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Feuda R, Goulty M, Zadra N, Gasparetti T, Rosato E, Pisani D, Rizzoli A, Segata N, Ometto L, Stabelli OR. Phylogenomics of Opsin Genes in Diptera Reveals Lineage-Specific Events and Contrasting Evolutionary Dynamics in Anopheles and Drosophila. Genome Biol Evol 2021; 13:6322995. [PMID: 34270718 PMCID: PMC8369074 DOI: 10.1093/gbe/evab170] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2021] [Indexed: 12/12/2022] Open
Abstract
Diptera is one of the biggest insect orders and displays a large diversity of visual adaptations. Similarly to other animals, the dipteran visual process is mediated by opsin genes. Although the diversity and function of these genes are well studied in key model species, a comprehensive comparative genomic study across the dipteran phylogeny is missing. Here we mined the genomes of 61 dipteran species, reconstructed the evolutionary affinities of 528 opsin genes, and determined the selective pressure acting in different species. We found that opsins underwent several lineage-specific events, including an independent expansion of Long Wave Sensitive opsins in flies and mosquitoes, and numerous family-specific duplications and losses. Both the Drosophila and the Anopheles complement are derived in comparison with the ancestral dipteran state. Molecular evolutionary studies suggest that gene turnover rate, overall mutation rate, and site-specific selective pressure are higher in Anopheles than in Drosophila. Overall, our findings indicate an extremely variable pattern of opsin evolution in dipterans, showcasing how two similarly aged radiations, Anopheles and Drosophila, are characterized by contrasting dynamics in the evolution of this gene family. These results provide a foundation for future studies on the dipteran visual system.
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Affiliation(s)
- Roberto Feuda
- Department of Genetics and Genome Biology, University of Leicester, UK.,Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Matthew Goulty
- Department of Genetics and Genome Biology, University of Leicester, UK
| | - Nicola Zadra
- Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all'Adige, Italy.,Department CIBIO, University of Trento, Italy
| | | | - Ezio Rosato
- Department of Genetics and Genome Biology, University of Leicester, UK
| | | | - Annapaola Rizzoli
- Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all'Adige, Italy
| | | | - Lino Ometto
- Department of Biology and Biotechnology, University of Pavia, Italy
| | - Omar Rota Stabelli
- Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all'Adige, Italy.,Center Agriculture Food Environment (C3A), University of Trento, Italy
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Wu M, Bao R, Friedrich M. Evolutionary conservation of opsin gene expression patterns in the compound eyes of darkling beetles. Dev Genes Evol 2020; 230:339-345. [DOI: 10.1007/s00427-020-00669-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 09/21/2020] [Indexed: 01/07/2023]
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Bian L, Cai XM, Luo ZX, Li ZQ, Chen ZM. Foliage Intensity is an Important Cue of Habitat Location for Empoasca onukii. INSECTS 2020; 11:insects11070426. [PMID: 32659987 PMCID: PMC7412280 DOI: 10.3390/insects11070426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 11/02/2022]
Abstract
For many herbivorous insects, vision is more important than olfaction in the prealighting stage of host habitat location. Tea leafhoppers, Empoasca onukii (Hemiptera, Cicadellidae), are serious pests that preferentially inhabit the tender leaves of tea plants across China. Here, we investigated whether tea leafhoppers could distinguish foliage colors associated with different leaf ages and use this visual cue to guide suitable habitat location from short distances. Similar to honeybees, the adult E. onukii has an apposition type of compound eye, and each ommatidium has eight retinular cells, in which three spectral types of photoreceptors are distributed, with peak sensitivities at 356 nm (ultraviolet), 435 nm (blue), and 542 nm (green). Both changes in spectral intensity and hue of reflectance light of the host foliage were correlated with varying leaf age, and the intensity linearly decreased with increasing leaf age. Behavioral responses also showed that adult E. onukii could discriminate between the simulated colors of host foliage at different leaf ages without olfactory stimuli and selected the bright colors that strongly corresponded to those of tender leaves. The results suggest that, compared with the spectral composition (hue), the intensity of light reflectance from leaves at different ages is more important for adult leafhoppers when discriminating host foliage and could guide them to tender leaves at the top of tea shoots.
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Affiliation(s)
- Lei Bian
- Tea Research Institute, Chinese Academy of Agricultural Science, 9 Meiling South Road, Xihu District, Hangzhou 310008, China; (L.B.); (X.M.C.); (Z.X.L.); (Z.Q.L.)
- Key Laboratory of Tea Biology and Resource Utilization, Ministry of Agriculture, 9 Meiling South Road, Xihu District, Hangzhou 310008, China
| | - Xiao Ming Cai
- Tea Research Institute, Chinese Academy of Agricultural Science, 9 Meiling South Road, Xihu District, Hangzhou 310008, China; (L.B.); (X.M.C.); (Z.X.L.); (Z.Q.L.)
- Key Laboratory of Tea Biology and Resource Utilization, Ministry of Agriculture, 9 Meiling South Road, Xihu District, Hangzhou 310008, China
| | - Zong Xiu Luo
- Tea Research Institute, Chinese Academy of Agricultural Science, 9 Meiling South Road, Xihu District, Hangzhou 310008, China; (L.B.); (X.M.C.); (Z.X.L.); (Z.Q.L.)
- Key Laboratory of Tea Biology and Resource Utilization, Ministry of Agriculture, 9 Meiling South Road, Xihu District, Hangzhou 310008, China
| | - Zhao Qun Li
- Tea Research Institute, Chinese Academy of Agricultural Science, 9 Meiling South Road, Xihu District, Hangzhou 310008, China; (L.B.); (X.M.C.); (Z.X.L.); (Z.Q.L.)
- Key Laboratory of Tea Biology and Resource Utilization, Ministry of Agriculture, 9 Meiling South Road, Xihu District, Hangzhou 310008, China
| | - Zong Mao Chen
- Tea Research Institute, Chinese Academy of Agricultural Science, 9 Meiling South Road, Xihu District, Hangzhou 310008, China; (L.B.); (X.M.C.); (Z.X.L.); (Z.Q.L.)
- Key Laboratory of Tea Biology and Resource Utilization, Ministry of Agriculture, 9 Meiling South Road, Xihu District, Hangzhou 310008, China
- Correspondence: ; Tel.: +86-571-86650100
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Electrophysiological adaptations of insect photoreceptors and their elementary responses to diurnal and nocturnal lifestyles. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:55-69. [PMID: 31858215 PMCID: PMC6995784 DOI: 10.1007/s00359-019-01392-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/18/2019] [Accepted: 12/03/2019] [Indexed: 12/16/2022]
Abstract
Nocturnal vision in insects depends on the ability to reliably detect scarce photons. Nocturnal insects tend to have intrinsically more sensitive and larger rhabdomeres than diurnal species. However, large rhabdomeres have relatively high membrane capacitance (Cm), which can strongly low-pass filter the voltage bumps, widening and attenuating them. To investigate the evolution of photoreceptor signaling under near dark, we recorded elementary current and voltage responses from a number of species in six insect orders. We found that the gain of phototransduction increased with Cm, so that nocturnal species had relatively large and prolonged current bumps. Consequently, although the voltage bump amplitude correlated negatively with Cm, the strength of the total voltage signal increased. Importantly, the background voltage noise decreased strongly with increasing Cm, yielding a notable increase in signal-to-noise ratio for voltage bumps. A similar decrease in the background noise with increasing Cm was found in intracellular recordings in vivo. Morphological measurements of rhabdomeres were consistent with our Cm estimates. Our results indicate that the increased photoreceptor Cm in nocturnal insects is a major sensitivity-boosting and noise-suppressing adaptation. However, by requiring a compensatory increase in the gain of phototransduction, this adaptation comes at the expense of the signaling bandwidth.
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Photoreceptor spectral tuning by colorful, multilayered facet lenses in long-legged fly eyes (Dolichopodidae). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 203:23-33. [PMID: 27873005 PMCID: PMC5263225 DOI: 10.1007/s00359-016-1131-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/05/2016] [Accepted: 11/08/2016] [Indexed: 11/27/2022]
Abstract
The facet lenses of the compound eyes of long-legged flies (Dolichopodidae) feature a striking, interlaced coloration pattern, existing of alternating rows of green-yellow and orange-red reflecting facets, due to dielectric multilayers located distally in the facet lenses (Bernard and Miller. Invest Ophthalmol 7:416–434 (1968). We investigated this phenomenon in the dolichopodid Dolichopus nitidus by applying microspectrophotometry, electron microscopy and optical modeling. The measured narrow-band reflectance spectra, peaking at ~540 and ~590 nm with bandwidth ~105 nm, are well explained by a refractive index oscillating sinusoidally in six periods around a mean value of about 1.44 with amplitude 0.6. The facet lens reflectance spectra are associated with a spectrally restricted, reduced transmittance, which causes modified spectral sensitivities of the underlying photoreceptors. Based on the modeling and electroretinography of the dolichopodid Condylostylus japonicus we conjecture that the green and orange facets narrow the spectral bandwidths of blue and green central photoreceptors, respectively, thus possibly improving color and/or polarization vision.
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Anstead CA, Batterham P, Korhonen PK, Young ND, Hall RS, Bowles VM, Richards S, Scott MJ, Gasser RB. A blow to the fly — Lucilia cuprina draft genome and transcriptome to support advances in biology and biotechnology. Biotechnol Adv 2016; 34:605-620. [DOI: 10.1016/j.biotechadv.2016.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 02/08/2016] [Accepted: 02/20/2016] [Indexed: 02/07/2023]
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Wernet MF, Perry MW, Desplan C. The evolutionary diversity of insect retinal mosaics: common design principles and emerging molecular logic. Trends Genet 2015; 31:316-28. [PMID: 26025917 PMCID: PMC4458154 DOI: 10.1016/j.tig.2015.04.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 04/13/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022]
Abstract
Independent evolution has resulted in a vast diversity of eyes. Despite the lack of a common Bauplan or ancestral structure, similar developmental strategies are used. For instance, different classes of photoreceptor cells (PRs) are distributed stochastically and/or localized in different regions of the retina. Here, we focus on recent progress made towards understanding the molecular principles behind patterning retinal mosaics of insects, one of the most diverse groups of animals adapted to life on land, in the air, under water, or on the water surface. Morphological, physiological, and behavioral studies from many species provide detailed descriptions of the vast variation in retinal design and function. By integrating this knowledge with recent progress in the characterization of insect Rhodopsins as well as insight from the model organism Drosophila melanogaster, we seek to identify the molecular logic behind the adaptation of retinal mosaics to the habitat and way of life of an animal.
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Affiliation(s)
- Mathias F Wernet
- New York University Abu Dhabi, Abu Dhabi, 129188 Saadiyat Island, United Arab Emirates
| | - Michael W Perry
- Department of Biology, New York University, New York, NY 10003, USA
| | - Claude Desplan
- New York University Abu Dhabi, Abu Dhabi, 129188 Saadiyat Island, United Arab Emirates; Department of Biology, New York University, New York, NY 10003, USA.
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Abstract
Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein-encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology.
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Posnien N, Hopfen C, Hilbrant M, Ramos-Womack M, Murat S, Schönauer A, Herbert SL, Nunes MDS, Arif S, Breuker CJ, Schlötterer C, Mitteroecker P, McGregor AP. Evolution of eye morphology and rhodopsin expression in the Drosophila melanogaster species subgroup. PLoS One 2012; 7:e37346. [PMID: 22662147 PMCID: PMC3360684 DOI: 10.1371/journal.pone.0037346] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 04/18/2012] [Indexed: 01/31/2023] Open
Abstract
A striking diversity of compound eye size and shape has evolved among insects. The number of ommatidia and their size are major determinants of the visual sensitivity and acuity of the compound eye. Each ommatidium is composed of eight photoreceptor cells that facilitate the discrimination of different colours via the expression of various light sensitive Rhodopsin proteins. It follows that variation in eye size, shape, and opsin composition is likely to directly influence vision. We analyzed variation in these three traits in D. melanogaster, D. simulans and D. mauritiana. We show that D. mauritiana generally has larger eyes than its sibling species, which is due to a combination of larger ommatidia and more ommatidia. In addition, intra- and inter-specific differences in eye size among D. simulans and D. melanogaster strains are mainly caused by variation in ommatidia number. By applying a geometric morphometrics approach to assess whether the formation of larger eyes influences other parts of the head capsule, we found that an increase in eye size is associated with a reduction in the adjacent face cuticle. Our shape analysis also demonstrates that D. mauritiana eyes are specifically enlarged in the dorsal region. Intriguingly, this dorsal enlargement is associated with enhanced expression of rhodopsin 3 in D. mauritiana. In summary, our data suggests that the morphology and functional properties of the compound eyes vary considerably within and among these closely related Drosophila species and may be part of coordinated morphological changes affecting the head capsule.
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Affiliation(s)
- Nico Posnien
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Corinna Hopfen
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Maarten Hilbrant
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Margarita Ramos-Womack
- Howard Hughes Medical Institute, Princeton University, Princeton, New Jersey, United States of America
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Sophie Murat
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Anna Schönauer
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Samantha L. Herbert
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal
| | - Maria D. S. Nunes
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Saad Arif
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Casper J. Breuker
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
| | - Christian Schlötterer
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
| | - Philipp Mitteroecker
- Department of Theoretical Biology, University of Vienna, Vienna, Austria
- * E-mail: (PM); or (APM)
| | - Alistair P. McGregor
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, United Kingdom
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
- * E-mail: (PM); or (APM)
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Rister J, Desplan C. The retinal mosaics of opsin expression in invertebrates and vertebrates. Dev Neurobiol 2012; 71:1212-26. [PMID: 21557510 DOI: 10.1002/dneu.20905] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Color vision is found in many invertebrate and vertebrate species. It is the ability to discriminate objects based on the wavelength of emitted light independent of intensity. As it requires the comparison of at least two photoreceptor types with different spectral sensitivities, this process is often mediated by a mosaic made of several photoreceptor types. In this review, we summarize the current knowledge about the formation of retinal mosaics and the regulation of photopigment (opsin) expression in the fly, mouse, and human retina. Despite distinct evolutionary origins, as well as major differences in morphology and phototransduction machineries, there are significant similarities in the stepwise cell-fate decisions that lead from progenitor cells to terminally differentiated photoreceptors that express a particular opsin. Common themes include (i) the use of binary transcriptional switches that distinguish classes of photoreceptors, (ii) the use of gradients of signaling molecules for regional specializations, (iii) stochastic choices that pattern the retina, and (iv) the use of permissive factors with multiple roles in different photoreceptor types.
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Affiliation(s)
- Jens Rister
- Department of Biology, Center for Developmental Genetics, New York University, USA
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Barsanti L, Evangelista V, Passarelli V, Frassanito AM, Gualtieri P. Fundamental questions and concepts about photoreception and the case of Euglena gracilis. Integr Biol (Camb) 2011; 4:22-36. [PMID: 22081035 DOI: 10.1039/c1ib00115a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The ability to sense light can be considered the most fundamental and presumably the most ancient property of visual systems. This ability is the basis of phototaxis, one of the most striking behavioral responses of motile photosynthetic microorganisms (i.e. microalgae) to light stimuli, which allows them to move toward or away directional light. In order to fully exploit the information content of light (intensity, direction, distribution) microorganisms need proper perceiving devices, termed photoreceptors, which must act as sensors, to perceive wavelength and direction of light, as transducers, to convert the light signal into chemical and/or electrical information, but also as amplifiers and eventually as transmitters. This review describes the universal structural, behavioral and physiological features necessary for the proper functioning of these devices in algae, and how these features have been investigated by means of different analytical techniques such as for example microspectroscopy, digital fluorescence microscopy, two photons FLIM. The insight of the photoreceptive response mechanism is explained using the unicellular alga Euglena gracilis, in which the different structural, behavioral and physiological features combine to achieve a concerted, efficient response to light stimuli.
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Affiliation(s)
- Laura Barsanti
- Istituto di Biofisica, CNR, via Moruzzi 1, 56124 Pisa, Italy
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Friedrich M, Wood EJ, Wu M. Developmental evolution of the insect retina: insights from standardized numbering of homologous photoreceptors. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2011; 316:484-99. [DOI: 10.1002/jez.b.21424] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 05/26/2011] [Indexed: 11/09/2022]
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Barsanti L, Coltelli P, Evangelista V, Passarelli V, Frassanito AM, Vesentini N, Santoro F, Gualtieri P. In VivoAbsorption Spectra of the Two Stable States of theEuglenaPhotoreceptor Photocycle. Photochem Photobiol 2009; 85:304-12. [DOI: 10.1111/j.1751-1097.2008.00438.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wernet MF, Mazzoni EO, Çelik A, Duncan DM, Duncan I, Desplan C. Stochastic spineless expression creates the retinal mosaic for colour vision. Nature 2006; 440:174-80. [PMID: 16525464 PMCID: PMC3826883 DOI: 10.1038/nature04615] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2005] [Accepted: 01/30/2006] [Indexed: 11/10/2022]
Abstract
Drosophila colour vision is achieved by R7 and R8 photoreceptor cells present in every ommatidium. The fly retina contains two types of ommatidia, called 'pale' and 'yellow', defined by different rhodopsin pairs expressed in R7 and R8 cells. Similar to the human cone photoreceptors, these ommatidial subtypes are distributed stochastically in the retina. The choice between pale versus yellow ommatidia is made in R7 cells, which then impose their fate onto R8. Here we report that the Drosophila dioxin receptor Spineless is both necessary and sufficient for the formation of the ommatidial mosaic. A short burst of spineless expression at mid-pupation in a large subset of R7 cells precedes rhodopsin expression. In spineless mutants, all R7 and most R8 cells adopt the pale fate, whereas overexpression of spineless is sufficient to induce the yellow R7 fate. Therefore, this study suggests that the entire retinal mosaic required for colour vision is defined by the stochastic expression of a single transcription factor, Spineless.
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Affiliation(s)
- Mathias F Wernet
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Place, New York, New York 10003, USA
| | - Esteban O Mazzoni
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Place, New York, New York 10003, USA
| | - Arzu Çelik
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Place, New York, New York 10003, USA
| | - Dianne M Duncan
- Department of Biology, Washington University, Box 1229, 1 Brookings Drive, St Louis, Missouri 63130, USA
| | - Ian Duncan
- Department of Biology, Washington University, Box 1229, 1 Brookings Drive, St Louis, Missouri 63130, USA
| | - Claude Desplan
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Place, New York, New York 10003, USA
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Takemura SY, Arikawa K. Ommatidial type-specific interphotoreceptor connections in the lamina of the swallowtail butterfly, Papilio xuthus. J Comp Neurol 2006; 494:663-72. [PMID: 16374804 DOI: 10.1002/cne.20830] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The eye of the butterfly Papilio xuthus contains a random array of three types of ommatidia (types I-III), each bearing nine photoreceptors, R1-R9. Of the six spectral classes of photoreceptors identified, types I, II, and III ommatidia contain four, three, and two classes, respectively: the ommatidia are thus spectrally heterogeneous. The photoreceptors send their axons to the lamina where, together with some large monopolar cells (LMCs), the nine from a single ommatidium contribute to a module called a lamina cartridge. We recently reported that among different photoreceptor axon terminals visualized by confocal microscopy, the number and length of axon collaterals differ for different spectral receptors, suggesting that lamina circuits are specific for each ommatidial type. Here we studied the distribution of synapse-like structures in the cartridges, first characterizing a photoreceptor by measuring its spectral sensitivity and then injecting Lucifer yellow (LY). We subsequently histologically identified the type of ommatidium to which the injected photoreceptor belonged, cut serial ultrathin sections of the entire lamina, labeled these with anti-LY immunocytochemistry, and then localized synapse-like structures. We found numerous interphotoreceptor contacts both within and between cartridges, the combination of which was again specific for the ommatidial type. R3 and R4, which are green-sensitive photoreceptors in all ommatidia, have thick axons lacking collaterals. We found that these cells exclusively make contacts with LMCs and not with photoreceptors. We therefore presume that R3 and R4 construct a system for motion vision, whereas other randomly distributed spectral types provide inputs for color vision.
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Affiliation(s)
- Shin-Ya Takemura
- Graduate School of Integrated Science, Yokohama City University, Yokohama 236-0027, Japan
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