1
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Stein WD. Orthologs at the Base of the Olfactores Clade. Genes (Basel) 2024; 15:657. [PMID: 38927593 PMCID: PMC11203038 DOI: 10.3390/genes15060657] [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: 04/12/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 06/28/2024] Open
Abstract
Tunicate orthologs in the human genome comprise just 84 genes of the 19,872 protein-coding genes and 23 of the 16,528 non-coding genes, yet they stand at the base of the Olfactores clade, which radiated to generate thousands of tunicate and vertebrate species. What were the powerful drivers among these genes that enabled this process? Many of these orthologs are present in gene families. We discuss the biological role of each family and the orthologs' quantitative contribution to the family. Most important was the evolution of a second type of cadherin. This, a Type II cadherin, had the property of detaching the cell containing that cadherin from cells that expressed the Type I class. The set of such Type II cadherins could now detach and move away from their Type I neighbours, a process which would eventually evolve into the formation of the neural crest, "the fourth germ layer", providing a wide range of possibilities for further evolutionary invention. A second important contribution were key additions to the broad development of the muscle and nerve protein and visual perception toolkits. These developments in mobility and vision provided the basis for the development of the efficient predatory capabilities of the Vertebrata.
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Affiliation(s)
- Wilfred D Stein
- Silberman Institute of Life Sciences, Hebrew University, Jerusalem 91904, Israel
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2
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Rosner A, Ballarin L, Barnay-Verdier S, Borisenko I, Drago L, Drobne D, Concetta Eliso M, Harbuzov Z, Grimaldi A, Guy-Haim T, Karahan A, Lynch I, Giulia Lionetto M, Martinez P, Mehennaoui K, Oruc Ozcan E, Pinsino A, Paz G, Rinkevich B, Spagnuolo A, Sugni M, Cambier S. A broad-taxa approach as an important concept in ecotoxicological studies and pollution monitoring. Biol Rev Camb Philos Soc 2024; 99:131-176. [PMID: 37698089 DOI: 10.1111/brv.13015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/13/2023]
Abstract
Aquatic invertebrates play a pivotal role in (eco)toxicological assessments because they offer ethical, cost-effective and repeatable testing options. Additionally, their significance in the food chain and their ability to represent diverse aquatic ecosystems make them valuable subjects for (eco)toxicological studies. To ensure consistency and comparability across studies, international (eco)toxicology guidelines have been used to establish standardised methods and protocols for data collection, analysis and interpretation. However, the current standardised protocols primarily focus on a limited number of aquatic invertebrate species, mainly from Arthropoda, Mollusca and Annelida. These protocols are suitable for basic toxicity screening, effectively assessing the immediate and severe effects of toxic substances on organisms. For more comprehensive and ecologically relevant assessments, particularly those addressing long-term effects and ecosystem-wide impacts, we recommended the use of a broader diversity of species, since the present choice of taxa exacerbates the limited scope of basic ecotoxicological studies. This review provides a comprehensive overview of (eco)toxicological studies, focusing on major aquatic invertebrate taxa and how they are used to assess the impact of chemicals in diverse aquatic environments. The present work supports the use of a broad-taxa approach in basic environmental assessments, as it better represents the natural populations inhabiting various ecosystems. Advances in omics and other biochemical and computational techniques make the broad-taxa approach more feasible, enabling mechanistic studies on non-model organisms. By combining these approaches with in vitro techniques together with the broad-taxa approach, researchers can gain insights into less-explored impacts of pollution, such as changes in population diversity, the development of tolerance and transgenerational inheritance of pollution responses, the impact on organism phenotypic plasticity, biological invasion outcomes, social behaviour changes, metabolome changes, regeneration phenomena, disease susceptibility and tissue pathologies. This review also emphasises the need for harmonised data-reporting standards and minimum annotation checklists to ensure that research results are findable, accessible, interoperable and reusable (FAIR), maximising the use and reusability of data. The ultimate goal is to encourage integrated and holistic problem-focused collaboration between diverse scientific disciplines, international standardisation organisations and decision-making bodies, with a focus on transdisciplinary knowledge co-production for the One-Health approach.
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Affiliation(s)
- Amalia Rosner
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO 2336 Sha'ar Palmer 1, Haifa, 3102201, Israel
| | - Loriano Ballarin
- Department of Biology, University of Padova, via Ugo Bassi 58/B, Padova, I-35121, Italy
| | - Stéphanie Barnay-Verdier
- Sorbonne Université; CNRS, INSERM, Université Côte d'Azur, Institute for Research on Cancer and Aging Nice, 28 avenue Valombrose, Nice, F-06107, France
| | - Ilya Borisenko
- Faculty of Biology, Department of Embryology, Saint Petersburg State University, Universitetskaya embankment 7/9, Saint Petersburg, 199034, Russia
| | - Laura Drago
- Department of Biology, University of Padova, via Ugo Bassi 58/B, Padova, I-35121, Italy
| | - Damjana Drobne
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, Ljubljana, 1111, Slovenia
| | - Maria Concetta Eliso
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, 80121, Italy
- Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy
| | - Zoya Harbuzov
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO 2336 Sha'ar Palmer 1, Haifa, 3102201, Israel
- Leon H. Charney School of Marine Sciences, Department of Marine Biology, University of Haifa, 199 Aba Koushy Ave., Haifa, 3498838, Israel
| | - Annalisa Grimaldi
- Department of Biotechnology and Life Sciences, University of Insubria, Via J. H. Dunant, Varese, 3-21100, Italy
| | - Tamar Guy-Haim
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO 2336 Sha'ar Palmer 1, Haifa, 3102201, Israel
| | - Arzu Karahan
- Middle East Technical University, Institute of Marine Sciences, Erdemli-Mersin, PO 28, 33731, Turkey
| | - Iseult Lynch
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Maria Giulia Lionetto
- Department of Biological and Environmental Sciences and Technologies, University of Salento, via prov. le Lecce -Monteroni, Lecce, I-73100, Italy
- NBFC, National Biodiversity Future Center, Piazza Marina, 61, Palermo, I-90133, Italy
| | - Pedro Martinez
- Department de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Av. Diagonal 643, Barcelona, 08028, Spain
- Institut Català de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys, Barcelona, 08010, Spain
| | - Kahina Mehennaoui
- Environmental Research and Innovation (ERIN) Department, Luxembourg Institute of Science and Technology (LIST), 41, rue du Brill, Belvaux, L-4422, Luxembourg
| | - Elif Oruc Ozcan
- Faculty of Arts and Science, Department of Biology, Cukurova University, Balcali, Saricam, Adana, 01330, Turkey
| | - Annalisa Pinsino
- National Research Council, Institute of Translational Pharmacology (IFT), National Research Council (CNR), Via Ugo La Malfa 153, Palermo, 90146, Italy
| | - Guy Paz
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO 2336 Sha'ar Palmer 1, Haifa, 3102201, Israel
| | - Baruch Rinkevich
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, PO 2336 Sha'ar Palmer 1, Haifa, 3102201, Israel
| | - Antonietta Spagnuolo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, 80121, Italy
| | - Michela Sugni
- Department of Environmental Science and Policy, University of Milan, Via Celoria 26, Milan, 20133, Italy
| | - Sébastien Cambier
- Environmental Research and Innovation (ERIN) Department, Luxembourg Institute of Science and Technology (LIST), 41, rue du Brill, Belvaux, L-4422, Luxembourg
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3
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Brodrick E, Jékely G. Photobehaviours guided by simple photoreceptor systems. Anim Cogn 2023; 26:1817-1835. [PMID: 37650997 PMCID: PMC10770211 DOI: 10.1007/s10071-023-01818-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/29/2023] [Accepted: 08/01/2023] [Indexed: 09/01/2023]
Abstract
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
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Affiliation(s)
- Emelie Brodrick
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Centre for Organismal Studies, University of Heidelberg, 69120, Heidelberg, Germany
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4
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Mercurio S, Bozzo M, Pennati A, Candiani S, Pennati R. Serotonin Receptors and Their Involvement in Melanization of Sensory Cells in Ciona intestinalis. Cells 2023; 12:cells12081150. [PMID: 37190059 DOI: 10.3390/cells12081150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/05/2023] [Accepted: 04/11/2023] [Indexed: 05/17/2023] Open
Abstract
Serotonin (5-hydroxytryptamine (5-HT)) is a biogenic monoamine with pleiotropic functions. It exerts its roles by binding to specific 5-HT receptors (5HTRs) classified into different families and subtypes. Homologs of 5HTRs are widely present in invertebrates, but their expression and pharmacological characterization have been scarcely investigated. In particular, 5-HT has been localized in many tunicate species but only a few studies have investigated its physiological functions. Tunicates, including ascidians, are the sister group of vertebrates, and data about the role of 5-HTRs in these organisms are thus important for understanding 5-HT evolution among animals. In the present study, we identified and described 5HTRs in the ascidian Ciona intestinalis. During development, they showed broad expression patterns that appeared consistent with those reported in other species. Then, we investigated 5-HT roles in ascidian embryogenesis exposing C. intestinalis embryos to WAY-100635, an antagonist of the 5HT1A receptor, and explored the affected pathways in neural development and melanogenesis. Our results contribute to unraveling the multifaceted functions of 5-HT, revealing its involvement in sensory cell differentiation in ascidians.
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Affiliation(s)
- Silvia Mercurio
- Department of Environmental Science and Policy, Università degli Studi di Milano, 20133 Milan, Italy
| | - Matteo Bozzo
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, Università degli Studi di Genova, 16132 Genoa, Italy
| | | | - Simona Candiani
- Dipartimento di Scienze della Terra, dell'Ambiente e della Vita, Università degli Studi di Genova, 16132 Genoa, Italy
| | - Roberta Pennati
- Department of Environmental Science and Policy, Università degli Studi di Milano, 20133 Milan, Italy
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5
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Hara T, Hasegawa S, Iwatani Y, Nishino AS. The trunk-tail junctional region in Ciona larvae autonomously expresses tail-beating bursts at ∼20 second intervals. J Exp Biol 2022; 225:275646. [PMID: 35678124 DOI: 10.1242/jeb.243828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 06/03/2022] [Indexed: 11/20/2022]
Abstract
Swimming locomotion in aquatic vertebrates, such as fish and tadpoles, is expressed through neuron networks in the spinal cord. These networks are arranged in parallel, ubiquitously distributed and mutually coupled along the spinal cord to express undulation patterns accommodated to various inputs into the networks. While these systems have been widely studied in vertebrate swimmers, their evolutionary origin along the chordate phylogeny remains unclear. Ascidians, representing a sister group of vertebrates, give rise to tadpole larvae that swim freely in seawater. In the present study, we examined the locomotor ability of the anterior and posterior body fragments of larvae of the ascidian Ciona that had been cut at an arbitrary position. Examination of more than 200 fragments revealed a necessary and sufficient body region that spanned only ∼10% of the body length and included the trunk-tail junction. 'Mid-piece' body fragments, which included the trunk-tail junctional region, but excluded most of the anterior trunk and posterior tail, autonomously expressed periodic tail-beating bursts at ∼20 s intervals. We compared the durations and intervals of tail-beating bursts expressed by mid-piece fragments, and also by whole larvae under different sensory conditions. The results suggest that body parts outside the mid-piece effect shortening of swimming intervals, particularly in the dark, and vary the burst duration. We propose that Ciona larvae express swimming behaviors by modifying autonomous and periodic locomotor drives that operate locally in the trunk-tail junctional region.
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Affiliation(s)
- Takashi Hara
- Department of Biology, Graduate School of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Shuya Hasegawa
- Department of Biology, Graduate School of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan
| | - Yasushi Iwatani
- Department of Science and Technology, Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan
| | - Atsuo S Nishino
- Department of Biology, Graduate School of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.,Department of Bioresources Science, United Graduate School of Agricultural Sciences, Iwate University, Hirosaki 036-8561, Japan
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6
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Fritzsch B, Martin PR. Vision and retina evolution: how to develop a retina. IBRO Neurosci Rep 2022; 12:240-248. [PMID: 35449767 PMCID: PMC9018162 DOI: 10.1016/j.ibneur.2022.03.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/30/2022] [Indexed: 12/29/2022] Open
Abstract
Early in vertebrate evolution, a single homeobox (Hox) cluster in basal chordates was quadrupled to generate the Hox gene clusters present in extant vertebrates. Here we ask how this expanded gene pool may have influenced the evolution of the visual system. We suggest that a single neurosensory cell type split into ciliated sensory cells (photoreceptors, which transduce light) and retinal ganglion cells (RGC, which project to the brain). In vertebrates, development of photoreceptors is regulated by the basic helix-loop-helix (bHLH) transcription factor Neurod1 whereas RGC development depends on Atoh7 and related bHLH genes. Lancelet (a basal chordate) does not express Neurod or Atoh7 and possesses a few neurosensory cells with cilia that reach out of the opening of the neural tube. Sea-squirts (Ascidians) do not express Neurod and express a different bHLH gene, Atoh8, that is likely expressed in the anterior vesicle. Recent data indicate the neurosensory cells in lancelets may correspond to three distinct eye fields in ascidians, which in turn may be the basis of the vertebrate retina, pineal and parapineal. In this review we contrast the genetic control of visual structure development in these chordates with that of basal vertebrates such as lampreys and hagfish, and jawed vertebrates. We propose an evolutionary sequence linking whole-genome duplications, initially to a split between photoreceptor and projection neurons (RGC) and subsequently between pineal and lateral eye structures.
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7
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Locascio A, Vassalli QA, Castellano I, Palumbo A. Novel Insights on Nitric Oxide Synthase and NO Signaling in Ascidian Metamorphosis. Int J Mol Sci 2022; 23:ijms23073505. [PMID: 35408864 PMCID: PMC8999111 DOI: 10.3390/ijms23073505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 03/11/2022] [Accepted: 03/20/2022] [Indexed: 02/05/2023] Open
Abstract
Nitric oxide (NO) is a pivotal signaling molecule involved in a wide range of physiological and pathological processes. We investigated NOS/NO localization patterns during the different stages of larval development in the ascidia Ciona robusta and evidenced a specific and temporally controlled pattern. NOS/NO expression starts in the most anterior sensory structures of the early larva and progressively moves towards the caudal portion as larval development and metamorphosis proceeds. We here highlight the pattern of NOS/NO expression in the central and peripheral nervous system of Ciona larvae which precisely follows the progression of neural signals of the central pattern generator necessary for the control of the movements of the larva towards the substrate. This highly dynamic localization profile perfectly matches with the central role played by NO from the first phase of settlement induction to the next control of swimming behavior, adhesion to substrate and progressive tissue resorption and reorganization of metamorphosis itself.
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Affiliation(s)
- Annamaria Locascio
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
| | - Quirino Attilio Vassalli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
| | - Immacolata Castellano
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, Via Pansini 5, 80131 Napoli, Italy;
| | - Anna Palumbo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
- Correspondence: (A.L.); (A.P.)
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8
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Olivo P, Palladino A, Ristoratore F, Spagnuolo A. Brain Sensory Organs of the Ascidian Ciona robusta: Structure, Function and Developmental Mechanisms. Front Cell Dev Biol 2021; 9:701779. [PMID: 34552923 PMCID: PMC8450388 DOI: 10.3389/fcell.2021.701779] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022] Open
Abstract
During evolution, new characters are designed by modifying pre-existing structures already present in ancient organisms. In this perspective, the Central Nervous System (CNS) of ascidian larva offers a good opportunity to analyze a complex phenomenon with a simplified approach. As sister group of vertebrates, ascidian tadpole larva exhibits a dorsal CNS, made up of only about 330 cells distributed into the anterior sensory brain vesicle (BV), connected to the motor ganglion (MG) and a caudal nerve cord (CNC) in the tail. Low number of cells does not mean, however, low complexity. The larval brain contains 177 neurons, for which a documented synaptic connectome is now available, and two pigmented organs, the otolith and the ocellus, controlling larval swimming behavior. The otolith is involved in gravity perception and the ocellus in light perception. Here, we specifically review the studies focused on the development of the building blocks of ascidians pigmented sensory organs, namely pigment cells and photoreceptor cells. We focus on what it is known, up to now, on the molecular bases of specification and differentiation of both lineages, on the function of these organs after larval hatching during pre-settlement period, and on the most cutting-edge technologies, like single cell RNAseq and genome editing CRISPR/CAS9, that, adapted and applied to Ciona embryos, are increasingly enhancing the tractability of Ciona for developmental studies, including pigmented organs formation.
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Affiliation(s)
- Paola Olivo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonio Palladino
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Filomena Ristoratore
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonietta Spagnuolo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
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9
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Borba C, Kourakis MJ, Schwennicke S, Brasnic L, Smith WC. Fold Change Detection in Visual Processing. Front Neural Circuits 2021; 15:705161. [PMID: 34497492 PMCID: PMC8419522 DOI: 10.3389/fncir.2021.705161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
Visual processing transforms the complexities of the visual world into useful information. Ciona, an invertebrate chordate and close relative of the vertebrates, has one of the simplest nervous systems known, yet has a range of visuomotor behaviors. This simplicity has facilitated studies linking behavior and neural circuitry. Ciona larvae have two distinct visuomotor behaviors - a looming shadow response and negative phototaxis. These are mediated by separate neural circuits that initiate from different clusters of photoreceptors, with both projecting to a CNS structure called the posterior brain vesicle (pBV). We report here that inputs from both circuits are processed to generate fold change detection (FCD) outputs. In FCD, the behavioral response scales with the relative fold change in input, but is invariant to the overall magnitude of the stimulus. Moreover, the two visuomotor behaviors have fundamentally different stimulus/response relationships - indicative of differing circuit strategies, with the looming shadow response showing a power relationship to fold change, while the navigation behavior responds linearly. Pharmacological modulation of the FCD response points to the FCD circuits lying outside of the visual organ (the ocellus), with the pBV being the most likely location. Consistent with these observations, the connectivity and properties of pBV interneurons conform to known FCD circuit motifs, but with different circuit architectures for the two circuits. The negative phototaxis circuit forms a putative incoherent feedforward loop that involves interconnecting cholinergic and GABAergic interneurons. The looming shadow circuit uses the same cholinergic and GABAergic interneurons, but with different synaptic inputs to create a putative non-linear integral feedback loop. These differing circuit architectures are consistent with the behavioral outputs of the two circuits. Finally, while some reports have highlighted parallels between the pBV and the vertebrate midbrain, suggesting a common origin for the two, others reports have disputed this, suggesting that invertebrate chordates lack a midbrain homolog. The convergence of visual inputs at the pBV, and its putative role in visual processing reported here and in previous publications, lends further support to the proposed common origin of the pBV and the vertebrate midbrain.
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Affiliation(s)
- Cezar Borba
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Matthew J Kourakis
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Shea Schwennicke
- College of Creative Studies, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Lorena Brasnic
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States.,Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - William C Smith
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States.,College of Creative Studies, University of California, Santa Barbara, Santa Barbara, CA, United States
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10
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Lemaire LA, Cao C, Yoon PH, Long J, Levine M. The hypothalamus predates the origin of vertebrates. SCIENCE ADVANCES 2021; 7:7/18/eabf7452. [PMID: 33910896 PMCID: PMC8081355 DOI: 10.1126/sciadv.abf7452] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 03/09/2021] [Indexed: 05/02/2023]
Abstract
The hypothalamus coordinates neuroendocrine functions in vertebrates. To explore its evolutionary origin, we describe integrated transcriptome/connectome brain maps for swimming tadpoles of Ciona, which serves as an approximation of the ancestral proto-vertebrate. This map features several cell types related to different regions of the vertebrate hypothalamus, including the mammillary nucleus, the arcuate nucleus, and magnocellular neurons. Coronet cells express melanopsin and share additional properties with the saccus vasculosus, a specialized region of the hypothalamus that mediates photoperiodism in nontropical fishes. Comparative transcriptome analyses identified orthologous cell types for mechanosensory switch neurons, and VP+ and VPR+ relay neurons in different regions of the mouse hypothalamus. These observations provide evidence that the hypothalamus predates the evolution of the vertebrate brain. We discuss the possibility that switch neurons, coronet cells, and FoxP+ /VPR+ relay neurons comprise a behavioral circuit that helps trigger metamorphosis of Ciona larvae in response to twilight.
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Affiliation(s)
- Laurence A Lemaire
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Chen Cao
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Peter H Yoon
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Juanjuan Long
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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11
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Vassalli QA, Colantuono C, Nittoli V, Ferraioli A, Fasano G, Berruto F, Chiusano ML, Kelsh RN, Sordino P, Locascio A. Onecut Regulates Core Components of the Molecular Machinery for Neurotransmission in Photoreceptor Differentiation. Front Cell Dev Biol 2021; 9:602450. [PMID: 33816460 PMCID: PMC8012850 DOI: 10.3389/fcell.2021.602450] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/11/2021] [Indexed: 11/13/2022] Open
Abstract
Photoreceptor cells (PRC) are neurons highly specialized for sensing light stimuli and have considerably diversified during evolution. The genetic mechanisms that underlie photoreceptor differentiation and accompanied the progressive increase in complexity and diversification of this sensory cell type are a matter of great interest in the field. A role of the homeodomain transcription factor Onecut (Oc) in photoreceptor cell formation is proposed throughout multicellular organisms. However, knowledge of the identity of the Oc downstream-acting factors that mediate specific tasks in the differentiation of the PRC remains limited. Here, we used transgenic perturbation of the Ciona robusta Oc protein to show its requirement for ciliary PRC differentiation. Then, transcriptome profiling between the trans-activation and trans-repression Oc phenotypes identified differentially expressed genes that are enriched in exocytosis, calcium homeostasis, and neurotransmission. Finally, comparison of RNA-Seq datasets in Ciona and mouse identifies a set of Oc downstream genes conserved between tunicates and vertebrates. The transcription factor Oc emerges as a key regulator of neurotransmission in retinal cell types.
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Affiliation(s)
- Quirino Attilio Vassalli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Chiara Colantuono
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Valeria Nittoli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Anna Ferraioli
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Giulia Fasano
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Federica Berruto
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Maria Luisa Chiusano
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Naples, Italy
- Department of Agriculture, Università degli Studi di Napoli Federico II, Portici, Italy
| | - Robert Neil Kelsh
- Department of Biology and Biochemistry and Centre for Regenerative Medicine, University of Bath, London, United Kingdom
| | - Paolo Sordino
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Annamaria Locascio
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
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12
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Transcription Factors of the bHLH Family Delineate Vertebrate Landmarks in the Nervous System of a Simple Chordate. Genes (Basel) 2020; 11:genes11111262. [PMID: 33114624 PMCID: PMC7693978 DOI: 10.3390/genes11111262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 10/12/2020] [Indexed: 02/07/2023] Open
Abstract
Tunicates are marine invertebrates whose tadpole-like larvae feature a highly simplified version of the chordate body plan. Similar to their distant vertebrate relatives, tunicate larvae develop a regionalized central nervous system and form distinct neural structures, which include a rostral sensory vesicle, a motor ganglion, and a caudal nerve cord. The sensory vesicle contains a photoreceptive complex and a statocyst, and based on the comparable expression patterns of evolutionarily conserved marker genes, it is believed to include proto-hypothalamic and proto-retinal territories. The evolutionarily conserved molecular fingerprints of these landmarks of the vertebrate brain consist of genes encoding for different transcription factors, and of the gene batteries that they control, and include several members of the bHLH family. Here we review the complement of bHLH genes present in the streamlined genome of the tunicate Ciona robusta and their current classification, and summarize recent studies on proneural bHLH transcription factors and their expression territories. We discuss the possible roles of bHLH genes in establishing the molecular compartmentalization of the enticing nervous system of this unassuming chordate.
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13
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Abstract
For centuries, the eye has fascinated scientists and philosophers alike, and as a result the visual system has always been at the forefront of integrating cutting-edge technology in research. We are again at a turning point at which technical advances have expanded the range of organisms we can study developmentally and deepened what we can learn. In this new era, we are finally able to understand eye development in animals across the phylogenetic tree. In this Review, we highlight six areas in comparative visual system development that address questions that are important for understanding the developmental basis of evolutionary change. We focus on the opportunities now available to biologists to study the developmental genetics, cell biology and morphogenesis that underlie the incredible variation of visual organs found across the Metazoa. Although decades of important work focused on gene expression has suggested homologies and potential evolutionary relationships between the eyes of diverse animals, it is time for developmental biologists to move away from this reductive approach. We now have the opportunity to celebrate the differences and diversity in visual organs found across animal development, and to learn what it can teach us about the fundamental principles of biological systems and how they are built.
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Affiliation(s)
- Kristen M Koenig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA 02138, USA
| | - Jeffrey M Gross
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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14
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Ryan K, Meinertzhagen IA. Neuronal identity: the neuron types of a simple chordate sibling, the tadpole larva of Ciona intestinalis. Curr Opin Neurobiol 2019; 56:47-60. [PMID: 30530111 PMCID: PMC6551260 DOI: 10.1016/j.conb.2018.10.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/30/2018] [Indexed: 11/19/2022]
Abstract
Neurons of the sparsely populated nervous system of the tadpole larva in the tunicate Ciona intestinalis, a chordate sibling, are known from sporadic previous studies but especially two recent reports that document the connectome of both the central and peripheral nervous systems at EM level. About 330 CNS cells comprise mostly ciliated ependymal cells, with ∼180 neurons that constitute about 50 morphologically distinguishable types. The neurons reveal various chordate characters amid many features that are idiosyncratic. Most neurons are ciliated and lack dendrites, some even lack an axon. Synapses mostly form en passant between axons, and resemble those in basal invertebrates; some are dyads and all have heterogenous synaptic vesicle populations. Each neuron has on average 49 synapses with other cells; these constitute a synaptic network of unpredicted complexity.
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Affiliation(s)
- Kerrianne Ryan
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
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15
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Kourakis MJ, Borba C, Zhang A, Newman-Smith E, Salas P, Manjunath B, Smith WC. Parallel visual circuitry in a basal chordate. eLife 2019; 8:44753. [PMID: 30998184 PMCID: PMC6499539 DOI: 10.7554/elife.44753] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 04/11/2019] [Indexed: 12/28/2022] Open
Abstract
A common CNS architecture is observed in all chordates, from vertebrates to basal chordates like the ascidian Ciona. Ciona stands apart among chordates in having a complete larval connectome. Starting with visuomotor circuits predicted by the Ciona connectome, we used expression maps of neurotransmitter use with behavioral assays to identify two parallel visuomotor circuits that are responsive to different components of visual stimuli. The first circuit is characterized by glutamatergic photoreceptors and responds to the direction of light. These photoreceptors project to cholinergic motor neurons, via two tiers of cholinergic interneurons. The second circuit responds to changes in ambient light and mediates an escape response. This circuit uses GABAergic photoreceptors which project to GABAergic interneurons, and then to cholinergic interneurons. Our observations on the behavior of larvae either treated with a GABA receptor antagonist or carrying a mutation that eliminates photoreceptors indicate the second circuit is disinhibitory.
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Affiliation(s)
- Matthew J Kourakis
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, United States
| | - Cezar Borba
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, United States
| | - Angela Zhang
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, United States
| | - Erin Newman-Smith
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, United States.,Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, United States
| | - Priscilla Salas
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, United States
| | - B Manjunath
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, United States
| | - William C Smith
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, United States.,Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, United States
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16
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Sharma S, Wang W, Stolfi A. Single-cell transcriptome profiling of the Ciona larval brain. Dev Biol 2019; 448:226-236. [PMID: 30392840 PMCID: PMC6487232 DOI: 10.1016/j.ydbio.2018.09.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/10/2018] [Accepted: 09/10/2018] [Indexed: 11/27/2022]
Abstract
The tadpole-type larva of Ciona has emerged as an intriguing model system for the study of neurodevelopment. The Ciona intestinalis connectome has been recently mapped, revealing the smallest central nervous system (CNS) known in any chordate, with only 177 neurons. This minimal CNS is highly reminiscent of larger CNS of vertebrates, sharing many conserved developmental processes, anatomical compartments, neuron subtypes, and even specific neural circuits. Thus, the Ciona tadpole offers a unique opportunity to understand the development and wiring of a chordate CNS at single-cell resolution. Here we report the use of single-cell RNAseq to profile the transcriptomes of single cells isolated by fluorescence-activated cell sorting (FACS) from the whole brain of Ciona robusta (formerly intestinalis Type A) larvae. We have also compared these profiles to bulk RNAseq data from specific subsets of brain cells isolated by FACS using cell type-specific reporter plasmid expression. Taken together, these datasets have begun to reveal the compartment- and cell-specific gene expression patterns that define the organization of the Ciona larval brain.
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Affiliation(s)
- Sarthak Sharma
- Georgia Institute of Technology, School of Biological Sciences, Atlanta, GA, United States
| | - Wei Wang
- New York University, Department of Biology, New York, NY, United States
| | - Alberto Stolfi
- Georgia Institute of Technology, School of Biological Sciences, Atlanta, GA, United States.
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17
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Oonuma K, Kusakabe TG. Spatio-temporal regulation of Rx and mitotic patterns shape the eye-cup of the photoreceptor cells in Ciona. Dev Biol 2018; 445:245-255. [PMID: 30502325 DOI: 10.1016/j.ydbio.2018.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/18/2018] [Accepted: 11/18/2018] [Indexed: 10/27/2022]
Abstract
The ascidian larva has a pigmented ocellus comprised of a cup-shaped array of approximately 30 photoreceptor cells, a pigment cell, and three lens cells. Morphological, physiological and molecular evidence has suggested evolutionary kinship between the ascidian larval photoreceptors and vertebrate retinal and/or pineal photoreceptors. Rx, an essential factor for vertebrate photoreceptor development, has also been suggested to be involved in the development of the ascidian photoreceptor cells, but a recent revision of the photoreceptor cell lineage raised a crucial discrepancy between the reported expression patterns of Rx and the cell lineage. Here, we report spatio-temporal expression patterns of Rx at single-cell resolution along with mitotic patterns up to the final division of the photoreceptor-lineage cells in Ciona. The expression of Rx commences in non-photoreceptor a-lineage cells on the right side of the anterior sensory vesicle at the early tailbud stage. At the mid tailbud stage, Rx begins to be expressed in the A-lineage photoreceptor cell progenitors located on the right side of the posterior sensory vesicle. Thus, Rx is specifically but not exclusively expressed in the photoreceptor-lineage cells in the ascidian embryo. Two cis-regulatory modules are shown to be important for the photoreceptor-lineage expression of Rx. The cell division patterns of the photoreceptor-lineage cells rationally explain the generation of the cup-shaped structure of the pigmented ocellus. The present findings demonstrate the complete cell lineage of the ocellus photoreceptor cells and provide a framework elucidating the molecular and cellular mechanisms of photoreceptor development in Ciona.
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Affiliation(s)
- Kouhei Oonuma
- Institute for Integrative Neurobiology and Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan.
| | - Takehiro G Kusakabe
- Institute for Integrative Neurobiology and Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan.
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18
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Horie T, Horie R, Chen K, Cao C, Nakagawa M, Kusakabe TG, Satoh N, Sasakura Y, Levine M. Regulatory cocktail for dopaminergic neurons in a protovertebrate identified by whole-embryo single-cell transcriptomics. Genes Dev 2018; 32:1297-1302. [PMID: 30228204 PMCID: PMC6169837 DOI: 10.1101/gad.317669.118] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 08/02/2018] [Indexed: 01/09/2023]
Abstract
The CNS of the protovertebrate Ciona intestinalis contains a single cluster of dopaminergic (DA) neurons, the coronet cells, which have been likened to the hypothalamus of vertebrates. Whole-embryo single-cell RNA sequencing (RNA-seq) assays identified Ptf1a as the most strongly expressed cell-specific transcription factor (TF) in DA/coronet cells. Knockdown of Ptf1a activity results in their loss, while misexpression results in the appearance of supernumerary DA/coronet cells. Photoreceptor cells and ependymal cells are the most susceptible to transformation, and both cell types express high levels of Meis Coexpression of both Ptf1a and Meis caused the wholesale transformation of the entire CNS into DA/coronet cells. We therefore suggest that the reiterative use of functional manipulations and single-cell RNA-seq assays is an effective means for the identification of regulatory cocktails underlying the specification of specific cell identities.
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Affiliation(s)
- Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
- Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology (PREST), Kawaguchi, Saitama 332-0012, Japan
| | - Ryoko Horie
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Kai Chen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Chen Cao
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
| | - Masashi Nakagawa
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Kamigori, Ako-gun, Hyogo 678-1297, Japan
| | - Takehiro G Kusakabe
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Hyogo 658-8501, Japan
- Institute for Integrative Neurobiology, Konan University, Kobe, Hyogo 658-8501, Japan
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka 415-0025, Japan
| | - Michael Levine
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
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19
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Messinetti S, Mercurio S, Pennati R. Bisphenol A affects neural development of the ascidian Ciona robusta. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 331:5-16. [PMID: 30218549 DOI: 10.1002/jez.2230] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 08/06/2018] [Accepted: 08/21/2018] [Indexed: 11/06/2022]
Abstract
Bisphenol A (BPA) is an organic pollutant derived from plastic degradation that has numerous and variable adverse effects on human health and wildlife. In particular, it has been reported that BPA can alter reproductive processes and nervous system development in vertebrates. Considering BPA presence in marine environment and the scant data available on its interaction with nervous system development, we analyzed the effect of BPA exposure on sperm viability, fertilization, embryogenesis, and neural differentiation of the ascidian Ciona robusta. Ascidians are members of the Phylum Tunicata, the sister group of Vertebrata, sharing with them fundamental developmental processes. Our results showed that first cell division was altered starting from 5 µM concentration. Lethal concentration (LC 50 ) was estimated to be 5.2 µM. Larvae developed from treated embryos showed specific malformations to the pigment cells even at 0.1 µM, corresponding to the highest environmental concentration reported so far. Moreover, GABAergic and dopaminergic neurons proved to be target organs of BPA teratogenic action, in accordance with similar results reported in vertebrate animal models. Overall, our results suggest that BPA can exert its effects on nervous system acting on different pathways and underline that C. robusta is a valuable invertebrate animal model for preliminary screenings of effects of pollutants on vertebrates.
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Affiliation(s)
- Silvia Messinetti
- Department of Environmental Science and Policy, Università degli Studi di Milano, Italy
| | - Silvia Mercurio
- Department of Environmental Science and Policy, Università degli Studi di Milano, Italy
| | - Roberta Pennati
- Department of Environmental Science and Policy, Università degli Studi di Milano, Italy
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20
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Salas P, Vinaithirthan V, Newman-Smith E, Kourakis MJ, Smith WC. Photoreceptor specialization and the visuomotor repertoire of the primitive chordate Ciona. J Exp Biol 2018; 221:jeb177972. [PMID: 29511068 PMCID: PMC5963834 DOI: 10.1242/jeb.177972] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 02/22/2018] [Indexed: 01/06/2023]
Abstract
The swimming tadpole larva of Ciona has one of the simplest central nervous systems (CNSs) known, with only 177 neurons. Despite its simplicity, the Ciona CNS has a common structure with the CNS of its close chordate relatives, the vertebrates. The recent completion of a larval Ciona CNS connectome creates enormous potential for detailed understanding of chordate CNS function, yet our understanding of Ciona larval behavior is incomplete. We show here that Ciona larvae have a surprisingly rich and dynamic set of visual responses, including a looming-object escape behavior characterized by erratic circular swims, as well as negative phototaxis characterized by sustained directional swims. Making use of mutant lines, we show that these two behaviors are mediated by distinct groups of photoreceptors. The Ciona connectome predicts that these two behavioral responses should act through distinct, but overlapping, visuomotor pathways, and that the escape behavior is likely to be integrated into a broader startle behavior.
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Affiliation(s)
- Priscilla Salas
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Vall Vinaithirthan
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Erin Newman-Smith
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Matthew J Kourakis
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - William C Smith
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
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21
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Nishino A. Morphology and Physiology of the Ascidian Nervous Systems and the Effectors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29542090 DOI: 10.1007/978-981-10-7545-2_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurobiology in ascidians has made many advances. Ascidians have offered natural advantages to researchers, including fecundity, structural simplicity, invariant morphology, and fast and stereotyped developmental processes. The researchers have also accumulated on this animal a great deal of knowledge, genomic resources, and modern genetic techniques. A recent connectomic analysis has shown an ultimately resolved image of the larval nervous system, whereas recent applications of live imaging and optogenetics have clarified the functional organization of the juvenile nervous system. Progress in resources and techniques have provided convincing ways to deepen what we have wanted to know about the nervous systems of ascidians. Here, the research history and the current views regarding ascidian nervous systems are summarized.
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Affiliation(s)
- Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
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22
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Evolutionary steps involving counterion displacement in a tunicate opsin. Proc Natl Acad Sci U S A 2017; 114:6028-6033. [PMID: 28533401 DOI: 10.1073/pnas.1701088114] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ci-opsin1 is a visible light-sensitive opsin present in the larval ocellus of an ascidian, Ciona intestinalis This invertebrate opsin belongs to the vertebrate visual and nonvisual opsin groups in the opsin phylogenetic tree. Ci-opsin1 contains candidate counterions (glutamic acid residues) at positions 113 and 181; the former is a newly acquired position in the vertebrate visual opsin lineage, whereas the latter is an ancestral position widely conserved among invertebrate opsins. Here, we show that Glu113 and Glu181 in Ci-opsin1 act synergistically as counterions, which imparts molecular properties to Ci-opsin1 intermediate between those of vertebrate- and invertebrate-type opsins. Synergy between the counterions in Ci-opsin1 was demonstrated by E113Q and E181Q mutants that exhibit a pH-dependent spectral shift, whereas only the E113Q mutation in vertebrate rhodopsin yields this spectral shift. On absorbing light, Ci-opsin1 forms an equilibrium between two intermediates with protonated and deprotonated Schiff bases, namely the MI-like and MII-like intermediates, respectively. Adding G protein caused the equilibrium to shift toward the MI-like intermediate, indicating that Ci-opsin1 has a protonated Schiff base in its active state, like invertebrate-type opsins. Ci-opsin1's G protein activation efficiency is between the efficiencies of vertebrate- and invertebrate-type opsins. Interestingly, the E113Y and E181S mutations change the molecular properties of Ci-opsin1 into those resembling invertebrate-type or bistable opsins and vertebrate ancient/vertebrate ancient-long or monostable opsins, respectively. These results strongly suggest that acquisition of counterion Glu113 changed the molecular properties of visual opsin in a vertebrate/tunicate common ancestor as a crucial step in the evolution of vertebrate visual opsins.
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23
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Kusakabe TG. Identifying Vertebrate Brain Prototypes in Deuterostomes. DIVERSITY AND COMMONALITY IN ANIMALS 2017. [DOI: 10.1007/978-4-431-56469-0_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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24
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Ryan K, Lu Z, Meinertzhagen IA. The CNS connectome of a tadpole larva of Ciona intestinalis (L.) highlights sidedness in the brain of a chordate sibling. eLife 2016; 5. [PMID: 27921996 PMCID: PMC5140270 DOI: 10.7554/elife.16962] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/17/2016] [Indexed: 12/12/2022] Open
Abstract
Left-right asymmetries in brains are usually minor or cryptic. We report brain asymmetries in the tiny, dorsal tubular nervous system of the ascidian tadpole larva, Ciona intestinalis. Chordate in body plan and development, the larva provides an outstanding example of brain asymmetry. Although early neural development is well studied, detailed cellular organization of the swimming larva's CNS remains unreported. Using serial-section EM we document the synaptic connectome of the larva's 177 CNS neurons. These formed 6618 synapses including 1772 neuromuscular junctions, augmented by 1206 gap junctions. Neurons are unipolar with at most a single dendrite, and few synapses. Some synapses are unpolarised, others form reciprocal or serial motifs; 922 were polyadic. Axo-axonal synapses predominate. Most neurons have ciliary organelles, and many features lack structural specialization. Despite equal cell numbers on both sides, neuron identities and pathways differ left/right. Brain vesicle asymmetries include a right ocellus and left coronet cells.
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Affiliation(s)
- Kerrianne Ryan
- Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, Canada.,Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Canada
| | - Zhiyuan Lu
- Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, Canada.,Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Canada
| | - Ian A Meinertzhagen
- Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, Canada.,Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Canada
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25
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Oonuma K, Tanaka M, Nishitsuji K, Kato Y, Shimai K, Kusakabe TG. Revised lineage of larval photoreceptor cells in Ciona reveals archetypal collaboration between neural tube and neural crest in sensory organ formation. Dev Biol 2016; 420:178-185. [PMID: 27789227 DOI: 10.1016/j.ydbio.2016.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/23/2016] [Accepted: 10/23/2016] [Indexed: 01/20/2023]
Abstract
The Ciona intestinalis larva has two distinct photoreceptor organs, a conventional pigmented ocellus and a nonpigmented ocellus, that are asymmetrically situated in the brain. The ciliary photoreceptor cells of these ocelli resemble visual cells of the vertebrate retina. Precise elucidation of the lineage of the photoreceptor cells will be key to understanding the developmental mechanisms of these cells as well as the evolutionary relationships between the photoreceptor organs of ascidians and vertebrates. Photoreceptor cells of the pigmented ocellus have been thought to develop from anterior animal (a-lineage) blastomeres, whereas the developmental origin of the nonpigmented ocellus has not been determined. Here, we show that the photoreceptor cells of both ocelli develop from the right anterior vegetal hemisphere: those of the pigmented ocellus from the right A9.14 cell and those of the nonpigmented ocellus from the right A9.16 cell. The pigmented ocellus is formed by a combination of two lineages of cells with distinct embryonic origins: the photoreceptor cells originate from a medial portion of the A-lineage neural plate, while the pigment cell originates from the lateral edge of the a-lineage neural plate. In light of the recently proposed close evolutionary relationship between the ocellus pigment cell of ascidians and the cephalic neural crest of vertebrates, the ascidian ocellus may represent a prototypic contribution of the neural crest to a cranial sensory organ.
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Affiliation(s)
- Kouhei Oonuma
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Moeko Tanaka
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Koki Nishitsuji
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Yumiko Kato
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Kotaro Shimai
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Takehiro G Kusakabe
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan.
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26
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Randel N, Jékely G. Phototaxis and the origin of visual eyes. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150042. [PMID: 26598725 DOI: 10.1098/rstb.2015.0042] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Vision allows animals to detect spatial differences in environmental light levels. High-resolution image-forming eyes evolved from low-resolution eyes via increases in photoreceptor cell number, improvements in optics and changes in the neural circuits that process spatially resolved photoreceptor input. However, the evolutionary origins of the first low-resolution visual systems have been unclear. We propose that the lowest resolving (two-pixel) visual systems could initially have functioned in visual phototaxis. During visual phototaxis, such elementary visual systems compare light on either side of the body to regulate phototactic turns. Another, even simpler and non-visual strategy is characteristic of helical phototaxis, mediated by sensory-motor eyespots. The recent mapping of the complete neural circuitry (connectome) of an elementary visual system in the larva of the annelid Platynereis dumerilii sheds new light on the possible paths from non-visual to visual phototaxis and to image-forming vision. We outline an evolutionary scenario focusing on the neuronal circuitry to account for these transitions. We also present a comprehensive review of the structure of phototactic eyes in invertebrate larvae and assign them to the non-visual and visual categories. We propose that non-visual systems may have preceded visual phototactic systems in evolution that in turn may have repeatedly served as intermediates during the evolution of image-forming eyes.
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Affiliation(s)
- Nadine Randel
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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The central nervous system of ascidian larvae. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2016; 5:538-61. [DOI: 10.1002/wdev.239] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/05/2016] [Accepted: 04/09/2016] [Indexed: 11/07/2022]
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Esposito R, Racioppi C, Pezzotti MR, Branno M, Locascio A, Ristoratore F, Spagnuolo A. The ascidian pigmented sensory organs: structures and developmental programs. Genesis 2014; 53:15-33. [PMID: 25382437 DOI: 10.1002/dvg.22836] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 01/25/2023]
Abstract
The recent advances on ascidian pigment sensory organ development and function represent a fascinating platform to get insight on the basic programs of chordate eye formation. This review aims to summarize current knowledge, at the structural and molecular levels, on the two main building blocks of ascidian light sensory organ, i.e. pigment cells and photoreceptor cells. The unique features of these structures (e.g., simplicity and well characterized cell lineage) are indeed making it possible to dissect the developmental programs at single cell resolution and will soon provide a panel of molecular tools to be exploited for a deep developmental and comparative-evolutionary analysis.
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Affiliation(s)
- R Esposito
- Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, NAPOLI, Italy
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29
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Russo MT, Racioppi C, Zanetti L, Ristoratore F. Expression of a single prominin homolog in the embryo of the model chordate Ciona intestinalis. Gene Expr Patterns 2014; 15:38-45. [PMID: 24755348 DOI: 10.1016/j.gep.2014.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 12/21/2022]
Abstract
Prominins are a family of pentaspan transmembrane glycoproteins, expressed in various types of cells, including stem and cancer stem cells in mammals. Prominin-1 is critical in generating and maintaining the structure of the photoreceptors in the eye since mutations in the PROM1 gene are associated with retinal and macular degeneration in human. In this study, we identified a single prominin homolog, Ci-prom1/2, in the model chordate the ascidian Ciona intestinalis and characterized Ci-prom1/2 expression profile in relation to photoreceptor differentiation during Ciona embryonic development. In situ hybridization experiments show Ci-prom1/2 transcripts localized in the developing central nervous system, predominantly in photoreceptor cell precursors as early as neurula stage and expression is maintained through larva stage in photoreceptor cells around the simple eye. We also isolated the regulatory region responsible for the specific spatio-temporal expression of the Ci-prom1/2 in photoreceptor cell lineage. Collectively, we report that Ci-prom1/2 is a novel molecular marker for ascidian photoreceptor cells and might represent a potential source to enlarge the knowledge about the function of prominin family in photoreceptor cell evolution and development.
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Affiliation(s)
- Monia T Russo
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Claudia Racioppi
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Laura Zanetti
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Filomena Ristoratore
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy.
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Katsumoto S, Hatta K, Nakagawa M. Brief hypo-osmotic shock causes test cell death, prevents neurula rotation, and disrupts left-right asymmetry in Ciona intestinalis. Zoolog Sci 2013; 30:352-9. [PMID: 23646939 DOI: 10.2108/zsj.30.352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ascidian Ciona intestinalis tadpole larvae exhibit left-right asymmetry. The photoreceptors are situated on the right side of the sensory vesicle, and the tail curls along the left side of the trunk within the chorion. In tailbud embryos, the Ci-pitx gene is expressed in the left-side epidermis. It was previously reported that embryos generated from naked eggs, which lack the chorionic membrane and accessory cells (follicle cells attached to the outside of the chorion and test cells covering the inner surface of the chorion), show bilateral expression of Ci-pitx. This suggested that the chorion or accessory cells are needed for generation of asymmetry. Here, we show that a brief treatment with 60% artificial seawater (ASW) before, but not after, the neurula stage results in bilateral expression of Ci-pitx in the chorion of tailbud embryos, loss of follicle cells, and randomization of both the direction of tail curling and the locations of photoreceptors in larvae. This treatment also impaired the transient counterclockwise rotation within the chorion at the neurula stage. Nearly all test cells in the chorion died following 60% ASW treatment. These results suggest that dead test cells blocked the neural rotation and impaired left-right asymmetry. We also showed that tailbud embryos and larvae generated from defolliculated eggs produced by 80% ASW treatment, in which the test cells were alive, showed normal left-right asymmetry, suggesting that the follicle cells were not essential for asymmetric morphogenesis.
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Affiliation(s)
- Shimpei Katsumoto
- Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamigori, Akoh-gun, Japan
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31
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Slingsby C, Wistow GJ, Clark AR. Evolution of crystallins for a role in the vertebrate eye lens. Protein Sci 2013; 22:367-80. [PMID: 23389822 PMCID: PMC3610043 DOI: 10.1002/pro.2229] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 01/16/2013] [Accepted: 01/17/2013] [Indexed: 12/18/2022]
Abstract
The camera eye lens of vertebrates is a classic example of the re-engineering of existing protein components to fashion a new device. The bulk of the lens is formed from proteins belonging to two superfamilies, the α-crystallins and the βγ-crystallins. Tracing their ancestry may throw light on the origin of the optics of the lens. The α-crystallins belong to the ubiquitous small heat shock proteins family that plays a protective role in cellular homeostasis. They form enormous polydisperse oligomers that challenge modern biophysical methods to uncover the molecular basis of their assembly structure and chaperone-like protein binding function. It is argued that a molecular phenotype of a dynamic assembly suits a chaperone function as well as a structural role in the eye lens where the constraint of preventing protein condensation is paramount. The main cellular partners of α-crystallins, the β- and γ-crystallins, have largely been lost from the animal kingdom but the superfamily is hugely expanded in the vertebrate eye lens. Their structures show how a simple Greek key motif can evolve rapidly to form a complex array of monomers and oligomers. Apart from remaining transparent, a major role of the partnership of α-crystallins with β- and γ-crystallins in the lens is to form a refractive index gradient. Here, we show some of the structural and genetic features of these two protein superfamilies that enable the rapid creation of different assembly states, to match the rapidly changing optical needs among the various vertebrates.
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Affiliation(s)
- Christine Slingsby
- Department of Biological Sciences, Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom.
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Kusakabe TG, Sakai T, Aoyama M, Kitajima Y, Miyamoto Y, Takigawa T, Daido Y, Fujiwara K, Terashima Y, Sugiuchi Y, Matassi G, Yagisawa H, Park MK, Satake H, Tsuda M. A conserved non-reproductive GnRH system in chordates. PLoS One 2012; 7:e41955. [PMID: 22848672 PMCID: PMC3407064 DOI: 10.1371/journal.pone.0041955] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 06/27/2012] [Indexed: 01/28/2023] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is a neuroendocrine peptide that plays a central role in the vertebrate hypothalamo-pituitary axis. The roles of GnRH in the control of vertebrate reproductive functions have been established, while its non-reproductive function has been suggested but less well understood. Here we show that the tunicate Ciona intestinalis has in its non-reproductive larval stage a prominent GnRH system spanning the entire length of the nervous system. Tunicate GnRH receptors are phylogenetically closest to vertebrate GnRH receptors, yet functional analysis of the receptors revealed that these simple chordates have evolved a unique GnRH system with multiple ligands and receptor heterodimerization enabling complex regulation. One of the gnrh genes is conspicuously expressed in the motor ganglion and nerve cord, which are homologous structures to the hindbrain and spinal cord of vertebrates. Correspondingly, GnRH receptor genes were found to be expressed in the tail muscle and notochord of embryos, both of which are phylotypic axial structures along the nerve cord. Our findings suggest a novel non-reproductive role of GnRH in tunicates. Furthermore, we present evidence that GnRH-producing cells are present in the hindbrain and spinal cord of the medaka, Oryzias latipes, thereby suggesting the deep evolutionary origin of a non-reproductive GnRH system in chordates.
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Affiliation(s)
- Takehiro G. Kusakabe
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Tsubasa Sakai
- Division of Biomolecular Research, Suntory Institute for Bioorganic Research, Shimamoto, Osaka, Japan
| | - Masato Aoyama
- Division of Biomolecular Research, Suntory Institute for Bioorganic Research, Shimamoto, Osaka, Japan
| | - Yuka Kitajima
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Yuki Miyamoto
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Toru Takigawa
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Yutaka Daido
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Kentaro Fujiwara
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Yasuko Terashima
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Yoko Sugiuchi
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
| | - Giorgio Matassi
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe, Japan
- Department of Agriculture and Environmental Sciences, University of Udine, Udine, Italy
| | - Hitoshi Yagisawa
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Min Kyun Park
- Department of Biological Sciences, Graduate School of Science, the University of Tokyo, Tokyo, Japan
| | - Honoo Satake
- Division of Biomolecular Research, Suntory Institute for Bioorganic Research, Shimamoto, Osaka, Japan
| | - Motoyuki Tsuda
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Kagawa, Japan
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Razy-Krajka F, Brown ER, Horie T, Callebert J, Sasakura Y, Joly JS, Kusakabe TG, Vernier P. Monoaminergic modulation of photoreception in ascidian: evidence for a proto-hypothalamo-retinal territory. BMC Biol 2012; 10:45. [PMID: 22642675 PMCID: PMC3414799 DOI: 10.1186/1741-7007-10-45] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/29/2012] [Indexed: 12/12/2022] Open
Abstract
Background The retina of craniates/vertebrates has been proposed to derive from a photoreceptor prosencephalic territory in ancestral chordates, but the evolutionary origin of the different cell types making the retina is disputed. Except for photoreceptors, the existence of homologs of retinal cells remains uncertain outside vertebrates. Methods The expression of genes expressed in the sensory vesicle of the ascidian Ciona intestinalis including those encoding components of the monoaminergic neurotransmission systems, was analyzed by in situ hybridization or in vivo transfection of the corresponding regulatory elements driving fluorescent reporters. Modulation of photic responses by monoamines was studied by electrophysiology combined with pharmacological treatments. Results We show that many molecular characteristics of dopamine-synthesizing cells located in the vicinity of photoreceptors in the sensory vesicle of the ascidian Ciona intestinalis are similar to those of amacrine dopamine cells of the vertebrate retina. The ascidian dopamine cells share with vertebrate amacrine cells the expression of the key-transcription factor Ptf1a, as well as that of dopamine-synthesizing enzymes. Surprisingly, the ascidian dopamine cells accumulate serotonin via a functional serotonin transporter, as some amacrine cells also do. Moreover, dopamine cells located in the vicinity of the photoreceptors modulate the light-off induced swimming behavior of ascidian larvae by acting on alpha2-like receptors, instead of dopamine receptors, supporting a role in the modulation of the photic response. These cells are located in a territory of the ascidian sensory vesicle expressing genes found both in the retina and the hypothalamus of vertebrates (six3/6, Rx, meis, pax6, visual cycle proteins). Conclusion We propose that the dopamine cells of the ascidian larva derive from an ancestral multifunctional cell population located in the periventricular, photoreceptive field of the anterior neural tube of chordates, which also gives rise to both anterior hypothalamus and the retina in craniates/vertebrates. It also shows that the existence of multiple cell types associated with photic responses predates the formation of the vertebrate retina.
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Affiliation(s)
- Florian Razy-Krajka
- Neurobiology and Development, UPR, Institut de Neurobiologie Alfred Fessard, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
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Wagner E, Levine M. FGF signaling establishes the anterior border of the Ciona neural tube. Development 2012; 139:2351-9. [PMID: 22627287 DOI: 10.1242/dev.078485] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The Ciona tadpole is constructed from simple, well-defined cell lineages governed by provisional gene networks that have been defined via extensive gene disruption assays. Here, we examine the patterning of the anterior neural plate, which produces placodal derivatives such as the adhesive palps and stomodeum, as well as the sensory vesicle (simple brain) of the Ciona tadpole. Evidence is presented that the doublesex-related gene DMRT is expressed throughout the anterior neural plate of neurulating embryos. It leads to the activation of FoxC and ZicL in the palp placode and anterior neural tube, respectively. This differential expression depends on FGF signaling, which inhibits FoxC expression in the anterior neural tube. Inhibition of FGF signaling leads to expanded expression of FoxC, the loss of ZicL, and truncation of the anterior neural tube.
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Affiliation(s)
- Eileen Wagner
- Center for Integrative Genomics, Division of Genetics, Genomics, and Development, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA.
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D'Aniello E, Pezzotti MR, Locascio A, Branno M. Onecut is a direct neural-specific transcriptional activator of Rx in Ciona intestinalis. Dev Biol 2011; 355:358-71. [PMID: 21600895 DOI: 10.1016/j.ydbio.2011.05.584] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 04/21/2011] [Accepted: 05/04/2011] [Indexed: 11/28/2022]
Abstract
Retinal homeobox (Rx) genes play a crucial and conserved role in the development of the anterior neural plate of metazoans. During chordate evolution, they have also acquired a novel function in the control of eye formation and neurogenesis. To characterize the Rx genetic cascade and shed light on the mechanisms that led to the acquisition of this new role in eye development, we studied Rx transcriptional regulation using the ascidian, Ciona intestinalis. Through deletion analysis of the Ci-Rx promoter, we have identified two distinct enhancer elements able to induce Ci-Rx specific expression in the anterior part of the CNS and in the photosensory organ at tailbud and larva stages. Bioinformatic analysis highlighted the presence of two Onecut binding sites contained in these enhancers, so we explored the role of this transcription factor in the regulation of Ci-Rx. By in situ hybridization, we first confirmed that these genes are co-expressed in the same cells. Through a series of in vivo and in vitro experiments, we then demonstrated that the two Onecut sites are responsible for enhancer activation in Ci-Rx endogenous territories. We also demonstrated in vivo that Onecut misexpression is able to induce ectopic activation of the Rx promoter. Finally, we demonstrated that Ci-Onecut is able to promote Ci-Rx expression in the sensory vesicle. Together, these results support the conclusion that in Ciona embryogenesis, Ci-Rx expression is under the control of the Onecut transcription factor and that this factor is necessary and sufficient to specifically activate Ci-Rx through two enhancer elements.
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Affiliation(s)
- Enrico D'Aniello
- Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
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36
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Stolfi A, Levine M. Neuronal subtype specification in the spinal cord of a protovertebrate. Development 2011; 138:995-1004. [DOI: 10.1242/dev.061507] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The visceral ganglion (VG) comprises the basic motor pool of the swimming ascidian tadpole and has been proposed to be homologous to the spinal cord of vertebrates. Here, we use cis-regulatory modules, or enhancers, from transcription factor genes expressed in single VG neuronal precursors to label and identify morphologically distinct moto- and interneuron subtypes in the Ciona intestinalis tadpole larva. We also show that the transcription factor complement present in each differentiating neuron correlates with its unique morphology. Forced expression of putative interneuron markers Dmbx and Vsx results in ectopic interneuron-like cells at the expense of motoneurons. Furthermore, by perturbing upstream signaling events, we can change the transcription factor expression profile and subsequent identity of the different precursors. Perturbation of FGF signaling transforms the entire VG into Vsx+/Pitx+ putative cholinergic interneurons, while perturbation of Notch signaling results in duplication of Dmbx+ decussating interneurons. These experiments demonstrate the connection between transcriptional regulation and the neuronal subtype diversity underlying swimming behavior in a simple chordate.
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Affiliation(s)
- Alberto Stolfi
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Michael Levine
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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Ohta N, Horie T, Satoh N, Sasakura Y. Transposon-mediated enhancer detection reveals the location, morphology and development of the cupular organs, which are putative hydrodynamic sensors, in the ascidian Ciona intestinalis. Zoolog Sci 2011; 27:842-50. [PMID: 21039122 DOI: 10.2108/zsj.27.842] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The adult of the ascidian Ciona intestinalis has cupular organs, i.e., putative hydrodynamic sensors, at the atrial epithelium. The cupular organ consists of support cells and sensory neurons, and it extends a gelatinous matrix, known as a cupula, toward the atrial cavity. These characteristics are shared with sensory hair cells in the vertebrate inner ear and lateral line neuromasts in fish and amphibians, which suggests an evolutionary link between the cupular organ and these vertebrate hydrodynamic sensors. In the present study, we have isolated and investigated two transposon-mediated enhancer detection lines that showed GFP expression in support cells of the cupular organs. Using the enhancer detection lines and neuron marker transgenic lines, we describe the position, morphology, and development of the cupular organs. Cupular organs were found at the atrial epithelium, but not in the branchial epithelium. We found that cupular organs are also present along the dorsal fold and the gonoducts. The cells lining the pre-atrial opening in juveniles are presumably precursor cells of the cupular organ. To our knowledge, the present study is the first precise description of the ascidian cupular organ, providing evidence that may help to resolve discrepancies among previous studies on the organ.
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Affiliation(s)
- Naoyuki Ohta
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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Tresser J, Chiba S, Veeman M, El-Nachef D, Newman-Smith E, Horie T, Tsuda M, Smith WC. doublesex/mab3 related-1 (dmrt1) is essential for development of anterior neural plate derivatives in Ciona. Development 2010; 137:2197-203. [PMID: 20530547 PMCID: PMC2882137 DOI: 10.1242/dev.045302] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2010] [Indexed: 12/17/2022]
Abstract
Ascidian larvae have a hollow, dorsal central nervous system that shares many morphological features with vertebrate nervous systems yet is composed of very few cells. We show here that a null mutation in the gene dmrt1 in the ascidian Ciona savignyi results in profound abnormalities in the development of the sensory vesicle (brain), as well as other anterior ectodermal derivatives, including the palps and oral siphon primordium (OSP). Although the phenotype of the mutant embryos is variable, the majority have a complete loss of the most anterior structures (palps and OSP) and extensive disruption of sensory structures, such as the light-sensitive ocellus, in the sensory vesicle. dmrt1 is expressed early in the blastula embryo in a small group of presumptive ectodermal cells as they become restricted to anterior neural, OSP and palp fates. Despite the early and restricted expression of dmrt1, we were unable, using several independent criteria, to observe a defect in the mutant embryos until the early tailbud stage. We speculate that the variability and late onset in the phenotype may be due to partially overlapping activities of other gene products.
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Affiliation(s)
- Jason Tresser
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Shota Chiba
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Michael Veeman
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Danny El-Nachef
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Erin Newman-Smith
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Takeo Horie
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Motoyuki Tsuda
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - William C. Smith
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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Horie T, Nakagawa M, Sasakura Y, Kusakabe TG, Tsuda M. Simple motor system of the ascidian larva: neuronal complex comprising putative cholinergic and GABAergic/glycinergic neurons. Zoolog Sci 2010; 27:181-90. [PMID: 20141423 DOI: 10.2108/zsj.27.181] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ascidian larva is an excellent model for studies of the functional organization and neuronal circuits of chordates due to its remarkably simple central nervous system (CNS), comprised of about 100 neurons. To date, however, the identities of the various neurons in the ascidian larva, particularly their neurotransmitter phenotypes, are not well established. Acetylcholine, GABA, and glycine are critical neurotransmitters for locomotion in many animals. We visualized putative cholinergic neurons and GABAergic/glycinergic neurons in the ascidian larva by immunofluorescent staining using antibodies against vesicular acetylcholine transporter (VACHT) and vesicular GABA/glycine transporter (VGAT), respectively. Neurons expressing a cholinergic phenotype were found in the brain vesicle and the visceral ganglion. Five pairs of VACHT-positive neurons were located in the visceral ganglion. These putative cholinergic neurons extended their axons posteriorly and formed nerve terminals proximal to the most anterior muscle cells in the tail. VGAT-positive neurons were located in the brain vesicle, the visceral ganglion, and the anterior nerve cord. Two distinct pairs of VGAT-positive neurons, bilaterally aligned along the anterior nerve cord, extended axons anteriorly, near to the axons of the contralateral VACHT-positive neurons. Cell bodies of the VGAT-positive neurons lay on these nerve tracts. The neuronal complex, comprising motor neurons with a cholinergic phenotype and some of the GABA/glycinergic interneurons, has structural features that are compatible with a central pattern generator (CPG) producing a rhythmic movement of the tail. The simple CPG of the ascidian larva may represent the ancestral state of the vertebrate motor system.
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Affiliation(s)
- Takeo Horie
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan.
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Shimozono N, Ohta N, Satoh N, Hamada M. Differential regional expression of genes in the developing brain of Ciona intestinalis embryos. Zoolog Sci 2010; 27:103-9. [PMID: 20141415 DOI: 10.2108/zsj.27.103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Our previous transcriptome analysis identified 565 genes that are preferentially expressed in the developing brain of Ciona intestinalis larvae. Here, we show by in-situ hybridization that the spatial expression patterns of these brain-specific genes fall into different categories depending on the regions where the gene is expressed. For example, Ci-opsin3 and Ci-Dkk3 are expressed in the entire brain, Ci-tyrosinase and Ci-TYRP1 in the dorsal region, and Ci-synaptotagmin3, Ci-ZF399, and Ci-PTFb in the ventral region. Other genes are specific to the posterior, anterior, central, posterior and ventral, or anterior-ventral region of the brain. This regional expression of genes in the Ciona brain is not always associated with cell lineage, suggesting that complex mechanisms control the regionalized expression of brain-specific genes.
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Affiliation(s)
- Naoki Shimozono
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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Takamura K, Minamida N, Okabe S. Neural Map of the Larval Central Nervous System in the AscidianCiona intestinalis. Zoolog Sci 2010; 27:191-203. [DOI: 10.2108/zsj.27.191] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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42
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Distribution and structural diversity of cilia in tadpole larvae of the ascidian Ciona intestinalis. Dev Biol 2010; 337:42-62. [DOI: 10.1016/j.ydbio.2009.10.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2009] [Revised: 09/22/2009] [Accepted: 10/03/2009] [Indexed: 12/27/2022]
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Abstract
Recent findings shed light on the steps underlying the evolution of vertebrate photoreceptors and retina. Vertebrate ciliary photoreceptors are not as wholly distinct from invertebrate rhabdomeric photoreceptors as is sometimes thought. Recent information on the phylogenies of ciliary and rhabdomeric opsins has helped in constructing the likely routes followed during evolution. Clues to the factors that led the early vertebrate retina to become invaginated can be obtained by combining recent knowledge about the origin of the pathway for dark re-isomerization of retinoids with knowledge of the inability of ciliary opsins to undergo photoreversal, along with consideration of the constraints imposed under the very low light levels in the deep ocean. Investigation of the origin of cell classes in the vertebrate retina provides support for the notion that cones, rods and bipolar cells all originated from a primordial ciliary photoreceptor, whereas ganglion cells, amacrine cells and horizontal cells all originated from rhabdomeric photoreceptors. Knowledge of the molecular differences between cones and rods, together with knowledge of the scotopic signalling pathway, provides an understanding of the evolution of rods and of the rods' retinal circuitry. Accordingly, it has been possible to propose a plausible scenario for the sequence of evolutionary steps that led to the emergence of vertebrate photoreceptors and retina.
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Affiliation(s)
- Trevor D Lamb
- ARC Centre of Excellence in Vision Science, The Australian National University, Canberra ACT 0200, Australia.
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44
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Larhammar D, Nordström K, Larsson TA. Evolution of vertebrate rod and cone phototransduction genes. Philos Trans R Soc Lond B Biol Sci 2009; 364:2867-80. [PMID: 19720650 DOI: 10.1098/rstb.2009.0077] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Vertebrate cones and rods in several cases use separate but related components for their signal transduction (opsins, G-proteins, ion channels, etc.). Some of these proteins are also used differentially in other cell types in the retina. Because cones, rods and other retinal cell types originated in early vertebrate evolution, it is of interest to see if their specific genes arose in the extensive gene duplications that took place in the ancestor of the jawed vertebrates (gnathostomes) by two tetraploidizations (genome doublings). The ancestor of teleost fishes subsequently underwent a third tetraploidization. Our previously reported analyses showed that several gene families in the vertebrate visual phototransduction cascade received new members in the basal tetraploidizations. We here expand these data with studies of additional gene families and vertebrate species. We conclude that no less than 10 of the 13 studied phototransduction gene families received additional members in the two basal vertebrate tetraploidizations. Also the remaining three families seem to have undergone duplications during the same time period but it is unclear if this happened as a result of the tetraploidizations. The implications of the many early vertebrate gene duplications for functional specialization of specific retinal cell types, particularly cones and rods, are discussed.
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Affiliation(s)
- Dan Larhammar
- Department of Neuroscience, Unit of Pharmacology, Uppsala University, SE-751 24 Uppsala, Sweden.
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Kusakabe TG, Takimoto N, Jin M, Tsuda M. Evolution and the origin of the visual retinoid cycle in vertebrates. Philos Trans R Soc Lond B Biol Sci 2009; 364:2897-910. [PMID: 19720652 PMCID: PMC2781855 DOI: 10.1098/rstb.2009.0043] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Absorption of a photon by visual pigments induces isomerization of 11-cis-retinaldehyde (RAL) chromophore to all-trans-RAL. Since the opsins lacking 11-cis-RAL lose light sensitivity, sustained vision requires continuous regeneration of 11-cis-RAL via the process called 'visual cycle'. Protostomes and vertebrates use essentially different machinery of visual pigment regeneration, and the origin and early evolution of the vertebrate visual cycle is an unsolved mystery. Here we compare visual retinoid cycles between different photoreceptors of vertebrates, including rods, cones and non-visual photoreceptors, as well as between vertebrates and invertebrates. The visual cycle systems in ascidians, the closest living relatives of vertebrates, show an intermediate state between vertebrates and non-chordate invertebrates. The ascidian larva may use retinochrome-like opsin as the major isomerase. The entire process of the visual cycle can occur inside the photoreceptor cells with distinct subcellular compartmentalization, although the visual cycle components are also present in surrounding non-photoreceptor cells. The adult ascidian probably uses RPE65 isomerase, and trans-to-cis isomerization may occur in distinct cellular compartments, which is similar to the vertebrate situation. The complete transition to the sophisticated retinoid cycle of vertebrates may have required acquisition of new genes, such as interphotoreceptor retinoid-binding protein, and functional evolution of the visual cycle genes.
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Affiliation(s)
- Takehiro G. Kusakabe
- Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan
| | - Noriko Takimoto
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan
| | - Minghao Jin
- Department of Ophthalmology and Neuroscience Center, LSU School of Medicine, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA
| | - Motoyuki Tsuda
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa 769-2193, Japan
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Horie T, Nakagawa M, Sasakura Y, Kusakabe TG. Cell type and function of neurons in the ascidian nervous system. Dev Growth Differ 2009; 51:207-20. [PMID: 19379276 DOI: 10.1111/j.1440-169x.2009.01105.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ascidians, or sea squirts, are primitive chordates, and their tadpole larvae share a basic body plan with vertebrates, including a notochord and a dorsal tubular central nervous system (CNS). The CNS of the ascidian larva is formed through a process similar to vertebrate neurulation, while the ascidian CNS is remarkably simple, consisting of about 100 neurons. Recent identification of genes that are specifically expressed in a particular subtype of neurons has enabled us to reveal neuronal networks at single-cell resolution. Based on the information on neuron subtype-specific genes, different populations of neurons have been visualized by whole-mount in situ hybridization, immunohistochemical staining using specific antibodies, and fluorescence labeling of cell bodies and neurites by a fluorescence protein reporter driven by neuron-specific promoters. Neuronal populations that have been successfully visualized include glutamatergic, cholinergic, gamma-aminobutyric acid/glycinergic, and dopaminergic neurons, which have allowed us to propose functional regionalization of the CNS and a neural circuit for locomotion. Thus, the simple nervous system of the ascidian larva can serve as an attractive model system for studying the development, function, and evolution of the chordate nervous system.
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Affiliation(s)
- Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan.
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