1
|
Anselmi C, Fuller GK, Stolfi A, Groves AK, Manni L. Sensory cells in tunicates: insights into mechanoreceptor evolution. Front Cell Dev Biol 2024; 12:1359207. [PMID: 38550380 PMCID: PMC10973136 DOI: 10.3389/fcell.2024.1359207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/04/2024] [Indexed: 04/04/2024] Open
Abstract
Tunicates, the sister group of vertebrates, offer a unique perspective for evolutionary developmental studies (Evo-Devo) due to their simple anatomical organization. Moreover, the separation of tunicates from vertebrates predated the vertebrate-specific genome duplications. As adults, they include both sessile and pelagic species, with very limited mobility requirements related mainly to water filtration. In sessile species, larvae exhibit simple swimming behaviors that are required for the selection of a suitable substrate on which to metamorphose. Despite their apparent simplicity, tunicates display a variety of mechanoreceptor structures involving both primary and secondary sensory cells (i.e., coronal sensory cells). This review encapsulates two decades of research on tunicate mechanoreception focusing on the coronal organ's sensory cells as prime candidates for understanding the evolution of vertebrate hair cells of the inner ear and the lateral line organ. The review spans anatomical, cellular and molecular levels emphasizing both similarity and differences between tunicate and vertebrate mechanoreception strategies. The evolutionary significance of mechanoreception is discussed within the broader context of Evo-Devo studies, shedding light on the intricate pathways that have shaped the sensory system in chordates.
Collapse
Affiliation(s)
- Chiara Anselmi
- Hopkins Marine Station, Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Pacific Grove, CA, United States
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, United States
| | - Gwynna K. Fuller
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Andrew K. Groves
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
| | - Lucia Manni
- Dipartimento di Biologia, Università degli Studi di Padova, Padova, Italy
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Pickett CJ, Gruner HN, Davidson B. Lhx3/4 initiates a cardiopharyngeal-specific transcriptional program in response to widespread FGF signaling. PLoS Biol 2024; 22:e3002169. [PMID: 38271304 PMCID: PMC10810493 DOI: 10.1371/journal.pbio.3002169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 12/21/2023] [Indexed: 01/27/2024] Open
Abstract
Individual signaling pathways, such as fibroblast growth factors (FGFs), can regulate a plethora of inductive events. According to current paradigms, signal-dependent transcription factors (TFs), such as FGF/MapK-activated Ets family factors, partner with lineage-determining factors to achieve regulatory specificity. However, many aspects of this model have not been rigorously investigated. One key question relates to whether lineage-determining factors dictate lineage-specific responses to inductive signals or facilitate these responses in collaboration with other inputs. We utilize the chordate model Ciona robusta to investigate mechanisms generating lineage-specific induction. Previous studies in C. robusta have shown that cardiopharyngeal progenitor cells are specified through the combined activity of FGF-activated Ets1/2.b and an inferred ATTA-binding transcriptional cofactor. Here, we show that the homeobox TF Lhx3/4 serves as the lineage-determining TF that dictates cardiopharyngeal-specific transcription in response to pleiotropic FGF signaling. Targeted knockdown of Lhx3/4 leads to loss of cardiopharyngeal gene expression. Strikingly, ectopic expression of Lhx3/4 in a neuroectodermal lineage subject to FGF-dependent specification leads to ectopic cardiopharyngeal gene expression in this lineage. Furthermore, ectopic Lhx3/4 expression disrupts neural plate morphogenesis, generating aberrant cell behaviors associated with execution of incompatible morphogenetic programs. Based on these findings, we propose that combinatorial regulation by signal-dependent and lineage-determinant factors represents a generalizable, previously uncategorized regulatory subcircuit we term "cofactor-dependent induction." Integration of this subcircuit into theoretical models will facilitate accurate predictions regarding the impact of gene regulatory network rewiring on evolutionary diversification and disease ontogeny.
Collapse
Affiliation(s)
- C. J. Pickett
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Hannah N. Gruner
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Bradley Davidson
- Department of Biology, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| |
Collapse
|
4
|
Matsuo K, Tamura R, Hotta K, Okada M, Takeuchi A, Wu Y, Hashimoto K, Takano H, Momose A, Nishino A. Bilaterally Asymmetric Helical Myofibrils in Ascidian Tadpole Larvae. Front Cell Dev Biol 2021; 9:800455. [PMID: 34950666 PMCID: PMC8688927 DOI: 10.3389/fcell.2021.800455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 11/18/2021] [Indexed: 11/13/2022] Open
Abstract
The locomotor system is highly bilateral at the macroscopic level. Homochirality of biological molecules is fully compatible with the bilateral body. However, whether and how single-handed cells contribute to the bilateral locomotor system is obscure. Here, exploiting the small number of cells in the swimming tadpole larva of the ascidian Ciona, we analyzed morphology of the tail at cellular and subcellular scales. Quantitative phase-contrast X-ray tomographic microscopy revealed a high-density midline structure ventral to the notochord in the tail. Muscle cell nuclei on each side of the notochord were roughly bilaterally aligned. However, fluorescence microscopy detected left-right asymmetry of myofibril inclination relative to the longitudinal axis of the tail. Zernike phase-contrast X-ray tomographic microscopy revealed the presence of left-handed helices of myofibrils in muscle cells on both sides. Therefore, the locomotor system of ascidian larvae harbors symmetry-breaking left-handed helical cells, while maintaining bilaterally symmetrical cell alignment. These results suggest that bilateral animals can override cellular homochirality to generate the bilateral locomotor systems at the supracellular scale.
Collapse
Affiliation(s)
- Koichi Matsuo
- Laboratory of Cell and Tissue Biology, Keio University School of Medicine, Tokyo, Japan
| | - Ryota Tamura
- Department of Neurosurgery, Keio University School of Medicine, Tokyo, Japan
| | - Kohji Hotta
- Department of Biosciences and Informatics, Faculty of Science and Technology, Keio University, Yokohama, Japan
| | - Mayu Okada
- Laboratory of Cell and Tissue Biology, Keio University School of Medicine, Tokyo, Japan
| | - Akihisa Takeuchi
- Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Japan
| | - Yanlin Wu
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Koh Hashimoto
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Hidekazu Takano
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Atsushi Momose
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan
| | - Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Japan
| |
Collapse
|
5
|
Jeon DJ, Paik S, Ji S, Yeo JS. Melanin-based structural coloration of birds and its biomimetic applications. Appl Microsc 2021; 51:14. [PMID: 34633588 PMCID: PMC8505553 DOI: 10.1186/s42649-021-00063-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/24/2021] [Indexed: 11/29/2022] Open
Abstract
Melanin has been a widely researched pigment by scientists for decades as it is undoubtedly the most ubiquitous and ancient pigment found in nature. Melanin plays very significant roles in structural plumage colors in birds: it has visible light-absorbing capabilities, and nanoscale structures can be formed by self-assembling melanin granules. Herein, we review recent progress on melanin-based structural coloration research. We hope that this review will provide current understanding of melanin's structural and optical properties, natural coloration mechanisms, and biomimetic methods to implement artificial melanin-based structural colors.
Collapse
Affiliation(s)
- Deok-Jin Jeon
- School of Integrated Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea
- Yonsei Institute of Convergence Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea
| | - Suejeong Paik
- 39 Yeonhui-ro 22-gil, Seodaemun-gu, Seoul, 03723, Republic of Korea
| | - Seungmuk Ji
- School of Integrated Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea
- Yonsei Institute of Convergence Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea
| | - Jong-Souk Yeo
- School of Integrated Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
- Yonsei Institute of Convergence Technology, Yonsei University, 85 Songdogwahak-ro, Yeonsu-gu, Incheon, 21983, Republic of Korea.
| |
Collapse
|
6
|
Olivo P, Palladino A, Ristoratore F, Spagnuolo A. Brain Sensory Organs of the Ascidian Ciona robusta: Structure, Function and Developmental Mechanisms. Front Cell Dev Biol 2021; 9:701779. [PMID: 34552923 PMCID: PMC8450388 DOI: 10.3389/fcell.2021.701779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022] Open
Abstract
During evolution, new characters are designed by modifying pre-existing structures already present in ancient organisms. In this perspective, the Central Nervous System (CNS) of ascidian larva offers a good opportunity to analyze a complex phenomenon with a simplified approach. As sister group of vertebrates, ascidian tadpole larva exhibits a dorsal CNS, made up of only about 330 cells distributed into the anterior sensory brain vesicle (BV), connected to the motor ganglion (MG) and a caudal nerve cord (CNC) in the tail. Low number of cells does not mean, however, low complexity. The larval brain contains 177 neurons, for which a documented synaptic connectome is now available, and two pigmented organs, the otolith and the ocellus, controlling larval swimming behavior. The otolith is involved in gravity perception and the ocellus in light perception. Here, we specifically review the studies focused on the development of the building blocks of ascidians pigmented sensory organs, namely pigment cells and photoreceptor cells. We focus on what it is known, up to now, on the molecular bases of specification and differentiation of both lineages, on the function of these organs after larval hatching during pre-settlement period, and on the most cutting-edge technologies, like single cell RNAseq and genome editing CRISPR/CAS9, that, adapted and applied to Ciona embryos, are increasingly enhancing the tractability of Ciona for developmental studies, including pigmented organs formation.
Collapse
Affiliation(s)
- Paola Olivo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonio Palladino
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Filomena Ristoratore
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonietta Spagnuolo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| |
Collapse
|
7
|
Kourakis MJ, Bostwick M, Zabriskie A, Smith WC. Disruption of left-right axis specification in Ciona induces molecular, cellular, and functional defects in asymmetric brain structures. BMC Biol 2021; 19:141. [PMID: 34256748 PMCID: PMC8276506 DOI: 10.1186/s12915-021-01075-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/17/2021] [Indexed: 11/28/2022] Open
Abstract
Background Left-right asymmetries are a common feature of metazoans and can be found in a number of organs including the nervous system. These asymmetries are particularly pronounced in the simple central nervous system (CNS) of the swimming tadpole larva of the tunicate Ciona, which displays a chordate ground plan. While common pathway elements for specifying the left/right axis are found among chordates, particularly a requirement for Nodal signaling, Ciona differs temporally from its vertebrate cousins by specifying its axis at the neurula stage, rather than at gastrula. Additionally, Ciona and other ascidians require an intact chorionic membrane for proper left-right specification. Whether such differences underlie distinct specification mechanisms between tunicates and vertebrates will require broad understanding of their influence on CNS formation. Here, we explore the consequences of disrupting left-right axis specification on Ciona larval CNS cellular anatomy, gene expression, synaptic connectivity, and behavior. Results We show that left-right asymmetry disruptions caused by removal of the chorion (dechorionation) are highly variable and present throughout the Ciona larval nervous system. While previous studies have documented disruptions to the conspicuously asymmetric sensory systems in the anterior brain vesicle, we document asymmetries in seemingly symmetric structures such as the posterior brain vesicle and motor ganglion. Moreover, defects caused by dechorionation include misplaced or absent neuron classes, loss of asymmetric gene expression, aberrant synaptic projections, and abnormal behaviors. In the motor ganglion, a brain structure that has been equated with the vertebrate hindbrain, we find that despite the apparent left-right symmetric distribution of interneurons and motor neurons, AMPA receptors are expressed exclusively on the left side, which equates with asymmetric swimming behaviors. We also find that within a population of dechorionated larvae, there is a small percentage with apparently normal left-right specification and approximately equal population with inverted (mirror-image) asymmetry. We present a method based on a behavioral assay for isolating these larvae. When these two classes of larvae (normal and inverted) are assessed in a light dimming assay, they display mirror-image behaviors, with normal larvae responding with counterclockwise swims, while inverted larvae respond with clockwise swims. Conclusions Our findings highlight the importance of left-right specification pathways not only for proper CNS anatomy, but also for correct synaptic connectivity and behavior. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01075-4.
Collapse
Affiliation(s)
- Matthew J Kourakis
- Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Michaela Bostwick
- College of Creative Studies, University of California, Santa Barbara, CA, 93106, USA
| | - Amanda Zabriskie
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA
| | - William C Smith
- Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA. .,Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, CA, 93106, USA.
| |
Collapse
|
8
|
Coppola U, Kamal AK, Stolfi A, Ristoratore F. The Cis-Regulatory Code for Kelch-like 21/30 Specific Expression in Ciona robusta Sensory Organs. Front Cell Dev Biol 2020; 8:569601. [PMID: 33043001 PMCID: PMC7517041 DOI: 10.3389/fcell.2020.569601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 08/17/2020] [Indexed: 12/18/2022] Open
Abstract
The tunicate Ciona robusta is an emerging model system to study the evolution of the nervous system. Due to their small embryos and compact genomes, tunicates, like Ciona robusta, have great potential to comprehend genetic circuitry underlying cell specific gene repertoire, among different neuronal cells. Their simple larvae possess a sensory vesicle comprising two pigmented sensory organs, the ocellus and the otolith. We focused here on Klhl21/30, a gene belonging to Kelch family, that, in Ciona robusta, starts to be expressed in pigmented cell precursors, becoming specifically maintained in the otolith precursor during embryogenesis. Evolutionary analyses demonstrated the conservation of Klhl21/30 in all the chordates. Cis-regulatory analyses and CRISPR/Cas9 mutagenesis of potential upstream factors, revealed that Klhl21/30 expression is controlled by the combined action of three transcription factors, Mitf, Dmrt, and Msx, which are downstream of FGF signaling. The central role of Mitf is consistent with its function as a fundamental regulator of vertebrate pigment cell development. Moreover, our results unraveled a new function for Dmrt and Msx as transcriptional co-activators in the context of the Ciona otolith.
Collapse
Affiliation(s)
- Ugo Coppola
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Naples, Italy.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Ashwani Kumar Kamal
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Naples, Italy
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Filomena Ristoratore
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn Napoli, Naples, Italy
| |
Collapse
|
9
|
Bostwick M, Smith EL, Borba C, Newman-Smith E, Guleria I, Kourakis MJ, Smith WC. Antagonistic Inhibitory Circuits Integrate Visual and Gravitactic Behaviors. Curr Biol 2020; 30:600-609.e2. [PMID: 32008899 PMCID: PMC7066595 DOI: 10.1016/j.cub.2019.12.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/03/2019] [Accepted: 12/05/2019] [Indexed: 01/01/2023]
Abstract
Larvae of the tunicate Ciona intestinalis possess a central nervous system of 177 neurons. This simplicity has facilitated the generation of a complete synaptic connectome. As chordates and the closest relatives of vertebrates, tunicates promise insight into the organization and evolution of vertebrate nervous systems. Ciona larvae have several sensory systems, including the ocellus and otolith, which are sensitive to light and gravity, respectively. Here, we describe circuitry by which these two are integrated into a complex behavior: the rapid reorientation of the body followed by upward swimming in response to dimming. Significantly, the gravity response causes an orienting behavior consisting of curved swims in downward-facing larvae but only when triggered by dimming. In contrast, the majority of larvae facing upward do not respond to dimming with orientation swims-but instead swim directly upward. Under constant light conditions, the gravity circuit appears to be inoperable, and both upward and downward swims were observed. Using connectomic and neurotransmitter data, we propose a circuit model that can account for these behaviors. The otolith consists of a statocyst cell and projecting excitatory sensory neurons (antenna cells). Postsynaptic to the antenna cells are a group of inhibitory primary interneurons, the antenna relay neurons (antRNs), which then project asymmetrically to the right and left motor units, thereby mediating curved orientation swims. Also projecting to the antRNs are inhibitory photoreceptor relay interneurons. These interneurons appear to antagonize the otolith circuit until they themselves are inhibited by photoreceptors in response to dimming, thus providing a triggering circuit.
Collapse
Affiliation(s)
- Michaela Bostwick
- Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Eleanor L Smith
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616, USA
| | - Cezar Borba
- 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; Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Iraa Guleria
- 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.
| |
Collapse
|
10
|
Bezares-Calderón LA, Berger J, Jékely G. Diversity of cilia-based mechanosensory systems and their functions in marine animal behaviour. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190376. [PMID: 31884914 PMCID: PMC7017336 DOI: 10.1098/rstb.2019.0376] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/03/2019] [Indexed: 12/12/2022] Open
Abstract
Sensory cells that detect mechanical forces usually have one or more specialized cilia. These mechanosensory cells underlie hearing, proprioception or gravity sensation. To date, it is unclear how cilia contribute to detecting mechanical forces and what is the relationship between mechanosensory ciliated cells in different animal groups and sensory systems. Here, we review examples of ciliated sensory cells with a focus on marine invertebrate animals. We discuss how various ciliated cells mediate mechanosensory responses during feeding, tactic responses or predator-prey interactions. We also highlight some of these systems as interesting and accessible models for future in-depth behavioural, functional and molecular studies. We envisage that embracing a broader diversity of organisms could lead to a more complete view of cilia-based mechanosensation. This article is part of the Theo Murphy meeting issue 'Unity and diversity of cilia in locomotion and transport'.
Collapse
Affiliation(s)
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| |
Collapse
|
11
|
Gomes IDL, Gazo I, Nabi D, Besnardeau L, Hebras C, McDougall A, Dumollard R. Bisphenols disrupt differentiation of the pigmented cells during larval brain formation in the ascidian. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 216:105314. [PMID: 31561137 DOI: 10.1016/j.aquatox.2019.105314] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 09/12/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
The endocrine disruptor Bisphenol A (BPA), a widely employed molecule in plastics, has been shown to affect several biological processes in vertebrates, mostly via binding to nuclear receptors. Neurodevelopmental effects of BPA have been documented in vertebrates and linked to neurodevelopmental disorders, probably because some nuclear receptors are present in the vertebrate brain. Similarly, endocrine disruptors have been shown to affect neurodevelopment in marine invertebrates such as ascidians, mollusks or echinoderms, but whether invertebrate nuclear receptors are involved in the mode-of-action is largely unknown. In this study, we assessed the effect of BPA on larval brain development of the ascidian Phallusia mammillata. We found that BPA is toxic to P. mammillata embryos in a dose-dependent manner (EC50: 11.8μM; LC50: 21μM). Furthermore, micromolar doses of BPA impaired differentiation of the ascidian pigmented cells, by inhibiting otolith movement within the sensory vesicle. We further show that this phenotype is specific to other two bisphenols (BPE and BPF) over a bisphenyl (2,2 DPP). Because in vertebrates the estrogen-related receptor gamma (ERRγ) can bind bisphenols with high affinity but not bisphenyls, we tested whether the ascidian ERR participates in the neurodevelopmental phenotype induced by BPA. Interestingly, P. mammillata ERR is expressed in the larval brain, adjacent to the differentiating otolith. Furthermore, antagonists of vertebrate ERRs also inhibited the otolith movement but not pigmentation. Together our observations suggest that BPA may affect ascidian otolith differentiation by altering Pm-ERR activity whereas otolith pigmentation defects might be due to the known inhibitory effect of bisphenols on tyrosinase enzymatic activity.
Collapse
Affiliation(s)
- Isa D L Gomes
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France.
| | - Ievgeniia Gazo
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France; University of South Bohemia in Ceske Budejovice, Faculty of Fisheries and Protection of Waters, Research Institute of Fish Culture and Hydrobiology, Laboratory of Molecular, Cellular and Quantitative Genetics, Zátiší 728/II, 389 25, Vodňany, Czech Republic
| | - Dalileh Nabi
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France
| | - Lydia Besnardeau
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France
| | - Céline Hebras
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France
| | - Alex McDougall
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France
| | - Rémi Dumollard
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV) UMR7009, Sorbonne Universités, Université Pierre-et-Marie-Curie, CNRS, Institut de la Mer de Villefranche (IMEV), Villefranche-sur-mer, France.
| |
Collapse
|
12
|
Roskamp KW, Kozlyuk N, Sengupta S, Bierma JC, Martin RW. Divalent Cations and the Divergence of βγ-Crystallin Function. Biochemistry 2019; 58:4505-4518. [PMID: 31647219 DOI: 10.1021/acs.biochem.9b00507] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The βγ-crystallin superfamily contains both β- and γ-crystallins of the vertebrate eye lens and the microbial calcium-binding proteins, all of which are characterized by a common double-Greek key domain structure. The vertebrate βγ-crystallins are long-lived structural proteins that refract light onto the retina. In contrast, the microbial βγ-crystallins bind calcium ions. The βγ-crystallin from the tunicate Ciona intestinalis (Ci-βγ) provides a potential link between these two functions. It binds calcium with high affinity and is found in a light-sensitive sensory organ that is highly enriched in metal ions. Thus, Ci-βγ is valuable for investigating the evolution of the βγ-crystallin fold away from calcium binding and toward stability in the apo form as part of the vertebrate lens. Here, we investigate the effect of Ca2+ and other divalent cations on the stability and aggregation propensity of Ci-βγ and human γS-crystallin (HγS). Beyond Ca2+, Ci-βγ is capable of coordinating Mg2+, Sr2+, Co2+, Mn2+, Ni2+, and Zn2+, although only Sr2+ is bound with comparable affinity to its preferred metal ion. The extent to which the tested divalent cations stabilize Ci-βγ structure correlates strongly with ionic radius. In contrast, none of the tested divalent cations improved the stability of HγS, and some of them induced aggregation. Zn2+, Ni2+, and Co2+ induce aggregation by interacting with cysteine residues, whereas Cu2+-mediated aggregation proceeds via a different binding site.
Collapse
Affiliation(s)
- Kyle W Roskamp
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Natalia Kozlyuk
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Suvrajit Sengupta
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States
| | - Jan C Bierma
- Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
| | - Rachel W Martin
- Department of Chemistry , University of California , Irvine , California 92697-2025 , United States.,Department of Molecular Biology and Biochemistry , University of California , Irvine , California 92697-3900 , United States
| |
Collapse
|
13
|
Zeng F, Wunderer J, Salvenmoser W, Hess MW, Ladurner P, Rothbächer U. Papillae revisited and the nature of the adhesive secreting collocytes. Dev Biol 2019; 448:183-198. [DOI: 10.1016/j.ydbio.2018.11.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 11/17/2018] [Accepted: 11/20/2018] [Indexed: 11/26/2022]
|
14
|
D'Alba L, Shawkey MD. Melanosomes: Biogenesis, Properties, and Evolution of an Ancient Organelle. Physiol Rev 2019; 99:1-19. [PMID: 30255724 DOI: 10.1152/physrev.00059.2017] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Melanosomes are organelles that produce and store melanin, a widespread biological pigment with a unique suite of properties including high refractive index, semiconducting capabilities, material stiffness, and high fossilization potential. They are involved in numerous critical biological functions in organisms across the tree of life. Individual components such as melanin chemistry and melanosome development have recently been addressed, but a broad synthesis is needed. Here, we review the hierarchical structure, development, functions, and evolution of melanosomes. We highlight variation in melanin chemistry and melanosome morphology and how these may relate to function. For example, we review what is known of the chemical differences between different melanin types (eumelanin, pheomelanin, allomelanin) and whether/how melanosome morphology relates to chemistry and color. We integrate the distribution of melanin across living organisms with what is known from the fossil record and produce hypotheses on its evolution. We suggest that melanin was present in life forms early in evolutionary history and that melanosomes evolved at the origin of organelles. Throughout, we discuss the (sometimes gaping) holes in our knowledge and suggest areas that need particular attention as we move forward in our understanding of these still-mysterious organelles and the materials that they contain.
Collapse
Affiliation(s)
- Liliana D'Alba
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent , Ghent , Belgium
| | - Matthew D Shawkey
- Evolution and Optics of Nanostructures Group, Department of Biology, University of Ghent , Ghent , Belgium
| |
Collapse
|
15
|
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.
Collapse
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
| |
Collapse
|
16
|
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.
Collapse
Affiliation(s)
- Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
| |
Collapse
|
17
|
Letelier J, Bovolenta P, Martínez-Morales JR. The pigmented epithelium, a bright partner against photoreceptor degeneration. J Neurogenet 2017; 31:203-215. [PMID: 29113536 DOI: 10.1080/01677063.2017.1395876] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Sight depends on the intimate association between photoreceptors and pigment epithelial cells. The evolutionary origin of this cellular tandem can be traced back to the emergence of bilateral animals, at least 450 million years ago, as they define the minimal unit of the ancestral prototypic eye. Phototransduction is a demanding process from the energetic and homeostatic points of view, and not surprisingly photoreceptive cells are particularly susceptible to damage and degeneration. Here, we will examine the different ancillary roles that the pigmented cells play in the physiology and homeostasis of photoreceptors, linking each one of these processes to the most common hereditary retinal diseases. We will discuss the challenges and opportunities of recent therapeutic advances based on cell and gene replacement. The transition from animal models to clinical trials will be addressed for each one of the different therapeutic strategies with a special focus on those depending on retinal-pigmented epithelial cells. Finally, we will discuss the potential impact of combining CRISPR technologies with gene and cell therapy approaches, which - in the frame of the personalized medicine revolution - may constitute a leap forward in the treatment of retinal dystrophies.
Collapse
Affiliation(s)
- Joaquín Letelier
- a Centro Andaluz de Biología del Desarrollo (CSIC/UPO/JA) , Seville , Spain
| | - Paola Bovolenta
- b Centro de Biología Molecular "Severo Ochoa," (CSIC/UAM) and CIBERER, ISCIII , Madrid , Spain
| | | |
Collapse
|
18
|
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]
|
19
|
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]
|
20
|
Esposito R, Racioppi C, Pezzotti MR, Branno M, Locascio A, Ristoratore F, Spagnuolo A. The ascidian pigmented sensory organs: structures and developmental programs. Genesis 2014; 53:15-33. [PMID: 25382437 DOI: 10.1002/dvg.22836] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 01/25/2023]
Abstract
The recent advances on ascidian pigment sensory organ development and function represent a fascinating platform to get insight on the basic programs of chordate eye formation. This review aims to summarize current knowledge, at the structural and molecular levels, on the two main building blocks of ascidian light sensory organ, i.e. pigment cells and photoreceptor cells. The unique features of these structures (e.g., simplicity and well characterized cell lineage) are indeed making it possible to dissect the developmental programs at single cell resolution and will soon provide a panel of molecular tools to be exploited for a deep developmental and comparative-evolutionary analysis.
Collapse
Affiliation(s)
- R Esposito
- Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, NAPOLI, Italy
| | | | | | | | | | | | | |
Collapse
|
21
|
Wagner E, Stolfi A, Gi Choi Y, Levine M. Islet is a key determinant of ascidian palp morphogenesis. Development 2014; 141:3084-92. [PMID: 24993943 DOI: 10.1242/dev.110684] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The anterior-most ectoderm of ascidian larvae contains the adhesive papillae, or palps, which play an important role in triggering the metamorphosis of swimming tadpoles. In Ciona intestinalis, the palps consist of three conical protrusions within a field of thickened epithelium that form late in embryogenesis, as tailbuds mature into larvae. The palp protrusions express the LIM-homeodomain transcription factor Islet. Protrusion occurs through differential cell elongation, probably mediated by Islet, as we find that ectopic expression of Islet is sufficient to promote cell lengthening. FGF signaling is required for both Islet expression and palp morphogenesis. Importantly, we show that Islet expression can rescue the palp-deficient phenotype that results from inhibition of FGF signaling. We conclude that Islet is a key regulatory factor governing morphogenesis of the palps. It is conceivable that Islet is also essential for the cellular morphogenesis of placode-derived sensory neurons in vertebrates.
Collapse
Affiliation(s)
- Eileen Wagner
- Center for Integrative Genomics, Division of Genetics, Genomics, and Development, Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Alberto Stolfi
- New York University, Center for Developmental Genetics, Department of Biology, 1009 Silver Center, 100 Washington Square East, New York, NY 10003-6688, USA
| | - Yoon Gi Choi
- Functional Genomics Laboratory, Department of Molecular and Cell Biology, University of California-Berkeley, 255 Life Sciences Addition #3200, Berkeley, CA 94720-3200, USA
| | - Mike Levine
- Center for Integrative Genomics, Division of Genetics, Genomics, and Development, Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| |
Collapse
|
22
|
Ivashkin E, Adameyko I. Progenitors of the protochordate ocellus as an evolutionary origin of the neural crest. EvoDevo 2013; 4:12. [PMID: 23575111 PMCID: PMC3626940 DOI: 10.1186/2041-9139-4-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 12/28/2012] [Indexed: 01/01/2023] Open
Abstract
The neural crest represents a highly multipotent population of embryonic stem cells found only in vertebrate embryos. Acquisition of the neural crest during the evolution of vertebrates was a great advantage, providing Chordata animals with the first cellular cartilage, bone, dentition, advanced nervous system and other innovations. Today not much is known about the evolutionary origin of neural crest cells. Here we propose a novel scenario in which the neural crest originates from neuroectodermal progenitors of the pigmented ocelli in Amphioxus-like animals. We suggest that because of changes in photoreception needs, these multipotent progenitors of photoreceptors gained the ability to migrate outside of the central nervous system and subsequently started to give rise to neural, glial and pigmented progeny at the periphery.
Collapse
Affiliation(s)
- Evgeniy Ivashkin
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheeles vag 1 A1, Stockholm 17177, Sweden.
| | | |
Collapse
|
23
|
Slingsby C, Wistow GJ, Clark AR. Evolution of crystallins for a role in the vertebrate eye lens. Protein Sci 2013; 22:367-80. [PMID: 23389822 PMCID: PMC3610043 DOI: 10.1002/pro.2229] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 01/16/2013] [Accepted: 01/17/2013] [Indexed: 12/18/2022]
Abstract
The camera eye lens of vertebrates is a classic example of the re-engineering of existing protein components to fashion a new device. The bulk of the lens is formed from proteins belonging to two superfamilies, the α-crystallins and the βγ-crystallins. Tracing their ancestry may throw light on the origin of the optics of the lens. The α-crystallins belong to the ubiquitous small heat shock proteins family that plays a protective role in cellular homeostasis. They form enormous polydisperse oligomers that challenge modern biophysical methods to uncover the molecular basis of their assembly structure and chaperone-like protein binding function. It is argued that a molecular phenotype of a dynamic assembly suits a chaperone function as well as a structural role in the eye lens where the constraint of preventing protein condensation is paramount. The main cellular partners of α-crystallins, the β- and γ-crystallins, have largely been lost from the animal kingdom but the superfamily is hugely expanded in the vertebrate eye lens. Their structures show how a simple Greek key motif can evolve rapidly to form a complex array of monomers and oligomers. Apart from remaining transparent, a major role of the partnership of α-crystallins with β- and γ-crystallins in the lens is to form a refractive index gradient. Here, we show some of the structural and genetic features of these two protein superfamilies that enable the rapid creation of different assembly states, to match the rapidly changing optical needs among the various vertebrates.
Collapse
Affiliation(s)
- Christine Slingsby
- Department of Biological Sciences, Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom.
| | | | | |
Collapse
|
24
|
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
| | | |
Collapse
|
25
|
D'Aniello E, Pezzotti MR, Locascio A, Branno M. Onecut is a direct neural-specific transcriptional activator of Rx in Ciona intestinalis. Dev Biol 2011; 355:358-71. [PMID: 21600895 DOI: 10.1016/j.ydbio.2011.05.584] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 04/21/2011] [Accepted: 05/04/2011] [Indexed: 11/28/2022]
Abstract
Retinal homeobox (Rx) genes play a crucial and conserved role in the development of the anterior neural plate of metazoans. During chordate evolution, they have also acquired a novel function in the control of eye formation and neurogenesis. To characterize the Rx genetic cascade and shed light on the mechanisms that led to the acquisition of this new role in eye development, we studied Rx transcriptional regulation using the ascidian, Ciona intestinalis. Through deletion analysis of the Ci-Rx promoter, we have identified two distinct enhancer elements able to induce Ci-Rx specific expression in the anterior part of the CNS and in the photosensory organ at tailbud and larva stages. Bioinformatic analysis highlighted the presence of two Onecut binding sites contained in these enhancers, so we explored the role of this transcription factor in the regulation of Ci-Rx. By in situ hybridization, we first confirmed that these genes are co-expressed in the same cells. Through a series of in vivo and in vitro experiments, we then demonstrated that the two Onecut sites are responsible for enhancer activation in Ci-Rx endogenous territories. We also demonstrated in vivo that Onecut misexpression is able to induce ectopic activation of the Rx promoter. Finally, we demonstrated that Ci-Onecut is able to promote Ci-Rx expression in the sensory vesicle. Together, these results support the conclusion that in Ciona embryogenesis, Ci-Rx expression is under the control of the Onecut transcription factor and that this factor is necessary and sufficient to specifically activate Ci-Rx through two enhancer elements.
Collapse
Affiliation(s)
- Enrico D'Aniello
- Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
| | | | | | | |
Collapse
|
26
|
Tresser J, Chiba S, Veeman M, El-Nachef D, Newman-Smith E, Horie T, Tsuda M, Smith WC. doublesex/mab3 related-1 (dmrt1) is essential for development of anterior neural plate derivatives in Ciona. Development 2010; 137:2197-203. [PMID: 20530547 PMCID: PMC2882137 DOI: 10.1242/dev.045302] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/21/2010] [Indexed: 12/17/2022]
Abstract
Ascidian larvae have a hollow, dorsal central nervous system that shares many morphological features with vertebrate nervous systems yet is composed of very few cells. We show here that a null mutation in the gene dmrt1 in the ascidian Ciona savignyi results in profound abnormalities in the development of the sensory vesicle (brain), as well as other anterior ectodermal derivatives, including the palps and oral siphon primordium (OSP). Although the phenotype of the mutant embryos is variable, the majority have a complete loss of the most anterior structures (palps and OSP) and extensive disruption of sensory structures, such as the light-sensitive ocellus, in the sensory vesicle. dmrt1 is expressed early in the blastula embryo in a small group of presumptive ectodermal cells as they become restricted to anterior neural, OSP and palp fates. Despite the early and restricted expression of dmrt1, we were unable, using several independent criteria, to observe a defect in the mutant embryos until the early tailbud stage. We speculate that the variability and late onset in the phenotype may be due to partially overlapping activities of other gene products.
Collapse
Affiliation(s)
- Jason Tresser
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Shota Chiba
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Michael Veeman
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Danny El-Nachef
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Erin Newman-Smith
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Takeo Horie
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Motoyuki Tsuda
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - William C. Smith
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| |
Collapse
|
27
|
Horie T, Nakagawa M, Sasakura Y, Kusakabe TG, Tsuda M. Simple motor system of the ascidian larva: neuronal complex comprising putative cholinergic and GABAergic/glycinergic neurons. Zoolog Sci 2010; 27:181-90. [PMID: 20141423 DOI: 10.2108/zsj.27.181] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ascidian larva is an excellent model for studies of the functional organization and neuronal circuits of chordates due to its remarkably simple central nervous system (CNS), comprised of about 100 neurons. To date, however, the identities of the various neurons in the ascidian larva, particularly their neurotransmitter phenotypes, are not well established. Acetylcholine, GABA, and glycine are critical neurotransmitters for locomotion in many animals. We visualized putative cholinergic neurons and GABAergic/glycinergic neurons in the ascidian larva by immunofluorescent staining using antibodies against vesicular acetylcholine transporter (VACHT) and vesicular GABA/glycine transporter (VGAT), respectively. Neurons expressing a cholinergic phenotype were found in the brain vesicle and the visceral ganglion. Five pairs of VACHT-positive neurons were located in the visceral ganglion. These putative cholinergic neurons extended their axons posteriorly and formed nerve terminals proximal to the most anterior muscle cells in the tail. VGAT-positive neurons were located in the brain vesicle, the visceral ganglion, and the anterior nerve cord. Two distinct pairs of VGAT-positive neurons, bilaterally aligned along the anterior nerve cord, extended axons anteriorly, near to the axons of the contralateral VACHT-positive neurons. Cell bodies of the VGAT-positive neurons lay on these nerve tracts. The neuronal complex, comprising motor neurons with a cholinergic phenotype and some of the GABA/glycinergic interneurons, has structural features that are compatible with a central pattern generator (CPG) producing a rhythmic movement of the tail. The simple CPG of the ascidian larva may represent the ancestral state of the vertebrate motor system.
Collapse
Affiliation(s)
- Takeo Horie
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan.
| | | | | | | | | |
Collapse
|
28
|
Takamura K, Minamida N, Okabe S. Neural Map of the Larval Central Nervous System in the AscidianCiona intestinalis. Zoolog Sci 2010; 27:191-203. [DOI: 10.2108/zsj.27.191] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
29
|
Horie T, Nakagawa M, Sasakura Y, Kusakabe TG. Cell type and function of neurons in the ascidian nervous system. Dev Growth Differ 2009; 51:207-20. [PMID: 19379276 DOI: 10.1111/j.1440-169x.2009.01105.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ascidians, or sea squirts, are primitive chordates, and their tadpole larvae share a basic body plan with vertebrates, including a notochord and a dorsal tubular central nervous system (CNS). The CNS of the ascidian larva is formed through a process similar to vertebrate neurulation, while the ascidian CNS is remarkably simple, consisting of about 100 neurons. Recent identification of genes that are specifically expressed in a particular subtype of neurons has enabled us to reveal neuronal networks at single-cell resolution. Based on the information on neuron subtype-specific genes, different populations of neurons have been visualized by whole-mount in situ hybridization, immunohistochemical staining using specific antibodies, and fluorescence labeling of cell bodies and neurites by a fluorescence protein reporter driven by neuron-specific promoters. Neuronal populations that have been successfully visualized include glutamatergic, cholinergic, gamma-aminobutyric acid/glycinergic, and dopaminergic neurons, which have allowed us to propose functional regionalization of the CNS and a neural circuit for locomotion. Thus, the simple nervous system of the ascidian larva can serve as an attractive model system for studying the development, function, and evolution of the chordate nervous system.
Collapse
Affiliation(s)
- Takeo Horie
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka, 415-0025, Japan.
| | | | | | | |
Collapse
|
30
|
The evolution and elaboration of vertebrate neural crest cells. Curr Opin Genet Dev 2008; 18:536-43. [DOI: 10.1016/j.gde.2008.11.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 11/13/2008] [Accepted: 11/18/2008] [Indexed: 11/19/2022]
|
31
|
Nishiyama A, Fujiwara S. RNA interference by expressing short hairpin RNA in the Ciona intestinalis embryo. Dev Growth Differ 2008; 50:521-9. [PMID: 18510713 DOI: 10.1111/j.1440-169x.2008.01039.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We carried out RNA interference by expressing short hairpin RNA (shRNA) in the Ciona intestinalis embryo. For this purpose, we identified a gene encoding U6 small nuclear RNA (snRNA) in the C. intestinalis genome. The 1-kb sequence upstream of the U6 snRNA gene was sufficient for directing transcription of short RNA as revealed by Northern blot hybridization. An shRNA-expressing plasmid vector was constructed, in which shRNA-encoding oligonucleotides are inserted downstream of the U6 promoter. An shRNA that contained a sequence homologous to the C. intestinalis tyrosinase gene (Ci-tyrosinase) suppressed melanization of pigment cells in the brain of morphologically normal tailbud embryos. An shRNA that perfectly matched the translated sequence of enhanced green fluorescent protein (EGFP) (a mutant type of Aequorea victoria green fluorescent protein) suppressed the expression of the coelectroporated EGFP transgene. These results suggest that the expression of shRNA interferes with functions of both endogenous and exogenous genes. The shRNA-expressing plasmid constructed in the present study provides an easy and inexpensive alternative for the functional analysis of genes in ascidian embryos.
Collapse
Affiliation(s)
- Aya Nishiyama
- Department of Materials Science, Kochi University, Kochi-shi, Kochi, Japan
| | | |
Collapse
|
32
|
Horie T, Kusakabe T, Tsuda M. Glutamatergic networks in the Ciona intestinalis larva. J Comp Neurol 2008; 508:249-63. [PMID: 18314906 DOI: 10.1002/cne.21678] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Glutamate is a major neurotransmitter in the excitatory synapses of both vertebrate and invertebrate nervous systems and is involved in many neural processes including photo-, mechano-, and chemosensations, neural development, motor control, learning, and memory. We identified and characterized the gene (Ci-VGLUT) encoding a member of the vesicular glutamate transporter subfamily, a specific marker of glutamatergic neurons, in the ascidian Ciona intestinalis. The Ci-VGLUT gene is expressed in the adhesive organ, the epidermal neurons, and the brain vesicle, but not in the visceral ganglion. The Ci-VGLUT promoter and an anti-Ci-VGLUT antibody were used to analyze the distribution and axonal connections of prospective glutamatergic neurons in the C. intestinalis larva. The green fluorescent protein (GFP) reporter driven by the 4.6-kb upstream region of Ci-VGLUT recapitulated the endogenous gene expression patterns and visualized both the cell bodies and neurites of glutamatergic neurons. Papillar neurons of the adhesive organs, almost all epidermal neurons, the otolith cell, and ocellus photoreceptor cells were shown to be glutamatergic. Each papillar neuron connects with a rostral epidermal neuron. Axons from rostral epidermal neurons, ocellus photoreceptor cells, and neurons underlying the otolith terminate in the posterior brain vesicle. Some caudal epidermal neurons also send long axons toward the brain vesicle. The posterior brain vesicle contains a group of Ci-VGLUT-positive neurons that send axons posteriorly to the visceral ganglion. Our results suggest that glutamatergic neurotransmission plays a major role in sensory systems and in the integration of the sensory inputs of the ascidian larva.
Collapse
Affiliation(s)
- Takeo Horie
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | | | | |
Collapse
|
33
|
Horie T, Sakurai D, Ohtsuki H, Terakita A, Shichida Y, Usukura J, Kusakabe T, Tsuda M. Pigmented and nonpigmented ocelli in the brain vesicle of the ascidian larva. J Comp Neurol 2008; 509:88-102. [DOI: 10.1002/cne.21733] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
34
|
Abstract
The brain vesicle of the tadpole larva of ascidians, simple basal chordates, contains an eye-spot (ocellus), which is responsible for the photic swimming behavior. Ascidian adults also exhibit several types of light-responsive behaviors. Molecular phylogenetic studies have suggested that ascidians are the closest living relatives of vertebrates, and therefore, understanding the photoreceptive systems in ascidians is a key to uncover the origin and evolution of the vertebrate eyes. The ocellus of the ascidian larva has ciliary photoreceptors resembling those of the retina and pineal eye of vertebrates. Recent studies have indicated that the ascidian larva has phototransduction and visual cycle systems similar to those of vertebrate eyes. Comparative studies on photoreceptor systems between ascidians and vertebrates provide us clues to reconstructing the evolutionary pathway leading to the lateral and median eyes of vertebrates.
Collapse
Affiliation(s)
- Takehiro Kusakabe
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Kouto, Kamigori, Ako-gun, Hyogo, Japan.
| | | |
Collapse
|
35
|
Yoshida R, Horie T, Tsuda M, Kusakabe TG. Comparative genomics identifies a cis-regulatory module that activates transcription in specific subsets of neurons in Ciona intestinalis larvae. Dev Growth Differ 2007; 49:657-67. [PMID: 17711474 DOI: 10.1111/j.1440-169x.2007.00960.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The larval nervous system of the ascidian Ciona intestinalis exhibits an abstract form of the vertebrate nervous system. The Ci-Galphai1 gene, which encodes a G-protein alpha subunit, is specifically expressed in distinct sets of neurons in C. intestinalis larvae, including papillar neurons of the adhesive organ, ocellus photoreceptor cells, and cholinergic and GABAergic neurons in the central nervous system (CNS). A GFP reporter gene driven by the 4.2-kb 5' flanking region of Ci-Galphai1 recapitulated the endogenous gene expression patterns. Comparative genomic analysis of the Galphai1 gene between C. intestinalis and Ciona savignyi identified an 87-bp highly conserved non-coding sequence located between -3176 and -3090 bp upstream of the gene. Deletion of this conserved upstream sequence resulted in the complete loss of reporter expression in the central nervous system, while reporter expression in the adhesive organ and mesenchyme cells remained unaffected. The conserved upstream sequence can activate gene expression from basal promoters in the brain vesicle, although it requires additional cis-regulatory sequences to fully activate the CNS-specific gene expression. These results suggest that different types of central neurons share a common transcriptional activation mechanism that is different from that of papillar neurons.
Collapse
Affiliation(s)
- Reiko Yoshida
- Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako-gun, Hyogo 678-1297, Japan
| | | | | | | |
Collapse
|
36
|
Riyahi K, Shimeld SM. Chordate betagamma-crystallins and the evolutionary developmental biology of the vertebrate lens. Comp Biochem Physiol B Biochem Mol Biol 2007; 147:347-57. [PMID: 17493858 DOI: 10.1016/j.cbpb.2007.03.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2006] [Revised: 03/16/2007] [Accepted: 03/26/2007] [Indexed: 11/23/2022]
Abstract
Several animal lineages, including the vertebrates, have evolved sophisticated eyes with lenses that refract light to generate an image. The nearest invertebrate relatives of the vertebrates, such as the ascidians (sea squirts) and amphioxus, have only basic light detecting organs, leading to the widely-held view that the vertebrate lens is an innovation that evolved in early vertebrates. From an embryological perspective the lens is different from the rest of the eye, in that the eye is primarily of neural origin while the lens derives from a non-neural ectodermal placode which invaginates into the developing eye. How such an organ could have evolved has attracted much speculation. Recently, however, molecular developmental studies of sea squirts have started to suggest a possible evolutionary origin for the lens. First, studies of the Pax, Six, Eya and other gene families have indicated that sea squirts have areas of non-neural ectoderm homologous to placodes, suggesting an origin for the embryological characteristics of the lens. Second, the evolution and regulation of the betagamma-crystallins has been studied. These form one of the key crystallin gene families responsible for the transparency of the lens, and regulatory conservation between the betagamma-crystallin gene in the sea squirt Ciona intestinalis and the vertebrate visual system has been experimentally demonstrated. These data, together with knowledge of the morphological, physiological and gene expression similarities between the C. intestinalis ocellus and vertebrate retina, have led us to propose a hypothesis for the evolution of the vertebrate lens and integrated vertebrate eye via the co-option and combination of ancient gene regulatory networks; one controlling morphogenetic aspects of lens development and one controlling the expression of a gene family responsible for the biophysical properties of the lens, with the components of the retina having evolved from an ancestral photoreceptive organ derived from the anterior central nervous system.
Collapse
Affiliation(s)
- Kumars Riyahi
- Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
| | | |
Collapse
|
37
|
Marino R, Melillo D, Di Filippo M, Yamada A, Pinto MR, De Santis R, Brown ER, Matassi G. Ammonium channel expression is essential for brain development and function in the larva ofCiona intestinalis. J Comp Neurol 2007; 503:135-47. [PMID: 17480017 DOI: 10.1002/cne.21370] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Ammonium uptake into the cell is known to be mediated by ammonium transport (Amt) proteins, which are present in all domains of life. The physiological role of Amt proteins remains elusive; indeed, loss-of-function experiments suggested that Amt proteins do not play an essential role in bacteria, yeast, and plants. Here we show that the reverse holds true in the tunicate Ciona intestinalis. The genome of C. intestinalis contains two AMT genes, Ci-AMT1a and Ci-AMT1b, which we show derive from an ascidian-specific gene duplication. We analyzed Ci-AMT expression during embryo development. Notably, Ci-AMT1a is expressed in the larval brain in a small number of cells defining a previously unseen V-shaped territory; these cells connect the brain cavity to the external environment. We show that the knockdown of Ci-AMT1a impairs the formation of the brain cavity and consequently the function of the otolith, the gravity-sensing organ contained in it. We speculate that the normal mechanical functioning (flotation and free movement) of the otolith may require a close regulation of ammonium salt(s) concentration in the brain cavity, because ammonium is known to affect both fluid density and viscosity; the cells forming the V territory may act as a conduit in achieving such a regulation.
Collapse
Affiliation(s)
- Rita Marino
- Stazione Zoologica A Dohrn, Villa Comunale, Napoli, Italy
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Zega G, Thorndyke MC, Brown ER. Development of swimming behaviour in the larva of the ascidian Ciona intestinalis. ACTA ACUST UNITED AC 2006; 209:3405-12. [PMID: 16916975 DOI: 10.1242/jeb.02421] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of this study was to characterize the swimming behaviour of C. intestinalis larvae during the first 6 h after hatching by measuring tail muscle field potentials. This recording method allowed a quantitative description of the responses of the larva under light and dark conditions. Three different larval movements were distinguished by their specific frequencies: tail flicks, 'spontaneous' swimming, and shadow response, or dark induced activity, with respective mean frequencies of about 10, 22 and 32 Hz. The shadow response develops at about 1.5 h post hatching (h.p.h.). The frequency of muscle potentials associated with this behaviour became higher than those of spontaneous swimming activity, shifting from 20 to 30 Hz, but only from about 2 h.p.h. onwards. Swimming rate was influenced positively for about 25 s after the beginning of the shadow response. Comparison of swimming activity at three different larval ages (0-2, 2-4 and 4-6 h.p.h.) showed that Ciona larvae swim for longer periods and more frequently during the first hours after hatching. Our results provide a starting point for future studies that aim to characterize the nervous control of ascidian locomotion, in wild-type or mutant larvae.
Collapse
Affiliation(s)
- Giuliana Zega
- Neurobiology Laboratory Stazione Zoologica Anton Dohrn, Villa Comunale I-80121 Naples, Italy.
| | | | | |
Collapse
|
39
|
Shimeld SM, Purkiss AG, Dirks RPH, Bateman OA, Slingsby C, Lubsen NH. Urochordate betagamma-crystallin and the evolutionary origin of the vertebrate eye lens. Curr Biol 2006; 15:1684-9. [PMID: 16169492 DOI: 10.1016/j.cub.2005.08.046] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 08/05/2005] [Accepted: 08/09/2005] [Indexed: 11/22/2022]
Abstract
A refracting lens is a key component of our image-forming camera eye; however, its evolutionary origin is unknown because precursor structures appear absent in nonvertebrates. The vertebrate betagamma-crystallin genes encode abundant structural proteins critical for the function of the lens. We show that the urochordate Ciona intestinalis, which split from the vertebrate lineage before the evolution of the lens, has a single gene coding for a single domain monomeric betagamma-crystallin. The crystal structure of Ciona betagamma-crystallin is very similar to that of a vertebrate betagamma-crystallin domain, except for paired, occupied calcium binding sites. The Ciona betagamma-crystallin is only expressed in the palps and in the otolith, the pigmented sister cell of the light-sensing ocellus. The Ciona betagamma-crystallin promoter region targeted expression to the visual system, including lens, in transgenic Xenopus tadpoles. We conclude that the vertebrate betagamma-crystallins evolved from a single domain protein already expressed in the neuroectoderm of the prevertebrate ancestor. The conservation of the regulatory hierarchy controlling betagamma-crystallin expression between organisms with and without a lens shows that the evolutionary origin of the lens was based on co-option of pre-existing regulatory circuits controlling the expression of a key structural gene in a primitive light-sensing system.
Collapse
Affiliation(s)
- Sebastian M Shimeld
- Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom.
| | | | | | | | | | | |
Collapse
|
40
|
Abstract
Ascidians, or sea squirts, are lower chordates, and share basic gene repertoires and many characteristics, both developmental and physiological, with vertebrates. Therefore, decoding cis-regulatory systems in ascidians will contribute toward elucidating the genetic regulatory systems underlying the developmental and physiological processes of vertebrates. cis-Regulatory DNAs can also be used for tissue-specific genetic manipulation, a powerful tool for studying ascidian development and physiology. Because the ascidian genome is compact compared with vertebrate genomes, both intergenic regions and introns are relatively small in ascidians. Short upstream intergenic regions contain a complete set of cis-regulatory elements for spatially regulated expression of a majority of ascidian genes. These features of the ascidian genome are a great advantage in identifying cis-regulatory sequences and in analyzing their functions. Function of cis-regulatory DNAs has been analyzed for a number of tissue-specific and developmentally regulated genes of ascidians by introducing promoter-reporter fusion constructs into ascidian embryos. The availability of the whole genome sequences of the two Ciona species, Ciona intestinalis and Ciona savignyi, facilitates comparative genomics approaches to identify cis-regulatory DNAs. Recent studies demonstrate that computational methods can help identify cis-regulatory elements in the ascidian genome. This review presents a comprehensive list of ascidian genes whose cis-regulatory regions have been subjected to functional analysis, and highlights the recent advances in bioinformatics and comparative genomics approaches to cis-regulatory systems in ascidians.
Collapse
Affiliation(s)
- Takehiro Kusakabe
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Japan.
| |
Collapse
|
41
|
Jiang D, Tresser JW, Horie T, Tsuda M, Smith WC. Pigmentation in the sensory organs of the ascidian larva is essential for normal behavior. ACTA ACUST UNITED AC 2005; 208:433-8. [PMID: 15671331 DOI: 10.1242/jeb.01420] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Free-living animals and their larvae utilize light and gravity as cues to navigate in open space. Detection and response to these environmental stimuli are important for the dispersal and settlement of ascidian larvae. Two pigmented structures in the brain of the ascidian larva, the ocellus and the otolith, have been shown to function as the photoreceptive and gravity sensitive organs, respectively. Here, we show that pigmentation is essential for proper phototactic and geotactic behavior in larvae of the ascidian species Ciona savignyi. Two recessive and complementing mutant lines of C. savignyi, immaculate and spotless, that specifically disrupt the pigmentation of the sensory organs during larval development are described. Homozygous mutant larvae are unable to respond properly to gravity and illumination cues while settling. Genetic analysis shows that spotless is caused by a point mutation within the tyrosinase gene that creates a premature stop codon, while the molecular nature of immaculate is unknown. Although the role of pigmentation in the ocellus of C. savignyi is similar to that in vertebrate visual systems, our results demonstrate a novel use of melanin in geotactic behavior.
Collapse
Affiliation(s)
- Di Jiang
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, USA
| | | | | | | | | |
Collapse
|
42
|
Moret F, Christiaen L, Deyts C, Blin M, Vernier P, Joly JS. Regulatory gene expressions in the ascidian ventral sensory vesicle: evolutionary relationships with the vertebrate hypothalamus. Dev Biol 2005; 277:567-79. [PMID: 15617694 DOI: 10.1016/j.ydbio.2004.11.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/13/2004] [Accepted: 11/03/2004] [Indexed: 11/28/2022]
Abstract
In extant chordates, the overall patterning along the anteroposterior and dorsoventral axes of the neural tube is remarkably conserved. It has thus been proposed that four domains corresponding to the vertebrate presumptive forebrain, midbrain-hindbrain transition, hindbrain, and spinal cord were already present in the common chordate ancestor. To obtain insights on the evolution of the patterning of the anterior neural tube, we performed a study aimed at characterizing the expression of regulatory genes in the sensory vesicle of Ciona intestinalis, the anteriormost part of the central nervous system (CNS) related to the vertebrate forebrain, at tailbud stages. Selected genes encoded primarily for homologues of transcription factors involved in vertebrate forebrain patterning. Seven of these genes were expressed in the ventral sensory vesicle. A prominent feature of these ascidian genes is their restricted and complementary domains of expression at tailbud stages. These patterning markers thus refine the map of the developing sensory vesicle. Furthermore, they allow us to propose that a large part of the ventral and lateral sensory vesicle consists in a patterning domain corresponding to the vertebrate presumptive hypothalamus.
Collapse
Affiliation(s)
- Frédéric Moret
- Development, Evolution and Plasticity of the Nervous System, Institut de Neurobiologie Alfred Fessard, Centre National de la Recherche Scientifique, UPR2197, 1 ave de la terrasse, F-91198 Gif-sur-Yvette, France
| | | | | | | | | | | |
Collapse
|
43
|
Mazet F, Shimeld SM. Molecular evidence from ascidians for the evolutionary origin of vertebrate cranial sensory placodes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2005; 304:340-6. [PMID: 15981200 DOI: 10.1002/jez.b.21054] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cranial sensory placodes are specialised areas of the head ectoderm of vertebrate embryos that contribute to the formation of the cranial sense organs and associated ganglia. Placodes are often considered a vertebrate innovation, and their evolution has been hypothesised as one key adaptation underlying the evolution of active predation by primitive vertebrates. Here, we review recent molecular evidence pertinent to understanding the evolutionary origin of placodes. The development of vertebrate placodes is regulated by numerous genes, including members of the Pax, Six, Eya, Fox, Phox, Neurogenin and Pou gene families. In the sea squirt Ciona intestinalis (a basal chordate and close relative of the vertebrates), orthologues of these genes are deployed in the development of the oral and atrial siphons, structures used for filter feeding by the sessile adult. Our interpretation of these findings is that vertebrate placodes and sea squirt siphon primordia have evolved from the same patches of specialised ectoderm present in the common ancestor of the chordates.
Collapse
Affiliation(s)
- Francoise Mazet
- School of Animal and Microbial Sciences, University of Reading, UK
| | | |
Collapse
|