1
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Kalyviotis K, Pantazis P. Primed conversion: The emerging player of precise and nontoxic photoconversion. J Microsc 2023. [PMID: 37937409 DOI: 10.1111/jmi.13244] [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: 06/30/2023] [Revised: 10/17/2023] [Accepted: 11/02/2023] [Indexed: 11/09/2023]
Abstract
In 2015, we reported primed conversion, a novel way to convert green-to-red photoconvertible fluorescent proteins, which emerges as a powerful tool for precision optical imaging. Primed conversion uses the intercept of blue and red-to-far-red light instead of traditional violet or near-UV light illumination which offers a series of advantages. Here, we review the fundamental principles and applications of primed conversion with a focus on its use in single-cell labelling and lineage tracing. We provide a historical perspective of lineage tracing techniques, thereby covering basic principles of fluorescence, photoconvertible fluorescent proteins, and eventually primed conversion. We then present the molecular requirements for primed conversion to take place and showcase how it can be used for dual-colour high-fidelity lineage tracing. Further, we discuss potential future developments of the primed conversion imaging toolkit that can benefit the study of both development and disease progression.
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2
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Sullivan KG, Bashaw GJ. Intracellular Trafficking Mechanisms that Regulate Repulsive Axon Guidance. Neuroscience 2023; 508:123-136. [PMID: 35863679 PMCID: PMC9839465 DOI: 10.1016/j.neuroscience.2022.07.012] [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: 03/31/2022] [Revised: 07/01/2022] [Accepted: 07/13/2022] [Indexed: 01/17/2023]
Abstract
Friedrich Bonhoeffer made seminal contributions to the study of axon guidance in the developing nervous system. His discoveries of key cellular and molecular mechanisms that dictate wiring specificity laid the foundation for countless investigators who have followed in his footsteps. Perhaps his most significant contribution was the cloning and characterization of members of the conserved ephrin family of repulsive axon guidance cues. In this review, we highlight the major contributions that Bonhoeffer and his colleagues made to the field of axon guidance, and discuss ongoing investigations into the diverse array of mechanisms that ensure that axon repulsion is precisely regulated to allow for accurate pathfinding. Specifically, we focus our discussion on the post-translational regulation of two major families of repulsive axon guidance factors: ephrin ligands and their Eph receptors, and slit ligands and their Roundabout (Robo) receptors. We will give special emphasis to the ways in which regulated endocytic trafficking events allow navigating axons to adjust their responses to repellant signals and how these trafficking events are intimately related to receptor signaling. By highlighting parallels and differences between the regulation of these two important repulsive axon guidance pathways, we hope to identify key outstanding questions for future investigation.
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Affiliation(s)
- Kelly G Sullivan
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States
| | - Greg J Bashaw
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, United States.
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3
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Ros O, Nicol X. Axon pathfinding and targeting: (R)evolution of insights from in vitro assays. Neuroscience 2023; 508:110-122. [PMID: 36096337 DOI: 10.1016/j.neuroscience.2022.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/01/2022] [Accepted: 09/05/2022] [Indexed: 01/17/2023]
Abstract
Investigating axonal behaviors while neurons are connecting with each other has been a challenge since the early studies on nervous system development. While molecule-driven axon pathfinding has been theorized by observing neurons at different developmental stages in vivo, direct observation and measurements of axon guidance behaviors required the invention of in vitro systems enabling to test the impact of molecules or cellular extracts on axons growing in vitro. With time, the development of novel in vivo approaches has confirmed the mechanisms highlighted in culture and has led in vitro systems to be adapted for cellular processes that are still inaccessible in intact organisms. We here review the evolution of these in vitro assays, which started with crucial contributions from the Bonhoeffer lab.
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Affiliation(s)
- Oriol Ros
- Universitat de Barcelona, Department of Cell Biology, Physiology and Immunology, Avinguda Diagonal 643, 08028 Barcelona, Catalonia, Spain
| | - Xavier Nicol
- Sorbonne Université, Inserm, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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4
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Su H, Xie T, Liu YU, Cui Y, Wen W, Tang BZ, Qin W. Facile synthesis of ultrabright luminogens with specific lipid droplets targeting feature for in vivo two-photon fluorescence retina imaging. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2022.107949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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5
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Nandamuri SP, Lusk S, Kwan KM. Loss of zebrafish dzip1 results in inappropriate recruitment of periocular mesenchyme to the optic fissure and ocular coloboma. PLoS One 2022; 17:e0265327. [PMID: 35286359 PMCID: PMC8920261 DOI: 10.1371/journal.pone.0265327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/28/2022] [Indexed: 01/13/2023] Open
Abstract
Cilia are essential for the development and function of many different tissues. Although cilia machinery is crucial in the eye for photoreceptor development and function, a role for cilia in early eye development and morphogenesis is still somewhat unclear: many zebrafish cilia mutants retain cilia at early stages due to maternal deposition of cilia components. An eye phenotype has been described in the mouse Arl13 mutant, however, zebrafish arl13b is maternally deposited, and an early role for cilia proteins has not been tested in zebrafish eye development. Here we use the zebrafish dzip1 mutant, which exhibits a loss of cilia throughout stages of early eye development, to examine eye development and morphogenesis. We find that in dzip1 mutants, initial formation of the optic cup proceeds normally, however, the optic fissure subsequently fails to close and embryos develop the structural eye malformation ocular coloboma. Further, neural crest cells, which are implicated in optic fissure closure, do not populate the optic fissure correctly, suggesting that their inappropriate localization may be the underlying cause of coloboma. Overall, our results indicate a role for dzip1 in proper neural crest localization in the optic fissure and optic fissure closure.
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Affiliation(s)
- Sri Pratima Nandamuri
- Department of Human Genetics, University of Utah, Salt Lake City, UT, United States of America
| | - Sarah Lusk
- Department of Human Genetics, University of Utah, Salt Lake City, UT, United States of America
| | - Kristen M. Kwan
- Department of Human Genetics, University of Utah, Salt Lake City, UT, United States of America
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6
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Casey MA, Hill JT, Hoshijima K, Bryan CD, Gribble SL, Brown JT, Chien CB, Yost HJ, Kwan KM. Shutdown corner, a large deletion mutant isolated from a haploid mutagenesis screen in zebrafish. G3 (BETHESDA, MD.) 2022; 12:jkab442. [PMID: 35079792 PMCID: PMC9210284 DOI: 10.1093/g3journal/jkab442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022]
Abstract
Morphogenesis, the formation of three-dimensional organ structures, requires precise coupling of genetic regulation and complex cell behaviors. The genetic networks governing many morphogenetic systems, including that of the embryonic eye, are poorly understood. In zebrafish, several forward genetic screens have sought to identify factors regulating eye development. These screens often look for eye defects at stages after the optic cup is formed and when retinal neurogenesis is under way. This approach can make it difficult to identify mutants specific for morphogenesis, as opposed to neurogenesis. To this end, we carried out a forward genetic, small-scale haploid mutagenesis screen in zebrafish (Danio rerio) to identify factors that govern optic cup morphogenesis. We screened ∼100 genomes and isolated shutdown corner (sco), a mutant that exhibits multiple tissue defects and harbors a ∼10-Mb deletion that encompasses 89 annotated genes. Using a combination of live imaging and antibody staining, we found cell proliferation, cell death, and tissue patterning defects in the sco optic cup. We also observed other phenotypes, including paralysis, neuromuscular defects, and ocular vasculature defects. To date, the largest deletion mutants reported in zebrafish are engineered using CRISPR-Cas9 and are less than 300 kb. Because of the number of genes within the deletion interval, shutdown corner [Df(Chr05:sco)z207] could be a useful resource to the zebrafish community, as it may be helpful for gene mapping, understanding genetic interactions, or studying many genes lost in the mutant.
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Affiliation(s)
- Macaulie A Casey
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Jonathon T Hill
- Department of Cell Biology and Physiology, Brigham Young University, Provo, UT 84602, USA
| | - Kazuyuki Hoshijima
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Chase D Bryan
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32611, USA
| | - Suzanna L Gribble
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - J Thomas Brown
- Department of Biomedical Informatics, Vanderbilt University, Nashville, TN 37203, USA
| | - Chi-Bin Chien
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA
| | - H Joseph Yost
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Kristen M Kwan
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
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7
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Spead O, Weaver CJ, Moreland T, Poulain FE. Live imaging of retinotectal mapping reveals topographic map dynamics and a previously undescribed role for Contactin 2 in map sharpening. Development 2021; 148:272618. [PMID: 34698769 DOI: 10.1242/dev.199584] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 10/07/2021] [Indexed: 11/20/2022]
Abstract
Organization of neuronal connections into topographic maps is essential for processing information. Yet, our understanding of topographic mapping has remained limited by our inability to observe maps forming and refining directly in vivo. Here, we used Cre-mediated recombination of a new colorswitch reporter in zebrafish to generate the first transgenic model allowing the dynamic analysis of retinotectal mapping in vivo. We found that the antero-posterior retinotopic map forms early but remains dynamic, with nasal and temporal retinal axons expanding their projection domains over time. Nasal projections initially arborize in the anterior tectum but progressively refine their projection domain to the posterior tectum, leading to the sharpening of the retinotopic map along the antero-posterior axis. Finally, using a CRISPR-mediated mutagenesis approach, we demonstrate that the refinement of nasal retinal projections requires the adhesion molecule Contactin 2. Altogether, our study provides the first analysis of a topographic map maturing in real time in a live animal and opens new strategies for dissecting the molecular mechanisms underlying precise topographic mapping in vertebrates.
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Affiliation(s)
- Olivia Spead
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Cory J Weaver
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Trevor Moreland
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Fabienne E Poulain
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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8
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Slit2 is necessary for optic axon organization in the zebrafish ventral midline. Cells Dev 2021; 166:203677. [PMID: 33994352 DOI: 10.1016/j.cdev.2021.203677] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 02/07/2023]
Abstract
Slit-Robo signaling has been implicated in regulating several steps of retinal ganglion cell axon guidance, with a central role assigned to Slit2. We report here the phenotypical characterization of a CRISPR-Cas9-generated zebrafish null mutant for this gene, along with a detailed analysis of its expression pattern by WM-FISH. All evident defects in the optic axons in slit2-/- mutants were detected outside the retina, coincident with the major sites of expression at the ventral forebrain, around the developing optic nerve and anterior to the optic chiasm/proximal tract. Anterograde axon tracing experiments in zygotic and maternal-zygotic mutants, as well as morphants, showed the occurrence of axon sorting defects, which appeared mild at the optic nerve level, but more severe in the optic chiasm and the proximal tract. A remarkable sorting defect was the usual splitting of one of the optic nerves in two branches that surrounded the contralateral nerve at the chiasm. Although all axons eventually crossed the midline, the retinotopic order appeared lost at the proximal optic tract, to eventually correct distally. Time-lapse analysis demonstrated the sporadic occurrence of axon misrouting at the chiasm level, which could be responsible for the sorting errors. Our results support previous evidence of a channeling role for Slit molecules in retinal ganglion cell axons at the optic nerve, in addition to a function in the segregation of axons coming from each nerve and from different retinal regions at the medio-ventral area of the forebrain.
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9
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Baier H. Friedrich Bonhoeffer (1932–2021). Neuron 2021. [DOI: 10.1016/j.neuron.2021.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Drescher U. Obituary: Friedrich Bonhoeffer (1932-2021). Development 2021. [PMID: 33632717 DOI: 10.1242/dev.199522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary: Uwe Drescher commemorates the life and work of Friedrich Bonhoeffer, whose pioneering work – including the development of innovative in vitro assays – led to important discoveries in the field of axon guidance and neural development.
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Affiliation(s)
- Uwe Drescher
- Centre for Developmental Neurobiology, MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London, New Hunt's House, Guy's Campus, London SE1 1UL, UK
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11
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Guggiana Nilo DA, Riegler C, Hübener M, Engert F. Distributed chromatic processing at the interface between retina and brain in the larval zebrafish. Curr Biol 2021; 31:1945-1953.e5. [PMID: 33636122 DOI: 10.1016/j.cub.2021.01.088] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 12/30/2020] [Accepted: 01/25/2021] [Indexed: 02/07/2023]
Abstract
Larval zebrafish (Danio rerio) are an ideal organism for studying color vision, as their retina possesses four types of cone photoreceptors, covering most of the visible range and into the UV.1,2 Additionally, their eye and nervous systems are accessible to imaging, given that they are naturally transparent.3-5 Recent studies have found that, through a set of wavelength-range-specific horizontal, bipolar, and retinal ganglion cells (RGCs),6-9 the eye relays tetrachromatic information to several retinorecipient areas (RAs).10-13 The main RA is the optic tectum, receiving 97% of the RGC axons via the neuropil mass termed arborization field 10 (AF10).14,15 Here, we aim to understand the processing of chromatic signals at the interface between RGCs and their major brain targets. We used 2-photon calcium imaging to separately measure the responses of RGCs and neurons in the brain to four different chromatic stimuli in awake animals. We find that chromatic information is widespread throughout the brain, with a large variety of responses among RGCs, and an even greater diversity in their targets. Specific combinations of response types are enriched in specific nuclei, but there is no single color processing structure. In the main interface in this pathway, the connection between AF10 and tectum, we observe key elements of neural processing, such as enhanced signal decorrelation and improved chromatic decoding.16,17 A richer stimulus set revealed that these enhancements occur in the context of a more distributed code in tectum, facilitating chromatic signal association in this small vertebrate brain.
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Affiliation(s)
- Drago A Guggiana Nilo
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Biophysics Graduate Program, Harvard University, Boston, MA 02115, USA; Department Synapses-Circuits-Plasticity, Max Planck Institute of Neurobiology, 81252 Martinsried, Germany.
| | - Clemens Riegler
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Neuroscience and Developmental Biology, University of Vienna, A-1090 Vienna, Austria
| | - Mark Hübener
- Department Synapses-Circuits-Plasticity, Max Planck Institute of Neurobiology, 81252 Martinsried, Germany
| | - Florian Engert
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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12
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Corkins ME, Krneta-Stankic V, Kloc M, Miller RK. Aquatic models of human ciliary diseases. Genesis 2021; 59:e23410. [PMID: 33496382 PMCID: PMC8593908 DOI: 10.1002/dvg.23410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 11/06/2022]
Abstract
Cilia are microtubule-based structures that either transmit information into the cell or move fluid outside of the cell. There are many human diseases that arise from malfunctioning cilia. Although mammalian models provide vital insights into the underlying pathology of these diseases, aquatic organisms such as Xenopus and zebrafish provide valuable tools to help screen and dissect out the underlying causes of these diseases. In this review we focus on recent studies that identify or describe different types of human ciliopathies and outline how aquatic organisms have aided our understanding of these diseases.
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Affiliation(s)
- Mark E. Corkins
- Department of Pediatrics, Pediatric Research Center, UTHealth McGovern Medical School, Houston Texas 77030
| | - Vanja Krneta-Stankic
- Department of Pediatrics, Pediatric Research Center, UTHealth McGovern Medical School, Houston Texas 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Genes & Development, Houston Texas 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Genetics & Epigenetics, Houston, Texas 77030
| | - Malgorzata Kloc
- Houston Methodist, Research Institute, Houston Texas 77030
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston Texas 77030
| | - Rachel K. Miller
- Department of Pediatrics, Pediatric Research Center, UTHealth McGovern Medical School, Houston Texas 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Genetics & Epigenetics, Houston, Texas 77030
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston Texas 77030
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Program in Biochemistry & Cell Biology, Houston Texas 77030
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13
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Fuhrmann JF, Buono L, Adelmann L, Martinez-Morales JR, Centanin L. Genetic developmental timing revealed by inter-species transplantations in fish. Development 2020; 147:dev.192500. [PMID: 33033120 DOI: 10.1242/dev.192500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/02/2020] [Indexed: 12/22/2022]
Abstract
The path from a fertilised egg to an embryo involves the coordinated formation of cell types, tissues and organs. Developmental modules comprise discrete units specified by self-sufficient genetic programs that can interact with each other during embryogenesis. Here, we have taken advantage of the different span of embryonic development between two distantly related teleosts, zebrafish (Danio rerio) and medaka (Oryzias latipes) (3 and 9 days, respectively), to explore modularity principles. We report that inter-species blastula transplantations result in the ectopic formation of a retina formed by donor cells - a module. We show that the time taken for the retina to develop follows a genetic program: an ectopic zebrafish retina in medaka develops with zebrafish dynamics. Heterologous transplantation results in a temporal decoupling between the donor retina and host organism, illustrated by two paradigms that require retina-host interactions: lens recruitment and retino-tectal projections. Our results uncover a new experimental system for addressing temporal decoupling along embryonic development, and highlight the presence of largely autonomous but interconnected developmental modules that orchestrate organogenesis.
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Affiliation(s)
- Jana Franziska Fuhrmann
- Laboratory of Clonal Analysis, Center for Organismal Studies, Universität Heidelberg, INF230, 69120 Heidelberg, Germany
| | - Lorena Buono
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Carretera de Utrera km 1, 41013 Seville, Spain
| | - Leonie Adelmann
- Laboratory of Clonal Analysis, Center for Organismal Studies, Universität Heidelberg, INF230, 69120 Heidelberg, Germany
| | - Juan Ramón Martinez-Morales
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Carretera de Utrera km 1, 41013 Seville, Spain
| | - Lazaro Centanin
- Laboratory of Clonal Analysis, Center for Organismal Studies, Universität Heidelberg, INF230, 69120 Heidelberg, Germany
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14
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Visuomotor deficiency in panx1a knockout zebrafish is linked to dopaminergic signaling. Sci Rep 2020; 10:9538. [PMID: 32533080 PMCID: PMC7293225 DOI: 10.1038/s41598-020-66378-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 05/15/2020] [Indexed: 12/23/2022] Open
Abstract
Pannexin 1 (Panx1) forms ATP-permeable membrane channels that play roles in the nervous system. The analysis of roles in both standard and pathological conditions benefits from a model organism with rapid development and early onset of behaviors. Such a model was developed by ablating the zebrafish panx1a gene using TALEN technology. Here, RNA-seq analysis of 6 days post fertilization larvae were confirmed by Real-Time PCR and paired with testing visual-motor behavior and in vivo electrophysiology. Results demonstrated that loss of panx1a specifically affected the expression of gene classes representing the development of the visual system and visual processing. Abnormal swimming behavior in the dark and the expression regulation of pre-and postsynaptic biomarkers suggested changes in dopaminergic signaling. Indeed, altered visuomotor behavior in the absence of functional Panx1a was evoked through D1/D2-like receptor agonist treatment and rescued with the D2-like receptor antagonist Haloperidol. Local field potentials recorded from superficial areas of the optic tectum receiving input from the retina confirmed abnormal responses to visual stimuli, which resembled treatments with a dopamine receptor agonist or pharmacological blocking of Panx1a. We conclude that Panx1a functions are relevant at a time point when neuronal networks supporting visual-motor functions undergo modifications preparing for complex behaviors of freely swimming fish.
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15
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Zhang Y, Lee Y, Han K. Neuronal function and dysfunction of CYFIP2: from actin dynamics to early infantile epileptic encephalopathy. BMB Rep 2019. [PMID: 30982501 PMCID: PMC6549915 DOI: 10.5483/bmbrep.2019.52.5.097] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The cytoplasmic FMR1-interacting protein family (CYFIP1 and CYFIP2) are evolutionarily conserved proteins originally identified as binding partners of the fragile X mental retardation protein (FMRP), a messenger RNA (mRNA)-binding protein whose loss causes the fragile X syndrome. Moreover, CYFIP is a key component of the heteropentameric WAVE regulatory complex (WRC), a critical regulator of neuronal actin dynamics. Therefore, CYFIP may play key roles in regulating both mRNA translation and actin polymerization, which are critically involved in proper neuronal development and function. Nevertheless, compared to CYFIP1, neuronal function and dysfunction of CYFIP2 remain largely unknown, possibly due to the relatively less well established association between CYFIP2 and brain disorders. Despite high amino acid sequence homology between CYFIP1 and CYFIP2, several in vitro and animal model studies have suggested that CYFIP2 has some unique neuronal functions distinct from those of CYFIP1. Furthermore, recent whole-exome sequencing studies identified de novo hot spot variants of CYFIP2 in patients with early infantile epileptic encephalopathy (EIEE), clearly implicating CYFIP2 dysfunction in neurological disorders. In this review, we highlight these recent investigations into the neuronal function and dysfunction of CYFIP2, and also discuss several key questions remaining about this intriguing neuronal protein.
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Affiliation(s)
- Yinhua Zhang
- Departments of Neuroscience, and Biomedical Sciences, College of Medicine, Korea University, Seoul 02841, Korea
| | - Yeunkum Lee
- Departments of Neuroscience, and Biomedical Sciences, College of Medicine, Korea University, Seoul 02841, Korea
| | - Kihoon Han
- Departments of Neuroscience, and Biomedical Sciences, College of Medicine, Korea University, Seoul 02841, Korea
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16
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Cioni JM, Wong HHW, Bressan D, Kodama L, Harris WA, Holt CE. Axon-Axon Interactions Regulate Topographic Optic Tract Sorting via CYFIP2-Dependent WAVE Complex Function. Neuron 2019. [PMID: 29518358 PMCID: PMC5855093 DOI: 10.1016/j.neuron.2018.01.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The axons of retinal ganglion cells (RGCs) are topographically sorted before they arrive at the optic tectum. This pre-target sorting, typical of axon tracts throughout the brain, is poorly understood. Here, we show that cytoplasmic FMR1-interacting proteins (CYFIPs) fulfill non-redundant functions in RGCs, with CYFIP1 mediating axon growth and CYFIP2 specifically involved in axon sorting. We find that CYFIP2 mediates homotypic and heterotypic contact-triggered fasciculation and repulsion responses between dorsal and ventral axons. CYFIP2 associates with transporting ribonucleoprotein particles in axons and regulates translation. Axon-axon contact stimulates CYFIP2 to move into growth cones where it joins the actin nucleating WAVE regulatory complex (WRC) in the periphery and regulates actin remodeling and filopodial dynamics. CYFIP2’s function in axon sorting is mediated by its binding to the WRC but not its translational regulation. Together, these findings uncover CYFIP2 as a key regulatory link between axon-axon interactions, filopodial dynamics, and optic tract sorting. CYFIP1 and CYFIP2 serve non-redundant functions in retinal axon growth and guidance CYFIP2 regulates growth cone filopodial dynamics and axon-axon responses CYFIP2 interacts with RNPs and the WRC in distinct cellular compartments Axon sorting is mediated by CYFIP2’s interaction with the WRC
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Affiliation(s)
- Jean-Michel Cioni
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Hovy Ho-Wai Wong
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Dario Bressan
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Lay Kodama
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK.
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17
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Kunst M, Laurell E, Mokayes N, Kramer A, Kubo F, Fernandes AM, Förster D, Dal Maschio M, Baier H. A Cellular-Resolution Atlas of the Larval Zebrafish Brain. Neuron 2019; 103:21-38.e5. [DOI: 10.1016/j.neuron.2019.04.034] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 04/10/2019] [Accepted: 04/23/2019] [Indexed: 02/06/2023]
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18
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Fuentes R, Letelier J, Tajer B, Valdivia LE, Mullins MC. Fishing forward and reverse: Advances in zebrafish phenomics. Mech Dev 2018; 154:296-308. [PMID: 30130581 PMCID: PMC6289646 DOI: 10.1016/j.mod.2018.08.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 08/06/2018] [Accepted: 08/17/2018] [Indexed: 12/15/2022]
Abstract
Understanding how the genome instructs the phenotypic characteristics of an organism is one of the major scientific endeavors of our time. Advances in genetics have progressively deciphered the inheritance, identity and biological relevance of genetically encoded information, contributing to the rise of several, complementary omic disciplines. One of them is phenomics, an emergent area of biology dedicated to the systematic multi-scale analysis of phenotypic traits. This discipline provides valuable gene function information to the rapidly evolving field of genetics. Current molecular tools enable genome-wide analyses that link gene sequence to function in multi-cellular organisms, illuminating the genome-phenome relationship. Among vertebrates, zebrafish has emerged as an outstanding model organism for high-throughput phenotyping and modeling of human disorders. Advances in both systematic mutagenesis and phenotypic analyses of embryonic and post-embryonic stages in zebrafish have revealed the function of a valuable collection of genes and the general structure of several complex traits. In this review, we summarize multiple large-scale genetic efforts addressing parental, embryonic, and adult phenotyping in the zebrafish. The genetic and quantitative tools available in the zebrafish model, coupled with the broad spectrum of phenotypes that can be assayed, make it a powerful model for phenomics, well suited for the dissection of genotype-phenotype associations in development, physiology, health and disease.
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Affiliation(s)
- Ricardo Fuentes
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joaquín Letelier
- Centro Andaluz de Biología del Desarrollo (CSIC/UPO/JA), Seville, Spain; Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Benjamin Tajer
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Leonardo E Valdivia
- Center for Integrative Biology, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.
| | - Mary C Mullins
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Di Donato V, De Santis F, Albadri S, Auer TO, Duroure K, Charpentier M, Concordet JP, Gebhardt C, Del Bene F. An Attractive Reelin Gradient Establishes Synaptic Lamination in the Vertebrate Visual System. Neuron 2018; 97:1049-1062.e6. [PMID: 29429939 DOI: 10.1016/j.neuron.2018.01.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 11/11/2017] [Accepted: 01/11/2018] [Indexed: 10/18/2022]
Abstract
A conserved organizational and functional principle of neural networks is the segregation of axon-dendritic synaptic connections into laminae. Here we report that targeting of synaptic laminae by retinal ganglion cell (RGC) arbors in the vertebrate visual system is regulated by a signaling system relying on target-derived Reelin and VLDLR/Dab1a on the projecting neurons. Furthermore, we find that Reelin is distributed as a gradient on the target tissue and stabilized by heparan sulfate proteoglycans (HSPGs) in the extracellular matrix (ECM). Through genetic manipulations, we show that this Reelin gradient is important for laminar targeting and that it is attractive for RGC axons. Finally, we suggest a comprehensive model of synaptic lamina formation in which attractive Reelin counter-balances repulsive Slit1, thereby guiding RGC axons toward single synaptic laminae. We establish a mechanism that may represent a general principle for neural network assembly in vertebrate species and across different brain areas.
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Affiliation(s)
- Vincenzo Di Donato
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France
| | - Flavia De Santis
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France
| | - Shahad Albadri
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France
| | - Thomas Oliver Auer
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France
| | - Karine Duroure
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France
| | - Marine Charpentier
- Muséum National d'Histoire Naturelle, INSERM U1154, CNRS UMR7196, Paris 75231, France
| | - Jean-Paul Concordet
- Muséum National d'Histoire Naturelle, INSERM U1154, CNRS UMR7196, Paris 75231, France
| | - Christoph Gebhardt
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France.
| | - Filippo Del Bene
- Institut Curie, PSL Research University, INSERM U934, CNRS UMR3215, UPMC Paris-Sorbonne, Paris 75005, France.
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Abstract
In the last 30 years, the zebrafish has become a widely used model organism for research on vertebrate development and disease. Through a powerful combination of genetics and experimental embryology, significant inroads have been made into the regulation of embryonic axis formation, organogenesis, and the development of neural networks. Research with this model has also expanded into other areas, including the genetic regulation of aging, regeneration, and animal behavior. Zebrafish are a popular model because of the ease with which they can be maintained, their small size and low cost, the ability to obtain hundreds of embryos on a daily basis, and the accessibility, translucency, and rapidity of early developmental stages. This primer describes the swift progress of genetic approaches in zebrafish and highlights recent advances that have led to new insights into vertebrate biology.
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Abstract
OBJECTIVES Axon tracers provide crucial insight into the development, connectivity, and function of neural pathways. A tracer can be characterized as a substance that allows for the visualization of a neuronal pathway. Axon tracers have previously been used exclusively with in vivo studies; however, newer methods of axon tracing can be applied to ex vivo studies. Ex vivo studies involve the examination of cells or tissues retrieved from an organism. These post mortem methods of axon tracing offer several advantages, such as reaching inaccessible tissues and avoiding survival surgeries. METHODS In order to evaluate the quality of the ex vivo tracing methods, we performed a systematic review of various experimental and comparison studies to discern the optimal method of axon tracing. RESULTS The most prominent methods for ex vivo tracing involve enzymatic techniques or various dyes. It appears that there are a variety of techniques and conditions that tend to give better fluorescent character, clarity, and distance traveled in the neuronal pathway. We found direct comparison studies that looked at variables such as the type of tracer, time required, effect of temperature, and presence of calcium, however, there are other variables that have not been compared directly. DISCUSSION We conclude there are a variety of promising tracing methods available depending on the experimental goals of the researcher, however, more direct comparison studies are needed to affirm the optimal method.
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Affiliation(s)
| | - Matthew B Jensen
- a Department of Neurology , University of Wisconsin-Madison , Madison , WI , USA
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22
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Samuel A, Rubinstein AM, Azar TT, Ben-Moshe Livne Z, Kim SH, Inbal A. Six3 regulates optic nerve development via multiple mechanisms. Sci Rep 2016; 6:20267. [PMID: 26822689 PMCID: PMC4731751 DOI: 10.1038/srep20267] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 12/30/2015] [Indexed: 12/05/2022] Open
Abstract
Malformations of the optic nerve lead to reduced vision or even blindness. During optic nerve development, retinal ganglion cell (RGC) axons navigate across the retina, exit the eye to the optic stalk (OS), and cross the diencephalon midline at the optic chiasm en route to their brain targets. Many signalling molecules have been implicated in guiding various steps of optic nerve pathfinding, however much less is known about transcription factors regulating this process. Here we show that in zebrafish, reduced function of transcription factor Six3 results in optic nerve hypoplasia and a wide repertoire of RGC axon pathfinding errors. These abnormalities are caused by multiple mechanisms, including abnormal eye and OS patterning and morphogenesis, abnormal expression of signalling molecules both in RGCs and in their environment and anatomical deficiency in the diencephalic preoptic area, where the optic chiasm normally forms. Our findings reveal new roles for Six3 in eye development and are consistent with known phenotypes of reduced SIX3 function in humans. Hence, the new zebrafish model for Six3 loss of function furthers our understanding of the mechanisms governing optic nerve development and Six3-mediated eye and forebrain malformations.
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Affiliation(s)
- Anat Samuel
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Ariel M. Rubinstein
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Tehila T. Azar
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Zohar Ben-Moshe Livne
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Seok-Hyung Kim
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Adi Inbal
- Department of Medical Neurobiology, Institute for Medical Research - Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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23
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24
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Auer TO, Xiao T, Bercier V, Gebhardt C, Duroure K, Concordet JP, Wyart C, Suster M, Kawakami K, Wittbrodt J, Baier H, Del Bene F. Deletion of a kinesin I motor unmasks a mechanism of homeostatic branching control by neurotrophin-3. eLife 2015; 4. [PMID: 26076409 PMCID: PMC4467164 DOI: 10.7554/elife.05061] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 05/18/2015] [Indexed: 12/14/2022] Open
Abstract
Development and function of highly polarized cells such as neurons depend on microtubule-associated intracellular transport, but little is known about contributions of specific molecular motors to the establishment of synaptic connections. In this study, we investigated the function of the Kinesin I heavy chain Kif5aa during retinotectal circuit formation in zebrafish. Targeted disruption of Kif5aa does not affect retinal ganglion cell differentiation, and retinal axons reach their topographically correct targets in the tectum, albeit with a delay. In vivo dynamic imaging showed that anterograde transport of mitochondria is impaired, as is synaptic transmission. Strikingly, disruption of presynaptic activity elicits upregulation of Neurotrophin-3 (Ntf3) in postsynaptic tectal cells. This in turn promotes exuberant branching of retinal axons by signaling through the TrkC receptor (Ntrk3). Thus, our study has uncovered an activity-dependent, retrograde signaling pathway that homeostatically controls axonal branching.
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Affiliation(s)
| | - Tong Xiao
- Department of Physiology, University of California San Francisco, San Francisco, United States
| | | | | | | | - Jean-Paul Concordet
- Muséum National d'Histoire naturelle, Inserm U 1154, CNRS, UMR 7196, Muséum National d'Histoire Naturelle, Paris, France
| | - Claire Wyart
- Institut du Cerveau et de la Moelle épinière, ICM, Inserm U 1127, CNRS, UMR 7225, Sorbonne Universités, UPMC University Paris 6, Paris, France
| | - Maximiliano Suster
- Neural Circuits and Behaviour Group, Uni Research AS High Technology Centre, Bergen, Norway
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Shizuoka, Japan
| | - Joachim Wittbrodt
- Centre for Organismal Studies, University of Heidelberg, Heidelberg, Germany
| | - Herwig Baier
- Department of Physiology, University of California San Francisco, San Francisco, United States
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25
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Faller KME, Gutierrez-Quintana R, Mohammed A, Rahim AA, Tuxworth RI, Wager K, Bond M. The neuronal ceroid lipofuscinoses: Opportunities from model systems. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2267-78. [PMID: 25937302 DOI: 10.1016/j.bbadis.2015.04.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/13/2015] [Accepted: 04/22/2015] [Indexed: 12/16/2022]
Abstract
The neuronal ceroid lipofuscinoses are a group of severe and progressive neurodegenerative disorders, generally with childhood onset. Despite the fact that these diseases remain fatal, significant breakthroughs have been made in our understanding of the genetics that underpin these conditions. This understanding has allowed the development of a broad range of models to study disease processes, and to develop new therapeutic approaches. Such models have contributed significantly to our knowledge of these conditions. In this review we will focus on the advantages of each individual model, describe some of the contributions the models have made to our understanding of the broader disease biology and highlight new techniques and approaches relevant to the study and potential treatment of the neuronal ceroid lipofuscinoses. This article is part of a Special Issue entitled: "Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease)".
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Affiliation(s)
- Kiterie M E Faller
- School of Veterinary Medicine, College of Veterinary, Medical and Life Sciences, Bearsden Road, Glasgow G61 1QH, UK
| | - Rodrigo Gutierrez-Quintana
- School of Veterinary Medicine, College of Veterinary, Medical and Life Sciences, Bearsden Road, Glasgow G61 1QH, UK
| | - Alamin Mohammed
- College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Ahad A Rahim
- UCL School of Pharmacy, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Richard I Tuxworth
- College of Medical and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Kim Wager
- Cardiff School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff CF10 3AX, UK
| | - Michael Bond
- MRC Laboratory for Molecular Cell Biology, University College of London, Gower Street, London WC1E 6BT, UK.
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26
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Kita EM, Scott EK, Goodhill GJ. Topographic wiring of the retinotectal connection in zebrafish. Dev Neurobiol 2015; 75:542-56. [PMID: 25492632 DOI: 10.1002/dneu.22256] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/03/2014] [Accepted: 12/08/2014] [Indexed: 11/08/2022]
Abstract
The zebrafish retinotectal projection provides an attractive model system for studying many aspects of topographic map formation and maintenance. Visual connections initially start to form between 3 and 5 days postfertilization, and remain plastic throughout the life of the fish. Zebrafish are easily manipulated surgically, genetically, and chemically, and a variety of molecular tools exist to enable visualization and control of various aspects of map development. Here, we review zebrafish retinotectal map formation, focusing particularly on the detailed structure and dynamics of the connections, the molecules that are important in map creation, and how activity regulates the maintenance of the map.
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Affiliation(s)
- Elizabeth M Kita
- Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia
| | - Ethan K Scott
- School of Biomedical Sciences, The University of Queensland, Brisbane QLD 4072, Australia
| | - Geoffrey J Goodhill
- Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia.,School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia
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27
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Belle M, Godefroy D, Dominici C, Heitz-Marchaland C, Zelina P, Hellal F, Bradke F, Chédotal A. A simple method for 3D analysis of immunolabeled axonal tracts in a transparent nervous system. Cell Rep 2014; 9:1191-201. [PMID: 25456121 DOI: 10.1016/j.celrep.2014.10.037] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 11/16/2022] Open
Abstract
Clearing techniques have been developed to transparentize mouse brains, thereby preserving 3D structure, but their complexity has limited their use. Here, we show that immunolabeling of axonal tracts followed by optical clearing with solvents (3DISCO) and light-sheet microscopy reveals brain connectivity in mouse embryos and postnatal brains. We show that the Robo3 receptor is selectively expressed by medial habenula axons forming the fasciculus retroflexus (FR) and analyzed the development of this commissural tract in mutants of the Slit/Robo and DCC/Netrin pathways. Netrin-1 and DCC are required to attract FR axons to the midline, but the two mutants exhibit specific and heterogeneous axon guidance defects. Moreover, floor-plate-specific deletion of Slit ligands with a conditional Slit2 allele perturbs not only midline crossing by FR axons but also their anteroposterior distribution. In conclusion, this method represents a unique and powerful imaging tool to study axonal connectivity in mutant mice.
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Affiliation(s)
- Morgane Belle
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France
| | - David Godefroy
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France
| | - Chloé Dominici
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France
| | - Céline Heitz-Marchaland
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France
| | - Pavol Zelina
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France
| | - Farida Hellal
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Axon Growth and Regeneration, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Frank Bradke
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Axon Growth and Regeneration, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Alain Chédotal
- Sorbonne Universités, UPMC Université Paris 06, UMRS 968, Institut de la Vision, Paris 75012, France; INSERM, UMRS 968, Institut de la Vision, Paris 75012, France; CNRS, UMR 7210, Paris 75012, France.
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28
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Wager K, Mahmood F, Russell C. Modelling inborn errors of metabolism in zebrafish. J Inherit Metab Dis 2014; 37:483-95. [PMID: 24797558 DOI: 10.1007/s10545-014-9696-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/13/2014] [Accepted: 02/17/2014] [Indexed: 12/22/2022]
Abstract
The majority of human inborn errors of metabolism are fatal multisystem disorders that lack proper treatment and have a poorly understood mechanistic basis. Novel technologies are required to address this issue, and the use of zebrafish to model these diseases is an emerging field. Here we present the published zebrafish models of inborn metabolic diseases, discuss their validity, and review the novel mechanistic insights that they have provided. We also review the available methods for creating and studying zebrafish disease models, advantages and disadvantages of using this model organism, and successful examples of the use of zebrafish for drug discovery and development. Using a zebrafish to model inborn errors of metabolism in vivo, although still in its infancy, shows promise for a deeper understanding of disease pathomechanisms, onset, and progression, and also for the development of specific therapies.
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Affiliation(s)
- Kim Wager
- Department of Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London, NW1 0TU, UK
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29
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Poulain FE, Chien CB. Proteoglycan-mediated axon degeneration corrects pretarget topographic sorting errors. Neuron 2013; 78:49-56. [PMID: 23583107 DOI: 10.1016/j.neuron.2013.02.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2013] [Indexed: 11/16/2022]
Abstract
Proper arrangement of axonal projections into topographic maps is crucial for brain function, especially in sensory systems. An important mechanism for map formation is pretarget axon sorting, in which topographic ordering of axons appears in tracts before axons reach their target, but this process remains poorly understood. Here, we show that selective axon degeneration is used as a correction mechanism to eliminate missorted axons in the optic tract during retinotectal development in zebrafish. Retinal axons are not precisely ordered during initial pathfinding but become corrected later, with missorted axons selectively fragmenting and degenerating. We further show that heparan sulfate is required non-cell-autonomously to correct missorted axons and that restoring its synthesis at late stages in a deficient mutant is sufficient to restore topographic sorting. These findings uncover a function for developmental axon degeneration in ordering axonal projections and identify heparan sulfate as a key regulator of that process.
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Affiliation(s)
- Fabienne E Poulain
- University of Utah, Neurobiology and Anatomy Department, Salt Lake City, UT 84132, USA.
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30
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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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31
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Muto A, Ohkura M, Abe G, Nakai J, Kawakami K. Real-time visualization of neuronal activity during perception. Curr Biol 2013; 23:307-11. [PMID: 23375894 DOI: 10.1016/j.cub.2012.12.040] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 12/23/2012] [Accepted: 12/24/2012] [Indexed: 10/27/2022]
Abstract
To understand how the brain perceives the external world, it is desirable to observe neuronal activity in the brain in real time during perception. The zebrafish is a suitable model animal for fluorescence imaging studies to visualize neuronal activity because its body is transparent through the embryonic and larval stages. Imaging studies have been carried out to monitor neuronal activity in the larval spinal cord and brain using Ca(2+) indicator dyes and DNA-encoded Ca(2+) indicators, such as Cameleon, GFP-aequorin, and GCaMPs. However, temporal and spatial resolution and sensitivity of these tools are still limited, and imaging of brain activity during perception of a natural object has not yet been demonstrated. Here we demonstrate visualization of neuronal activity in the optic tectum of larval zebrafish by genetically expressing the new version of GCaMP. First, we demonstrate Ca(2+) transients in the tectum evoked by a moving spot on a display and identify direction-selective neurons. Second, we show tectal activity during perception of a natural object, a swimming paramecium, revealing a functional visuotopic map. Finally, we image the tectal responses of a free-swimming larval fish to a paramecium and thereby correlate neuronal activity in the brain with prey capture behavior.
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Affiliation(s)
- Akira Muto
- Division of Molecular and Developmental Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
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32
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Abstract
In December 1996, a special issue of Development appeared that presented in 37 papers the results of two large screens for zebrafish mutants performed in Tübingen and Boston. The papers describe about 1500 mutations in more than 400 new genes involved in a wide range of processes that govern development and organogenesis. Up to this day, the mutants provide a rich resource for many laboratories, and the issue significantly augmented the importance of zebrafish as vertebrate model organism for the study of embryogenesis, neuronal networks, regeneration and disease. This essay relates a personal account of the history of this unique endeavor.
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Abstract
The study of nervous system development has been greatly facilitated by recent advances in molecular biology and imaging techniques. These approaches are perfectly suited to young transparent zebrafish where they have allowed direct observation of neural circuit assembly in vivo. In this review we will highlight a number of key studies that have applied optical and genetic techniques in zebrafish to address questions relating to axonal and dendritic arbor development,synapse assembly and neural plasticity. These studies have revealed novel cellular phenomena and modes of growth that may reflect general principles governing the assembly of neural circuits.
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Affiliation(s)
- Nikolas Nikolaou
- King's College London, Guy's Hospital Campus, London SE1 1UL, UK
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34
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Flanagan-Steet HR, Steet R. "Casting" light on the role of glycosylation during embryonic development: insights from zebrafish. Glycoconj J 2012; 30:33-40. [PMID: 22638861 DOI: 10.1007/s10719-012-9390-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 04/23/2012] [Accepted: 04/25/2012] [Indexed: 12/23/2022]
Abstract
Zebrafish (Danio rerio) remains a versatile model organism for the investigation of early development and organogenesis, and has emerged as a valuable platform for drug discovery and toxicity evaluation [1-6]. Harnessing the genetic power and experimental accessibility of this system, three decades of research have identified key genes and pathways that control the development of multiple organ systems and tissues, including the heart, kidney, and craniofacial cartilage, as well as the hematopoietic, vascular, and central and peripheral nervous systems [7-31]. In addition to their application in large mutagenic screens, zebrafish has been used to model a variety of diseases such as diabetes, polycystic kidney disease, muscular dystrophy and cancer [32-36]. As this work continues to intersect with cellular pathways and processes such as lipid metabolism, glycosylation and vesicle trafficking, investigators are often faced with the challenge of determining the degree to which these pathways are functionally conserved in zebrafish. While they share a high degree of genetic homology with mouse and human, the manner in which cellular pathways are regulated in zebrafish during early development, and the differences in the organ physiology, warrant consideration before functional studies can be effectively interpreted and compared with other vertebrate systems. This point is particularly relevant for glycosylation since an understanding of the glycan diversity and the mechanisms that control glycan biosynthesis during zebrafish embryogenesis (as in many organisms) is still developing.Nonetheless, a growing number of studies in zebrafish have begun to cast light on the functional roles of specific classes of glycans during organ and tissue development. While many of the initial efforts involved characterizing identified mutants in a number of glycosylation pathways, the use of reverse genetic approaches to directly model glycosylation-related disorders is now increasingly popular. In this review, the glycomics of zebrafish and the developmental expression of their glycans will be briefly summarized along with recent chemical biology approaches to visualize certain classes of glycans within developing embryos. Work regarding the role of protein-bound glycans and glycosaminoglycans (GAG) in zebrafish development and organogenesis will also be highlighted. Lastly, future opportunities and challenges in the expanding field of zebrafish glycobiology are discussed.
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Rimon N, Schuldiner M. Getting the whole picture: combining throughput with content in microscopy. J Cell Sci 2012; 124:3743-51. [PMID: 22124141 DOI: 10.1242/jcs.087486] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The increasing availability and performance of automated scientific equipment in the past decades have brought about a revolution in the biological sciences. The ease with which data can now be generated has led to a new culture of high-throughput science, in which new types of biological questions can be asked and tackled in a systematic and unbiased manner. High-throughput microscopy, also often referred to as high-content screening (HCS), allows acquisition of systematic data at the single-cell level. Moreover, it allows the visualization of an enormous array of cellular features and provides tools to quantify a large number of parameters for each cell. These features make HCS a powerful method to create data that is rich and biologically meaningful without compromising systematic capabilities. In this Commentary, we will discuss recent work, which has used HCS, to demonstrate the diversity of applications and technological solutions that are evolving in this field. Such advances are placing HCS methodologies at the frontier of high-throughput science and enable scientists to combine throughput with content to address a variety of cell biological questions.
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Affiliation(s)
- Nitzan Rimon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel 76100
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36
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Cowden J, Padnos B, Hunter D, MacPhail R, Jensen K, Padilla S. Developmental exposure to valproate and ethanol alters locomotor activity and retino-tectal projection area in zebrafish embryos. Reprod Toxicol 2012; 33:165-73. [PMID: 22244950 DOI: 10.1016/j.reprotox.2011.11.111] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 11/03/2011] [Accepted: 11/24/2011] [Indexed: 11/17/2022]
Abstract
Given the minimal developmental neurotoxicity data available for the large number of new and existing chemicals, there is a critical need for alternative methods to identify and prioritize chemicals for further testing. We outline a developmental neurotoxicity screening approach using zebrafish embryos. Embryos were exposed to nominal concentrations of either valproate or ethanol then examined for lethality, malformation, nervous system structure and locomotor activity. Developmental valproate exposure caused locomotor activity changes at concentrations that did not result in malformations and showed a concentration-dependent decrease in retino-tectal projection area in the optic tectum. Developmental ethanol exposure also affected retino-tectal projection area at concentrations below those concentrations causing malformations. As both valproate and ethanol are known human developmental neurotoxicants, these results add to the growing body of evidence showing the potential utility of zebrafish in screening compounds for mammalian developmental neurotoxicity.
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Affiliation(s)
- John Cowden
- Integrated Systems Toxicology Division United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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37
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Huang MYY, Chen CC, Huber-Reggi SP, Neuhauss SCF, Straumann D. Comparison of infantile nystagmus syndrome in achiasmatic zebrafish and humans. Ann N Y Acad Sci 2011; 1233:285-91. [PMID: 21951006 DOI: 10.1111/j.1749-6632.2011.06150.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Infantile nystagmus syndrome (INS; formerly called congenital nystagmus) is an ocular motor disorder characterized by several typical nystagmus waveforms. To date, restrictions inherent to human research and the absence of a handy animal model have impeded efforts to identify the underlying mechanism of INS. Displaying INS-like spontaneous eye oscillations, achiasmatic zebrafish belladonna (bel) mutants may provide new insights into the mystery of INS. In this study, we demonstrate that these spontaneous eye oscillations match the diagnostic waveforms of INS. As a result, zebrafish bel mutants can be used as an animal model for the study of INS. In zebrafish bel mutants, visual pathway abnormalities may contribute to the spontaneous nystagmus via an inverted signal to the pretectal area. We hypothesized that human INS may also be linked to visual pathway abnormalities (possibly underdiagnosed in INS patients) in a similar way.
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38
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Xiao T, Staub W, Robles E, Gosse NJ, Cole GJ, Baier H. Assembly of lamina-specific neuronal connections by slit bound to type IV collagen. Cell 2011; 146:164-76. [PMID: 21729787 DOI: 10.1016/j.cell.2011.06.016] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 04/10/2011] [Accepted: 06/09/2011] [Indexed: 01/08/2023]
Abstract
The mechanisms that generate specific neuronal connections in the brain are under intense investigation. In zebrafish, retinal ganglion cells project their axons into at least six layers within the neuropil of the midbrain tectum. Each axon elaborates a single, planar arbor in one of the target layers and forms synapses onto the dendrites of tectal neurons. We show that the laminar specificity of retinotectal connections does not depend on self-sorting interactions among RGC axons. Rather, tectum-derived Slit1, signaling through axonal Robo2, guides neurites to their target layer. Genetic and biochemical studies indicate that Slit binds to Dragnet (Col4a5), a type IV Collagen, which forms the basement membrane on the surface of the tectum. We further show that radial glial endfeet are required for the basement-membrane anchoring of Slit. We propose that Slit1 signaling, perhaps in the form of a superficial-to-deep gradient, presents laminar positional cues to ingrowing retinal axons.
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Affiliation(s)
- Tong Xiao
- Programs in Neuroscience, Department of Physiology, University of California, San Francisco, 1550 Fourth Street, San Francisco, CA 94158-2722, USA
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39
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Renninger SL, Schonthaler HB, Neuhauss SCF, Dahm R. Investigating the genetics of visual processing, function and behaviour in zebrafish. Neurogenetics 2011; 12:97-116. [PMID: 21267617 DOI: 10.1007/s10048-011-0273-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 01/04/2011] [Indexed: 12/11/2022]
Abstract
Over the past three decades, the zebrafish has been proven to be an excellent model to investigate the genetic control of vertebrate embryonic development, and it is now also increasingly used to study behaviour and adult physiology. Moreover, mutagenesis approaches have resulted in large collections of mutants with phenotypes that resemble human pathologies, suggesting that these lines can be used to model diseases and screen drug candidates. With the recent development of new methods for gene targeting and manipulating or monitoring gene expression, the range of genetic modifications now possible in zebrafish is increasing rapidly. Combined with the classical strengths of the zebrafish as a model organism, these advances are set to substantially expand the type of biological questions that can be addressed in this species. In this review, we outline how the potential of the zebrafish can be harvested in the context of eye development and visual function. We review recent technological advances used to study the formation of the eyes and visual areas of the brain, visual processing on the cellular, subcellular and molecular level, and the genetics of visual behaviour in vertebrates.
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Affiliation(s)
- Sabine L Renninger
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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40
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Rinkwitz S, Mourrain P, Becker TS. Zebrafish: an integrative system for neurogenomics and neurosciences. Prog Neurobiol 2010; 93:231-43. [PMID: 21130139 DOI: 10.1016/j.pneurobio.2010.11.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 11/08/2010] [Accepted: 11/22/2010] [Indexed: 10/18/2022]
Abstract
Rapid technological advances over the past decade have moved us closer to a high throughput molecular approach to neurobiology, where we see the merging of neurogenetics, genomics, physiology, imaging and pharmacology. This is the case more in zebrafish than in any other model organism commonly used. Recent improvements in the generation of transgenic zebrafish now allow genetic manipulation and live imaging of neuronal development and function in early embryonic, larval, and adult animals. The sequenced zebrafish genome and comparative genomics give unprecedented insights into genome evolution and its relation to genome structure and function. There is now information on embryonic and larval expression of over 12,000 genes and just under 1000 mutant phenotypes. We review the remarkable similarity of the zebrafish genetic blueprint for the nervous system to that of mammals and assess recent technological advances that make the zebrafish a model of choice for elucidating the development and function of neuronal circuitry, transgene-based neuroanatomy, and small molecule neuropharmacology.
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Affiliation(s)
- Silke Rinkwitz
- Brain and Mind Research Institute, Sydney Medical School, University of Sydney, 100 Mallett St., Camperdown, NSW 2050, Australia
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41
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Bergeron SA, Tyurina OV, Miller E, Bagas A, Karlstrom RO. Brother of cdo (umleitung) is cell-autonomously required for Hedgehog-mediated ventral CNS patterning in the zebrafish. Development 2010; 138:75-85. [PMID: 21115611 DOI: 10.1242/dev.057950] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The transmembrane protein Brother of Cdo (Boc) has been implicated in Shh-mediated commissural axon guidance, and can both positively and negatively regulate Hedgehog (Hh) target gene transcription, however, little is known about in vivo requirements for Boc during vertebrate embryogenesis. The zebrafish umleitung (uml(ty54)) mutant was identified by defects in retinotectal axon projections. Here, we show that the uml locus encodes Boc and that Boc function is cell-autonomously required for Hh-mediated neural patterning. Our phenotypic analysis suggests that Boc is required as a positive regulator of Hh signaling in the spinal cord, hypothalamus, pituitary, somites and upper jaw, but that Boc might negatively regulate Hh signals in the lower jaw. This study reveals a role for Boc in ventral CNS cells that receive high levels of Hh and uncovers previously unknown roles for Boc in vertebrate embryogenesis.
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Affiliation(s)
- Sadie A Bergeron
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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42
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nev (cyfip2) is required for retinal lamination and axon guidance in the zebrafish retinotectal system. Dev Biol 2010; 344:784-94. [PMID: 20537992 DOI: 10.1016/j.ydbio.2010.05.512] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Accepted: 05/26/2010] [Indexed: 11/23/2022]
Abstract
In the zebrafish retinotectal system, retinal ganglion cells (RGCs) project topographically along anterior-posterior (A-P) and dorsal-ventral (D-V) axes to innervate their primary target, the optic tectum. In the nevermind (nev) mutant, D-V positional information is not maintained by dorsonasal retinal axons as they project through the optic tract to the tectum. Here we present a detailed phenotypic analysis of the retinotectal projection in nev and show that dorsonasal axons do eventually find their correct location on the tectum, albeit after taking a circuitous path. Interestingly, nev seems to be specifically required for retinal axons but not for several non-retinal axon tracts. In addition, we find that nev is required both cell autonomously and cell nonautonomously for proper lamination of the retina. We show that nev encodes Cyfip2 (Cytoplasmic FMRP interacting protein 2) and is thus the first known mutation in a vertebrate Cyfip family member. Finally, we show that CYFIP2 acts cell autonomously in the D-V sorting of dorsonasal RGC axons in the optic tract. CYFIP2 is a highly conserved protein that lacks known domains or structural motifs but has been shown to interact with Rac and the fragile-X mental retardation protein, suggesting intriguing links to cytoskeletal dynamics and RNA regulation.
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43
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Ruthazer ES, Aizenman CD. Learning to see: patterned visual activity and the development of visual function. Trends Neurosci 2010; 33:183-92. [PMID: 20153060 DOI: 10.1016/j.tins.2010.01.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 01/08/2010] [Accepted: 01/14/2010] [Indexed: 11/17/2022]
Abstract
To successfully interact with their environments, developing organisms need to correctly process sensory information and generate motor outputs appropriate to their size and structure. Patterned sensory experience has long been known to induce various forms of developmental plasticity that ultimately shape mature neural circuits. These same types of plasticity also allow developing organisms to respond appropriately to the external world by dynamically adapting neural circuit function to ongoing changes in brain circuitry and sensory input. Recent work on the visual systems of frogs and fish has provided an unprecedented view into how visual experience dynamically affects circuit function at many levels, ranging from gene expression to network function, ultimately leading to system-wide functional adaptations.
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Affiliation(s)
- Edward S Ruthazer
- Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada.
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44
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Abstract
How neuronal connections are established during development is one of the most fascinating questions in the field of neurobiology. The zebrafish retinotectal system offers distinct advantages for studying axon guidance in an in vivo context. Its accessibility and the larva's transparency not only allow its direct visualization, but also facilitate experimental manipulations to address the mechanisms of its development. Here we describe methods for labeling and visualizing retinal axons in vivo, including transient expression of DNA constructs, injection of lipophilic dyes, and time-lapse imaging. We describe in detail the available transgenic lines for marking retinal ganglion cells (RGCs); a protocol for very precise lipophilic dye labeling; and a protocol for single cell electroporation of RGCs. We then describe several approaches for perturbing the retinotectal system, including morpholino or DNA injection; localized heat shock to induce misexpression of genes; a comprehensive list of known retinotectal mutants; and a detailed protocol for RGC transplants to test cell autonomy. These methods not only provide new ways for examining how retinal axons are guided by their environment, but also can be used to study other axonal tracts in the living embryo.
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45
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46
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Abstract
The zebrafish is one of the leading models for the analysis of the vertebrate visual system. A wide assortment of molecular, genetic, and cell biological approaches is available to study zebrafish visual system development and function. As new techniques become available, genetic analysis and imaging continue to be the strengths of the zebrafish model. In particular, recent developments in the use of transposons and zinc finger nucleases to produce new generations of mutant strains enhance both forward and reverse genetic analysis. Similarly, the imaging of developmental and physiological processes benefits from a wide assortment of fluorescent proteins and the ways to express them in the embryo. The zebrafish is also highly attractive for high-throughput screening of small molecules, a promising strategy to search for compounds with therapeutic potential. Here we discuss experimental approaches used in the zebrafish model to study morphogenetic transformations, cell fate decisions, and the differentiation of fine morphological features that ultimately lead to the formation of the functional vertebrate visual system.
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Affiliation(s)
- Andrei Avanesov
- Division of Craniofacial and Molecular Genetics, Tufts University, Boston, Massachusetts, USA
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47
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48
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Novel roles for collagens in wiring the vertebrate nervous system. Curr Opin Cell Biol 2008; 20:508-13. [DOI: 10.1016/j.ceb.2008.05.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 05/15/2008] [Accepted: 05/16/2008] [Indexed: 01/06/2023]
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49
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Gosse NJ, Nevin LM, Baier H. Retinotopic order in the absence of axon competition. Nature 2008; 452:892-5. [PMID: 18368050 DOI: 10.1038/nature06816] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Accepted: 02/04/2008] [Indexed: 11/09/2022]
Abstract
The retinotectal projection has long been studied experimentally and theoretically, as a model for the formation of topographic brain maps. Neighbouring retinal ganglion cells (RGCs) project their axons to neighbouring positions in the optic tectum, thus re-establishing a continuous neural representation of visual space. Mapping along this axis requires chemorepellent signalling from tectal cells, expressing ephrin-A ligands, to retinal growth cones, expressing EphA receptors. High concentrations of ephrin A, increasing from anterior to posterior, prevent temporal axons from invading the posterior tectum. However, the force that drives nasal axons to extend past the anterior tectum and terminate in posterior regions remains to be identified. We tested whether axon-axon interactions, such as competition, are required for posterior tectum innervation. By transplanting blastomeres from a wild-type (WT) zebrafish into a lakritz (lak) mutant, which lacks all RGCs, we created chimaeras with eyes that contained single RGCs. These solitary RGCs often extended axons into the tectum, where they branched to form a terminal arbor. Here we show that the distal tips of these arbors were positioned at retinotopically appropriate positions, ruling out an essential role for competition in innervation of the ephrin-A-rich posterior tectum. However, solitary arbors were larger and more complex than under normal, crowded conditions, owing to a lack of pruning of proximal branches during refinement of the retinotectal projection. We conclude that dense innervation is not required for targeting of retinal axons within the zebrafish tectum but serves to restrict arbor size and shape.
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Affiliation(s)
- Nathan J Gosse
- Program in Developmental Biology, University of California, San Francisco, Department of Physiology, 1550 Fourth Street, San Francisco, California 94158-2324, USA
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50
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Liu T, Li G, Nie J, Tarokh A, Zhou X, Guo L, Malicki J, Xia W, Wong STC. An automated method for cell detection in zebrafish. Neuroinformatics 2008; 6:5-21. [PMID: 18288618 DOI: 10.1007/s12021-007-9005-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 11/02/2007] [Indexed: 01/01/2023]
Abstract
Quantification of cells is a critical step towards the assessment of cell fate in neurological disease or developmental models. Here, we present a novel cell detection method for the automatic quantification of zebrafish neuronal cells, including primary motor neurons, Rohon-Beard neurons, and retinal cells. Our method consists of four steps. First, a diffused gradient vector field is produced. Subsequently, the orientations and magnitude information of diffused gradients are accumulated, and a response image is computed. In the third step, we perform non-maximum suppression on the response image and identify the detection candidates. In the fourth and final step the detected objects are grouped into clusters based on their color information. Using five different datasets depicting zebrafish cells, we show that our method consistently displays high sensitivity and specificity of over 95%. Our results demonstrate the general applicability of this method to different data samples, including nuclear staining, immunohistochemistry, and cell death detection.
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Affiliation(s)
- Tianming Liu
- The Center for Biomedical Informatics, The Methodist Hospital Research Institute, Houston, TX, USA
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