a multitude of zonule fibers in tetrapods may have evolved from a suspensory membrane similar to that in extant African lungfishes, a structure that seems to have appeared first in the lamprey-like ancestors of allextant vertebrates.
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Affiliation(s)
- Ola S E Gustafsson
- Department of Biology, Lund University, Zoology Building, Helgonavägen 3, 223 62 Lund, Sweden.
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Morrow JM, Chang BSW. The p1D4-hrGFP II expression vector: a tool for expressing and purifying visual pigments and other G protein-coupled receptors. Plasmid 2010; 64:162-9. [PMID: 20627111 DOI: 10.1016/j.plasmid.2010.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/29/2010] [Accepted: 07/05/2010] [Indexed: 11/19/2022]
Abstract
The heterologous expression of membrane proteins such as G protein-coupled receptors can be a notoriously difficult task. We have engineered an expression vector, p1D4-hrGFP II, in order to efficiently express visual pigments in mammalian cell culture. This expression vector is based on pIRES-hrGFP II (Stratagene), with the addition of a C-terminal 1D4 epitope tag for immunoblotting and immunoaffinity purification. This vector employs the CMV promoter and hrGFP II, a co-translated reporter gene. We measured the effectiveness of pIRES-hrGFP II in expressing bovine rhodopsin, and showed a 3.9- to 5.7-fold increase in expression as measured by absorbance spectroscopy as compared with the pMT vector, a common choice for visual pigment expression. We then expressed zebrafish RH2-1 using p1D4-hrGFP II in order to assess its utility in expressing cone opsins, known to be less stable and more difficult to express than bovine rhodopsin. We show a λ(280)/λ(MAX) value of 3.3, one third of that reported in previous studies, suggesting increased expression levels and decreased levels of misfolded, non-functional visual pigment. Finally, we monitored HEK293T cell growth following transfection with pIRES-hrGFP II using fluorescence microscopy to illustrate the benefits of having a co-translated reporter during heterologous expression studies.
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Affiliation(s)
- James M Morrow
- Department of Cell & Systems Biology, University of Toronto, Room 501, Toronto, Ontario, Canada
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Cottrill PB, Davies WL, Semo M, Bowmaker JK, Hunt DM, Jeffery G. Developmental dynamics of cone photoreceptors in the eel. BMC DEVELOPMENTAL BIOLOGY 2009; 9:71. [PMID: 20025774 PMCID: PMC2807862 DOI: 10.1186/1471-213x-9-71] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 12/21/2009] [Indexed: 01/18/2023]
Abstract
BACKGROUND Many fish alter their expressed visual pigments during development. The number of retinal opsins expressed and their type is normally related to the environment in which they live. Eels are known to change the expression of their rod opsins as they mature, but might they also change the expression of their cone opsins? RESULTS The Rh2 and Sws2 opsin sequences from the European Eel were isolated, sequenced and expressed in vitro for an accurate measurement of their lambdamax values. In situ hybridisation revealed that glass eels express only rh2 opsin in their cone photoreceptors, while larger yellow eels continue to express rh2 opsin in the majority of their cones, but also have <5% of cones which express sws2 opsin. Silver eels showed the same expression pattern as the larger yellow eels. This observation was confirmed by qPCR (quantitative polymerase chain reaction). CONCLUSIONS Larger yellow and silver European eels express two different cone opsins, rh2 and sws2. This work demonstrates that only the Rh2 cone opsin is present in younger fish (smaller yellow and glass), the sws2 opsin being expressed additionally only by older fish and only in <5% of cone cells.
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Abstract
Recent findings shed light on the steps underlying the evolution of vertebrate photoreceptors and retina. Vertebrate ciliary photoreceptors are not as wholly distinct from invertebrate rhabdomeric photoreceptors as is sometimes thought. Recent information on the phylogenies of ciliary and rhabdomeric opsins has helped in constructing the likely routes followed during evolution. Clues to the factors that led the early vertebrate retina to become invaginated can be obtained by combining recent knowledge about the origin of the pathway for dark re-isomerization of retinoids with knowledge of the inability of ciliary opsins to undergo photoreversal, along with consideration of the constraints imposed under the very low light levels in the deep ocean. Investigation of the origin of cell classes in the vertebrate retina provides support for the notion that cones, rods and bipolar cells all originated from a primordial ciliary photoreceptor, whereas ganglion cells, amacrine cells and horizontal cells all originated from rhabdomeric photoreceptors. Knowledge of the molecular differences between cones and rods, together with knowledge of the scotopic signalling pathway, provides an understanding of the evolution of rods and of the rods' retinal circuitry. Accordingly, it has been possible to propose a plausible scenario for the sequence of evolutionary steps that led to the emergence of vertebrate photoreceptors and retina.
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Affiliation(s)
- Trevor D Lamb
- ARC Centre of Excellence in Vision Science, The Australian National University, Canberra ACT 0200, Australia.
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Jones MR, Grillner S, Robertson B. Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behavior. J Comp Neurol 2009. [DOI: 10.1002/cne.22154] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Collin SP, Davies WL, Hart NS, Hunt DM. The evolution of early vertebrate photoreceptors. Philos Trans R Soc Lond B Biol Sci 2009; 364:2925-40. [PMID: 19720654 PMCID: PMC2781863 DOI: 10.1098/rstb.2009.0099] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these 'living fossils', we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.
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Affiliation(s)
- Shaun P Collin
- School of Biomedical Sciences, The University of Queensland, Brisbane 4072, Queensland, Australia.
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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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Owens GL, Windsor DJ, Mui J, Taylor JS. A fish eye out of water: ten visual opsins in the four-eyed fish, Anableps anableps. PLoS One 2009; 4:e5970. [PMID: 19551143 PMCID: PMC2696081 DOI: 10.1371/journal.pone.0005970] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 05/27/2009] [Indexed: 11/30/2022] Open
Abstract
The “four-eyed” fish Anableps anableps has numerous morphological adaptations that enable above and below-water vision. Here, as the first step in our efforts to identify molecular adaptations for aerial and aquatic vision in this species, we describe the A. anableps visual opsin repertoire. We used PCR, cloning, and sequencing to survey cDNA using unique primers designed to amplify eight sequences from five visual opsin gene subfamilies, SWS1, SWS2, RH1, RH2, and LWS. We also used Southern blotting to count opsin loci in genomic DNA digested with EcoR1 and BamH1. Phylogenetic analyses confirmed the identity of all opsin sequences and allowed us to map gene duplication and divergence events onto a tree of teleost fish. Each of the gene-specific primer sets produced an amplicon from cDNA, indicating that A. anableps possessed and expressed at least eight opsin genes. A second PCR-based survey of genomic and cDNA uncovered two additional LWS genes. Thus, A. anableps has at least ten visual opsins and all but one were expressed in the eyes of the single adult surveyed. Among these ten visual opsins, two have key site haplotypes not found in other fish. Of particular interest is the A. anableps-specific opsin in the LWS subfamily, S180γ, with a SHYAA five key site haplotype. Although A. anableps has a visual opsin gene repertoire similar to that found in other fishes in the suborder Cyprinodontoidei, the LWS opsin subfamily has two loci not found in close relatives, including one with a key site haplotype not found in any other fish species. A. anableps opsin sequence data will be used to design in situ probes allowing us to test the hypothesis that opsin gene expression differs in the distinct ventral and dorsal retinas found in this species.
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Affiliation(s)
- Gregory L. Owens
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Diana J. Windsor
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - Justin Mui
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
| | - John S. Taylor
- Department of Biology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail:
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