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Piekarz KM, Stolfi A. Development and circuitry of the tunicate larval Motor Ganglion, a putative hindbrain/spinal cord homolog. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART B, MOLECULAR AND DEVELOPMENTAL EVOLUTION 2024; 342:200-211. [PMID: 37675754 PMCID: PMC10918034 DOI: 10.1002/jez.b.23221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/13/2023] [Accepted: 08/22/2023] [Indexed: 09/08/2023]
Abstract
The Motor Ganglion (MG) is a small collection of neurons that control the swimming movements of the tunicate tadpole larva. Situated at the base of the tail, molecular and functional comparisons suggest that may be a homolog of the spinal cord and/or hindbrain ("rhombospinal" region) of vertebrates. Here we review the most current knowledge of the development, connectivity, functions, and unique identities of the neurons that comprise the MG, drawn mostly from studies in Ciona spp. The simple cell lineages, minimal cellular composition, and comprehensively mapped "connectome" of the Ciona MG all make this an excellent model for studying the development and physiology of motor control in aquatic larvae.
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Affiliation(s)
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology
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2
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Hoyer J, Kolar K, Athira A, van den Burgh M, Dondorp D, Liang Z, Chatzigeorgiou M. Polymodal sensory perception drives settlement and metamorphosis of Ciona larvae. Curr Biol 2024; 34:1168-1182.e7. [PMID: 38335959 DOI: 10.1016/j.cub.2024.01.041] [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: 07/23/2023] [Revised: 12/04/2023] [Accepted: 01/16/2024] [Indexed: 02/12/2024]
Abstract
The Earth's oceans brim with an incredible diversity of microscopic lifeforms, including motile planktonic larvae, whose survival critically depends on effective dispersal in the water column and subsequent exploration of the seafloor to identify a suitable settlement site. How their nervous systems mediate sensing of diverse multimodal cues remains enigmatic. Here, we uncover that the tunicate Ciona intestinalis larvae employ ectodermal sensory cells to sense various mechanical and chemical cues. Combining whole-brain imaging and chemogenetics, we demonstrate that stimuli encoded at the periphery are sufficient to drive global brain-state changes to promote or impede both larval attachment and metamorphosis behaviors. The ability of C. intestinalis larvae to leverage polymodal sensory perception to support information coding and chemotactile behaviors may explain how marine larvae make complex decisions despite streamlined nervous systems.
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Affiliation(s)
- Jorgen Hoyer
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Kushal Kolar
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Athira Athira
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Meike van den Burgh
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Daniel Dondorp
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Zonglai Liang
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway
| | - Marios Chatzigeorgiou
- Michael Sars Centre, Faculty of Mathematics and Natural Sciences, University of Bergen, Bergen 5006, Norway.
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3
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Satake H, Sasakura Y. The neuroendocrine system of Ciona intestinalis Type A, a deuterostome invertebrate and the closest relative of vertebrates. Mol Cell Endocrinol 2024; 582:112122. [PMID: 38109989 DOI: 10.1016/j.mce.2023.112122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/05/2023] [Accepted: 12/09/2023] [Indexed: 12/20/2023]
Abstract
Deuterostome invertebrates, including echinoderms, hemichordates, cephalochordates, and urochordates, exhibit common and species-specific morphological, developmental, physiological, and behavioral characteristics that are regulated by neuroendocrine and nervous systems. Over the past 15 years, omics, genetic, and/or physiological studies on deuterostome invertebrates have identified low-molecular-weight transmitters, neuropeptides and their cognate receptors, and have clarified their various biological functions. In particular, there has been increasing interest on the neuroendocrine and nervous systems of Ciona intestinalis Type A, which belongs to the subphylum Urochordata and occupies the critical phylogenetic position as the closest relative of vertebrates. During the developmental stage, gamma-aminobutylic acid, D-serine, and gonadotropin-releasing hormones regulate metamorphosis of Ciona. In adults, the neuropeptidergic mechanisms underlying ovarian follicle growth, oocyte maturation, and ovulation have been elucidated. This review article provides the most recent and fundamental knowledge of the neuroendocrine and nervous systems of Ciona, and their evolutionary aspects.
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Affiliation(s)
- Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto, Japan.
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
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4
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Utsumi MK, Oka K, Hotta K. Transitions of motor neuron activities during Ciona development. Front Cell Dev Biol 2023; 11:1100887. [PMID: 36711039 PMCID: PMC9880257 DOI: 10.3389/fcell.2023.1100887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/03/2023] [Indexed: 01/15/2023] Open
Abstract
Motor neurons (MNs) are one of the most important components of Central Pattern Generators (CPG) in vertebrates (Brown, Proceedings of The Royal Society B: Biological Sciences (The Royal Society), 1911, 84(572), 308-319). However, it is unclear how the neural activities of these components develop during their embryogenesis. Our previous study revealed that in Ciona robusta (Ciona intestinalis type A), a model organism with a simple neural circuit, a single pair of MNs (MN2L/MN2R) was determining the rhythm of its spontaneous early motor behavior (developmental stage St.22-24). MN2s are known to be one of the main components of Ciona CPG, though the neural activities of MN2s in the later larval period (St.25-) were not yet investigated. In this study, we investigated the neural activities of MN2s during their later stages and how they are related to Ciona's swimming CPG. Long-term simultaneous Ca2+ imaging of both MN2s with GCaMP6s/f (St.22-34) revealed that MN2s continued to determine the rhythm of motor behavior even in their later larval stages. Their activities were classified into seven phases (I-VII) depending on the interval and the synchronicity of MN2L and MN2R Ca2+ transients. Initially, each MN2 oscillates sporadically (I). As they develop into swimming larvae, they gradually oscillate at a constant interval (II-III), then start to synchronize (IV) and fully synchronize (V). Intervals become longer (VI) and sporadic again during the tail aggression period (VII). Interestingly, 76% of the embryos started to oscillate from MN2R. In addition, independent photostimulations on left and right MN2s were conducted. This is the first report of the live imaging of neural activities in Ciona's developing swimming CPG. These findings will help to understand the development of motor neuron circuits in chordate animals.
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Affiliation(s)
- Madoka K. Utsumi
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Kotaro Oka
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan,Waseda Research Institute for Science and Engineering, Waseda University, Shinjuku, Japan,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan,*Correspondence: Kohji Hotta,
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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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Zhang J, Dong B, Yang L. Molecular Characterization and Expression Analysis of Putative Class C (Glutamate Family) G Protein-Coupled Receptors in Ascidian Styela clava. BIOLOGY 2022; 11:782. [PMID: 35625509 PMCID: PMC9138782 DOI: 10.3390/biology11050782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
In this study, we performed the genome-wide domain analysis and sequence alignment on the genome of Styela clava, and obtained a repertoire of 204 putative GPCRs, which exhibited a highly reduced gene number compared to vertebrates and cephalochordates. In this repertoire, six Class C GPCRs, including four metabotropic glutamate receptors (Sc-GRMs), one calcium-sensing receptor (Sc-CaSR), and one gamma-aminobutyric acid (GABA) type B receptor 2-like (Sc-GABABR2-like) were identified, with the absence of type 1 taste and vomeronasal receptors. All the Sc-GRMs and Sc-CaSR contained the typical "Venus flytrap" and cysteine-rich domains required for ligand binding and subsequent propagation of conformational changes. In swimming larvae, Sc-grm3 and Sc-casr were mainly expressed at the junction of the sensory vesicle and tail nerve cord while the transcripts of Sc-grm4, Sc-grm7a, and Sc-grm7b appeared at the anterior trunk, which suggested their important functions in neurotransmission. The high expression of these Class C receptors at tail-regression and metamorphic juvenile stages hinted at their potential involvement in regulating metamorphosis. In adults, the transcripts were highly expressed in several peripheral tissues, raising the possibility that S. clava Class C GPCRs might function as neurotransmission modulators peripherally after metamorphosis. Our study systematically characterized the ancestral chordate Class C GPCRs to provide insights into the origin and evolution of these receptors in chordates and their roles in regulating physiological and morphogenetic changes relevant to the development and environmental adaption.
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Affiliation(s)
- Jin Zhang
- Sars-Fang Centre, MoE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China;
| | - Bo Dong
- Sars-Fang Centre, MoE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China;
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
- Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao 266003, China
| | - Likun Yang
- Sars-Fang Centre, MoE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China;
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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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Akahoshi T, Utsumi MK, Oonuma K, Murakami M, Horie T, Kusakabe TG, Oka K, Hotta K. A single motor neuron determines the rhythm of early motor behavior in Ciona. SCIENCE ADVANCES 2021; 7:eabl6053. [PMID: 34890229 PMCID: PMC8664258 DOI: 10.1126/sciadv.abl6053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/21/2021] [Indexed: 05/25/2023]
Abstract
Recent work in tunicate supports the similarity between the motor circuits of vertebrates and basal deuterostome lineages. To understand how the rhythmic activity in motor circuits is acquired during development of protochordate Ciona, we investigated the coordination of the motor response by identifying a single pair of oscillatory motor neurons (MN2/A10.64). The MN2 neurons had Ca2+ oscillation with an ~80-s interval that was cell autonomous even in a dissociated single cell. The Ca2+ oscillation of MN2 coincided with the early tail flick (ETF). The spikes of the membrane potential in MN2 gradually correlated with the rhythm of ipsilateral muscle contractions in ETFs. The optogenetic experiments indicated that MN2 is a necessary and sufficient component of ETFs. These results indicate that MN2 is indispensable for the early spontaneous rhythmic motor behavior of Ciona. Our findings shed light on the understanding of development and evolution of chordate rhythmical locomotion.
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Affiliation(s)
- Taichi Akahoshi
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kohoku, Yokohama 223-8522, Japan
| | - Madoka K. Utsumi
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kohoku, Yokohama 223-8522, Japan
| | - Kouhei Oonuma
- Institute for Integrative Neurobiology and Department of Biology, Konan University, Kobe 658-8501, Japan
| | - Makoto Murakami
- Institute for Integrative Neurobiology and Department of Biology, Konan University, Kobe 658-8501, Japan
| | - Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, Shimoda 415-0025, Japan
| | - Takehiro G. Kusakabe
- Institute for Integrative Neurobiology and Department of Biology, Konan University, Kobe 658-8501, Japan
| | - Kotaro Oka
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kohoku, Yokohama 223-8522, Japan
| | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Kohoku, Yokohama 223-8522, Japan
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9
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Fodor ACA, Powers MM, Andrykovich K, Liu J, Lowe EK, Brown CT, Di Gregorio A, Stolfi A, Swalla BJ. The Degenerate Tale of Ascidian Tails. Integr Comp Biol 2021; 61:358-369. [PMID: 33881514 PMCID: PMC10452958 DOI: 10.1093/icb/icab022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ascidians are invertebrate chordates, with swimming chordate tadpole larvae that have distinct heads and tails. The head contains the small brain, sensory organs, including the ocellus (light) and otolith (gravity) and the presumptive endoderm, while the tail has a notochord surrounded by muscle cells and a dorsal nerve cord. One of the chordate features is a post-anal tail. Ascidian tadpoles are nonfeeding, and their tails are critical for larval locomotion. After hatching the larvae swim up toward light and are carried by the tide and ocean currents. When competent to settle, ascidian tadpole larvae swim down, away from light, to settle and metamorphose into a sessile adult. Tunicates are classified as chordates because of their chordate tadpole larvae; in contrast, the sessile adult has a U-shaped gut and very derived body plan, looking nothing like a chordate. There is one group of ascidians, the Molgulidae, where many species are known to have tailless larvae. The Swalla Lab has been studying the evolution of tailless ascidian larvae in this clade for over 30 years and has shown that tailless larvae have evolved independently several times in this clade. Comparison of the genomes of two closely related species, the tailed Molgula oculata and tailless Molgula occulta reveals much synteny, but there have been multiple insertions and deletions that have disrupted larval genes in the tailless species. Genomics and transcriptomics have previously shown that there are pseudogenes expressed in the tailless embryos, suggesting that the partial rescue of tailed features in their hybrid larvae is due to the expression of intact genes from the tailed parent. Yet surprisingly, we find that the notochord gene regulatory network is mostly intact in the tailless M. occulta, although the notochord does not converge and extend and remains as an aggregate of cells we call the "notoball." We expect that eventually many of the larval gene networks will become evolutionarily lost in tailless ascidians and the larval body plan abandoned, with eggs developing directly into an adult. Here we review the current evolutionary and developmental evidence on how the molgulids lost their tails.
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Affiliation(s)
- Alexander C A Fodor
- Biology Department, University of Washington, Seattle, WA 98195, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - Megan M Powers
- Biology Department, University of Washington, Seattle, WA 98195, USA
| | - Kristin Andrykovich
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - Jiatai Liu
- Biology Department, University of Washington, Seattle, WA 98195, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
| | - Elijah K Lowe
- Biology Department, University of Washington, Seattle, WA 98195, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Station Biologique de Roscoff, 29680 Roscoff, France
| | - C Titus Brown
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Station Biologique de Roscoff, 29680 Roscoff, France
- Population Health and Reproduction, UC Davis School of Veterinary Medicine, Davis, CA 95616, USA
| | - Anna Di Gregorio
- Department of Molecular Pathobiology, NYU College of Dentistry, New York, NY 10010, USA
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
- Station Biologique de Roscoff, 29680 Roscoff, France
| | - Billie J Swalla
- Biology Department, University of Washington, Seattle, WA 98195, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA 98250, USA
- Station Biologique de Roscoff, 29680 Roscoff, France
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10
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Hudson C, Yasuo H. Neuromesodermal Lineage Contribution to CNS Development in Invertebrate and Vertebrate Chordates. Genes (Basel) 2021; 12:genes12040592. [PMID: 33920662 PMCID: PMC8073528 DOI: 10.3390/genes12040592] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/12/2022] Open
Abstract
Ascidians are invertebrate chordates and the closest living relative to vertebrates. In ascidian embryos a large part of the central nervous system arises from cells associated with mesoderm rather than ectoderm lineages. This seems at odds with the traditional view of vertebrate nervous system development which was thought to be induced from ectoderm cells, initially with anterior character and later transformed by posteriorizing signals, to generate the entire anterior-posterior axis of the central nervous system. Recent advances in vertebrate developmental biology, however, show that much of the posterior central nervous system, or spinal cord, in fact arises from cells that share a common origin with mesoderm. This indicates a conserved role for bi-potential neuromesoderm precursors in chordate CNS formation. However, the boundary between neural tissue arising from these distinct neural lineages does not appear to be fixed, which leads to the notion that anterior-posterior patterning and neural fate formation can evolve independently.
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11
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Pirtle TJ, Satterlie RA. Cyclic Guanosine Monophosphate Modulates Locomotor Acceleration Induced by Nitric Oxide but not Serotonin in Clione limacina Central Pattern Generator Swim Interneurons. Integr Org Biol 2021; 3:obaa045. [PMID: 33791588 PMCID: PMC7884873 DOI: 10.1093/iob/obaa045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Both nitric oxide (NO) and serotonin (5HT) mediate swim acceleration in the marine mollusk, Clione limacina. In this study, we examine the role that the second messenger, cyclic guanosine monophosphate (cGMP), plays in mediating NO and 5HT-induced swim acceleration. We observed that the application of an analog of cGMP or an activator of soluble guanylyl cyclase (sGC) increased fictive locomotor speed recorded from Pd-7 interneurons of the animal's locomotor central pattern generator. Moreover, inhibition of sGC decreased fictive locomotor speed. These results suggest that basal levels of cGMP are important for slow swimming and that increased production of cGMP mediates swim acceleration in Clione. Because NO has its effect through cGMP signaling and because we show herein that cGMP produces cellular changes in Clione swim interneurons that are consistent with cellular changes produced by 5HT application, we hypothesize that both NO and 5HT function via a common signal transduction pathway that involves cGMP. Our results show that cGMP mediates NO-induced but not 5HT-induced swim acceleration in Clione.
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Affiliation(s)
- Thomas J Pirtle
- Department of Biology, The College of Idaho, 2112 Cleveland Blvd Caldwell, ID 83605, USA
| | - Richard A Satterlie
- Department of Biology and Marine Biology and Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin K. Moss Road, Wilmington, NC 28409, USA
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12
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Eliso MC, Bergami E, Manfra L, Spagnuolo A, Corsi I. Toxicity of nanoplastics during the embryogenesis of the ascidian Ciona robusta (Phylum Chordata). Nanotoxicology 2020; 14:1415-1431. [PMID: 33186509 DOI: 10.1080/17435390.2020.1838650] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Nanoplastics are considered contaminants of emerging concern at the global scale. The recent evidence of their occurrence in seawater from the Mediterranean Sea calls for a thorough evaluation of their impact on marine life and in particular on vulnerable life stages such as planktonic embryos. Here, we investigated the impact of increasing nominal concentrations of 50 nm amino-modified (PS-NH2) and 60 nm carboxy-modified (PS-COOH) polystyrene nanoparticles (PS NPs) on the embryonic development of the ascidian Ciona robusta (phylum Chordata), a common benthic invertebrate living in Mediterranean coastal areas with the peculiarity of being an early chordate developmental model. A strong agglomeration of PS-COOH (approx. 1 µm) was observed in natural sea water (NSW) already at time 0, while PS-NH2 resulted still monodispersed (approx. 130 nm) but largely aggregated after 22 h with a microscale dimension similar to those negatively charged. However, their effect on C. robusta embryos development largely differed at 22 h: PS-COOH did not affect larvae phenotypes nor their development, while PS-NH2 caused a dose-dependent effect (EC50 (22 h) of 7.52 μg mL-1) with various degrees of phenotype malformations (from mild to severe) and impairment of larval swimming. Embryos (up to 30%) exposed to 15 µg mL-1 PS-NH2 resulted not developed and the majority was unable to hatch. Calculated PS-NH2 EC50 resulted higher than those available for other marine invertebrate species, suggesting a protective role of the egg envelopes surrounding C. robusta embryos toward nanoplastics exposure.
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Affiliation(s)
- Maria Concetta Eliso
- Department of Physical, Earth and Environmental Sciences, University of Siena, Siena, Italy.,Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Elisa Bergami
- Department of Physical, Earth and Environmental Sciences, University of Siena, Siena, Italy
| | - Loredana Manfra
- Department of Marine Biotechnology, Stazione Zoologica Anton Dohrn, Naples, Italy.,Institute for Environmental Protection and Research (ISPRA), Rome, Italy
| | - Antonietta Spagnuolo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Ilaria Corsi
- Department of Physical, Earth and Environmental Sciences, University of Siena, Siena, Italy
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13
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Cellular identity and Ca 2+ signaling activity of the non-reproductive GnRH system in the Ciona intestinalis type A (Ciona robusta) larva. Sci Rep 2020; 10:18590. [PMID: 33122709 PMCID: PMC7596717 DOI: 10.1038/s41598-020-75344-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
Tunicate larvae have a non-reproductive gonadotropin-releasing hormone (GnRH) system with multiple ligands and receptor heterodimerization enabling complex regulation. In Ciona intestinalis type A larvae, one of the gnrh genes, gnrh2, is conspicuously expressed in the motor ganglion and nerve cord, which are homologous structures to the hindbrain and spinal cord, respectively, of vertebrates. The gnrh2 gene is also expressed in the proto-placodal sensory neurons, which are the proposed homologue of vertebrate olfactory neurons. Tunicate larvae occupy a non-reproductive dispersal stage, yet the role of their GnRH system remains elusive. In this study, we investigated neuronal types of gnrh2-expressing cells in Ciona larvae and visualized the activity of these cells by fluorescence imaging using a calcium sensor protein. Some cholinergic neurons and dopaminergic cells express gnrh2, suggesting that GnRH plays a role in controlling swimming behavior. However, none of the gnrh2-expressing cells overlap with glycinergic or GABAergic neurons. A role in motor control is also suggested by a relationship between the activity of gnrh2-expressing cells and tail movements. Interestingly, gnrh2-positive ependymal cells in the nerve cord, known as a kind of glia cells, actively produced Ca2+ transients, suggesting that active intercellular signaling occurs in the glia cells of the nerve cord.
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Transphyletic conservation of nitric oxide synthase regulation in cephalochordates and tunicates. Dev Genes Evol 2020; 230:329-338. [PMID: 32839880 DOI: 10.1007/s00427-020-00668-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 08/16/2020] [Indexed: 12/19/2022]
Abstract
Nitric oxide synthase is ubiquitously present in metazoans and is involved in a wide range of biological processes. Three distinct Nos genes have been so far identified in vertebrates exhibiting a complex expression pattern and transcriptional regulation. Nevertheless, although independent events of Nos duplication have been observed in several taxa, only few studies described the regulatory mechanisms responsible for their activation in non-vertebrate animals. To shed light on the mechanisms underlying neuronal-type Nos expression, we focused on two non-vertebrate chordates: the cephalochordate Branchiostoma lanceolatum and the tunicate Ciona robusta. Here, throughout transphyletic and transgenic approaches, we identified genomic regions in both species acting as Nos functional enhancers during development. In vivo analyses of Nos genomic fragments revealed their ability to recapitulate the endogenous expression territories. Therefore, our results suggest the existence of evolutionary conserved mechanisms responsible for neuronal-type Nos regulation in non-vertebrate chordates. In conclusion, this study paves the way for future characterization of conserved transcriptional logic underlying the expression of neuronal-type Nos genes in chordates.
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Hozumi A, Matsunobu S, Mita K, Treen N, Sugihara T, Horie T, Sakuma T, Yamamoto T, Shiraishi A, Hamada M, Satoh N, Sakurai K, Satake H, Sasakura Y. GABA-Induced GnRH Release Triggers Chordate Metamorphosis. Curr Biol 2020; 30:1555-1561.e4. [PMID: 32220316 DOI: 10.1016/j.cub.2020.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 12/14/2019] [Accepted: 02/03/2020] [Indexed: 01/13/2023]
Abstract
Metamorphosis, a widespread life history strategy in metazoans, allows dispersal and use of different ecological niches through a dramatic body change from a larval stage [1, 2]. Despite its conservation and importance, the molecular mechanisms underlying its initiation and progression have been characterized in only a few animal models. In this study, through pharmacological and gene functional analyses, we identified neurotransmitters responsible for metamorphosis of the ascidian Ciona. Ciona metamorphosis converts swimming tadpole larvae into vase-like, sessile adults. Here, we show that the neurotransmitter GABA is a key regulator of metamorphosis. We found that gonadotropin-releasing hormone (GnRH) is a downstream neuropeptide of GABA. Although GABA is generally thought of as an inhibitory neurotransmitter, we found that it positively regulates secretion of GnRH through the metabotropic GABA receptor during Ciona metamorphosis. GnRH is necessary for reproductive maturation in vertebrates, and GABA is an important excitatory regulator of GnRH in the hypothalamus during puberty [3, 4]. Our findings reveal another role of the GABA-GnRH axis in the regulation of post-embryonic development in chordates.
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Affiliation(s)
- Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Shohei Matsunobu
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Kaoru Mita
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Nicholas Treen
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Takaho Sugihara
- Department of Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan
| | - Tetsushi Sakuma
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8526, Japan
| | - Takashi Yamamoto
- Division of Integrated Sciences for Life, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8526, Japan
| | - Akira Shiraishi
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto 619-0284, Japan
| | - Mayuko Hamada
- Ushimado Marine Institute, Okayama University, Okayama 701-4303, Japan
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa 904-0495, Japan
| | - Keisuke Sakurai
- Department of Biology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki 305-8572, Japan
| | - Honoo Satake
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Kyoto 619-0284, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka 415-0025, Japan.
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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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Hirai S, Hotta K, Okado H. Developmental Roles and Evolutionary Significance of AMPA-Type Glutamate Receptors. Bioessays 2018; 40:e1800028. [PMID: 30058076 DOI: 10.1002/bies.201800028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 07/02/2018] [Indexed: 11/07/2022]
Abstract
Organogenesis and metamorphosis require the intricate orchestration of multiple types of cellular interactions and signaling pathways. Glutamate (Glu) is an excitatory extracellular signaling molecule in the nervous system, while Ca2+ is a major intracellular signaling molecule. The first Glu receptors to be cloned are Ca2+ -permeable receptors in mammalian brains. Although recent studies have focused on Glu signaling in synaptic mechanisms of the mammalian central nervous system, it is unclear how this signaling functions in development. Our recent article demonstrated that Ca2+ -permeable AMPA-type Glu receptors (GluAs) are essential for formation of a photosensitive organ, development of some neurons, and metamorphosis, including tail absorption and body axis rotation, in ascidian embryos. Based on findings in these embryos and mammalian brains, we formed several hypotheses regarding the evolution of GluAs, the non-synaptic function of Glu, the origin of GluA-positive neurons, and the neuronal network that controls metamorphosis in ascidians.
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Affiliation(s)
- Shinobu Hirai
- Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-0057, Japan
| | - Kohji Hotta
- Faculty of Science and Technology, Department of Biosciences and Informatics, Keio University, Kohoku, Yokohama, 223-8522, Japan
| | - Haruo Okado
- Department of Brain Development and Neural Regeneration, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo 156-0057, Japan
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18
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Sasakura Y. Cellulose production and the evolution of the sessile lifestyle in ascidians. ACTA ACUST UNITED AC 2018. [DOI: 10.4282/sosj.35.21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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19
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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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20
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Shimai K, Kusakabe TG. The Use of cis-Regulatory DNAs as Molecular Tools. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [DOI: 10.1007/978-981-10-7545-2_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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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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Ryan K, Lu Z, Meinertzhagen IA. The peripheral nervous system of the ascidian tadpole larva: Types of neurons and their synaptic networks. J Comp Neurol 2017; 526:583-608. [PMID: 29124768 DOI: 10.1002/cne.24353] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 01/01/2023]
Abstract
Physical and chemical cues from the environment are used to direct animal behavior through a complex network of connections originating in exteroceptors. In chordates, mechanosensory and chemosensory neurons of the peripheral nervous system (PNS) must signal to the motor circuits of the central nervous system (CNS) through a series of pathways that integrate and regulate the output to motor neurons (MN); ultimately these drive contraction of the tail and limb muscles. We used serial-section electron microscopy to reconstruct PNS neurons and their hitherto unknown synaptic networks in the tadpole larva of a sibling chordate, the ascidian, Ciona intestinalis. The larva has groups of neurons in its apical papillae, epidermal neurons in the rostral and apical trunk, caudal neurons in the dorsal and ventral epidermis, and a single tail tip neuron. The connectome reveals that the PNS input arises from scattered groups of these epidermal neurons, 54 in total, and has three main centers of integration in the CNS: in the anterior brain vesicle (which additionally receives input from photoreceptors of the ocellus), the motor ganglion (which contains five pairs of MN), and the tail, all of which in turn are themselves interconnected through important functional relay neurons. Some neurons have long collaterals that form autapses. Our study reveals interconnections with other sensory systems, and the exact inputs to the motor system required to regulate contractions in the tail that underlie larval swimming, or to the CNS to regulate substrate preference prior to the induction of larval settlement and metamorphosis.
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Affiliation(s)
- Kerrianne Ryan
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Zhiyuan Lu
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, Nova Scotia, Canada
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23
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Akahoshi T, Hotta K, Oka K. Characterization of calcium transients during early embryogenesis in ascidians Ciona robusta (Ciona intestinalis type A) and Ciona savignyi. Dev Biol 2017; 431:205-214. [PMID: 28935526 DOI: 10.1016/j.ydbio.2017.09.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/15/2017] [Accepted: 09/16/2017] [Indexed: 11/26/2022]
Abstract
The calcium ion (Ca2+) is an important second messenger, and a rapid increase in Ca2+ level (Ca2+ transient) is involved in various aspects of embryogenesis. Although Ca2+ transients play an important role in early developmental stages, little is known about their dynamics throughout embryogenesis. Here, Ca2+ transients were characterized by visualizing Ca2+ dynamics in developing chordate embryos using a fluorescent protein-based Ca2+ indicator, GCaMP6s in combination with finely tuned microscopy. Ca2+ transients were detected in precursors of muscle cells in the late gastrula stage. In the neurula stage, repetitive Ca2+ transients were observed in left and right neurogenic cells, including visceral ganglion (VG) precursors, and the duration of Ca2+ transients was 39±4s. In the early tailbud stage, Ca2+ transients were observed in differentiating precursors of nerve cord neurons. A small population of VG precursors showed rhythmical Ca2+ transients with a duration of 22±4s, suggesting a central pattern generator (CPG) origin. At the mid tailbud stage, Ca2+transients were observed in a wide area of epidermal cells and named CTECs. The number and frequency of CTECs increased drastically in late tailbud stages, and the timing of the increase coincided with that of the relaxation of the tail bending. The experiment using Ca2+ chelator showed that the CTECs were largely depending on the extracellular Ca2+. The waveform analysis of Ca2+ transients revealed different features according to duration and frequency. The comprehensive characterization of Ca2+ transients during early ascidian embryogenesis will help our understanding of the role of Ca2+ signaling in chordate embryogenesis.
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Affiliation(s)
- Taichi Akahoshi
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - Kohji Hotta
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
| | - Kotaro Oka
- Department of Bioscience and Informatics, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan
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24
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Sasakura Y, Hozumi A. Formation of adult organs through metamorphosis in ascidians. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2017; 7. [PMID: 29105358 DOI: 10.1002/wdev.304] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/28/2017] [Accepted: 09/11/2017] [Indexed: 02/05/2023]
Abstract
The representative characteristic of ascidians is their vertebrate-like, tadpole shape at the larval stage. Ascidians lose the tadpole shape through metamorphosis to become adults with a nonmotile, sessile body and a shape generally considered distinct from that of vertebrates. Solitary ascidians including Ciona species are extensively studied to understand the developmental mechanisms of ascidians, and to compare these mechanisms with their counterparts in vertebrates. In these ascidian species, the digestive and circulatory systems are not well developed in the larval trunk and the larvae do not take food. This is in contrast with the inner conditions of vertebrate tadpoles, which have functional organs comparable to those of adults. The adult organs and tissues of these ascidians become functional during metamorphosis that is completed quickly, suggesting that the ascidian larvae of solitary species are a transient stage of development. We here discuss how the cells and tissues in the ascidian larval body are converted into those of adults. The hearts of ascidians and vertebrates use closely related cellular and molecular mechanisms that suggest their shared origin. Hox genes of ascidians are essential for forming adult endodermal structures. To fully understand the development and evolution of chordates, a complete elucidation of the mechanisms underlying the adult tissue/organ formation of ascidians will be needed. WIREs Dev Biol 2018, 7:e304. doi: 10.1002/wdev.304 This article is categorized under: Comparative Development and Evolution > Body Plan Evolution Early Embryonic Development > Development to the Basic Body Plan.
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Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
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Ryan K, Lu Z, Meinertzhagen IA. Circuit Homology between Decussating Pathways in the Ciona Larval CNS and the Vertebrate Startle-Response Pathway. Curr Biol 2017; 27:721-728. [PMID: 28216318 DOI: 10.1016/j.cub.2017.01.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 12/22/2016] [Accepted: 01/13/2017] [Indexed: 10/20/2022]
Abstract
Comparing synaptic circuits and networks between brains of different animal groups helps us derive an understanding of how nervous systems might have evolved. The circuits of the startle response pathway in the brains of tailed vertebrates are known from electrophysiological studies on the giant reticulospinal Mauthner cells (M-cells). To identify morphological counterparts in chordate tunicates, a sister group of vertebrates [1, 2], we have compiled a densely reconstructed connectome (defined in [3]) for the CNS in the tadpole larva of Ciona intestinalis (L.), using ssEM [4]. The dorsal, tubular CNS of the ∼1-mm tadpole larva is built on a similar plan to vertebrates, its neurons distributed rostrocaudally in three centers, a brain vesicle, motor ganglion, and caudal nerve cord [5]. A single pair of descending decussating neurons, ddNs, found in the motor ganglion, have similarities to reticulospinal neurons descending from the vertebrate hindbrain to the spinal cord. The pre- and postsynaptic connections and circuits of these ddNs support their homology with decussating vertebrate M-cells. Network analysis reveals that, like M-cells, ddNs receive mechanosensory input from the peripheral nervous system and provide input to motoneurons, premotor interneurons, and ascending commissural inhibitory neurons (ACINs). These circuits uncover a putative homologous startle network in the Ciona tadpole. However, differences in circuits, including a lack of bilateral symmetry in their network, and convergence of inputs from left and right sides, raise questions about the relationship between form and function, and are a possible outcome of the tiny number of neurons in ascidian larvae.
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Affiliation(s)
- Kerrianne Ryan
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada; Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada.
| | - Zhiyuan Lu
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Ian A Meinertzhagen
- Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada; Department of Biology, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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26
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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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27
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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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28
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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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Hozumi A, Horie T, Sasakura Y. Neuronal map reveals the highly regionalized pattern of the juvenile central nervous system of the ascidian Ciona intestinalis. Dev Dyn 2015; 244:1375-93. [PMID: 26250096 DOI: 10.1002/dvdy.24317] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 07/28/2015] [Accepted: 08/02/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The dorsally located central nervous system (CNS) is an important hallmark of chordates. Among chordates, tunicate ascidians change their CNS remarkably by means of a metamorphosis from a highly regionalized larval CNS to an oval-shaped juvenile CNS without prominent morphological features. The neuronal organization of the CNS of ascidian tadpole larvae has been well described, but that in the CNS of postmetamorphosis juveniles has not been characterized well. RESULTS We investigated the number of neural cells, the number and position of differentiated neurons, and their axonal trajectories in the juvenile CNS of the ascidian Ciona intestinalis. The cell bodies of cholinergic, glutamatergic, and GABAergic/glycinergic neurons exhibited different localization patterns along the anterior-posterior axis in the juvenile CNS. Cholinergic neurons extended their axons toward the oral, atrial and body wall muscles and pharyngeal gill to regulate muscle contraction and ciliary movement. CONCLUSIONS Unlike its featureless shape, the juvenile CNS is highly patterned along the anterior-posterior axis. This patterning may be necessary for exerting multiple roles in the regulation of adult tissues distributed throughout the body. This basic information of the juvenile CNS of Ciona will allow in-depth studies of molecular mechanisms underlying the reconstruction of the CNS during ascidian metamorphosis.
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Affiliation(s)
- Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
| | - Takeo Horie
- Japan Science and Technology Agency, PRESTO, Honcho, Kawaguchi, Saitama, Japan
| | - Yasunori Sasakura
- Shimoda Marine Research Center, University of Tsukuba, Shimoda, Shizuoka, Japan
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Mikhaleva Y, Kreneisz O, Olsen LC, Glover JC, Chourrout D. Modification of the larval swimming behavior inOikopleura dioica, a chordate with a miniaturized central nervous system by dsRNA injection into fertilized eggs. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2015; 324:114-27. [DOI: 10.1002/jez.b.22607] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 10/27/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Yana Mikhaleva
- Sars International Centre for Marine Molecular Biology; University of Bergen; Norway
| | - Orsolya Kreneisz
- Sars International Centre for Marine Molecular Biology; University of Bergen; Norway
- Institute of Basic Medical Sciences; Faculty of Medicine; Department of Physiology; University of Oslo; Norway
| | - Lisbeth C. Olsen
- Sars International Centre for Marine Molecular Biology; University of Bergen; Norway
| | - Joel C. Glover
- Sars International Centre for Marine Molecular Biology; University of Bergen; Norway
- Institute of Basic Medical Sciences; Faculty of Medicine; Department of Physiology; University of Oslo; Norway
| | - Daniel Chourrout
- Sars International Centre for Marine Molecular Biology; University of Bergen; Norway
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Stolfi A, Gandhi S, Salek F, Christiaen L. Tissue-specific genome editing in Ciona embryos by CRISPR/Cas9. Development 2014; 141:4115-20. [PMID: 25336740 DOI: 10.1242/dev.114488] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The CRISPR/Cas9 system has ushered in a new era of targeted genetic manipulations. Here, we report the use of CRISPR/Cas9 to induce double-stranded breaks in the genome of the sea squirt Ciona intestinalis. We use electroporation to deliver CRISPR/Cas9 components for tissue-specific disruption of the Ebf (Collier/Olf/EBF) gene in hundreds of synchronized Ciona embryos. Phenotyping of transfected embryos in the 'F0' generation revealed that endogenous Ebf function is required for specification of Islet-expressing motor ganglion neurons and atrial siphon muscles. We demonstrate that CRISPR/Cas9 is sufficiently effective and specific to generate large numbers of embryos carrying mutations in a targeted gene of interest, which should allow for rapid screening of gene function in Ciona.
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Affiliation(s)
- Alberto Stolfi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Shashank Gandhi
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Farhana Salek
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003, USA
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Haupaix N, Stolfi A, Sirour C, Picco V, Levine M, Christiaen L, Yasuo H. p120RasGAP mediates ephrin/Eph-dependent attenuation of FGF/ERK signals during cell fate specification in ascidian embryos. Development 2013; 140:4347-52. [PMID: 24067356 DOI: 10.1242/dev.098756] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
ERK1/2 MAP kinase exhibits a highly dynamic activation pattern in developing embryos, which largely depends on fibroblast growth factor (FGF) signals. In ascidian embryos, FGF-dependent activation of ERK1/2 occurs differentially between sister cells during marginal zone and neural lineage patterning. Selective attenuation of FGF signals by localised ephrin/Eph signals accounts for this differential ERK activation, which controls the binary fate choice of each sibling cell pair. Here, we show that p120 Ras GTPase-activating protein (p120RasGAP) is a crucial mediator of these ephrin/Eph signals. First, inhibition of p120RasGAP has a similar effect to inhibition of ephrin/Eph function during marginal zone and neural patterning. Second, p120RasGAP acts epistatically to ephrin/Eph signals. Third, p120RasGAP physically associates with Eph3 in an ephrin-dependent manner. This study provides the first in vivo evidence that the functional association between Eph and RasGAP controls the spatial extent of FGF-activated ERK.
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Affiliation(s)
- Nicolas Haupaix
- Université Pierre et Marie Curie and Centre National de la Recherche Scientifique, Laboratoire de Biologie du Développement de Villefranche-sur-Mer, Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
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Matsushima A, Ryan K, Shimohigashi Y, Meinertzhagen IA. An endocrine disruptor, bisphenol A, affects development in the protochordate Ciona intestinalis: hatching rates and swimming behavior alter in a dose-dependent manner. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2013; 173:257-263. [PMID: 23207495 DOI: 10.1016/j.envpol.2012.10.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Revised: 10/04/2012] [Accepted: 10/10/2012] [Indexed: 05/20/2023]
Abstract
Bisphenol A (BPA) is widely used industrially to produce polycarbonate plastics and epoxy resins. Numerous studies document the harmful effects caused by low-dose BPA exposure especially on nervous systems and behavior in experimental animals such as mice and rats. Here, we exposed embryos of a model chordate, Ciona intestinalis, to seawater containing BPA to evaluate adverse effects on embryonic development and on the swimming behavior of subsequent larvae. Ciona is ideal because its larva develops rapidly and has few cells. The rate of larval hatching decreased in a dose-dependent manner with exposures to BPA above 3 μM; swimming behavior was also affected in larvae emerging from embryos exposed to 1 μM BPA. Adverse effects were most severe on fertilized eggs exposed to BPA within 7 h post-fertilization. Ciona shares twelve nuclear receptors with mammals, and BPA is proposed to disturb the physiological functions of one or more of these.
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Affiliation(s)
- Ayami Matsushima
- Laboratory of Structure-Function Biochemistry, Department of Chemistry, Faculty and Graduate School of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
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Hackley C, Mulholland E, Kim GJ, Newman-Smith E, Smith WC. A transiently expressed connexin is essential for anterior neural plate development in Ciona intestinalis. Development 2012; 140:147-55. [PMID: 23175630 DOI: 10.1242/dev.084681] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A forward genetic screen in the ascidian Ciona intestinalis identified a mutant line (frimousse) with a profound disruption in neural plate development. In embryos with the frimousse mutation, the anteriormost neural plate cells, which are products of an FGF induction at the blastula and gastrula stages, initially express neural plate-specific genes but fail to maintain the induced state and ultimately default to epidermis. The genetic lesion in the frimousse mutant lies within a connexin gene (cx-11) that is transiently expressed in the developing neural plate in a temporal window corresponding to the period of a-lineage neural induction. Using a genetically encoded calcium indicator we observed multiple calcium transients throughout the developing neural plate in wild-type embryos, but not in mutant embryos. A series of treatments at the gastrula and neurula stages that block the calcium transients, including gap junction inhibition and calcium depletion, were also found to disrupt the development of the anterior neural plate in a similar way to the frimousse mutation. The requirement for cx-11 for anterior neural fate points to a crucial role for intercellular communication via gap junctions, probably through mediation of Ca(2+) transients, in Ciona intestinalis neural induction.
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Affiliation(s)
- Christopher Hackley
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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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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Siboni N, Abrego D, Seneca F, Motti CA, Andreakis N, Tebben J, Blackall LL, Harder T. Using bacterial extract along with differential gene expression in Acropora millepora larvae to decouple the processes of attachment and metamorphosis. PLoS One 2012; 7:e37774. [PMID: 22655067 PMCID: PMC3359992 DOI: 10.1371/journal.pone.0037774] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 04/24/2012] [Indexed: 02/06/2023] Open
Abstract
Biofilms of the bacterium Pseudoalteromonas induce metamorphosis of acroporid coral larvae. The bacterial metabolite tetrabromopyrrole (TBP), isolated from an extract of Pseudoalteromonas sp. associated with the crustose coralline alga (CCA) Neogoniolithon fosliei, induced coral larval metamorphosis (100%) with little or no attachment (0–2%). To better understand the molecular events and mechanisms underpinning the induction of Acropora millepora larval metamorphosis, including cell proliferation, apoptosis, differentiation, migration, adhesion and biomineralisation, two novel coral gene expression assays were implemented. These involved the use of reverse-transcriptase quantitative PCR (RT-qPCR) and employed 47 genes of interest (GOI), selected based on putative roles in the processes of settlement and metamorphosis. Substantial differences in transcriptomic responses of GOI were detected following incubation of A. millepora larvae with a threshold concentration and 10-fold elevated concentration of TBP-containing extracts of Pseudoalteromonas sp. The notable and relatively abrupt changes of the larval body structure during metamorphosis correlated, at the molecular level, with significant differences (p<0.05) in gene expression profiles of 24 GOI, 12 hours post exposure. Fourteen of those GOI also presented differences in expression (p<0.05) following exposure to the threshold concentration of bacterial TBP-containing extract. The specificity of the bacterial TBP-containing extract to induce the metamorphic stage in A. millepora larvae without attachment, using a robust, low cost, accurate, ecologically relevant and highly reproducible RT-qPCR assay, allowed partially decoupling of the transcriptomic processes of attachment and metamorphosis. The bacterial TBP-containing extract provided a unique opportunity to monitor the regulation of genes exclusively involved in the process of metamorphosis, contrasting previous gene expression studies that utilized cues, such as crustose coralline algae, biofilms or with GLW-amide neuropeptides that stimulate the entire onset of larval metamorphosis and attachment.
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Affiliation(s)
- Nachshon Siboni
- Australian Institute of Marine Science, Townsville, Australia.
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Sasakura Y, Mita K, Ogura Y, Horie T. Ascidians as excellent chordate models for studying the development of the nervous system during embryogenesis and metamorphosis. Dev Growth Differ 2012; 54:420-37. [DOI: 10.1111/j.1440-169x.2012.01343.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Yasunori Sasakura
- Shimoda Marine Research Center; University of Tsukuba; Shimoda; Shizuoka; 415-0025; Japan
| | - Kaoru Mita
- Shimoda Marine Research Center; University of Tsukuba; Shimoda; Shizuoka; 415-0025; Japan
| | - Yosuke Ogura
- Shimoda Marine Research Center; University of Tsukuba; Shimoda; Shizuoka; 415-0025; Japan
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Stolfi A, Wagner E, Taliaferro JM, Chou S, Levine M. Neural tube patterning by Ephrin, FGF and Notch signaling relays. Development 2012; 138:5429-39. [PMID: 22110057 DOI: 10.1242/dev.072108] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The motor ganglion (MG) controls the rhythmic swimming behavior of the Ciona intestinalis tadpole. Despite its cellular simplicity (five pairs of neurons), the MG exhibits conservation of transcription factor expression with the spinal cord of vertebrates. Evidence is presented that the developing MG is patterned by sequential Ephrin/FGF/MAPK and Delta/Notch signaling events. FGF/MAPK attenuation by a localized EphrinAb signal specifies posterior neuronal subtypes, which in turn relay a Delta2/Notch signal that specifies anterior fates. This short-range relay is distinct from the patterning of the vertebrate spinal cord, which is a result of opposing BMP and Shh morphogen gradients. Nonetheless, both mechanisms lead to localized expression of related homeodomain codes for the specification of distinct neuronal subtypes. This MG regulatory network provides a foundation for elucidating the genetic and cellular basis of a model chordate central pattern generator.
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Affiliation(s)
- Alberto Stolfi
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development, Center for Integrative Genomics, University of California, Berkeley, CA 94720, USA.
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Nishitsuji K, Horie T, Ichinose A, Sasakura Y, Yasuo H, Kusakabe TG. Cell lineage and cis-regulation for a unique GABAergic/glycinergic neuron type in the larval nerve cord of the ascidian Ciona intestinalis. Dev Growth Differ 2012; 54:177-86. [DOI: 10.1111/j.1440-169x.2011.01319.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Coordinated regulation of cholinergic motor neuron traits through a conserved terminal selector gene. Nat Neurosci 2011; 15:205-14. [PMID: 22119902 PMCID: PMC3267877 DOI: 10.1038/nn.2989] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 10/28/2011] [Indexed: 11/08/2022]
Abstract
Cholinergic motor neurons are defined by the coexpression of a battery of genes encoding proteins that act sequentially to synthesize, package and degrade acetylcholine and reuptake its breakdown product, choline. How expression of these critical motor neuron identity determinants is controlled and coordinated is not understood. We show here that, in the nematode Caenorhabditis elegans, all members of the cholinergic gene battery, as well as many other markers of terminal motor neuron fate, are co-regulated by a shared cis-regulatory signature and a common trans-acting factor, the phylogenetically conserved COE (Collier, Olf, EBF)-type transcription factor UNC-3. UNC-3 initiated and maintained expression of cholinergic fate markers and was sufficient to induce cholinergic fate in other neuron types. UNC-3 furthermore operated in negative feedforward loops to induce the expression of transcription factors that repress individual UNC-3-induced terminal fate markers, resulting in diversification of motor neuron differentiation programs in specific motor neuron subtypes. A chordate ortholog of UNC-3, Ciona intestinalis COE, was also both required and sufficient for inducing a cholinergic fate. Thus, UNC-3 is a terminal selector for cholinergic motor neuron differentiation whose function is conserved across phylogeny.
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Ikuta T. Evolution of invertebrate deuterostomes and Hox/ParaHox genes. GENOMICS, PROTEOMICS & BIOINFORMATICS 2011; 9:77-96. [PMID: 21802045 PMCID: PMC5054439 DOI: 10.1016/s1672-0229(11)60011-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 03/21/2011] [Indexed: 11/10/2022]
Abstract
Transcription factors encoded by Antennapedia-class homeobox genes play crucial roles in controlling development of animals, and are often found clustered in animal genomes. The Hox and ParaHox gene clusters have been regarded as evolutionary sisters and evolved from a putative common ancestral gene complex, the ProtoHox cluster, prior to the divergence of the Cnidaria and Bilateria (bilaterally symmetrical animals). The Deuterostomia is a monophyletic group of animals that belongs to the Bilateria, and a sister group to the Protostomia. The deuterostomes include the vertebrates (to which we belong), invertebrate chordates, hemichordates, echinoderms and possibly xenoturbellids, as well as acoelomorphs. The studies of Hox and ParaHox genes provide insights into the origin and subsequent evolution of the bilaterian animals. Recently, it becomes apparent that among the Hox and ParaHox genes, there are significant variations in organization on the chromosome, expression pattern, and function. In this review, focusing on invertebrate deuterostomes, I first summarize recent findings about Hox and ParaHox genes. Next, citing unsolved issues, I try to provide clues that might allow us to reconstruct the common ancestor of deuterostomes, as well as understand the roles of Hox and ParaHox genes in the development and evolution of deuterostomes.
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Affiliation(s)
- Tetsuro Ikuta
- Marine Genomics Unit, Okinawa Institute of Science and Technology, Uruma, Japan.
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Hudson C, Ba M, Rouvière C, Yasuo H. Divergent mechanisms specify chordate motoneurons: evidence from ascidians. Development 2011; 138:1643-52. [DOI: 10.1242/dev.055426] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ascidians are members of the vertebrate sister group Urochordata. Their larvae exhibit a chordate body plan, which forms by a highly accelerated embryonic strategy involving a fixed cell lineage and small cell numbers. We report a detailed analysis of the specification of three of the five pairs of motoneurons in the ascidian Ciona intestinalis and show that despite well-conserved gene expression patterns and embryological outcomes compared with vertebrates, key signalling molecules have adopted different roles. We employed a combination of cell ablation and gene manipulation to analyse the function of two signalling molecules with key roles in vertebrate motoneuron specification that are known to be expressed equivalently in ascidians: the inducer Sonic hedgehog, produced ventrally by the notochord and floorplate; and the inhibitory BMP2/4, produced on the lateral/dorsal side of the neural plate. Our surprising conclusion is that neither BMP2/4 signalling nor the ventral cell lineages expressing hedgehog play crucial roles in motoneuron formation in Ciona. Furthermore, BMP2/4 overexpression induced ectopic motoneurons, the opposite of its vertebrate role. We suggest that the specification of motoneurons has been modified during ascidian evolution, such that BMP2/4 has adopted a redundant inductive role rather than a repressive role and Nodal, expressed upstream of BMP2/4 in the dorsal neural tube precursors, acts as a motoneuron inducer during normal development. Thus, our results uncover significant differences in the mechanisms used for motoneuron specification within chordates and also highlight the dangers of interpreting equivalent expression patterns as indicative of conserved function in evo-devo studies.
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Affiliation(s)
- Clare Hudson
- UPMC University of Paris 06, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, BP28, 06230, Villefranche-sur-mer, France
- CNRS, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, 06230, BP28, Villefranche-sur-mer, France
| | - Moly Ba
- UPMC University of Paris 06, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, BP28, 06230, Villefranche-sur-mer, France
- CNRS, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, 06230, BP28, Villefranche-sur-mer, France
| | - Christian Rouvière
- UPMC University of Paris 06, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, BP28, 06230, Villefranche-sur-mer, France
- CNRS, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, 06230, BP28, Villefranche-sur-mer, France
| | - Hitoyoshi Yasuo
- UPMC University of Paris 06, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, BP28, 06230, Villefranche-sur-mer, France
- CNRS, UMR7009, Developmental Biology Unit, Observatoire Océanologique de Villefranche-sur-mer, 06230, BP28, Villefranche-sur-mer, France
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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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Nishino A, Baba SA, Okamura Y. A mechanism for graded motor control encoded in the channel properties of the muscle ACh receptor. Proc Natl Acad Sci U S A 2011; 108:2599-604. [PMID: 21262828 PMCID: PMC3038724 DOI: 10.1073/pnas.1013547108] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The larva of the invertebrate chordate Ciona intestinalis possesses only 36 striated muscle cells and lacks body segmentation. It can swim, however, like a vertebrate tadpole, and how its simple body achieves such sophisticated motor control remains puzzling. We found that muscle contractions in Ciona larvae are variable and can be changed by sensory stimuli, so that neuromuscular transmission can convert the variable neural inputs into graded muscle activity. We characterized the molecular nature of the nicotinic acetylcholine receptor (nAChR) at neuromuscular synapses. When heterologously expressed in Xenopus oocytes, this nAChR channel exhibited two biophysical features resembling vertebrate neuronal nAChRs rather than the muscle type: inward rectification and high Ca(2+) permeability. Both of these properties were abolished by a simple mutation at the channel pore in one of the non-α subunits, called BGDE3, so as to adopt the sequence of related subunits in vertebrates, γ and ε. In vivo exchange of native BGDE3 with this mutant severely disrupted graded motor control, producing instead sporadic all-or-none-like flexions. The graded nature of excitation-contraction (E-C) coupling in this organism is based on the traits of the nAChR channel pore, which confer fine controllability on such a coarse motor architecture.
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Affiliation(s)
- Atsuo Nishino
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
- Okazaki Institute for Integrative Bioscience and
| | - Shoji A. Baba
- Department of Biological Sciences, Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo 112-8610, Japan
| | - Yasushi Okamura
- Department of Integrative Physiology, Graduate School of Medicine, Osaka University, Osaka 560-0871, Japan; and
- Okazaki Institute for Integrative Bioscience and
- National Institute for Physiological Sciences, National Institutes of Natural Sciences, Aichi 444-8787, Japan
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Ependymal cells of chordate larvae are stem-like cells that form the adult nervous system. Nature 2011; 469:525-8. [PMID: 21196932 DOI: 10.1038/nature09631] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 10/27/2010] [Indexed: 12/27/2022]
Abstract
In ascidian tunicates, the metamorphic transition from larva to adult is accompanied by dynamic changes in the body plan. For instance, the central nervous system (CNS) is subjected to extensive rearrangement because its regulating larval organs are lost and new adult organs are created. To understand how the adult CNS is reconstructed, we traced the fate of larval CNS cells during ascidian metamorphosis by using transgenic animals and imaging technologies with photoconvertible fluorescent proteins. Here we show that most parts of the ascidian larval CNS, except for the tail nerve cord, are maintained during metamorphosis and recruited to form the adult CNS. We also show that most of the larval neurons disappear and only a subset of cholinergic motor neurons and glutamatergic neurons are retained. Finally, we demonstrate that ependymal cells of the larval CNS contribute to the construction of the adult CNS and that some differentiate into neurons in the adult CNS. An unexpected role of ependymal cells highlighted by this study is that they serve as neural stem-like cells to reconstruct the adult nervous network during chordate metamorphosis. Consequently, the plasticity of non-neuronal ependymal cells and neuronal cells in chordates should be re-examined by future studies.
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