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Wang YY, Liang XF, Lu K. Knockout of SWS2 in zebrafish (Danio rerio) reveals its roles in feeding and phototactic behaviors. Gene 2024; 897:148059. [PMID: 38043833 DOI: 10.1016/j.gene.2023.148059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 10/30/2023] [Accepted: 11/30/2023] [Indexed: 12/05/2023]
Abstract
Common ancestor of vertebrates had four cone opsin subfamilies to obtain color vision: ultraviolet-sensitive (SWS1), blue-sensitive (SWS2), middle wavelength sensitive (RH2) and long wavelength sensitive (LWS). Nevertheless, eutherian mammals had lost the SWS2 and RH2 opsins during their nocturnal lifestyle. Many studies had demonstrated the role of SWS1 and LWS cones in feeding, mate choice and skin pigment cell formation. However, the role of SWS2 and RH2 cones remain elusive. In the present study, we used an ideal model visual system, zebrafish, which still have the four cone opsins, to generate a SWS2 knockout zebrafish line. Through various behavioral test, we found that sws2-/- zebrafish larvae exhibited increased food intake compared with WT. Additionally, there were significantly increased the gene expression of phototransduction pathways in sws2-/- zebrafish larvae. Compared to WT, mutant zebrafish showed weaker phototaxis of red light and changed sensitivity of yellow, red and blue lights. But both mutant and WT zebrafish preferred the red light than other wavelengths of light. Taken together, we proposed that SWS2 cone is not necessary for feeding and phototaxis in zebrafish.
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Affiliation(s)
- Yu-Ye Wang
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, Wuhan 430070, China; Engineering Research Center of Green development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan 430070, China
| | - Xu-Fang Liang
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, Wuhan 430070, China; Engineering Research Center of Green development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan 430070, China.
| | - Ke Lu
- College of Fisheries, Chinese Perch Research Center, Huazhong Agricultural University, Wuhan 430070, China; Engineering Research Center of Green development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Wuhan 430070, China
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2
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Sakamoto S, Matsushita Y, Itoigawa A, Ezawa T, Fujitani T, Takakura K, Zhou Y, Zhang G, Grutzner F, Kawamura S, Hayakawa T. Color vision evolution in egg-laying mammals: insights from visual photoreceptors and daily activities of Australian echidnas. ZOOLOGICAL LETTERS 2024; 10:2. [PMID: 38167154 PMCID: PMC10759620 DOI: 10.1186/s40851-023-00224-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 11/29/2023] [Indexed: 01/05/2024]
Abstract
Egg-laying mammals (monotremes) are considered "primitive" due to traits such as oviparity, cloaca, and incomplete homeothermy, all of which they share with reptiles. Two groups of monotremes, the terrestrial echidna (Tachyglossidae) and semiaquatic platypus (Ornithorhynchidae), have evolved highly divergent characters since their emergence in the Cenozoic era. These evolutionary differences, notably including distinct electrosensory and chemosensory systems, result from adaptations to species-specific habitat conditions. To date, very few studies have examined the visual adaptation of echidna and platypus. In the present study, we show that echidna and platypus have different light absorption spectra in their dichromatic visual sensory systems at the molecular level. We analyzed absorption spectra of monotreme color opsins, long-wavelength sensitive opsin (LWS) and short-wavelength sensitive opsin 2 (SWS2). The wavelength of maximum absorbance (λmax) in LWS was 570.2 in short-beaked echidna (Tachyglossus aculeatus) and 560.6 nm in platypus (Ornithorhynchus anatinus); in SWS2, λmax was 451.7 and 442.6 nm, respectively. Thus, the spectral range in echidna color vision is ~ 10 nm longer overall than in platypus. Natural selection analysis showed that the molecular evolution of monotreme color opsins is generally functionally conserved, suggesting that these taxa rely on species-specific color vision. In order to understand the usage of color vision in monotremes, we made 24-h behavioral observations of captive echidnas at warm temperatures and analyzed the resultant ethograms. Echidnas showed cathemeral activity and various behavioral repertoires such as feeding, traveling, digging, and self-grooming without light/dark environment selectivity. Halting (careful) behavior is more frequent in dark conditions, which suggests that echidnas may be more dependent on vision during the day and olfaction at night. Color vision functions have contributed to dynamic adaptations and dramatic ecological changes during the ~ 60 million years of divergent monotreme evolution. The ethogram of various day and night behaviors in captive echidnas also contributes information relevant to habitat conservation and animal welfare in this iconic species, which is locally endangered.
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Affiliation(s)
- Shiina Sakamoto
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yuka Matsushita
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Akihiro Itoigawa
- Department of Agricultural Chemistry, School of Agriculture, Meiji University, Kawasaki, Kanagawa, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Takumi Ezawa
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | | | | | - Yang Zhou
- BGI Research, Shenzhen, China
- BGI Research, Wuhan, China
| | - Guojie Zhang
- Center of Evolutionary & Organismal Biology, Zhejiang University School of Medicine, Hangzhou, China
| | - Frank Grutzner
- The Environment Institute, University of Adelaide, Adelaide, SA, Australia
| | - Shoji Kawamura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan.
| | - Takashi Hayakawa
- Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan.
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3
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Guo J, Chi H, Zhang L, Song S, Rossiter SJ, Liu Y. Convergent evolutionary shifts in rhodopsin retinal release explain shared opsin repertoires in monotremes and crocodilians. Proc Biol Sci 2023; 290:20230530. [PMID: 37040807 PMCID: PMC10089720 DOI: 10.1098/rspb.2023.0530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023] Open
Abstract
The visual ecology of early mammals remains poorly resolved. Studies of ancestral photopigments suggest an ancient transition from nocturnal to more crepuscular conditions. By contrast, the phenotypic shifts following the split of monotremes and therians-which lost their SWS1 and SWS2 opsins, respectively-are less clear. To address this, we obtained new phenotypic data on the photopigments of extant and ancestral monotremes. We then generated functional data for another vertebrate group that shares the same photopigment repertoire as monotremes: the crocodilians. By characterizing resurrected ancient pigments, we show that the ancestral monotreme underwent a dramatic acceleration in its rhodopsin retinal release rate. Moreover, this change was likely mediated by three residue replacements, two of which also arose on the ancestral branch of crocodilians, which exhibit similarly accelerated retinal release. Despite this parallelism in retinal release, we detected minimal to moderate changes in the spectral tuning of cone visual pigments in these groups. Our results imply that ancestral forms of monotremes and crocodilians independently underwent niche expansion to encompass quickly changing light conditions. This scenario-which accords with reported crepuscular activity in extant monotremes-may help account for their loss of the ultraviolet-sensitive SWS1 pigment but retention of the blue-sensitive SWS2.
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Affiliation(s)
- Jinqu Guo
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Hai Chi
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Linghan Zhang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Shengjing Song
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, People's Republic of China
| | - Stephen J Rossiter
- School of Biological and Behavioural Sciences, Queen Mary, University of London, London E1 4NS, UK
| | - Yang Liu
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, People's Republic of China
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Ogawa Y, Shiraki T, Fukada Y, Kojima D. Foxq2 determines blue cone identity in zebrafish. SCIENCE ADVANCES 2021; 7:eabi9784. [PMID: 34613771 PMCID: PMC8494292 DOI: 10.1126/sciadv.abi9784] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 08/13/2021] [Indexed: 05/26/2023]
Abstract
Most vertebrate lineages retain a tetrachromatic visual system, which is supported by a functional combination of spectrally distinct multiple cone photoreceptors, ultraviolet (UV), blue, green, and red cones. The blue cone identity is ensured by selective expression of blue (sws2) opsin, and the mechanism is poorly understood because sws2 gene has been lost in mammalian species such as mouse, whose visual system has been extensively studied. Here, we pursued loss-of-function studies on transcription factors expressed predominantly in zebrafish cone photoreceptors and identified Foxq2 as a blue cone–specific factor driving sws2 gene expression. Foxq2 has dual functions acting as an activator of sws2 transcription and as a suppressor of UV (sws1) opsin transcription in blue cones. A wide range of vertebrate species retain both foxq2 and sws2 genes. We propose that Foxq2-dependent sws2 expression is a prevalent regulatory mechanism that was acquired at the early stage of vertebrate evolution.
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Vivid biofluorescence discovered in the nocturnal Springhare (Pedetidae). Sci Rep 2021; 11:4125. [PMID: 33603032 PMCID: PMC7892538 DOI: 10.1038/s41598-021-83588-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 01/01/2021] [Indexed: 11/24/2022] Open
Abstract
Biofluorescence has been detected in several nocturnal-crepuscular organisms from invertebrates to birds and mammals. Biofluorescence in mammals has been detected across the phylogeny, including the monotreme duck-billed platypus (Ornithorhyncus anatinus), marsupial opossums (Didelphidae), and New World placental flying squirrels (Gluacomys spp.). Here, we document vivid biofluorescence of springhare (Pedetidae) in both museum specimens and captive individuals—the first documented biofluorescence of an Old World placental mammal. We explore the variation in biofluorescence across our sample and characterize its physical and chemical properties. The striking visual patterning and intensity of color shift was unique relative to biofluorescence found in other mammals. We establish that biofluorescence in springhare likely originates within the cuticle of the hair fiber and emanates, at least partially, from several fluorescent porphyrins and potentially one unassigned molecule absent from our standard porphyrin mixture. This discovery further supports the hypothesis that biofluorescence may be ecologically important for nocturnal-crepuscular mammals and suggests that it may be more broadly distributed throughout Mammalia than previously thought.
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6
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Clark WJ, Colombo M. The functional architecture, receptive field characteristics, and representation of objects in the visual network of the pigeon brain. Prog Neurobiol 2020; 195:101781. [DOI: 10.1016/j.pneurobio.2020.101781] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 02/10/2020] [Accepted: 02/19/2020] [Indexed: 01/08/2023]
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7
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Hart NS, Lamb TD, Patel HR, Chuah A, Natoli RC, Hudson NJ, Cutmore SC, Davies WIL, Collin SP, Hunt DM. Visual Opsin Diversity in Sharks and Rays. Mol Biol Evol 2020; 37:811-827. [PMID: 31770430 DOI: 10.1093/molbev/msz269] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The diversity of color vision systems found in extant vertebrates suggests that different evolutionary selection pressures have driven specializations in photoreceptor complement and visual pigment spectral tuning appropriate for an animal's behavior, habitat, and life history. Aquatic vertebrates in particular show high variability in chromatic vision and have become important models for understanding the role of color vision in prey detection, predator avoidance, and social interactions. In this study, we examined the capacity for chromatic vision in elasmobranch fishes, a group that have received relatively little attention to date. We used microspectrophotometry to measure the spectral absorbance of the visual pigments in the outer segments of individual photoreceptors from several ray and shark species, and we sequenced the opsin mRNAs obtained from the retinas of the same species, as well as from additional elasmobranch species. We reveal the phylogenetically widespread occurrence of dichromatic color vision in rays based on two cone opsins, RH2 and LWS. We also confirm that all shark species studied to date appear to be cone monochromats but report that in different species the single cone opsin may be of either the LWS or the RH2 class. From this, we infer that cone monochromacy in sharks has evolved independently on multiple occasions. Together with earlier discoveries in secondarily aquatic marine mammals, this suggests that cone-based color vision may be of little use for large marine predators, such as sharks, pinnipeds, and cetaceans.
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Affiliation(s)
- Nathan S Hart
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Hardip R Patel
- Department of Genome Sciences, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Aaron Chuah
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Riccardo C Natoli
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia.,ANU Medical School, The Australian National University, Canberra, ACT, Australia
| | - Nicholas J Hudson
- School of Agriculture and Food Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Scott C Cutmore
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Wayne I L Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Bundoora, VIC, Australia
| | - David M Hunt
- School of Biological Sciences, The University of Western Australia, Crawley, WA, Australia.,Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Crawley, WA, Australia
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Patel D, Barnes JE, Davies WIL, Stenkamp DL, Patel JS. Short-wavelength-sensitive 2 (Sws2) visual photopigment models combined with atomistic molecular simulations to predict spectral peaks of absorbance. PLoS Comput Biol 2020; 16:e1008212. [PMID: 33085657 PMCID: PMC7605715 DOI: 10.1371/journal.pcbi.1008212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 11/02/2020] [Accepted: 09/21/2020] [Indexed: 12/02/2022] Open
Abstract
For many species, vision is one of the most important sensory modalities for mediating essential tasks that include navigation, predation and foraging, predator avoidance, and numerous social behaviors. The vertebrate visual process begins when photons of the light interact with rod and cone photoreceptors that are present in the neural retina. Vertebrate visual photopigments are housed within these photoreceptor cells and are sensitive to a wide range of wavelengths that peak within the light spectrum, the latter of which is a function of the type of chromophore used and how it interacts with specific amino acid residues found within the opsin protein sequence. Minor differences in the amino acid sequences of the opsins are known to lead to large differences in the spectral peak of absorbance (i.e. the λmax value). In our prior studies, we developed a new approach that combined homology modeling and molecular dynamics simulations to gather structural information associated with chromophore conformation, then used it to generate statistical models for the accurate prediction of λmax values for photopigments derived from Rh1 and Rh2 amino acid sequences. In the present study, we test our novel approach to predict the λmax of phylogenetically distant Sws2 cone opsins. To build a model that can predict the λmax using our approach presented in our prior studies, we selected a spectrally-diverse set of 11 teleost Sws2 photopigments for which both amino acid sequence information and experimentally measured λmax values are known. The final first-order regression model, consisting of three terms associated with chromophore conformation, was sufficient to predict the λmax of Sws2 photopigments with high accuracy. This study further highlights the breadth of our approach in reliably predicting λmax values of Sws2 cone photopigments, evolutionary-more distant from template bovine RH1, and provided mechanistic insights into the role of known spectral tuning sites.
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Affiliation(s)
- Dharmeshkumar Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States of America
| | - Jonathan E. Barnes
- Department of Physics, University of Idaho, Moscow, ID, United States of America
| | - Wayne I. L. Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
- School of Biological Sciences, University of Western Australia, Perth, WA, Australia
- The Oceans Graduate School, University of Western Australia, Perth, WA, Australia
- The Oceans Institute, University of Western Australia, Perth, WA, Australia
- Lions Eye Institute, University of Western Australia, Perth, WA, Australia
| | - Deborah L. Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States of America
- Institute for Bioinformatics and Evolutionary Biology, University of Idaho, Moscow, ID, United States of America
| | - Jagdish Suresh Patel
- Institute for Modeling Collaboration and Innovation (IMCI), University of Idaho, Moscow, ID, United States of America
- Department of Biological Sciences, University of Idaho, Moscow, ID, United States of America
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9
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Feodorova Y, Falk M, Mirny LA, Solovei I. Viewing Nuclear Architecture through the Eyes of Nocturnal Mammals. Trends Cell Biol 2020; 30:276-289. [PMID: 31980345 DOI: 10.1016/j.tcb.2019.12.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/10/2019] [Accepted: 12/19/2019] [Indexed: 01/09/2023]
Abstract
The cell nucleus is a remarkably well-organized organelle with membraneless but distinct compartments of various functions. The largest of them, euchromatin and heterochromatin, are spatially segregated in such a way that the transcriptionally active genome occupies the nuclear interior, whereas silent genomic loci are preferentially associated with the nuclear envelope. This rule is broken by rod photoreceptor cells of nocturnal mammals, in which the two major compartments have inverted positions. The inversion and dense compaction of heterochromatin converts these nuclei into microlenses that focus light and facilitate nocturnal vision. As is often the case in biology, when a mutation helps to understand normal processes and structures, inverted nuclei have served as a tool to unravel general principles of nuclear organization, including mechanisms of heterochromatin tethering to the nuclear envelope, autonomous behavior of small genomic segments, and euchromatin-heterochromatin segregation.
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Affiliation(s)
- Yana Feodorova
- Biozentrum, Ludwig-Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany; Department of Medical Biology, Medical University-Plovdiv, Boulevard Vasil Aprilov 15A, Plovdiv 4000, Bulgaria
| | - Martin Falk
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Physics, University of Chicago, 929 E 57th St, Chicago, IL 60637, USA
| | - Leonid A Mirny
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Irina Solovei
- Biozentrum, Ludwig-Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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10
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Abstract
There are four cone morphologies in zebrafish, corresponding to UV (U), blue (B), green (G), and red (R)-sensing types; yet genetically, eight cone opsins are expressed. How eight opsins are physiologically siloed in four cone types is not well understood, and in larvae, cone physiological spectral peaks are unstudied. We use a spectral model to infer cone wavelength peaks, semisaturation irradiances, and saturation amplitudes from electroretinogram (ERG) datasets composed of multi-wavelength, multi-irradiance, aspartate-isolated, cone-PIII signals, as compiled from many 5- to 12-day larvae and 8- to 18-month-old adult eyes isolated from wild-type (WT) or roy orbison (roy) strains. Analysis suggests (in nm) a seven-cone, U-360/B1-427/B2-440/G1-460/G3-476/R1-575/R2-556, spectral physiology in WT larvae but a six-cone, U-349/B1-414/G3-483/G4-495/R1-572/R2-556, structure in WT adults. In roy larvae, there is a five-cone structure: U-373/B2-440/G1-460/R1-575/R2-556; in roy adults, there is a four-cone structure, B1-410/G3-482/R1-571/R2-556. Existence of multiple B, G, and R types is inferred from shifts in peaks with red or blue backgrounds. Cones were either high or low semisaturation types. The more sensitive, low semisaturation types included U, B1, and G1 cones [3.0–3.6 log(quanta·μm−2·s−1)]. The less sensitive, high semisaturation types were B2, G3, G4, R1, and R2 types [4.3-4.7 log(quanta·μm−2·s−1)]. In both WT and roy, U- and B- cone saturation amplitudes were greater in larvae than in adults, while G-cone saturation levels were greater in adults. R-cone saturation amplitudes were the largest (50–60% of maximal dataset amplitudes) and constant throughout development. WT and roy larvae differed in cone signal levels, with lesser UV- and greater G-cone amplitudes occurring in roy, indicating strain variation in physiological development of cone signals. These physiological measures of cone types suggest chromatic processing in zebrafish involves at least four to seven spectral signal processing pools.
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11
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Liu DW, Wang FY, Lin JJ, Thompson A, Lu Y, Vo D, Yan HY, Zakon H. The Cone Opsin Repertoire of Osteoglossomorph Fishes: Gene Loss in Mormyrid Electric Fish and a Long Wavelength-Sensitive Cone Opsin That Survived 3R. Mol Biol Evol 2019; 36:447-457. [PMID: 30590689 DOI: 10.1093/molbev/msy241] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Vertebrates have four classes of cone opsin genes derived from two rounds of genome duplication. These are short wavelength sensitive 1(SWS1), short wavelength sensitive 2(SWS2), medium wavelength sensitive (RH2), and long wavelength sensitive (LWS). Teleosts had another genome duplication at their origin and it is believed that only one of each cone opsin survived the ancestral teleost duplication event. We tested this by examining the retinal cones of a basal teleost group, the osteoglossomorphs. Surprisingly, this lineage has lost the typical vertebrate green-sensitive RH2 opsin gene and, instead, has a duplicate of the LWS opsin that is green sensitive. This parallels the situation in mammalian evolution in which the RH2 opsin gene was lost in basal mammals and a green-sensitive opsin re-evolved in Old World, and independently in some New World, primates from an LWS opsin gene. Another group of fish, the characins, possess green-sensitive LWS cones. Phylogenetic analysis shows that the evolution of green-sensitive LWS opsins in these two teleost groups derives from a common ancestral LWS opsin that acquired green sensitivity. Additionally, the nocturnally active African weakly electric fish (Mormyroideae), which are osteoglossomorphs, show a loss of the SWS1 opsin gene. In comparison with the independently evolved nocturnally active South American weakly electric fish (Gymnotiformes) with a functionally monochromatic LWS opsin cone retina, the presence of SWS2, LWS, and LWS2 cone opsins in mormyrids suggests the possibility of color vision.
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Affiliation(s)
- Da-Wei Liu
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli, Taiwan
| | - Feng-Yu Wang
- Taiwan Ocean Research Institute, National Applied Research Laboratories, Kaohsiung, Taiwan
| | - Jinn-Jy Lin
- Biodiversity Research Center, Academia Sinica, Nankang, Taipei, Taiwan
| | - Ammon Thompson
- Department of Integrative Biology, The University of Texas, Austin, TX
| | - Ying Lu
- Department of Integrative Biology, The University of Texas, Austin, TX.,Department of Neuroscience, The University of Texas, Austin, TX
| | - Derek Vo
- Department of Integrative Biology, The University of Texas, Austin, TX
| | - Hong Young Yan
- National Museum of Marine Biology and Aquarium, Chencheng, Pingtung, Taiwan
| | - Harold Zakon
- Department of Integrative Biology, The University of Texas, Austin, TX.,Department of Neuroscience, The University of Texas, Austin, TX
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12
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Liu Y, Chi H, Li L, Rossiter SJ, Zhang S. Molecular Data Support an Early Shift to an Intermediate-Light Niche in the Evolution of Mammals. Mol Biol Evol 2019; 35:1130-1134. [PMID: 29462332 DOI: 10.1093/molbev/msy019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The visual ability and associated photic niche of early mammals is debated. The theory that ancestral mammals were nocturnal is supported by diverse adaptations. However, others argue that photopigment repertoires of early mammals are more consistent with a crepuscular niche, and support for this also comes from inferred spectral tuning of middle/long wavelength-sensitive (M/LWS) opsin sequences. Functional studies have suggested that the M/LWS pigment in the ancestor of Mammalia was either red- or green-sensitive; however, these were based on outdated phylogenies with key lineages omitted. By performing the most detailed study to date of middle/long-wave mammalian color vision, we provide the first experimental evidence that the M/LWS pigment of amniotes underwent a 9-nm spectral shift towards shorter wavelengths in the Mammalia ancestor, exceeding predictions from known critical sites. Our results suggest early mammals were yellow-sensitive, possibly representing an adaptive trade-off for both crepuscular (twilight) and nocturnal (moonlight) niches.
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Affiliation(s)
- Yang Liu
- Key Laboratory of Zoonosis of Liaoning Province, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Hai Chi
- Key Laboratory of Zoonosis of Liaoning Province, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Longfei Li
- Key Laboratory of Zoonosis of Liaoning Province, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Stephen J Rossiter
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Shuyi Zhang
- Key Laboratory of Zoonosis of Liaoning Province, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
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13
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Wu J, Jiao H, Simmons NB, Lu Q, Zhao H. Testing the sensory trade-off hypothesis in New World bats. Proc Biol Sci 2018; 285:rspb.2018.1523. [PMID: 30158315 DOI: 10.1098/rspb.2018.1523] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/04/2018] [Indexed: 01/03/2023] Open
Abstract
Detection of evolutionary shifts in sensory systems is challenging. By adopting a molecular approach, our earlier study proposed a sensory trade-off hypothesis between a loss of colour vision and an origin of high-duty-cycle (HDC) echolocation in Old World bats. Here, we test the hypothesis in New World bats, which include HDC echolocators that are distantly related to Old World HDC echolocators, as well as vampire bats, which have an infrared sensory system apparently unique among bats. Through sequencing the short-wavelength opsin gene (SWS1) in 16 species (29 individuals) of New World bats, we identified a novel SWS1 polymorphism in an HDC echolocator: one allele is pseudogenized but the other is intact, while both alleles are either intact or pseudogenized in other individuals. Strikingly, both alleles were found to be pseudogenized in all three vampire bats. Since pseudogenization, transcriptional or translational changes could separately result in functional loss of a gene, a pseudogenized SWS1 indicates a loss of dichromatic colour vision in bats. Thus, the same sensory trade-off appears to have repeatedly occurred in the two divergent lineages of HDC echolocators, and colour vision may have also been traded off against the infrared sense in vampire bats.
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Affiliation(s)
- Jinwei Wu
- Department of Ecology and Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Hengwu Jiao
- Department of Ecology and Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Nancy B Simmons
- Department of Mammalogy, American Museum of Natural History, New York, NY 10024, USA
| | - Qin Lu
- Department of Ecology and Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Huabin Zhao
- Department of Ecology and Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, People's Republic of China
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Musser JM, Arendt D. Loss and gain of cone types in vertebrate ciliary photoreceptor evolution. Dev Biol 2017; 431:26-35. [DOI: 10.1016/j.ydbio.2017.08.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 01/09/2023]
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15
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Hanna ZR, Henderson JB, Wall JD, Emerling CA, Fuchs J, Runckel C, Mindell DP, Bowie RCK, DeRisi JL, Dumbacher JP. Northern Spotted Owl (Strix occidentalis caurina) Genome: Divergence with the Barred Owl (Strix varia) and Characterization of Light-Associated Genes. Genome Biol Evol 2017; 9:2522-2545. [PMID: 28992302 PMCID: PMC5629816 DOI: 10.1093/gbe/evx158] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 12/20/2022] Open
Abstract
We report here the assembly of a northern spotted owl (Strix occidentalis caurina) genome. We generated Illumina paired-end sequence data at 90× coverage using nine libraries with insert lengths ranging from ∼250 to 9,600 nt and read lengths from 100 to 375 nt. The genome assembly is comprised of 8,108 scaffolds totaling 1.26 × 109 nt in length with an N50 length of 3.98 × 106 nt. We calculated the genome-wide fixation index (FST) of S. o. caurina with the closely related barred owl (Strix varia) as 0.819. We examined 19 genes that encode proteins with light-dependent functions in our genome assembly as well as in that of the barn owl (Tyto alba). We present genomic evidence for loss of three of these in S. o. caurina and four in T. alba. We suggest that most light-associated gene functions have been maintained in owls and their loss has not proceeded to the same extent as in other dim-light-adapted vertebrates.
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Affiliation(s)
- Zachary R. Hanna
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
- Department of Integrative Biology, University of California, Berkeley, California, USA
- Department of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, California, USA
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, California, USA
| | - James B. Henderson
- Department of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, California, USA
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, California, USA
| | - Jeffrey D. Wall
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
- Department of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, California, USA
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, California, USA
- Institute for Human Genetics, University of California, San Francisco, California, USA
| | - Christopher A. Emerling
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Jérôme Fuchs
- Department of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, California, USA
- UMR 7205 Institut de Systématique, Evolution, Biodiversité, CNRS, MNHN, UPMC, EPHE, Sorbonne Universités, Muséum National d’Histoire Naturelle, Paris, France
| | - Charles Runckel
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
- Runckel & Associates, Portland, Oregon, USA
| | - David P. Mindell
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
| | - Rauri C. K. Bowie
- Museum of Vertebrate Zoology, University of California, Berkeley, California, USA
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Joseph L. DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, California, USA
- Howard Hughes Medical Institute, Bethesda, Maryland, USA
| | - John P. Dumbacher
- Department of Ornithology & Mammalogy, California Academy of Sciences, San Francisco, California, USA
- Center for Comparative Genomics, California Academy of Sciences, San Francisco, California, USA
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16
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Carvalho LS, Pessoa DMA, Mountford JK, Davies WIL, Hunt DM. The Genetic and Evolutionary Drives behind Primate Color Vision. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00034] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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17
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Abstract
The recent availability of multiple avian genomes has laid the foundation for a huge variety of comparative genomics analyses including scans for changes and signatures of selection that arose from adaptions to new ecological niches. Nocturnal adaptation in birds, unlike in mammals, is comparatively recent, a fact that makes birds good candidates for identifying early genetic changes that support adaptation to dim-light environments. In this review, we give examples of comparative genomics analyses that could shed light on mechanisms of adaptation to nocturnality. We present advantages and disadvantages of both "data-driven" and "hypothesis-driven" approaches that lead to the discovery of candidate genes and genetic changes promoting nocturnality. We anticipate that the accessibility of multiple genomes from the Genome 10K Project will allow a better understanding of evolutionary mechanisms and adaptation in general.
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Affiliation(s)
- Diana Le Duc
- Medical Faculty, Rudolf Schönheimer Institute of Biochemistry, University of Leipzig, Leipzig, Germany.,Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Torsten Schöneberg
- Medical Faculty, Rudolf Schönheimer Institute of Biochemistry, University of Leipzig, Leipzig, Germany
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Sotolongo-Lopez M, Alvarez-Delfin K, Saade CJ, Vera DL, Fadool JM. Genetic Dissection of Dual Roles for the Transcription Factor six7 in Photoreceptor Development and Patterning in Zebrafish. PLoS Genet 2016; 12:e1005968. [PMID: 27058886 PMCID: PMC4825938 DOI: 10.1371/journal.pgen.1005968] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 03/09/2016] [Indexed: 11/30/2022] Open
Abstract
The visual system of a particular species is highly adapted to convey detailed ecological and behavioral information essential for survival. The consequences of structural mutations of opsins upon spectral sensitivity and environmental adaptation have been studied in great detail, but lacking is knowledge of the potential influence of alterations in gene regulatory networks upon the diversity of cone subtypes and the variation in the ratio of rods and cones observed in numerous diurnal and nocturnal species. Exploiting photoreceptor patterning in cone-dominated zebrafish, we uncovered two independent mechanisms by which the sine oculis homeobox homolog 7 (six7) regulates photoreceptor development. In a genetic screen, we isolated the lots-of-rods-junior (ljrp23ahub) mutation that resulted in an increased number and uniform distribution of rods in otherwise normal appearing larvae. Sequence analysis, genome editing using TALENs and knockdown strategies confirm ljrp23ahub as a hypomorphic allele of six7, a teleost orthologue of six3, with known roles in forebrain patterning and expression of opsins. Based on the lack of predicted protein-coding changes and a deletion of a conserved element upstream of the transcription start site, a cis-regulatory mutation is proposed as the basis of the reduced expression of six7 in ljrp23ahub. Comparison of the phenotypes of the hypomorphic and knock-out alleles provides evidence of two independent roles in photoreceptor development. EdU and PH3 labeling show that the increase in rod number is associated with extended mitosis of photoreceptor progenitors, and TUNEL suggests that the lack of green-sensitive cones is the result of cell death of the cone precursor. These data add six7 to the small but growing list of essential genes for specification and patterning of photoreceptors in non-mammalian vertebrates, and highlight alterations in transcriptional regulation as a potential source of photoreceptor variation across species.
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Affiliation(s)
- Mailin Sotolongo-Lopez
- Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America
| | - Karen Alvarez-Delfin
- Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America
| | - Carole J. Saade
- Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America
- Program in Neuroscience, The Florida State University, Tallahassee, Florida, United States of America
| | - Daniel L. Vera
- Center for Genomics and Personalized Medicine, The Florida State University, Tallahassee, Florida, United States of America
| | - James M. Fadool
- Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America
- Program in Neuroscience, The Florida State University, Tallahassee, Florida, United States of America
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19
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Evolution of phototransduction, vertebrate photoreceptors and retina. Prog Retin Eye Res 2013; 36:52-119. [DOI: 10.1016/j.preteyeres.2013.06.001] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 06/02/2013] [Indexed: 01/12/2023]
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Abstract
AbstractS cones expressing the short wavelength-sensitive type 1 (SWS1) class of visual pigment generally form only a minority type of cone photoreceptor within the vertebrate duplex retina. Hence, their primary role is in color vision, not in high acuity vision. In mammals, S cones may be present as a constant fraction of the cones across the retina, may be restricted to certain regions of the retina or may form a gradient across the retina, and in some species, there is coexpression of SWS1 and the long wavelength-sensitive (LWS) class of pigment in many cones. During retinal development, SWS1 opsin expression generally precedes that of LWS opsin, and evidence from genetic studies indicates that the S cone pathway may be the default pathway for cone development. With the notable exception of the cartilaginous fishes, where S cones appear to be absent, they are present in representative species from all other vertebrate classes. S cone loss is not, however, uncommon; they are absent from most aquatic mammals and from some but not all nocturnal terrestrial species. The peak spectral sensitivity of S cones depends on the spectral characteristics of the pigment present. Evidence from the study of agnathans and teleost fishes indicates that the ancestral vertebrate SWS1 pigment was ultraviolet (UV) sensitive with a peak around 360 nm, but this has shifted into the violet region of the spectrum (>380 nm) on many separate occasions during vertebrate evolution. In all cases, the shift was generated by just one or a few replacements in tuning-relevant residues. Only in the avian lineage has tuning moved in the opposite direction, with the reinvention of UV-sensitive pigments.
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Gerkema MP, Davies WIL, Foster RG, Menaker M, Hut RA. The nocturnal bottleneck and the evolution of activity patterns in mammals. Proc Biol Sci 2013; 280:20130508. [PMID: 23825205 DOI: 10.1098/rspb.2013.0508] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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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22
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Losses of functional opsin genes, short-wavelength cone photopigments, and color vision--a significant trend in the evolution of mammalian vision. Vis Neurosci 2013; 30:39-53. [PMID: 23286388 DOI: 10.1017/s0952523812000429] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
All mammalian cone photopigments are derived from the operation of representatives from two opsin gene families (SWS1 and LWS in marsupial and eutherian mammals; SWS2 and LWS in monotremes), a process that produces cone pigments with respective peak sensitivities in the short and middle-to-long wavelengths. With the exception of a number of primate taxa, the modal pattern for mammals is to have two types of cone photopigment, one drawn from each of the gene families. In recent years, it has been discovered that the SWS1 opsin genes of a widely divergent collection of eutherian mammals have accumulated mutational changes that render them nonfunctional. This alteration reduces the retinal complements of these species to a single cone type, thus rendering ordinary color vision impossible. At present, several dozen species from five mammalian orders have been identified as falling into this category, but the total number of mammalian species that have lost short-wavelength cones in this way is certain to be much larger, perhaps reaching as high as 10% of all species. A number of circumstances that might be used to explain this widespread cone loss can be identified. Among these, the single consistent fact is that the species so affected are nocturnal or, if they are not technically nocturnal, they at least feature retinal organizations that are typically associated with that lifestyle. At the same time, however, there are many nocturnal mammals that retain functional short-wavelength cones. Nocturnality thus appears to set the stage for loss of functional SWS1 opsin genes in mammals, but it cannot be the sole circumstance.
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23
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Functional characterization of the rod visual pigment of the echidna (Tachyglossus aculeatus), a basal mammal. Vis Neurosci 2012; 29:211-7. [PMID: 22874131 DOI: 10.1017/s0952523812000223] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Monotremes are the most basal egg-laying mammals comprised of two extant genera, which are largely nocturnal. Visual pigments, the first step in the sensory transduction cascade in photoreceptors of the eye, have been examined in a variety of vertebrates, but little work has been done to study the rhodopsin of monotremes. We isolated the rhodopsin gene of the nocturnal short-beaked echidna (Tachyglossus aculeatus) and expressed and functionally characterized the protein in vitro. Three mutants were also expressed and characterized: N83D, an important site for spectral tuning and metarhodopsin kinetics, and two sites with amino acids unique to the echidna (T158A and F169A). The λ(max) of echidna rhodopsin (497.9 ± 1.1 nm) did not vary significantly in either T158A (498.0 ± 1.3 nm) or F169A (499.4 ± 0.1 nm) but was redshifted in N83D (503.8 ± 1.5 nm). Unlike other mammalian rhodopsins, echidna rhodopsin did react when exposed to hydroxylamine, although not as fast as cone opsins. The retinal release rate of light-activated echidna rhodopsin, as measured by fluorescence spectroscopy, had a half-life of 9.5 ± 2.6 min-1, which is significantly shorter than that of bovine rhodopsin. The half-life of the N83D mutant was 5.1 ± 0.1 min-1, even shorter than wild type. Our results show that with respect to hydroxylamine sensitivity and retinal release, the wild-type echidna rhodopsin displays major differences to all previously characterized mammalian rhodopsins and appears more similar to other nonmammalian vertebrate rhodopsins such as chicken and anole. However, our N83D mutagenesis results suggest that this site may mediate adaptation in the echidna to dim light environments, possibly via increased stability of light-activated intermediates. This study is the first characterization of a rhodopsin from a most basal mammal and indicates that there might be more functional variation in mammalian rhodopsins than previously assumed.
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DAVIES WAYNEIL, COLLIN SHAUNP, HUNT DAVIDM. Molecular ecology and adaptation of visual photopigments in craniates. Mol Ecol 2012; 21:3121-58. [DOI: 10.1111/j.1365-294x.2012.05617.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Carvalho LS, Davies WL, Robinson PR, Hunt DM. Spectral tuning and evolution of primate short-wavelength-sensitive visual pigments. Proc Biol Sci 2012; 279:387-93. [PMID: 21697177 PMCID: PMC3223675 DOI: 10.1098/rspb.2011.0782] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 06/02/2011] [Indexed: 11/12/2022] Open
Abstract
The peak sensitivities (λ(max)) of the short-wavelength-sensitive-1 (SWS1) pigments in mammals range from the ultraviolet (UV) (360-400 nm) to the violet (400-450 nm) regions of the spectrum. In most cases, a UV or violet peak is determined by the residue present at site 86, with Phe conferring UV sensitivity (UVS) and either Ser, Tyr or Val causing a shift to violet wavelengths. In primates, however, the tuning mechanism of violet-sensitive (VS) pigments would appear to differ. In this study, we examine the tuning mechanisms of prosimian SWS1 pigments. One species, the aye-aye, possesses a pigment with Phe86 but in vitro spectral analysis reveals a VS rather than a UVS pigment. Other residues (Cys, Ser and Val) at site 86 in prosimians also gave VS pigments. Substitution at site 86 is not, therefore, the primary mechanism for the tuning of VS pigments in primates, and phylogenetic analysis indicates that substitutions at site 86 have occurred at least five times in primate evolution. The sole potential tuning site that is conserved in all primate VS pigments is Pro93, which when substituted by Thr (as found in mammalian UVS pigments) in the aye-aye pigment shifted the peak absorbance into the UV region with a λ(max) value at 371 nm. We, therefore, conclude that the tuning of VS pigments in primates depends on Pro93, not Tyr86 as in other mammals. However, it remains uncertain whether the initial event that gave rise to the VS pigment in the ancestral primate was achieved by a Thr93Pro or a Phe86Tyr substitution.
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Affiliation(s)
| | - Wayne L. Davies
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | | | - David M. Hunt
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
- School of Animal Biology and Oceans Institute, University of Western Australia, Perth, WA 6009, Australia
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26
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Kuraku S, Meyer A. Detection and phylogenetic assessment of conserved synteny derived from whole genome duplications. Methods Mol Biol 2012; 855:385-95. [PMID: 22407717 DOI: 10.1007/978-1-61779-582-4_14] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Identification of intragenomic conservation of gene compositions in multiple chromosomal segments led to evidence of whole genome (WGDs) duplications. The process by which WGDs have been maintained and decayed provides us with clues for understanding how the genome evolves. In this chapter, we summarize current understanding of phylogenetic distribution and evolutionary impact of WGDs, introduce basic procedures to detect conserved synteny, and discuss typical pitfalls, as well as biological insights.
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Affiliation(s)
- Shigehiro Kuraku
- Genome Resource and Analysis Unit, RIKEN Center for Developmental Biology, Chuo-ku, Kobe, Japan.
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27
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Polymorphic Color Vision in Primates: Evolutionary Considerations. POST-GENOME BIOLOGY OF PRIMATES 2012. [DOI: 10.1007/978-4-431-54011-3_7] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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28
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Jacobs GH. The Evolution of Vertebrate Color Vision. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 739:156-72. [DOI: 10.1007/978-1-4614-1704-0_10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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29
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Kuraku S, Kuratani S. Genome-wide detection of gene extinction in early mammalian evolution. Genome Biol Evol 2011; 3:1449-62. [PMID: 22094861 PMCID: PMC3296468 DOI: 10.1093/gbe/evr120] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Detecting gene losses is a novel aspect of evolutionary genomics that has been made feasible by whole-genome sequencing. However, research to date has concentrated on elucidating evolutionary patterns of genomic components shared between species, rather than identifying disparities between genomes. In this study, we searched for gene losses in the lineage leading to eutherian mammals. First, as a pilot analysis, we selected five gene families (Wnt, Fgf, Tbx, TGFβ, and Frizzled) for molecular phylogenetic analyses, and identified mammalian lineage-specific losses of Wnt11b, Tbx6L/VegT/tbx16, Nodal-related, ADMP1, ADMP2, Sizzled, and Crescent. Second, automated genome-wide phylogenetic screening was implemented based on this pilot analysis. As a result, we detected 147 chicken genes without eutherian orthologs, which resulted from 141 gene loss events. Our inventory contained a group of regulatory genes governing early embryonic axis formation, such as Noggins, and multiple members of the opsin and prolactin-releasing hormone receptor (“PRLHR”) gene families. Our findings highlight the potential of genome-wide gene phylogeny (“phylome”) analysis in detecting possible rearrangement of gene networks and the importance of identifying losses of ancestral genomic components in analyzing the molecular basis underlying phenotypic evolution.
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Affiliation(s)
- Shigehiro Kuraku
- Laboratory for Evolutionary Morphology, RIKEN Center for Developmental Biology, Kobe, Japan.
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30
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Tam KJ, Watson CT, Massah S, Kolybaba AM, Breden F, Prefontaine GG, Beischlag TV. Regulatory function of conserved sequences upstream of the long-wave sensitive opsin genes in teleost fishes. Vision Res 2011; 51:2295-303. [PMID: 21971525 DOI: 10.1016/j.visres.2011.09.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/01/2011] [Accepted: 09/02/2011] [Indexed: 10/17/2022]
Abstract
Vertebrate opsin genes often occur in sets of tandem duplicates, and their expression varies developmentally and in response to environmental cues. We previously identified two highly conserved regions upstream of the long-wave sensitive opsin (LWS) gene cluster in teleosts. This region has since been shown in zebrafish to drive expression of LWS genes in vivo. In order to further investigate how elements in this region control opsin gene expression, we tested constructs encompassing the highly conserved regions and the less conserved portions upstream of the coding sequences in a promoter-less luciferase expression system. A ∼4500 bp construct of the upstream region, including the highly-conserved regions Reg I and Reg II, increased expression 100-fold, and successive 5' deletions reduced expression relative to the full 4.5 Kb region. Gene expression was highest when the transcription factor RORα was co-transfected with the proposed regulatory regions. Because these regions were tested in a promoter-less expression system, they include elements able to initiate and drive transcription. Teleosts exhibit complex color-mediated adaptive behavior and their adaptive significance has been well documented in several species. Therefore these upstream regions of LWS represent a model system for understanding the molecular basis of adaptive variation in gene regulation of color vision.
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Affiliation(s)
- Kevin J Tam
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada V5A 1S6
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31
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Zeiss CJ, Schwab IR, Murphy CJ, Dubielzig RW. Comparative retinal morphology of the platypus. J Morphol 2011; 272:949-57. [DOI: 10.1002/jmor.10959] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 12/30/2010] [Accepted: 02/26/2011] [Indexed: 01/03/2023]
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32
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Gutierrez EDA, Pegoraro BM, Magalhães-Castro B, Pessoa VF. Behavioural evidence of dichromacy in a species of South American marsupial. Anim Behav 2011. [DOI: 10.1016/j.anbehav.2011.02.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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33
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Mohun SM, Davies WL, Bowmaker JK, Pisani D, Himstedt W, Gower DJ, Hunt DM, Wilkinson M. Identification and characterization of visual pigments in caecilians (Amphibia: Gymnophiona), an order of limbless vertebrates with rudimentary eyes. ACTA ACUST UNITED AC 2011; 213:3586-92. [PMID: 20889838 DOI: 10.1242/jeb.045914] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In comparison with the other amphibian orders, the Anura (frogs) and Urodela (salamanders), knowledge of the visual system of the snake-like Gymnophiona (caecilians) is relatively sparse. Most caecilians are fossorial with, as far as is known any surface activity occurring mainly at night. They have relatively small, poorly developed eyes and might be expected to possess detectable changes in the spectral sensitivity of their visual pigments. Microspectrophotometry was used to determine the spectral sensitivities of the photoreceptors in three species of caecilian, Rhinatrema bivittatum, Geotrypetes seraphini and Typhlonectes natans. Only rod opsin visual pigment, which may be associated with scotopic (dim light) vision when accompanied by other 'rod-specific' components of the phototransduction cascade, was found to be present. Opsin sequences were obtained from the eyes of two species of caecilian, Ichthyophis cf. kohtaoensis and T. natans. These rod opsins were regenerated in vitro with 11-cis retinal to give pigments with spectral sensitivity peaks close to 500 nm. No evidence for cone photoreception, associated with diurnal and colour vision, was detected using molecular and physiological methods. Additionally, visual pigments are short-wavelength shifted in terms of the maximum absorption of light when compared with other amphibian lineages.
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Affiliation(s)
- S M Mohun
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V9EL, UK
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34
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Tsujimura T, Hosoya T, Kawamura S. A single enhancer regulating the differential expression of duplicated red-sensitive opsin genes in zebrafish. PLoS Genet 2010; 6:e1001245. [PMID: 21187910 PMCID: PMC3002997 DOI: 10.1371/journal.pgen.1001245] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 11/10/2010] [Indexed: 11/18/2022] Open
Abstract
A fundamental step in the evolution of the visual system is the gene duplication of visual opsins and differentiation between the duplicates in absorption spectra and expression pattern in the retina. However, our understanding of the mechanism of expression differentiation is far behind that of spectral tuning of opsins. Zebrafish (Danio rerio) have two red-sensitive cone opsin genes, LWS-1 and LWS-2. These genes are arrayed in a tail-to-head manner, in this order, and are both expressed in the long member of double cones (LDCs) in the retina. Expression of the longer-wave sensitive LWS-1 occurs later in development and is thus confined to the peripheral, especially ventral-nasal region of the adult retina, whereas expression of LWS-2 occurs earlier and is confined to the central region of the adult retina, shifted slightly to the dorsal-temporal region. In this study, we employed a transgenic reporter assay using fluorescent proteins and P1-artificial chromosome (PAC) clones encompassing the two genes and identified a 0.6-kb “LWS-activating region” (LAR) upstream of LWS-1, which regulates expression of both genes. Under the 2.6-kb flanking upstream region containing the LAR, the expression pattern of LWS-1 was recapitulated by the fluorescent reporter. On the other hand, when LAR was directly conjugated to the LWS-2 upstream region, the reporter was expressed in the LDCs but also across the entire outer nuclear layer. Deletion of LAR from the PAC clones drastically lowered the reporter expression of the two genes. These results suggest that LAR regulates both LWS-1 and LWS-2 by enhancing their expression and that interaction of LAR with the promoters is competitive between the two genes in a developmentally restricted manner. Sharing a regulatory region between duplicated genes could be a general way to facilitate the expression differentiation in duplicated visual opsins. Among vertebrates, fish may have the most advanced color vision. They have greatly varied repertoires of color sensors called visual opsins, possibly reflecting evolutionary adaptation to their diverse photic environments in water, and are an excellent model to study the evolution of vertebrate color vision. This is achieved by multiplying opsin genes and differentiating their absorption light spectra and expression patterns. However, little is understood regarding how the opsin genes are regulated to achieve the differential expression pattern. In this study, we focused on the duplicated red-sensitive opsin genes of zebrafish to tackle this problem. We discovered an “enhancer” region near the two red opsin genes that plays a crucial role in their differential expression pattern. Our results suggest that the two red opsin genes interact with the enhancer competitively in a developmentally restricted manner. Sharing a regulatory region could be a general way to facilitate the expression differentiation in duplicated visual opsin genes.
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Affiliation(s)
- Taro Tsujimura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan
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Ebeling W, Natoli RC, Hemmi JM. Diversity of color vision: not all Australian marsupials are trichromatic. PLoS One 2010; 5:e14231. [PMID: 21151905 PMCID: PMC2997786 DOI: 10.1371/journal.pone.0014231] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 11/01/2010] [Indexed: 11/25/2022] Open
Abstract
Color vision in marsupials has recently emerged as a particularly interesting case among mammals. It appears that there are both dichromats and trichromats among closely related species. In contrast to primates, marsupials seem to have evolved a different type of trichromacy that is not linked to the X-chromosome. Based on microspectrophotometry and retinal whole-mount immunohistochemistry, four trichromatic marsupial species have been described: quokka, quenda, honey possum, and fat-tailed dunnart. It has, however, been impossible to identify the photopigment of the third cone type, and genetically, all evidence so far suggests that all marsupials are dichromatic. The tammar wallaby is the only Australian marsupial to date for which there is no evidence of a third cone type. To clarify whether the wallaby is indeed a dichromat or trichromatic like other Australian marsupials, we analyzed the number of cone types in the “dichromatic” wallaby and the “trichromatic” dunnart. Employing identical immunohistochemical protocols, we confirmed that the wallaby has only two cone types, whereas 20–25% of cones remained unlabeled by S- and LM-opsin antibodies in the dunnart retina. In addition, we found no evidence to support the hypothesis that the rod photopigment (rod opsin) is expressed in cones which would have explained the absence of a third cone opsin gene. Our study is the first comprehensive and quantitative account of color vision in Australian marsupials where we now know that an unexpected diversity of different color vision systems appears to have evolved.
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Affiliation(s)
- Wiebke Ebeling
- ARC Centre of Excellence in Vision Science, Research School of Biology, ANU College of Medicine, Biology and Environment, The Australian National University, Canberra, Australia.
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Solovei I, Joffe B. Inverted nuclear architecture and its development during differentiation of mouse rod photoreceptor cells: A new model to study nuclear architecture. RUSS J GENET+ 2010. [DOI: 10.1134/s1022795410090024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Jacobs GH. The Verriest Lecture 2009: Recent progress in understanding mammalian color vision. Ophthalmic Physiol Opt 2010; 30:422-34. [DOI: 10.1111/j.1475-1313.2010.00719.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Palacios AG, Bozinovic F, Vielma A, Arrese CA, Hunt DM, Peichl L. Retinal photoreceptor arrangement, SWS1 and LWS opsin sequence, and electroretinography in the South American marsupial Thylamys elegans (Waterhouse, 1839). J Comp Neurol 2010; 518:1589-602. [PMID: 20187149 DOI: 10.1002/cne.22292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied the retinal photoreceptors in the mouse opossum Thylamys elegans, a nocturnal South American marsupial. A variety of photoreceptor properties and color vision capabilities have been documented in Australian marsupials, and we were interested to establish what similarities and differences this American marsupial showed. Thylamys opsin gene sequencing revealed two cone opsins, a longwave-sensitive (LWS) opsin and a shortwave-sensitive (SWS1) opsin with deduced peak sensitivities at 560 nm and 360 nm (ultraviolet), respectively. Immunocytochemistry located these opsins to separate cone populations, a majority of LWS cones (density range 1,600-5,600/mm(2)) and a minority of SWS1 cones (density range 100-690/mm(2)). With rod densities of 440,000-590,000/mm(2), the cones constituted 0.4-1.2% of the photoreceptors. This is a suitable adaptation to nocturnal vision. Cone densities peaked in a horizontally elongated region ventral to the optic nerve head. In ventral-but not dorsal-retina, roughly 40% of the LWS opsin-expressing cones occurred as close pairs (double cones), and one member of each double cone contained a colorless oil droplet. The corneal electroretinogram (ERG) showed a high scotopic sensitivity with a rod peak sensitivity at 505 nm. At mesopic light levels, the spectral ERG revealed the contributions of a UV-sensitive SWS1 cone mechanism and an LWS cone mechanism with peak sensitivities at 365 nm and 555 nm, respectively, confirming the tuning predictions from the cone opsin sequences. The two spectral cone types provide the basis for dichromatic color vision, or trichromacy if the rods contribute to color processing at mesopic light levels.
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Affiliation(s)
- Adrián G Palacios
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2370006, Chile
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Watson CT, Lubieniecki KP, Loew E, Davidson WS, Breden F. Genomic organization of duplicated short wave-sensitive and long wave-sensitive opsin genes in the green swordtail, Xiphophorus helleri. BMC Evol Biol 2010; 10:87. [PMID: 20353595 PMCID: PMC3087554 DOI: 10.1186/1471-2148-10-87] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Accepted: 03/30/2010] [Indexed: 01/10/2023] Open
Abstract
Background Long wave-sensitive (LWS) opsin genes have undergone multiple lineage-specific duplication events throughout the evolution of teleost fishes. LWS repertoire expansions in live-bearing fishes (family Poeciliidae) have equipped multiple species in this family with up to four LWS genes. Given that color vision, especially attraction to orange male coloration, is important to mate choice within poeciliids, LWS opsins have been proposed as candidate genes driving sexual selection in this family. To date the genomic organization of these genes has not been described in the family Poeciliidae, and little is known about the mechanisms regulating the expression of LWS opsins in any teleost. Results Two BAC clones containing the complete genomic repertoire of LWS opsin genes in the green swordtail fish, Xiphophorus helleri, were identified and sequenced. Three of the four LWS loci identified here were linked in a tandem array downstream of two tightly linked short wave-sensitive 2 (SWS2) opsin genes. The fourth LWS opsin gene, containing only a single intron, was not linked to the other three and is the product of a retrotransposition event. Genomic and phylogenetic results demonstrate that the LWS genes described here share a common evolutionary origin with those previously characterized in other poeciliids. Using qualitative RT-PCR and MSP we showed that each of the LWS and SWS2 opsins, as well as three other cone opsin genes and a single rod opsin gene, were expressed in the eyes of adult female and male X. helleri, contributing to six separate classes of adult retinal cone and rod cells with average λmax values of 365 nm, 405 nm, 459 nm, 499 nm, 534 nm and 568 nm. Comparative genomic analysis identified two candidate teleost opsin regulatory regions containing putative CRX binding sites and hormone response elements in upstream sequences of LWS gene regions of seven teleost species, including X. helleri. Conclusions We report the first complete genomic description of LWS and SWS2 genes in poeciliids. These data will serve as a reference for future work seeking to understand the relationship between LWS opsin genomic organization, gene expression, gene family evolution, sexual selection and speciation in this fish family.
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Affiliation(s)
- Corey T Watson
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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Jacobs GH, Williams GA. Cone pigments in a North American marsupial, the opossum (Didelphis virginiana). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:379-84. [PMID: 20224889 PMCID: PMC2858275 DOI: 10.1007/s00359-010-0519-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 02/26/2010] [Accepted: 03/02/2010] [Indexed: 11/16/2022]
Abstract
Only two of the four cone opsin gene families found in vertebrates are represented in contemporary eutherian and marsupial species. Recent genetic studies of two species of South American marsupial detected the presence of representatives from two of the classes of cone opsin genes and the structures of these genes predicted cone pigments with respective peaks in the ultraviolet and long-wavelength portions of the spectrum. The Virginia opossum (Didelphis virginiana), a profoundly nocturnal animal, is the only marsupial species found in North America. The prospects for cone-based vision in this species were examined through recordings of the electroretinogram (ERG), a commonly examined retinal response to photic stimulation. Recorded under flickering-light conditions that elicit signals from cone photoreceptors, the spectral sensitivity of the opossum eye is well accounted for by contributions from the presence of a single cone pigment having peak absorption at 561–562 nm. A series of additional experiments that employed various chromatic adaptation paradigms were conducted in a search for possible contributions from a second (short-wavelength sensitive) cone pigment. We found no evidence that such a mechanism contributes to the ERG in this marsupial.
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Affiliation(s)
- Gerald H Jacobs
- Department of Psychology, University of California, Santa Barbara, 93106, USA.
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Hunt DM, Carvalho LS, Cowing JA, Davies WL. Evolution and spectral tuning of visual pigments in birds and mammals. Philos Trans R Soc Lond B Biol Sci 2009; 364:2941-55. [PMID: 19720655 DOI: 10.1098/rstb.2009.0044] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Variation in the types and spectral characteristics of visual pigments is a common mechanism for the adaptation of the vertebrate visual system to prevailing light conditions. The extent of this diversity in mammals and birds is discussed in detail in this review, alongside an in-depth consideration of the molecular changes involved. In mammals, a nocturnal stage in early evolution is thought to underlie the reduction in the number of classes of cone visual pigment genes from four to only two, with the secondary loss of one of these genes in many monochromatic nocturnal and marine species. The trichromacy seen in many primates arises from either a polymorphism or duplication of one of these genes. In contrast, birds have retained the four ancestral cone visual pigment genes, with a generally conserved expression in either single or double cone classes. The loss of sensitivity to ultraviolet (UV) irradiation is a feature of both mammalian and avian visual evolution, with UV sensitivity retained among mammals by only a subset of rodents and marsupials. Where it is found in birds, it is not ancestral but newly acquired.
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Affiliation(s)
- David M Hunt
- UCL Institute of Ophthalmology, London EC1V 9EL, UK.
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Abstract
Colour vision allows animals to reliably distinguish differences in the distributions of spectral energies reaching the eye. Although not universal, a capacity for colour vision is sufficiently widespread across the animal kingdom to provide prima facie evidence of its importance as a tool for analysing and interpreting the visual environment. The basic biological mechanisms on which vertebrate colour vision ultimately rests, the cone opsin genes and the photopigments they specify, are highly conserved. Within that constraint, however, the utilization of these basic elements varies in striking ways in that they appear, disappear and emerge in altered form during the course of evolution. These changes, along with other alterations in the visual system, have led to profound variations in the nature and salience of colour vision among the vertebrates. This article concerns the evolution of colour vision among the mammals, viewing that process in the context of relevant biological mechanisms, of variations in mammalian colour vision, and of the utility of colour vision.
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Affiliation(s)
- Gerald H Jacobs
- Neuroscience Research Institute and Department of Psychology, University of California, Santa Barbara, CA 93106, USA.
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Hofmann CM, Carleton KL. Gene duplication and differential gene expression play an important role in the diversification of visual pigments in fish. Integr Comp Biol 2009; 49:630-43. [DOI: 10.1093/icb/icp079] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Abstract
Thirty years ago virtually everything known about primate color vision derived from psychophysical studies of normal and color-defective humans and from physiological investigations of the visual system of the macaque monkey, the most popular of human surrogates for this purpose. The years since have witnessed much progress toward the goal of understanding this remarkable feature of primate vision. Among many advances, investigations focused on naturally occurring variations in color vision in a wide range of nonhuman primate species have proven to be particularly valuable. Results from such studies have been central to our expanding understanding of the interrelationships between opsin genes, cone photopigments, neural organization, and color vision. This work is also yielding valuable insights into the evolution of color vision.
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Cone visual pigments in two species of South American marsupials. Gene 2008; 433:50-5. [PMID: 19133321 DOI: 10.1016/j.gene.2008.12.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/03/2008] [Accepted: 12/05/2008] [Indexed: 11/22/2022]
Abstract
Marsupials are largely confined to Australasia and to Central and South America. The visual pigments that underlie the photosensitivity of the retina have been examined in a number of species from the former group where evidence for trichromatic colour vision has been found, but none from the latter. In this paper, we report the cone opsin sequences from two nocturnal South American marsupial species, the gray short-tailed opossum, Monodelphis domestica, and the big-eared opossum, Didelphis aurita. Both are members of the Order Didelphimorphia (American opossums). For both species, only two classes of cone opsin were found, an SWS1 and an LWS sequence, and in vitro expression showed that the peak sensitivity of the SWS1 pigment is in the UV. Analysis of the Monodelphis genome confirms the absence of other classes of cone visual pigment genes. The SWS1 and LWS genes with 4 and 5 introns respectively, show the same exon-intron structure as found for these genes in all other vertebrates. The SWS1 gene shows a conserved synteny with flanking genes. The LWS gene is X-linked, as in all therian mammals so far examined, with a locus control region 1.54 kb upstream.
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Takechi M, Seno S, Kawamura S. Identification of cis-acting elements repressing blue opsin expression in zebrafish UV cones and pineal cells. J Biol Chem 2008; 283:31625-32. [PMID: 18796431 DOI: 10.1074/jbc.m806226200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Opsin genes are expressed in a cell type-specific manner in the retina and the pineal organ for visual and nonvisual photoreceptive purposes, but the regulatory mechanism behind the tissue and cell selectivity is not well understood. In this study, we focus on the expression regulation of the blue-sensitive opsin gene SWS2 of zebrafish by taking a transgenic approach using the green fluorescence protein as an expression reporter. The zebrafish SWS2 is a single-copy gene and is expressed specifically in the "long single cones" in the retina. We found the following. 1) A 0.3-kb region between 0.6 and 0.3 kb 5' of the SWS2 initiation codon, encompassing four cone-rod homeobox-binding sites (OTX sequences), contains the region necessary and sufficient to drive gene expression in long single cones. 2) A 15-bp portion (-341 to -327) in the 0.3-kb region represses the gene expression in the "short single cones," which are dedicated to the UV-sensitive opsin gene SWS1. 3) An 11-bp sequence TAACTGCCAGT (-441 to -431) in the 0.3-kb region, with its adjacent OTX element, also works as a repressor for gene expression in the pineal cells. 4) Finally, this OTX site is necessary for expression repression in the bipolar cells in the retina. These findings open a way for understanding the complex interaction of positive and negative regulatory factors that govern the cell type specificity of the opsin gene expression in the photoreceptive cells in the retina and the pineal organ. We termed the novel 11-bp sequence as the pineal negative regulatory element, PINE.
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Affiliation(s)
- Masaki Takechi
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, the University of Tokyo, Kashiwa, Chiba 277-8562, Japan
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Cowing JA, Arrese CA, Davies WL, Beazley LD, Hunt DM. Cone visual pigments in two marsupial species: the fat-tailed dunnart (Sminthopsis crassicaudata) and the honey possum (Tarsipes rostratus). Proc Biol Sci 2008; 275:1491-9. [PMID: 18426754 DOI: 10.1098/rspb.2008.0248] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Uniquely for non-primate mammals, three classes of cone photoreceptors have been previously identified by microspectrophotometry in two marsupial species: the polyprotodont fat-tailed dunnart (Sminthopsis crassicaudata) and the diprotodont honey possum (Tarsipes rostratus). This report focuses on the genetic basis for these three pigments. Two cone pigments were amplified from retinal cDNA of both species and identified by phylogenetics as members of the short wavelength-sensitive 1 (SWS1) and long wavelength-sensitive (LWS) opsin classes. In vitro expression of the two sequences from the fat-tailed dunnart confirmed the peak absorbances at 363 nm in the UV for the SWS1 pigment and 533 nm for the LWS pigment. No additional expressed cone opsin sequences that could account for the middle wavelength cones could be amplified. However, amplification from the fat-tailed dunnart genomic DNA with RH1 (rod) opsin primer pairs identified two genes with identical coding regions but sequence differences in introns 2 and 3. Uniquely therefore for a mammal, the fat-tailed dunnart has two copies of an RH1 opsin gene. This raises the possibility that the middle wavelength cones express a rod rather than a cone pigment.
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Affiliation(s)
- Jill A Cowing
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
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Bowmaker JK. Evolution of vertebrate visual pigments. Vision Res 2008; 48:2022-41. [PMID: 18590925 DOI: 10.1016/j.visres.2008.03.025] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 03/14/2008] [Accepted: 03/18/2008] [Indexed: 10/21/2022]
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