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Delia J, Gaines-Richardson M, Ludington SC, Akbari N, Vasek C, Shaykevich D, O’Connell LA. Tissue-specific in vivo transformation of plasmid DNA in Neotropical tadpoles using electroporation. PLoS One 2023; 18:e0289361. [PMID: 37590232 PMCID: PMC10434853 DOI: 10.1371/journal.pone.0289361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 07/11/2023] [Indexed: 08/19/2023] Open
Abstract
Electroporation is an increasingly common technique used for exogenous gene expression in live animals, but protocols are largely limited to traditional laboratory organisms. The goal of this protocol is to test in vivo electroporation techniques in a diverse array of tadpole species. We explore electroporation efficiency in tissue-specific cells of five species from across three families of tropical frogs: poison frogs (Dendrobatidae), cryptic forest/poison frogs (Aromobatidae), and glassfrogs (Centrolenidae). These species are well known for their diverse social behaviors and intriguing physiologies that coordinate chemical defenses, aposematism, and/or tissue transparency. Specifically, we examine the effects of electrical pulse and injection parameters on species- and tissue-specific transfection of plasmid DNA in tadpoles. After electroporation of a plasmid encoding green fluorescent protein (GFP), we found strong GFP fluorescence within brain and muscle cells that increased with the amount of DNA injected and electrical pulse number. We discuss species-related challenges, troubleshooting, and outline ideas for improvement. Extending in vivo electroporation to non-model amphibian species could provide new opportunities for exploring topics in genetics, behavior, and organismal biology.
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Affiliation(s)
- Jesse Delia
- Department of Biology, Stanford University, Stanford, CA, United States of America
| | | | - Sarah C. Ludington
- Department of Biology, Stanford University, Stanford, CA, United States of America
| | - Najva Akbari
- Department of Biology, Stanford University, Stanford, CA, United States of America
| | - Cooper Vasek
- Department of Biology, De Anza College, Cupertino, CA, United States of America
| | - Daniel Shaykevich
- Department of Biology, Stanford University, Stanford, CA, United States of America
| | - Lauren A. O’Connell
- Department of Biology, Stanford University, Stanford, CA, United States of America
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2
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Jacobs IV EJ, Graybill PM, Jana A, Agashe A, Nain AS, Davalos RV. Engineering high post-electroporation viabilities and transfection efficiencies for elongated cells on suspended nanofiber networks. Bioelectrochemistry 2023; 152:108415. [PMID: 37011476 DOI: 10.1016/j.bioelechem.2023.108415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 02/14/2023] [Accepted: 03/12/2023] [Indexed: 04/03/2023]
Abstract
The impact of cell shape on cell membrane permeabilization by pulsed electric fields is not fully understood. For certain applications, cell survival and recovery post-treatment is either desirable, as in gene transfection, electrofusion, and electrochemotherapy, or is undesirable, as in tumor and cardiac ablations. Understanding of how morphology affects cell viability post-electroporation may lead to improved electroporation methods. In this study, we use precisely aligned nanofiber networks within a microfluidic device to reproducibly generate elongated cells with controlled orientations to an applied electric field. We show that cell viability is significantly dependent on cell orientation, elongation, and spread. Further, these trends are dependent on the external buffer conductivity. Additionally, we see that cell survival for elongated cells is still supported by the standard pore model of electroporation. Lastly, we see that manipulating the cell orientation and shape can be leveraged for increased transfection efficiencies when compared to spherical cells. An improved understanding of cell shape and pulsation buffer conductivity may lead to improved methods for enhancing cell viability post-electroporation by engineering the cell morphology, cytoskeleton, and electroporation buffer conditions.
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3
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Day-Cooney J, Dalangin R, Zhong H, Mao T. Genetically encoded fluorescent sensors for imaging neuronal dynamics in vivo. J Neurochem 2023; 164:284-308. [PMID: 35285522 DOI: 10.1111/jnc.15608] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/14/2022] [Accepted: 02/25/2022] [Indexed: 11/29/2022]
Abstract
The brain relies on many forms of dynamic activities in individual neurons, from synaptic transmission to electrical activity and intracellular signaling events. Monitoring these neuronal activities with high spatiotemporal resolution in the context of animal behavior is a necessary step to achieve a mechanistic understanding of brain function. With the rapid development and dissemination of highly optimized genetically encoded fluorescent sensors, a growing number of brain activities can now be visualized in vivo. To date, cellular calcium imaging, which has been largely used as a proxy for electrical activity, has become a mainstay in systems neuroscience. While challenges remain, voltage imaging of neural populations is now possible. In addition, it is becoming increasingly practical to image over half a dozen neurotransmitters, as well as certain intracellular signaling and metabolic activities. These new capabilities enable neuroscientists to test previously unattainable hypotheses and questions. This review summarizes recent progress in the development and delivery of genetically encoded fluorescent sensors, and highlights example applications in the context of in vivo imaging.
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Affiliation(s)
- Julian Day-Cooney
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Rochelin Dalangin
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, California, USA
| | - Haining Zhong
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Tianyi Mao
- Vollum Institute, Oregon Health and Science University, Portland, Oregon, USA
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4
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Huang R, Xu Y, Chen M, Yang L, Wang X, Shen Y, Huang Y, Hu B. Visualizing the Intracellular Trafficking in Zebrafish Mauthner Cells. Methods Mol Biol 2022; 2431:351-364. [PMID: 35412286 DOI: 10.1007/978-1-0716-1990-2_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Axonal transport is crucial for the development and survival of neurons and maintenance of neuronal function. Disruption in this active process causes diverse neurological diseases. Thus, study of the intracellular trafficking as one way to gain the knowledge of the kinetics of axonal transport is essential to understand the mechanisms underlying the neuropathology. A lot of studies have been completed in vitro with neuron cultures and tissues, which may not accurately replicate the in vivo situation. Therefore, intravital manipulations are essential to achieve this goal. Here we introduce a technique that has been widely used in our lab to study the cargo trafficking in zebrafish at single-cell resolution. We use mitochondria as a representative neuronal cargo and provide step-by-step instructions on how to label specific cargoes within zebrafish Mauthner cells. This method can also be expanded to study the kinetics of other cargoes as well as the role of molecular regulators in axonal transport.
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Affiliation(s)
- Rongchen Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Yang Xu
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Min Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Leiqing Yang
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Xinliang Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Yueru Shen
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Yubin Huang
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China
| | - Bing Hu
- Hefei National Laboratory for Physical Sciences at the Microscale, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, P.R. China.
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5
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Pandey P, Sesena-Rubfiaro A, Khatri S, He J. Development of multifunctional nanopipettes for controlled intracellular delivery and single-entity detection. Faraday Discuss 2021; 233:315-335. [PMID: 34889345 DOI: 10.1039/d1fd00057h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The intracellular delivery of biomolecules and nanoscale materials to individual cells has gained remarkable attention in recent years owing to its wide applications in drug delivery, clinical diagnostics, bio-imaging and single-cell analysis. It remains a challenge to control and measure the delivered amount in one cell. In this work, we developed a multifunctional nanopipette - containing both a nanopore and nanoelectrode (pyrolytic carbon) at the apex - as a facile, minimally invasive and effective platform for both controllable single-cell intracellular delivery and single-entity counting. While controlled by a micromanipulator, the baseline changes of the nanopore ionic current (I) and nanoelectrode open circuit potential (V) help to guide the nanopipette tip insertion and positioning processes. The delivery from the nanopore barrel can be facilely controlled by the applied nanopore bias. To optimize the intracellular single-entity detection during delivery, we studied the effects of the nanopipette tip geometry and solution salt concentration in controlled experiments. We have successfully delivered gold nanoparticles and biomolecules into the cell, as confirmed by the increased scattering and fluorescence signals, respectively. The delivered entities have also been detected at the single-entity level using either one or both transient I and V signals. We found that the sensitivity of the single-entity electrochemical measurement was greatly affected by the local environment of the cell and varied between cell lines.
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Affiliation(s)
- Popular Pandey
- Physics Department, Florida International University, Miami, Florida, 33199, USA.
| | | | - Santosh Khatri
- Physics Department, Florida International University, Miami, Florida, 33199, USA.
| | - Jin He
- Physics Department, Florida International University, Miami, Florida, 33199, USA. .,Biomolecular Sciences Institute, Florida International University, Miami, Florida, 33199, USA
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Cline HT. Imaging Structural and Functional Dynamics in Xenopus Neurons. Cold Spring Harb Protoc 2021; 2022:pdb.top106773. [PMID: 34531329 DOI: 10.1101/pdb.top106773] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In vivo time-lapse imaging has been a fruitful approach to identify structural and functional changes in the Xenopus nervous system in tadpoles and adult frogs. Structural imaging studies have identified fundamental aspects of brain connectivity, development, plasticity, and disease and have been instrumental in elucidating mechanisms regulating these events in vivo. Similarly, assessment of nervous system function using dynamic changes in calcium signals as a proxy for neuronal activity has demonstrated principles of neuron and circuit function and principles of information organization and transfer within the brain of living animals. Because of its many advantages as an experimental system, use of Xenopus has often been at the forefront of developing these imaging methods for in vivo applications. Protocols for in vivo structural and functional imaging-including cellular labeling strategies, image collection, and image analysis-will expand the use of Xenopus to understand brain development, function, and plasticity.
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Affiliation(s)
- Hollis T Cline
- Department of Neuroscience, Dorris Neuroscience Center, The Scripps Research Center, La Jolla, California 92039, USA
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Slater PG, Palacios M, Larraín J. Xenopus, a Model to Study Wound Healing and Regeneration: Experimental Approaches. Cold Spring Harb Protoc 2021; 2021:pdb.top100966. [PMID: 33782095 DOI: 10.1101/pdb.top100966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Xenopus has been widely used as a model organism to study wound healing and regeneration. During early development and at tadpole stages, Xenopus is a quick healer and is able to regenerate multiple complex organs-abilities that decrease with the progression of metamorphosis. This unique capacity leads us to question which mechanisms allow and direct regeneration at stages before the beginning of metamorphosis and which ones are responsible for the loss of regenerative capacities during later stages. Xenopus is an ideal model to study regeneration and has contributed to the understanding of morphological, cellular, and molecular mechanisms involved in these processes. Nevertheless, there is still much to learn. Here we provide an overview on using Xenopus as a model organism to study regeneration and introduce protocols that can be used for studying wound healing and regeneration at multiple levels, thus enhancing our understanding of these phenomena.
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Affiliation(s)
- Paula G Slater
- Center for Aging and Regeneration, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago de Chile, Chile 7820436
| | - Miriam Palacios
- Center for Aging and Regeneration, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago de Chile, Chile 7820436
| | - Juan Larraín
- Center for Aging and Regeneration, Facultad de Ciencias Biológicas, P. Universidad Católica de Chile, Santiago de Chile, Chile 7820436
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8
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Gore SV, James EJ, Huang LC, Park JJ, Berghella A, Thompson AC, Cline HT, Aizenman CD. Role of matrix metalloproteinase-9 in neurodevelopmental deficits and experience-dependent plasticity in Xenopus laevis. eLife 2021; 10:62147. [PMID: 34282726 PMCID: PMC8315794 DOI: 10.7554/elife.62147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 07/18/2021] [Indexed: 02/06/2023] Open
Abstract
Matrix metalloproteinase-9 (MMP-9) is a secreted endopeptidase targeting extracellular matrix proteins, creating permissive environments for neuronal development and plasticity. Developmental dysregulation of MMP-9 may also lead to neurodevelopmental disorders (ND). Here, we test the hypothesis that chronically elevated MMP-9 activity during early neurodevelopment is responsible for neural circuit hyperconnectivity observed in Xenopus tadpoles after early exposure to valproic acid (VPA), a known teratogen associated with ND in humans. In Xenopus tadpoles, VPA exposure results in excess local synaptic connectivity, disrupted social behavior and increased seizure susceptibility. We found that overexpressing MMP-9 in the brain copies effects of VPA on synaptic connectivity, and blocking MMP-9 activity pharmacologically or genetically reverses effects of VPA on physiology and behavior. We further show that during normal neurodevelopment MMP-9 levels are tightly regulated by neuronal activity and required for structural plasticity. These studies show a critical role for MMP-9 in both normal and abnormal development.
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Affiliation(s)
- Sayali V Gore
- Department of Neuroscience, Brown University, Providence, United States
| | - Eric J James
- Department of Neuroscience, Brown University, Providence, United States
| | | | - Jenn J Park
- Department of Neuroscience, Brown University, Providence, United States
| | - Andrea Berghella
- Department of Neuroscience, Brown University, Providence, United States
| | - Adrian C Thompson
- Department of Neuroscience, Brown University, Providence, United States
| | | | - Carlos D Aizenman
- Department of Neuroscience, Brown University, Providence, United States
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9
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Faulkner RL, Wall NR, Callaway EM, Cline HT. Application of Recombinant Rabies Virus to Xenopus Tadpole Brain. eNeuro 2021; 8:ENEURO.0477-20.2021. [PMID: 34099488 PMCID: PMC8260272 DOI: 10.1523/eneuro.0477-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 05/13/2021] [Accepted: 05/31/2021] [Indexed: 12/25/2022] Open
Abstract
The Xenopus laevis experimental system has provided significant insight into the development and plasticity of neural circuits. Xenopus neuroscience research would be enhanced by additional tools to study neural circuit structure and function. Rabies viruses are powerful tools to label and manipulate neural circuits and have been widely used to study mesoscale connectomics. Whether rabies virus can be used to transduce neurons and express transgenes in Xenopus has not been systematically investigated. Glycoprotein-deleted rabies virus transduces neurons at the axon terminal and retrogradely labels their cell bodies. We show that glycoprotein-deleted rabies virus infects local and projection neurons in the Xenopus tadpole when directly injected into brain tissue. Pseudotyping glycoprotein-deleted rabies with EnvA restricts infection to cells with exogenous expression of the EnvA receptor, TVA. EnvA pseudotyped virus specifically infects tadpole neurons with promoter-driven expression of TVA, demonstrating its utility to label targeted neuronal populations. Neuronal cell types are defined by a combination of features including anatomical location, expression of genetic markers, axon projection sites, morphology, and physiological properties. We show that driving TVA expression in one hemisphere and injecting EnvA pseudotyped virus into the contralateral hemisphere, retrogradely labels neurons defined by cell body location and axon projection site. Using this approach, rabies can be used to identify cell types in Xenopus brain and simultaneously to express transgenes which enable monitoring or manipulation of neuronal activity. This makes rabies a valuable tool to study the structure and function of neural circuits in Xenopus.Significance StatementStudies in Xenopus have contributed a great deal to our understanding of brain circuit development and plasticity, regeneration, and hormonal regulation of behavior and metamorphosis. Here, we show that recombinant rabies virus transduces neurons in the Xenopus tadpole, enlarging the toolbox that can be applied to studying Xenopus brain. Rabies can be used for retrograde labeling and expression of a broad range of transgenes including fluorescent proteins for anatomical tracing and studying neuronal morphology, voltage or calcium indicators to visualize neuronal activity, and photo- or chemosensitive channels to control neuronal activity. The versatility of these tools enables diverse experiments to analyze and manipulate Xenopus brain structure and function, including mesoscale connectivity.
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Affiliation(s)
- Regina L Faulkner
- Neuroscience Department and The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla CA
| | | | | | - Hollis T Cline
- Neuroscience Department and The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla CA
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10
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Morshedi Rad D, Alsadat Rad M, Razavi Bazaz S, Kashaninejad N, Jin D, Ebrahimi Warkiani M. A Comprehensive Review on Intracellular Delivery. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005363. [PMID: 33594744 DOI: 10.1002/adma.202005363] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/22/2020] [Indexed: 05/22/2023]
Abstract
Intracellular delivery is considered an indispensable process for various studies, ranging from medical applications (cell-based therapy) to fundamental (genome-editing) and industrial (biomanufacture) approaches. Conventional macroscale delivery systems critically suffer from such issues as low cell viability, cytotoxicity, and inconsistent material delivery, which have opened up an interest in the development of more efficient intracellular delivery systems. In line with the advances in microfluidics and nanotechnology, intracellular delivery based on micro- and nanoengineered platforms has progressed rapidly and held great promises owing to their unique features. These approaches have been advanced to introduce a smorgasbord of diverse cargoes into various cell types with the maximum efficiency and the highest precision. This review differentiates macro-, micro-, and nanoengineered approaches for intracellular delivery. The macroengineered delivery platforms are first summarized and then each method is categorized based on whether it employs a carrier- or membrane-disruption-mediated mechanism to load cargoes inside the cells. Second, particular emphasis is placed on the micro- and nanoengineered advances in the delivery of biomolecules inside the cells. Furthermore, the applications and challenges of the established and emerging delivery approaches are summarized. The topic is concluded by evaluating the future perspective of intracellular delivery toward the micro- and nanoengineered approaches.
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Affiliation(s)
- Dorsa Morshedi Rad
- School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Maryam Alsadat Rad
- School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Sajad Razavi Bazaz
- School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Navid Kashaninejad
- School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Dayong Jin
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
- School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Majid Ebrahimi Warkiani
- School of Biomedical Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, NSW, 2007, Australia
- Institute of Molecular Medicine, Sechenov University, Moscow, 119991, Russia
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11
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He HY, Lin CY, Cline HT. In Vivo Time-Lapse Imaging and Analysis of Dendritic Structural Plasticity in Xenopus laevis Tadpoles. Cold Spring Harb Protoc 2021; 2022:pdb.prot106781. [PMID: 33790043 DOI: 10.1101/pdb.prot106781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In vivo time-lapse imaging of complete dendritic arbor structures in tectal neurons of Xenopus laevis tadpoles has served as a powerful in vivo model to study activity-dependent structural plasticity in the central nervous system during early development. In addition to quantitative analysis of gross arbor structure, dynamic analysis of the four-dimensional data offers particularly valuable insights into the structural changes occurring in subcellular domains over experience/development-driven structural plasticity events. Such analysis allows not only quantifiable characterization of branch additions and retractions with high temporal resolution but also identification of the loci of action. This allows for a better understanding of the spatiotemporal association of structural changes to functional relevance. Here we describe a protocol for in vivo time-lapse imaging of complete dendritic arbors from individual neurons in the brains of anesthetized tadpoles with two-photon microscopy and data analysis of the time series of 3D dendritic arbors. For data analysis, we focus on dynamic analysis of reconstructed neuronal filaments using a customized open source computer program we developed (4D SPA), which allows aligning and matching of 3D neuronal structures across different time points with greatly improved speed and reliability. File converters are provided to convert reconstructed filament files from commercial reconstruction software to be used in 4D SPA. The program and user manual are publicly accessible and operate through a graphical user interface on both Windows and Mac OSX.
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Affiliation(s)
- Hai-Yan He
- Department of Biology, Georgetown University, Washington, D.C. 20057, USA
| | - Chih-Yang Lin
- Department of Optoelectronics and Materials Engineering, Chung Hua University, Hsinchu 30012, Taiwan
| | - Hollis T Cline
- Neuroscience Department, Dorris Neuroscience Center, Scripps Research Institute, La Jolla, California 92037, USA
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12
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Hiramoto M, Cline HT. Precisely controlled visual stimulation to study experience-dependent neural plasticity in Xenopus tadpoles. STAR Protoc 2021; 2:100252. [PMID: 33490972 PMCID: PMC7809435 DOI: 10.1016/j.xpro.2020.100252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Studies on visual experience-dependent plasticity can benefit tremendously from experimental protocols in which sensory stimulation is precisely controlled for extended periods over which neuronal, circuit, and behavioral plasticity occurs. Small vertebrates, such as Xenopus tadpoles and zebrafish, are excellent systems for studying brain plasticity. Here, we present a detailed protocol to perform controlled visual stimulation for extended time periods. These methods have been used to study structural plasticity induced by temporally controlled visual stimulation in Xenopus tadpoles. For further details on the use and execution of this protocol, please refer to Hiramoto and Cline (2014, 2020). A detailed protocol to immobilize live tadpoles over 10–12 h Strategies to evoke reproducible visual responses in the retinal ganglion cells Design of devices for visual stimulation Minimally invasive, efficient electroporation of the retinal ganglion cells
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Affiliation(s)
- Masaki Hiramoto
- The Scripps Research Institute, The Dorris Neuroscience Center, 10550 N. Torrey Pines Rd., San Diego, CA 92037, USA
| | - Hollis T Cline
- The Scripps Research Institute, The Dorris Neuroscience Center, 10550 N. Torrey Pines Rd., San Diego, CA 92037, USA
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Abstract
The ability to microinject substances into the cytosol of living neutrophils opens the possibility of manipulating the chemistry within the cell and also of monitoring changes using indicators which otherwise cannot be introduced into the cell. However, neutrophils cannot be microinjected by the conventional glass pipette insertion method. Here we outline two techniques which work well with neutrophils, namely, SLAM (Simple Lipid-Assisted Microinjection) and electromicroinjection. As these methods utilize micropipettes, we also include a simple method which uses a micropipette to deliver a phagocytic stimulus to a specific cell at a defined time, enable detailed study of the phagocytic process from particle contact to particle internalization.
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14
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Schohl A, Chorghay Z, Ruthazer ES. A Simple and Efficient Method for Visualizing Individual Cells in vivo by Cre-Mediated Single-Cell Labeling by Electroporation (CREMSCLE). Front Neural Circuits 2020; 14:47. [PMID: 32848634 PMCID: PMC7399061 DOI: 10.3389/fncir.2020.00047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/08/2020] [Indexed: 11/13/2022] Open
Abstract
Efficient methods for visualizing cell morphology in the intact animal are of great benefit to the study of structural development in the nervous system. Quantitative analysis of the complex arborization patterns of brain cells informs cell-type classification, dissection of neuronal circuit wiring, and the elucidation of growth and plasticity mechanisms. Time-lapse single-cell morphological analysis requires labeling and imaging of single cells in situ without contamination from the ramified processes of other nearby cells. Here, using the Xenopus laevis optic tectum as a model system, we describe CRE-Mediated Single-Cell Labeling by Electroporation (CREMSCLE), a technique we developed based on bulk co-electroporation of Cre-dependent inducible expression vectors, together with very low concentrations of plasmid encoding Cre recombinase. This method offers efficient, sparse labeling in any brain area where bulk electroporation is possible. Unlike juxtacellular single-cell electroporation methods, CREMSCLE relies exclusively on the bulk electroporation technique, circumventing the need to precisely position a micropipette next to the target cell. Compared with viral transduction methods, it is fast and safe, generating high levels of expression within 24 h of introducing non-infectious plasmid DNA. In addition to increased efficiency of single-cell labeling, we confirm that CREMSCLE also allows for efficient co-expression of multiple gene products in the same cell. Furthermore, we demonstrate that this method is particularly well-suited for labeling immature neurons to follow their maturation over time. This approach therefore lends itself well to time-lapse morphological studies, particularly in the context of early neuronal development and under conditions that prevent more difficult visualized juxtacellular electroporation.
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Affiliation(s)
- Anne Schohl
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
| | - Zahraa Chorghay
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
| | - Edward S Ruthazer
- Department of Neurology and Neurosurgery, Montreal Neurological Institute-Hospital, McGill University, Montreal, QC, Canada
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15
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Graybill PM, Davalos RV. Cytoskeletal Disruption after Electroporation and Its Significance to Pulsed Electric Field Therapies. Cancers (Basel) 2020; 12:E1132. [PMID: 32366043 PMCID: PMC7281591 DOI: 10.3390/cancers12051132] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/18/2022] Open
Abstract
Pulsed electric fields (PEFs) have become clinically important through the success of Irreversible Electroporation (IRE), Electrochemotherapy (ECT), and nanosecond PEFs (nsPEFs) for the treatment of tumors. PEFs increase the permeability of cell membranes, a phenomenon known as electroporation. In addition to well-known membrane effects, PEFs can cause profound cytoskeletal disruption. In this review, we summarize the current understanding of cytoskeletal disruption after PEFs. Compiling available studies, we describe PEF-induced cytoskeletal disruption and possible mechanisms of disruption. Additionally, we consider how cytoskeletal alterations contribute to cell-cell and cell-substrate disruption. We conclude with a discussion of cytoskeletal disruption-induced anti-vascular effects of PEFs and consider how a better understanding of cytoskeletal disruption after PEFs may lead to more effective therapies.
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Affiliation(s)
- Philip M. Graybill
- BEMS Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA;
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Rafael V. Davalos
- BEMS Lab, Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA;
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
- Virginia Tech–Wake Forest University, School of Biomedical Engineering and Sciences, Blacksburg, VA 24061, USA
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16
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Abstract
Antisense morpholino oligonucleotides (MOs) have become a valuable method to knockdown protein levels, to block with mRNA splicing and to interfere with miRNA function. MOs are widely used to alter gene expression in development of Xenopus and Zebrafish, where they are typically injected into the fertilized egg or blastomeres. Here we present methods to use electroporation to target delivery of MOs to the central nervous system of Xenopus laevis or Xenopus tropicalis tadpoles. Briefly, MO electroporation is accomplished by injecting MO solution into the brain ventricle and driving the MOs into cells of the brain with current passing between 2 platinum plate electrodes, positioned on either side of the target brain area. The method is relatively straightforward and uses standard equipment found in many neuroscience labs. A major advantage of electroporation is that it allows spatial and temporal control of MO delivery and therefore knockdown. Co-electroporation of MOs with cell type-specific fluorescent protein expression plasmids allows morphological analysis of cellular phenotypes. Furthermore, co-electroporation of MOs with rescuing plasmids allows assessment of specificity of the knockdown and phenotypic outcome. By combining MO-mediated manipulations with sophisticated assays of neuronal function, such as electrophysiological recording, behavioral assays, or in vivo time-lapse imaging of neuronal development, the functions of specific proteins and miRNAs within the developing nervous system can be elucidated. These methods can be adapted to apply antisense morpholinos to study protein and RNA function in a variety of complex tissues.
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Affiliation(s)
| | - Hollis T Cline
- The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA.
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17
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Kuramoto E. Method for labeling and reconstruction of single neurons using Sindbis virus vectors. J Chem Neuroanat 2019; 100:101648. [PMID: 31181303 DOI: 10.1016/j.jchemneu.2019.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/11/2019] [Accepted: 05/08/2019] [Indexed: 10/26/2022]
Abstract
Neuronal dendrites and axons are key substrates for the input and output of information, respectively, so establishing the precise and complete morphological description of dendritic and axonal processes of a single neuron is essential for understanding the neuron's functional role in the neuronal circuits. The whole structure of single neurons was originally revealed using Golgi staining, and later the intracellular labeling method was developed, although this is technically too difficult to stain entire neurons in vivo. Since the late 1980s, molecular biology techniques have been applied to neuroscience research, leading to the development of various virus vectors, such as the Sindbis and adeno-associated virus vectors, which have facilitated the reconstruction of neurons at a single cell level. In the present review, we focus on a method for labeling and reconstruction of single neurons using Sindbis virus vectors that express membrane-targeted fluorescent proteins. We describe in detail a protocol for single-neuron labeling using Sindbis virus vectors, and we provide an example of a recent project at our laboratory in which we successfully applied these methods to study thalamocortical projection neurons. Further, we discuss the strengths and limitations of Sindbis virus vectors for single neuron reconstruction, comparing them with adeno-associated virus vectors.
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Affiliation(s)
- Eriko Kuramoto
- Department of Oral Anatomy and Cell Biology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan.
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18
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Weiss L, Offner T, Hassenklöver T, Manzini I. Dye Electroporation and Imaging of Calcium Signaling in Xenopus Nervous System. Methods Mol Biol 2018; 1865:217-231. [PMID: 30151769 DOI: 10.1007/978-1-4939-8784-9_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Electroporation is an efficient method of transferring charged macromolecules into living cells in order to study their morphology, function, and connectivity within neuronal networks. Labeling cells with fluorophore-coupled macromolecules can be used to trace projections of whole neuronal ensembles, as well as the fine morphology of single cells. Here, we present a protocol to visualize pre- and postsynaptic components of a sensory relay synapse in the brain, using the olfactory system of Xenopus laevis tadpoles as a model. We apply bulk electroporation to trace projections of receptor neurons from the nose to the brain, and single cell electroporation to visualize the morphology of their synaptic target cells, the mitral-tufted cells. Labeling the receptor neurons with a calcium-sensitive dye allows us to record stimulus-induced presynaptic input to the dendrites of the postsynaptic cells via functional calcium imaging.
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Affiliation(s)
- Lukas Weiss
- Department of Animal Physiology and Molecular Biomedicine, Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Thomas Offner
- Department of Animal Physiology and Molecular Biomedicine, Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany.,Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Thomas Hassenklöver
- Department of Animal Physiology and Molecular Biomedicine, Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Ivan Manzini
- Department of Animal Physiology and Molecular Biomedicine, Institute of Animal Physiology, Justus-Liebig-University Giessen, Giessen, Germany. .,Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany.
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19
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A robot for high yield electrophysiology and morphology of single neurons in vivo. Nat Commun 2017; 8:15604. [PMID: 28569837 PMCID: PMC5461495 DOI: 10.1038/ncomms15604] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 04/06/2017] [Indexed: 01/13/2023] Open
Abstract
Single-cell characterization and perturbation of neurons provides knowledge critical to addressing fundamental neuroscience questions including the structure–function relationship and neuronal cell-type classification. Here we report a robot for efficiently performing in vivo single-cell experiments in deep brain tissues optically difficult to access. This robot automates blind (non-visually guided) single-cell electroporation (SCE) and extracellular electrophysiology, and can be used to characterize neuronal morphological and physiological properties of, and/or manipulate genetic/chemical contents via delivering extraneous materials (for example, genes) into single neurons in vivo. Tested in the mouse brain, our robot successfully reveals the full morphology of single-infragranular neurons recorded in multiple neocortical regions, as well as deep brain structures such as hippocampal CA3, with high efficiency. Our robot thus can greatly facilitate the study of in vivo full morphology and electrophysiology of single neurons in the brain. Single-cell characterization and perturbation of neurons is critical for revealing the structure-function relationship of brain cells. Here the authors develop a robot that performs single-cell electroporation and extracellular electrophysiology and can be used for performing in vivo single-cell experiments in deep brain tissues optically difficult to access.
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20
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Slater PG, Hayrapetian L, Lowery LA. Xenopus laevis as a model system to study cytoskeletal dynamics during axon pathfinding. Genesis 2017; 55. [PMID: 28095612 DOI: 10.1002/dvg.22994] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 11/02/2016] [Accepted: 11/04/2016] [Indexed: 01/17/2023]
Abstract
The model system, Xenopus laevis, has been used in innumerable research studies and has contributed to the understanding of multiple cytoskeletal components, including actin, microtubules, and neurofilaments, during axon pathfinding. Xenopus developmental stages have been widely characterized, and the Xenopus genome has been sequenced, allowing gene expression modifications through exogenous molecules. Xenopus cell cultures are ideal for long periods of live imaging because they are easily obtained and maintained, and they do not require special culture conditions. In addition, Xenopus have relatively large growth cones, compared to other vertebrates, thus providing a suitable system for imaging cytoskeletal components. Therefore, X. laevis is an ideal model organism in which to study cytoskeletal dynamics during axon pathfinding.
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Affiliation(s)
- Paula G Slater
- Department of Biology, Boston College, Chestnut Hill, Massachusetts
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21
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Investigation of ac-magnetic field stimulated nanoelectroporation of magneto-electric nano-drug-carrier inside CNS cells. Sci Rep 2017; 7:45663. [PMID: 28374799 PMCID: PMC5379488 DOI: 10.1038/srep45663] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/02/2017] [Indexed: 12/17/2022] Open
Abstract
In this research, we demonstrate cell uptake of magneto-electric nanoparticles (MENPs) through nanoelectroporation (NEP) using alternating current (ac)-magnetic field stimulation. Uptake of MENPs was confirmed using focused-ion-beam assisted transmission electron microscopy (FIB-TEM) and validated by a numerical simulation model. The NEP was performed in microglial (MG) brain cells, which are highly sensitive for neuro-viral infection and were selected as target for nano-neuro-therapeutics. When the ac-magnetic field optimized (60 Oe at 1 kHz), MENPs were taken up by MG cells without affecting cell health (viability > 92%). FIB-TEM analysis of porated MG cells confirmed the non-agglomerated distribution of MENPs inside the cell and no loss of their elemental and crystalline characteristics. The presented NEP method can be adopted as a part of future nanotherapeutics and nanoneurosurgery strategies where a high uptake of a nanomedicine is required for effective and timely treatment of brain diseases.
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22
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Xu Y, Chen M, Hu B, Huang R, Hu B. In vivo Imaging of Mitochondrial Transport in Single-Axon Regeneration of Zebrafish Mauthner Cells. Front Cell Neurosci 2017; 11:4. [PMID: 28174522 PMCID: PMC5258718 DOI: 10.3389/fncel.2017.00004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial transport is essential for neuronal function, but the evidence of connections between mitochondrial transport and axon regeneration in the central nervous system (CNS) of living vertebrates remains limited. Here, we developed a novel model to explore mitochondrial transport in a single Mauthner axon (M axon) of zebrafish with non-invasive in vivo imaging. To confirm the feasibility of using this model, we treated labeled zebrafish with nocodazole and demonstrated that it could disrupt mitochondrial transport. We also used two-photon laser axotomy to precisely axotomize M axons and simultaneously recorded their regeneration and the process of mitochondrial transport in living zebrafish larvae. The findings showed that the injured axons with stronger regenerative capability maintain greater mitochondrial motility. Furthermore, to stimulate axon regeneration, treatment with dibutyryl cyclic adenosine monophosphate (db-cAMP) could also augment mitochondrial motility. Taken together, our results provide new evidence that mitochondrial motility is positively correlated with axon regeneration in the living vertebrate CNS. This promising model will be useful for further studies on the interaction between axon regeneration and mitochondrial dynamics, using various genetic and pharmacological techniques.
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Affiliation(s)
- Yang Xu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Min Chen
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bingbing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Rongchen Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
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23
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Edwards-Faret G, Muñoz R, Méndez-Olivos EE, Lee-Liu D, Tapia VS, Larraín J. Spinal cord regeneration in Xenopus laevis. Nat Protoc 2017; 12:372-389. [PMID: 28102835 DOI: 10.1038/nprot.2016.177] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Here we present a protocol for the husbandry of Xenopus laevis tadpoles and froglets, and procedures to study spinal cord regeneration. This includes methods to induce spinal cord injury (SCI); DNA and morpholino electroporation for genetic studies; in vivo imaging for cell analysis; a swimming test to measure functional recovery; and a convenient model for screening for new compounds that promote neural regeneration. These protocols establish X. laevis as a unique model organism for understanding spinal cord regeneration by comparing regenerative and nonregenerative stages. This protocol can be used to understand the molecular and cellular mechanisms involved in nervous system regeneration, including neural stem and progenitor cell (NSPC) proliferation and neurogenesis, extrinsic and intrinsic mechanisms involved in axon regeneration, glial response and scar formation, and trophic factors. For experienced personnel, husbandry takes 1-2 months; SCI can be achieved in 5-15 min; and swimming recovery takes 20-30 d.
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Affiliation(s)
- Gabriela Edwards-Faret
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Rosana Muñoz
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Emilio E Méndez-Olivos
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Dasfne Lee-Liu
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Victor S Tapia
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Larraín
- Center for Aging and Regeneration, Millennium Nucleus in Regenerative Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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24
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Abstract
Myelination by oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system is essential for nervous system function and health. Despite its importance, we have a relatively poor understanding of the molecular and cellular mechanisms that regulate myelination in the living animal, particularly in the CNS. This is partly due to the fact that myelination commences around birth in mammals, by which time the CNS is complex and largely inaccessible, and thus very difficult to image live in its intact form. As a consequence, in recent years much effort has been invested in the use of smaller, simpler, transparent model organisms to investigate mechanisms of myelination in vivo. Although the majority of such studies have employed zebrafish, the Xenopus tadpole also represents an important complementary system with advantages for investigating myelin biology in vivo. Here we review how the natural features of zebrafish embryos and larvae and Xenopus tadpoles make them ideal systems for experimentally interrogating myelination by live imaging. We outline common transgenic technologies used to generate zebrafish and Xenopus that express fluorescent reporters, which can be used to image myelination. We also provide an extensive overview of the imaging modalities most commonly employed to date to image the nervous system in these transparent systems, and also emerging technologies that we anticipate will become widely used in studies of zebrafish and Xenopus myelination in the near future.
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Affiliation(s)
- Jenea M Bin
- Centre for Neuroregeneration, MS Society Centre for Translational Research, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
| | - David A Lyons
- Centre for Neuroregeneration, MS Society Centre for Translational Research, Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, UK
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25
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Olfactory experiences dynamically regulate plasticity of dendritic spines in granule cells of Xenopus tadpoles in vivo. Sci Rep 2016; 6:35009. [PMID: 27713557 PMCID: PMC5054522 DOI: 10.1038/srep35009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 09/22/2016] [Indexed: 11/08/2022] Open
Abstract
Granule cells, rich in dendrites with densely punctated dendritic spines, are the most abundant inhibitory interneurons in the olfactory bulb. The dendritic spines of granule cells undergo remodeling during the development of the nervous system. The morphological plasticity of the spines' response to different olfactory experiences in vivo is not fully known. In initial studies, a single granule cell in Xenopus tadpoles was labeled with GFP plasmids via cell electroporation; then, morphologic changes of the granule cell spines were visualized by in vivo confocal time-lapse imaging. With the help of long-term imaging, the total spine density, dynamics, and stability of four types of dendritic spines (mushroom, stubby, thin and filopodia) were obtained. Morphological analysis demonstrated that odor enrichment produced a remarkable increase in the spine density and stability of large mushroom spine. Then, with the help of short-term imaging, we analyzed the morphological transitions among different spines. We found that transitions between small spines (thin and filopodia) were more easily influenced by odor stimulation or olfactory deprivation. These results indicate that different olfactory experiences can regulate the morphological plasticity of different dendritic spines in the granule cell.
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26
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Ohmachi M, Fujiwara Y, Muramatsu S, Yamada K, Iwata O, Suzuki K, Wang DO. A modified single-cell electroporation method for molecule delivery into a motile protist, Euglena gracilis. J Microbiol Methods 2016; 130:106-111. [PMID: 27558617 DOI: 10.1016/j.mimet.2016.08.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/19/2016] [Accepted: 08/19/2016] [Indexed: 12/31/2022]
Abstract
Single-cell transfection is a powerful technique for delivering chemicals, drugs, or probes into arbitrary, specific single cells. This technique is especially important when the analysis of molecular function and cellular behavior in individual microscopic organisms such as protists requires the precise identification of the target cell, as fluorescence labeling of bulk populations makes tracking of individual motile protists virtually impossible. Herein, we have modified current single-cell electroporation techniques for delivering fluorescent markers into single Euglena gracilis, a motile photosynthetic microalga. Single-cell electroporation introduced molecules into individual living E. gracilis cells after a negative pressure was applied through a syringe connected to the micropipette to the target cell. The new method achieves high transfection efficiency and viability after electroporation. With the new technique, we successfully introduced a variety of molecules such as GFP, Alexa Fluor 488, and exciton-controlled hybridization-sensitive fluorescent oligonucleotide (ECHO) RNA probes into individual motile E. gracilis cells. We demonstrate imaging of endogenous mRNA in living E. gracilis without interfering with their physiological functions, such as swimming or division, over an extended period of time. Thus the modified single-cell electroporation technique is suitable for delivering versatile functional molecules into individual motile protists.
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Affiliation(s)
- Masashi Ohmachi
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yoshie Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shuki Muramatsu
- Research & Development Department, euglena Co., Ltd., Shiba, Minato-ku, Tokyo 108-0014, Japan
| | - Koji Yamada
- Research & Development Department, euglena Co., Ltd., Shiba, Minato-ku, Tokyo 108-0014, Japan
| | - Osamu Iwata
- Research & Development Department, euglena Co., Ltd., Shiba, Minato-ku, Tokyo 108-0014, Japan
| | - Kengo Suzuki
- Research & Development Department, euglena Co., Ltd., Shiba, Minato-ku, Tokyo 108-0014, Japan
| | - Dan Ohtan Wang
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan.
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27
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Shekaramiz E, Varadarajalu G, Day PJ, Wickramasinghe HK. Integrated Electrowetting Nanoinjector for Single Cell Transfection. Sci Rep 2016; 6:29051. [PMID: 27374766 PMCID: PMC4931508 DOI: 10.1038/srep29051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/14/2016] [Indexed: 11/09/2022] Open
Abstract
Single cell transfection techniques are essential to understand the heterogeneity between cells. We have developed an integrated electrowetting nanoinjector (INENI) to transfect single cells. The high transfection efficiency, controlled dosage delivery and ease of INENI fabrication promote the widespread application of the INENI in cell transfection assays.
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Affiliation(s)
- Elaheh Shekaramiz
- Department of Biomedical Engineering, University of California Irvine, California, USA
| | | | - Philip J. Day
- Manchester Institute of Biotechnology, the University of Manchester, Manchester, UK
| | - H. Kumar Wickramasinghe
- Department of Biomedical Engineering, University of California Irvine, California, USA
- Department of Electrical Engineering, University of California Irvine, California, USA
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28
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Herrgen L, Akerman CJ. Mapping neurogenesis onset in the optic tectum of Xenopus laevis. Dev Neurobiol 2016; 76:1328-1341. [PMID: 27012549 DOI: 10.1002/dneu.22393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 03/22/2016] [Accepted: 03/22/2016] [Indexed: 11/06/2022]
Abstract
Neural progenitor cells have a central role in the development and evolution of the vertebrate brain. During early brain development, neural progenitors first expand their numbers through repeated proliferative divisions and then begin to exhibit neurogenic divisions. The transparent and experimentally accessible optic tectum of Xenopus laevis is an excellent model system for the study of the cell biology of neurogenesis, but the precise spatial and temporal relationship between proliferative and neurogenic progenitors has not been explored in this system. Here we construct a spatial map of proliferative and neurogenic divisions through lineage tracing of individual progenitors and their progeny. We find a clear spatial separation of proliferative and neurogenic progenitors along the anterior-posterior axis of the optic tectum, with proliferative progenitors located more posteriorly and neurogenic progenitors located more anteriorly. Since individual progenitors are repositioned toward more anterior locations as they mature, this spatial separation likely reflects an increasing restriction in the proliferative potential of individual progenitors. We then examined whether the transition from proliferative to neurogenic behavior correlates with cellular properties that have previously been implicated in regulating neurogenesis onset. Our data reveal that the transition from proliferation to neurogenesis is associated with a small change in cleavage plane orientation and a more pronounced change in cell cycle kinetics in a manner reminiscent of observations from mammalian systems. Our findings highlight the potential to use the optic tectum of Xenopus laevis as an accessible system for the study of the cell biology of neurogenesis. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1328-1341, 2016.
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Affiliation(s)
- Leah Herrgen
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom.,Centre for Neuroregeneration, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, United Kingdom.,Euan MacDonald Centre for Motor Neurone Disease Research, University of Edinburgh, Edinburgh, EH16 4SB, United Kingdom
| | - Colin J Akerman
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom
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29
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Erdogan B, Ebbert PT, Lowery LA. Using Xenopus laevis retinal and spinal neurons to study mechanisms of axon guidance in vivo and in vitro. Semin Cell Dev Biol 2016; 51:64-72. [PMID: 26853934 DOI: 10.1016/j.semcdb.2016.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/01/2016] [Indexed: 11/26/2022]
Abstract
The intricate and precise establishment of neuronal connections in the developing nervous system relies on accurate navigation of growing axons. Since Ramón y Cajal's discovery of the growth cone, the phenomenon of axon guidance has been revealed as a coordinated operation of guidance molecules, receptors, secondary messengers, and responses driven by the dynamic cytoskeleton within the growth cone. With the advent of new and accelerating techniques, Xenopus laevis emerged as a robust model to investigate neuronal circuit formation during development. We present here the advantages of the Xenopus nervous system to our growing understanding of axon guidance.
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Affiliation(s)
- Burcu Erdogan
- Department of Biology, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
| | - Patrick T Ebbert
- Department of Biology, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
| | - Laura Anne Lowery
- Department of Biology, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA.
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30
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Huang YB, Hu CR, Zhang L, Yin W, Hu B. In Vivo Study of Dynamics and Stability of Dendritic Spines on Olfactory Bulb Interneurons in Xenopus laevis Tadpoles. PLoS One 2015; 10:e0140752. [PMID: 26485435 PMCID: PMC4617280 DOI: 10.1371/journal.pone.0140752] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 09/30/2015] [Indexed: 01/27/2023] Open
Abstract
Dendritic spines undergo continuous remodeling during development of the nervous system. Their stability is essential for maintaining a functional neuronal circuit. Spine dynamics and stability of cortical excitatory pyramidal neurons have been explored extensively in mammalian animal models. However, little is known about spiny interneurons in non-mammalian vertebrate models. In the present study, neuronal morphology was visualized by single-cell electroporation. Spiny neurons were surveyed in the Xenopus tadpole brain and observed to be widely distributed in the olfactory bulb and telencephalon. DsRed- or PSD95-GFP-expressing spiny interneurons in the olfactory bulb were selected for in vivo time-lapse imaging. Dendritic protrusions were classified as filopodia, thin, stubby, or mushroom spines based on morphology. Dendritic spines on the interneurons were highly dynamic, especially the filopodia and thin spines. The stubby and mushroom spines were relatively more stable, although their stability significantly decreased with longer observation intervals. The 4 spine types exhibited diverse preferences during morphological transitions from one spine type to others. Sensory deprivation induced by severing the olfactory nerve to block the input of mitral/tufted cells had no significant effects on interneuron spine stability. Hence, a new model was established in Xenopus laevis tadpoles to explore dendritic spine dynamics in vivo.
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Affiliation(s)
- Yu-Bin Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Chun-Rui Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Li Zhang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Wu Yin
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui Province, P. R. China
- * E-mail:
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Dempsey B, Turner AJ, Le S, Sun QJ, Bou Farah L, Allen AM, Goodchild AK, McMullan S. Recording, labeling, and transfection of single neurons in deep brain structures. Physiol Rep 2015; 3:3/1/e12246. [PMID: 25602013 PMCID: PMC4387759 DOI: 10.14814/phy2.12246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Genetic tools that permit functional or connectomic analysis of neuronal circuits are rapidly transforming neuroscience. The key to deployment of such tools is selective transfection of target neurons, but to date this has largely been achieved using transgenic animals or viral vectors that transduce subpopulations of cells chosen according to anatomical rather than functional criteria. Here, we combine single‐cell transfection with conventional electrophysiological recording techniques, resulting in three novel protocols that can be used for reliable delivery of conventional dyes or genetic material in vitro and in vivo. We report that techniques based on single cell electroporation yield reproducible transfection in vitro, and offer a simple, rapid and reliable alternative to established dye‐labeling techniques in vivo, but are incompatible with targeted transfection in deep brain structures. In contrast, we show that intracellular electrophoresis of plasmid DNA transfects brainstem neurons recorded up to 9 mm deep in the anesthetized rat. The protocols presented here require minimal, if any, modification to recording hardware, take seconds to deploy, and yield high recovery rates in vitro (dye labeling: 89%, plasmid transfection: 49%) and in vivo (dye labeling: 66%, plasmid transfection: 27%). They offer improved simplicity compared to the juxtacellular labeling technique and for the first time offer genetic manipulation of functionally characterized neurons in previously inaccessible brain regions. The ability to label individual neurons after electrophysiological characterization of their functional properties is a foundational technique in neuroscience. A number of approaches that achieve this goal have been described, but all are technically challenging. Here, we describe a simple approach that is rapid, reliable, and compatible with delivery of conventional dyes or large plasmid DNA molecules.
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Affiliation(s)
- Bowen Dempsey
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Anita J Turner
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Sheng Le
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Qi-Jian Sun
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Lama Bou Farah
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Andrew M Allen
- Department of Physiology, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Ann K Goodchild
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, Sydney, 2109, NSW, Australia
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Active calpain in phagocytically competent human neutrophils: electroinjection of fluorogenic calpain substrate. Biochem Biophys Res Commun 2015; 457:341-6. [PMID: 25576867 DOI: 10.1016/j.bbrc.2014.12.113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 12/26/2014] [Indexed: 11/20/2022]
Abstract
Calpain has been implicated in the apparent expansion of neutrophil plasma membrane that accompanies cell spreading and phagocytosis. In order to test this hypothesis, an internally quenched fluorescent peptide substrate of calpain-1 which increased in fluorescence on cleavage, was micro-electroinjected into neutrophils. The fluorescence intensity increased in a significant number of neutrophils, including those which appeared to be in a morphologically resting (spherical) state. In order to test whether calpain was activated by an elevation of cytosolic Ca(2+) during the injection, Ca(2+) chelators were added to the injectate and cytosolic free Ca(2+) in the receiving neutrophil was simultaneously monitored. It was shown that this approach could be used without raising Ca(2+) within the injected cell. Despite this, approximately 75% of individual neutrophils had calpain activity which consumed the substrate within approx. 100 s. It was found that all neutrophils had elevated calpain activity were phagocytically competent; whereas neutrophils with low or undetectable calpain activity failed to undergo phagocytosis. This association was consistent with the hypothesis that calpain activity within neutrophils was necessary for them to undergo efficient phagocytosis.
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Hassenklöver T, Manzini I. The olfactory system as a model to study axonal growth patterns and morphology in vivo. J Vis Exp 2014:e52143. [PMID: 25406975 PMCID: PMC4353389 DOI: 10.3791/52143] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems.
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Affiliation(s)
- Thomas Hassenklöver
- Institute of Neurophysiology and Cellular Biophysics and Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University of Göttingen
| | - Ivan Manzini
- Institute of Neurophysiology and Cellular Biophysics and Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University of Göttingen;
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Santra TS, Chang HY, Wang PC, Tseng FG. Impact of pulse duration on localized single-cell nano-electroporation. Analyst 2014; 139:6249-58. [PMID: 25320952 DOI: 10.1039/c4an01050g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We introduce a localized single-cell membrane nano-electroporation with controllable sequential molecular delivery by millisecond to nanosecond electrical pulses. An intense electrical field was generated by a pair of transparent indium tin oxide (ITO)-based nano-electrodes, which was confined to a narrow region of the single-cell membrane surface near the nano-electrode edges (approximately 2 μm × 50 nm area), whereas the remaining area of the membrane was unaffected. Moreover, a 250 nm SiO2 passivation layer on top of the nano-electrode reduced not only the thermal effect on the cell membrane surface, but it also avoided the generation of ions during the experiment, resulting in the reduction of cell toxicity and a significant enhancement of cell viability. Our approach precisely delivers dyes, Quantum Dots (QDs) and plasmids, through a localized region of single HeLa cells by considerably enhanced electrophoresis and diffusion effects with different duration of the pulsing process. The smaller molecules took less time to deliver into a single cell with a single pulse, whereas larger biomolecules took longer time even for multiple numbers of long lasting pulses. The system not only generates sequential well-controlled nano-pores allowing for the rapid recovery of cell membranes, but it also provides spatial, temporal and qualitative dosage control to deliver biomolecules into localized single-cell levels, which can be potentially beneficial for single cell studies and therapeutic applications.
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Affiliation(s)
- Tuhin Subhra Santra
- Institute of Nano Engineering and Microsystems, National Tsing Hua University, Taiwan.
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35
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Lewis KJ, Masterman B, Laffafian I, Dewitt S, Campbell JS, Hallett MB. Minimal impact electro-injection of cells undergoing dynamic shape change reveals calpain activation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1182-7. [PMID: 24607452 DOI: 10.1016/j.bbamcr.2014.02.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 02/09/2014] [Accepted: 02/28/2014] [Indexed: 10/25/2022]
Abstract
The ability of neutrophils to rapidly change shape underlies their physiological functions of phagocytosis and spreading. A major problem in establishing the mechanism is that conventional microinjection of substances and indicators interferes with this dynamic cell behaviour. Here we show that electroinjection, a "no-touch" point-and-shoot means of introducing material into the cell, is sufficiently gentle to allow neutrophils to be injected whilst undergoing chemokinesis and spreading without disturbing cell shape change behaviour. Using this approach, a fluorogenic calpain-1 selective peptide substrate was introduced into the cytosol of individual neutrophils undergoing shape changes. These data showed that (i) physiologically elevated cytosolic Ca(2+) concentrations were sufficient to trigger calpain-1 activation, blockade of Ca(2+) influx preventing calpain activation and (ii) calpain-1 activity was elevated in spreading neutrophil. These findings provide the first direct demonstration of a physiological role for Ca(2+) elevation in calpain-1 activation and rapid cell spreading. Electroinjection of cells undergoing dynamic shape changes thus opens new avenues of investigation for defining the molecular mechanism underlying dynamic cell shape changes.
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Affiliation(s)
- Kimberley J Lewis
- Neutrophil Signalling Group, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK
| | - Benjamin Masterman
- Neutrophil Signalling Group, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK
| | - Iraj Laffafian
- Neutrophil Signalling Group, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK
| | - Sharon Dewitt
- School of Dentistry, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK
| | - Jennie S Campbell
- Neutrophil Signalling Group, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK
| | - Maurice B Hallett
- Neutrophil Signalling Group, Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Heath Park, Cardiff University, Cardiff CF14 4XN, UK.
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Abstract
A key feature of the CNS is structural plasticity, the ability of neurons to alter their morphology and connectivity in response to sensory experience and other changes in the environment. How this structural plasticity is achieved at the molecular level is not well understood. We provide evidence that changes in sensory experience simultaneously trigger multiple signaling pathways that either promote or restrict growth of the dendritic arbor; structural plasticity is achieved through a balance of these opposing signals. Specifically, we have uncovered a novel, activity-dependent signaling pathway that restricts dendritic arborization. We demonstrate that the GTPase Rem2 is regulated at the transcriptional level by calcium influx through L-VGCCs and inhibits dendritic arborization in cultured rat cortical neurons and in the Xenopus laevis tadpole visual system. Thus, our results demonstrate that changes in neuronal activity initiate competing signaling pathways that positively and negatively regulate the growth of the dendritic arbor. It is the balance of these opposing signals that leads to proper dendritic morphology.
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37
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Microinjection methods for neutrophils. Methods Mol Biol 2014. [PMID: 24504952 DOI: 10.1007/978-1-62703-845-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The ability to microinject substances into the cytosol of living neutrophils opens the possibility of manipulating the chemistry within the cell and also of monitoring changes using indicators which otherwise cannot be introduced into the cell. However, neutrophils cannot be microinjected by the conventional glass pipette insertion method. Here, we outline two techniques which work well with neutrophils, namely, SLAM (simple lipid-assisted microinjection) and electroinjection.
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38
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Abstract
Antisense morpholino oligonucleotides (MOs) have become a valuable method to knock down protein levels, to block mRNA splicing, and to interfere with miRNA function. MOs are widely used to alter gene expression during development of Xenopus and zebra fish, where they are typically injected into the fertilized egg or blastomeres. Here, we present methods to use electroporation to target delivery of MOs to the central nervous system of Xenopus laevis or Xenopus tropicalis tadpoles. Briefly, MO electroporation is accomplished by injecting MO solution into the brain ventricle and driving the MOs into cells in the brain with current passing between two platinum plate electrodes, positioned on either side of the target brain area. The method is straightforward and uses standard equipment found in many neuroscience labs. A major advantage of electroporation is that it allows spatial and temporal control of MO delivery and therefore knockdown. Co-electroporation of MOs with cell-type specific fluorescent protein expression plasmids allows morphological analysis of cellular phenotypes. Furthermore, co-electroporation of MOs with rescuing plasmids allows assessment of specificity of the knockdown and phenotypic outcome. By combining MO-mediated manipulations with sophisticated assays of neuronal function, such as electrophysiological recording, behavioral assays, or in vivo time-lapse imaging of neuronal development, the functions of specific proteins and miRNAs within the developing nervous system can be elucidated. These methods can be adapted to apply antisense morpholinos to study protein and RNA function in a variety of complex tissues.
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Affiliation(s)
- Jennifer E Bestman
- The Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA, USA
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39
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Fast targeted gene transfection and optogenetic modification of single neurons using femtosecond laser irradiation. Sci Rep 2013; 3:3281. [PMID: 24257461 PMCID: PMC3836031 DOI: 10.1038/srep03281] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 10/15/2013] [Indexed: 12/20/2022] Open
Abstract
A prevailing problem in neuroscience is the fast and targeted delivery of DNA into selected neurons. The development of an appropriate methodology would enable the transfection of multiple genes into the same cell or different genes into different neighboring cells as well as rapid cell selective functionalization of neurons. Here, we show that optimized femtosecond optical transfection fulfills these requirements. We also demonstrate successful optical transfection of channelrhodopsin-2 in single selected neurons. We extend the functionality of this technique for wider uptake by neuroscientists by using fast three-dimensional laser beam steering enabling an image-guided "point-and-transfect" user-friendly transfection of selected cells. A sub-second transfection timescale per cell makes this method more rapid by at least two orders of magnitude when compared to alternative single-cell transfection techniques. This novel technology provides the ability to carry out large-scale cell selective genetic studies on neuronal ensembles and perform rapid genetic programming of neural circuits.
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40
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Pratt KG, Khakhalin AS. Modeling human neurodevelopmental disorders in the Xenopus tadpole: from mechanisms to therapeutic targets. Dis Model Mech 2013; 6:1057-65. [PMID: 23929939 PMCID: PMC3759326 DOI: 10.1242/dmm.012138] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Xenopus tadpole model offers many advantages for studying the molecular, cellular and network mechanisms underlying neurodevelopmental disorders. Essentially every stage of normal neural circuit development, from axon outgrowth and guidance to activity-dependent homeostasis and refinement, has been studied in the frog tadpole, making it an ideal model to determine what happens when any of these stages are compromised. Recently, the tadpole model has been used to explore the mechanisms of epilepsy and autism, and there is mounting evidence to suggest that diseases of the nervous system involve deficits in the most fundamental aspects of nervous system function and development. In this Review, we provide an update on how tadpole models are being used to study three distinct types of neurodevelopmental disorders: diseases caused by exposure to environmental toxicants, epilepsy and seizure disorders, and autism.
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Affiliation(s)
- Kara G. Pratt
- University of Wyoming, 1000 E University Avenue, Laramie, WY 82071, USA
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41
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Ruthazer ES, Schohl A, Schwartz N, Tavakoli A, Tremblay M, Cline HT. In vivo time-lapse imaging of neuronal development in Xenopus. Cold Spring Harb Protoc 2013; 2013:804-9. [PMID: 24003201 DOI: 10.1101/pdb.top077156] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In vivo fluorescence imaging of cells in the developing nervous system is greatly facilitated in specimens in which cells are brightly but sparsely labeled. In this article, we describe a number of techniques that can be used for delivering fluorophore to neurons in the albino Xenopus laevis tadpole. Fluorescent dye or DNA that encodes a fluorescent protein can be delivered to single cells by electroporation. Alternatively, multiple cells can be labeled with fluorescent dye introduced by local iontophoresis or with plasmid DNA introduced by bulk electroporation. Technical considerations and analysis methods for time-lapse imaging in living tissue are also discussed.
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42
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Kang W, Yavari F, Minary-Jolandan M, Giraldo-Vela JP, Safi A, McNaughton RL, Parpoil V, Espinosa HD. Nanofountain probe electroporation (NFP-E) of single cells. NANO LETTERS 2013; 13:2448-57. [PMID: 23650871 PMCID: PMC3736975 DOI: 10.1021/nl400423c] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The ability to precisely deliver molecules into single cells is of great interest to biotechnology researchers for advancing applications in therapeutics, diagnostics, and drug delivery toward the promise of personalized medicine. The use of bulk electroporation techniques for cell transfection has increased significantly in the past decade, but the technique is nonspecific and requires high voltage, resulting in variable efficiency and low cell viability. We have developed a new tool for electroporation using nanofountain probe (NFP) technology, which can deliver molecules into cells in a manner that is highly efficient and gentler to cells than bulk electroporation or microinjection. Here we demonstrate NFP electroporation (NFP-E) of single HeLa cells within a population by transfecting them with fluorescently labeled dextran and imaging the cells to evaluate the transfection efficiency and cell viability. Our theoretical analysis of the mechanism of NFP-E reveals that application of the voltage creates a localized electric field between the NFP cantilever tip and the region of the cell membrane in contact with the tip. Therefore, NFP-E can deliver molecules to a target cell with minimal effect of the electric potential on the cell. Our experiments on HeLa cells confirm that NFP-E offers single cell selectivity, high transfection efficiency (>95%), qualitative dosage control, and very high viability (92%) of transfected cells.
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Affiliation(s)
- Wonmo Kang
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
- iNfinitesimal LLC, Winnetka, IL 60093, USA
| | - Fazel Yavari
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Majid Minary-Jolandan
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | | | - Asmahan Safi
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Rebecca L. McNaughton
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
- iNfinitesimal LLC, Winnetka, IL 60093, USA
| | | | - Horacio D. Espinosa
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208, USA
- Corresponding author: , Phone: 847-467-5989; Fax: 847-491-3915
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43
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Delivery of molecules into cells using localized single cell electroporation on ITO micro-electrode based transparent chip. Biomed Microdevices 2013; 14:811-7. [PMID: 22674171 DOI: 10.1007/s10544-012-9660-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Single cell electroporation is one of the nonviral method which successfully allows transfection of exogenous macromolecules into individual living cell. We present localized cell membrane electroporation at single-cell level by using indium tin oxide (ITO) based transparent micro-electrodes chip with inverted microscope. A focused ion beam (FIB) technique has been successfully deployed to fabricate transparent ITO micro-electrodes with submicron gaps, which can generate more intense electric field to produce very localized cell membrane electroporation. In our approach, we have successfully achieved 0.93 μm or smaller electroporation region on the cell surface to inject PI (Propidium Iodide) dye into the cell with 60 % cell viability. This experiments successfully demonstrate the cell self-recover process from the injected PI dye intensity variation. Our localized cell membrane electroporation technique (LSCMEP) not only generates reversible electroporation process but also it provides a clear optical path for potentially monitoring/tracking of drugs to deliver in single cell level.
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44
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He J, Zhang G, Almeida AD, Cayouette M, Simons BD, Harris WA. How variable clones build an invariant retina. Neuron 2012; 75:786-98. [PMID: 22958820 PMCID: PMC3485567 DOI: 10.1016/j.neuron.2012.06.033] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2012] [Indexed: 01/02/2023]
Abstract
A fundamental question in developmental neuroscience is how a collection of progenitor cells proliferates and differentiates to create a brain of the appropriate size and cellular composition. To address this issue, we devised lineage-tracing assays in developing zebrafish embryos to reconstruct entire retinal lineage progressions in vivo and thereby provide a complete quantitative map of the generation of a vertebrate CNS tissue from individual progenitors. These lineage data are consistent with a simple model in which the retina is derived from a set of equipotent retinal progenitor cells (RPCs) that are subject to stochastic factors controlling lineage progression. Clone formation in mutant embryos reveals that the transcription factor Ath5 acts as a molecular link between fate choice and mode of cell division, giving insight into the elusive molecular mechanisms of histogenesis, the conserved temporal order by which neurons of different types exit the cell cycle.
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Affiliation(s)
- Jie He
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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45
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Straka H, Simmers J. Xenopus laevis: An ideal experimental model for studying the developmental dynamics of neural network assembly and sensory-motor computations. Dev Neurobiol 2012; 72:649-63. [DOI: 10.1002/dneu.20965] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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46
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Shen W, McKeown CR, Demas JA, Cline HT. Inhibition to excitation ratio regulates visual system responses and behavior in vivo. J Neurophysiol 2011; 106:2285-302. [PMID: 21795628 DOI: 10.1152/jn.00641.2011] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The balance of inhibitory to excitatory (I/E) synaptic inputs is thought to control information processing and behavioral output of the central nervous system. We sought to test the effects of the decreased or increased I/E ratio on visual circuit function and visually guided behavior in Xenopus tadpoles. We selectively decreased inhibitory synaptic transmission in optic tectal neurons by knocking down the γ2 subunit of the GABA(A) receptors (GABA(A)R) using antisense morpholino oligonucleotides or by expressing a peptide corresponding to an intracellular loop of the γ2 subunit, called ICL, which interferes with anchoring GABA(A)R at synapses. Recordings of miniature inhibitory postsynaptic currents (mIPSCs) and miniature excitatory PSCs (mEPSCs) showed that these treatments decreased the frequency of mIPSCs compared with control tectal neurons without affecting mEPSC frequency, resulting in an ∼50% decrease in the ratio of I/E synaptic input. ICL expression and γ2-subunit knockdown also decreased the ratio of optic nerve-evoked synaptic I/E responses. We recorded visually evoked responses from optic tectal neurons, in which the synaptic I/E ratio was decreased. Decreasing the synaptic I/E ratio in tectal neurons increased the variance of first spike latency in response to full-field visual stimulation, increased recurrent activity in the tectal circuit, enlarged spatial receptive fields, and lengthened the temporal integration window. We used the benzodiazepine, diazepam (DZ), to increase inhibitory synaptic activity. DZ increased optic nerve-evoked inhibitory transmission but did not affect evoked excitatory currents, resulting in an increase in the I/E ratio of ∼30%. Increasing the I/E ratio with DZ decreased the variance of first spike latency, decreased spatial receptive field size, and lengthened temporal receptive fields. Sequential recordings of spikes and excitatory and inhibitory synaptic inputs to the same visual stimuli demonstrated that decreasing or increasing the I/E ratio disrupted input/output relations. We assessed the effect of an altered I/E ratio on a visually guided behavior that requires the optic tectum. Increasing and decreasing I/E in tectal neurons blocked the tectally mediated visual avoidance behavior. Because ICL expression, γ2-subunit knockdown, and DZ did not directly affect excitatory synaptic transmission, we interpret the results of our study as evidence that partially decreasing or increasing the ratio of I/E disrupts several measures of visual system information processing and visually guided behavior in an intact vertebrate.
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Affiliation(s)
- Wanhua Shen
- The Dorris Neuroscience Center, The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037, USA
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47
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Li J, Erisir A, Cline H. In vivo time-lapse imaging and serial section electron microscopy reveal developmental synaptic rearrangements. Neuron 2011; 69:273-86. [PMID: 21262466 PMCID: PMC3052740 DOI: 10.1016/j.neuron.2010.12.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
Abstract
Dendrites, axons, and synapses are dynamic during circuit development; however, changes in microcircuit connections as branches stabilize have not been directly demonstrated. By combining in vivo time-lapse imaging of Xenopus tectal neurons with electron microscope reconstructions of imaged neurons, we report the distribution and ultrastructure of synapses on individual vertebrate neurons and relate these synaptic properties to dynamics in dendritic and axonal arbor structure over hours or days of imaging. Dynamic dendrites have a high density of immature synapses, whereas stable dendrites have sparser, mature synapses. Axons initiate contacts from multisynapse boutons on stable branches. Connections are refined by decreasing convergence from multiple inputs to postsynaptic dendrites and by decreasing divergence from multisynapse boutons to postsynaptic sites. Visual deprivation or NMDAR antagonists decreased synapse maturation and elimination, suggesting that coactive input activity promotes microcircuit development by concurrently regulating synapse elimination and maturation of remaining contacts.
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Affiliation(s)
- Jianli Li
- The Scripps Research Institute, La Jolla, CA 92037
| | - Alev Erisir
- Department of Psychology, University of Virginia, Charlottesville, VA 22904
| | - Hollis Cline
- The Scripps Research Institute, La Jolla, CA 92037
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48
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Yuan TF, Menéndez-González M, Arias-Carrión O. Single neuron electroporation in manipulating and measuring the central nervous system. Int Arch Med 2010; 3:28. [PMID: 21054865 PMCID: PMC2987861 DOI: 10.1186/1755-7682-3-28] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 11/05/2010] [Indexed: 01/20/2023] Open
Abstract
The development and application of single neuron electroporation largely advanced the use of traditional genetics in investigations of the central nervous system. This quick and accurate manipulation of the brain at individual neuron level allowed the gain and loss of functional analyses of different genes and/or proteins. This manuscript reviewed the development of the technique and discussed some technical aspects in practical manipulations. Then the manuscript summarized the potential applications with this technique. Last but not least, the technique showed prospective future when combined with other modern methods in neuroscience research.
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49
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Feng Y, Yan T, Zheng J, Ge X, Mu Y, Zhang Y, Wu D, Du JL, Zhai Q. Overexpression of Wldsor Nmnat2 in mauthner cells by single-cell electroporation delays axon degeneration in live zebrafish. J Neurosci Res 2010; 88:3319-27. [DOI: 10.1002/jnr.22498] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Takao D, Kamimura S. Geometry-specific heterogeneity of the apparent diffusion rate of materials inside sperm cells. Biophys J 2010; 98:1582-8. [PMID: 20409478 DOI: 10.1016/j.bpj.2009.12.4314] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 12/15/2009] [Accepted: 12/24/2009] [Indexed: 11/28/2022] Open
Abstract
In sea urchin spermatozoa, the energy source powering flagellar motion is provided as ATP produced by mitochondria located at the proximal ends of flagella. However, the bottleneck structure between the sperm head and the flagellar tail seems to restrict the free entry of ATP from mitochondria into the tail region. To test this possibility, we investigated the diffusion properties in sperm cells using fluorescence recovery after photobleaching. We found that the rate of fluorescence recovery in the head region was approximately 10% of that observed in the flagellar tail regions. We also found that, even within the tail region, rates varied depending on location, i.e., rates were slower at the more distal regions. Using computational analysis, the rate heterogeneity was shown to be caused mainly by the geometry of the sperm structure, even if little or no difference in diffusion rates through the neck region was assumed. Therefore, we concluded that materials such as ATP would generally diffuse freely between the heads and the flagella of sperm cells. We believe these findings regarding the diffusion properties inside spermatozoa provide further insights into material transportation and chemical signaling inside eukaryotic cilia and flagella.
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Affiliation(s)
- Daisuke Takao
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
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