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Miles KD, Barker CM, Russell KP, Appel BH, Doll CA. Electrical Synapses Mediate Embryonic Hyperactivity in a Zebrafish Model of Fragile X Syndrome. J Neurosci 2024; 44:e2275232024. [PMID: 38969506 PMCID: PMC11293453 DOI: 10.1523/jneurosci.2275-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 06/19/2024] [Accepted: 06/27/2024] [Indexed: 07/07/2024] Open
Abstract
Although hyperactivity is associated with a wide variety of neurodevelopmental disorders, the early embryonic origins of locomotion have hindered investigation of pathogenesis of these debilitating behaviors. The earliest motor output in vertebrate animals is generated by clusters of early-born motor neurons (MNs) that occupy distinct regions of the spinal cord, innervating stereotyped muscle groups. Gap junction electrical synapses drive early spontaneous behavior in zebrafish, prior to the emergence of chemical neurotransmitter networks. We use a genetic model of hyperactivity to gain critical insight into the consequences of errors in motor circuit formation and function, finding that Fragile X syndrome model mutant zebrafish are hyperexcitable from the earliest phases of spontaneous behavior, show altered sensitivity to blockade of electrical gap junctions, and have increased expression of the gap junction protein Connexin 34/35. We further show that this hyperexcitable behavior can be rescued by pharmacological inhibition of electrical synapses. We also use functional imaging to examine MN and interneuron (IN) activity in early embryogenesis, finding genetic disruption of electrical gap junctions uncouples activity between mnx1 + MNs and INs. Taken together, our work highlights the importance of electrical synapses in motor development and suggests that the origins of hyperactivity in neurodevelopmental disorders may be established during the initial formation of locomotive circuits.
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Affiliation(s)
- Kaleb D Miles
- Section of Developmental Biology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Chase M Barker
- Section of Developmental Biology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Kristen P Russell
- Section of Developmental Biology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Bruce H Appel
- Section of Developmental Biology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Caleb A Doll
- Section of Developmental Biology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado, Anschutz Medical Campus, Aurora, Colorado 80045
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Renaux E, Baudouin C, Marchese D, Clovis Y, Lee SK, Gofflot F, Rezsohazy R, Clotman F. Lhx4 surpasses its paralog Lhx3 in promoting the differentiation of spinal V2a interneurons. Cell Mol Life Sci 2024; 81:286. [PMID: 38970652 PMCID: PMC11335214 DOI: 10.1007/s00018-024-05316-x] [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: 04/03/2024] [Revised: 06/11/2024] [Accepted: 06/12/2024] [Indexed: 07/08/2024]
Abstract
Paralog factors are considered to ensure the robustness of biological processes by providing redundant activity in cells where they are co-expressed. However, the specific contribution of each factor is frequently underestimated. In the developing spinal cord, multiple families of transcription factors successively contribute to differentiate an initially homogenous population of neural progenitors into a myriad of neuronal subsets with distinct molecular, morphological, and functional characteristics. The LIM-homeodomain transcription factors Lhx3, Lhx4, Isl1 and Isl2 promote the segregation and differentiation of spinal motor neurons and V2 interneurons. Based on their high sequence identity and their similar distribution, the Lhx3 and Lhx4 paralogs are considered to contribute similarly to these processes. However, the specific contribution of Lhx4 has never been studied. Here, we provide evidence that Lhx3 and Lhx4 are present in the same cell populations during spinal cord development. Similarly to Lhx3, Lhx4 can form multiproteic complexes with Isl1 or Isl2 and the nuclear LIM interactor NLI. Lhx4 can stimulate a V2-specific enhancer more efficiently than Lhx3 and surpasses Lhx3 in promoting the differentiation of V2a interneurons in chicken embryo electroporation experiments. Finally, Lhx4 inactivation in mice results in alterations of differentiation of the V2a subpopulation, but not of motor neuron production, suggesting that Lhx4 plays unique roles in V2a differentiation that are not compensated by the presence of Lhx3. Thus, Lhx4 could be the major LIM-HD factor involved in V2a interneuron differentiation during spinal cord development and should be considered for in vitro differentiation of spinal neuronal populations.
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Affiliation(s)
- Estelle Renaux
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology, Animal Molecular and Cellular Biology, Louvain-la-Neuve, 1348, Belgium
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, 1200, Belgium
| | - Charlotte Baudouin
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, 1200, Belgium
| | - Damien Marchese
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology, Animal Molecular and Cellular Biology, Louvain-la-Neuve, 1348, Belgium
| | - Yoanne Clovis
- Pediatric Neuroscience Research Program, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Soo-Kyung Lee
- Pediatric Neuroscience Research Program, Papé Family Pediatric Research Institute, Department of Pediatrics, Oregon Health and Science University, Portland, OR, 97239, USA
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, 14260, USA
| | - Françoise Gofflot
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology, Animal Molecular and Cellular Biology, Louvain-la-Neuve, 1348, Belgium
| | - René Rezsohazy
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology, Animal Molecular and Cellular Biology, Louvain-la-Neuve, 1348, Belgium
| | - Frédéric Clotman
- Université catholique de Louvain, Louvain Institute of Biomolecular Science and Technology, Animal Molecular and Cellular Biology, Louvain-la-Neuve, 1348, Belgium.
- Université catholique de Louvain, Institute of Neuroscience, Laboratory of Neural Differentiation, Brussels, 1200, Belgium.
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3
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Iglesias Gonzalez AB, Koning HK, Tuz-Sasik MU, van Osselen I, Manuel R, Boije H. Perturbed development of calb2b expressing dI6 interneurons and motor neurons underlies locomotor defects observed in calretinin knock-down zebrafish larvae. Dev Biol 2024; 508:77-87. [PMID: 38278086 DOI: 10.1016/j.ydbio.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 12/15/2023] [Accepted: 01/02/2024] [Indexed: 01/28/2024]
Abstract
Calcium binding proteins are essential for neural development and cellular activity. Calretinin, encoded by calb2a and calb2b, plays a role during early zebrafish development and has been proposed as a marker for distinct neuronal populations within the locomotor network. We generated a calb2b:hs:eGFP transgenic reporter line to characterize calretinin expressing cells in the developing spinal cord and describe morphological and behavioral defects in calretinin knock-down larvae. eGFP was detected in primary and secondary motor neurons, as well as in dI6 and V0v interneurons. Knock-down of calretinin lead to disturbed development of motor neurons and dI6 interneurons, revealing a crucial role during early development of the locomotor network. Primary motor neurons showed delayed axon outgrowth and the distinct inhibitory CoLo neurons, originating from the dI6 lineage, were absent. These observations explain the locomotor defects we observed in calretinin knock-down animals where the velocity, acceleration and coordination were affected during escapes. Altogether, our analysis suggests an essential role for calretinin during the development of the circuits regulating escape responses and fast movements within the locomotor network.
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Affiliation(s)
| | - Harmen Kornelis Koning
- Department of Immunology, Genetics and Pathology, Uppsala University, S-75108, Uppsala, Sweden
| | - Melek Umay Tuz-Sasik
- Department of Immunology, Genetics and Pathology, Uppsala University, S-75108, Uppsala, Sweden
| | - Ilse van Osselen
- Department of Immunology, Genetics and Pathology, Uppsala University, S-75108, Uppsala, Sweden
| | - Remy Manuel
- Department of Immunology, Genetics and Pathology, Uppsala University, S-75108, Uppsala, Sweden
| | - Henrik Boije
- Department of Immunology, Genetics and Pathology, Uppsala University, S-75108, Uppsala, Sweden.
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Asakawa K, Handa H, Kawakami K. In Vivo Optogenetic Phase Transition of an Intrinsically Disordered Protein. Methods Mol Biol 2024; 2707:257-264. [PMID: 37668918 DOI: 10.1007/978-1-0716-3401-1_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Proteins containing intrinsically disordered regions (IDRs) control a wide variety of cellular processes by assembly of membrane-less organelles via IDR-mediated liquid-liquid phase separation. Dysregulated IDR-mediated phase transition has been implicated in the pathogenesis of diseases characterized by deposition of abnormal protein aggregates. Here, we describe a method to enhance interactions between the IDRs of the RNA/DNA-binding protein and TAR DNA-binding protein 43 (TDP-43) by light to drive its phase transition in the motor neurons of zebrafish. The optically controlled TDP-43 phase transition in motor neurons, in vivo, provides a unique opportunity to evaluate the impact of dysregulated TDP-43 phase transition on the physiology of motor neurons. This will help to address the etiology of neurodegenerative diseases associated with abnormal TDP-43 phase transition and aggregation, including amyotrophic lateral sclerosis (ALS).
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Affiliation(s)
- Kazuhide Asakawa
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan.
| | - Hiroshi Handa
- Department of Molecular Pharmacology, Center for Future Medical Research, Tokyo Medical University, Tokyo, Japan
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
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Lin SJ, Vona B, Lau T, Huang K, Zaki MS, Aldeen HS, Karimiani EG, Rocca C, Noureldeen MM, Saad AK, Petree C, Bartolomaeus T, Abou Jamra R, Zifarelli G, Gotkhindikar A, Wentzensen IM, Liao M, Cork EE, Varshney P, Hashemi N, Mohammadi MH, Rad A, Neira J, Toosi MB, Knopp C, Kurth I, Challman TD, Smith R, Abdalla A, Haaf T, Suri M, Joshi M, Chung WK, Moreno-De-Luca A, Houlden H, Maroofian R, Varshney GK. Evaluating the association of biallelic OGDHL variants with significant phenotypic heterogeneity. Genome Med 2023; 15:102. [PMID: 38031187 PMCID: PMC10688095 DOI: 10.1186/s13073-023-01258-4] [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: 09/19/2023] [Accepted: 11/13/2023] [Indexed: 12/01/2023] Open
Abstract
BACKGROUND Biallelic variants in OGDHL, encoding part of the α-ketoglutarate dehydrogenase complex, have been associated with highly heterogeneous neurological and neurodevelopmental disorders. However, the validity of this association remains to be confirmed. A second OGDHL patient cohort was recruited to carefully assess the gene-disease relationship. METHODS Using an unbiased genotype-first approach, we screened large, multiethnic aggregated sequencing datasets worldwide for biallelic OGDHL variants. We used CRISPR/Cas9 to generate zebrafish knockouts of ogdhl, ogdh paralogs, and dhtkd1 to investigate functional relationships and impact during development. Functional complementation with patient variant transcripts was conducted to systematically assess protein functionality as a readout for pathogenicity. RESULTS A cohort of 14 individuals from 12 unrelated families exhibited highly variable clinical phenotypes, with the majority of them presenting at least one additional variant, potentially accounting for a blended phenotype and complicating phenotypic understanding. We also uncovered extreme clinical heterogeneity and high allele frequencies, occasionally incompatible with a fully penetrant recessive disorder. Human cDNA of previously described and new variants were tested in an ogdhl zebrafish knockout model, adding functional evidence for variant reclassification. We disclosed evidence of hypomorphic alleles as well as a loss-of-function variant without deleterious effects in zebrafish variant testing also showing discordant familial segregation, challenging the relationship of OGDHL as a conventional Mendelian gene. Going further, we uncovered evidence for a complex compensatory relationship among OGDH, OGDHL, and DHTKD1 isoenzymes that are associated with neurodevelopmental disorders and exhibit complex transcriptional compensation patterns with partial functional redundancy. CONCLUSIONS Based on the results of genetic, clinical, and functional studies, we formed three hypotheses in which to frame observations: biallelic OGDHL variants lead to a highly variable monogenic disorder, variants in OGDHL are following a complex pattern of inheritance, or they may not be causative at all. Our study further highlights the continuing challenges of assessing the validity of reported disease-gene associations and effects of variants identified in these genes. This is particularly more complicated in making genetic diagnoses based on identification of variants in genes presenting a highly heterogenous phenotype such as "OGDHL-related disorders".
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Affiliation(s)
- Sheng-Jia Lin
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Barbara Vona
- Institute of Human Genetics, Julius Maximilians University Würzburg, Würzburg, Germany
- Institute of Human Genetics, University Medical Center Göttingen, Göttingen, Germany
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Department of Otolaryngology-Head and Neck Surgery, Tübingen Hearing Research Center, Eberhard Karls University, Tübingen, 72076, Germany
| | - Tracy Lau
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Kevin Huang
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Huda Shujaa Aldeen
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Ehsan Ghayoor Karimiani
- Molecular and Clinical Sciences Institute, St. George's, University of London, Cranmer Terrace London, London, UK
| | - Clarissa Rocca
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Mahmoud M Noureldeen
- Department of Pediatrics, Faculty of Medicine, Beni-Suef University, Beni-Suef, Egypt
| | - Ahmed K Saad
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Cassidy Petree
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Tobias Bartolomaeus
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Rami Abou Jamra
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | | | | | | | | | - Emalyn Elise Cork
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Pratishtha Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA
| | - Narges Hashemi
- Department of Pediatrics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | | | - Aboulfazl Rad
- Department of Otolaryngology-Head and Neck Surgery, Tübingen Hearing Research Center, Eberhard Karls University, Tübingen, 72076, Germany
| | - Juanita Neira
- Department of Human Genetics, Emory University, Atlanta, GA, 30322, USA
| | - Mehran Beiraghi Toosi
- Department of Pediatrics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Cordula Knopp
- Institute for Human Genetics and Genomic Medicine, RWTH Aachen University, Pauwelsstr. 30, Aachen, 52074, Germany
| | - Ingo Kurth
- Institute for Human Genetics and Genomic Medicine, RWTH Aachen University, Pauwelsstr. 30, Aachen, 52074, Germany
| | - Thomas D Challman
- Autism & Developmental Medicine Institute, Geisinger, Lewisburg, PA, USA
| | - Rebecca Smith
- Autism & Developmental Medicine Institute, Geisinger, Lewisburg, PA, USA
| | - Asmahan Abdalla
- Department of Pediatric Endocrinology, Gaafar Ibn Auf Children's Tertiary Hospital, Khartoum, Sudan
| | - Thomas Haaf
- Institute of Human Genetics, Julius Maximilians University Würzburg, Würzburg, Germany
| | - Mohnish Suri
- Nottingham Clinical Genetics Service, Nottingham University Hospitals NHS Trust, Nottingham, UK
| | - Manali Joshi
- Bioinformatics Centre, S. P. Pune University, Pune, India
| | - Wendy K Chung
- Department of Pediatrics, Boston Children's Hospitaland, Harvard Medical School , Boston, MA, USA
| | - Andres Moreno-De-Luca
- Department of Diagnostic Radiology, Kingston Health Sciences Centre, Queen's University, Kingston, ON, Canada
| | - Henry Houlden
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK.
| | - Gaurav K Varshney
- Genes & Human Disease Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA.
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Kelly JJ, Wen H, Brehm P. Single-cell RNAseq analysis of spinal locomotor circuitry in larval zebrafish. eLife 2023; 12:RP89338. [PMID: 37975797 PMCID: PMC10656102 DOI: 10.7554/elife.89338] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023] Open
Abstract
Identification of the neuronal types that form the specialized circuits controlling distinct behaviors has benefited greatly from the simplicity offered by zebrafish. Electrophysiological studies have shown that in addition to connectivity, understanding of circuitry requires identification of functional specializations among individual circuit components, such as those that regulate levels of transmitter release and neuronal excitability. In this study, we use single-cell RNA sequencing (scRNAseq) to identify the molecular bases for functional distinctions between motoneuron types that are causal to their differential roles in swimming. The primary motoneuron, in particular, expresses high levels of a unique combination of voltage-dependent ion channel types and synaptic proteins termed functional 'cassettes.' The ion channel types are specialized for promoting high-frequency firing of action potentials and augmented transmitter release at the neuromuscular junction, both contributing to greater power generation. Our transcriptional profiling of spinal neurons further assigns expression of this cassette to specific interneuron types also involved in the central circuitry controlling high-speed swimming and escape behaviors. Our analysis highlights the utility of scRNAseq in functional characterization of neuronal circuitry, in addition to providing a gene expression resource for studying cell type diversity.
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Affiliation(s)
- Jimmy J Kelly
- Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
| | - Hua Wen
- Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
| | - Paul Brehm
- Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
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7
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Toni M, Arena C, Cioni C, Tedeschi G. Temperature- and chemical-induced neurotoxicity in zebrafish. Front Physiol 2023; 14:1276941. [PMID: 37854466 PMCID: PMC10579595 DOI: 10.3389/fphys.2023.1276941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 09/22/2023] [Indexed: 10/20/2023] Open
Abstract
Throughout their lives, humans encounter a plethora of substances capable of inducing neurotoxic effects, including drugs, heavy metals and pesticides. Neurotoxicity manifests when exposure to these chemicals disrupts the normal functioning of the nervous system, and some neurotoxic agents have been linked to neurodegenerative pathologies such as Parkinson's and Alzheimer's disease. The growing concern surrounding the neurotoxic impacts of both naturally occurring and man-made toxic substances necessitates the identification of animal models for rapid testing across a wide spectrum of substances and concentrations, and the utilization of tools capable of detecting nervous system alterations spanning from the molecular level up to the behavioural one. Zebrafish (Danio rerio) is gaining prominence in the field of neuroscience due to its versatility. The possibility of analysing all developmental stages (embryo, larva and adult), applying the most common "omics" approaches (transcriptomics, proteomics, lipidomics, etc.) and conducting a wide range of behavioural tests makes zebrafish an excellent model for neurotoxicity studies. This review delves into the main experimental approaches adopted and the main markers analysed in neurotoxicity studies in zebrafish, showing that neurotoxic phenomena can be triggered not only by exposure to chemical substances but also by fluctuations in temperature. The findings presented here serve as a valuable resource for the study of neurotoxicity in zebrafish and define new scenarios in ecotoxicology suggesting that alterations in temperature can synergistically compound the neurotoxic effects of chemical substances, intensifying their detrimental impact on fish populations.
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Affiliation(s)
- Mattia Toni
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Chiara Arena
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Carla Cioni
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Rome, Italy
| | - Gabriella Tedeschi
- Department of Veterinary Medicine and Animal Science (DIVAS), Università Degli Studi di Milano, Milano, Italy
- CRC “Innovation for Well-Being and Environment” (I-WE), Università Degli Studi di Milano, Milano, Italy
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D'Elia KP, Hameedy H, Goldblatt D, Frazel P, Kriese M, Zhu Y, Hamling KR, Kawakami K, Liddelow SA, Schoppik D, Dasen JS. Determinants of motor neuron functional subtypes important for locomotor speed. Cell Rep 2023; 42:113049. [PMID: 37676768 PMCID: PMC10600875 DOI: 10.1016/j.celrep.2023.113049] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/12/2023] [Accepted: 08/11/2023] [Indexed: 09/09/2023] Open
Abstract
Locomotion requires precise control of the strength and speed of muscle contraction and is achieved by recruiting functionally distinct subtypes of motor neurons (MNs). MNs are essential to movement and differentially susceptible in disease, but little is known about how MNs acquire functional subtype-specific features during development. Using single-cell RNA profiling in embryonic and larval zebrafish, we identify novel and conserved molecular signatures for MN functional subtypes and identify genes expressed in both early post-mitotic and mature MNs. Assessing MN development in genetic mutants, we define a molecular program essential for MN functional subtype specification. Two evolutionarily conserved transcription factors, Prdm16 and Mecom, are both functional subtype-specific determinants integral for fast MN development. Loss of prdm16 or mecom causes fast MNs to develop transcriptional profiles and innervation similar to slow MNs. These results reveal the molecular diversity of vertebrate axial MNs and demonstrate that functional subtypes are specified through intrinsic transcriptional codes.
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Affiliation(s)
- Kristen P D'Elia
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Hanna Hameedy
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Dena Goldblatt
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA; Center for Neural Science, New York University, New York, NY, USA
| | - Paul Frazel
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - Mercer Kriese
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Yunlu Zhu
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kyla R Hamling
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Japan
| | - Shane A Liddelow
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA
| | - David Schoppik
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA; Department of Otolaryngology, New York University Grossman School of Medicine, New York, NY, USA.
| | - Jeremy S Dasen
- Department of Neuroscience & Physiology and Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, USA.
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9
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Kelly JJ, Wen H, Brehm P. Single cell RNA-seq analysis of spinal locomotor circuitry in larval zebrafish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543939. [PMID: 37333232 PMCID: PMC10274715 DOI: 10.1101/2023.06.06.543939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Identification of the neuronal types that form the specialized circuits controlling distinct behaviors has benefited greatly from the simplicity offered by zebrafish. Electrophysiological studies have shown that additional to connectivity, understanding of circuitry requires identification of functional specializations among individual circuit components, such as those that regulate levels of transmitter release and neuronal excitability. In this study we use single cell RNA sequencing (scRNAseq) to identify the molecular bases for functional distinctions between motoneuron types that are causal to their differential roles in swimming. The primary motoneuron (PMn) in particular, expresses high levels of a unique combination of voltage-dependent ion channel types and synaptic proteins termed functional 'cassettes'. The ion channel types are specialized for promoting high frequency firing of action potentials and augmented transmitter release at the neuromuscular junction, both contributing to greater power generation. Our transcriptional profiling of spinal neurons further assigns expression of this cassette to specific interneuron types also involved in the central circuitry controlling high speed swimming and escape behaviors. Our analysis highlights the utility of scRNAseq in functional characterization of neuronal circuitry, in addition to providing a gene expression resource for studying cell type diversity.
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Affiliation(s)
- Jimmy J Kelly
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Hua Wen
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA
| | - Paul Brehm
- Vollum Institute, Oregon Health & Science University, Portland, OR, USA
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10
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Wilson AC, Sweeney LB. Spinal cords: Symphonies of interneurons across species. Front Neural Circuits 2023; 17:1146449. [PMID: 37180760 PMCID: PMC10169611 DOI: 10.3389/fncir.2023.1146449] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/23/2023] [Indexed: 05/16/2023] Open
Abstract
Vertebrate movement is orchestrated by spinal inter- and motor neurons that, together with sensory and cognitive input, produce dynamic motor behaviors. These behaviors vary from the simple undulatory swimming of fish and larval aquatic species to the highly coordinated running, reaching and grasping of mice, humans and other mammals. This variation raises the fundamental question of how spinal circuits have changed in register with motor behavior. In simple, undulatory fish, exemplified by the lamprey, two broad classes of interneurons shape motor neuron output: ipsilateral-projecting excitatory neurons, and commissural-projecting inhibitory neurons. An additional class of ipsilateral inhibitory neurons is required to generate escape swim behavior in larval zebrafish and tadpoles. In limbed vertebrates, a more complex spinal neuron composition is observed. In this review, we provide evidence that movement elaboration correlates with an increase and specialization of these three basic interneuron types into molecularly, anatomically, and functionally distinct subpopulations. We summarize recent work linking neuron types to movement-pattern generation across fish, amphibians, reptiles, birds and mammals.
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Affiliation(s)
| | - Lora B. Sweeney
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Lower Austria, Austria
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11
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Single-cell transcriptomic analysis reveals diversity within mammalian spinal motor neurons. Nat Commun 2023; 14:46. [PMID: 36596814 PMCID: PMC9810664 DOI: 10.1038/s41467-022-35574-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 12/12/2022] [Indexed: 01/05/2023] Open
Abstract
Spinal motor neurons (MNs) integrate sensory stimuli and brain commands to generate movements. In vertebrates, the molecular identities of the cardinal MN types such as those innervating limb versus trunk muscles are well elucidated. Yet the identities of finer subtypes within these cell populations that innervate individual muscle groups remain enigmatic. Here we investigate heterogeneity in mouse MNs using single-cell transcriptomics. Among limb-innervating MNs, we reveal a diverse neuropeptide code for delineating putative motor pool identities. Additionally, we uncover that axial MNs are subdivided into three molecularly distinct subtypes, defined by mediolaterally-biased Satb2, Nr2f2 or Bcl11b expression patterns with different axon guidance signatures. These three subtypes are present in chicken and human embryos, suggesting a conserved axial MN expression pattern across higher vertebrates. Overall, our study provides a molecular resource of spinal MN types and paves the way towards deciphering how neuronal subtypes evolved to accommodate vertebrate motor behaviors.
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12
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Singh BJ, Zu L, Summers J, Asdjodi S, Glasgow E, Kanwal JS. NemoTrainer: Automated Conditioning for Stimulus-Directed Navigation and Decision Making in Free-Swimming Zebrafish. Animals (Basel) 2022; 13:ani13010116. [PMID: 36611725 PMCID: PMC9817937 DOI: 10.3390/ani13010116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
Current methods for associative conditioning in animals involve human intervention that is labor intensive, stressful to animals, and introduces experimenter bias in the data. Here, we describe a simple apparatus and a flexible, microcontroller-based conditioning paradigm that minimizes human intervention. Our methodology exploits directed movement towards a target that depends on spatial working memory, including processing of sensory inputs, motivational drive, and attentional mechanisms. Within a stimulus-driven conditioning paradigm designed to train zebrafish, we present a localized pulse of light via LEDs and/or sounds via an underwater transducer. A webcam placed below a glass tank records fish-swimming behavior. For classical conditioning, animals simply associate a sound or light with an unconditioned stimulus, such as a small food reward presented at a fixed location, and swim towards that location to obtain a few grains of food dispensed automatically via a sensor-triggered, stepper motor. During operant conditioning, a fish must first approach a proximity sensor at a remote location and then swim to the reward location. For both types of conditioning, a timing-gated interrupt activates stepper motors via custom software embedded within a microcontroller (Arduino). "Ardulink", a Java facility, implements Arduino-computer communication protocols. In this way, a Java-based user interface running on a host computer can provide full experimental control. Alternatively, a similar level of control is achieved via an Arduino script communicating with an event-driven application controller running on the host computer. Either approach can enable precise, multi-day scheduling of training, including timing, location, and intensity of stimulus parameters; and the feeder. Learning can be tracked by monitoring turning, location, response times, and directional swimming of individual fish. This facilitates the comparison of performance within and across a cohort of animals. Our scheduling and control software and apparatus ("NemoTrainer") can be used to study multiple aspects of species-specific behaviors as well as the effects on them of various interventions.
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Affiliation(s)
- Bishen J. Singh
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
| | - Luciano Zu
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
| | - Jacqueline Summers
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
| | - Saman Asdjodi
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
| | - Eric Glasgow
- Department of Oncology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
| | - Jagmeet S. Kanwal
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20057-1460, USA
- Correspondence: ; Tel.: +1-(202)-687-1305
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13
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Barker CM, Miles KD, Doll CA. Fmrp regulates neuronal balance in embryonic motor circuit formation. Front Neurosci 2022; 16:962901. [PMID: 36408418 PMCID: PMC9669763 DOI: 10.3389/fnins.2022.962901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022] Open
Abstract
Motor behavior requires the balanced production and integration of a variety of neural cell types. Motor neurons are positioned in discrete locations in the spinal cord, targeting specific muscles to drive locomotive contractions. Specialized spinal interneurons modulate and synchronize motor neuron activity to achieve coordinated motor output. Changes in the ratios and connectivity of spinal interneurons could drastically alter motor output by tipping the balance of inhibition and excitation onto target motor neurons. Importantly, individuals with Fragile X syndrome (FXS) and associated autism spectrum disorders often have significant motor challenges, including repetitive behaviors and epilepsy. FXS stems from the transcriptional silencing of the gene Fragile X Messenger Ribonucleoprotein 1 (FMR1), which encodes an RNA binding protein that is implicated in a multitude of crucial neurodevelopmental processes, including cell specification. Our work shows that Fmrp regulates the formation of specific interneurons and motor neurons that comprise early embryonic motor circuits. We find that zebrafish fmr1 mutants generate surplus ventral lateral descending (VeLD) interneurons, an early-born cell derived from the motor neuron progenitor domain (pMN). As VeLD interneurons are hypothesized to act as central pattern generators driving the earliest spontaneous movements, this imbalance could influence the formation and long-term function of motor circuits driving locomotion. fmr1 embryos also show reduced expression of proteins associated with inhibitory synapses, including the presynaptic transporter vGAT and the postsynaptic scaffold Gephyrin. Taken together, we show changes in embryonic motor circuit formation in fmr1 mutants that could underlie persistent hyperexcitability.
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Affiliation(s)
- Chase M. Barker
- Section of Developmental Biology, Department of Pediatrics, Children’s Hospital Colorado, University of Colorado School of Medicine, Aurora, CO, United States
| | - Kaleb D. Miles
- Section of Developmental Biology, Department of Pediatrics, Children’s Hospital Colorado, University of Colorado School of Medicine, Aurora, CO, United States
- Biomedical Sciences and Biotechnology Program, Graduate School, University of Colorado, Aurora, CO, United States
| | - Caleb A. Doll
- Section of Developmental Biology, Department of Pediatrics, Children’s Hospital Colorado, University of Colorado School of Medicine, Aurora, CO, United States
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14
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Wong HTC, Drerup CM. Using fluorescent indicators for in vivo quantification of spontaneous or evoked motor neuron presynaptic activity in transgenic zebrafish. STAR Protoc 2022; 3:101766. [PMID: 36240058 PMCID: PMC9568885 DOI: 10.1016/j.xpro.2022.101766] [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: 07/01/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 11/07/2022] Open
Abstract
In this protocol, we describe steps that utilize the optical clarity of the zebrafish larvae and the stereotyped motor neuron axon structure in the trunk to measure spontaneous or evoked motor neuron axon activity. This activity is detected with transgenic fluorescent indicators introduced into the larvae by zygotic injection. Fluorescent indicator intensity changes in the small neuromuscular junctions are quantified to measure the presynaptic calcium activity and consequent synaptic vesicle release. For complete details on the use and execution of this protocol, please refer to Mandal et al. (2020).
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Affiliation(s)
- Hiu-tung Candy Wong
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA,Corresponding author
| | - Catherine M. Drerup
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA,Corresponding author
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15
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Huang CX, Wang Z, Cheng J, Zhu Z, Guan NN, Song J. De novo establishment of circuit modules restores locomotion after spinal cord injury in adult zebrafish. Cell Rep 2022; 41:111535. [DOI: 10.1016/j.celrep.2022.111535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/12/2022] [Accepted: 09/29/2022] [Indexed: 11/03/2022] Open
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16
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Alper SR, Dorsky RI. Unique advantages of zebrafish larvae as a model for spinal cord regeneration. Front Mol Neurosci 2022; 15:983336. [PMID: 36157068 PMCID: PMC9489991 DOI: 10.3389/fnmol.2022.983336] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 08/18/2022] [Indexed: 11/30/2022] Open
Abstract
The regenerative capacity of the spinal cord in mammals ends at birth. In contrast, teleost fish and amphibians retain this capacity throughout life, leading to the use of the powerful zebrafish model system to identify novel mechanisms that promote spinal cord regeneration. While adult zebrafish offer an effective comparison with non-regenerating mammals, they lack the complete array of experimental approaches that have made this animal model so successful. In contrast, the optical transparency, simple anatomy and complex behavior of zebrafish larvae, combined with the known conservation of pro-regenerative signals and cell types between larval and adult stages, suggest that they may hold even more promise as a system for investigating spinal cord regeneration. In this review, we highlight characteristics and advantages of the larval model that underlie its potential to provide future therapeutic approaches for treating human spinal cord injury.
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17
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Xing L, Chai R, Wang J, Lin J, Li H, Wang Y, Lai B, Sun J, Chen G. Expression of myelin transcription factor 1 and lamin B receptor mediate neural progenitor fate transition in the zebrafish spinal cord pMN domain. J Biol Chem 2022; 298:102452. [PMID: 36063998 PMCID: PMC9530849 DOI: 10.1016/j.jbc.2022.102452] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/17/2022] [Accepted: 08/20/2022] [Indexed: 02/05/2023] Open
Abstract
The pMN domain is a restricted domain in the ventral spinal cord, defined by the expression of the olig2 gene. Though it is known that the pMN progenitor cells can sequentially generate motor neurons and oligodendrocytes, the lineages of these progenitors are controversial and how their progeny are generated is not well understood. Using single-cell RNA sequencing, here, we identified a previously unknown heterogeneity among pMN progenitors with distinct fates and molecular signatures in zebrafish. Notably, we characterized two distinct motor neuron lineages using bioinformatic analysis. We then went on to investigate specific molecular programs that regulate neural progenitor fate transition. We validated experimentally that expression of the transcription factor myt1 (myelin transcription factor 1) and inner nuclear membrane integral proteins lbr (lamin B receptor) were critical for the development of motor neurons and neural progenitor maintenance, respectively. We anticipate that the transcriptome features and molecular programs identified in zebrafish pMN progenitors will not only provide an in-depth understanding of previous findings regarding the lineage analysis of oligodendrocyte progenitor cells and motor neurons but will also help in further understanding of the molecular programming involved in neural progenitor fate transition.
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Affiliation(s)
- Lingyan Xing
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China,For correspondence: Lingyan Xing; Gang Chen
| | - Rui Chai
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Jiaqi Wang
- Department of Physiology, School of Medicine, Nantong University, Nantong, China
| | - Jiaqi Lin
- Department of Physiology, School of Medicine, Nantong University, Nantong, China
| | - Hanyang Li
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Yueqi Wang
- School of Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Biqin Lai
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Junjie Sun
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Gang Chen
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China,Basic Medical Research Center, School of Medicine, Nantong University, Nantong, China,For correspondence: Lingyan Xing; Gang Chen
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18
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Habicher J, Manuel R, Pedroni A, Ferebee C, Ampatzis K, Boije H. A new transgenic reporter line reveals expression of protocadherin 9 at a cellular level within the zebrafish central nervous system. Gene Expr Patterns 2022; 44:119246. [DOI: 10.1016/j.gep.2022.119246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/07/2022] [Accepted: 04/09/2022] [Indexed: 11/16/2022]
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19
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Koning HK, Ahemaiti A, Boije H. A deep-dive into fictive locomotion - a strategy to probe cellular activity during speed transitions in fictively swimming zebrafish larvae. Biol Open 2022; 11:274799. [PMID: 35188534 PMCID: PMC8966775 DOI: 10.1242/bio.059167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/14/2022] [Indexed: 11/20/2022] Open
Abstract
Fictive locomotion is frequently used to study locomotor output in paralyzed animals. We have evaluated the character of swim episodes elicited by different strategies in zebrafish. Motor output was measured on both sides of a body segment using electrodes and a pipeline for synchronizing stimulation and recording, denoising data and peak-finding was developed. The optomotor response generated swims most equivalent to spontaneous activity, while electrical stimulation and NMDA application caused various artefacts. Our optimal settings, optomotor stimulation using 5-day-old larvae, were combined with calcium imaging and optogenetics to validate the setup's utility. Expression of GCaMP5G by the mnx1 promoter allowed correlation of calcium traces of dozens of motor neurons to the fictive locomotor output. Activation of motor neurons through channelrhodopsin produced aberrant locomotor episodes. This strategy can be used to investigate novel neuronal populations in a high-throughput manner to reveal their role in shaping motor output. This article has an associated First Person interview with the first author of the paper. Summary: This approach combines fictive locomotion, elicited through the optomotor response, and calcium imaging or optogenetics, to investigate the role of neuronal populations in shaping motor output.
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Affiliation(s)
- Harmen Kornelis Koning
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Aikeremu Ahemaiti
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
| | - Henrik Boije
- Department of Immunology, Genetics and Pathology, Uppsala University, S-751 08, Uppsala, Sweden
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20
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Dasen JS. Establishing the Molecular and Functional Diversity of Spinal Motoneurons. ADVANCES IN NEUROBIOLOGY 2022; 28:3-44. [PMID: 36066819 DOI: 10.1007/978-3-031-07167-6_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Spinal motoneurons are a remarkably diverse class of neurons responsible for facilitating a broad range of motor behaviors and autonomic functions. Studies of motoneuron differentiation have provided fundamental insights into the developmental mechanisms of neuronal diversification, and have illuminated principles of neural fate specification that operate throughout the central nervous system. Because of their relative anatomical simplicity and accessibility, motoneurons have provided a tractable model system to address multiple facets of neural development, including early patterning, neuronal migration, axon guidance, and synaptic specificity. Beyond their roles in providing direct communication between central circuits and muscle, recent studies have revealed that motoneuron subtype-specific programs also play important roles in determining the central connectivity and function of motor circuits. Cross-species comparative analyses have provided novel insights into how evolutionary changes in subtype specification programs may have contributed to adaptive changes in locomotor behaviors. This chapter focusses on the gene regulatory networks governing spinal motoneuron specification, and how studies of spinal motoneurons have informed our understanding of the basic mechanisms of neuronal specification and spinal circuit assembly.
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Affiliation(s)
- Jeremy S Dasen
- NYU Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY, USA.
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21
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Cavone L, McCann T, Drake LK, Aguzzi EA, Oprişoreanu AM, Pedersen E, Sandi S, Selvarajah J, Tsarouchas TM, Wehner D, Keatinge M, Mysiak KS, Henderson BEP, Dobie R, Henderson NC, Becker T, Becker CG. A unique macrophage subpopulation signals directly to progenitor cells to promote regenerative neurogenesis in the zebrafish spinal cord. Dev Cell 2021; 56:1617-1630.e6. [PMID: 34033756 DOI: 10.1016/j.devcel.2021.04.031] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 03/15/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022]
Abstract
Central nervous system injury re-initiates neurogenesis in anamniotes (amphibians and fishes), but not in mammals. Activation of the innate immune system promotes regenerative neurogenesis, but it is fundamentally unknown whether this is indirect through the activation of known developmental signaling pathways or whether immune cells directly signal to progenitor cells using mechanisms that are unique to regeneration. Using single-cell RNA-seq of progenitor cells and macrophages, as well as cell-type-specific manipulations, we provide evidence for a direct signaling axis from specific lesion-activated macrophages to spinal progenitor cells to promote regenerative neurogenesis in zebrafish. Mechanistically, TNFa from pro-regenerative macrophages induces Tnfrsf1a-mediated AP-1 activity in progenitors to increase regeneration-promoting expression of hdac1 and neurogenesis. This establishes the principle that macrophages directly communicate to spinal progenitor cells via non-developmental signals after injury, providing potential targets for future interventions in the regeneration-deficient spinal cord of mammals.
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Affiliation(s)
- Leonardo Cavone
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Tess McCann
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Louisa K Drake
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Erika A Aguzzi
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Ana-Maria Oprişoreanu
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Elisa Pedersen
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Soe Sandi
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Jathurshan Selvarajah
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Themistoklis M Tsarouchas
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Daniel Wehner
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK; Max Planck Institute for the Science of Light, Staudtstraße 2, Erlangen 91058, Germany; Max-Planck-Zentrum für Physik und Medizin, Staudtstraße 2, Erlangen 91058, Germany
| | - Marcus Keatinge
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Karolina S Mysiak
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK
| | - Beth E P Henderson
- Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Ross Dobie
- Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Neil C Henderson
- Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK; MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Thomas Becker
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK.
| | - Catherina G Becker
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB, UK; Euan MacDonald Centre for Motor Neurone Disease Research University of Edinburgh, Edinburgh, UK.
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22
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Oprişoreanu AM, Smith HL, Krix S, Chaytow H, Carragher NO, Gillingwater TH, Becker CG, Becker T. Automated in vivo drug screen in zebrafish identifies synapse-stabilising drugs with relevance to spinal muscular atrophy. Dis Model Mech 2021; 14:259422. [PMID: 33973627 PMCID: PMC8106959 DOI: 10.1242/dmm.047761] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 03/10/2021] [Indexed: 12/14/2022] Open
Abstract
Synapses are particularly vulnerable in many neurodegenerative diseases and often the first to degenerate, for example in the motor neuron disease spinal muscular atrophy (SMA). Compounds that can counteract synaptic destabilisation are rare. Here, we describe an automated screening paradigm in zebrafish for small-molecule compounds that stabilize the neuromuscular synapse in vivo. We make use of a mutant for the axonal C-type lectin chondrolectin (chodl), one of the main genes dysregulated in SMA. In chodl-/- mutants, neuromuscular synapses that are formed at the first synaptic site by growing axons are not fully mature, causing axons to stall, thereby impeding further axon growth beyond that synaptic site. This makes axon length a convenient read-out for synapse stability. We screened 982 small-molecule compounds in chodl chodl-/- mutants and found four that strongly rescued motor axon length. Aberrant presynaptic neuromuscular synapse morphology was also corrected. The most-effective compound, the adenosine uptake inhibitor drug dipyridamole, also rescued axon growth defects in the UBA1-dependent zebrafish model of SMA. Hence, we describe an automated screening pipeline that can detect compounds with relevance to SMA. This versatile platform can be used for drug and genetic screens, with wider relevance to synapse formation and stabilisation.
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Affiliation(s)
- Ana-Maria Oprişoreanu
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB
| | - Hannah L Smith
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB
| | - Sophia Krix
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB
| | - Helena Chaytow
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, EH16 4SB Edinburgh, UK
| | - Neil O Carragher
- Cancer Research UK Edinburgh Centre, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, EH4 2XR Edinburgh, UK
| | - Thomas H Gillingwater
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, EH16 4SB Edinburgh, UK
| | - Catherina G Becker
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, EH16 4SB Edinburgh, UK
| | - Thomas Becker
- Centre for Discovery Brain Sciences, University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, Edinburgh EH16 4SB
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23
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Kishore S, Cadoff EB, Agha MA, McLean DL. Orderly compartmental mapping of premotor inhibition in the developing zebrafish spinal cord. Science 2020; 370:431-436. [PMID: 33093104 DOI: 10.1126/science.abb4608] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/18/2020] [Indexed: 12/13/2022]
Abstract
In vertebrates, faster movements involve the orderly recruitment of different types of spinal motor neurons. However, it is not known how premotor inhibitory circuits are organized to ensure alternating motor output at different movement speeds. We found that different types of commissural inhibitory interneurons in zebrafish form compartmental microcircuits during development that align inhibitory strength and recruitment order. Axonal microcircuits develop first and provide the most potent premotor inhibition during the fastest movements, followed by perisomatic microcircuits, and then dendritic microcircuits that provide the weakest inhibition during the slowest movements. The conversion of a temporal sequence of neuronal development into a spatial pattern of inhibitory connections provides an "ontogenotopic" solution to the problem of shaping spinal motor output at different speeds of movement.
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Affiliation(s)
- Sandeep Kishore
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Eli B Cadoff
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - Moneeza A Agha
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
| | - David L McLean
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA.
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24
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Dynamic regulation of the cholinergic system in the spinal central nervous system. Sci Rep 2020; 10:15338. [PMID: 32948826 PMCID: PMC7501295 DOI: 10.1038/s41598-020-72524-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/18/2020] [Indexed: 11/22/2022] Open
Abstract
While the role of cholinergic neurotransmission from motoneurons is well established during neuromuscular development, whether it regulates central nervous system development in the spinal cord is unclear. Zebrafish presents a powerful model to investigate how the cholinergic system is set up and evolves during neural circuit formation. In this study, we carried out a detailed spatiotemporal analysis of the cholinergic system in embryonic and larval zebrafish. In 1-day-old embryos, we show that spinal motoneurons express presynaptic cholinergic genes including choline acetyltransferase (chata), vesicular acetylcholine transporters (vachta, vachtb), high-affinity choline transporter (hacta) and acetylcholinesterase (ache), while nicotinic acetylcholine receptor (nAChR) subunits are mainly expressed in interneurons. However, in 3-day-old embryos, we found an unexpected decrease in presynaptic cholinergic transcript expression in a rostral to caudal gradient in the spinal cord, which continued during development. On the contrary, nAChR subunits remained highly expressed throughout the spinal cord. We found that protein and enzymatic activities of presynaptic cholinergic genes were also reduced in the rostral spinal cord. Our work demonstrating that cholinergic genes are initially expressed in the embryonic spinal cord, which is dynamically downregulated during development suggests that cholinergic signaling may play a pivotal role during the formation of intra-spinal locomotor circuit.
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25
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Catela C, Kratsios P. Transcriptional mechanisms of motor neuron development in vertebrates and invertebrates. Dev Biol 2019; 475:193-204. [PMID: 31479648 DOI: 10.1016/j.ydbio.2019.08.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 07/08/2019] [Accepted: 08/29/2019] [Indexed: 02/04/2023]
Abstract
Across phylogeny, motor neurons (MNs) represent a single but often remarkably diverse neuronal class composed of a multitude of subtypes required for vital behaviors, such as eating and locomotion. Over the past decades, seminal studies in multiple model organisms have advanced our molecular understanding of the early steps of MN development, such as progenitor specification and acquisition of MN subtype identity, by revealing key roles for several evolutionarily conserved transcription factors. However, very little is known about the molecular strategies that allow distinct MN subtypes to maintain their identity- and function-defining features during the late steps of development and postnatal life. Here, we provide an overview of invertebrate and vertebrate studies on transcription factor-based strategies that control early and late steps of MN development, aiming to highlight evolutionarily conserved gene regulatory principles necessary for establishment and maintenance of neuronal identity.
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Affiliation(s)
- Catarina Catela
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - Paschalis Kratsios
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA; The Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
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26
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Ganz J, Melancon E, Wilson C, Amores A, Batzel P, Strader M, Braasch I, Diba P, Kuhlman JA, Postlethwait JH, Eisen JS. Epigenetic factors Dnmt1 and Uhrf1 coordinate intestinal development. Dev Biol 2019; 455:473-484. [PMID: 31394080 DOI: 10.1016/j.ydbio.2019.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/05/2019] [Accepted: 08/01/2019] [Indexed: 12/15/2022]
Abstract
Intestinal tract development is a coordinated process involving signaling among the progenitors and developing cells from all three germ layers. Development of endoderm-derived intestinal epithelium has been shown to depend on epigenetic modifications, but whether that is also the case for intestinal tract cell types from other germ layers remains unclear. We found that functional loss of a DNA methylation machinery component, ubiquitin-like protein containing PHD and RING finger domains 1 (uhrf1), leads to reduced numbers of ectoderm-derived enteric neurons and severe disruption of mesoderm-derived intestinal smooth muscle. Genetic chimeras revealed that Uhrf1 functions both cell-autonomously in enteric neuron precursors and cell-non-autonomously in surrounding intestinal cells, consistent with what is known about signaling interactions between these cell types that promote one another's development. Uhrf1 recruits the DNA methyltransferase Dnmt1 to unmethylated DNA during replication. Dnmt1 is also expressed in enteric neurons and smooth muscle progenitors. dnmt1 mutants have fewer enteric neurons and disrupted intestinal smooth muscle compared to wildtypes. Because dnmt1;uhrf1 double mutants have a similar phenotype to dnmt1 and uhrf1 single mutants, Dnmt1 and Uhrf1 must function together during enteric neuron and intestinal muscle development. This work shows that genes controlling epigenetic modifications are important to coordinate intestinal tract development, provides the first demonstration that these genes influence development of the ENS, and advances uhrf1 and dnmt1 as potential new Hirschsprung disease candidates.
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Affiliation(s)
- Julia Ganz
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Ellie Melancon
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Catherine Wilson
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Angel Amores
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Peter Batzel
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Marie Strader
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Ingo Braasch
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Parham Diba
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Julie A Kuhlman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, 50011, USA
| | - John H Postlethwait
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA
| | - Judith S Eisen
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR, 97403, USA.
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27
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Bello-Rojas S, Istrate AE, Kishore S, McLean DL. Central and peripheral innervation patterns of defined axial motor units in larval zebrafish. J Comp Neurol 2019; 527:2557-2572. [PMID: 30919953 DOI: 10.1002/cne.24689] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/20/2019] [Accepted: 03/25/2019] [Indexed: 02/06/2023]
Abstract
Spinal motor neurons and the peripheral muscle fibers they innervate form discrete motor units that execute movements of varying force and speed. Subsets of spinal motor neurons also exhibit axon collaterals that influence motor output centrally. Here, we have used in vivo imaging to anatomically characterize the central and peripheral innervation patterns of axial motor units in larval zebrafish. Using early born "primary" motor neurons and their division of epaxial and hypaxial muscle into four distinct quadrants as a reference, we define three distinct types of later born "secondary" motor units. The largest is "m-type" units, which innervate deeper fast-twitch muscle fibers via medial nerves. Next in size are "ms-type" secondaries, which innervate superficial fast-twitch and slow fibers via medial and septal nerves, followed by "s-type" units, which exclusively innervate superficial slow muscle fibers via septal nerves. All types of secondaries innervate up to four axial quadrants. Central axon collaterals are found in subsets of primaries based on soma position and predominantly in secondary fast-twitch units (m, ms) with increasing likelihood based on number of quadrants innervated. Collaterals are labeled by synaptophysin-tagged fluorescent proteins, but not PSD95, consistent with their output function. Also, PSD95 dendrite labeling reveals that larger motor units receive more excitatory synaptic input. Collaterals are largely restricted to the neuropil, however, perisomatic connections are observed between motor units. These observations suggest that recurrent interactions are dominated by motor neurons recruited during stronger movements and set the stage for functional investigations of recurrent motor circuitry in larval zebrafish.
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Affiliation(s)
- Saul Bello-Rojas
- Interdepartmental Neuroscience Postbaccalaureate Research Education Program, Northwestern University, Evanston, Illinois
| | - Ana E Istrate
- Masters Program in Neurobiology, Northwestern University, Evanston, Illinois
| | - Sandeep Kishore
- Department of Neurobiology, Northwestern University, Evanston, Illinois
| | - David L McLean
- Interdepartmental Neuroscience Postbaccalaureate Research Education Program, Northwestern University, Evanston, Illinois.,Masters Program in Neurobiology, Northwestern University, Evanston, Illinois.,Department of Neurobiology, Northwestern University, Evanston, Illinois
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28
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Preston MA, Finseth LT, Bourne JN, Macklin WB. A novel myelin protein zero transgenic zebrafish designed for rapid readout of in vivo myelination. Glia 2019; 67:650-667. [PMID: 30623975 PMCID: PMC6555554 DOI: 10.1002/glia.23559] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/11/2018] [Accepted: 10/16/2018] [Indexed: 12/14/2022]
Abstract
Demyelination occurs following many neurological insults, most notably in multiple sclerosis (MS). Therapeutics that promote remyelination could slow the neurological decline associated with chronic demyelination; however, in vivo testing of candidate small molecule drugs and signaling cascades known to impact myelination is expensive and labor intensive. Here, we describe the development of a novel zebrafish line which uses the putative promoter of Myelin Protein Zero (mpz), a major structural protein in myelin, to drive expression of Enhanced Green Fluorescent Protein (mEGFP) specifically in the processes and nascent internodes of myelinating glia. We observe that changes in fluorescence intensity in Tg(mpz:mEGFP) larvae are a reliable surrogate for changes in myelin membrane production per se in live larvae following bath application of drugs. These changes in fluorescence are strongly predictive of changes in myelin-specific mRNAs [mpz, 36K and myelin basic protein (mbp)] and protein production (Mbp). Finally, we observe that certain drugs alter nascent internode number and length, impacting the overall amount of myelin membrane synthesized and a number of axons myelinated without significantly changing the number of myelinating oligodendrocytes. These studies demonstrate that the Tg(mpz:mEGFP) reporter line responds effectively to positive and negative small molecule regulators of myelination, and could be useful for identifying candidate drugs that specifically target myelin membrane production in vivo. Combined with high throughput cell-based screening of large chemical libraries and automated imaging systems, this transgenic line is useful for rapid large scale whole animal screening to identify novel myelinating small molecule compounds in vivo.
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Affiliation(s)
- Marnie A Preston
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Lisbet T Finseth
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Jennifer N Bourne
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
| | - Wendy B Macklin
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
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29
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Baeuml SW, Biechl D, Wullimann MF. Adult islet1 Expression Outlines Ventralized Derivatives Along Zebrafish Neuraxis. Front Neuroanat 2019; 13:19. [PMID: 30863287 PMCID: PMC6399416 DOI: 10.3389/fnana.2019.00019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/01/2019] [Indexed: 01/16/2023] Open
Abstract
Signals issued by dorsal roof and ventral floor plates, respectively, underlie the major patterning process of dorsalization and ventralization during vertebrate neural tube development. The ventrally produced morphogen Sonic hedgehog (SHH) is crucial for vertebrate hindbrain and spinal motor neuron development. One diagnostic gene for motor neurons is the LIM/homeodomain gene islet1, which has additional ventral expression domains extending into mid- and forebrain. In order to corroborate motor neuron development and, in particular, to improve on the identification of poorly documented zebrafish forebrain islet1 populations, we studied adult brains of transgenic islet1-GFP zebrafish (3 and 6 months). This molecular neuroanatomical analysis was supported by immunostaining these brains for tyrosine hydroxylase (TH) or choline acetyltransferase (ChAT), respectively, revealing zebrafish catecholaminergic and cholinergic neurons. The present analysis of ChAT and islet1-GFP label confirms ongoing adult expression of islet1 in zebrafish (basal plate) midbrain, hindbrain, and spinal motor neurons. In contrast, non-motor cholinergic systems lack islet1 expression. Additional presumed basal plate islet1 positive systems are described in detail, aided by TH staining which is particularly informative in the diencephalon. Finally, alar plate zebrafish forebrain systems with islet1 expression are described (i.e., thalamus, preoptic region, and subpallium). We conclude that adult zebrafish continue to express islet1 in the same brain systems as in the larva. Further, pending functional confirmation we hypothesize that the larval expression of sonic hedgehog (shh) might causally underlie much of adult islet1 expression because it explains findings beyond ventrally located systems, for example regarding shh expression in the zona limitans intrathalamica and correlated islet1-GFP expression in the thalamus.
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Affiliation(s)
- Stephan W Baeuml
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Daniela Biechl
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mario F Wullimann
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-Universität München, Munich, Germany
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30
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Formella I, Svahn AJ, Radford RAW, Don EK, Cole NJ, Hogan A, Lee A, Chung RS, Morsch M. Real-time visualization of oxidative stress-mediated neurodegeneration of individual spinal motor neurons in vivo. Redox Biol 2018; 19:226-234. [PMID: 30193184 PMCID: PMC6126400 DOI: 10.1016/j.redox.2018.08.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/21/2018] [Accepted: 08/21/2018] [Indexed: 12/13/2022] Open
Abstract
Generation of reactive oxygen species (ROS) has been shown to be important for many physiological processes, ranging from cell differentiation to apoptosis. With the development of the genetically encoded photosensitiser KillerRed (KR) it is now possible to efficiently produce ROS dose-dependently in a specific cell type upon green light illumination. Zebrafish are the ideal vertebrate animal model for these optogenetic methods because of their transparency and efficient transgenesis. Here we describe a zebrafish model that expresses membrane-targeted KR selectively in motor neurons. We show that KR-activated neurons in the spinal cord undergo stress and cell death after induction of ROS. Using single-cell resolution and time-lapse confocal imaging, we selectively induced neurodegeneration in KR-expressing neurons leading to characteristic signs of apoptosis and cell death. We furthermore illustrate a targeted microglia response to the induction site as part of a physiological response within the zebrafish spinal cord. Our data demonstrate the successful implementation of KR mediated ROS toxicity in motor neurons in vivo and has important implications for studying the effects of ROS in a variety of conditions within the central nervous system, including aging and age-related neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Motor neurons can be targeted for oxidative stress using optogenetics in zebrafish. KillerRed expressing neurons undergo characteristic sequence of neurodegeneration. Targeted neurons show microglial activation as part of the physiological response. ROS toxicity has important implications for mechanisms driving neurodegeneration.
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Affiliation(s)
- Isabel Formella
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Adam J Svahn
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Rowan A W Radford
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Emily K Don
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Nicholas J Cole
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Alison Hogan
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Albert Lee
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Roger S Chung
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia.
| | - Marco Morsch
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, New South Wales, Australia.
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31
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D'Elia KP, Dasen JS. Development, functional organization, and evolution of vertebrate axial motor circuits. Neural Dev 2018; 13:10. [PMID: 29855378 PMCID: PMC5984435 DOI: 10.1186/s13064-018-0108-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 04/26/2018] [Indexed: 12/20/2022] Open
Abstract
Neuronal control of muscles associated with the central body axis is an ancient and essential function of the nervous systems of most animal species. Throughout the course of vertebrate evolution, motor circuits dedicated to control of axial muscle have undergone significant changes in their roles within the motor system. In most fish species, axial circuits are critical for coordinating muscle activation sequences essential for locomotion and play important roles in postural correction. In tetrapods, axial circuits have evolved unique functions essential to terrestrial life, including maintaining spinal alignment and breathing. Despite the diverse roles of axial neural circuits in motor behaviors, the genetic programs underlying their assembly are poorly understood. In this review, we describe recent studies that have shed light on the development of axial motor circuits and compare and contrast the strategies used to wire these neural networks in aquatic and terrestrial vertebrate species.
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Affiliation(s)
- Kristen P D'Elia
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY, 10016, USA
| | - Jeremy S Dasen
- Neuroscience Institute, Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY, 10016, USA.
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32
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Fowler DK, Stewart S, Seredick S, Eisen JS, Stankunas K, Washbourne P. A MultiSite Gateway Toolkit for Rapid Cloning of Vertebrate Expression Constructs with Diverse Research Applications. PLoS One 2016; 11:e0159277. [PMID: 27500400 PMCID: PMC4976983 DOI: 10.1371/journal.pone.0159277] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 06/29/2016] [Indexed: 11/19/2022] Open
Abstract
Recombination-based cloning is a quick and efficient way to generate expression vectors. Recent advancements have provided powerful recombinant DNA methods for molecular manipulations. Here, we describe a novel collection of three-fragment MultiSite Gateway cloning system-compatible vectors providing expanded molecular tools for vertebrate research. The components of this toolkit encompass a broad range of uses such as fluorescent imaging, dual gene expression, RNA interference, tandem affinity purification, chemically-inducible dimerization and lentiviral production. We demonstrate examples highlighting the utility of this toolkit for producing multi-component vertebrate expression vectors with diverse primary research applications. The vectors presented here are compatible with other Gateway toolkits and collections, facilitating the rapid generation of a broad range of innovative DNA constructs for biological research.
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Affiliation(s)
- Daniel K. Fowler
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Scott Stewart
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Steve Seredick
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Judith S. Eisen
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Kryn Stankunas
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Philip Washbourne
- Institute of Neuroscience, Department of Biology, University of Oregon, Eugene, Oregon, United States of America
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33
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Johnson K, Barragan J, Bashiruddin S, Smith CJ, Tyrrell C, Parsons MJ, Doris R, Kucenas S, Downes GB, Velez CM, Schneider C, Sakai C, Pathak N, Anderson K, Stein R, Devoto SH, Mumm JS, Barresi MJF. Gfap-positive radial glial cells are an essential progenitor population for later-born neurons and glia in the zebrafish spinal cord. Glia 2016; 64:1170-89. [PMID: 27100776 PMCID: PMC4918407 DOI: 10.1002/glia.22990] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 11/12/2022]
Abstract
Radial glial cells are presumptive neural stem cells (NSCs) in the developing nervous system. The direct requirement of radial glia for the generation of a diverse array of neuronal and glial subtypes, however, has not been tested. We employed two novel transgenic zebrafish lines and endogenous markers of NSCs and radial glia to show for the first time that radial glia are essential for neurogenesis during development. By using the gfap promoter to drive expression of nuclear localized mCherry we discerned two distinct radial glial-derived cell types: a major nestin+/Sox2+ subtype with strong gfap promoter activity and a minor Sox2+ subtype lacking this activity. Fate mapping studies in this line indicate that gfap+ radial glia generate later-born CoSA interneurons, secondary motorneurons, and oligodendroglia. In another transgenic line using the gfap promoter-driven expression of the nitroreductase enzyme, we induced cell autonomous ablation of gfap+ radial glia and observed a reduction in their specific derived lineages, but not Blbp+ and Sox2+/gfap-negative NSCs, which were retained and expanded at later larval stages. Moreover, we provide evidence supporting classical roles of radial glial in axon patterning, blood-brain barrier formation, and locomotion. Our results suggest that gfap+ radial glia represent the major NSC during late neurogenesis for specific lineages, and possess diverse roles to sustain the structure and function of the spinal cord. These new tools will both corroborate the predicted roles of astroglia and reveal novel roles related to development, physiology, and regeneration in the vertebrate nervous system. GLIA 2016;64:1170-1189.
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Affiliation(s)
- Kimberly Johnson
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts
| | - Jessica Barragan
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Sarah Bashiruddin
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Cody J Smith
- Department of Biology, University of Virginia, Charlottesville, Virginia
| | - Chelsea Tyrrell
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
| | - Michael J Parsons
- Department of Surgery, Johns Hopkins University, Baltimore, Maryland
| | - Rosemarie Doris
- Department of Biology, Wesleyan University, Middletown, Connecticut
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, Virginia
| | - Gerald B Downes
- Department of Biology, University of Massachusetts, Amherst, Massachusetts
| | - Carla M Velez
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Caitlin Schneider
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Catalina Sakai
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Narendra Pathak
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Katrina Anderson
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Rachael Stein
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
| | - Stephen H Devoto
- Department of Biology, Wesleyan University, Middletown, Connecticut
| | - Jeff S Mumm
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland
| | - Michael J F Barresi
- Department of Biological Sciences, Smith College, Northampton, Massachusetts
- Molecular and Cellular Biology Program, University of Massachusetts, Amherst, Massachusetts
- Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
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34
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Ott E, Wendik B, Srivastava M, Pacho F, Töchterle S, Salvenmoser W, Meyer D. Pronephric tubule morphogenesis in zebrafish depends on Mnx mediated repression of irx1b within the intermediate mesoderm. Dev Biol 2015; 411:101-14. [PMID: 26472045 DOI: 10.1016/j.ydbio.2015.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 09/21/2015] [Accepted: 10/09/2015] [Indexed: 12/11/2022]
Abstract
Mutations in the homeobox transcription factor MNX1 are the major cause of dominantly inherited sacral agenesis. Studies in model organisms revealed conserved mnx gene requirements in neuronal and pancreatic development while Mnx activities that could explain the caudal mesoderm specific agenesis phenotype remain elusive. Here we use the zebrafish pronephros as a simple yet genetically conserved model for kidney formation to uncover a novel role of Mnx factors in nephron morphogenesis. Pronephros formation can formally be divided in four stages, the specification of nephric mesoderm from the intermediate mesoderm (IM), growth and epithelialisation, segmentation and formation of the glomerular capillary tuft. Two of the three mnx genes in zebrafish are dynamically transcribed in caudal IM in a time window that proceeds segmentation. We show that expression of one mnx gene, mnx2b, is restricted to the pronephric lineage and that mnx2b knock-down causes proximal pronephric tubule dilation and impaired pronephric excretion. Using expression profiling of embryos transgenic for conditional activation and repression of Mnx regulated genes, we further identified irx1b as a direct target of Mnx factors. Consistent with a repression of irx1b by Mnx factors, the transcripts of irx1b and mnx genes are found in mutual exclusive regions in the IM, and blocking of Mnx functions results in a caudal expansion of the IM-specific irx1b expression. Finally, we find that knock-down of irx1b is sufficient to rescue proximal pronephric tubule dilation and impaired nephron function in mnx-morpholino injected embryos. Our data revealed a first caudal mesoderm specific requirement of Mnx factors in a non-human system and they demonstrate that Mnx-dependent restriction of IM-specific irx1b activation is required for the morphogenesis and function of the zebrafish pronephros.
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Affiliation(s)
- Elisabeth Ott
- Institute for Molecular Biology/CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
| | - Björn Wendik
- Developmental Biology, Institute Biology 1, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany.
| | - Monika Srivastava
- Developmental Biology, Institute Biology 1, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany.
| | - Frederic Pacho
- Institute for Molecular Biology/CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
| | - Sonja Töchterle
- Institute for Molecular Biology/CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
| | - Willi Salvenmoser
- Institute of Zoology/CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
| | - Dirk Meyer
- Institute for Molecular Biology/CMBI, University of Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria.
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35
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Stil A, Drapeau P. Neuronal labeling patterns in the spinal cord of adult transgenic Zebrafish. Dev Neurobiol 2015; 76:642-60. [PMID: 26408263 DOI: 10.1002/dneu.22350] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 09/13/2015] [Accepted: 09/14/2015] [Indexed: 01/20/2023]
Abstract
We describe neuronal patterns in the spinal cord of adult zebrafish. We studied the distribution of cells and processes in the three spinal regions reported in the literature: the 8th vertebra used as a transection injury site, the 15th vertebra mainly used for motor cell recordings and also for crush injury, and the 24th vertebra used to record motor nerve activity. We used well-known transgenic lines in which expression of green fluorescent protein (GFP) is driven by promoters to hb9 and isl1 in motoneurons, alx/chx10 and evx1 interneurons, ngn1 in sensory neurons and olig2 in oligodendrocytes, as well as antibodies for neurons (HuC/D, NF and SV2) and glia (GFAP). In isl1:GFP fish, GFP-positive processes are retained in the upper part of ventral horns and two subsets of cell bodies are observed. The pattern of the transgene in hb9:GFP adults is more diffuse and fibers are present broadly through the adult spinal cord. In alx/chx10 and evx1 lines we respectively observed two and three different GFP-positive populations. Finally, the ngn1:GFP transgene identifies dorsal root ganglion and some cells in dorsal horns. Interestingly some GFP positive fibers in ngn1:GFP fish are located around Mauthner axons and their density seems to be related to a rostrocaudal gradient. Many other cell types have been described in embryos and need to be studied in adults. Our findings provide a reference for further studies on spinal cytoarchitecture. Combined with physiological, histological and pathological/traumatic approaches, these studies will help clarify the operation of spinal locomotor circuits of adult zebrafish.
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Affiliation(s)
- Aurélie Stil
- Hospital Research Centre (CRCHUM) and Department of Neurosciences, Université de Montréal, Montréal, Quebec, Canada, H2X 0A9
| | - Pierre Drapeau
- Hospital Research Centre (CRCHUM) and Department of Neurosciences, Université de Montréal, Montréal, Quebec, Canada, H2X 0A9
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36
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Abstract
Evolutionary modifications in nervous systems enabled organisms to adapt to their specific environments and underlie the remarkable diversity of behaviors expressed by animals. Resolving the pathways that shaped and modified neural circuits during evolution remains a significant challenge. Comparative studies have revealed a surprising conservation in the intrinsic signaling systems involved in early patterning of bilaterian nervous systems but also raise the question of how neural circuit compositions and architectures evolved within specific animal lineages. In this review, we discuss the mechanisms that contributed to the emergence and diversity of animal nervous systems, focusing on the circuits governing vertebrate locomotion.
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Affiliation(s)
- Heekyung Jung
- Howard Hughes Medical Institute (HHMI), NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA
| | - Jeremy S Dasen
- Howard Hughes Medical Institute (HHMI), NYU Neuroscience Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY 10016, USA.
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Generation of BAC transgenic tadpoles enabling live imaging of motoneurons by using the urotensin II-related peptide (ust2b) gene as a driver. PLoS One 2015; 10:e0117370. [PMID: 25658845 PMCID: PMC4319907 DOI: 10.1371/journal.pone.0117370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 12/22/2014] [Indexed: 12/13/2022] Open
Abstract
Xenopus is an excellent tetrapod model for studying normal and pathological motoneuron ontogeny due to its developmental morpho-physiological advantages. In mammals, the urotensin II-related peptide (UTS2B) gene is primarily expressed in motoneurons of the brainstem and the spinal cord. Here, we show that this expression pattern was conserved in Xenopus and established during the early embryonic development, starting at the early tailbud stage. In late tadpole stage, uts2b mRNA was detected both in the hindbrain and in the spinal cord. Spinal uts2b+ cells were identified as axial motoneurons. In adult, however, the uts2b expression was only detected in the hindbrain. We assessed the ability of the uts2b promoter to drive the expression of a fluorescent reporter in motoneurons by recombineering a green fluorescent protein (GFP) into a bacterial artificial chromosome (BAC) clone containing the entire X. tropicalis uts2b locus. After injection of this construction in one-cell stage embryos, a transient GFP expression was observed in the spinal cord of about a quarter of the resulting animals from the early tailbud stage and up to juveniles. The GFP expression pattern was globally consistent with that of the endogenous uts2b in the spinal cord but no fluorescence was observed in the brainstem. A combination of histological and electrophysiological approaches was employed to further characterize the GFP+ cells in the larvae. More than 98% of the GFP+ cells expressed choline acetyltransferase, while their projections were co-localized with α-bungarotoxin labeling. When tail myotomes were injected with rhodamine dextran amine crystals, numerous double-stained GFP+ cells were observed. In addition, intracellular electrophysiological recordings of GFP+ neurons revealed locomotion-related rhythmic discharge patterns during fictive swimming. Taken together our results provide evidence that uts2b is an appropriate driver to express reporter genes in larval motoneurons of the Xenopus spinal cord.
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Seredick S, Hutchinson SA, Van Ryswyk L, Talbot JC, Eisen JS. Lhx3 and Lhx4 suppress Kolmer-Agduhr interneuron characteristics within zebrafish axial motoneurons. Development 2014; 141:3900-9. [PMID: 25231761 DOI: 10.1242/dev.105718] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A central problem in development is how fates of closely related cells are segregated. Lineally related motoneurons (MNs) and interneurons (INs) express many genes in common yet acquire distinct fates. For example, in mouse and chick Lhx3 plays a pivotal role in the development of both cell classes. Here, we utilize the ability to recognize individual zebrafish neurons to examine the roles of Lhx3 and its paralog Lhx4 in the development of MNs and ventral INs. We show that Lhx3 and Lhx4 are expressed by post-mitotic axial MNs derived from the MN progenitor (pMN) domain, p2 domain progenitors and by several types of INs derived from pMN and p2 domains. In the absence of Lhx3 and Lhx4, early-developing primary MNs (PMNs) adopt a hybrid fate, with morphological and molecular features of both PMNs and pMN-derived Kolmer-Agduhr' (KA') INs. In addition, we show that Lhx3 and Lhx4 distinguish the fates of two pMN-derived INs. Finally, we demonstrate that Lhx3 and Lhx4 are necessary for the formation of late-developing V2a and V2b INs. In conjunction with our previous work, these data reveal that distinct transcription factor families are deployed in post-mitotic MNs to unequivocally assign MN fate and suppress the development of alternative pMN-derived IN fates.
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Affiliation(s)
- Steve Seredick
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA
| | - Sarah A Hutchinson
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA
| | - Liesl Van Ryswyk
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA
| | - Jared C Talbot
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA
| | - Judith S Eisen
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA
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Carlisle TC, Ribera AB. Connexin 35b expression in the spinal cord of Danio rerio embryos and larvae. J Comp Neurol 2014; 522:861-75. [PMID: 23939687 DOI: 10.1002/cne.23449] [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: 05/14/2013] [Revised: 07/10/2013] [Accepted: 08/02/2013] [Indexed: 11/11/2022]
Abstract
Electrical synapses are expressed prominently in the developing and mature nervous systems. Unlike chemical synapses, little is known about the developmental role of electrical synapses, reflecting the limitations imposed by the lack of selective pharmacological blockers. At a molecular level, the building blocks of electrical synapses are connexin proteins. In this study, we report the expression pattern for neuronally expressed connexin 35b (cx35b), the zebrafish orthologue of mammalian connexin (Cx) 36. We find that cx35b is expressed at the time of neural induction, indicating a possible early role in neural progenitor cells. Additionally, cx35b localizes to the ventral spinal cord during embryonic and early larval stages. We detect cx35b mRNA in secondary motor neurons (SMNs) and interneurons. We identified the premotor circumferential descending (CiD) interneuron as one interneuron subtype expressing cx35b. In addition, cx35b is present in other ventral interneurons of unknown subtype(s). This early expression of cx35b in SMNs and CiDs suggests a possible role in motor network function during embryonic and larval stages.
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Affiliation(s)
- Tara C Carlisle
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Colorado Clinical and Translational Sciences Institute, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045; Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045
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Moreno RL, Ribera AB. Spinal neurons require Islet1 for subtype-specific differentiation of electrical excitability. Neural Dev 2014; 9:19. [PMID: 25149090 PMCID: PMC4153448 DOI: 10.1186/1749-8104-9-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 07/16/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the spinal cord, stereotypic patterns of transcription factor expression uniquely identify neuronal subtypes. These transcription factors function combinatorially to regulate gene expression. Consequently, a single transcription factor may regulate divergent development programs by participation in different combinatorial codes. One such factor, the LIM-homeodomain transcription factor Islet1, is expressed in the vertebrate spinal cord. In mouse, chick and zebrafish, motor and sensory neurons require Islet1 for specification of biochemical and morphological signatures. Little is known, however, about the role that Islet1 might play for development of electrical membrane properties in vertebrates. Here we test for a role of Islet1 in differentiation of excitable membrane properties of zebrafish spinal neurons. RESULTS We focus our studies on the role of Islet1 in two populations of early born zebrafish spinal neurons: ventral caudal primary motor neurons (CaPs) and dorsal sensory Rohon-Beard cells (RBs). We take advantage of transgenic lines that express green fluorescent protein (GFP) to identify CaPs, RBs and several classes of interneurons for electrophysiological study. Upon knock-down of Islet1, cells occupying CaP-like and RB-like positions continue to express GFP. With respect to voltage-dependent currents, CaP-like and RB-like neurons have novel repertoires that distinguish them from control CaPs and RBs, and, in some respects, resemble those of neighboring interneurons. The action potentials fired by CaP-like and RB-like neurons also have significantly different properties compared to those elicited from control CaPs and RBs. CONCLUSIONS Overall, our findings suggest that, for both ventral motor and dorsal sensory neurons, Islet1 directs differentiation programs that ultimately specify electrical membrane as well as morphological properties that act together to sculpt neuron identity.
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Affiliation(s)
- Rosa L Moreno
- Department of Physiology, University of Colorado Anschutz Medical Campus, RC-1 North, 7403A, Mailstop 8307, 12800 E 19th Ave,, 80045 Aurora, CO, USA.
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Babin PJ, Goizet C, Raldúa D. Zebrafish models of human motor neuron diseases: advantages and limitations. Prog Neurobiol 2014; 118:36-58. [PMID: 24705136 DOI: 10.1016/j.pneurobio.2014.03.001] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/11/2014] [Accepted: 03/14/2014] [Indexed: 01/08/2023]
Abstract
Motor neuron diseases (MNDs) are an etiologically heterogeneous group of disorders of neurodegenerative origin, which result in degeneration of lower (LMNs) and/or upper motor neurons (UMNs). Neurodegenerative MNDs include pure hereditary spastic paraplegia (HSP), which involves specific degeneration of UMNs, leading to progressive spasticity of the lower limbs. In contrast, spinal muscular atrophy (SMA) involves the specific degeneration of LMNs, with symmetrical muscle weakness and atrophy. Amyotrophic lateral sclerosis (ALS), the most common adult-onset MND, is characterized by the degeneration of both UMNs and LMNs, leading to progressive muscle weakness, atrophy, and spasticity. A review of the comparative neuroanatomy of the human and zebrafish motor systems showed that, while the zebrafish was a homologous model for LMN disorders, such as SMA, it was only partially relevant in the case of UMN disorders, due to the absence of corticospinal and rubrospinal tracts in its central nervous system. Even considering the limitation of this model to fully reproduce the human UMN disorders, zebrafish offer an excellent alternative vertebrate model for the molecular and genetic dissection of MND mechanisms. Its advantages include the conservation of genome and physiological processes and applicable in vivo tools, including easy imaging, loss or gain of function methods, behavioral tests to examine changes in motor activity, and the ease of simultaneous chemical/drug testing on large numbers of animals. This facilitates the assessment of the environmental origin of MNDs, alone or in combination with genetic traits and putative modifier genes. Positive hits obtained by phenotype-based small-molecule screening using zebrafish may potentially be effective drugs for treatment of human MNDs.
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Affiliation(s)
- Patrick J Babin
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France.
| | - Cyril Goizet
- Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576, Talence, France; CHU Bordeaux, Hôpital Pellegrin, Service de Génétique Médicale, Bordeaux, France
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The role of inab in axon morphology of an identified zebrafish motoneuron. PLoS One 2014; 9:e88631. [PMID: 24533123 PMCID: PMC3922942 DOI: 10.1371/journal.pone.0088631] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 01/15/2014] [Indexed: 12/15/2022] Open
Abstract
The ability of an animal to move and to interact with its environment requires that motoneurons correctly innervate specific muscles. Although many genes that regulate motoneuron development have been identified, our understanding of motor axon branching remains incomplete. We used transcriptional expression profiling to identify potential candidate genes involved in development of zebrafish identified motoneurons. Here we focus on inab, an intermediate filament encoding gene dynamically expressed in a subset of motoneurons as well as in an identified interneuron. We show that inab is necessary for proper axon morphology of a specific motoneuron subtype.
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Johnson K, Moriarty C, Tania N, Ortman A, DiPietrantonio K, Edens B, Eisenman J, Ok D, Krikorian S, Barragan J, Golé C, Barresi MJF. Kif11 dependent cell cycle progression in radial glial cells is required for proper neurogenesis in the zebrafish neural tube. Dev Biol 2013; 387:73-92. [PMID: 24370453 DOI: 10.1016/j.ydbio.2013.12.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 10/25/2022]
Abstract
Radial glia serve as the resident neural stem cells in the embryonic vertebrate nervous system, and their proliferation must be tightly regulated to generate the correct number of neuronal and glial cell progeny in the neural tube. During a forward genetic screen, we recently identified a zebrafish mutant in the kif11 loci that displayed a significant increase in radial glial cell bodies at the ventricular zone of the spinal cord. Kif11, also known as Eg5, is a kinesin-related, plus-end directed motor protein responsible for stabilizing and separating the bipolar mitotic spindle. We show here that Gfap+ radial glial cells express kif11 in the ventricular zone and floor plate. Loss of Kif11 by mutation or pharmacological inhibition with S-trityl-L-cysteine (STLC) results in monoastral spindle formation in radial glial cells, which is characteristic of mitotic arrest. We show that M-phase radial glia accumulate over time at the ventricular zone in kif11 mutants and STLC treated embryos. Mathematical modeling of the radial glial accumulation in kif11 mutants not only confirmed an ~226× delay in mitotic exit (likely a mitotic arrest), but also predicted two modes of increased cell death. These modeling predictions were supported by an increase in the apoptosis marker, anti-activated Caspase-3, which was also found to be inversely proportional to a decrease in cell proliferation. In addition, treatment with STLC at different stages of neural development uncovered two critical periods that most significantly require Kif11 function for stem cell progression through mitosis. We also show that loss of Kif11 function causes specific reductions in oligodendroglia and secondary interneurons and motorneurons, suggesting these later born populations require proper radial glia division. Despite these alterations to cell cycle dynamics, survival, and neurogenesis, we document unchanged cell densities within the neural tube in kif11 mutants, suggesting that a mechanism of compensatory regulation may exist to maintain overall proportions in the neural tube. We propose a model in which Kif11 normally functions during mitotic spindle formation to facilitate the progression of radial glia through mitosis, which leads to the maturation of progeny into specific secondary neuronal and glial lineages in the developing neural tube.
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Affiliation(s)
- Kimberly Johnson
- Biological Sciences, Smith College, Northampton, MA 01063, United States; Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, United States
| | - Chelsea Moriarty
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Nessy Tania
- Mathematics and Statistics, Smith College, Northampton, MA 01063, United States
| | - Alissa Ortman
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | | | - Brittany Edens
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Jean Eisenman
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Deborah Ok
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Sarah Krikorian
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Jessica Barragan
- Biological Sciences, Smith College, Northampton, MA 01063, United States
| | - Christophe Golé
- Mathematics and Statistics, Smith College, Northampton, MA 01063, United States
| | - Michael J F Barresi
- Biological Sciences, Smith College, Northampton, MA 01063, United States; Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, United States.
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Asakawa K, Abe G, Kawakami K. Cellular dissection of the spinal cord motor column by BAC transgenesis and gene trapping in zebrafish. Front Neural Circuits 2013; 7:100. [PMID: 23754985 PMCID: PMC3664770 DOI: 10.3389/fncir.2013.00100] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 05/04/2013] [Indexed: 11/13/2022] Open
Abstract
Bacterial artificial chromosome (BAC) transgenesis and gene/enhancer trapping are effective approaches for identification of genetically defined neuronal populations in the central nervous system (CNS). Here, we applied these techniques to zebrafish (Danio rerio) in order to obtain insights into the cellular architecture of the axial motor column in vertebrates. First, by using the BAC for the Mnx class homeodomain protein gene mnr2b/mnx2b, we established the mnGFF7 transgenic line expressing the Gal4FF transcriptional activator in a large part of the motor column. Single cell labeling of Gal4FF-expressing cells in the mnGFF7 line enabled a detailed investigation of the morphological characteristics of individual spinal motoneurons, as well as the overall organization of the motor column in a spinal segment. Secondly, from a large-scale gene trap screen, we identified transgenic lines that marked discrete subpopulations of spinal motoneurons with Gal4FF. Molecular characterization of these lines led to the identification of the ADAMTS3 gene, which encodes an evolutionarily conserved ADAMTS family of peptidases and is dynamically expressed in the ventral spinal cord. The transgenic fish established here, along with the identified gene, should facilitate an understanding of the cellular and molecular architecture of the spinal cord motor column and its connection to muscles in vertebrates.
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Affiliation(s)
- Kazuhide Asakawa
- Department of Developmental Genetics, Division of Molecular and Developmental Biology, National Institute of Genetics Mishima, Shizuoka, Japan ; Department of Genetics, Graduate University for Advanced Studies (SOKENDAI) Mishima, Shizuoka, Japan
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