We thank T. Fritsch, A. Wolf-Asseburg, I. Linde and S.-M. Tokarski for excellent animal care and technical support. We are grateful to all members of the K&#246;ster lab for intense and helpful discussions. We gratefully acknowledge funding by the Deutsche Forschungsgemeinschaft (KO 1949/5-1) and the Federal State of Lower Saxony, Nieders&#228;chsisches Vorab (VWZN2889).

All animal work described here is in accordance with legal regulations (EU-Directive 2010/63). Maintenance and handling of fish has been approved by local authorities and by the animal welfare representative of the Braunschweig University of Technology and the Lower Saxony State Office of Consumer Protection and Food Safety (LAVES, Oldenburg, Germany; Az. &#167;4 (02.05) TSchB TU BS).
1. Preparation of Primary Cells from Zebrafish Embryos
<ol>
	<li>Preparation of 2 days post fertiliz...

<ol>
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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+the+Gal4-UAS+technique+for+targeted+gene+expression+in+the+zebrafish.">Use of the Gal4-UAS technique for targeted gene expression in the zebrafish.</a> Mechanisms of Development. 80, 153-158 (1999).</li><li>K&#246;ster, R. W., Fraser, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracing+transgene+expression+in+living+zebrafish+embryos.">Tracing transgene expression in living zebrafish embryos.</a> Developmental Biology. 233, 329-346 (2001).</li><li>Driever, W., Rangini, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+cell+line+derived+from+zebrafish+(Brachydanio+rerio)+embryos.">Characterization of a cell line derived from zebrafish (Brachydanio rerio) embryos.</a> In Vitro Cellular &amp; Developmental Biology - Animal. 29A, 749-754 (1993).</li><li>Badakov, R., Ja&#378;wi&#324;ska, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+transfection+of+primary+zebrafish+fibroblasts+by+nucleofection.">Efficient transfection of primary zebrafish fibroblasts by nucleofection.</a> Cytotechnology. 51, 105-110 (2006).</li><li>Senghaas, N., K&#246;ster, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+and+transfecting+zebrafish+PAC2+fibroblast+cells.">Culturing and transfecting zebrafish PAC2 fibroblast cells.</a> Cold Spring Harbor Protocols. , (2009).</li><li>Westerfield, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The zebrafish book. A guide for the laboratory use of zebrafish (Danio rerio). , (2007).</li><li>Basic methods in cellular and molecular biology. Using a hemacytometer to count cells. Journal of Visualized Experiments Available from: <a target="_blank" href="https://www.jove.com/science-education/5048/using-a-hemacytometer-to-count-cells">https://www.jove.com/science-education/5048/using-a-hemacytometer-to-count-cells</a> (2017)</li><li>Rupp, R. A., Snider, L., Weintraub, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xenopus+embryos+regulate+the+nuclear+localization+of+XMyoD.">Xenopus embryos regulate the nuclear localization of XMyoD.</a> Genes &amp; Development. 8, 1311-1323 (1994).</li><li>Piperno, G., Fuller, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monoclonal+antibodies+specific+for+an+acetylated+form+of+alpha-tubulin+recognize+the+antigen+in+cilia+and+flagella+from+a+variety+of+organisms.">Monoclonal antibodies specific for an acetylated form of alpha-tubulin recognize the antigen in cilia and flagella from a variety of organisms.</a> Journal of Cell Biology. 101 (6), 2085-2094 (1985).</li><li>Barden, J. A., Miki, M., Hambly, B. D., Dos Remedios, C. 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C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structures+and+chromosomal+localizations+of+two+human+genes+encoding+synaptobrevins+1+and+2.">Structures and chromosomal localizations of two human genes encoding synaptobrevins 1 and 2.</a> Journal of Biological Chemistry. 265, 17267-17273 (1990).</li><li>Griesbeck, O., Baird, G. S., Campbell, R. E., Zacharias, D. A., Tsien, R. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reducing+the+environmental+sensitivity+of+yellow+fluorescent+protein.+Mechanism+and+applications.">Reducing the environmental sensitivity of yellow fluorescent protein. Mechanism and applications.</a> Journal of Biological Chemistry. 276, 29188-29194 (2001).</li><li>Shaner, N. C., 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=A+bright+monomeric+green+fluorescent+protein+derived+from+Branchiostoma+lanceolatum.">A bright monomeric green fluorescent protein derived from Branchiostoma lanceolatum.</a> Nature Methods. 10, 407-409 (2013).</li><li>Campbell, R. 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The authors have nothing to disclose.

Here, we present two different protocols to culture primary cells from either 2 dpf zebrafish embryos or adult zebrafish brain.
The preparation of primary cell cultures from 2 dpf zebrafish is relatively easy to perform for anyone with experience in basic cell culture techniques. However, to obtain good and reproducible results, a sufficient number of embryos as starting material is crucial (100 is the minimum). During the raising of the embryos, all possible sources of contamination must be a...

The zebrafish (Danio rerio, D. rerio) is a popular model vertebrate for numerous fields of basic and biomedical research1. Zebrafish embryos develop rapidly ex utero, are transparent, and fit under a microscope, thus providing excellent prerequisites for studying vertebrate development in a living organism. Due to the genetic tractability of zebrafish2, many stable transgenic reporter lines with cell type-specific expression of various fluorescent markers have been established allowing for the observation of specific cell populations. The zebrafish community offers a broad variety of so-called Gal4-driver lines which carry a transgene expressing the synthetic Kal4TA4 (or the KalTA3-equivalent GalFF) gene with the Gal4-DNA-binding domain of yeast fused to viral transcriptional activation domains under the control of cell type-specific enhancers. These driver lines are crossed to effector lines which carry transgenes consisting of a defined upstream activating sequence (UAS) fused to a reporter gene. The Kal4TA4 protein binds to the UAS element, thus activating the cell type-selective expression of the reporter gene3,4. This approach allows for highly diverse combinatorial studies of almost all available enhancer and reporter elements in double-transgenic animals.
However, in-depth live imaging with focus on individual cells or their subcellular contents is limited in a whole and constantly changing embryo. To address specific cell biological questions with highest resolution, the use of cell cultures is often preferable. Some cell lines of zebrafish exist, but they are considered as heavily selected5,6,7 and their propagation is often time-consuming. Furthermore, all the available cell lines are fibroblast derived, limiting experiments using cell culture to one type of cells. Therefore, we established both an efficient and easy-to-use protocol to prepare primary cells directly from zebrafish embryos and adult zebrafish brain, together with approaches to increase the longevity of the culture and to broaden the diversity of cultivated cell types. In addition, we present a procedure to transfect embryonic primary cells with expression constructs for fluorescent organelle markers. Thus, cellular morphologies and subcellular structures can be analyzed with high spatial and temporal resolution in distinct cell types which retain their key features.

<table>
	<tbody>
		<tr>
			<td>Fish lines</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AB (wild-type)</td>
			<td></td>
			<td></td>
			<td>established by Streisinger and colleagues, available from the Zebrafish International Resource Center (ZIRC)</td>
		</tr>
		<tr>
			<td>Tg(ptf1a:eGFP)jh1</td>
			<td></td>
			<td></td>
			<td>stable transgenic line in which the enhancer of the zebrafish gene ptf1a drives expression of the fluorescent protein EGFP (Parsons et al., 2007)</td>
		</tr>
		<tr>
			<td>Tg(XITubb:DsRed)zf148</td>
			<td></td>
			<td></td>
			<td>stable transgenic line in which the Xenopus neural-specific beta tubulin promoter drives expression of the fluorescent protein DsRed&#160; (Peri and N&#252;sslein-Volhard, 2008)</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>Eppendorf</td>
			<td></td>
			<td>model 5804 R</td>
		</tr>
		<tr>
			<td>ChemiDoc MP imaging system</td>
			<td>BioRad</td>
			<td></td>
			<td>model XRS+, used to acquire black-and-white images of Petri dishes containing 1 da embryos</td>
		</tr>
		<tr>
			<td>confocal laser scanning microscope</td>
			<td>Leica microsystems</td>
			<td></td>
			<td>model SP8, equipped with 28 &#176;C temperature box and a 63 x objective</td>
		</tr>
		<tr>
			<td>epifluorescent microscope</td>
			<td>Leica microsystems</td>
			<td></td>
			<td>model DM5500B, equipped with 28 &#176;C temperature box and a 40 x objective</td>
		</tr>
		<tr>
			<td>Gene Pulser Xcell with capacitance extender</td>
			<td>BioRad</td>
			<td>1652661</td>
			<td>electroporation device</td>
		</tr>
		<tr>
			<td>Horizontal shaker</td>
			<td>GFL</td>
			<td></td>
			<td>model 3011</td>
		</tr>
		<tr>
			<td>incubator for cell culture (28 &#176;C)</td>
			<td>Memmert</td>
			<td></td>
			<td>model incubator I</td>
		</tr>
		<tr>
			<td>incubator for embryos (28 &#176;C)</td>
			<td>Heraeus</td>
			<td></td>
			<td>type B6120</td>
		</tr>
		<tr>
			<td>light microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td>model TELAVAL 31</td>
		</tr>
		<tr>
			<td>micro pipettes</td>
			<td>Gilson</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>sterile work bench</td>
			<td>Bio Base</td>
			<td></td>
			<td>with laminar flow and UV light</td>
		</tr>
		<tr>
			<td>tweezers</td>
			<td>Dumont</td>
			<td></td>
			<td>Style 5, Inox</td>
		</tr>
		<tr>
			<td>vertical tube rotator</td>
			<td>Labinco B.V.</td>
			<td></td>
			<td>model LD-79</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Image Lab Software</td>
			<td>BioRad</td>
			<td></td>
			<td>for the ChemiDoc MP imaging system from BioRad</td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>National Institutes of Health</td>
			<td></td>
			<td>used for counting 1 dpf embryos by applying the Count particles-tool to the respective black-and-white images; Rasband, W.S., ImageJ, U. S. National Institutes of Health, Bethesda, Maryland, USA, https://imagej.nih.gov/ij/. (1997-2016).</td>
		</tr>
		<tr>
			<td>LAS X</td>
			<td>Leica Microsystems</td>
			<td></td>
			<td>for both confocal and epifluorescent microscopes from Leica Microsystems</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Plasmids</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pCS-DCX-tdTomato</td>
			<td>K&#246;ster Lab</td>
			<td># 1599</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-eGFP</td>
			<td>K&#246;ster Lab</td>
			<td># 7</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-H2B-mseCFP</td>
			<td>K&#246;ster Lab</td>
			<td># 2379</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-mClover</td>
			<td>K&#246;ster Lab</td>
			<td># 3865</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-MitoTag-YFP</td>
			<td>K&#246;ster Lab</td>
			<td># 2199</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-ss-RFP-KDEL</td>
			<td>K&#246;ster Lab</td>
			<td># 4330</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pCS-VAMP1-mCitrine</td>
			<td>K&#246;ster Lab</td>
			<td># 2291</td>
			<td>based on the backbone pCS2+ (Rupp et al., 1994)</td>
		</tr>
		<tr>
			<td>pSK-UAS:mCherry</td>
			<td>K&#246;ster Lab</td>
			<td># 1062</td>
			<td>based on the pBluescript-backbone of Stratagene</td>
		</tr>
		<tr>
			<td>Plasmid numbers refer to the database entries of the K&#246;ster lab. Plasmids are available upon request.</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Plastic and glass ware</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BD Falcon Cell Strainer (40 &#181;m)</td>
			<td>FALCON</td>
			<td>REF 352340</td>
			<td>distributed by BD Bioscience, used as &#8220;landing net&#8221; to dip deyolked embryos into ethanol and to transfer them quickly to fresh cell culture medium</td>
		</tr>
		<tr>
			<td>1.5 mL reaction tubes</td>
			<td>Sarstedt</td>
			<td>72690550</td>
			<td></td>
		</tr>
		<tr>
			<td>24-well plate</td>
			<td>Sarstedt</td>
			<td>83.3922</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL falconic tube</td>
			<td>Sarstedt</td>
			<td>62.547.004</td>
			<td></td>
		</tr>
		<tr>
			<td>96-well plate</td>
			<td>Sarstedt</td>
			<td>83.3924.005</td>
			<td></td>
		</tr>
		<tr>
			<td>EasyStrainer (40 &#181;m)</td>
			<td>Greiner Bio-One</td>
			<td>542 040</td>
			<td>with venting slots; used to filter cells after collagenase-mediated dissociation</td>
		</tr>
		<tr>
			<td>electroporation cuvette (0.4 cm)</td>
			<td>Kisker</td>
			<td>4905022</td>
			<td></td>
		</tr>
		<tr>
			<td>glass coverslips</td>
			<td>Heinz Herenz Medizinalbedarf GmbH</td>
			<td>1051201</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides</td>
			<td>Thermo Fisher Scientific (Menzel Gl&#228;ser)</td>
			<td>631-0845</td>
			<td></td>
		</tr>
		<tr>
			<td>Neubauer chamber</td>
			<td>Henneberg-Sander GmbH</td>
			<td>9020-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Pasteur pipettes (plastic; 3 mL)</td>
			<td>A. Hartenstein</td>
			<td>PP05</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri dishes (plastic; diameter 10 cm)</td>
			<td>Sarstedt</td>
			<td>821473</td>
			<td>for zebrafish embryos</td>
		</tr>
		<tr>
			<td>pipette tips</td>
			<td>Sarstedt</td>
			<td>Blue (1000 &#181;l): 70762; Yellow (200 &#181;l): 70760002; White (10 &#181;L): 701116</td>
			<td></td>
		</tr>
		<tr>
			<td>sterile cell culture dishes (plastic; diameter 3 cm)</td>
			<td>TPP Techno Plastic Products AG</td>
			<td>93040</td>
			<td></td>
		</tr>
		<tr>
			<td>sterile cell culture dishes (plastic; diameter 6 cm)</td>
			<td>Sarstedt</td>
			<td>72690550</td>
			<td></td>
		</tr>
		<tr>
			<td>sterile Petri dishes (plastic; diameter 10 cm)</td>
			<td>Sarstedt</td>
			<td>83.3902</td>
			<td>for brain dissection</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Chemicals and Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>sodium chloride</td>
			<td>Roth</td>
			<td>0601.1</td>
			<td></td>
		</tr>
		<tr>
			<td>4 % paraformaldehyde in 1 x PBS</td>
			<td>Sigma-Aldrich</td>
			<td>16005</td>
			<td></td>
		</tr>
		<tr>
			<td>4&#39;,6-diamidino-2-phenylindole (DAPI)</td>
			<td>Thermo Fisher Scientific</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr>
			<td>calcium nitrate tetrahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>C1396</td>
			<td></td>
		</tr>
		<tr>
			<td>ethanol p.a. 100%</td>
			<td>Sigma-Aldrich</td>
			<td>46139</td>
			<td></td>
		</tr>
		<tr>
			<td>goat &#945;-mouse IgG (Fc specific) FITC conjugated</td>
			<td>Thermo Fisher Scientific</td>
			<td>31547</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Roth</td>
			<td>9105.4</td>
			<td></td>
		</tr>
		<tr>
			<td>high vacuum grease</td>
			<td>DOW CORNING</td>
			<td>3826-50</td>
			<td>silicon grease used for self-made glass bottom dishes</td>
		</tr>
		<tr>
			<td>magnesium sulfate heptahydrate</td>
			<td>Merck</td>
			<td>105886</td>
			<td></td>
		</tr>
		<tr>
			<td>methylene blue</td>
			<td>Serva</td>
			<td>29198.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Monoclonal Anti-Tubulin, Acetylated antibody</td>
			<td>Sigma-Aldrich</td>
			<td>T6793</td>
			<td></td>
		</tr>
		<tr>
			<td>Aqua-Poly/Mount (mounting medium)</td>
			<td>Polyscience</td>
			<td>18606</td>
			<td></td>
		</tr>
		<tr>
			<td>poly-L-lysine</td>
			<td>Biochrom</td>
			<td>L 7240</td>
			<td></td>
		</tr>
		<tr>
			<td>potasssion chloride</td>
			<td>Merck</td>
			<td>104938</td>
			<td></td>
		</tr>
		<tr>
			<td>Skim milk</td>
			<td>Roth</td>
			<td>68514-61-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Texas Red-X Phalloidin</td>
			<td>Thermo Fisher Scientific</td>
			<td>T7471</td>
			<td></td>
		</tr>
		<tr>
			<td>Tricaine</td>
			<td>Sigma-Aldrich</td>
			<td>E10521</td>
			<td>Synonym: Ethyl 3-aminobenzoate methanesulfonate</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>BioRad</td>
			<td>1610407</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue</td>
			<td>Gibco by Life Technologies</td>
			<td>15250061</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Enzymes</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>collagenase (Type 2)</td>
			<td>Thermo Fisher Scientific</td>
			<td>17101015</td>
			<td>dissolve powder in cell culture medium (8 mg/mL) and sterile-filter the solution, store aliquots at -20 &#176;C</td>
		</tr>
		<tr>
			<td>pronase (from Streptomyces griseus)</td>
			<td>Roche</td>
			<td>11459643001</td>
			<td>distributed by Sigma-Aldrich, dissolve in 30% Danieau (10 mg/mL) and store aliquots at -20 &#176;C</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Medium and solutions for cell culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>1 x PBS (Dulbecco&#39;s Phosphate Buffered Saline)</td>
			<td>Gibco by Life Technologies</td>
			<td>14190-169</td>
			<td>distributed by Thermo Fisher Scientific</td>
		</tr>
		<tr>
			<td>CO2-independent medium</td>
			<td>Gibco by Life Technologies</td>
			<td>18045054</td>
			<td>distributed by Thermo Fisher Scientific</td>
		</tr>
		<tr>
			<td>filtrated bovine serum (FBS)</td>
			<td>PAN-Biotech</td>
			<td></td>
			<td>individual batch</td>
		</tr>
		<tr>
			<td>glutamine 100 x</td>
			<td>Gibco by Life Technologies</td>
			<td>25030081</td>
			<td>distributed by Thermo Fisher Scientific</td>
		</tr>
		<tr>
			<td>Leibovitz&#39;s L-15 medium</td>
			<td>Gibco by Life Technologies</td>
			<td>11415049</td>
			<td>distributed by Thermo Fisher Scientific</td>
		</tr>
		<tr>
			<td>PenStrep (10,000 units/mL)</td>
			<td>Gibco by Life Technologies</td>
			<td>15140148</td>
			<td>distributed by Thermo Fisher Scientific</td>
		</tr>
	</tbody>
</table>

culture and transfection of zebrafish primary cells

Zebrafish embryos are transparent and develop rapidly outside the mother, thus allowing for excellent in vivo imaging of dynamic biological processes in an intact and developing vertebrate. However, the detailed imaging of the morphologies of distinct cell types and subcellular structures is limited in whole mounts. Therefore, we established an efficient and easy-to-use protocol to culture live primary cells from zebrafish embryos and adult tissue.
In brief, 2 dpf zebrafish embryos are dechorionated, deyolked, sterilized, and dissociated to single cells with collagenase. After a filtration step, primary cells are plated onto glass bottom dishes and cultivated for several days. Fresh cultures, as much as long term differenciated ones, can be used for high resolution confocal imaging studies. The culture contains different cell types, with striated myocytes and neurons being prominent on poly-L-lysine coating. To specifically label subcellular structures by fluorescent marker proteins, we also established an electroporation protocol which allows the transfection of plasmid DNA into different cell types, including neurons. Thus, in the presence of operator defined stimuli, complex cell behavior, and intracellular dynamics of primary zebrafish cells can be assessed with high spatial and temporal resolution. In addition, by using adult zebrafish brain, we demonstrate that the described dissociation technique, as well as the basic culturing conditions, also work for adult zebrafish tissue.

Figure 1G shows a transmitted light image of a typical culture derived from wild type embryos with striated myocytes and clusters of neuron-like cells being most abundant. To identify certain cell types more easily, a transgenic line with cell type-specific expression of a fluorescent protein can be used (Figure 1H).
Transfection of a pCS2+-based plasmid<sup class="xref...

Watch this Scientific Journal Video about Culture and Transfection of Zebrafish Primary Cells at JoVE.com

Culture and Transfection of Zebrafish Primary Cells

We present an efficient and easy-to-use protocol for preparing primary cell cultures of zebrafish embryos for transfection and live cell imaging as well as a protocol to prepare primary cells from adult zebrafish brain.

Zebrafish embryos are transparent and develop rapidly outside the mother, thus allowing for excellent in vivo imaging of dynamic biological processes in ...

This method provides the zebrafish community a tool for the the analysis of intercellular dynamics with a resolution unattainable in vivo. And also it allows to compensate for the lack of zebrafish cell lines. The main advantage of this technique is that you isolated and tranfect those primary cells directly from the original tissue so you do not need to keep cell lines.To begin the protocol prepare the zebrafish embryos two days post fertilization, or dpf. On day one set up several crossings of the zebrafish strain of choice. On day two mate to the fish and collect the eggs directly after spawning in a plastic 10 centimeter Petri dish.Remove the dead and contaminated eggs with a plastic Pasteur pipette. Wash the eggs once with Danieau 30%with 0.0001%weight per volume methylene blue. Then replace the medium with fresh Danieau 30%without methylene blue and incubate the eggs overnight at 28 degrees Celsius.On day three remove the dead and contaminated embryos and exchange the medium to Danieau 30%Then incubate the embryos overnight at 28 degrees Celsius. On day four remove the chorions by removing the medium until approximately 10 milliliters are left in the dish. Add one milliliter of one milligram per milliliter of pronase and incubate the embryos on a shaker for approximately 30 minutes at room temperature until all the chorions are detached.Next spread silicone grease around the hole on the underside of the dish bottoms and attach a cover slip using the grease as glue. Make sure that the grease seals the gap between the dish bottom and cover slip. Wash the glass bottomed dishes thoroughly but carefully with cold tap water and soap.Rinse the glass bottom dishes three times with deionized water to remove the soap. Then air dry the dish lids and dish bottoms and store them in a clean box until further use. On the day of culture preparation moisten the inside of both dish lids and dish bottoms with 70%ethanol.Place the dish lids and the dish bottoms facing the inner side up in a sterile workbench with laminar flow and UV light. Air dry the dishes until the ethanol has evaporated then apply UV light for 20 minutes. After this treatment dishes are assembled and sterile.To coat the dishes pipette 200 microliters of 0.1 milligram per milliliter poly-L-lysine in the middle of each glass bottom dish and spread the liquid on the cover slip by breaking surface tension with a pipette tip. Then incubate dishes for 60 minutes under the bench at room temperature. After the incubation wash them once with sterile 1x phosphate-buffered saline or PBS and remove the liquid.Keep dishes under the bench until further use. On day four the day of culture preparation transfer the embryos to a sterile cell culture dish with a fresh plastic Pasteur pipette. Remove the liquid step-wise until all the embryos are gathered in a big drop with a diameter of about two centimeters or less.Place the dish with the embryos in a sterile workbench and add carbon dioxide independent medium until the dish is half filled. To remove the yolk pipette the embryos up and down using a 200 microliter pipette tip. Successful deyolking can be recognized by the cloudiness of the medium.Next fill a cell culture dish with 70%ethanol and another cell culture dish with fresh cell culture medium. Use a cut off 1000 microliter pipette tip to transfer embryos into a sterile 40 micron cell strainer with a handle. Take the strainer by the handle and dip it into the dish with ethanol so that all embryos are submerged for five seconds.After the ethanol treatment immediately submerge the strainer with embryos in the dish with fresh cell culture medium. Then transfer the embryos into sterile 1.5 milliliter reaction tubes. Add collagenase type 2 to the embryos.Incubate the tubes on a vertical tube rotator. Dissociate the remaining cell clumps by pipetting the mixture up and down with a 1000 microliter pipette tip. Then filter the cell suspension through a sterile cell strainer with a venting slot into a 50 milliliter conical tube.Rinse the strainer with 10 milliliters of fresh cell culture medium. Centrifuge the cells for three minutes at 180 times g. After centrifugation carefully check for pellet formation.After that remove the supernatant and resuspend the cells in 200 microliters of fresh cell culture medium per 30 originally used embryos. Then pipette 200 microliters of the cell suspension directly on the glass area of a prepared poly-L-lysine coated glass bottom dish and let the cells attach for 60 minutes. Add six milliliters of fresh cell culture medium and incubate primary cells at 28 degrees Celsius.Then perform the desired imaging application using an inverted microscope at 28 degrees Celsius. Determine the cell number in a counting chamber. Then in a 1.5 milliliter reaction tube mix 10 micrograms of ultra-pure plasmid DNA with 0.5 million cells and adjust the total volume to 100 microliters with sterile PBS if needed.Thoroughly resuspend the solution for 20 seconds prior to electroporation. Next transfer the cell DNA mix immediately to an electroporation cuvette place the cuvette in an electroporation device and electroporate the sample. Directly after the electroporation transfer the cell DNA mix into a 1.5 milliliter reaction tube with 300 microliters of fresh cell culture medium.Finally plate 200 microliters of the cell suspension as done in previous sections. Using the method in this video transfection of the pCS2 positive-based plasmids encoding fluorescent organelle markers such as endoplasmic reticulum-targeted red fluorescent protein or mitochondria-targeted yellow fluorescent protein subcellular structures were visualized in great detail. Simultaneous analysis was performed via co-transfection of the fusion proteins MitoTag-YFP with the microtubule marker human doublecortin fused to the red fluorescent protein tdTomato and the nuclear marker Histone H2B fused to a cyan fluorescent protein.Selected images from a time lapse of the movement of vesicles positive for the membrane marker vesicle associated membrane protein one fused to the fluorescent protein mCitrine provides high temporal and spatial resolution. Morphological changes over time can be easily observed by labeling the whole cell by the expression of a bright fluorescent protein. They electroporation protocol is also suitable for combinatorial genetics.The dissociation technique and the basic culture conditions were also applied to adult brain tissue from wild type zebrafish and shows the progressive development of an initially debris-coated culture to a complex neuronal-like network. Thanks to the availability of many zebrafish models of human diseases and tissue-specific reporter lines our method can be used to describe the intracellular mechanisms that underline biogenesis with focus at specific cell types and developmental stages.

culture-and-transfection-of-zebrafish-primary-cells

Research

JoVE Journal

Developmental Biology

12.1K visualizações.  Braunschweig University of Technology. This method provides the zebrafish community a tool for the the analysis of intercellular dynamics with a resolution unattainable in vivo. And also it allows to compensate for the lack of zebrafish cell lines. The main advantage of this technique is that you isolated and tranfect those primary cells directly from the original tissue so you do not need to keep cell lines.To begin the protocol prepare the zebrafish embryos two days post fertilization, or dpf. On day one set up several cr...