This work was supported by the NIH and PKD foundation to ZS. All animal experiments were conducted according to Yale Animal Resources Center (YARC) and Institutional Animal Care and Use Committee (IACUC) guidelines.

Part 1: Preparation of micropipettes, and microinjection chamber plates
<ol>
	<li>Fabricate micropipettes by heating and pulling borosilicate glass capillary tubes (World Precision Instruments, Inc., 1B100-4) in a micropipette puller device (Sutter Instruments Inc., Flaming/Brown P-97). Store in a Petri dish on top of small amount of clay or adhesive tape.</li>
	<li>Pour 1.5% agarose (American Bioanlytical, Inc., AB00972-00500) in 1x E3 medium plates molded with wedge-shaped troughs that will serve as an easy method for holding the embryos during the injection (as described in &#39;The Zebrafish Book&#34;) 1. Let agar chamber plates solidify before use and store at 4&#186;C.</li>
</ol>
Part 2: Preparation of RNA
One powerful approach for gene function studies is to microinject in vitro transcribed capped RNA in zebrafish embryos. Capped RNA behaves similarly to eukaryotic mRNAs found in vivo due to the presence of the CAP analog. Zebrafish researchers routinely utilize this method to overexpress or misexpress their gene of interest. In this demonstration, we will microinject an EGFP-tagged transcript and use live whole-embryo GFP-expression as a visible readout for a successful injection.
<ol>
	<li>Perform an in vitro CAP RNA transcription reaction on your transcript of interest. In our lab, we routinely insert a cDNA of interest into a pCS2+ vector and perform an in vitro synthesis reaction of large amounts of capped RNA using the mMessage mMachine SP6 kit (Ambion, Inc., AM1340).</li>
	<li>Purify the RNA sample by running it through the RNeasy Mini kit (Qiagen, Inc., 74104) or by phenol:chloroform extraction and isopropanol precipitation.</li>
	<li>Carefully determine the concentration of the RNA preparation and store at -80&#186;C until ready for use.</li>
	<li>On the day of the injection, thaw the RNA sample, vortex lightly and spin down briefly.</li>
	<li>Prepare a working solution with sterile water and a final concentration of 0.025 - 0.050% phenol red (Sigma-Aldrich Co., P0290). Phenol red serves as a visible marker for the injection of the solution into the embryo. In this article, we will prepare a working solution of 100 ng/uL EGFP mRNA with 0.050% phenol red.</li>
	<li>Keep working sample on ice and return RNA stock to -80&#176;C.</li>
	<li>Proceed to Part 4 when ready to inject this sample.</li>
</ol>
Part 3: Preparation of morpholino
Morpholino antisense oligonucleotides are widely used to modify gene expression by blocking translation of a targeted protein or by modifying pre-mRNA splicing 2,3. Morpholinos in the zebrafish serve as a powerful reverse genetics tool by knocking down gene function. In this article, we will microinject a morpholino oligo targeted to the translational initiation site of pkd2 (5&#8242;-AGGACGAACGCGACTGGAGCTCATC-3&#8242;). Based on previously established work, we expect the injected embryos to phenotypically mimic pkd2 mutant fish4.
<ol>
	<li>We routinely order 300 nmol of a morpholino oligo specifically designed for a gene of interest from Gene Tools, LLC (Philomath, OR).</li>
	<li>Add 100 uL sterile water to make a 3 mM stock solution. Aliquot the solution and store at -20&#176;C until ready for use.</li>
	<li>On the day of the injection, heat the morpholino solution at 65&#176;C for 5 minutes. Snap cool on ice immediately and spin briefly. This step denatures any secondary structures in the oligo and ensures that the solution is completely solubilized.</li>
	<li>Prepare a working solution by diluting the morpholino solution in sterile water and a final concentration of 0.025 - 0.050% phenol red. In this demonstration, we will be preparing a working solution of 0.50 mM pkd2 morpholino with 0.050% phenol red.</li>
	<li>Keep working solution at room temperature.</li>
	<li>Proceed to Part 4 when ready to inject this sample.----</li>
</ol>
Part 4: Filling the micropipette with your working solution
<ol>
	<li>Cut the distal tip of a micropipette with forceps or a surgical razorblade to create an opening that is just visible under a dissecting microscope (Nikon Instruments, Inc., SM2645) at 50X magnification.</li>
	<li>Place 2 uL of your working solution as a drop onto a coverslip.</li>
	<li>Attach the back of a micropipette to a 5 mL syringe fitted with tubing on a hypodermic needle and slightly submerge the distal tip of the micropipette into your drop of working solution. Take care not to break the tip of the micropipette.</li>
	<li>Siphon the working solution through the distal end of the micropipette by pulling the plunger of the syringe.</li>
</ol>
Part 5: Calibrating the micropipette injection volume
<ol>
	<li>Place a drop of mineral oil (American Bioanalytical, Inc., AB00921-00025) on a micrometer slide (Fisher, 12-561-SM1).</li>
	<li>Turn on power and air supply to the pressure-pulsed micro injector apparatus (World Precision Instruments Inc., PV830).</li>
	<li>Attach the micropipette to the micropipette holder of the micro injector apparatus. The micro injector is pressure regulated and discharges are activated by pressing the foot pedal.</li>
	<li>Under the dissection microscope, test the injection volume by using the micro injector to place a drop of your working solution onto the micrometer oil. Measure the diameter of the drop as it floats as a sphere on top of the oil.</li>
	<li>Adjust the duration and pressure of injection to carefully calibrate your volume of injection. This step aids in the reproducibility of the microinjection experiment. In this demonstration, all microinjections will be done with a drop diameter of 0.15 mm (approximately 1.76 nL in volume).</li>
	<li>Once your injection volume has been calibrated, use the &#8220;Hold&#8221; knob on the micro injector to prevent backfilling and leaking of the micropipette.</li>
</ol>
Part 6: Preparing fertilized zebrafish embryos for microinjection
<ol>
	<li>Zebrafish will randomly mate in the first few hours of each morning. Collect embryos at the 1-cell stage and place them in 1x E3 medium.</li>
	<li>Using a 3 mL transfer pipet (Becton Dickinson Labware, 357524), arrange the embryos along the wedge-shaped troughs in the microinjection chamber plates.</li>
	<li>Remove the medium so that the embryos are shallowly submerged and not flooded. This step aids in settling the embryos to the bottom of the troughs as well as in the penetration of the chorion by the micropipette.</li>
</ol>
Part 7: Microinjection through the chorion
<ol>
	<li>Manipulate the embryos with the micropipette so that the cytoplasm of the 1-cell stage embryo is visible under the dissecting microscope. Take care not to break the tip of the micropipette.</li>
	<li>Penetrate the chorion and then the yolk with the micropipette in order to inject into the embryo. In this demonstration, we will be first microinjecting into the yolk directly below the cell, and allow cytoplasmic flow and diffusion to bring the working solution into the cell. This flow is visible due to the phenol red added to the working solution.</li>
	<li>We will also demonstrate direct injection into the cell cytoplasm. Direct microinjection into the cell is more robust but time-consuming as proper embryo orientation and microinjection technique is required. As the cell membrane is more rigorous than the yolk membrane, it is often quicker to enter the micropipette through the yolk to reach the cell cytoplasm. Orienting the animal pole towards the bottom of the trough and working with steady hands may aid in this method of injection.</li>
	<li>After microinjection, place the embryos into a Petri dish with E3 medium and incubate them at 28.5&#176;C for normal development.</li>
	<li>Over the next several hours and days of embryo development, observe the embryos for your phenotypes of interest.</li>
</ol>
Part 8: Representative results
EGFP mRNA overexpression: To verify the success of the microinjection, we will monitor the expression of GFP in the developing embryos beginning at shield stage (~6 hpf) by in vivo whole-embryo fluorescence microscopy (Leica Microsystems GmBh, MZFLIII). Expression of the construct is most strong during the early events of embryonic development and will often diminish during development as the injected capped RNA is gradually degraded and depends on the stability of the expressed protein.
pkd2 translational-blocking morpholino: Based on previously published results, we expect the pkd2 morphants to mimic the dorsal body axis curvature as found in pkd2 mutant zebrafish and present kidney cysts at approximately 2 - 3 dpf4.
<img alt="Figure 1" src="/files/ftp_upload/old/1113/1113fig1.jpg" /> 
Figure 1: Representative results from microinjection of EGFP mRNA and pkd2 AUG morpholino. (a) TAB embryos were microinjected at the 1-cell stage with 0.17 ng of EGFP mRNA and visualized at 1 dpf for in vivo GFP expression. (b,c) TAB embryos were microinjected at the 1-cell stage with ~1.7 nl of a pkd2 translational blocking morpholino at 0.50 mM and scored for dorsal body curvature at 4 dpf.

<ol>
	<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). , (2000).</li><li>Nasevicius, A., Ekker, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effective+targeted+gene+'knockdown'+in+zebrafish.">Effective targeted gene 'knockdown' in zebrafish.</a> Nat Genet. 26, 216-220 (2000).</li><li>Draper, B., Morcos, P., Kimmel, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+zebrafish+fgf8+pre-mRNA+splicing+with+morpholino+oligos:+a+quantifiable+method+for+gene+knockdown.">Inhibition of zebrafish fgf8 pre-mRNA splicing with morpholino oligos: a quantifiable method for gene knockdown.</a> Genesis. 30, 154-156 (2001).</li><li>Sun, Z., 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+genetic+screen+in+zebrafish+identifies+cilia+genes+as+a+principal+cause+of+cystic+kidney.">A genetic screen in zebrafish identifies cilia genes as a principal cause of cystic kidney.</a> Development. 131, 4085-4093 (2004).</li><li>Stuart, G., McMurray, J., 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=Replication,+integration+and+stable+germ-line+transmission+of+foreign+sequences+injected+into+early+zebrafish+embryos.">Replication, integration and stable germ-line transmission of foreign sequences injected into early zebrafish embryos.</a> Development. 103, 403-412 (1988).</li><li>Stuart, G., Vielkind, J., McMurray, J., 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=Stable+lines+of+transgenic+zebrafish+exhibit+reproducible+patterns+of+transgene+expression.">Stable lines of transgenic zebrafish exhibit reproducible patterns of transgene expression.</a> Development. 109, 577-584 (1990).</li><li>Culp, P., N&#252;sslein-Volhard, C., Hopkins, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-frequency+germ-line+transmission+of+plasmid+DNA+sequences+injected+into+fertilized+zebrafish+eggs.">High-frequency germ-line transmission of plasmid DNA sequences injected into fertilized zebrafish eggs.</a> Proc Natl Acad Sci U S A. 88, 7953-7957 (1991).</li><li>Strehlow, D., Heinrich, G., Gilbert, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fates+of+the+blastomeres+of+the+16-cell+zebrafish+embryo.">The fates of the blastomeres of the 16-cell zebrafish embryo.</a> Development. 120, 1791-1798 (1994).</li><li>Helde, K., Wilson, E., Cretekos, C., Grunwald, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contribution+of+early+cells+to+the+fate+map+of+the+zebrafish+gastrula.">Contribution of early cells to the fate map of the zebrafish gastrula.</a> Science. 265, 517-520 (1994).</li><li>Lin, S., Long, W., Chen, J., Hopkins, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+germ-line+chimeras+in+zebrafish+by+cell+transplants+from+genetically+pigmented+to+albino+embryos.">Production of germ-line chimeras in zebrafish by cell transplants from genetically pigmented to albino embryos.</a> Proc Natl Acad Sci U S A. 89, 4519-4523 (1992).</li><li>Long, Q., 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=GATA-1+expression+pattern+can+be+recapitulated+in+living+transgenic+zebrafish+using+GFP+reporter+gene.">GATA-1 expression pattern can be recapitulated in living transgenic zebrafish using GFP reporter gene.</a> Development. 124, 4105-4111 (1997).</li><li>Murphey, R., Zon, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+molecule+screening+in+the+zebrafish.">Small molecule screening in the zebrafish.</a> Methods. 39, 255-261 (2006).</li></ol>

Microinjection into zebrafish embryos is a well-established and robust technique for exploring the role of a particular gene in development. Applications include overexpression, misexpression, and knockdown assays of your gene of interest as well as epistatic analysis between multiple genes. Microinjection in zebrafish has been widely used for generating transgenic animals, and mapping cell fate in early blastula embryos5,6,7,8,9. In addition, the application of this technique serves as a key step in generatin...

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<td>1x E3 Medium</td>
<td>Reagent</td>
<td>&nbsp;</td>
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<td>5 mM NaCl 
0.17 mM KCl 
0.33 mM CaCl2 
0.33 mM MgSO2 
0.1% Methylene blue</td>
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			All other materials are listed in the protocol.		</div>

microinjection of mrna and morpholino antisense oligonucleotides in zebrafish embryos.

An essential tool for investigating the role of a gene during development is the ability to perform gene knockdown, overexpression, and misexpression studies. In zebrafish (Danio rerio), microinjection of RNA, DNA, proteins, antisense oligonucleotides and other small molecules into the developing embryo provides researchers a quick and robust assay for exploring gene function in vivo. In this video-article, we will demonstrate how to prepare and microinject in vitro synthesized EGFP mRNA and a translational-blocking morpholino oligo against pkd2, a gene associated with autosomal dominant polycystic kidney disease (ADPKD), into 1-cell stage zebrafish embryos. We will then analyze the success of the mRNA and morpholino microinjections by verifying GFP expression and phenotype analysis. Broad applications of this technique include generating transgenic animals and germ-line chimeras, cell-fate mapping and gene screening. Herein we describe a protocol for overexpression of EGFP and knockdown of pkd2 by mRNA and morpholino oligonucleotide injection.

Watch this Scientific Journal Video about Microinjection of mRNA and Morpholino Antisense Oligonucleotides in Zebrafish Embryos. at JoVE.com

Microinjection of mRNA and Morpholino Antisense Oligonucleotides in Zebrafish Embryos.

Microinjection is a well-established and effective method for introducing foreign substances into fertilized zebrafish embryos. Here, we demonstrate a robust microinjection technique for performing mRNA overexpression, and morpholino oligonucleotide gene knockdown studies in zebrafish.

An essential tool for investigating the role of a gene during development is the ability to perform gene knockdown, overexpression, and misexpression ...

microinjection-mrna-morpholino-antisense-oligonucleotides-zebrafish

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36.6K Views.  Yale University School of Medicine. Microinjection is a well-established and effective method for introducing foreign substances into fertilized zebrafish embryos. Here, we demonstrate a robust microinjection technique for performing mRNA overexpression, and morpholino oligonucleotide gene knockdown studies in zebrafish.

Video: Microinjection of mRNA and Morpholino Antisense Oligonucleotides in Zebrafish Embryos.

Microinjection of A. aegypti Embryos to Obtain Transgenic Mosquitoes

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue fever.  The techniques for correctly preparing microinjection needles, dessicating embryos, and performing microinjection are demonstrated.

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue fever. The techniques for correctly preparing microinjection needles, dessicating embryos, and performing microinjection are demonstrated.

In this video, Nijole Jasinskiene demonstrates the methodology employed to generate transgenic Aedes aegypti mosquitoes, which are vectors for dengue ...

Microinjection of Zebrafish Embryos to Analyze Gene Function

One of the advantages of studying zebrafish is the ease and speed of manipulating protein levels in the embryo.  Morpholinos, which are synthetic oligonucleotides with antisense complementarity to target RNAs, can be added to the embryo to reduce the expression of a particular gene product.  Conversely, processed mRNA can be added to the embryo to increase levels of a gene product.  The vehicle for adding either mRNA or morpholino to an embryo is microinjection.  Microinjection is efficient and rapid, allowing for the injection of hundreds of embryos per hour.  This video shows all the steps involved in microinjection.  Briefly, eggs are collected immediately after being laid and lined up against a microscope slide in a Petri dish.  Next, a fine-tipped needle loaded with injection material is connected to a microinjector and an air source, and the microinjector controls are adjusted to produce a desirable injection volume.  Finally, the needle is plunged into the embryo's yolk and the morpholino or mRNA is expelled.

This video shows how morpholino or mRNA can be injected into zebrafish embryos at the one-cell stage to decrease or increase the level of specific gene products during subsequent development.

One of the advantages of studying zebrafish is the ease and speed of manipulating protein levels in the embryo.  Morpholinos, which are synthetic ...

Two-photon axotomy and time-lapse confocal imaging in live zebrafish embryos

Zebrafish have long been utilized to study the cellular and molecular mechanisms of development by time-lapse imaging of the living transparent embryo. Here we describe a method to mount zebrafish embryos for long-term imaging and demonstrate how to automate the capture of time-lapse images using a confocal microscope. We also describe a method to create controlled, precise damage to individual branches of peripheral sensory axons in zebrafish using the focused power of a femtosecond laser mounted on a two-photon microscope. The parameters for successful two-photon axotomy must be optimized for each microscope. We will demonstrate two-photon axotomy on both a custom built two-photon microscope and a Zeiss 510 confocal/two-photon to provide two examples.

Zebrafish trigeminal sensory neurons can be visualized in a transgenic line expressing GFP driven by a sensory neuron specific promoter 1. We have adapted this zebrafish trigeminal model to directly observe sensory axon regeneration in living zebrafish embryos. Embryos are anesthetized with tricaine and positioned within a drop of agarose as it solidifies. Immobilized embryos are sealed within an imaging chamber filled with phenylthiourea (PTU) Ringers. We have found that embryos can be continuously imaged in these chambers for 12-48 hours. A single confocal image is then captured to determine the desired site of axotomy. The region of interest is located on the two-photon microscope by imaging the sensory axons under low, non-damaging power. After zooming in on the desired site of axotomy, the power is increased and a single scan of that defined region is sufficient to sever the axon. Multiple location time-lapse imaging is then set up on a confocal microscope to directly observe axonal recovery from injury.

Here we describe a method for mounting zebrafish embryos for long-term imaging, two-photon imaging and tissue-damage techniques, and time-lapse confocal imaging.

Zebrafish have long been utilized to study the cellular and molecular mechanisms of development by time-lapse imaging of the living transparent embryo.  ...

Generating Chimeric Zebrafish Embryos by Transplantation

One of the most powerful tools used to gain insight into complex developmental processes is the analysis of chimeric embryos. A chimera is defined as an organism that contains cells from more than one animal; mosaics are one type of chimera in which cells from more than one genotype are mixed, usually wild-type and mutant. In the zebrafish, chimeras can be readily made by transplantation of cells from a donor embryo into a host embryo at the appropriate embryonic stage. Labeled donor cells are generated by injection of a lineage marker, such as a fluorescent dye, into the one-cell stage embryo. Labeled donor cells are removed from donor embryos and introduced into unlabeled host embryos using an oil-controlled glass pipette mounted on either a compound or dissecting microscope. Donor cells can in some cases be targeted to a specific region or tissue of the developing blastula or gastrula stage host embryo by choosing a transplantation site in the host embryo based on well-established fate maps.

A step-by-step guide to generating targeted chimeric zebrafish embryos by transplantation at the blastula or gastrula stage.

One of the most powerful tools used to gain insight into complex developmental processes is the analysis of chimeric embryos. A chimera is defined as an ...

Two-Photon-Based Photoactivation in Live Zebrafish Embryos

Photoactivation of target compounds in a living organism has proven a valuable approach to investigate various biological processes such as embryonic development, cellular signaling and adult physiology. In this respect, the use of multi-photon microscopy enables quantitative photoactivation of a given light responsive agent in deep tissues at a single cell resolution. As zebrafish embryos are optically transparent, their development can be monitored in vivo. These traits make the zebrafish a perfect model organism for controlling the activity of a variety of chemical agents and proteins by focused light. Here we describe the use of two-photon microscopy to induce the activation of chemically caged fluorescein, which in turn allows us to follow cell's destiny in live zebrafish embryos. We use embryos expressing a live genetic landmark (GFP) to locate and precisely target any cells of interest. This procedure can be similarly used for precise light induced activation of proteins, hormones, small molecules and other caged compounds.

Multiphoton microscopy allows control of low energy photons with deep optical penetration and reduced phototoxicity. We describe the use of this technology for live cell labeling in zebrafish embryos. This protocol can be readily adapted for photo-induction of various light-responsive molecules.

Photoactivation of target compounds in a living organism has proven a valuable approach to investigate various biological processes such as embryonic ...

Microinjection of Medaka Embryos for use as a Model Genetic Organism

In this video, we demonstrate the technique of microinjection into one-cell stage medaka embryos. Medaka is a small egg-laying freshwater fish that allows both genetic and embryological analyses and is one of the vertebrate model organisms in which genome-wide phenotype-driven mutant screens were carried out 1, as in zebrafish and the mouse. Divergence of functional overlap of related genes between medaka and zebrafish allows identification of novel phenotypes that are unidentifiable in a single species 2, thus medaka and zebrafish are complementary for genetic dissection of vertebrate genome functions.
To take advantage of medaka fish whose embryos are transparent and develop externally, microinjection is an essential technique to inject cell-tracers for labeling cells, mRNAs or anti-sense oligonucleotides for over-expressing and knocking-down genes of interest, and DNAs for making transgenic lines.

Medaka and zebrafish are complementary for genetic dissection of vertebrate genome functions. This protocol highlights the key points for successful microinjection into medaka embryos, an important technique for embryological and genetic analysis using medaka and zebrafish in a laboratory.

In this video, we demonstrate the technique of microinjection into one-cell stage medaka embryos. Medaka is a small egg-laying freshwater fish that allows ...

Analysis of mRNA Nuclear Export Kinetics in Mammalian Cells by Microinjection

In eukaryotes, messenger RNA (mRNA) is transcribed in the nucleus and must be exported into the cytoplasm to access the translation machinery. Although the nuclear export of mRNA has been studied extensively in Xenopus oocytes1 and genetically tractable organisms such as yeast2 and the Drosophila derived S2 cell line3, few studies had been conducted in mammalian cells. Furthermore the kinetics of mRNA export in mammalian somatic cells could only be inferred indirectly4,5. In order to measure the nuclear export kinetics of mRNA in mammalian tissue culture cells, we have developed an assay that employs the power of microinjection coupled with fluorescent in situ hybridization (FISH). These assays have been used to demonstrate that in mammalian cells, the majority of mRNAs are exported in a splicing dependent manner6,7, or in manner that requires specific RNA sequences such as the signal sequence coding region (SSCR) 6. In this assay, cells are microinjected with either in vitro synthesized mRNA or plasmid DNA containing the gene of interest. The microinjected cells are incubated for various time points then fixed and the sub-cellular localization of RNA is assessed using FISH. In contrast to transfection, where transcription occurs several hours after the addition of nucleic acids, microinjection of DNA or mRNA allows for rapid expression and allows for the generation of precise kinetic data.

Here we describe an assay that employs the power of microinjection coupled with fluorescent in situ hybridization in order to accurately measure the nuclear export kinetics of mRNA in mammalian somatic cells.

In eukaryotes, messenger RNA (mRNA) is transcribed in the nucleus and must be exported into the cytoplasm to access the translation machinery. Although ...

Imaging Glycans in Zebrafish Embryos by Metabolic Labeling and Bioorthogonal Click Chemistry

Imaging glycans in vivo has recently been enabled using a bioorthogonal chemical reporter strategy by treating cells or organisms with azide- or alkyne-tagged monosaccharides1, 2. The modified monosaccharides, processed by the glycan biosynthetic machinery, are incorporated into cell surface glycoconjugates. The bioorthogonal azide or alkyne tags then allow covalent conjugation with fluorescent probes for visualization, or with affinity probes for enrichment and glycoproteomic analysis. This protocol describes the procedures typically used for noninvasive imaging of fucosylated glycans in zebrafish embryos, including: 1) microinjection of one-cell stage embryos with GDP-5-alkynylfucose (GDP-FucAl), 2) labeling fucosylated glycans in the enveloping layer of zebrafish embryos with azide-conjugated fluorophores via biocompatible Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC), and 3) imaging by confocal microscopy3. The method described here can be readily extended to visualize other classes of glycans, e.g. glycans containing sialic acid4 and N-acetylgalactosamine5, 6, in developing zebrafish and in other living organisms.

A click-chemistry based method that allows for the rapid, noninvasive, and robust labeling of alkyne-tagged glycans in zebrafish embryos is described. Fucosylated glycans in the enveloping layer of zebrafish embryos in the late gastrulation stage were imaged in this study.

Imaging glycans in vivo has recently been enabled using a bioorthogonal chemical reporter strategy by treating cells or organisms with azide- or ...

Metabolic Profile Analysis of Zebrafish Embryos

A growing goal in the field of metabolism is to determine the impact of genetics on different aspects of mitochondrial function. Understanding these relationships will help to understand the underlying etiology for a range of diseases linked with mitochondrial dysfunction, such as diabetes and obesity. Recent advances in instrumentation, has enabled the monitoring of distinct parameters of mitochondrial function in cell lines or tissue explants. Here we present a method for a rapid and sensitive analysis of mitochondrial function parameters in vivo during zebrafish embryonic development using the Seahorse bioscience XF 24 extracellular flux analyser. This protocol utilizes the Islet Capture microplates where a single embryo is placed in each well, allowing measurement of bioenergetics, including: (i) basal respiration; (ii) basal mitochondrial respiration (iii) mitochondrial respiration due to ATP turnover; (iv) mitochondrial uncoupled respiration or proton leak and (iv) maximum respiration. Using this approach embryonic zebrafish respiration parameters can be compared between wild type and genetically altered embryos (mutant, gene over-expression or gene knockdown) or those manipulated pharmacologically. It is anticipated that dissemination of this protocol will provide researchers with new tools to analyse the genetic basis of metabolic disorders in vivo in this relevant vertebrate animal model.

Zebrafish represent a powerful vertebrate model that has been under-utilised for metabolic studies. Here we describe a rapid way to measure the in vivo metabolic profile of developing zebrafish that allows the comparison of different mitochondrial function parameters between genetically or pharmacologically manipulated embryos, thereby increasing the applicability of this organism.

A growing goal in the field of metabolism is to determine the impact of genetics on different aspects of mitochondrial function. Understanding these ...

Analysis of Oxidative Stress in Zebrafish Embryos

High levels of reactive oxygen species (ROS) may cause a change of cellular redox state towards oxidative stress condition. This situation causes oxidation of molecules (lipid, DNA, protein) and leads to cell death. Oxidative stress also impacts the progression of several pathological conditions such as diabetes, retinopathies, neurodegeneration, and cancer. Thus, it is important to define tools to investigate oxidative stress conditions not only at the level of single cells but also in the context of whole organisms. Here, we consider the zebrafish embryo as a useful in vivo system to perform such studies and present a protocol to measure in vivo oxidative stress. Taking advantage of fluorescent ROS probes and zebrafish transgenic fluorescent lines, we develop two different methods to measure oxidative stress in vivo: i) a &#8220;whole embryo ROS-detection method&#8221; for qualitative measurement of oxidative stress and ii) a &#8220;single-cell&#160;ROS detection method&#8221; for quantitative measurements of oxidative stress. Herein, we demonstrate the efficacy of these procedures by increasing oxidative stress in tissues by oxidant agents and physiological or genetic methods. This protocol is amenable for forward genetic screens and it will help address cause-effect relationships of ROS in animal models of oxidative stress-related pathologies such as neurological disorders and cancer.

Here we report a protocol to measure oxidative stress in living zebrafish embryos. This procedure allows reactive oxygen species (ROS) detection in both whole embryo tissues and single-cell populations. This protocol will accomplish both qualitative and quantitative analyses.