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Lehrstrand J, Davies WIL, Hahn M, Korsgren O, Alanentalo T, Ahlgren U. Illuminating the complete ß-cell mass of the human pancreas- signifying a new view on the islets of Langerhans. Nat Commun 2024; 15:3318. [PMID: 38632302 PMCID: PMC11024155 DOI: 10.1038/s41467-024-47686-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 04/10/2024] [Indexed: 04/19/2024] Open
Abstract
Pancreatic islets of Langerhans play a pivotal role in regulating blood glucose homeostasis, but critical information regarding their mass, distribution and composition is lacking within a whole organ context. Here, we apply a 3D imaging pipeline to generate a complete account of the insulin-producing islets throughout the human pancreas at a microscopic resolution and within a maintained spatial 3D context. These data show that human islets are far more heterogenous than previously accounted for with regards to their size distribution and cellular make up. By deep tissue 3D imaging, this in-depth study demonstrates that 50% of the human insulin-expressing islets are virtually devoid of glucagon-producing α-cells, an observation with significant implications for both experimental and clinical research.
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Affiliation(s)
- Joakim Lehrstrand
- Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Wayne I L Davies
- Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Max Hahn
- Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Olle Korsgren
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
| | - Tomas Alanentalo
- Department of Medical and Translational Biology, Umeå University, Umeå, Sweden
| | - Ulf Ahlgren
- Department of Medical and Translational Biology, Umeå University, Umeå, Sweden.
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2
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Eilertsen M, Dolan DWP, Bolton CM, Karlsen R, Davies WIL, Edvardsen RB, Furmanek T, Sveier H, Migaud H, Helvik JV. Photoreception and transcriptomic response to light during early development of a teleost with a life cycle tightly controlled by seasonal changes in photoperiod. PLoS Genet 2022; 18:e1010529. [PMID: 36508414 PMCID: PMC9744326 DOI: 10.1371/journal.pgen.1010529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 11/15/2022] [Indexed: 12/14/2022] Open
Abstract
Light cues vary along the axis of periodicity, intensity and spectrum and perception of light is dependent on the photoreceptive capacity encoded within the genome and the opsins expressed. A global approach was taken to analyze the photoreceptive capacity and the effect of differing light conditions on a developing teleost prior to first feeding. The transcriptomes of embryos and alevins of Atlantic salmon (Salmo salar) exposed to different light conditions were analyzed, including a developmental series and a circadian profile. The results showed that genes mediating nonvisual photoreception are present prior to hatching when the retina is poorly differentiated. The clock genes were expressed early, but the circadian profile showed that only two clock genes were significantly cycling before first feeding. Few genes were differentially expressed between day and night within a light condition; however, many genes were significantly different between light conditions, indicating that light environment has an impact on the transcriptome during early development. Comparing the transcriptome data from constant conditions to periodicity of white light or different colors revealed overrepresentation of genes related to photoreception, eye development, muscle contraction, degradation of metabolites and cell cycle among others, and in constant light, several clock genes were upregulated. In constant white light and periodicity of green light, genes associated with DNA replication, chromatin remodeling, cell division and DNA repair were downregulated. The study implies a direct influence of light conditions on the transcriptome profile at early developmental stages, by a complex photoreceptive system where few clock genes are cycling.
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Affiliation(s)
- Mariann Eilertsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
- * E-mail: (ME); (JVH)
| | | | - Charlotte M. Bolton
- Institute of Aquaculture, University of Stirling, Stirling, Scotland, United Kingdom
| | - Rita Karlsen
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Wayne I. L. Davies
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
- School of Life Sciences, College of Science, Health and Engineering, La Trobe University, Melbourne, Australia
| | | | | | | | - Herve Migaud
- Institute of Aquaculture, University of Stirling, Stirling, Scotland, United Kingdom
| | - Jon Vidar Helvik
- Department of Biological Sciences, University of Bergen, Bergen, Norway
- * E-mail: (ME); (JVH)
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Nagloo N, Mountford JK, Gundry BJ, Hart NS, Davies WIL, Collin SP, Hemmi JM. Enhanced short-wavelength sensitivity in the blue-tongued skink, Tiliqua rugosa. J Exp Biol 2022; 225:275680. [PMID: 35582824 PMCID: PMC9234500 DOI: 10.1242/jeb.244317] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/11/2022] [Indexed: 11/20/2022]
Abstract
Despite lizards using a wide range of color signals, the limited variation in photoreceptor spectral sensitivities across lizards suggests only weak selection for species-specific, spectral tuning of photoreceptors. Some species, however, have enhanced short wavelength sensitivity, which likely helps with the detection of signals rich in ultraviolet and short wavelengths. In this study, we examined the visual system of Tiliqua rugosa, which has a UV/blue tongue, to gain insight into this species' visual ecology. We used electroretinograms, opsin sequencing and immunohistochemical labelling to characterize whole eye spectral sensitivity and the elements that shape it. Our findings reveal that T. rugosa expresses all five opsins typically found in lizards (SWS1, SWS2, RH1, RH2 and LWS) but possesses greatly enhanced short wavelength sensitivity compared to other diurnal lizards. This enhanced short wavelength sensitivity is characterized by a broadening of the spectral sensitivity curve of the eye towards shorter wavelengths while the peak sensitivity of the eye at longer wavelengths (560 nm) remains similar to other diurnal lizards. While an increased abundance of SWS1 photoreceptors is thought to mediate elevated ultraviolet sensitivity in a couple of other lizard species, SWS1 photoreceptor abundance remains low in our species. Instead, our findings suggest that short-wavelength sensitivity is driven by multiple factors which include a potentially red-shifted SWS1 photoreceptor and the absence of short-wavelength absorbing oil droplets. Examining the coincidence of enhanced short-wavelength sensitivity with blue tongues among lizards of this genus will provide further insight into the co-evolution of conspecific signals and whole-eye spectral sensitivity.
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Affiliation(s)
- Nicolas Nagloo
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,Department of Biology, Lund University, Lund, S-212263, Sweden.,The UWA Oceans Institute, The University of Western Australia, 6009 WA, Australia
| | - Jessica K Mountford
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,The UWA Oceans Institute, The University of Western Australia, 6009 WA, Australia.,Oceans Graduate School, The University of Western Australia, 6009 WA, Australia.,Clinical Genetics and Epidemiology, and Centre for Ophthalmology and Visual Science incorporating the Lions Eye Institute, The University of Western Australia, 6009 WA, Australia
| | - Ben J Gundry
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia
| | - Nathan S Hart
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,School of Natural Sciences, Macquarie University, 2109 NSW, Australia
| | - Wayne I L Davies
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,The UWA Oceans Institute, The University of Western Australia, 6009 WA, Australia.,Oceans Graduate School, The University of Western Australia, 6009 WA, Australia.,Clinical Genetics and Epidemiology, and Centre for Ophthalmology and Visual Science incorporating the Lions Eye Institute, The University of Western Australia, 6009 WA, Australia.,Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, S-90187, Sweden.,School of Agriculture, Biomedicine and Environment, La Trobe University Bundoora, Victoria 3086, Australia
| | - Shaun P Collin
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,The UWA Oceans Institute, The University of Western Australia, 6009 WA, Australia.,Oceans Graduate School, The University of Western Australia, 6009 WA, Australia.,Clinical Genetics and Epidemiology, and Centre for Ophthalmology and Visual Science incorporating the Lions Eye Institute, The University of Western Australia, 6009 WA, Australia.,School of Agriculture, Biomedicine and Environment, La Trobe University Bundoora, Victoria 3086, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, 6009 WA, Australia.,The UWA Oceans Institute, The University of Western Australia, 6009 WA, Australia
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Dakhel S, Davies WIL, Joseph JV, Tomar T, Remeseiro S, Gunhaga L. Chick fetal organ spheroids as a model to study development and disease. BMC Mol Cell Biol 2021; 22:37. [PMID: 34225662 PMCID: PMC8256237 DOI: 10.1186/s12860-021-00374-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Organ culture models have been used over the past few decades to study development and disease. The in vitro three-dimensional (3D) culture system of organoids is well known, however, these 3D systems are both costly and difficult to culture and maintain. As such, less expensive, faster and less complex methods to maintain 3D cell culture models would complement the use of organoids. Chick embryos have been used as a model to study human biology for centuries, with many fundamental discoveries as a result. These include cell type induction, cell competence, plasticity and contact inhibition, which indicates the relevance of using chick embryos when studying developmental biology and disease mechanisms. RESULTS Here, we present an updated protocol that enables time efficient, cost effective and long-term expansion of fetal organ spheroids (FOSs) from chick embryos. Utilizing this protocol, we generated FOSs in an anchorage-independent growth pattern from seven different organs, including brain, lung, heart, liver, stomach, intestine and epidermis. These three-dimensional (3D) structures recapitulate many cellular and structural aspects of their in vivo counterpart organs and serve as a useful developmental model. In addition, we show a functional application of FOSs to analyze cell-cell interaction and cell invasion patterns as observed in cancer. CONCLUSION The establishment of a broad ranging and highly effective method to generate FOSs from different organs was successful in terms of the formation of healthy, proliferating 3D organ spheroids that exhibited organ-like characteristics. Potential applications of chick FOSs are their use in studies of cell-to-cell contact, cell fusion and tumor invasion under defined conditions. Future studies will reveal whether chick FOSs also can be applicable in scientific areas such as viral infections, drug screening, cancer diagnostics and/or tissue engineering.
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Affiliation(s)
- Soran Dakhel
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Wayne I L Davies
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Justin V Joseph
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Tushar Tomar
- PamGene International B.V, Wolvenhoek 10, 5211 HH, 's-Hertogenbosch, The Netherlands
| | - Silvia Remeseiro
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden.,Wallenberg Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine, Umeå University, 901 87, Umeå, Sweden.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Sghari S, Davies WIL, Gunhaga L. Elucidation of Cellular Mechanisms That Regulate the Sustained Contraction and Relaxation of the Mammalian Iris. Invest Ophthalmol Vis Sci 2020; 61:5. [PMID: 32882011 PMCID: PMC7476664 DOI: 10.1167/iovs.61.11.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose In mammals, pupil constriction and dilation form the pupillary light reflex (PLR), which is mediated by both brain-regulated (parasympathetic) and local iris-driven reflexes. To better understand the cellular mechanisms that regulate pupil physiological dynamics via central and local photoreception, we have examined the regulation of the PLR via parasympathetic and local activation, respectively. Methods In this study, the PLR was examined in mouse enucleated eyes ex vivo in real-time under different ionic conditions in response to acetylcholine and/or blue light (480 nm). The use of pupillometry recordings captured the relaxation, contraction, and pupil escape (redilation) processes for 10 minutes up to 1 hour. Results Among others, our results show that ryanodine receptor channels are the main driver for iridal stimulation–contraction coupling, in which extracellular influx of Ca2+ is required for amplification of pupil constriction. Both local and parasympathetic iridal activations are necessary, but not sufficient for sustained pupil constriction. Moreover, the degree of membrane potential repolarization in the dark is correlated with the latency and velocity of iridal constriction. Furthermore, pupil escape is driven by membrane potential hyperpolarization where voltage-gated potassium channels play a crucial role. Conclusions Together, this study presents new mechanisms regulating synchronized pupil dilation and contraction, sustained pupil constriction, iridal stimulation-contraction coupling, and pupil escape.
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Affiliation(s)
- Soufien Sghari
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Wayne I L Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
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Collin SP, Davies WIL. Editorial: Biodiversity of Sensory Systems in Aquatic Vertebrates. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Mountford JK, Davies WIL, Griffiths LR, Yazar S, Mackey DA, Hunt DM. Differential stability of variant OPN1LW gene transcripts in myopic patients. Mol Vis 2019; 25:183-193. [PMID: 30996587 PMCID: PMC6441357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 03/15/2019] [Indexed: 11/03/2022] Open
Abstract
Purpose In Bornholm eye disease, a defect in the splicing of transcripts from a variant OPN1LW opsin gene leads to a depletion in spliced transcript levels and, consequently, a reduction in photopigment in photoreceptors expressing the variant gene. Methods Myopic and age-matched control subjects were drawn from the Western Australian Pregnancy Cohort (Raine) Study and the Norfolk Island Eye Study groups. The OPN1LW opsin gene was amplified using long-range PCR methodology and was fully sequenced. Expression of variant opsins was evaluated using quantitative PCR (qPCR). RNA secondary structure changes arising from identified variants were predicted by modeling. Results Forty-two nucleotide sites were found to vary across the 111 subjects studied. Of these, 15 had not been previously reported, with three present only in myopic individuals. Expression of these variants in transfected human embryonic kidney (HEK293T) cells demonstrated that splicing efficiencies were not affected. However, gene transcripts from two of the three variants were significantly depleted. RNA secondary structure modeling predicted that these single nucleotide changes could affect RNA stability. Conclusions None of the variants identified in myopic individuals appeared to alter the efficiency of transcript splicing. However, two resulted in a significant reduction in the number of spliced and unspliced transcripts, indicating an overall reduction in steady-state transcript stability. Such a change would be expected to result in a reduced amount of photopigment, and this may be a contributing factor in the development of myopia.
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Affiliation(s)
- Jessica K. Mountford
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, WA, Australia,School of Biological Sciences, University of Western Australia, Perth, WA, Australia,UWA Oceans Institute, University of Western Australia, Crawley, WA, Australia,Oceans Graduate School, University of Western Australia, Crawley, WA, Australia
| | - Wayne I. L. Davies
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, WA, Australia,School of Biological Sciences, University of Western Australia, Perth, WA, Australia,UWA Oceans Institute, University of Western Australia, Crawley, WA, Australia,Oceans Graduate School, University of Western Australia, Crawley, WA, Australia
| | - Lyn R. Griffiths
- Genomics Research Centre, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD, Australia
| | - Seyhan Yazar
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, WA, Australia,MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - David A. Mackey
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - David M. Hunt
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, WA, Australia,School of Biological Sciences, University of Western Australia, Perth, WA, Australia
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Hart NS, Mountford JK, Davies WIL, Collin SP, Hunt DM. Visual pigments in a palaeognath bird, the emu Dromaius novaehollandiae: implications for spectral sensitivity and the origin of ultraviolet vision. Proc Biol Sci 2017; 283:rspb.2016.1063. [PMID: 27383819 DOI: 10.1098/rspb.2016.1063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 06/14/2016] [Indexed: 11/12/2022] Open
Abstract
A comprehensive description of the spectral characteristics of retinal photoreceptors in palaeognaths is lacking. Moreover, controversy exists with respect to the spectral sensitivity of the short-wavelength-sensitive-1 (SWS1) opsin-based visual pigment expressed in one type of single cone: previous microspectrophotometric (MSP) measurements in the ostrich (Struthio camelus) suggested a violet-sensitive (VS) SWS1 pigment, but all palaeognath SWS1 opsin sequences obtained to date (including the ostrich) imply that the visual pigment is ultraviolet-sensitive (UVS). In this study, MSP was used to measure the spectral properties of visual pigments and oil droplets in the retinal photoreceptors of the emu (Dromaius novaehollandiae). Results show that the emu resembles most other bird species in possessing four spectrally distinct single cones, as well as double cones and rods. Four cone and a single rod opsin are expressed, each an orthologue of a previously identified pigment. The SWS1 pigment is clearly UVS (wavelength of maximum absorbance [λmax] = 376 nm), with key tuning sites (Phe86 and Cys90) consistent with other vertebrate UVS SWS1 pigments. Palaeognaths would appear, therefore, to have UVS SWS1 pigments. As they are considered to be basal in avian evolution, this suggests that UVS is the most likely ancestral state for birds. The functional significance of a dedicated UVS cone type in the emu is discussed.
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Affiliation(s)
- Nathan S Hart
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Jessica K Mountford
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia Lions Eye Institute, University of Western Australia, Nedlands, Western Australia 6009, Australia
| | - Wayne I L Davies
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia Lions Eye Institute, University of Western Australia, Nedlands, Western Australia 6009, Australia
| | - Shaun P Collin
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Oceans Institute, University of Western Australia, Crawley, Western Australia 6009, Australia Lions Eye Institute, University of Western Australia, Nedlands, Western Australia 6009, Australia
| | - David M Hunt
- School of Animal Biology, University of Western Australia, Crawley, Western Australia 6009, Australia Lions Eye Institute, University of Western Australia, Nedlands, Western Australia 6009, Australia
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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. Sci Adv 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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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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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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Parolin Schnekenberg R, Perkins EM, Miller JW, Davies WIL, D'Adamo MC, Pessia M, Fawcett KA, Sims D, Gillard E, Hudspith K, Skehel P, Williams J, O'Regan M, Jayawant S, Jefferson R, Hughes S, Lustenberger A, Ragoussis J, Jackson M, Tucker SJ, Németh AH. De novo point mutations in patients diagnosed with ataxic cerebral palsy. Brain 2015; 138:1817-32. [PMID: 25981959 PMCID: PMC4572487 DOI: 10.1093/brain/awv117] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/25/2015] [Indexed: 01/06/2023] Open
Abstract
Cerebral palsy is commonly attributed to perinatal asphyxia. However, Schnekenberg et al. describe here four individuals with ataxic cerebral palsy likely due to de novo dominant mutations associated with increased paternal age. Therefore, patients with cerebral palsy should be investigated for genetic causes before the disorder is ascribed to asphyxia. Cerebral palsy is a sporadic disorder with multiple likely aetiologies, but frequently considered to be caused by birth asphyxia. Genetic investigations are rarely performed in patients with cerebral palsy and there is little proven evidence of genetic causes. As part of a large project investigating children with ataxia, we identified four patients in our cohort with a diagnosis of ataxic cerebral palsy. They were investigated using either targeted next generation sequencing or trio-based exome sequencing and were found to have mutations in three different genes, KCNC3, ITPR1 and SPTBN2. All the mutations were de novo and associated with increased paternal age. The mutations were shown to be pathogenic using a combination of bioinformatics analysis and in vitro model systems. This work is the first to report that the ataxic subtype of cerebral palsy can be caused by de novo dominant point mutations, which explains the sporadic nature of these cases. We conclude that at least some subtypes of cerebral palsy may be caused by de novo genetic mutations and patients with a clinical diagnosis of cerebral palsy should be genetically investigated before causation is ascribed to perinatal asphyxia or other aetiologies.
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Affiliation(s)
- Ricardo Parolin Schnekenberg
- 1 Wellcome Trust Centre for Human Genetics, University of Oxford, OX3 7BN, UK 2 Universidade Positivo, School of Medicine, Rua Parigot de Souza 5300, 81280-330, Curitiba, Brazil
| | - Emma M Perkins
- 3 Centre for Integrative Physiology, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Jack W Miller
- 4 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Wayne I L Davies
- 4 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK 5 School of Animal Biology, University of Western Australia, Perth, Australia 6 Section of Physiology & Biochemistry, Department of Experimental Medicine, School of Medicine & Surgery, University of Perugia, P.le Gambuli 1, Edificio D, Piano 106132 San Sisto, Perugia, Italy
| | - Maria Cristina D'Adamo
- 6 Section of Physiology & Biochemistry, Department of Experimental Medicine, School of Medicine & Surgery, University of Perugia, P.le Gambuli 1, Edificio D, Piano 106132 San Sisto, Perugia, Italy
| | - Mauro Pessia
- 6 Section of Physiology & Biochemistry, Department of Experimental Medicine, School of Medicine & Surgery, University of Perugia, P.le Gambuli 1, Edificio D, Piano 106132 San Sisto, Perugia, Italy 7 Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA 17033-0850, USA
| | - Katherine A Fawcett
- 8 CGAT Programme, MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, OX1 3PT, UK
| | - David Sims
- 8 CGAT Programme, MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, OX1 3PT, UK
| | - Elodie Gillard
- 4 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Karl Hudspith
- 4 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Paul Skehel
- 3 Centre for Integrative Physiology, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Jonathan Williams
- 9 Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford, OX3 7LJ, UK
| | - Mary O'Regan
- 10 Fraser of Allander Neurosciences Unit, Royal Hospital for Sick Children, Glasgow G3 8SJ, UK
| | - Sandeep Jayawant
- 11 Department of Paediatrics, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Rosalind Jefferson
- 12 Department of Paediatrics, Royal Berkshire Foundation Trust Hospital, Reading, UK
| | - Sarah Hughes
- 12 Department of Paediatrics, Royal Berkshire Foundation Trust Hospital, Reading, UK
| | - Andrea Lustenberger
- 13 Department of Neuropaediatrics, Development and Rehabilitation, University Children's Hospital, Inselspital, Bern, Switzerland
| | - Jiannis Ragoussis
- 1 Wellcome Trust Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | - Mandy Jackson
- 3 Centre for Integrative Physiology, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - Stephen J Tucker
- 14 Clarendon Laboratory, Department of Physics, University of Oxford, OX1 3PU, UK 15 OXION Initiative in Ion Channels and Disease, University of Oxford, OX1 3PT, UK
| | - Andrea H Németh
- 4 Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK 16 Department of Clinical Genetics, Churchill Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 7LJ, UK
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Lipinski DM, Barnard AR, Singh MS, Martin C, Lee EJ, Davies WIL, MacLaren RE. CNTF Gene Therapy Confers Lifelong Neuroprotection in a Mouse Model of Human Retinitis Pigmentosa. Mol Ther 2015; 23:1308-1319. [PMID: 25896245 DOI: 10.1038/mt.2015.68] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/28/2015] [Indexed: 12/12/2022] Open
Abstract
The long-term outcome of neuroprotection as a therapeutic strategy for preventing cell death in neurodegenerative disorders remains unknown, primarily due to slow disease progression and the inherent difficulty of assessing neuronal survival in vivo. Employing a murine model of retinal disease, we demonstrate that ciliary neurotrophic factor (CNTF) confers life-long protection against photoreceptor degeneration. Repetitive retinal imaging allowed the survival of intrinsically fluorescent cone photoreceptors to be quantified in vivo. Imaging of the visual cortex and assessment of visually-evoked behavioral responses demonstrated that surviving cones retain function and signal correctly to the brain. The mechanisms underlying CNTF-mediated neuroprotection were explored through transcriptome analysis, revealing widespread upregulation of proteolysis inhibitors, which may prevent cellular/extracellular matrix degradation and complement activation in neurodegenerative diseases. These findings provide insights into potential novel therapeutic avenues for diseases such as retinitis pigmentosa and amyotrophic lateral sclerosis, for which CNTF has been evaluated unsuccessfully in clinical trials.
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Affiliation(s)
- Daniel M Lipinski
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Biomedical Research Centre, University of Oxford, Oxford, UK; Department of Ophthalmology, University of Florida, Gainesville, Florida, USA
| | - Alun R Barnard
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Mandeep S Singh
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Chris Martin
- Department of Psychology, The University of Sheffield, Sheffield, UK
| | - Edward J Lee
- Moorfields Eye Hospital & UCL NIHR Biomedical Research Centre for Ophthalmology, London, UK
| | - Wayne I L Davies
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; School of Animal Biology and University of Western Australia Oceans Institute, University of Western Australia, Perth, Australia
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK; Oxford Biomedical Research Centre, University of Oxford, Oxford, UK; Moorfields Eye Hospital & UCL NIHR Biomedical Research Centre for Ophthalmology, London, UK.
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García-Fernández JM, Cernuda-Cernuda R, Davies WIL, Rodgers J, Turton M, Peirson SN, Follett BK, Halford S, Hughes S, Hankins MW, Foster RG. The hypothalamic photoreceptors regulating seasonal reproduction in birds: a prime role for VA opsin. Front Neuroendocrinol 2015; 37:13-28. [PMID: 25448788 DOI: 10.1016/j.yfrne.2014.11.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/25/2014] [Accepted: 11/02/2014] [Indexed: 01/30/2023]
Abstract
Extraretinal photoreceptors located within the medio-basal hypothalamus regulate the photoperiodic control of seasonal reproduction in birds. An action spectrum for this response describes an opsin photopigment with a λmax of ∼ 492 nm. Beyond this however, the specific identity of the photopigment remains unresolved. Several candidates have emerged including rod-opsin; melanopsin (OPN4); neuropsin (OPN5); and vertebrate ancient (VA) opsin. These contenders are evaluated against key criteria used routinely in photobiology to link orphan photopigments to specific biological responses. To date, only VA opsin can easily satisfy all criteria and we propose that this photopigment represents the prime candidate for encoding daylength and driving seasonal breeding in birds. We also show that VA opsin is co-expressed with both gonadotropin-releasing hormone (GnRH) and arginine-vasotocin (AVT) neurons. These new data suggest that GnRH and AVT neurosecretory pathways are endogenously photosensitive and that our current understanding of how these systems are regulated will require substantial revision.
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Affiliation(s)
- José M García-Fernández
- Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain
| | - Rafael Cernuda-Cernuda
- Departamento de Morfología y Biología Celular, Universidad de Oviedo, INEUROPA (Instituto de Neurociencias del Principado de Asturias), Spain
| | - Wayne I L Davies
- School of Animal Biology and University of Western Australia Oceans Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Jessica Rodgers
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Michael Turton
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Stuart N Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Brian K Follett
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.eNuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Steven Hughes
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Mark W Hankins
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom
| | - Russell G Foster
- Sleep and Circadian Neuroscience Institute, Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford OX3 9DU, United Kingdom.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Aslam SA, Davies WIL, Singh MS, Charbel Issa P, Barnard AR, Scott RAH, MacLaren RE. Cone photoreceptor neuroprotection conferred by CNTF in a novel in vivo model of battlefield retinal laser injury. Invest Ophthalmol Vis Sci 2013; 54:5456-65. [PMID: 23744998 DOI: 10.1167/iovs.13-11623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To develop a reproducible laboratory model to simulate a battlefield foveal laser injury and to test potential neuroprotective effects of a single injection treatment that might be administered in a military setting. METHODS Frequency-doubled 532-nm Nd:YAG laser was used to induce a threshold retinal injury bilaterally in transgenic reporter mice that have fluorescent cones. Intravitreal injection of ciliary neurotrophic factor (CNTF) was then administered to the lasered eye and compared with a contralateral sham injection of saline. The effect on fluorescent cone cell survival was quantified using a confocal scanning laser ophthalmoscope (cSLO), TUNEL assays, and quantitative real-time PCR (qPCR). RESULTS At 3 weeks post-laser, cSLO imaging showed that the proportion of surviving cones expressing green fluorescent protein (GFP) was greater in CNTF-treated (54.1 ± 5.15% of baseline count) than in sham-injected eyes (28.7 ± 4.4%), which was accompanied by a reduction in TUNEL-positive cells. This difference in cone survival persisted at the 6-week point (treated, 39.6 ± 3.2% versus sham, 18.0 ± 3.8%). These changes were accompanied by a reduction in TUNEL-positive cells. The Bcl-2/Bax ratio was increased in CNTF-treated eyes at 1 week postlaser exposure relative to controls. CONCLUSIONS A single intravitreal injection of CNTF protein was shown to improve cone survival when administered immediately after laser exposure. Similar treatments with CNTF might also have a role in attenuating retinal laser damage sustained by combat personnel in the military setting.
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Affiliation(s)
- Sher A Aslam
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Levels 5-6 West Wing, University of Oxford, John Radcliffe Hospital, Headley Way, Oxford, United Kingdom
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Abstract
In 1942, Walls described the concept of a 'nocturnal bottleneck' in placental mammals, where these species could survive only by avoiding daytime activity during times in which dinosaurs were the dominant taxon. Walls based this concept of a longer episode of nocturnality in early eutherian mammals by comparing the visual systems of reptiles, birds and all three extant taxa of the mammalian lineage, namely the monotremes, marsupials (now included in the metatherians) and placentals (included in the eutherians). This review describes the status of what has become known as the nocturnal bottleneck hypothesis, giving an overview of the chronobiological patterns of activity. We review the ecological plausibility that the activity patterns of (early) eutherian mammals were restricted to the night, based on arguments relating to endothermia, energy balance, foraging and predation, taking into account recent palaeontological information. We also assess genes, relating to light detection (visual and non-visual systems) and the photolyase DNA protection system that were lost in the eutherian mammalian lineage. Our conclusion presently is that arguments in favour of the nocturnal bottleneck hypothesis in eutherians prevail.
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Affiliation(s)
- Menno P Gerkema
- Centre for Behaviour and Neuroscience, Department of Chronobiology, University of Groningen, Groningen, The Netherlands.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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27
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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28
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
Much is known regarding the evolution of colour vision in nearly every vertebrate class, with the notable exception of the elasmobranchs. While multiple spectrally distinct cone types are found in some rays, sharks appear to possess only a single class of cone and, therefore, may be colour blind. In this study, the visual opsin genes of two wobbegong species, Orectolobus maculatus and Orectolobus ornatus, were isolated to verify the molecular basis of their monochromacy. In both species, only two opsin genes are present, RH1 (rod) and LWS (cone), which provide further evidence to support the concept that sharks possess only a single cone type. Examination of the coding sequences revealed substitutions that account for interspecific variation in the photopigment absorbance spectra, which may reflect the difference in visual ecology between these species.
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Affiliation(s)
- Susan M Theiss
- School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
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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 DOI: 10.1007/s00018-012-0934-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [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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31
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Davies WIL, Turton M, Peirson SN, Follett BK, Halford S, Garcia-Fernandez JM, Sharp PJ, Hankins MW, Foster RG. Vertebrate ancient opsin photopigment spectra and the avian photoperiodic response. Biol Lett 2011; 8:291-4. [PMID: 22031722 PMCID: PMC3297396 DOI: 10.1098/rsbl.2011.0864] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
In mammals, photoreception is restricted to cones, rods and a subset of retinal ganglion cells. By contrast, non-mammalian vertebrates possess many extraocular photoreceptors but in many cases the role of these photoreceptors and their underlying photopigments is unknown. In birds, deep brain photoreceptors have been shown to sense photic changes in daylength (photoperiod) and mediate seasonal reproduction. Nonetheless, the specific identity of the opsin photopigment ‘sensor’ involved has remained elusive. Previously, we showed that vertebrate ancient (VA) opsin is expressed in avian hypothalamic neurons and forms a photosensitive molecule. However, a direct functional link between VA opsin and the regulation of seasonal biology was absent. Here, we report the in vivo and in vitro absorption spectra (λmax = ∼490 nm) for chicken VA photopigments. Furthermore, the spectral sensitivity of these photopigments match the peak absorbance of the avian photoperiodic response (λmax = 492 nm) and permits maximum photon capture within the restricted light environment of the hypothalamus. Such a correspondence argues strongly that VA opsin plays a key role in regulating seasonal reproduction in birds.
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Affiliation(s)
- Wayne I L Davies
- Nuffield Laboratory of Ophthalmology, Oxford University, Oxford, UK
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