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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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Nydam ML, Saffo MB, Di Gregorio A. Women in tunicate research: Pioneers of the past and their present legacy. Genesis 2023; 61:e23578. [PMID: 38009445 DOI: 10.1002/dvg.23578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/05/2023] [Accepted: 11/06/2023] [Indexed: 11/28/2023]
Abstract
The search for female scientists who pioneered the research on tunicates is hindered by the tradition of reporting only the first initials of authors' names on scientific publications using only the initials of their first names. While this practice has the theoretical merit of broadening the readership by preventing the possible bias that could be caused by the gender of the author(s) in some of the readers, it rendered the identification of female researchers active in, or before, the first half of the 20th century quite challenging. Sifting through several dozen electronic records, and with the help of references and/or quotes found online, we have stitched together the information that we were able to retrieve on the life of female scientists who authored some of the earliest publications on tunicates, and we have organized them in (approximate) chronological order. We have also compiled brief synopses of the findings of scientists active in the field of tunicate biology in more recent times, and organized them by subdiscipline.
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Affiliation(s)
- Marie L Nydam
- Life Sciences Concentration, Soka University of America, Aliso Viejo, California, USA
| | | | - Anna Di Gregorio
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, New York, USA
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Konishi M, Kishi K, Morita R, Yamada A, Onuma TA, Nishida H. Formation of the brain by stem cell divisions of large neuroblasts in Oikopleura dioica, a simple chordate. Dev Genes Evol 2023:10.1007/s00427-023-00704-y. [PMID: 37231211 DOI: 10.1007/s00427-023-00704-y] [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: 01/13/2023] [Accepted: 05/04/2023] [Indexed: 05/27/2023]
Abstract
Stem cell division contributes to the generation of various cell types during animal development, especially a diverse pool of neural cells in the nervous system. One example is reiterated unequal stem cell divisions, in which a large stem cell undergoes a series of oriented unequal divisions to produce a chain of small daughter cells that differentiate. We show that reiterated unequal stem cell divisions are involved in the formation of the brain in simple chordate appendicularians (larvaceans). Two large neuroblasts in the anterior and middle of the brain-forming region of hatched larvae were observed. They produced at least 30 neural cells out of 96 total brain cells before completion of brain formation at 10 hours after fertilization by reiterated unequal stem cell divisions. The daughter cells of the anterior neuroblast were postmitotic, and the number was at least 19. The neuroblast produced small daughter neural cells posteriorly every 20 min. The neural cells first moved toward the dorsal side, turned in the anterior direction, aligned in a single line according to their birth order, and showed collective movement to accumulate in the anterior part of the brain. The anterior neuroblast originated from the right-anterior blastomeres of the eight-cell embryos and the right a222 blastomere of the 64-cell embryo. The posterior neuroblast also showed reiterated unequal stem cell divisions, and generated at least 11 neural cells. Sequential unequal stem cell divisions without stem cell growth have been observed in protostomes, such as insects and annelids. The results provide the first examples of this kind of stem cell division during brain formation in non-vertebrate deuterostomes.
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Affiliation(s)
- Misako Konishi
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Kanae Kishi
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Ryo Morita
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Atsuko Yamada
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Takeshi A Onuma
- Faculty of Science, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan.
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Kim K, Orvis J, Stolfi A. Pax3/7 regulates neural tube closure and patterning in a non-vertebrate chordate. Front Cell Dev Biol 2022; 10:999511. [PMID: 36172287 PMCID: PMC9511217 DOI: 10.3389/fcell.2022.999511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 08/24/2022] [Indexed: 11/29/2022] Open
Abstract
Pax3/7 factors play numerous roles in the development of the dorsal nervous system of vertebrates. From specifying neural crest at the neural plate borders, to regulating neural tube closure and patterning of the resulting neural tube. However, it is unclear which of these roles are conserved in non-vertebrate chordates. Here we investigate the expression and function of Pax3/7 in the model tunicate Ciona. Pax3/7 is expressed in neural plate border cells during neurulation, and in central nervous system progenitors shortly after neural tube closure. We find that separate cis-regulatory elements control the expression in these two distinct lineages. Using CRISPR/Cas9-mediated mutagenesis, we knocked out Pax3/7 in F0 embryos specifically in these two separate territories. Pax3/7 knockout in the neural plate borders resulted in neural tube closure defects, suggesting an ancient role for Pax3/7 in this chordate-specific process. Furthermore, knocking out Pax3/7 in the neural impaired Motor Ganglion neuron specification, confirming a conserved role for this gene in patterning the neural tube as well. Taken together, these results suggests that key functions of Pax3/7 in neural tube development are evolutionarily ancient, dating back at least to the last common ancestor of vertebrates and tunicates.
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Popsuj S, Stolfi A. Ebf Activates Expression of a Cholinergic Locus in a Multipolar Motor Ganglion Interneuron Subtype in Ciona. Front Neurosci 2022; 15:784649. [PMID: 34975385 PMCID: PMC8719597 DOI: 10.3389/fnins.2021.784649] [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: 09/28/2021] [Accepted: 11/30/2021] [Indexed: 11/13/2022] Open
Abstract
Conserved transcription factors termed “terminal selectors” regulate neuronal sub-type specification and differentiation through combinatorial transcriptional regulation of terminal differentiation genes. The unique combinations of terminal differentiation gene products in turn contribute to the functional identities of each neuron. One well-characterized terminal selector is COE (Collier/Olf/Ebf), which has been shown to activate cholinergic gene batteries in C. elegans motor neurons. However, its functions in other metazoans, particularly chordates, is less clear. Here we show that the sole COE ortholog in the non-vertebrate chordate Ciona robusta, Ebf, controls the expression of the cholinergic locus VAChT/ChAT in a single dorsal interneuron of the larval Motor Ganglion, which is presumed to be homologous to the vertebrate spinal cord. We propose that, while the function of Ebf as a regulator of cholinergic neuron identity conserved across bilaterians, its exact role may have diverged in different cholinergic neuron subtypes (e.g., interneurons vs. motor neurons) in chordate-specific motor circuits.
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Affiliation(s)
- Sydney Popsuj
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
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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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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.
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Affiliation(s)
- Paola Olivo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonio Palladino
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Filomena Ristoratore
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Antonietta Spagnuolo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
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8
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Mechanics of neural tube morphogenesis. Semin Cell Dev Biol 2021; 130:56-69. [PMID: 34561169 DOI: 10.1016/j.semcdb.2021.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 09/07/2021] [Accepted: 09/10/2021] [Indexed: 01/07/2023]
Abstract
The neural tube is an important model system of morphogenesis representing the developmental module of out-of-plane epithelial deformation. As the embryonic precursor of the central nervous system, the neural tube also holds keys to many defects and diseases. Recent advances begin to reveal how genetic, cellular and environmental mechanisms work in concert to ensure correct neural tube shape. A physical model is emerging where these factors converge at the regulation of the mechanical forces and properties within and around the tissue that drive tube formation towards completion. Here we review the dynamics and mechanics of neural tube morphogenesis and discuss the underlying cellular behaviours from the viewpoint of tissue mechanics. We will also highlight some of the conceptual and technical next steps.
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Borba C, Kourakis MJ, Schwennicke S, Brasnic L, Smith WC. Fold Change Detection in Visual Processing. Front Neural Circuits 2021; 15:705161. [PMID: 34497492 PMCID: PMC8419522 DOI: 10.3389/fncir.2021.705161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
Visual processing transforms the complexities of the visual world into useful information. Ciona, an invertebrate chordate and close relative of the vertebrates, has one of the simplest nervous systems known, yet has a range of visuomotor behaviors. This simplicity has facilitated studies linking behavior and neural circuitry. Ciona larvae have two distinct visuomotor behaviors - a looming shadow response and negative phototaxis. These are mediated by separate neural circuits that initiate from different clusters of photoreceptors, with both projecting to a CNS structure called the posterior brain vesicle (pBV). We report here that inputs from both circuits are processed to generate fold change detection (FCD) outputs. In FCD, the behavioral response scales with the relative fold change in input, but is invariant to the overall magnitude of the stimulus. Moreover, the two visuomotor behaviors have fundamentally different stimulus/response relationships - indicative of differing circuit strategies, with the looming shadow response showing a power relationship to fold change, while the navigation behavior responds linearly. Pharmacological modulation of the FCD response points to the FCD circuits lying outside of the visual organ (the ocellus), with the pBV being the most likely location. Consistent with these observations, the connectivity and properties of pBV interneurons conform to known FCD circuit motifs, but with different circuit architectures for the two circuits. The negative phototaxis circuit forms a putative incoherent feedforward loop that involves interconnecting cholinergic and GABAergic interneurons. The looming shadow circuit uses the same cholinergic and GABAergic interneurons, but with different synaptic inputs to create a putative non-linear integral feedback loop. These differing circuit architectures are consistent with the behavioral outputs of the two circuits. Finally, while some reports have highlighted parallels between the pBV and the vertebrate midbrain, suggesting a common origin for the two, others reports have disputed this, suggesting that invertebrate chordates lack a midbrain homolog. The convergence of visual inputs at the pBV, and its putative role in visual processing reported here and in previous publications, lends further support to the proposed common origin of the pBV and the vertebrate midbrain.
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Affiliation(s)
- Cezar Borba
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Matthew J Kourakis
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Shea Schwennicke
- College of Creative Studies, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Lorena Brasnic
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States.,Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - William C Smith
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States.,College of Creative Studies, University of California, Santa Barbara, Santa Barbara, CA, United States
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Winkley KM, Reeves WM, Veeman MT. Single-cell analysis of cell fate bifurcation in the chordate Ciona. BMC Biol 2021; 19:180. [PMID: 34465302 PMCID: PMC8408944 DOI: 10.1186/s12915-021-01122-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/12/2021] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Inductive signaling interactions between different cell types are a major mechanism for the further diversification of embryonic cell fates. Most blastomeres in the model chordate Ciona robusta become restricted to a single predominant fate between the 64-cell and mid-gastrula stages. The deeply stereotyped and well-characterized Ciona embryonic cell lineages allow the transcriptomic analysis of newly established cell types very early in their divergence from sibling cell states without the pseudotime inference needed in the analysis of less synchronized cell populations. This is the first ascidian study to use droplet scRNAseq with large numbers of analyzed cells as early as the 64-cell stage when major lineages such as primary notochord first become fate restricted. RESULTS AND CONCLUSIONS We identify 59 distinct cell states, including new subregions of the b-line neural lineage and the early induction of the tail tip epidermis. We find that 34 of these cell states are directly or indirectly dependent on MAPK-mediated signaling critical to early Ciona patterning. Most of the MAPK-dependent bifurcations are canalized with the signal-induced cell fate lost upon MAPK inhibition, but the posterior endoderm is unique in being transformed into a novel state expressing some but not all markers of both endoderm and muscle. Divergent gene expression between newly bifurcated sibling cell types is dominated by upregulation in the induced cell type. The Ets family transcription factor Elk1/3/4 is uniquely upregulated in nearly all the putatively direct inductions. Elk1/3/4 upregulation together with Ets transcription factor binding site enrichment analysis enables inferences about which bifurcations are directly versus indirectly controlled by MAPK signaling. We examine notochord induction in detail and find that the transition between a Zic/Ets-mediated regulatory state and a Brachyury/FoxA-mediated regulatory state is unexpectedly late. This supports a "broad-hourglass" model of cell fate specification in which many early tissue-specific genes are induced in parallel to key tissue-specific transcriptional regulators via the same set of transcriptional inputs.
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Affiliation(s)
- Konner M Winkley
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Wendy M Reeves
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Michael T Veeman
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA.
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Smith HM, Khairallah SM, Nguyen AH, Newman-Smith E, Smith WC. Misregulation of cell adhesion molecules in the Ciona neural tube closure mutant bugeye. Dev Biol 2021; 480:14-24. [PMID: 34407458 DOI: 10.1016/j.ydbio.2021.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 07/16/2021] [Accepted: 08/10/2021] [Indexed: 11/18/2022]
Abstract
Neural tube closure (NTC) is a complex multi-step morphogenetic process that transforms the flat neural plate found on the surface of the post-gastrulation embryo into the hollow and subsurface central nervous system (CNS). Errors in this process underlie some of the most prevalent human birth defects, and occur in about 1 out of every 1000 births. Previously, we discovered a mutant in the basal chordate Ciona savignyi (named bugeye) that revealed a novel role for a T-Type Calcium Channel (Cav3) in this process. Moreover, the requirement for CAV3s in Xenopus NTC suggests a conserved function among the chordates. Loss of CAV3 leads to defects restricted to anterior NTC, with the brain apparently fully developed, but protruding from the head. Here we report first on a new Cav3 mutant in the related species C. robusta. RNAseq analysis of both C. robusta and C. savignyi bugeye mutants reveals misregulation of a number of transcripts including ones that are involved in cell-cell recognition and adhesion. Two in particular, Selectin and Fibronectin leucine-rich repeat transmembrane, which are aberrantly upregulated in the mutant, are expressed in the closing neural tube, and when disrupted by CRISPR gene editing lead to the open brain phenotype displayed in bugeye mutants. We speculate that these molecules play a transient role in tissue separation and adhesion during NTC and failure to downregulate them leads to an open neural tube.
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Affiliation(s)
- Haley M Smith
- Department of Molecular, Cellular and Developmental Biology, USA
| | | | - Ann Hong Nguyen
- Department of Molecular, Cellular and Developmental Biology, USA
| | | | - William C Smith
- Department of Molecular, Cellular and Developmental Biology, USA; Neuroscience Research Institute, University of California, Santa Barbara, CA, 93106, USA.
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12
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Oonuma K, Kusakabe TG. The complete cell lineage and MAPK- and Otx-dependent specification of the dopaminergic cells in the Ciona brain. Development 2021; 148:269114. [PMID: 34121117 DOI: 10.1242/dev.198754] [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: 11/17/2020] [Accepted: 05/17/2021] [Indexed: 11/20/2022]
Abstract
The Ciona larva has served as a unique model for understanding the development of dopaminergic cells at single-cell resolution owing to the exceptionally small number of neurons in its brain and its fixed cell lineage during embryogenesis. A recent study suggested that the transcription factors Fer2 and Meis directly regulate the dopamine synthesis genes in Ciona, but the dopaminergic cell lineage and the gene regulatory networks that control the development of dopaminergic cells have not been fully elucidated. Here, we reveal that the dopaminergic cells in Ciona are derived from a bilateral pair of cells called a9.37 cells at the center of the neural plate. The a9.37 cells divide along the anterior-posterior axis, and all of the descendants of the posterior daughter cells differentiate into the dopaminergic cells. We show that the MAPK pathway and the transcription factor Otx are required for the expression of Fer2 in the dopaminergic cell lineage. Our findings establish the cellular and molecular framework for fully understanding the commitment to dopaminergic cells in the simple chordate brain.
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Affiliation(s)
- Kouhei Oonuma
- Institute for Integrative Neurobiology and Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
| | - Takehiro G Kusakabe
- Institute for Integrative Neurobiology and Department of Biology, Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
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13
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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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14
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Lowe EK, Racioppi C, Peyriéras N, Ristoratore F, Christiaen L, Swalla BJ, Stolfi A. A cis-regulatory change underlying the motor neuron-specific loss of Ebf expression in immotile tunicate larvae. Evol Dev 2021; 23:72-85. [PMID: 33355999 PMCID: PMC7920938 DOI: 10.1111/ede.12364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 10/23/2020] [Accepted: 12/06/2020] [Indexed: 11/26/2022]
Abstract
Many species in the tunicate family Molgulidae have independently lost their swimming larval form and instead develop as tailless, immotile larvae. These larvae do not develop structures that are essential for swimming such as the notochord, otolith, and tail muscles. However, little is known about neural development in these nonswimming larvae. Here, we studied the patterning of the Motor Ganglion (MG) of Molgula occulta, a nonswimming species. We found that spatial patterns of MG neuron regulators in this species are conserved, compared with species with swimming larvae, suggesting that the gene networks regulating their expression are intact despite the loss of swimming. However, expression of the key motor neuron regulatory gene Ebf (Collier/Olf/EBF) was reduced in the developing MG of M. occulta when compared with molgulid species with swimming larvae. This was corroborated by measuring allele-specific expression of Ebf in hybrid embryos from crosses of M. occulta with the swimming species M. oculata. Heterologous reporter construct assays in the model tunicate species Ciona robusta revealed a specific cis-regulatory sequence change that reduces expression of Ebf in the MG, but not in other cells. Taken together, these data suggest that MG neurons are still specified in M. occulta larvae, but their differentiation might be impaired due to reduction of Ebf expression levels.
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Affiliation(s)
- Elijah K. Lowe
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Station Biologique de Roscoff, Roscoff, France
| | - Claudia Racioppi
- Station Biologique de Roscoff, Roscoff, France
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, USA
| | - Nadine Peyriéras
- Station Biologique de Roscoff, Roscoff, France
- UPS3611 Complex Systems Institute Paris Ile-de-France (ISC-PIF), CNRS, Paris, France
- USR3695 BioEmergences, CNRS, Paris-Saclay University, Gif-sur-Yvette, France
| | - Filomena Ristoratore
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Lionel Christiaen
- Station Biologique de Roscoff, Roscoff, France
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY, USA
| | - Billie J. Swalla
- Station Biologique de Roscoff, Roscoff, France
- Department of Biology, University of Washington, Seattle, WA, USA
- Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
- Station Biologique de Roscoff, Roscoff, France
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15
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Abstract
For centuries, the eye has fascinated scientists and philosophers alike, and as a result the visual system has always been at the forefront of integrating cutting-edge technology in research. We are again at a turning point at which technical advances have expanded the range of organisms we can study developmentally and deepened what we can learn. In this new era, we are finally able to understand eye development in animals across the phylogenetic tree. In this Review, we highlight six areas in comparative visual system development that address questions that are important for understanding the developmental basis of evolutionary change. We focus on the opportunities now available to biologists to study the developmental genetics, cell biology and morphogenesis that underlie the incredible variation of visual organs found across the Metazoa. Although decades of important work focused on gene expression has suggested homologies and potential evolutionary relationships between the eyes of diverse animals, it is time for developmental biologists to move away from this reductive approach. We now have the opportunity to celebrate the differences and diversity in visual organs found across animal development, and to learn what it can teach us about the fundamental principles of biological systems and how they are built.
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Affiliation(s)
- Kristen M Koenig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- John Harvard Distinguished Science Fellowship Program, Harvard University, Cambridge, MA 02138, USA
| | - Jeffrey M Gross
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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16
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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.
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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
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17
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Guignard L, Fiúza UM, Leggio B, Laussu J, Faure E, Michelin G, Biasuz K, Hufnagel L, Malandain G, Godin C, Lemaire P. Contact area-dependent cell communication and the morphological invariance of ascidian embryogenesis. Science 2020; 369:369/6500/eaar5663. [PMID: 32646972 DOI: 10.1126/science.aar5663] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 04/29/2020] [Indexed: 12/18/2022]
Abstract
Marine invertebrate ascidians display embryonic reproducibility: Their early embryonic cell lineages are considered invariant and are conserved between distantly related species, despite rapid genomic divergence. Here, we address the drivers of this reproducibility. We used light-sheet imaging and automated cell segmentation and tracking procedures to systematically quantify the behavior of individual cells every 2 minutes during Phallusia mammillata embryogenesis. Interindividual reproducibility was observed down to the area of individual cell contacts. We found tight links between the reproducibility of embryonic geometries and asymmetric cell divisions, controlled by differential sister cell inductions. We combined modeling and experimental manipulations to show that the area of contact between signaling and responding cells is a key determinant of cell communication. Our work establishes the geometric control of embryonic inductions as an alternative to classical morphogen gradients and suggests that the range of cell signaling sets the scale at which embryonic reproducibility is observed.
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Affiliation(s)
- Léo Guignard
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France.,Virtual Plants, Université de Montpellier, CIRAD, INRA, Inria, 34095 Montpellier, France.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Ulla-Maj Fiúza
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Bruno Leggio
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France.,Virtual Plants, Université de Montpellier, CIRAD, INRA, Inria, 34095 Montpellier, France.,Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Inria, 69342 Lyon, France
| | - Julien Laussu
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Emmanuel Faure
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France.,Virtual Plants, Université de Montpellier, CIRAD, INRA, Inria, 34095 Montpellier, France.,Institut de Recherche en Informatique de Toulouse (IRIT), Universités Toulouse I et III, CNRS, INPT, ENSEEIHT, 31071 Toulouse, France
| | - Gaël Michelin
- Morpheme, Université Côte d'Azur, Inria, CNRS, I3S, France
| | - Kilian Biasuz
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France
| | - Lars Hufnagel
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
| | | | - Christophe Godin
- Virtual Plants, Université de Montpellier, CIRAD, INRA, Inria, 34095 Montpellier, France. .,Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Inria, 69342 Lyon, France
| | - Patrick Lemaire
- CRBM, Université de Montpellier, CNRS, 34293 Montpellier, France.
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18
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Gibboney S, Orvis J, Kim K, Johnson CJ, Martinez-Feduchi P, Lowe EK, Sharma S, Stolfi A. Effector gene expression underlying neuron subtype-specific traits in the Motor Ganglion of Ciona. Dev Biol 2020; 458:52-63. [PMID: 31639337 PMCID: PMC6987015 DOI: 10.1016/j.ydbio.2019.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 10/11/2019] [Accepted: 10/16/2019] [Indexed: 12/31/2022]
Abstract
The central nervous system of the Ciona larva contains only 177 neurons. The precise regulation of neuron subtype-specific morphogenesis and differentiation observed during the formation of this minimal connectome offers a unique opportunity to dissect gene regulatory networks underlying chordate neurodevelopment. Here we compare the transcriptomes of two very distinct neuron types in the hindbrain/spinal cord homolog of Ciona, the Motor Ganglion (MG): the Descending decussating neuron (ddN, proposed homolog of Mauthner Cells in vertebrates) and the MG Interneuron 2 (MGIN2). Both types are invariantly represented by a single bilaterally symmetric left/right pair of cells in every larva. Supernumerary ddNs and MGIN2s were generated in synchronized embryos and isolated by fluorescence-activated cell sorting for transcriptome profiling. Differential gene expression analysis revealed ddN- and MGIN2-specific enrichment of a wide range of genes, including many encoding potential "effectors" of subtype-specific morphological and functional traits. More specifically, we identified the upregulation of centrosome-associated, microtubule-stabilizing/bundling proteins and extracellular guidance cues part of a single intrinsic regulatory program that might underlie the unique polarization of the ddNs, the only descending MG neurons that cross the midline. Consistent with our predictions, CRISPR/Cas9-mediated, tissue-specific elimination of two such candidate effectors, Efcab6-related and Netrin1, impaired ddN polarized axon outgrowth across the midline.
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Affiliation(s)
- Susanne Gibboney
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Jameson Orvis
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Kwantae Kim
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Christopher J Johnson
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | | | - Elijah K Lowe
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Sarthak Sharma
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
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19
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Bueno D, Parvas M, Nabiuni M, Miyan J. Embryonic cerebrospinal fluid formation and regulation. Semin Cell Dev Biol 2019; 102:3-12. [PMID: 31615690 DOI: 10.1016/j.semcdb.2019.09.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/10/2019] [Accepted: 09/12/2019] [Indexed: 01/01/2023]
Abstract
The vertebrate brain is organized, from its embryonic origin and throughout adult life, around a dynamic and complex fluid, the cerebrospinal fluid (CSF). There is growing interest in the composition, dynamics and function of the CSF in brain development research. It has been demonstrated in higher vertebrates that CSF has key functions in delivering diffusible signals and nutrients to the developing brain, contributing to the proliferation, differentiation and survival of neural progenitor cells, and to the patterning of the brain. It has also been shown that the composition and the homeostasis of CSF are tightly regulated following the closure of the anterior neuropore, just before the initiation of primary neurogenesis in the neural tissue surrounding brain cavities, before the formation of functional choroid plexus. In this review we draw together existing literature about the composition and formation of embryonic cerebrospinal fluid in birds and mammals, from the closure of the anterior neuropore to the formation of functional fetal choroid plexus, including mechanisms regulating its composition and homeostasis. The significance of CSF regulation within embryonic brain is also discussed from an evolutionary perspective.
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Affiliation(s)
- David Bueno
- Section of Biomedical, Evolutionary and Developmental Genetics, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Av. Diagonal 643. Barcelona 08028, Catalonia Spain.
| | - Maryam Parvas
- Section of Biomedical, Evolutionary and Developmental Genetics, Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Av. Diagonal 643. Barcelona 08028, Catalonia Spain
| | - Mohammad Nabiuni
- Division of Neuroscience & Experimental Psychology, Faculty of Biology, Medicine & Health, The University of Manchester, Stopford Building, Oxford Road. Manchester M13 9PT, UK
| | - Jaleel Miyan
- Division of Neuroscience & Experimental Psychology, Faculty of Biology, Medicine & Health, The University of Manchester, Stopford Building, Oxford Road. Manchester M13 9PT, UK
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20
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Winkley K, Ward S, Reeves W, Veeman M. Iterative and Complex Asymmetric Divisions Control Cell Volume Differences in Ciona Notochord Tapering. Curr Biol 2019; 29:3466-3477.e4. [PMID: 31607534 DOI: 10.1016/j.cub.2019.08.056] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/29/2019] [Accepted: 08/21/2019] [Indexed: 12/12/2022]
Abstract
The notochord of the invertebrate chordate Ciona forms a tapered rod at tailbud stages consisting of only 40 cylindrical cells in a single-file column. This tapered shape involves differences in notochord cell volume along the anterior-posterior axis. Here, we quantify sibling cell volume asymmetry throughout the developing notochord and find that there are distinctive patterns of unequal cleavage in all 4 bilateral pairs of A-line primary notochord founder cells and also in the B-line-derived secondary notochord founder cells. A quantitative model confirms that the observed patterns of unequal cleavage are sufficient to explain all the anterior-posterior variation in notochord cell volume. Many examples are known of cells that divide asymmetrically to give daughter cells of different size and fate. Here, by contrast, a series of subtle but iterative and finely patterned asymmetric divisions controls the shape of an entire organ. Quantitative 3D analysis of cell shape and spindle positioning allows us to infer multiple cellular mechanisms driving these unequal cleavages, including polarized displacements of the mitotic spindle, contributions from the shape of the mother cell, and late changes occurring between anaphase and abscission that potentially involve differential cortical contractility. We infer differential use of these mechanisms between different notochord blastomeres and also between different rounds of cell division. These results demonstrate a new role for asymmetric division in directly shaping a developing organ and point toward complex underlying mechanisms.
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Affiliation(s)
- Konner Winkley
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, KS 66506, USA
| | - Spencer Ward
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, KS 66506, USA
| | - Wendy Reeves
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, KS 66506, USA
| | - Michael Veeman
- Division of Biology, Kansas State University, 1717 Claflin Road, Manhattan, KS 66506, USA.
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21
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Sharma S, Wang W, Stolfi A. Single-cell transcriptome profiling of the Ciona larval brain. Dev Biol 2019; 448:226-236. [PMID: 30392840 PMCID: PMC6487232 DOI: 10.1016/j.ydbio.2018.09.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/10/2018] [Accepted: 09/10/2018] [Indexed: 11/27/2022]
Abstract
The tadpole-type larva of Ciona has emerged as an intriguing model system for the study of neurodevelopment. The Ciona intestinalis connectome has been recently mapped, revealing the smallest central nervous system (CNS) known in any chordate, with only 177 neurons. This minimal CNS is highly reminiscent of larger CNS of vertebrates, sharing many conserved developmental processes, anatomical compartments, neuron subtypes, and even specific neural circuits. Thus, the Ciona tadpole offers a unique opportunity to understand the development and wiring of a chordate CNS at single-cell resolution. Here we report the use of single-cell RNAseq to profile the transcriptomes of single cells isolated by fluorescence-activated cell sorting (FACS) from the whole brain of Ciona robusta (formerly intestinalis Type A) larvae. We have also compared these profiles to bulk RNAseq data from specific subsets of brain cells isolated by FACS using cell type-specific reporter plasmid expression. Taken together, these datasets have begun to reveal the compartment- and cell-specific gene expression patterns that define the organization of the Ciona larval brain.
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Affiliation(s)
- Sarthak Sharma
- Georgia Institute of Technology, School of Biological Sciences, Atlanta, GA, United States
| | - Wei Wang
- New York University, Department of Biology, New York, NY, United States
| | - Alberto Stolfi
- Georgia Institute of Technology, School of Biological Sciences, Atlanta, GA, United States.
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22
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Transcriptional regulation of the Ciona Gsx gene in the neural plate. Dev Biol 2018; 448:88-100. [PMID: 30583796 DOI: 10.1016/j.ydbio.2018.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/06/2018] [Accepted: 12/11/2018] [Indexed: 12/29/2022]
Abstract
The ascidian neural plate consists of a defined number of identifiable cells organized in a grid of rows and columns, representing a useful model to investigate the molecular mechanisms controlling neural patterning in chordates. Distinct anterior brain lineages are specified via unique combinatorial inputs of signalling pathways with Nodal and Delta-Notch signals patterning along the medial-lateral axis and FGF/MEK/ERK signals patterning along the anterior-posterior axis of the neural plate. The Ciona Gsx gene is specifically expressed in the a9.33 cells in the row III/column 2 position of anterior brain lineages, characterised by a combinatorial input of Nodal-OFF, Notch-ON and FGF-ON. Here, we identify the minimal cis-regulatory element (CRE) of 376 bp, which can recapitulate the early activation of Gsx. We show that this minimal CRE responds in the same way as the endogenous Gsx gene to manipulation of FGF- and Notch-signalling pathways and to overexpression of Snail, a mediator of Nodal signals, and Six3/6, which is required to demarcate the anterior boundary of Gsx expression at the late neurula stage. We reveal that sequences proximal to the transcription start site include a temporal regulatory element required for the precise transcriptional onset of gene expression. We conclude that sufficient spatial and temporal information for Gsx expression is integrated in 376 bp of non-coding cis-regulatory sequences.
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23
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Lowe EK, Stolfi A. Developmental system drift in motor ganglion patterning between distantly related tunicates. EvoDevo 2018; 9:18. [PMID: 30062003 PMCID: PMC6057086 DOI: 10.1186/s13227-018-0107-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/18/2018] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The larval nervous system of the solitary tunicate Ciona is a simple model for the study of chordate neurodevelopment. The development and connectivity of the Ciona motor ganglion have been studied in fine detail, but how this important structure develops in other tunicates is not well known. METHODS AND RESULTS By comparing gene expression patterns in the developing MG of the distantly related tunicate Molgula occidentalis, we found that its patterning is highly conserved compared to the Ciona MG. MG neuronal subtypes in Molgula were specified in the exact same positions as in Ciona, though the timing of subtype-specific gene expression onset was slightly shifted to begin earlier, relative to mitotic exit and differentiation. In transgenic Molgula embryos electroporated with Dmbx reporter plasmids, we were also able to characterize the morphology of the lone pair of descending decussating neurons (ddNs) in Molgula, revealing the same unique contralateral projection seen in Ciona ddNs and their putative vertebrate homologs the Mauthner cells. Although Dmbx expression labels the ddNs in both species, cross-species transgenic assays revealed significant changes to the regulatory logic underlying Dmbx transcription. We found that Dmbx cis-regulatory DNAs from Ciona can drive highly specific reporter gene expression in Molgula ddNs, but Molgula sequences are not active in Ciona ddNs. CONCLUSIONS This acute divergence in the molecular mechanisms that underlie otherwise functionally conserved cis-regulatory DNAs supports the recently proposed idea that the extreme genetic plasticity observed in tunicates may be attributed to the extreme rigidity of the spatial organization of their embryonic cell lineages.
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Affiliation(s)
- Elijah K. Lowe
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA USA
| | - Alberto Stolfi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA USA
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24
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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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25
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Salvador-Martínez I, Salazar-Ciudad I. How complexity increases in development: An analysis of the spatial-temporal dynamics of Gene expression in Ciona intestinalis. Mech Dev 2017; 144:113-124. [PMID: 28189795 DOI: 10.1016/j.mod.2017.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 02/04/2017] [Accepted: 02/06/2017] [Indexed: 12/11/2022]
Abstract
The increase in complexity in an embryo over developmental time is perhaps one of the most intuitive processes of animal development. It is also intuitive that the embryo becomes progressively compartmentalized over time and space. In spite of this intuitiveness, there are no systematic attempts to quantify how this occurs. Here, we present a quantitative analysis of the compartmentalization and spatial complexity of Ciona intestinalis over developmental time by analyzing thousands of gene expression spatial patterns from the ANISEED database. We measure compartmentalization in two ways: as the relative volume of expression of genes and as the disparity in gene expression between body parts. We also use a measure of the curvature of each gene expression pattern in 3D space. These measures show a similar increase over time, with the most dramatic change occurring from the 112-cell stage to the early tailbud stage. Combined, these measures point to a global pattern of increase in complexity in the Ciona embryo. Finally, we cluster the different regions of the embryo depending on their gene expression similarity, within and between stages. Results from this clustering analysis, which partially correspond to known fate maps, provide a global quantitative overview about differentiation and compartmentalization between body parts at each developmental stage.
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Affiliation(s)
- Irepan Salvador-Martínez
- Evo-devo Helsinki community, Center of Excellence in Experimental Computational Developmental Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Isaac Salazar-Ciudad
- Evo-devo Helsinki community, Center of Excellence in Experimental Computational Developmental Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland; Genomics, Bioinformatics and Evolution, Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, Barcelona, Spain.
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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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Esposito R, Yasuo H, Sirour C, Palladino A, Spagnuolo A, Hudson C. Patterning of brain precursors in ascidian embryos. Development 2016; 144:258-264. [PMID: 27993985 DOI: 10.1242/dev.142307] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/02/2016] [Indexed: 11/20/2022]
Abstract
In terms of their embryonic origins, the anterior and posterior parts of the ascidian central nervous system (CNS) are associated with distinct germ layers. The anterior part of the sensory vesicle, or brain, originates from ectoderm lineages following a neuro-epidermal binary fate decision. In contrast, a large part of the remaining posterior CNS is generated following neuro-mesodermal binary fate decisions. Here, we address the mechanisms that pattern the anterior brain precursors along the medial-lateral axis (future ventral-dorsal) at neural plate stages. Our functional studies show that Nodal signals are required for induction of lateral genes, including Delta-like, Snail, Msxb and Trp Delta-like/Notch signalling induces intermediate (Gsx) over medial (Meis) gene expression in intermediate cells, whereas the combinatorial action of Snail and Msxb prevents the expression of Gsx in lateral cells. We conclude that despite the distinct embryonic lineage origins within the larval CNS, the mechanisms that pattern neural precursors are remarkably similar.
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Affiliation(s)
- Rosaria Esposito
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy
| | - Hitoyoshi Yasuo
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France
| | - Cathy Sirour
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France
| | - Antonio Palladino
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy
| | - Antonietta Spagnuolo
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli 80121, Italy
| | - Clare Hudson
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, Villefranche-sur-mer 06230, France
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28
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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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29
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Navarrete IA, Levine M. Nodal and FGF coordinate ascidian neural tube morphogenesis. Development 2016; 143:4665-4675. [PMID: 27827820 DOI: 10.1242/dev.144733] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 10/21/2016] [Indexed: 01/06/2023]
Abstract
Formation of the vertebrate neural tube represents one of the premier examples of morphogenesis in animal development. Here, we investigate this process in the simple chordate Ciona intestinalis Previous studies have implicated Nodal and FGF signals in the specification of lateral and ventral neural progenitors. We show that these signals also control the detailed cellular behaviors underlying morphogenesis of the neural tube. Live-imaging experiments show that FGF controls the intercalary movements of ventral neural progenitors, whereas Nodal is essential for the characteristic stacking behavior of lateral cells. Ectopic activation of FGF signaling is sufficient to induce intercalary behaviors in cells that have not received Nodal. In the absence of FGF and Nodal, neural progenitors exhibit a default behavior of sequential cell divisions, and fail to undergo the intercalary and stacking behaviors essential for normal morphogenesis. Thus, cell specification events occurring prior to completion of gastrulation coordinate the morphogenetic movements underlying the organization of the neural tube.
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Affiliation(s)
- Ignacio A Navarrete
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development, University of California, Berkeley, CA 94720, USA
| | - Michael Levine
- Department of Molecular and Cell Biology, Division of Genetics, Genomics and Development, University of California, Berkeley, CA 94720, USA
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Oonuma K, Tanaka M, Nishitsuji K, Kato Y, Shimai K, Kusakabe TG. Revised lineage of larval photoreceptor cells in Ciona reveals archetypal collaboration between neural tube and neural crest in sensory organ formation. Dev Biol 2016; 420:178-185. [PMID: 27789227 DOI: 10.1016/j.ydbio.2016.10.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 10/23/2016] [Accepted: 10/23/2016] [Indexed: 01/20/2023]
Abstract
The Ciona intestinalis larva has two distinct photoreceptor organs, a conventional pigmented ocellus and a nonpigmented ocellus, that are asymmetrically situated in the brain. The ciliary photoreceptor cells of these ocelli resemble visual cells of the vertebrate retina. Precise elucidation of the lineage of the photoreceptor cells will be key to understanding the developmental mechanisms of these cells as well as the evolutionary relationships between the photoreceptor organs of ascidians and vertebrates. Photoreceptor cells of the pigmented ocellus have been thought to develop from anterior animal (a-lineage) blastomeres, whereas the developmental origin of the nonpigmented ocellus has not been determined. Here, we show that the photoreceptor cells of both ocelli develop from the right anterior vegetal hemisphere: those of the pigmented ocellus from the right A9.14 cell and those of the nonpigmented ocellus from the right A9.16 cell. The pigmented ocellus is formed by a combination of two lineages of cells with distinct embryonic origins: the photoreceptor cells originate from a medial portion of the A-lineage neural plate, while the pigment cell originates from the lateral edge of the a-lineage neural plate. In light of the recently proposed close evolutionary relationship between the ocellus pigment cell of ascidians and the cephalic neural crest of vertebrates, the ascidian ocellus may represent a prototypic contribution of the neural crest to a cranial sensory organ.
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Affiliation(s)
- Kouhei Oonuma
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Moeko Tanaka
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Koki Nishitsuji
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Yumiko Kato
- Graduate School of Life Science, University of Hyogo, Kamigori, Hyogo, Japan
| | - Kotaro Shimai
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan
| | - Takehiro G Kusakabe
- Department of Biology, Faculty of Science and Engineering, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan; Institute for Integrative Neurobiology, Graduate School of Natural Science, Konan University, 8-9-1 Okamoto, Higashinada-ku, Kobe 658-8501, Japan.
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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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Bueno D, Garcia-Fernàndez J. Evolutionary development of embryonic cerebrospinal fluid composition and regulation: an open research field with implications for brain development and function. Fluids Barriers CNS 2016; 13:5. [PMID: 26979569 PMCID: PMC4793645 DOI: 10.1186/s12987-016-0029-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 03/10/2016] [Indexed: 12/29/2022] Open
Abstract
Within the consolidated field of evolutionary development, there is emerging research on evolutionary aspects of central nervous system development and its implications for adult brain structure and function, including behaviour. The central nervous system is one of the most intriguing systems in complex metazoans, as it controls all body and mind functions. Its failure is responsible for a number of severe and largely incurable diseases, including neurological and neurodegenerative ones. Moreover, the evolution of the nervous system is thought to be a critical step in the adaptive radiation of vertebrates. Brain formation is initiated early during development. Most embryological, genetic and evolutionary studies have focused on brain neurogenesis and regionalisation, including the formation and function of organising centres, and the comparison of homolog gene expression and function among model organisms from different taxa. The architecture of the vertebrate brain primordium also reveals the existence of connected internal cavities, the cephalic vesicles, which in fetuses and adults become the ventricular system of the brain. During embryonic and fetal development, brain cavities and ventricles are filled with a complex, protein-rich fluid called cerebrospinal fluid (CSF). However, CSF has not been widely analysed from either an embryological or evolutionary perspective. Recently, it has been demonstrated in higher vertebrates that embryonic cerebrospinal fluid has key functions in delivering diffusible signals and nutrients to the developing brain, thus contributing to the proliferation, differentiation and survival of neural progenitor cells, and to the expansion and patterning of the brain. Moreover, it has been shown that the composition and homeostasis of CSF are tightly controlled in a time-dependent manner from the closure of the anterior neuropore, just before the initiation of primary neurogenesis, up to the formation of functional choroid plexuses. In this review, we draw together existing literature about the formation, function and homeostatic regulation of embryonic cerebrospinal fluid, from the closure of the anterior neuropore to the formation of functional fetal choroid plexuses, from an evolutionary perspective. The relevance of these processes to the normal functions and diseases of adult brain will also be discussed.
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Affiliation(s)
- David Bueno
- Department of Genetics, Microbiology and Statistics, Unit of Biomedical, Evolutionary and Developmental Genetics, Faculty of Biological Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Catalonia, Spain.
| | - Jordi Garcia-Fernàndez
- Department of Genetics, Microbiology and Statistics, Unit of Biomedical, Evolutionary and Developmental Genetics, Faculty of Biological Sciences, University of Barcelona, Av. Diagonal 643, 08028, Barcelona, Catalonia, Spain
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Morales Diaz H, Mejares E, Newman-Smith E, Smith WC. ACAM, a novel member of the neural IgCAM family, mediates anterior neural tube closure in a primitive chordate. Dev Biol 2016; 409:288-296. [PMID: 26542009 DOI: 10.1016/j.ydbio.2015.10.032] [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: 09/18/2015] [Revised: 10/30/2015] [Accepted: 10/30/2015] [Indexed: 01/18/2023]
Abstract
The neural IgCAM family of cell adhesion molecules, which includes NCAM and related molecules, has evolved via gene duplication and alternative splicing to allow for a wide range of isoforms with distinct functions and homophilic binding properties. A search for neural IgCAMs in ascidians (Ciona intestinalis, Ciona savignyi, and Phallusia mammillata) has identified a novel set of truncated family members that, unlike the known members, lack fibronectin III domains and consist of only repeated Ig domains. Within the tunicates this form appears to be unique to the ascidians, and it was designated ACAM, for Ascidian Cell Adhesion Molecule. In C. intestinalis ACAM is expressed in the developing neural plate and neural tube, with strongest expression in the anterior sensory vesicle precursor. Unlike the two other conventional neural IgCAMs in C. intestinalis, which are expressed maternally and throughout the morula and blastula stages, ACAM expression initiates at the gastrula stage. Moreover, C. intestinalis ACAM is a target of the homeodomain transcription factor OTX, which plays an essential role in the development of the anterior central nervous system. Morpholino (MO) knockdown shows that ACAM is required for neural tube closure. In MO-injected embryos neural tube closure was normal caudally, but the anterior neuropore remained open. A similar phenotype was seen with overexpression of a secreted version of ACAM. The presence of ACAM in ascidians highlights the diversity of this gene family in morphogenesis and neurodevelopment.
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Affiliation(s)
- Heidi Morales Diaz
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, United States
| | - Emil Mejares
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, United States
| | - Erin Newman-Smith
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, United States
| | - William C Smith
- Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, United States.
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Stach T, Anselmi C. High-precision morphology: bifocal 4D-microscopy enables the comparison of detailed cell lineages of two chordate species separated for more than 525 million years. BMC Biol 2015; 13:113. [PMID: 26700477 PMCID: PMC4690324 DOI: 10.1186/s12915-015-0218-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 12/08/2015] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Understanding the evolution of divergent developmental trajectories requires detailed comparisons of embryologies at appropriate levels. Cell lineages, the accurate visualization of cleavage patterns, tissue fate restrictions, and morphogenetic movements that occur during the development of individual embryos are currently available for few disparate animal taxa, encumbering evolutionarily meaningful comparisons. Tunicates, considered to be close relatives of vertebrates, are marine invertebrates whose fossil record dates back to 525 million years ago. Life-history strategies across this subphylum are radically different, and include biphasic ascidians with free swimming larvae and a sessile adult stage, and the holoplanktonic larvaceans. Despite considerable progress, notably on the molecular level, the exact extent of evolutionary conservation and innovation during embryology remain obscure. RESULTS Here, using the innovative technique of bifocal 4D-microscopy, we demonstrate exactly which characteristics in the cell lineages of the ascidian Phallusia mammillata and the larvacean Oikopleura dioica were conserved and which were altered during evolution. Our accurate cell lineage trees in combination with detailed three-dimensional representations clearly identify conserved correspondence in relative cell position, cell identity, and fate restriction in several lines from all prospective larval tissues. At the same time, we precisely pinpoint differences observable at all levels of development. These differences comprise fate restrictions, tissue types, complex morphogenetic movement patterns, numerous cases of heterochronous acceleration in the larvacean embryo, and differences in bilateral symmetry. CONCLUSIONS Our results demonstrate in extraordinary detail the multitude of developmental levels amenable to evolutionary innovation, including subtle changes in the timing of fate restrictions as well as dramatic alterations in complex morphogenetic movements. We anticipate that the precise spatial and temporal cell lineage data will moreover serve as a high-precision guide to devise experimental investigations of other levels, such as molecular interactions between cells or changes in gene expression underlying the documented structural evolutionary changes. Finally, the quantitative amount of digital high-precision morphological data will enable and necessitate software-based similarity assessments as the basis of homology hypotheses.
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Affiliation(s)
- Thomas Stach
- Institut für Biologie, Kompetenzzentrum Elektronenmikroskopie, Humboldt-Universität zu Berlin, Philippstrasse 13, Haus 14, 10115, Berlin, Germany.
| | - Chiara Anselmi
- Dipartimento di Biologia, Università degli Studi di Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy.
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Multiobjective triclustering of time-series transcriptome data reveals key genes of biological processes. BMC Bioinformatics 2015; 16:200. [PMID: 26108437 PMCID: PMC4480927 DOI: 10.1186/s12859-015-0635-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 06/01/2015] [Indexed: 01/12/2023] Open
Abstract
Background Exploratory analysis of multi-dimensional high-throughput datasets, such as microarray gene expression time series, may be instrumental in understanding the genetic programs underlying numerous biological processes. In such datasets, variations in the gene expression profiles are usually observed across replicates and time points. Thus mining the temporal expression patterns in such multi-dimensional datasets may not only provide insights into the key biological processes governing organs to grow and develop but also facilitate the understanding of the underlying complex gene regulatory circuits. Results In this work we have developed an evolutionary multi-objective optimization for our previously introduced triclustering algorithm δ-TRIMAX. Its aim is to make optimal use of δ-TRIMAX in extracting groups of co-expressed genes from time series gene expression data, or from any 3D gene expression dataset, by adding the powerful capabilities of an evolutionary algorithm to retrieve overlapping triclusters. We have compared the performance of our newly developed algorithm, EMOA- δ-TRIMAX, with that of other existing triclustering approaches using four artificial dataset and three real-life datasets. Moreover, we have analyzed the results of our algorithm on one of these real-life datasets monitoring the differentiation of human induced pluripotent stem cells (hiPSC) into mature cardiomyocytes. For each group of co-expressed genes belonging to one tricluster, we identified key genes by computing their membership values within the tricluster. It turned out that to a very high percentage, these key genes were significantly enriched in Gene Ontology categories or KEGG pathways that fitted very well to the biological context of cardiomyocytes differentiation. Conclusions EMOA- δ-TRIMAX has proven instrumental in identifying groups of genes in transcriptomic data sets that represent the functional categories constituting the biological process under study. The executable file can be found at http://www.bioinf.med.uni-goettingen.de/fileadmin/download/EMOA-delta-TRIMAX.tar.gz. Electronic supplementary material The online version of this article (doi:10.1186/s12859-015-0635-8) contains supplementary material, which is available to authorized users.
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Hudson C, Sirour C, Yasuo H. Snail mediates medial-lateral patterning of the ascidian neural plate. Dev Biol 2015; 403:172-9. [PMID: 25962578 DOI: 10.1016/j.ydbio.2015.04.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/20/2015] [Accepted: 04/24/2015] [Indexed: 11/30/2022]
Abstract
The ascidian neural plate exhibits a regular, grid-like arrangement of cells. Patterning of the neural plate across the medial-lateral axis is initiated by bilateral sources of Nodal signalling, such that Nodal signalling induces expression of lateral neural plate genes and represses expression of medial neural plate genes. One of the earliest lateral neural plate genes induced by Nodal signals encodes the transcription factor Snail. Here, we show that Snail is a critical downstream factor mediating this Nodal-dependent patterning. Using gain and loss of function approaches, we show that Snail is required to repress medial neural plate gene expression at neural plate stages and to maintain the lateral neural tube genetic programme at later stages. A comparison of these results to those obtained following Nodal gain and loss of function indicates that Snail mediates a subset of Nodal functions. Consistently, overexpression of Snail can partially rescue a Nodal inhibition phenotype. We conclude that Snail is an early component of the gene regulatory network, initiated by Nodal signals, that patterns the ascidian neural plate.
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Affiliation(s)
- Clare Hudson
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France.
| | - Cathy Sirour
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
| | - Hitoyoshi Yasuo
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
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Diverse ETS transcription factors mediate FGF signaling in the Ciona anterior neural plate. Dev Biol 2015; 399:218-25. [PMID: 25576927 DOI: 10.1016/j.ydbio.2014.12.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/23/2014] [Accepted: 12/24/2014] [Indexed: 11/24/2022]
Abstract
The ascidian Ciona intestinalis is a marine invertebrate belonging to the sister group of the vertebrates, the tunicates. Its compact genome and simple, experimentally tractable embryos make Ciona well-suited for the study of cell-fate specification in chordates. Tunicate larvae possess a characteristic chordate body plan, and many developmental pathways are conserved between tunicates and vertebrates. Previous studies have shown that FGF signals are essential for neural induction and patterning at sequential steps of Ciona embryogenesis. Here we show that two different ETS family transcription factors, Ets1/2 and Elk1/3/4, have partially redundant activities in the anterior neural plate of gastrulating embryos. Whereas Ets1/2 promotes pigment cell formation in lateral lineages, both Ets1/2 and Elk1/3/4 are involved in the activation of Myt1L in medial lineages and the restriction of Six3/6 expression to the anterior-most regions of the neural tube. We also provide evidence that photoreceptor cells arise from posterior regions of the presumptive sensory vesicle, and do not depend on FGF signaling. Cells previously identified as photoreceptor progenitors instead form ependymal cells and neurons of the larval brain. Our results extend recent findings on FGF-dependent patterning of anterior-posterior compartments in the Ciona central nervous system.
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Veeman M, Reeves W. Quantitative and in toto imaging in ascidians: working toward an image-centric systems biology of chordate morphogenesis. Genesis 2015; 53:143-59. [PMID: 25262824 PMCID: PMC4378666 DOI: 10.1002/dvg.22828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 08/20/2014] [Accepted: 09/25/2014] [Indexed: 12/16/2022]
Abstract
Developmental biology relies heavily on microscopy to image the finely controlled cell behaviors that drive embryonic development. Most embryos are large enough that a field of view with the resolution and magnification needed to resolve single cells will not span more than a small region of the embryo. Ascidian embryos, however, are sufficiently small that they can be imaged in toto with fine subcellular detail using conventional microscopes and objectives. Unlike other model organisms with particularly small embryos, ascidians have a chordate embryonic body plan that includes a notochord, hollow dorsal neural tube, heart primordium and numerous other anatomical details conserved with the vertebrates. Here we compare the size and anatomy of ascidian embryos with those of more traditional model organisms, and relate these features to the capabilities of both conventional and exotic imaging methods. We review the emergence of Ciona and related ascidian species as model organisms for a new era of image-based developmental systems biology. We conclude by discussing some important challenges in ascidian imaging and image analysis that remain to be solved.
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Affiliation(s)
- Michael Veeman
- Division of Biology, Kansas State University, Manhattan KS, USA
| | - Wendy Reeves
- Division of Biology, Kansas State University, Manhattan KS, USA
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Esposito R, Racioppi C, Pezzotti MR, Branno M, Locascio A, Ristoratore F, Spagnuolo A. The ascidian pigmented sensory organs: structures and developmental programs. Genesis 2014; 53:15-33. [PMID: 25382437 DOI: 10.1002/dvg.22836] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 11/03/2014] [Accepted: 11/04/2014] [Indexed: 01/25/2023]
Abstract
The recent advances on ascidian pigment sensory organ development and function represent a fascinating platform to get insight on the basic programs of chordate eye formation. This review aims to summarize current knowledge, at the structural and molecular levels, on the two main building blocks of ascidian light sensory organ, i.e. pigment cells and photoreceptor cells. The unique features of these structures (e.g., simplicity and well characterized cell lineage) are indeed making it possible to dissect the developmental programs at single cell resolution and will soon provide a panel of molecular tools to be exploited for a deep developmental and comparative-evolutionary analysis.
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Affiliation(s)
- R Esposito
- Cellular and Developmental Biology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, NAPOLI, Italy
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Carlson M, Reeves W, Veeman M. Stochasticity and stereotypy in the Ciona notochord. Dev Biol 2014; 397:248-56. [PMID: 25459659 DOI: 10.1016/j.ydbio.2014.11.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 10/17/2014] [Accepted: 11/13/2014] [Indexed: 12/21/2022]
Abstract
Fate mapping with single cell resolution has typically been confined to embryos with completely stereotyped development. The lineages giving rise to the 40 cells of the Ciona notochord are invariant, but the intercalation of those cells into a single-file column is not. Here we use genetic labeling methods to fate map the Ciona notochord with both high resolution and large sample sizes. We find that the ordering of notochord cells into a single column is not random, but instead shows a distinctive signature characteristic of mediolaterally-biased intercalation. We find that patterns of cell intercalation in the notochord are somewhat stochastic but far more stereotyped than previously believed. Cell behaviors vary by lineage, with the secondary notochord lineage being much more constrained than the primary lineage. Within the primary lineage, patterns of intercalation reflect the geometry of the intercalating tissue. We identify the latest point at which notochord morphogenesis is largely stereotyped, which is shortly before the onset of mediolateral intercalation and immediately after the final cell divisions in the primary lineage. These divisions are consistently oriented along the AP axis. Our results indicate that the interplay between stereotyped and stochastic cell behaviors in morphogenesis can only be assessed by fate mapping experiments that have both cellular resolution and large sample sizes.
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Affiliation(s)
- Maia Carlson
- Division of Biology, Kansas State University, Manhattan, KS 66506, United States
| | - Wendy Reeves
- Division of Biology, Kansas State University, Manhattan, KS 66506, United States
| | - Michael Veeman
- Division of Biology, Kansas State University, Manhattan, KS 66506, United States.
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Fibroblast growth factor signalling controls nervous system patterning and pigment cell formation in Ciona intestinalis. Nat Commun 2014; 5:4830. [PMID: 25189217 DOI: 10.1038/ncomms5830] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 07/25/2014] [Indexed: 11/09/2022] Open
Abstract
During the development of the central nervous system (CNS), combinations of transcription factors and signalling molecules orchestrate patterning, specification and differentiation of neural cell types. In vertebrates, three types of melanin-containing pigment cells, exert a variety of functional roles including visual perception. Here we analysed the mechanisms underlying pigment cell specification within the CNS of a simple chordate, the ascidian Ciona intestinalis. Ciona tadpole larvae exhibit a basic chordate body plan characterized by a small number of neural cells. We employed lineage-specific transcription profiling to characterize the expression of genes downstream of fibroblast growth factor signalling, which govern pigment cell formation. We demonstrate that FGF signalling sequentially imposes a pigment cell identity at the expense of anterior neural fates. We identify FGF-dependent and pigment cell-specific factors, including the small GTPase, Rab32/38 and demonstrated its requirement for the pigmentation of larval sensory organs.
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Haupaix N, Abitua PB, Sirour C, Yasuo H, Levine M, Hudson C. Ephrin-mediated restriction of ERK1/2 activity delimits the number of pigment cells in the Ciona CNS. Dev Biol 2014; 394:170-80. [PMID: 25062608 DOI: 10.1016/j.ydbio.2014.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/04/2014] [Accepted: 07/10/2014] [Indexed: 12/31/2022]
Abstract
Recent evidence suggests that ascidian pigment cells are related to neural crest-derived melanocytes of vertebrates. Using live-imaging, we determine a revised cell lineage of the pigment cells in Ciona intestinalis embryos. The neural precursors undergo successive rounds of anterior-posterior (A-P) oriented cell divisions, starting at the blastula 64-cell stage. A previously unrecognized fourth A-P oriented cell division in the pigment cell lineage leads to the generation of the post-mitotic pigment cell precursors. We provide evidence that MEK/ERK signals are required for pigment cell specification until approximately 30min after the final cell division has taken place. Following each of the four A-P oriented cell divisions, ERK1/2 is differentially activated in the posterior sister cells, into which the pigment cell lineage segregates. Eph/ephrin signals are critical during the third A-P oriented cell division to spatially restrict ERK1/2 activation to the posterior daughter cell. Targeted inhibition of Eph/ephrin signals results in, at neurula stages, anterior expansion of both ERK1/2 activation and a pigment cell lineage marker and subsequently, at larval stages, supernumerary pigment cells. We discuss the implications of these findings with respect to the evolution of the vertebrate neural crest.
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Affiliation(s)
- Nicolas Haupaix
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Université de Nice Sophia Antipolis, Nice, France
| | - Philip B Abitua
- Center for Integrative Genomics, Division of Genetics, Genomics and Development, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Cathy Sirour
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
| | - Hitoyoshi Yasuo
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France
| | - 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
| | - Clare Hudson
- CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France; Sorbonne Universités, UPMC Univ Paris 06, Laboratoire de Biologie du Développement de Villefranche-sur-mer, Observatoire Océanologique, 06230 Villefranche-sur-mer, France.
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43
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Yamada A, Nishida H. Control of the number of cell division rounds in distinct tissues during ascidian embryogenesis. Dev Growth Differ 2014; 56:376-86. [DOI: 10.1111/dgd.12141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/30/2014] [Accepted: 04/07/2014] [Indexed: 01/13/2023]
Affiliation(s)
- Atsuko Yamada
- Department of Biological Sciences; Graduate School of Science; Osaka University; Toyonaka Osaka Japan
- International College; Osaka University; Toyonaka Osaka Japan
| | - Hiroki Nishida
- Department of Biological Sciences; Graduate School of Science; Osaka University; Toyonaka Osaka Japan
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44
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Russo MT, Racioppi C, Zanetti L, Ristoratore F. Expression of a single prominin homolog in the embryo of the model chordate Ciona intestinalis. Gene Expr Patterns 2014; 15:38-45. [PMID: 24755348 DOI: 10.1016/j.gep.2014.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 12/21/2022]
Abstract
Prominins are a family of pentaspan transmembrane glycoproteins, expressed in various types of cells, including stem and cancer stem cells in mammals. Prominin-1 is critical in generating and maintaining the structure of the photoreceptors in the eye since mutations in the PROM1 gene are associated with retinal and macular degeneration in human. In this study, we identified a single prominin homolog, Ci-prom1/2, in the model chordate the ascidian Ciona intestinalis and characterized Ci-prom1/2 expression profile in relation to photoreceptor differentiation during Ciona embryonic development. In situ hybridization experiments show Ci-prom1/2 transcripts localized in the developing central nervous system, predominantly in photoreceptor cell precursors as early as neurula stage and expression is maintained through larva stage in photoreceptor cells around the simple eye. We also isolated the regulatory region responsible for the specific spatio-temporal expression of the Ci-prom1/2 in photoreceptor cell lineage. Collectively, we report that Ci-prom1/2 is a novel molecular marker for ascidian photoreceptor cells and might represent a potential source to enlarge the knowledge about the function of prominin family in photoreceptor cell evolution and development.
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Affiliation(s)
- Monia T Russo
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Claudia Racioppi
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Laura Zanetti
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy
| | - Filomena Ristoratore
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dorhn, Villa Comunale, 80121 Napoli, Italy.
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45
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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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46
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Three-dimensional anatomy of the Ciona intestinalis tailbud embryo at single-cell resolution. Dev Biol 2012; 372:274-84. [DOI: 10.1016/j.ydbio.2012.09.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 08/10/2012] [Accepted: 09/13/2012] [Indexed: 11/17/2022]
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47
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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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48
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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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49
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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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50
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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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