1
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Liu KE, Kucenas S. Rohon-beard neurons do not succumb to programmed cell death during zebrafish development. Dev Biol 2024:S0012-1606(24)00170-2. [PMID: 38944329 DOI: 10.1016/j.ydbio.2024.06.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 06/21/2024] [Accepted: 06/24/2024] [Indexed: 07/01/2024]
Abstract
During neural development, sculpting of early formed circuits by cell death and synaptic pruning is necessary to generate a functional and efficient nervous system. This allows for the establishment of rudimentary circuits which necessitate early organism survival to later undergo subsequent refinement. These changes facilitate additional specificity to stimuli which can lead to increased behavioral complexity. In multiple species, Rohon-Beard neurons (RBs) are the earliest mechanosensory neurons specified and are critical in establishing a rudimentary motor response circuit. Sensory input from RBs gradually becomes redundant as dorsal root ganglion (DRG) neurons develop and integrate into motor circuits. Previous studies demonstrate that RBs undergo a dramatic wave of cell death concurrent with development of the DRG. However, contrary to these studies, we show that neurogenin1+ (ngn1) RBs do not undergo a widespread wave of programmed cell death during early zebrafish development and instead persist until at least 15 days post fertilization (dpf). Starting at 2 dpf, we also observed a dramatic medialization and shrinkage of ngn1+ RB somas along with a gradual downregulation of ngn1 in RBs. This alters a fundamental premise of early zebrafish neural development and opens new avenues to explore mechanisms of RB function, persistence, and circuit refinement.
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Affiliation(s)
- Kendra E Liu
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, 22904, USA; Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, 22904, USA
| | - Sarah Kucenas
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA, 22904, USA; Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA; Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, 22904, USA.
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2
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Akbari N, Tatarsky RL, Kolkman KE, Fetcho JR, Xu C, Bass AH. Label-free, whole-brain in vivo mapping in an adult vertebrate with third harmonic generation microscopy. J Comp Neurol 2024; 532:e25614. [PMID: 38616537 PMCID: PMC11069316 DOI: 10.1002/cne.25614] [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: 06/14/2023] [Revised: 02/16/2024] [Accepted: 03/24/2024] [Indexed: 04/16/2024]
Abstract
Comprehensive understanding of interconnected networks within the brain requires access to high resolution information within large field of views and over time. Currently, methods that enable mapping structural changes of the entire brain in vivo are extremely limited. Third harmonic generation (THG) can resolve myelinated structures, blood vessels, and cell bodies throughout the brain without the need for any exogenous labeling. Together with deep penetration of long wavelengths, this enables in vivo brain-mapping of large fractions of the brain in small animals and over time. Here, we demonstrate that THG microscopy allows non-invasive label-free mapping of the entire brain of an adult vertebrate, Danionella dracula, which is a miniature species of cyprinid fish. We show this capability in multiple brain regions and in particular the identification of major commissural fiber bundles in the midbrain and the hindbrain. These features provide readily discernable landmarks for navigation and identification of regional-specific neuronal groups and even single neurons during in vivo experiments. We further show how this label-free technique can easily be coupled with fluorescence microscopy and used as a comparative tool for studies of other species with similar body features to Danionella, such as zebrafish (Danio rerio) and tetras (Trochilocharax ornatus). This new evidence, building on previous studies, demonstrates how small size and relative transparency, combined with the unique capabilities of THG microscopy, can enable label-free access to the entire adult vertebrate brain.
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Affiliation(s)
- Najva Akbari
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY USA 14850
- Present address: Department of Biology, Stanford University, Stanford, CA USA 94305
| | - Rose L. Tatarsky
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY USA 14850
| | - Kristine E. Kolkman
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY USA 14850
| | - Joseph R. Fetcho
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY USA 14850
| | - Chris Xu
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY USA 14850
| | - Andrew H. Bass
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY USA 14850
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3
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Hsu LJ, Bertho M, Kiehn O. Deconstructing the modular organization and real-time dynamics of mammalian spinal locomotor networks. Nat Commun 2023; 14:873. [PMID: 36797254 PMCID: PMC9935527 DOI: 10.1038/s41467-023-36587-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/07/2023] [Indexed: 02/18/2023] Open
Abstract
Locomotion empowers animals to move. Locomotor-initiating signals from the brain are funneled through descending neurons in the brainstem that act directly on spinal locomotor circuits. Little is known in mammals about which spinal circuits are targeted by the command and how this command is transformed into rhythmicity in the cord. Here we address these questions leveraging a mouse brainstem-spinal cord preparation from either sex that allows locating the locomotor command neurons with simultaneous Ca2+ imaging of spinal neurons. We show that a restricted brainstem area - encompassing the lateral paragigantocellular nucleus (LPGi) and caudal ventrolateral reticular nucleus (CVL) - contains glutamatergic neurons which directly initiate locomotion. Ca2+ imaging captures the direct LPGi/CVL locomotor initiating command in the spinal cord and visualizes spinal glutamatergic modules that execute the descending command and its transformation into rhythmic locomotor activity. Inhibitory spinal networks are recruited in a distinctly different pattern. Our study uncovers the principal logic of how spinal circuits implement the locomotor command using a distinct modular organization.
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Affiliation(s)
- Li-Ju Hsu
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark.,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Maëlle Bertho
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark.,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ole Kiehn
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
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4
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Lescouzères L, Bordignon B, Bomont P. Development of a high-throughput tailored imaging method in zebrafish to understand and treat neuromuscular diseases. Front Mol Neurosci 2022; 15:956582. [PMID: 36204134 PMCID: PMC9530744 DOI: 10.3389/fnmol.2022.956582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
The zebrafish (Danio rerio) is a vertebrate species offering multitude of advantages for the study of conserved biological systems in human and has considerably enriched our knowledge in developmental biology and physiology. Being equally important in medical research, the zebrafish has become a critical tool in the fields of diagnosis, gene discovery, disease modeling, and pharmacology-based therapy. Studies on the zebrafish neuromuscular system allowed for deciphering key molecular pathways in this tissue, and established it as a model of choice to study numerous motor neurons, neuromuscular junctions, and muscle diseases. Starting with the similarities of the zebrafish neuromuscular system with the human system, we review disease models associated with the neuromuscular system to focus on current methodologies employed to study them and outline their caveats. In particular, we put in perspective the necessity to develop standardized and high-resolution methodologies that are necessary to deepen our understanding of not only fundamental signaling pathways in a healthy tissue but also the changes leading to disease phenotype outbreaks, and offer templates for high-content screening strategies. While the development of high-throughput methodologies is underway for motility assays, there is no automated approach to quantify the key molecular cues of the neuromuscular junction. Here, we provide a novel high-throughput imaging methodology in the zebrafish that is standardized, highly resolutive, quantitative, and fit for drug screening. By providing a proof of concept for its robustness in identifying novel molecular players and therapeutic drugs in giant axonal neuropathy (GAN) disease, we foresee that this new tool could be useful for both fundamental and biomedical research.
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Affiliation(s)
- Léa Lescouzères
- ERC Team, Institut NeuroMyoGéne-PGNM, Inserm U1315, CNRS UMR 5261, Claude Bernard University Lyon 1, Lyon, France
| | - Benoît Bordignon
- Montpellier Ressources Imagerie, BioCampus, CNRS, INSERM, University of Montpellier, Montpellier, France
| | - Pascale Bomont
- ERC Team, Institut NeuroMyoGéne-PGNM, Inserm U1315, CNRS UMR 5261, Claude Bernard University Lyon 1, Lyon, France
- *Correspondence: Pascale Bomont,
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5
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Nelson JC, Granato M. Zebrafish behavior as a gateway to nervous system assembly and plasticity. Development 2022; 149:275367. [PMID: 35552393 PMCID: PMC9148562 DOI: 10.1242/dev.177998] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nervous system assembly relies on a diversity of cellular processes ranging from dramatic tissue reorganization to local, subcellular changes all driven by precise molecular programs. Combined, these processes culminate in an animal's ability to plan and execute behaviors. Animal behavior can, therefore, serve as a functional readout of nervous system development. Benefitting from an expansive and growing set of molecular and imaging tools paired with an ever-growing number of assays of diverse behaviors, the zebrafish system has emerged as an outstanding platform at the intersection of nervous system assembly, plasticity and behavior. Here, we summarize recent advancements in the field, including how developing neural circuits are refined to shape complex behaviors and plasticity.
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Affiliation(s)
- Jessica C. Nelson
- Department of Cell and Developmental Biology, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA,Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 421 Curie Blvd, Philadelphia, PA 19104, USA,Authors for correspondence (; )
| | - Michael Granato
- Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, 421 Curie Blvd, Philadelphia, PA 19104, USA,Authors for correspondence (; )
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6
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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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7
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Satou C, Sugioka T, Uemura Y, Shimazaki T, Zmarz P, Kimura Y, Higashijima SI. Functional Diversity of Glycinergic Commissural Inhibitory Neurons in Larval Zebrafish. Cell Rep 2021; 30:3036-3050.e4. [PMID: 32130905 DOI: 10.1016/j.celrep.2020.02.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 12/17/2019] [Accepted: 02/04/2020] [Indexed: 01/16/2023] Open
Abstract
Commissural inhibitory neurons in the spinal cord of aquatic vertebrates coordinate left-right body alternation during swimming. Their developmental origin, however, has been elusive. We investigate this by comparing the anatomy and function of two commissural inhibitory neuron types, dI6dmrt3a and V0d, derived from the pd6 and p0 progenitor domains, respectively. We find that both of these commissural neuron types have monosynaptic, inhibitory connections to neuronal populations active during fictive swimming, supporting their role in providing inhibition to the contralateral side. V0d neurons tend to fire during faster and stronger movements, while dI6dmrt3a neurons tend to fire more consistently during normal fictive swimming. Ablation of dI6dmrt3a neurons leads to an impairment of left-right alternating activity through abnormal co-activation of ventral root neurons on both sides of the spinal cord. Our results suggest that dI6dmrt3a and V0d commissural inhibitory neurons synergistically provide inhibition to the opposite side across different swimming behaviors.
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Affiliation(s)
- Chie Satou
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan.
| | - Takumi Sugioka
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; Graduate University for Advanced Studies, Okazaki, Aichi 444-8787, Japan
| | - Yuto Uemura
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Takashi Shimazaki
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
| | - Pawel Zmarz
- Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, MA, 02138, USA
| | - Yukiko Kimura
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; Graduate University for Advanced Studies, Okazaki, Aichi 444-8787, Japan.
| | - Shin-Ichi Higashijima
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; Graduate University for Advanced Studies, Okazaki, Aichi 444-8787, Japan.
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8
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Meade ME, Roginsky JE, Schulz JR. Primary cell culture of adult zebrafish spinal neurons for electrophysiological studies. J Neurosci Methods 2019; 322:50-57. [PMID: 31028770 DOI: 10.1016/j.jneumeth.2019.04.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/21/2019] [Accepted: 04/23/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Zebrafish (Danio rerio) are growing in popularity as a vertebrate model organism for the study of spinal neurocircuitry and locomotion. While many studies have used the zebrafish model system for electrophysiological analyses in embryonic and larval stages, there is a growing interest in studying spinal circuits and neurons from adult fish. NEW METHOD To expand upon the existing toolset available to the zebrafish research community, we have developed the first primary cell culture system of adult zebrafish spinal neurons. The intact spinal cord is dissected, and neurons are isolated through enzymatic digestion and mechanical dissociation. Identifiable neurons are viable for electrophysiological analyses after two days in culture. RESULTS Spinal neurons in culture were confirmed by immunofluorescence labeling and found to exhibit distinct morphologies from other cell types, allowing neurons to be identified based on morphology alone. Neurons were suitable for calcium imaging and whole cell patch clamp recordings, which revealed excitable cells with voltage-gated whole cell currents, including tetrodotoxin-sensitive sodium currents. COMPARISON WITH EXISTING METHODS This primary cell culture system is the only methodology available to isolate neurons from the adult zebrafish spinal cord. Other methods rely on keeping the spinal cord intact or the utilization of embryonic or larval stage fish. This method provides a robust platform for use in neurophysiological and pharmacological studies. CONCLUSIONS The novel primary cell culture system described here provides the first in vitro methodology available to isolate and culture neurons from the adult zebrafish spinal cord for use in electrophysiological analyses.
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Affiliation(s)
- Max E Meade
- Occidental College, Department of Biology, 1600 Campus Road, Los Angeles, California, 90041, United States.
| | - Jessica E Roginsky
- Occidental College, Department of Biology, 1600 Campus Road, Los Angeles, California, 90041, United States.
| | - Joseph R Schulz
- Occidental College, Department of Biology, 1600 Campus Road, Los Angeles, California, 90041, United States.
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9
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Impaired Liver Size and Compromised Neurobehavioral Activity are Elicited by Chitosan Nanoparticles in the Zebrafish Embryo Model. NANOMATERIALS 2019; 9:nano9010122. [PMID: 30669437 PMCID: PMC6359003 DOI: 10.3390/nano9010122] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/08/2019] [Accepted: 01/15/2019] [Indexed: 01/31/2023]
Abstract
The use of chitosan nanoparticles (ChNPs) in various biological and environmental applications is attracting great interest. However, potential side effects related to ChNP toxicity remain the major limitation hampering their wide application. For the first time, we investigate the potential organ-specific (cardiac, hepatic, and neuromuscular) toxicity of ChNPs (size 100–150 nm) using the zebrafish embryo model. Our data highlight the absence of both acute and teratogenic toxic effects of ChNPs (~100% survival rate) even at the higher concentration employed (200 mg/L). Although no single sign of cardiotoxicity was observed upon exposure to 200 mg/L of ChNPs, as judged by heartbeat rate, the corrected QT interval (QTc, which measures the time between the start of the Q wave and the end of the T wave in the heart's electrical cycle), maximum cardiac arrest, and ejection fraction assays, the same dosage elicited the impairment of both liver size (decreased liver size, but without steatosis and lipid yolk retention) and neurobehavioral activity (increased movement under different light conditions). Although the observed toxic effect failed to affect embryo survival, whether a prolonged ChNP treatment may induce other potentially harmful effects remains to be elucidated. By reporting new insights on their organ-specific toxicity, our results add novel and useful information into the available data concerning the in vivo effect of ChNPs.
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10
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Boije H, Kullander K. Origin and circuitry of spinal locomotor interneurons generating different speeds. Curr Opin Neurobiol 2018; 53:16-21. [PMID: 29733915 DOI: 10.1016/j.conb.2018.04.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 10/17/2022]
Abstract
The spinal circuitry governing the undulatory movements of swimming vertebrates consist of excitatory and commissural inhibitory interneurons and motor neurons. This locomotor network generates the rhythmic output, coordinate left/right alternation, and permit communication across segments. Through evolution, more complex movement patterns have emerged, made possible by sub-specialization of neural populations within the spinal cord. Walking tetrapods use a similar basic circuitry, but have added layers of complexity for the coordination of intralimbic flexor and extensor muscles as well as interlimbic coordination between the body halves and fore/hindlimbs. Although the basics of these circuits are known there is a gap in our knowledge regarding how different speeds and gaits are coordinated. Analysing subpopulations among described neuronal populations may bring insight into how changes in locomotor output are orchestrated by a hard-wired network.
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Affiliation(s)
- Henrik Boije
- Department of Neuroscience, Uppsala University, Box 593, 751 24 Uppsala, Sweden.
| | - Klas Kullander
- Department of Neuroscience, Uppsala University, Box 593, 751 24 Uppsala, Sweden.
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11
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You X, Sun M, Li J, Bian C, Chen J, Yi Y, Yu H, Shi Q. Mudskippers and Their Genetic Adaptations to an Amphibious Lifestyle. Animals (Basel) 2018; 8:E24. [PMID: 29414871 PMCID: PMC5836032 DOI: 10.3390/ani8020024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 01/25/2018] [Accepted: 02/03/2018] [Indexed: 02/07/2023] Open
Abstract
Mudskippers are the largest group of amphibious teleost fish that are uniquely adapted to live on mudflats. During their successful transition from aqueous life to terrestrial living, these fish have evolved morphological and physiological modifications of aerial vision and olfaction, higher ammonia tolerance, aerial respiration, improved immunological defense against terrestrial pathogens, and terrestrial locomotion using protruded pectoral fins. Comparative genomic and transcriptomic data have been accumulated and analyzed for understanding molecular mechanisms of the terrestrial adaptations. Our current review provides a general introduction to mudskippers and recent research advances of their genetic adaptations to the amphibious lifestyle, which will be helpful for understanding the evolutionary transition of vertebrates from water to land. Our insights into the genomes and transcriptomes will also support molecular breeding, functional identification, and natural compound screening.
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Affiliation(s)
- Xinxin You
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518063, China.
| | - Min Sun
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Jia Li
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Chao Bian
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518063, China.
| | - Jieming Chen
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI-Zhenjiang Institute of Hydrobiology, BGI Marine, BGI, Zhenjiang 212000, China.
| | - Yunhai Yi
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518063, China.
| | - Hui Yu
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
| | - Qiong Shi
- Shenzhen Key Lab of Marine Genomics, Guangdong Provincial Key Lab of Molecular Breeding in Marine Economic Animals, BGI Academy of Marine Sciences, BGI Marine, BGI, Shenzhen 518083, China.
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen 518063, China.
- Laboratory of Aquatic Genomics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China.
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12
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Ziskind-Conhaim L, Hochman S. Diversity of molecularly defined spinal interneurons engaged in mammalian locomotor pattern generation. J Neurophysiol 2017; 118:2956-2974. [PMID: 28855288 DOI: 10.1152/jn.00322.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 01/18/2023] Open
Abstract
Mapping the expression of transcription factors in the mouse spinal cord has identified ten progenitor domains, four of which are cardinal classes of molecularly defined, ventrally located interneurons that are integrated in the locomotor circuitry. This review focuses on the properties of these interneuronal populations and their contribution to hindlimb locomotor central pattern generation. Interneuronal populations are categorized based on their excitatory or inhibitory functions and their axonal projections as predictors of their role in locomotor rhythm generation and coordination. The synaptic connectivity and functions of these interneurons in the locomotor central pattern generators (CPGs) have been assessed by correlating their activity patterns with motor output responses to rhythmogenic neurochemicals and sensory and descending fibers stimulations as well as analyzing kinematic gait patterns in adult mice. The observed complex organization of interneurons in the locomotor CPG circuitry, some with seemingly similar physiological functions, reflects the intricate repertoire associated with mammalian motor control and is consistent with high transcriptional heterogeneity arising from cardinal interneuronal classes. This review discusses insights derived from recent studies to describe innovative approaches and limitations in experimental model systems and to identify missing links in current investigational enterprise.
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Affiliation(s)
- Lea Ziskind-Conhaim
- Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin; and
| | - Shawn Hochman
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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13
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Hao ZZ, Berkowitz A. Shared Components of Rhythm Generation for Locomotion and Scratching Exist Prior to Motoneurons. Front Neural Circuits 2017; 11:54. [PMID: 28848402 PMCID: PMC5554521 DOI: 10.3389/fncir.2017.00054] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/26/2017] [Indexed: 11/13/2022] Open
Abstract
Does the spinal cord use a single network to generate locomotor and scratching rhythms or two separate networks? Previous research showed that simultaneous swim and scratch stimulation (“dual stimulation”) in immobilized, spinal turtles evokes a single rhythm in hindlimb motor nerves with a frequency often greater than during swim stimulation alone or scratch stimulation alone. This suggests that the signals that trigger swimming and scratching converge and are integrated within the spinal cord. However, these results could not determine whether the integration occurs in motoneurons themselves or earlier, in spinal interneurons. Here, we recorded intracellularly from hindlimb motoneurons during dual stimulation. Motoneuron membrane potentials displayed regular oscillations at a higher frequency during dual stimulation than during swim or scratch stimulation alone. In contrast, arithmetic addition of the oscillations during swimming alone and scratching alone with various delays always generated irregular oscillations. Also, the standard deviation of the phase-normalized membrane potential during dual stimulation was similar to those during swimming or scratching alone. In contrast, the standard deviation was greater when pooling cycles of swimming alone and scratching alone for two of the three forms of scratching. This shows that dual stimulation generates a single rhythm prior to motoneurons. Thus, either swimming and scratching largely share a rhythm generator or the two rhythms are integrated into one rhythm by strong interactions among interneurons.
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Affiliation(s)
- Zhao-Zhe Hao
- Department of Biology, University of Oklahoma, NormanOK, United States.,Cellular and Behavioral Neurobiology Graduate Program, University of Oklahoma, NormanOK, United States
| | - Ari Berkowitz
- Department of Biology, University of Oklahoma, NormanOK, United States.,Cellular and Behavioral Neurobiology Graduate Program, University of Oklahoma, NormanOK, United States
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14
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Affiliation(s)
- Michael B. Orger
- Champalimaud Research, Champalimaud Foundation, 1400-038 Lisbon, Portugal;,
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15
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Spinal Hb9::Cre-derived excitatory interneurons contribute to rhythm generation in the mouse. Sci Rep 2017; 7:41369. [PMID: 28128321 PMCID: PMC5269678 DOI: 10.1038/srep41369] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 12/20/2016] [Indexed: 11/14/2022] Open
Abstract
Rhythm generating neurons are thought to be ipsilaterally-projecting excitatory neurons in the thoracolumbar mammalian spinal cord. Recently, a subset of Shox2 interneurons (Shox2 non-V2a INs) was found to fulfill these criteria and make up a fraction of the rhythm-generating population. Here we use Hb9::Cre mice to genetically manipulate Hb9::Cre-derived excitatory interneurons (INs) in order to determine the role of these INs in rhythm generation. We demonstrate that this line captures a consistent population of spinal INs which is mixed with respect to neurotransmitter phenotype and progenitor domain, but does not overlap with the Shox2 non-V2a population. We also show that Hb9::Cre-derived INs include the comparatively small medial population of INs which continues to express Hb9 postnatally. When excitatory neurotransmission is selectively blocked by deleting Vglut2 from Hb9::Cre-derived INs, there is no difference in left-right and/or flexor-extensor phasing between these cords and controls, suggesting that excitatory Hb9::Cre-derived INs do not affect pattern generation. In contrast, the frequencies of locomotor activity are significantly lower in cords from Hb9::Cre-Vglut2Δ/Δ mice than in cords from controls. Collectively, our findings indicate that excitatory Hb9::Cre-derived INs constitute a distinct population of neurons that participates in the rhythm generating kernel for spinal locomotion.
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16
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Czopka T. Insights into mechanisms of central nervous system myelination using zebrafish. Glia 2015; 64:333-49. [PMID: 26250418 DOI: 10.1002/glia.22897] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/14/2015] [Accepted: 07/15/2015] [Indexed: 12/12/2022]
Abstract
Myelin is the multi-layered membrane that surrounds most axons and is produced by oligodendrocytes in the central nervous system (CNS). In addition to its important role in enabling rapid nerve conduction, it has become clear in recent years that myelin plays additional vital roles in CNS function. Myelinating oligodendrocytes provide metabolic support to axons and active myelination is even involved in regulating forms of learning and memory formation. However, there are still large gaps in our understanding of how myelination by oligodendrocytes is regulated. The small tropical zebrafish has become an increasingly popular model organism to investigate many aspects of nervous system formation, function, and regeneration. This is mainly due to two approaches for which the zebrafish is an ideally suited vertebrate model--(1) in vivo live cell imaging using vital dyes and genetically encoded reporters, and (2) gene and target discovery using unbiased screens. This review summarizes how the use of zebrafish has helped understand mechanisms of oligodendrocyte behavior and myelination in vivo and discusses the potential use of zebrafish to shed light on important future questions relating to myelination in the context of CNS development, function and repair.
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Affiliation(s)
- Tim Czopka
- Institute of Neuronal Cell Biology, Technische Universität München, Munich, Germany
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17
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18
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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: 12] [Impact Index Per Article: 1.2] [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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Sorribes A, Þorsteinsson H, Arnardóttir H, Jóhannesdóttir IÞ, Sigurgeirsson B, de Polavieja GG, Karlsson KÆ. The ontogeny of sleep-wake cycles in zebrafish: a comparison to humans. Front Neural Circuits 2013; 7:178. [PMID: 24312015 PMCID: PMC3826060 DOI: 10.3389/fncir.2013.00178] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 10/19/2013] [Indexed: 12/23/2022] Open
Abstract
Zebrafish (Danio rerio) are used extensively in sleep research; both to further understanding of sleep in general and also as a model of human sleep. To date, sleep studies have been performed in larval and adult zebrafish but no efforts have been made to document the ontogeny of zebrafish sleep-wake cycles. Because sleep differs across phylogeny and ontogeny it is important to validate the use of zebrafish in elucidating the neural substrates of sleep. Here we describe the development of sleep and wake across the zebrafish lifespan and how it compares to humans. We find power-law distributions to best fit wake bout data but demonstrate that exponential distributions, previously used to describe sleep bout distributions, fail to adequately account for the data in either species. Regardless, the data reveal remarkable similarities in the ontogeny of sleep cycles in zebrafish and humans. Moreover, as seen in other organisms, zebrafish sleep levels are highest early in ontogeny and sleep and wake bouts gradually consolidate to form the adult sleep pattern. Finally, sleep percentage, bout duration, bout number, and sleep fragmentation are shown to allow for meaningful comparisons between zebrafish and human sleep.
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Affiliation(s)
- Amanda Sorribes
- Instituto Cajal, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - Haraldur Þorsteinsson
- Biomedical Engineering, School of Science and Engineering, Reykjavik UniversityReykjavik, Iceland
- 3Z PharmaceuticalsReykjavik, Iceland
| | - Hrönn Arnardóttir
- Biomedical Engineering, School of Science and Engineering, Reykjavik UniversityReykjavik, Iceland
| | | | - Benjamín Sigurgeirsson
- Biomedical Engineering, School of Science and Engineering, Reykjavik UniversityReykjavik, Iceland
| | | | - Karl Æ. Karlsson
- Biomedical Engineering, School of Science and Engineering, Reykjavik UniversityReykjavik, Iceland
- 3Z PharmaceuticalsReykjavik, Iceland
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20
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Renninger SL, Orger MB. Two-photon imaging of neural population activity in zebrafish. Methods 2013; 62:255-67. [PMID: 23727462 DOI: 10.1016/j.ymeth.2013.05.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 05/21/2013] [Accepted: 05/22/2013] [Indexed: 02/08/2023] Open
Abstract
Rapidly developing imaging technologies including two-photon microscopy and genetically encoded calcium indicators have opened up new possibilities for recording neural population activity in awake, behaving animals. In the small, transparent zebrafish, it is even becoming possible to image the entire brain of a behaving animal with single-cell resolution, creating brain-wide functional maps. In this chapter, we comprehensively review past functional imaging studies in zebrafish, and the insights that they provide into the functional organization of neural circuits. We further offer a basic primer on state-of-the-art methods for in vivo calcium imaging in the zebrafish, including building a low-cost two-photon microscope and highlight possible challenges and technical considerations.
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Affiliation(s)
- Sabine L Renninger
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Avenida Brasília, Doca de Pedrouços, Lisbon, Portugal
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21
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Patterson BW, Abraham AO, MacIver MA, McLean DL. Visually guided gradation of prey capture movements in larval zebrafish. ACTA ACUST UNITED AC 2013; 216:3071-83. [PMID: 23619412 DOI: 10.1242/jeb.087742] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A mechanistic understanding of goal-directed behavior in vertebrates is hindered by the relative inaccessibility and size of their nervous systems. Here, we have studied the kinematics of prey capture behavior in a highly accessible vertebrate model organism, the transparent larval zebrafish (Danio rerio), to assess whether they use visual cues to systematically adjust their movements. We found that zebrafish larvae scale the speed and magnitude of turning movements according to the azimuth of one of their standard prey, paramecia. They also bias the direction of subsequent swimming movements based on prey azimuth and select forward or backward movements based on the prey's direction of travel. Once within striking distance, larvae generate either ram or suction capture behaviors depending on their distance from the prey. From our experimental estimations of ocular receptive fields, we ascertained that the ultimate decision to consume prey is likely a function of the progressive vergence of the eyes that places the target in a proximal binocular 'capture zone'. By repeating these experiments in the dark, we demonstrate that paramecia are only consumed if they contact the anterior extremities of larvae, which triggers ocular vergence and tail movements similar to close proximity captures in lit conditions. These observations confirm the importance of vision in the graded movements we observe leading up to capture of more distant prey in the light, and implicate somatosensation in captures in the absence of light. We discuss the implications of these findings for future work on the neural control of visually guided behavior in zebrafish.
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Affiliation(s)
- Bradley W Patterson
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA
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22
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Arrenberg AB, Driever W. Integrating anatomy and function for zebrafish circuit analysis. Front Neural Circuits 2013; 7:74. [PMID: 23630469 PMCID: PMC3632786 DOI: 10.3389/fncir.2013.00074] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/03/2013] [Indexed: 01/31/2023] Open
Abstract
Due to its transparency, virtually every brain structure of the larval zebrafish is accessible to light-based interrogation of circuit function. Advanced stimulation techniques allow the activation of optogenetic actuators at different resolution levels, and genetically encoded calcium indicators report the activity of a large proportion of neurons in the CNS. Large datasets result and need to be analyzed to identify cells that have specific properties—e.g., activity correlation to sensory stimulation or behavior. Advances in three-dimensional (3D) functional mapping in zebrafish are promising; however, the mere coordinates of implicated neurons are not sufficient. To comprehensively understand circuit function, these functional maps need to be placed into the proper context of morphological features and projection patterns, neurotransmitter phenotypes, and key anatomical landmarks. We discuss the prospect of merging functional and anatomical data in an integrated atlas from the perspective of our work on long-range dopaminergic neuromodulation and the oculomotor system. We propose that such a resource would help researchers to surpass current hurdles in circuit analysis to achieve an integrated understanding of anatomy and function.
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Affiliation(s)
- Aristides B Arrenberg
- Developmental Biology, Institute of Biology I, Faculty of Biology, BIOSS - Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg Freiburg, Germany
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23
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Nesan D, Vijayan MM. Role of glucocorticoid in developmental programming: evidence from zebrafish. Gen Comp Endocrinol 2013; 181:35-44. [PMID: 23103788 DOI: 10.1016/j.ygcen.2012.10.006] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 10/13/2012] [Indexed: 10/27/2022]
Abstract
The vertebrate corticosteroid stress response is highly conserved and a key function is to restore homeostasis by mobilizing and reallocating energy stores. This process is primarily initiated by activation of the hypothalamus-pituitary-adrenal axis, leading to the release of corticosteroids into the circulation. In teleosts, cortisol is the primary corticosteroid that is released into the circulation in response to stress. This steroid activates corticosteroid receptors that are ligand-bound transcription factors, modulating downstream gene expression in target tissues. Recent research in zebrafish (Danio rerio) has identified novel roles for cortisol in early developmental processes, including organogenesis and mesoderm formation. As cortisol biosynthesis commences only around the time of hatch in teleosts, the early developmental events are orchestrated by cortisol that is maternally deposited prior to fertilization. This review will highlight the molecular events leading to the development of the corticosteroid stress axis, and the possible role of cortisol in the developmental programming of stress axis function. Use of zebrafish as a model may lead to significant insights into the conserved role of glucocorticoids during early development with potential implications in biomedical research, including fetal stress syndromes in humans.
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Affiliation(s)
- Dinushan Nesan
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
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24
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Abstract
During waking behavior, animals adapt their state of arousal in response to environmental pressures. Sensory processing is regulated in aroused states, and several lines of evidence imply that this is mediated at least partly by the serotonergic system. However, there is little information directly showing that serotonergic function is required for state-dependent modulation of sensory processing. Here we find that zebrafish larvae can maintain a short-term state of arousal during which neurons in the dorsal raphe modulate sensory responsiveness to behaviorally relevant visual cues. After a brief exposure to water flow, larvae show elevated activity and heightened sensitivity to perceived motion. Calcium imaging of neuronal activity after flow revealed increased activity in serotonergic neurons of the dorsal raphe. Genetic ablation of these neurons abolished the increase in visual sensitivity during arousal without affecting baseline visual function or locomotor activity. We traced projections from the dorsal raphe to a major visual area, the optic tectum. Laser ablation of the tectum demonstrated that this structure, like the dorsal raphe, is required for improved visual sensitivity during arousal. These findings reveal that serotonergic neurons of the dorsal raphe have a state-dependent role in matching sensory responsiveness to behavioral context.
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25
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Abstract
Motor behaviour results from information processing across multiple neural networks acting at all levels from initial selection of the behaviour to its final generation. Understanding how motor behaviour is produced requires identifying the constituent neurons of these networks, their cellular properties, and their pattern of synaptic connectivity. Neural networks have been traditionally studied with neurophysiological and neuroanatomical approaches. These approaches have been highly successful in particularly suitable 'model' preparations, typically ones in which the numbers of neurons in the networks were relatively small, neural network composition was unvarying across individual animals, and the preparations continued to produce fictive motor patterns in vitro. However, analysing networks without these characteristics, and analysing the complete ensemble of networks that cooperatively generate behaviours, is difficult with these approaches. Recently developed molecular and neurogenetic tools provide additional avenues for analysing motor networks by allowing individual or groups of neurons within networks to be manipulated in novel ways and allowing experiments to be performed not only in vitro but also in vivo. We review here some of the new insights into motor network function that these advances have provided and indicate how these advances might bridge gaps in our understanding of motor control. To these ends, we first review motor neural network organisation highlighting cross-phylum principles. We then use prominent examples from the field to show how neurogenetic approaches can complement classical physiological studies, and identify additional areas where these approaches could be advantageously applied.
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Affiliation(s)
- Ansgar Büschges
- Zoological Institute, Department of Animal Physiology, Biocenter Cologne, University of Cologne, Zülpicher Straße 47b, 50674 Cologne, Germany.
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26
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Abstract
A central goal of modern neuroscience is to obtain a mechanistic understanding of higher brain functions under healthy and diseased conditions. Addressing this challenge requires rigorous experimental and theoretical analysis of neuronal circuits. Recent advances in optogenetics, high-resolution in vivo imaging, and reconstructions of synaptic wiring diagrams have created new opportunities to achieve this goal. To fully harness these methods, model organisms should allow for a combination of genetic and neurophysiological approaches in vivo. Moreover, the brain should be small in terms of neuron numbers and physical size. A promising vertebrate organism is the zebrafish because it is small, it is transparent at larval stages and it offers a wide range of genetic tools and advantages for neurophysiological approaches. Recent studies have highlighted the potential of zebrafish for exhaustive measurements of neuronal activity patterns, for manipulations of defined cell types in vivo and for studies of causal relationships between circuit function and behavior. In this article, we summarize background information on the zebrafish as a model in modern systems neuroscience and discuss recent results.
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Affiliation(s)
- Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstr. 66, CH-4058 Basel, Switzerland.
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27
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Alternative startle motor patterns and behaviors in the larval zebrafish (Danio rerio). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 198:11-24. [DOI: 10.1007/s00359-011-0682-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 09/11/2011] [Accepted: 09/14/2011] [Indexed: 10/17/2022]
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28
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Hunter PR, Nikolaou N, Odermatt B, Williams PR, Drescher U, Meyer MP. Localization of Cadm2a and Cadm3 proteins during development of the zebrafish nervous system. J Comp Neurol 2011; 519:2252-70. [PMID: 21456004 DOI: 10.1002/cne.22627] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Members of the Cadm/SynCAM/Necl/IGSF/TSLC family of cell adhesion molecules are known to have diverse functions during development of the nervous system, but information regarding their role during central nervous system (CNS) development in vivo is scarce. The rapid development of a relatively simple nervous system in larval zebrafish makes them a highly tractable model organism for studying gene function during nervous system development. An essential prerequisite for functional studies is a description of protein localization. To address this we have generated subtype-specific antibodies to two members of the zebrafish cell adhesion molecule family: cadm2a and cadm3. Using these novel antibodies we show that cadm3 and cadm2a are expressed throughout the nervous system of larval stage zebrafish. Particularly striking, and largely nonoverlapping expression of cadm2a and cadm3 is observed in the developing retina and spinal cord. Using in vitro binding assays we show that cadm2a and cadm3 bind heterophilically and preferentially to cadm1 and cadm4, respectively. These binding preferences are very similar to those seen for tetrapod Cadms but our study of protein localization suggests novel and diverse functions of cadms during nervous system development.
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Affiliation(s)
- Paul R Hunter
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK
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29
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Borisyuk R, Al Azad AK, Conte D, Roberts A, Soffe SR. Modeling the connectome of a simple spinal cord. Front Neuroinform 2011; 5:20. [PMID: 21977016 PMCID: PMC3178813 DOI: 10.3389/fninf.2011.00020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 08/29/2011] [Indexed: 11/30/2022] Open
Abstract
In this paper we develop a computational model of the anatomy of a spinal cord. We address a long-standing ambition of neuroscience to understand the structure–function problem by modeling the complete spinal cord connectome map in the 2-day old hatchling Xenopus tadpole. Our approach to modeling neuronal connectivity is based on developmental processes of axon growth. A simple mathematical model of axon growth allows us to reconstruct a biologically realistic connectome of the tadpole spinal cord based on neurobiological data. In our model we distribute neuron cell bodies and dendrites on both sides of the body based on experimental measurements. If growing axons cross the dendrite of another neuron, they make a synaptic contact with a defined probability. The total neuronal network contains ∼1,500 neurons of six cell-types with a total of ∼120,000 connections. The anatomical model contains random components so each repetition of the connectome reconstruction procedure generates a different neuronal network, though all share consistent features such as distributions of cell bodies, dendrites, and axon lengths. Our study reveals a complex structure for the connectome with many interesting specific features including contrasting distributions of connection length distributions. The connectome also shows some similarities to connectivity graphs for other animals such as the global neuronal network of C. elegans. In addition to the interesting intrinsic properties of the connectome, we expect the ability to grow and analyze a biologically realistic spinal cord connectome will provide valuable insights into the properties of the real neuronal networks underlying simple behavior.
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Affiliation(s)
- Roman Borisyuk
- School of Computing and Mathematics, University of Plymouth Plymouth, UK
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30
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Taniguchi H, He M, Wu P, Kim S, Paik R, Sugino K, Kvitsiani D, Kvitsani D, Fu Y, Lu J, Lin Y, Miyoshi G, Shima Y, Fishell G, Nelson SB, Huang ZJ. A resource of Cre driver lines for genetic targeting of GABAergic neurons in cerebral cortex. Neuron 2011; 71:995-1013. [PMID: 21943598 PMCID: PMC3779648 DOI: 10.1016/j.neuron.2011.07.026] [Citation(s) in RCA: 1330] [Impact Index Per Article: 102.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2011] [Indexed: 10/17/2022]
Abstract
A key obstacle to understanding neural circuits in the cerebral cortex is that of unraveling the diversity of GABAergic interneurons. This diversity poses general questions for neural circuit analysis: how are these interneuron cell types generated and assembled into stereotyped local circuits and how do they differentially contribute to circuit operations that underlie cortical functions ranging from perception to cognition? Using genetic engineering in mice, we have generated and characterized approximately 20 Cre and inducible CreER knockin driver lines that reliably target major classes and lineages of GABAergic neurons. More select populations are captured by intersection of Cre and Flp drivers. Genetic targeting allows reliable identification, monitoring, and manipulation of cortical GABAergic neurons, thereby enabling a systematic and comprehensive analysis from cell fate specification, migration, and connectivity, to their functions in network dynamics and behavior. As such, this approach will accelerate the study of GABAergic circuits throughout the mammalian brain.
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Affiliation(s)
- Hiroki Taniguchi
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
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31
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Yanik MF, Rohde CB, Pardo-Martin C. Technologies for Micromanipulating, Imaging, and Phenotyping Small Invertebrates and Vertebrates. Annu Rev Biomed Eng 2011; 13:185-217. [DOI: 10.1146/annurev-bioeng-071910-124703] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mehmet Fatih Yanik
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Christopher B. Rohde
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Carlos Pardo-Martin
- Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139;
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
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32
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Spinocerebellar ataxia type 13 mutant potassium channel alters neuronal excitability and causes locomotor deficits in zebrafish. J Neurosci 2011; 31:6831-41. [PMID: 21543613 DOI: 10.1523/jneurosci.6572-10.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Whether changes in neuronal excitability can cause neurodegenerative disease in the absence of other factors such as protein aggregation is unknown. Mutations in the Kv3.3 voltage-gated K(+) channel cause spinocerebellar ataxia type 13 (SCA13), a human autosomal-dominant disease characterized by locomotor impairment and the death of cerebellar neurons. Kv3.3 channels facilitate repetitive, high-frequency firing of action potentials, suggesting that pathogenesis in SCA13 is triggered by changes in electrical activity in neurons. To investigate whether SCA13 mutations alter excitability in vivo, we expressed the human dominant-negative R420H mutant subunit in zebrafish. The disease-causing mutation specifically suppressed the excitability of Kv3.3-expressing, fast-spiking motor neurons during evoked firing and fictive swimming and, in parallel, decreased the precision and amplitude of the startle response. The dominant-negative effect of the mutant subunit on K(+) current amplitude was directly responsible for the reduced excitability and locomotor phenotype. Our data provide strong evidence that changes in excitability initiate pathogenesis in SCA13 and establish zebrafish as an excellent model system for investigating how changes in neuronal activity impair locomotor control and cause cell death.
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Smith J, Morgan JR, Zottoli SJ, Smith PJ, Buxbaum JD, Bloom OE. Regeneration in the era of functional genomics and gene network analysis. THE BIOLOGICAL BULLETIN 2011; 221:18-34. [PMID: 21876108 PMCID: PMC4109899 DOI: 10.1086/bblv221n1p18] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
What gives an organism the ability to regrow tissues and to recover function where another organism fails is the central problem of regenerative biology. The challenge is to describe the mechanisms of regeneration at the molecular level, delivering detailed insights into the many components that are cross-regulated. In other words, a broad, yet deep dissection of the system-wide network of molecular interactions is needed. Functional genomics has been used to elucidate gene regulatory networks (GRNs) in developing tissues, which, like regeneration, are complex systems. Therefore, we reason that the GRN approach, aided by next generation technologies, can also be applied to study the molecular mechanisms underlying the complex functions of regeneration. We ask what characteristics a model system must have to support a GRN analysis. Our discussion focuses on regeneration in the central nervous system, where loss of function has particularly devastating consequences for an organism. We examine a cohort of cells conserved across all vertebrates, the reticulospinal (RS) neurons, which lend themselves well to experimental manipulations. In the lamprey, a jawless vertebrate, there are giant RS neurons whose large size and ability to regenerate make them particularly suited for a GRN analysis. Adding to their value, a distinct subset of lamprey RS neurons reproducibly fail to regenerate, presenting an opportunity for side-by-side comparison of gene networks that promote or inhibit regeneration. Thus, determining the GRN for regeneration in RS neurons will provide a mechanistic understanding of the fundamental cues that lead to success or failure to regenerate.
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Affiliation(s)
- Joel Smith
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering and The Josephine Bay Pau Center for Comparative Molecular Biology and Evolution, The Marine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts 02543
- Co-corresponding authors: and obloom@ nshs.edu
| | - Jennifer R. Morgan
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Steven J. Zottoli
- Department of Biology, 59 Lab Campus Drive, Williams College, Williamstown, Massachusetts 01267 and Cellular Dynamics Program, The Marine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts 02453
| | - Peter J. Smith
- The Biocurrents Research Center, Cellular Dynamics Program, The Marine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts 02543
| | - Joseph D. Buxbaum
- Department of Psychiatry and the Friedman Brain Institute, Mount Sinai School of Medicine, One Gustave L Levy Plc, Box 1668, New York, New York 10029
| | - Ona E. Bloom
- The Center for Autoimmune and Musculoskeletal Disease, The Feinstein Institute for Medical Research, 350 Community Drive, Manhasset, New York 11030
- Co-corresponding authors: and obloom@ nshs.edu
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34
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Wyart C, Del Bene F. Let there be light: zebrafish neurobiology and the optogenetic revolution. Rev Neurosci 2011; 22:121-30. [PMID: 21615266 DOI: 10.1515/rns.2011.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Optogenetics has revolutionized the toolbox arsenal that neuroscientists now possess to investigate neuronal circuit function in intact and living animals. With a combination of light emitting 'sensors' and light activated 'actuators', we can monitor and control neuronal activity with minimal perturbation and unprecedented spatiotemporal resolution. Zebrafish neuronal circuits represent an ideal system to apply an optogenetic based analysis owing to its transparency, relatively small size and amenability to genetic manipulation. In this review, we describe some of the most recent advances in the development and applications of optogenetic sensors (i.e., genetically encoded calcium indicators and voltage sensors) and actuators (i.e., light activated ion channels and ion pumps). We focus mostly on the tools that have already been successfully applied in zebrafish and on those that show the greatest potential for the future. We also describe crucial technical aspects to implement optogenetics in zebrafish including strategies to drive a high level of transgene expression in defined neuronal populations, and recent optical advances that allow the precise spatiotemporal control of sample illumination.
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Affiliation(s)
- Claire Wyart
- Institut du Cerveau et de la Moelle epiniere, Centre de Recherche, CHU Pitié-Salpétrière, Paris, France.
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Abstract
Recent studies have identified the leucine rich repeat protein LRRTM2 as a post-synaptic ligand of Neurexins. Neurexins also bind the post-synaptic adhesion molecules, Neuroligins. All three families of genes have been implicated in the etiologies of neurodevelopmental disorders, specifically autism spectrum disorders and schizophrenia. Does the binding promiscuity of Neurexins now suggest complex cooperativity or redundancy at the synapse? While recent studies in primary neuronal cultures and also systematic extracellular protein interaction screens suggest summative effects of these systems, we propose that studying these interactions in the developing zebrafish embryo or larvae may shed more light on their functions during synaptogenesis in vivo. These gene families have recently been extensively characterized in zebrafish, demonstrating high sequence conservation with the human genes. The simpler circuitry of the zebrafish, together with the characterization of the expression patterns down to single, identifiable neurons and the ability to knock-down or over-express multiple genes in a rapid way lend themselves to dissecting complex interaction pathways. Furthermore, the capability of performing high-throughput drug screens suggests that these small vertebrates may prove extremely useful in identifying pharmacological approaches to treating autism spectrum disorders.
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Affiliation(s)
| | - Philip Washbourne
- Institute of Neuroscience, University of Oregon, Eugene OR 97403, USA
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Rieger S, Wang F, Sagasti A. Time-lapse imaging of neural development: zebrafish lead the way into the fourth dimension. Genesis 2011; 49:534-45. [PMID: 21305690 DOI: 10.1002/dvg.20729] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/24/2011] [Accepted: 01/25/2011] [Indexed: 01/01/2023]
Abstract
Time-lapse imaging is often the only way to appreciate fully the many dynamic cell movements critical to neural development. Zebrafish possess many advantages that make them the best vertebrate model organism for live imaging of dynamic development events. This review will discuss technical considerations of time-lapse imaging experiments in zebrafish, describe selected examples of imaging studies in zebrafish that revealed new features or principles of neural development, and consider the promise and challenges of future time-lapse studies of neural development in zebrafish embryos and adults.
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Affiliation(s)
- Sandra Rieger
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, California, USA
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Beyond connectivity of locomotor circuitry-ionic and modulatory mechanisms. PROGRESS IN BRAIN RESEARCH 2011; 187:99-110. [PMID: 21111203 DOI: 10.1016/b978-0-444-53613-6.00007-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Discrete neural networks in the central nervous system generate the repertoire of motor behavior necessary for animal survival. The final motor output of these networks is the result of the anatomical connectivity between the individual neurons and also their biophysical properties as well as the dynamics of their synaptic transmission. To illustrate how this processing takes place to produce coordinated motor activity, we have summarized some of the results available from the lamprey spinal locomotor network. The detailed knowledge available in this model system on the organization of the network together with the properties of the constituent neurons and the modulatory systems allows us to determine how the impact of specific ion channels and receptors is translated to the global activity of the locomotor circuitry. Understanding the logic of the neuronal and synaptic processing within the locomotor network will provide information about not only their normal operation but also how they react to disruption such as injuries or trauma.
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Abstract
Nitric oxide (NO) is a signaling molecule that is synthesized in a range of tissues by the NO synthases (NOSs). In the immature nervous system, the neuronal isoform of NOS (NOS1) is often expressed during periods of axon outgrowth and elaboration. However, there is little direct molecular evidence to suggest that NOS1 influences these processes. Here we address the functional role of NOS1 during in vivo zebrafish locomotor circuit development. We show that NOS1 is expressed in a population of interneurons that lie close to nascent motoneurons of the spinal cord. To determine how this protein regulates spinal network assembly, we perturbed NOS1 expression in vivo with antisense morpholino oligonucleotides. This treatment dramatically increased the number of axon collaterals formed by motoneuron axons, an effect mimicked by pharmacological inhibition of the NO/cGMP signaling pathway. In contrast, exogenous elevation of NO/cGMP levels suppressed motor axon branching. These effects were not accompanied by a change in motoneuron number, suggesting that NOS1 does not regulate motoneuron differentiation. Finally we show that perturbation of NO signaling affects the ontogeny of locomotor performance. Our findings provide evidence that NOS1 is a key regulator of motor axon ontogeny in the developing vertebrate spinal cord.
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Abstract
While the research community has accepted the value of rodent models as informative research platforms, there is less awareness of the utility of other small vertebrate and invertebrate animal models. Neuroscience is increasingly turning to smaller, non-rodent models to understand mechanisms related to neuropsychiatric disorders. Although they can never replace clinical research, there is much to be learnt from 'small brains'. In particular, these species can offer flexible genetic 'tool kits' that can be used to explore the expression and function of candidate genes in different brain regions. Very small animals also offer efficiencies with respect to high-throughput screening programs. This review provides a concise overview of the utility of models based on worm, fruit fly, honeybee and zebrafish. Although these species may have small brains, they offer the neuropsychiatric research community opportunities to explore some of the most important research questions in our field.
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Whelan PJ. Shining light into the black box of spinal locomotor networks. Philos Trans R Soc Lond B Biol Sci 2010; 365:2383-95. [PMID: 20603359 DOI: 10.1098/rstb.2009.0322] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rhythmic activity is responsible for numerous essential motor functions including locomotion, breathing and chewing. In the case of locomotion, it has been realized for some time that the spinal cord contains sufficient circuitry to produce a sophisticated stepping pattern. However, the central pattern generator for locomotion in mammals has remained a 'black box' where inputs to the network were manipulated and the outputs interpreted. Over the last decade, new genetic approaches and techniques have been developed that provide ways to identify and manipulate the activity of classes of interneurons. The use of these techniques will be critically discussed and related to current models of network function.
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Affiliation(s)
- Patrick J Whelan
- Department of Comparative Biology and Experimental Medicine, Hotchkiss Brain Institute, HS 2119, University of Calgary, Calgary, Alberta, Canada.
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Bai Q, Burton EA. Zebrafish models of Tauopathy. Biochim Biophys Acta Mol Basis Dis 2010; 1812:353-63. [PMID: 20849952 DOI: 10.1016/j.bbadis.2010.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 09/08/2010] [Indexed: 01/06/2023]
Abstract
Tauopathies are a group of incurable neurodegenerative diseases, in which loss of neurons is accompanied by intracellular deposition of fibrillar material composed of hyperphosphorylated forms of the microtubule-associated protein Tau. A zebrafish model of Tauopathy could complement existing murine models by providing a platform for genetic and chemical screens, in order to identify novel therapeutic targets and compounds with disease-modifying potential. In addition, Tauopathy zebrafish would be useful for hypothesis-driven experiments, especially those exploiting the potential to deploy in vivo imaging modalities. Several considerations, including conservation of specialized neuronal and other cellular populations, and biochemical pathways implicated in disease pathogenesis, suggest that the zebrafish brain is an appropriate setting in which to model these complex disorders. Novel transgenic zebrafish lines expressing wild-type and mutant forms of human Tau in CNS neurons have recently been reported. These studies show evidence that human Tau undergoes disease-relevant changes in zebrafish neurons, including somato-dendritic relocalization, hyperphosphorylation and aggregation. In addition, preliminary evidence suggests that Tau transgene expression can precipitate neuronal dysfunction and death. These initial studies are encouraging that the zebrafish holds considerable promise as a model in which to study Tauopathies. Further studies are necessary to clarify the phenotypes of transgenic lines and to develop assays and models suitable for unbiased high-throughput screening approaches. This article is part of a Special Issue entitled Zebrafish Models of Neurological Diseases.
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Affiliation(s)
- Qing Bai
- Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh School of Medicine, PA, USA
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Fetcho JR, McLean DL. Some principles of organization of spinal neurons underlying locomotion in zebrafish and their implications. Ann N Y Acad Sci 2010; 1198:94-104. [PMID: 20536924 DOI: 10.1111/j.1749-6632.2010.05539.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent studies of the spinal motor system of zebrafish, along with work in other species, are leading to some principles that appear to underlie the organization and recruitment of motor networks in cord: (1) broad neuronal classes defined by a set of transcription factors, key morphological features, and transmitter phenotypes arise in an orderly way from different dorso-ventral zones in spinal cord; (2) motor behaviors and both motoneurons and interneurons differentiate in order from gross, often faster, movements and the neurons driving them to progressively slower movements and their underlying neurons; (3) recruitment order of motoneurons and interneurons is based upon time of differentiation; (4) different locomotor speeds involve some shifts in the set of active interneurons. Here we review these principles and some of their implications for other parts of the brain, other vertebrates, and limbed locomotion.
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Affiliation(s)
- Joseph R Fetcho
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
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Carmean V, Ribera AB. Genetic Analysis of the Touch Response in Zebrafish ( Danio rerio). INTERNATIONAL JOURNAL OF COMPARATIVE PSYCHOLOGY 2010; 23:91. [PMID: 26456999 PMCID: PMC4596712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023] Open
Abstract
Both mammals and zebrafish possess mechanosensory neurons that detect tactile sensation via free nerve endings. However, the basis for mechanotransduction and the unique cellular properties of these sensory neurons are poorly understood. We review the advantages of zebrafish for studies of the biological mechanisms involved in touch sensitivity. Importantly, Granato and colleagues (1996) demonstrated that a simple touch assay efficiently recovers mutations that affect sensory neurons.
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Ryczko D, Dubuc R, Cabelguen JM. Rhythmogenesis in axial locomotor networks: an interspecies comparison. PROGRESS IN BRAIN RESEARCH 2010; 187:189-211. [PMID: 21111209 DOI: 10.1016/b978-0-444-53613-6.00013-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During locomotion, specialized neural networks referred to as "central pattern generators" ensure precise temporal relations between the axial segments, both in limbed and limbless vertebrates. These neural networks are intrinsically capable of generating coordinated patterns of rhythmic activity in the absence of sensory feedback or descending command from higher brain centers. Rhythmogenesis in these neural circuits lies on several mechanisms, both at the cellular and the network levels. In this chapter, we compare the anatomical organization of the axial networks, the role of identified spinal neurons, and their interactions in rhythmogenesis in four species: lamprey, zebrafish, Xenopus tadpole, and salamander. The comparison suggests that several principles in axial network design are phylogenetically conserved among vertebrates.
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Affiliation(s)
- Dimitri Ryczko
- Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, Montréal, Québec, Canada
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Abstract
The nervous system can generate rhythms of various frequencies; on the low-frequency side, we have the circuits regulating circadian rhythms with a 24-h period, while on the high-frequency side we have the motor circuits that underlie flight in a hummingbird. Given the ubiquitous nature of rhythms, it is surprising that we know very little of the cellular and molecular mechanisms that produce them in the embryos and of their potential role during the development of neuronal circuits. Recently, zebrafish has been developed as a vertebrate model to study the genetics of neural development. Zebrafish offer several advantages to the study of nervous system development including optical and electrophysiological analysis of neuronal activity even at the earliest embryonic stages. This unique combination of physiology and genetics in the same animal model has led to insights into the development of neuronal networks. This chapter reviews work on the development of zebrafish motor rhythms and speculates on birth and maturation of the circuits that produce them.
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Ganser LR, Dallman JE. Glycinergic synapse development, plasticity, and homeostasis in zebrafish. Front Mol Neurosci 2009; 2:30. [PMID: 20126315 PMCID: PMC2815536 DOI: 10.3389/neuro.02.030.2009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 11/26/2009] [Indexed: 11/13/2022] Open
Abstract
The zebrafish glial glycine transporter 1 (GlyT1) mutant provides an animal model in which homeostatic plasticity at glycinergic synapses restores rhythmic motor behaviors. GlyT1 mutants, initially paralyzed by the build-up of the inhibitory neurotransmitter glycine, stage a gradual recovery that is associated with reductions in the strength of evoked glycinergic responses. Gradual motor recovery suggests sequential compensatory mechanisms that culminate in the down-regulation of the neuronal glycine receptor. However, how motor recovery is initiated and how other forms of plasticity contribute to behavioral recovery are still outstanding questions that we discuss in the context of (1) glycinergic synapses as they function in spinal circuits that produce rhythmic motor behaviors, (2) the proteins involved in regulating glycinergic synaptic strength, (3) current models of glycinergic synaptogenesis, and (4) plasticity mechanisms that modulate the strength of glycinergic synapses. Concluding remarks (5) explore the potential for distinct plasticity mechanisms to act in concert at different spatial and temporal scales to achieve a dynamic stability that results in balanced motor behaviors.
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Affiliation(s)
- Lisa R Ganser
- Department of Biology, University of Miami Coral Gables, FL, USA
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Pietri T, Manalo E, Ryan J, Saint-Amant L, Washbourne P. Glutamate drives the touch response through a rostral loop in the spinal cord of zebrafish embryos. Dev Neurobiol 2009; 69:780-95. [PMID: 19634126 DOI: 10.1002/dneu.20741] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Characterizing connectivity in the spinal cord of zebrafish embryos is not only prerequisite to understanding the development of locomotion, but is also necessary for maximizing the potential of genetic studies of circuit formation in this model system. During their first day of development, zebrafish embryos show two simple motor behaviors. First, they coil their trunks spontaneously, and a few hours later they start responding to touch with contralateral coils. These behaviors are contemporaneous until spontaneous coils become infrequent by 30 h. Glutamatergic neurons are distributed throughout the embryonic spinal cord, but their contribution to these early motor behaviors in immature zebrafish is still unclear. We demonstrate that the kinetics of spontaneous coiling and touch-evoked responses show distinct developmental time courses and that the touch response is dependent on AMPA-type glutamate receptor activation. Transection experiments suggest that the circuits required for touch-evoked responses are confined to the spinal cord and that only the most rostral part of the spinal cord is sufficient for triggering the full response. This rostral sensory connection is presumably established via CoPA interneurons, as they project to the rostral spinal cord. Electrophysiological analysis demonstrates that these neurons receive short latency AMPA-type glutamatergic inputs in response to ipsilateral tactile stimuli. We conclude that touch responses in early embryonic zebrafish arise only after glutamatergic synapses connect sensory neurons and interneurons to the contralateral motor network via a rostral loop. This helps define an elementary circuit that is modified by the addition of sensory inputs, resulting in behavioral transformation.
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Affiliation(s)
- Thomas Pietri
- Institute of Neuroscience, University of Oregon, Eugene, Oregon 97403, USA
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Zhu P, Narita Y, Bundschuh ST, Fajardo O, Schärer YPZ, Chattopadhyaya B, Bouldoires EA, Stepien AE, Deisseroth K, Arber S, Sprengel R, Rijli FM, Friedrich RW. Optogenetic Dissection of Neuronal Circuits in Zebrafish using Viral Gene Transfer and the Tet System. Front Neural Circuits 2009; 3:21. [PMID: 20126518 PMCID: PMC2805431 DOI: 10.3389/neuro.04.021.2009] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 11/27/2009] [Indexed: 01/07/2023] Open
Abstract
The conditional expression of transgenes at high levels in sparse and specific populations of neurons is important for high-resolution optogenetic analyses of neuronal circuits. We explored two complementary methods, viral gene delivery and the iTet-Off system, to express transgenes in the brain of zebrafish. High-level gene expression in neurons was achieved by Sindbis and Rabies viruses. The Tet system produced strong and specific gene expression that could be modulated conveniently by doxycycline. Moreover, transgenic lines showed expression in distinct, sparse and stable populations of neurons that appeared to be subsets of the neurons targeted by the promoter driving the Tet-activator. The Tet system therefore provides the opportunity to generate libraries of diverse expression patterns similar to gene trap approaches or the thy-1 promoter in mice, but with the additional possibility to pre-select cell types of interest. In transgenic lines expressing channelrhodopsin-2, action potential firing could be precisely controlled by two-photon stimulation at low laser power, presumably because the expression levels of the Tet-controlled genes were high even in adults. In channelrhodopsin-2-expressing larvae, optical stimulation with a single blue LED evoked distinct swimming behaviors including backward swimming. These approaches provide new opportunities for the optogenetic dissection of neuronal circuit structure and function.
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Affiliation(s)
- Peixin Zhu
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation Basel, Switzerland
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