Culture and Transfection of Zebrafish Primary Cells

Summary

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.

Abstract

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.

Introduction

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 ....

Protocol

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. §4 (02.05) TSchB TU BS).

1. Preparation of Primary Cells from Zebrafish Embryos

1. Preparation of 2 days post fertilization (dpf) zebrafish embryos
   1. Day 1: Set up several crossings of the zebrafish strain of choice and according to the specifications of....

Results

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

Discussion

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.......

Materials

List of materials used in this article

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