This work was supported by the National Institute for Mental Health, and National Science Foundation. Special thanks to Dr. Jen Gutzman, Dr. Amanda Dickinson and other Sive lab members for many useful discussions and constructive criticism, and to Olivier Paugois for expert fish husbandry.

1. Preparing Microinjection Needles and Cell Tram
<ol>
	<li>Fill Eppendorf CellTram oil microinjector apparatus with mineral oil according to manufacturer's instructions.</li>
	<li>Prepare microinjection needles by pulling capillary tubes using Sutter instruments needle puller.</li>
	<li>Mount needle on micromanipulator connected to Eppendorf CellTram.</li>
	<li>Carefully break the tip of the needle. For uniform tip size, measure with a micrometer, or compare to a reference needle.</li>
	<li>Fill the length of the needle with oil, using the CellTram to push oil down the length, being careful to avoid any bubbles.</li>
</ol>
2. Preparing the Embryos
<ol>
	<li>Poke holes in a 1% agarose coated dish with a 1-200 &mu;l pipette tip, and remove agarose plugs. Fill dish with embryo media (made according to Westerfield25).</li>
	<li>Using forceps, dechorionate embryos under stereomicroscope.</li>
	<li>Transfer dechorionated embryos into agarose coated dish.</li>
	<li>To anesthetize embryos, add Tricaine (0.1 mg/ml) to agarose dish until embryos stop moving (made according to Westerfield25).</li>
</ol>
3. Draining the eCSF
<ol>
	<li>Orient the embryos with their tails in the holes of the agarose and their posterior sides closest to the micromanipulator, allowing for visualization of the dorsal side of the brain.</li>
	<li>Position the needle at the rhombomere 0/1 hinge-point or the widest point of hindbrain ventricle (Figure 1A).</li>
	<li>Carefully pierce roof plate of hindbrain ventricle being sure not to go through the depth of the brain into the yolk.</li>
	<li>Drain the eCSF using the CellTram and collect fluid in microinjection needle. Be careful to avoid any cells.</li>
</ol>
4. Collecting the eCSF for Composition Analysis
<ol>
	<li>Once the eCSF is collected in the needle, carefully stop suction from the CellTram.</li>
	<li>Move the dish out from under the needle and carefully position the needle into a tube containing the desired buffer.</li>
	<li>Using the CellTram, drain the eCSF out of the needle into the buffer trying to avoid contaminating the solution with oil.</li>
	<li>In order to remove cells that you have aspirated along with the eCSF, spin eCSF at 10,000 x g. Collect uncontaminated eCSF (supernatant) and store at -80 &deg;C until ready for further analysis.</li>
</ol>
5. Reintroduction of Selected Factors
<ol>
	<li>Drain the eCSF every 2 hr during desired time interval, since the fluid is replenished within that time period. Between drainage time-points, remove the needle and store the embryos at 28.5 &deg;C or desired temperature.</li>
	<li>Load second micropipette needle with test factor.</li>
	<li>Place needle into micromanipulator attached to microinjector.</li>
	<li>Adjust injection volume to 1 nl by measuring the drop size in oil and adjusting injection time and pressure.</li>
	<li>Inject 1-2 nl into brain ventricles as described previously26.</li>
</ol>

<ol>
	<li>Chodobski, A., Szmydynger-Chodobska, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Choroid+plexus:+target+for+polypeptides+and+site+of+their+synthesis.">Choroid plexus: target for polypeptides and site of their synthesis.</a> Microsc. Res. Tech. 52, 65-82 (2001).</li><li>Redzic, Z. B., Preston, J. E., Duncan, J. A., Chodobski, A., Szmydynger-Chodobska, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+choroid+plexus-cerebrospinal+fluid+system:+from+development+to+aging.">The choroid plexus-cerebrospinal fluid system: from development to aging.</a> Curr. Top. Dev. Biol. 71, 1-52 (2005).</li><li>Brown, P. D., Davies, S. L., Speake, T., Millar, I. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+of+cerebrospinal+fluid+production.">Molecular mechanisms of cerebrospinal fluid production.</a> Neuroscience. 129, 957-970 (2004).</li><li>Praetorius, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+and+solute+secretion+by+the+choroid+plexus.">Water and solute secretion by the choroid plexus.</a> Pflugers Arch. 454, 1-18 (2007).</li><li>Speake, T., Whitwell, C., Kajita, H., Majid, A., Brown, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+CSF+secretion+by+the+choroid+plexus.">Mechanisms of CSF secretion by the choroid plexus.</a> Microsc. Res. Tech. 52, 49-59 (2001).</li><li>Garcia-Lecea, M., Kondrychyn, I., Fong, S. 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I., Martin, C., Carnicero, E., Bueno, D., Gato, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebrospinal+fluid+control+of+neurogenesis+induced+by+retinoic+acid+during+early+brain+development.">Cerebrospinal fluid control of neurogenesis induced by retinoic acid during early brain development.</a> Dev. Dyn. 240, 1650-1659 (2011).</li><li>Miyan, J. A., Zendah, M., Mashayekhi, F., Owen-Lynch, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebrospinal+fluid+supports+viability+and+proliferation+of+cortical+cells+in+vitro,+mirroring+in+vivo+development.">Cerebrospinal fluid supports viability and proliferation of cortical cells in vitro, mirroring in vivo development.</a> Cerebrospinal Fluid Res. 3, 2 (2006).</li><li>Mashayekhi, F., Bannister, C. M., Miyan, J. 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Biol. 321, 51-63 (2008).</li><li>Parada, C., Gato, A., Bueno, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammalian+embryonic+cerebrospinal+fluid+proteome+has+greater+apolipoprotein+and+enzyme+pattern+complexity+than+the+avian+proteome.">Mammalian embryonic cerebrospinal fluid proteome has greater apolipoprotein and enzyme pattern complexity than the avian proteome.</a> J. Proteome Res. 4, 2420-2428 (2005).</li><li>Gato, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+cerebro-spinal+fluid+protein+composition+in+early+developmental+stages+in+chick+embryos.">Analysis of cerebro-spinal fluid protein composition in early developmental stages in chick embryos.</a> J. Exp. Zool. A Comp. Exp. Biol. 301, 280-289 (2004).</li><li>Westerfield, M., Sprague, J., Doerry, E., Douglas, S., Grp, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Zebrafish+Information+Network+(ZFIN):+a+resource+for+genetic,+genomic+and+developmental+research.">The Zebrafish Information Network (ZFIN): a resource for genetic, genomic and developmental research.</a> Nucleic Acids Res. 29, 87-90 (2001).</li><li>Gutzman, J. H., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish+Brain+Ventricle+Injection.">Zebrafish Brain Ventricle Injection.</a> J. Vis. Exp. (26), e1218 (2009).</li><li>Parada, C., Gato, A., Bueno, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=All-trans+retinol+and+retinol-binding+protein+from+embryonic+cerebrospinal+fluid+exhibit+dynamic+behaviour+during+early+central+nervous+system+development.">All-trans retinol and retinol-binding protein from embryonic cerebrospinal fluid exhibit dynamic behaviour during early central nervous system development.</a> Neuroreport. 19, 945-950 (2008).</li><li>Parada, C., Escola-Gil, J. C., Bueno, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-density+lipoproteins+from+embryonic+cerebrospinal+fluid+are+required+for+neural+differentiation.">Low-density lipoproteins from embryonic cerebrospinal fluid are required for neural differentiation.</a> J. Neurosci. Res. 86, 2674-2684 (2008).</li><li>Kramer-Zucker, A. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cilia-driven+fluid+flow+in+the+zebrafish+pronephros,+brain+and+Kupffer's+vesicle+is+required+for+normal+organogenesis.">Cilia-driven fluid flow in the zebrafish pronephros, brain and Kupffer's vesicle is required for normal organogenesis.</a> Development. 132, 1907-1921 (2005).</li><li>Lowery, L. A., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Initial+formation+of+zebrafish+brain+ventricles+occurs+independently+of+circulation+and+requires+the+nagie+oko+and+snakehead/atp1a1a.1+gene+products.">Initial formation of zebrafish brain ventricles occurs independently of circulation and requires the nagie oko and snakehead/atp1a1a.1 gene products.</a> Development. 132, 2057-2067 (2005).</li><li>Lowery, L. A., De Rienzo, G., Gutzman, J. H., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+classification+of+zebrafish+brain+morphology+mutants.">Characterization and classification of zebrafish brain morphology mutants.</a> Anat. Rec. (Hoboken). 292, 94-106 (2009).</li></ol>

No conflicts of interest declared.

Use of this technique to manually drain eCSF from zebrafish brain ventricles will be useful for determining the requirement for eCSF during development. In addition, this technique will allow description of the eCSF protein profile over the course of embryonic development. Identification of different proteins during this time will enable further investigation into the function of the CSF and its potential role during brain development. In amniotes, some factors identified in eCSF (IGF2, FGF2, retinoic acid, and apolipop...

<table><tbody><tr><td>Eppendorf CellTram Oil</td><td>Eppendorf</td><td>516 000.025</td><td></td></tr><tr><td>Mineral Oil </td><td>Sigma</td><td>M8410</td><td></td></tr><tr><td>Tricaine powder</td><td>Sigma</td><td>A5040</td><td></td></tr><tr><td>Capillary Tubes</td><td>FHC Inc.</td><td>30-30-1</td><td></td></tr></tbody></table>

manual drainage of the zebrafish embryonic brain ventricles

Cerebrospinal fluid (CSF) is a protein rich fluid contained within the brain ventricles. It is present during early vertebrate embryonic development and persists throughout life. Adult CSF is thought to cushion the brain, remove waste, and carry secreted molecules1,2. In the adult and older embryo, the majority of CSF is made by the choroid plexus, a series of highly vascularized secretory regions located adjacent to the brain ventricles3-5. In zebrafish, the choroid plexus is fully formed at 144 hours post fertilization (hpf)6. Prior to this, in both zebrafish and other vertebrate embryos including mouse, a significant amount of embryonic CSF (eCSF) is present . These data and studies in chick suggest that the neuroepithelium is secretory early in development and may be the major source of eCSF prior to choroid plexus development7.
eCSF contains about three times more protein than adult CSF, suggesting that it may have an important role during development8,9. Studies in chick and mouse demonstrate that secreted factors in the eCSF, fluid pressure, or a combination of these, are important for neurogenesis, gene expression, cell proliferation, and cell survival in the neuroepithelium10-20. Proteomic analyses of human, rat, mouse, and chick eCSF have identified many proteins that may be necessary for CSF function. These include extracellular matrix components, apolipoproteins, osmotic pressure regulating proteins, and proteins involved in cell death and proliferation21-24. However, the complex functions of the eCSF are largely unknown.
We have developed a method for removing eCSF from zebrafish brain ventricles, thus allowing for identification of eCSF components and for analysis of the eCSF requirement during development. Although more eCSF can be collected from other vertebrate systems with larger embryos, eCSF can be collected from the earliest stages of zebrafish development, and under genetic or environmental conditions that lead to abnormal brain ventricle volume or morphology. Removal and collection of eCSF allows for mass spectrometric analysis, investigation of eCSF function, and reintroduction of select factors into the ventricles to assay their function. Thus the accessibility of the early zebrafish embryo allows for detailed analysis of eCSF function during development.

An example of a drained brain ventricle is shown in Figure 1B-C. Brain ventricles are collapsed as they lack eCSF (Figure 1B vs. C). As seen in dorsal images (Figure 1B-C, and Figure 2A-D) the hindbrain neuroepithelium does retain its characteristic morphology and seems to be open despite lack of eCSF likely due to robust hinge-points. However, lateral views (Figure 2A'-D') demonstrate that the hindbrain ventricle has been drained, consi...

Watch this Scientific Journal Video about Manual Drainage of the Zebrafish Embryonic Brain Ventricles at JoVE.com

Manual Drainage of the Zebrafish Embryonic Brain Ventricles

We present a method to collect cerebrospinal fluid (CSF) and to create a system which lacks CSF within the embryonic zebrafish brain ventricular system. This allows for further examination of CSF composition and its requirement during embryonic brain development.

Cerebrospinal fluid  (CSF) is a protein rich fluid contained within the brain ventricles. It is  present during early vertebrate embryonic development and ...

manual-drainage-of-the-zebrafish-embryonic-brain-ventricles

Universidad de Cartagena UDEC

Research

JoVE Journal

Neuroscience

9.9K Views.  Massachusetts Institute of Technology. We present a method to collect cerebrospinal fluid (CSF) and to create a system which lacks CSF within the embryonic zebrafish brain ventricular system. This allows for further examination of CSF composition and its requirement during embryonic brain development.

Video: Manual Drainage of the Zebrafish Embryonic Brain Ventricles

Isolation and Culture of Adult Zebrafish Brain-derived Neurospheres

The zebrafish is a highly relevant model organism for understanding the cellular and molecular mechanisms involved in neurogenesis and brain regeneration in vertebrates. However, an in-depth analysis of the molecular mechanisms underlying zebrafish adult neurogenesis has been limited due to the lack of a reliable protocol for isolating and culturing neural adult stem/progenitor cells. Here we provide a reproducible method to examine adult neurogenesis using a neurosphere assay derived from zebrafish whole brain or from the telencephalon, tectum and cerebellum regions of the adult zebrafish brain. The protocol involves, first the microdissection of zebrafish adult brain, then single cell dissociation and isolation of self-renewing multipotent neural stem/progenitor cells. The entire procedure takes eight days. Additionally, we describe how to manipulate gene expression in zebrafish neurospheres, which will be particularly useful to test the role of specific signaling pathways during adult neural stem/progenitor cell proliferation and differentiation in zebrafish.

Here we provide a reproducible method to examine adult neurogenesis using a neurosphere assay derived from the whole brain or from either the telencephalic, tectal or cerebellar regions of the adult zebrafish brain. Additionally, we describe the procedure to manipulate gene expression in zebrafish neurospheres.

The zebrafish is a highly relevant model organism for understanding the cellular and molecular mechanisms involved in neurogenesis and brain regeneration ...

Developmental Biology

An Assay for Permeability of the Zebrafish Embryonic Neuroepithelium

The brain ventricular system is conserved among vertebrates and is composed of a series of interconnected cavities called brain ventricles, which form during the earliest stages of brain development and are maintained throughout the animal's life. The brain ventricular system is found in vertebrates, and the ventricles develop after neural tube formation, when the central lumen fills with cerebrospinal fluid (CSF) 1,2. CSF is a protein rich fluid that is essential for normal brain development and function3-6.
In zebrafish, brain ventricle inflation begins at approximately 18 hr post fertilization (hpf), after the neural tube is closed. Multiple processes are associated with brain ventricle formation, including formation of a neuroepithelium, tight junction formation that regulates permeability and CSF production. We showed that the Na,K-ATPase is required for brain ventricle inflation, impacting all these processes 7,8, while claudin 5a is necessary for tight junction formation 9. Additionally, we showed that "relaxation" of the embryonic neuroepithelium, via inhibition of myosin, is associated with brain ventricle inflation.
To investigate the regulation of permeability during zebrafish brain ventricle inflation, we developed a ventricular dye retention assay. This method uses brain ventricle injection in a living zebrafish embryo, a technique previously developed in our lab10, to fluorescently label the cerebrospinal fluid. Embryos are then imaged over time as the fluorescent dye moves through the brain ventricles and neuroepithelium. The distance the dye front moves away from the basal (non-luminal) side of the neuroepithelium over time is quantified and is a measure of neuroepithelial permeability (Figure 1). We observe that dyes 70 kDa and smaller will move through the neuroepithelium and can be detected outside the embryonic zebrafish brain at 24 hpf (Figure 2).
This dye retention assay can be used to analyze neuroepithelial permeability in a variety of different genetic backgrounds, at different times during development, and after environmental perturbations. It may also be useful in examining pathological accumulation of CSF. Overall, this technique allows investigators to analyze the role and regulation of permeability during development and disease.

We describe a live whole animal quantitative measurement for permeability of the embryonic zebrafish brain. The technique analyzes the ability to retain cerebrospinal fluid and molecules of different molecular weights within the neural tube lumen and quantifies their movement out of the ventricles. This method is useful for determining differences in epithelial permeability and maturation during development and disease.

The brain ventricular system is conserved among vertebrates and is composed of a series of interconnected cavities called brain ventricles, which form ...

Live Imaging of the Zebrafish Embryonic Brain by Confocal Microscopy

In this video, we demonstrate the method our lab has developed to analyze the cell shape changes and rearrangements required to bend and fold the developing zebrafish brain (Gutzman et al, 2008). Such analysis affords a new understanding of the underlying cell biology required for development of the 3D structure of the vertebrate brain, and significantly increases our ability to study neural tube morphogenesis. The embryonic zebrafish brain is shaped beginning at 18 hours post fertilization (hpf) as the ventricles within the neuroepithelium inflate. By 24 hpf, the initial steps of neural tube morphogenesis are complete. Using the method described here, embryos at the one cell stage are injected with mRNA encoding membrane-targeted green fluorescent protein (memGFP). After injection and incubation, the embryo, now between 18 and 24 hpf, is mounted, inverted, in agarose and imaged by confocal microscopy. Notably, the zebrafish embryo is transparent making it an ideal system for fluorescent imaging. While our analyses have focused on the midbrain-hindbrain boundary and the hindbrain, this method could be extended for analysis of any region in the zebrafish to a depth of 
80-100 &mu;m.

In this video, we demonstrate a method by which to analyze the developing vertebrate brain in live zebrafish embryos at single cell resolution by confocal microscopy. This includes the method by which we inject the single-cell zebrafish embryo and subsequently mount and image the developing brain.

In this video, we demonstrate the method our lab has developed to analyze the cell shape changes and rearrangements required to bend and fold the ...

Biology

Zebrafish Brain Ventricle Injection

Proper brain ventricle formation during embryonic brain development is required for normal brain function.  Brain ventricles are the highly conserved cavities within the brain that are filled with cerebrospinal fluid.  In zebrafish, after neural tube formation, the neuroepithelium undergoes a series of constrictions and folds while it fills with fluid resulting in brain ventricle formation.  In order to understand the process of ventricle formation, and the neuroepithelial shape changes that occur at the same time, we needed a way to visualize the ventricle space in comparison to the brain tissue.  However, the nature of transparent zebrafish embryos makes it difficult to differentiate the tissue from the ventricle space.  Therefore, we developed a brain ventricle injection technique where the ventricle space is filled with a fluorescent dye and imaged by brightfield and fluorescent microscopy.  The brightfield and the fluorescent images are then processed and superimposed in Photoshop.  This technique allows for visualization of the ventricle space with the fluorescent dye, in comparison to the shape of the neuroepithelium in the brightfield image.  Brain ventricle injection in zebrafish can be employed from 18 hours post fertilization through early larval stages.  We have used this technique extensively in our studies of brain ventricle formation and morphogenesis as well as in characterizing brain morphogenesis mutants (1-3).

After neural tube formation, the neuroepithelium constricts and folds while the tube fills with embryonic cerebrospinal fluid (eCSF) to form the embryonic brain ventricles. We developed this ventricle injection technique to better visualize the fluid filled space in contrast to the neuroepithelial shape in a live embryo.

Proper brain ventricle formation during embryonic brain development is required for normal brain function.  Brain ventricles are the highly conserved ...

Dissection and Lateral Mounting of Zebrafish Embryos: Analysis of Spinal Cord Development

The zebrafish spinal cord is an effective investigative model for nervous system research for several reasons. First, genetic, transgenic and gene knockdown approaches can be utilized to examine the molecular mechanisms underlying nervous system development. Second, large clutches of developmentally synchronized embryos provide large experimental sample sizes. Third, the optical clarity of the zebrafish embryo permits researchers to visualize progenitor, glial, and neuronal populations. Although zebrafish embryos are transparent, specimen thickness can impede effective microscopic visualization. One reason for this is the tandem development of the spinal cord and overlying somite tissue. Another reason is the large yolk ball, which is still present during periods of early neurogenesis. In this article, we demonstrate microdissection and removal of the yolk in fixed embryos, which allows microscopic visualization while preserving surrounding somite tissue. We also demonstrate semipermanent mounting of zebrafish embryos. This permits observation of neurodevelopment in the dorso-ventral and anterior-posterior axes, as it preserves the three-dimensionality of the tissue.

Developmental processes such as proliferation, patterning, differentiation, and axon guidance can be readily modeled in the zebrafish spinal cord. In this article, we describe a mounting procedure for zebrafish embryos, which optimizes visualization of these events.

The zebrafish spinal cord is an effective investigative model for nervous system research for several reasons. First, genetic, transgenic and gene ...

Electrophysiological Recording in the Brain of Intact Adult Zebrafish

Previously, electrophysiological studies in adult zebrafish have been limited to slice preparations or to eye cup preparations and electrorentinogram recordings. This paper describes how an adult zebrafish can be immobilized, intubated, and used for in vivo electrophysiological experiments, allowing recording of neural activity. Immobilization of the adult requires a mechanism to deliver dissolved oxygen to the gills in lieu of buccal and opercular movement. With our technique, animals are immobilized and perfused with habitat water to fulfill this requirement. A craniotomy is performed under tricaine methanesulfonate (MS-222; tricaine) anesthesia to provide access to the brain. The primary electrode is then positioned within the craniotomy window to record extracellular brain activity. Through the use of a multitube perfusion system, a variety of pharmacological compounds can be administered to the adult fish and any alterations in the neural activity can be observed. The methodology not only allows for observations to be made regarding changes in neurological activity, but it also allows for comparisons to be made between larval and adult zebrafish. This gives researchers the ability to identify the alterations in neurological activity due to the introduction of various compounds at different life stages.

This paper describes how an adult zebrafish can be immobilized, intubated, and used for in vivo electrophysiological experiments to allow recordings and manipulation of neural activity in an intact animal.

Previously, electrophysiological studies in adult zebrafish have been limited to slice preparations or to eye cup preparations and electrorentinogram ...

Eye Removal in Living Zebrafish Larvae to Examine Innervation-dependent Growth and Development of the Visual System

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis support continuous growth of the entire visual system, both in the eye and the brain. Coordinated growth between the retinae and the optic tectum ensures accurate retinotopic mapping as new neurons are added in the eyes and brain. To address whether retinal axons provide crucial information for regulating tectal stem and progenitor cell behaviors such as survival, proliferation, and/or differentiation, it is necessary to be able to compare innervated and denervated tectal lobes within the same animal and across animals. 
Surgical removal of one eye from living larval zebrafish followed by observation of the optic tectum achieves this goal. The accompanying video demonstrates how to anesthetize larvae, electrolytically sharpen tungsten needles, and use them to remove one eye. It next shows how to dissect brains from fixed zebrafish larvae. Finally, the video provides an overview of the protocol for immunohistochemistry and a demonstration of how to mount stained embryos in low-melting-point agarose for microscopy.

The article explains how to surgically remove eyes from living zebrafish larvae as the first step toward investigating how retinal input influences optic tectum growth and development. In addition, the article provides information about larval anesthetization, fixation, and brain dissection, followed by immunohistochemistry and confocal imaging.

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis ...

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing organisms, combined with the embryonic optical clarity, served as initial compelling attributes of this model. Over the past two decades, the success of this model has been further propelled by its amenability to large-scale mutagenesis screens and by the ease of transgenesis. More recently, gene-editing approaches have extended the power of the model.
For neurodevelopmental studies, the zebrafish embryo and larva provide a model to which multiple methods can be applied. Here, we focus on methods that allow the study of an essential property of neurons, electrical excitability. Our preparation for the electrophysiological study of zebrafish spinal neurons involves the use of veterinarian suture glue to secure the preparation to a recording chamber. Alternative methods for recording from zebrafish embryos and larvae involve the attachment of the preparation to the chamber using a fine tungsten pin1,2,3,4,5. A tungsten pin is most often used to mount the preparation in a lateral orientation, although it has been used to mount larvae dorsal-side up4. The suture glue has been used to mount embryos and larvae in both orientations. Using the glue, a minimal dissection can be performed, allowing access to spinal neurons without the use of an enzymatic treatment, thereby avoiding any resultant damage. However, for larvae, it is necessary to apply a brief enzyme treatment to remove the muscle tissue surrounding the spinal cord. The methods described here have been used to study the intrinsic electrical properties of motor neurons, interneurons, and sensory neurons at several developmental stages6,7,8,9.

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

This manuscript describes methods for electrophysiological recordings from spinal neurons of zebrafish embryos and larvae. The preparation maintains neurons in situ and often involves minimum dissection. These methods allow for the electrophysiological study of a variety of spinal neurons, from the initial electrical excitability acquisition through the early larval stages.

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing ...

Imaging and 3D Reconstruction of Cerebrovascular Structures in Embryonic Zebrafish

Zebrafish are a powerful tool to study developmental biology and pathology in vivo. The small size and relative transparency of zebrafish embryos make them particularly useful for the visual examination of processes such as heart and vascular development. In several recent studies transgenic zebrafish that express EGFP in vascular endothelial cells were used to image and analyze complex vascular networks in the brain and retina, using confocal microscopy. Descriptions are provided to prepare, treat and image zebrafish embryos that express enhanced green fluorescent protein (EGFP), and then generate comprehensive 3D renderings of the cerebrovascular system. Protocols include the treatment of embryos, confocal imaging, and fixation protocols that preserve EGFP fluorescence. Further, useful tips on obtaining high-quality images of cerebrovascular structures, such as removal the eye without damaging nearby neural tissue are provided. Potential pitfalls with confocal imaging are discussed, along with the steps necessary to generate 3D reconstructions from confocal image stacks using freely available open source software.

Imaging of cerebrovascular development in larval zebrafish is described. Techniques to facilitate 3D imaging and modify cerebrovascular development using chemical treatments are also provided.

Zebrafish are a powerful tool to study developmental biology and pathology in vivo.  The small size and relative transparency of zebrafish embryos make ...

Generation and Differentiation of Primary Neurospheres from Zebrafish Neural Stem Cells

Source: Lopez-Ramirez, M. A. et al., <a href="https://appjove.unicartagenaproxy.elogim.com/v/53617">Isolation and Culture of Adult Zebrafish Brain-derived Neurospheres.</a>&#160;J. Vis. Exp. (2016)
This video demonstrates the generation and differentiation of primary neurospheres. Neural stem cells from zebrafish, in the presence of growth factors, proliferate into free-floating neurospheres with self-renewal capacity, which later differentiate into glial cells and neurons.

1. Preparations

	Prepare 10 ml of dissection medium, and add 200 &#181;l of 100x penicillin-streptomycin into 9.8 ml of Dulbecco&#39;s Modified Eagle ...

Manual Drainage of the Zebrafish Embryonic Brain Ventricles

Summary

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Chapters in this video

Isolation and Culture of Adult Zebrafish Brain-derived Neurospheres

An Assay for Permeability of the Zebrafish Embryonic Neuroepithelium

Live Imaging of the Zebrafish Embryonic Brain by Confocal Microscopy

Zebrafish Brain Ventricle Injection

Dissection and Lateral Mounting of Zebrafish Embryos: Analysis of Spinal Cord Development

Electrophysiological Recording in the Brain of Intact Adult Zebrafish

Eye Removal in Living Zebrafish Larvae to Examine Innervation-dependent Growth and Development of the Visual System

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

Imaging and 3D Reconstruction of Cerebrovascular Structures in Embryonic Zebrafish

Generation and Differentiation of Primary Neurospheres from Zebrafish Neural Stem Cells