We thank David Huss for helpful insights into this work. This work was supported in part by the Rose Hills Foundation Summer Research Fellowship (2016-2018) and USC Provost&#8217;s Undergrad Research Fellowship to M.T., the Saban Research Institute Intramural Training Pre-Doctoral Award to M.D., and the University of Southern California Undergraduate Research Associates Program award to R.L.

<ol>
	<li>Neumann, E., Schaefer-Ridder, M., Wang, Y., Hofschneider, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+transfer+into+mouse+lyoma+cells+by+electroporation+in+high+electric+fields.">Gene transfer into mouse lyoma cells by electroporation in high electric fields.</a> EMBO Journal. 1 (7), 841-845 (1982).</li><li>Potter, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroporation+in+biology:+methods,+applications,+and+instrumentation.">Electroporation in biology: methods, applications, and instrumentation.</a> Analytical Biochemistry. 174 (2), 361-373 (1988).</li><li>Shillito, R. D., Saul, M. W., Paszkowski, J., Muller, M., Potrykus, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Efficiency+Direct+Gene-Transfer+to+Plants.">High-Efficiency Direct Gene-Transfer to Plants.</a> Bio-Technology. 3 (12), 1099-1103 (1985).</li><li>Cui, C., Rongish, B., Little, C., Lansford, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ex+Ovo+Electroporation+of+DNA+Vectors+into+Pre-gastrulation+Avian+Embryos.">Ex Ovo Electroporation of DNA Vectors into Pre-gastrulation Avian Embryos.</a> CSH Protocol. 2007 (24), 4894 (2007).</li><li>Voiculescu, O., Papanayotou, C., Stern, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatially+and+temporally+controlled+electroporation+of+early+chick+embryos.">Spatially and temporally controlled electroporation of early chick embryos.</a> Nature Protocol. 3 (3), 419-426 (2008).</li><li>Voiculescu, O., Stern, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manipulating+Gene+Expression+in+the+Chick+Embryo.">Manipulating Gene Expression in the Chick Embryo.</a> Methods Molecular Biology. , 105-114 (2017).</li><li>Chuai, M., 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=Cell+movement+during+chick+primitive+streak+formation.">Cell movement during chick primitive streak formation.</a> Developmental Bioliogy. 296 (1), 137-149 (2006).</li><li>Krull, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+primer+on+using+in+ovo+electroporation+to+analyze+gene+function.">A primer on using in ovo electroporation to analyze gene function.</a> Developmental Dynamics. 229 (3), 433-439 (2004).</li><li>Momose, T., 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=Efficient+targeting+of+gene+expression+in+chick+embryos+by+microelectroporation.">Efficient targeting of gene expression in chick embryos by microelectroporation.</a> Developmental, Growth and Differentiation. 41 (3), 335-344 (1999).</li><li>Nakamura, H., Watanabe, Y., Funahashi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Misexpression+of+genes+in+brain+vesicles+by+in+ovo+electroporation.">Misexpression of genes in brain vesicles by in ovo electroporation.</a> Developmental, Growth and Differentiation. 42 (3), 199-201 (2000).</li><li>Teddy, J. M., Lansford, R., Kulesa, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Four-color,+4-D+time-lapse+confocal+imaging+of+chick+embryos.">Four-color, 4-D time-lapse confocal imaging of chick embryos.</a> Biotechniques. 39 (5), 703-710 (2005).</li><li>Green, M. R., Maniatis, T., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+beta-globin+pre-mRNA+synthesized+in+vitro+is+accurately+spliced+in+Xenopus+oocyte+nuclei.">Human beta-globin pre-mRNA synthesized in vitro is accurately spliced in Xenopus oocyte nuclei.</a> Cell. 32 (3), 681-694 (1983).</li><li>Mimoto, M. S., Christian, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manipulation+of+gene+function+in+Xenopus+laevis.">Manipulation of gene function in Xenopus laevis.</a> Methods in Molecular Biology. 770, 55-75 (2011).</li><li>Luni, 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=High-efficiency+cellular+reprogramming+with+microfluidics.">High-efficiency cellular reprogramming with microfluidics.</a> Nature Methods. 13 (5), 446-452 (2016).</li><li>Bugeon, S., 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=Direct+and+efficient+transfection+of+mouse+neural+stem+cells+and+mature+neurons+by+in+vivo+mRNA+electroporation.">Direct and efficient transfection of mouse neural stem cells and mature neurons by in vivo mRNA electroporation.</a> Development. 144 (21), 3968-3977 (2017).</li><li>Riedl, J., 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=Lifeact:+a+versatile+marker+to+visualize+F-actin.">Lifeact: a versatile marker to visualize F-actin.</a> Nature Methods. 5 (7), 605-607 (2008).</li><li>Turner, D. 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=Expression+of+achaete-scute+homolog+3+in+Xenopus+embryos+converts+ectodermal+cells+to+a+neural+fate.">Expression of achaete-scute homolog 3 in Xenopus embryos converts ectodermal cells to a neural fate.</a> Genes and Development. 8 (12), 1434-1447 (1994).</li><li>Krieg, P. A., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+messenger+RNAs+are+produced+by+SP6+in+vitro+transcription+of+cloned+cDNAs.">Functional messenger RNAs are produced by SP6 in vitro transcription of cloned cDNAs.</a> Nucleic Acids Research. 12 (18), 7057-7070 (1984).</li><li>Hamburger, V., Hamilton, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+series+of+normal+stages+in+the+development+of+the+chick+embryo.">A series of normal stages in the development of the chick embryo.</a> Journal of Morphology. 88 (1), 49-92 (1951).</li><li>Eyal-Giladi, H., Kochav, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+cleavage+to+primitive+streak+formation:+a+complementary+normal+table+and+a+new+look+at+the+first+stage+of+the+development+of+the+chick.+I.+General+morphology.">From cleavage to primitive streak formation: a complementary normal table and a new look at the first stage of the development of the chick. I. General morphology.</a> Developmental Biology. 49, 321-337 (1976).</li><li>Ainsworth, S. J., Stanley, R. L., Evans, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental+stages+of+the+Japanese+quail.">Developmental stages of the Japanese quail.</a> Journal of Anatomy. 216 (1), 3-15 (2010).</li><li>Chapman, S. C., Collignon, J., Schoenwolf, G. C., Lumsden, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+method+for+chick+whole-embryo+culture+using+a+filter+paper+carrier.">Improved method for chick whole-embryo culture using a filter paper carrier.</a> Developmental Dynamics. 220 (3), 284-289 (2001).</li><li>Hama, H., 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=Scale:+a+chemical+approach+for+fluorescence+imaging+and+reconstruction+of+transparent+mouse+brain.">Scale: a chemical approach for fluorescence imaging and reconstruction of transparent mouse brain.</a> Nature Neurosciences. 14 (11), 1481-1488 (2011).</li><li>New, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+technique+for+the+cultivation+of+the+chick+embryo+in+vitro.">A new technique for the cultivation of the chick embryo in vitro.</a> Journal of Embryology and Experimental Morphology. 3, 320-331 (1955).</li><li>Drake, C. J., Davis, L. A., Hungerford, J. E., Little, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perturbation+of+beta+1+integrin-mediated+adhesions+results+in+altered+somite+cell+shape+and+behavior.">Perturbation of beta 1 integrin-mediated adhesions results in altered somite cell shape and behavior.</a> Developmental Biology. 149 (2), 327-338 (1992).</li><li>Sato, Y., 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=Dynamic+analysis+of+vascular+morphogenesis+using+transgenic+quail+embryos.">Dynamic analysis of vascular morphogenesis using transgenic quail embryos.</a> PLoS ONE. 5 (9), e12674 (2010).</li><li>Kanda, T., Sullivan, K. F., Wahl, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histone-GFP+fusion+protein+enables+sensitive+analysis+of+chromosome+dynamics+in+living+mammalian+cells.">Histone-GFP fusion protein enables sensitive analysis of chromosome dynamics in living mammalian cells.</a> Current Biology. 8 (7), 377-385 (1998).</li><li>Uetrecht, A. C., Bear, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Golgi+polarity+does+not+correlate+with+speed+or+persistence+of+freely+migrating+fibroblasts.">Golgi polarity does not correlate with speed or persistence of freely migrating fibroblasts.</a> European Journal of Cell Biology. 88 (12), 711-717 (2009).</li><li>Alberts, B., 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> Molecular Biology of the Cell. , (2007).</li><li>Arndt-Jovin, D. J., Jovin, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence+labeling+and+microscopy+of+DNA.">Fluorescence labeling and microscopy of DNA.</a> Methods Cell Biol. 30, 417-448 (1989).</li><li>Jovin, T. M., Arndt-Jovin, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Luminescence+digital+imaging+microscopy.">Luminescence digital imaging microscopy.</a> Annu Rev Biophysics and Biophysical Chemistry. 18, 271-308 (1989).</li><li>Heikal, A. A., Hess, S. T., Baird, G. S., Tsien, R. Y., Webb, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+spectroscopy+and+dynamics+of+intrinsically+fluorescent+proteins:+coral+red+(dsRed)+and+yellow+(Citrine).">Molecular spectroscopy and dynamics of intrinsically fluorescent proteins: coral red (dsRed) and yellow (Citrine).</a> Proceedings of the National Academy of Science U S A. 97 (22), 11996-12001 (2000).</li><li>Iizuka, R., Yamagishi-Shirasaki, M., Funatsu, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+study+of+de+novo+chromophore+maturation+of+fluorescent+proteins.">Kinetic study of de novo chromophore maturation of fluorescent proteins.</a> Analytical Biochemistry. 414 (2), 173-178 (2011).</li><li>Nakamura, H., Katahira, T., Sato, T., Watanabe, Y., Funahashi, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gain-+and+loss-of-function+in+chick+embryos+by+electroporation.">Gain- and loss-of-function in chick embryos by electroporation.</a> Mechanism of Development. 121 (9), 1137-1143 (2004).</li><li>Swartz, M., Eberhart, J., Mastick, G. S., Krull, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sparking+new+frontiers:+using+in+vivo+electroporation+for+genetic+manipulations.">Sparking new frontiers: using in vivo electroporation for genetic manipulations.</a> Developmental Biology. 233 (1), 13-21 (2001).</li><li>Meyer, S., Temme, C., Wahle, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Messenger+RNA+turnover+in+eukaryotes:+pathways+and+enzymes.">Messenger RNA turnover in eukaryotes: pathways and enzymes.</a> Critical Reviews in Biochemistry and Molecular Biology. 39 (4), 197-216 (2004).</li><li>Bevilacqua, P. C., Ritchey, L. E., Su, Z., Assmann, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome-Wide+Analysis+of+RNA+Secondary+Structure.">Genome-Wide Analysis of RNA Secondary Structure.</a> Annual Review in Genetics. 50, 235-266 (2016).</li><li>Harland, R., Misher, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stability+of+RNA+in+developing+Xenopus+embryos+and+identification+of+a+destabilizing+sequence+in+TFIIIA+messenger+RNA.">Stability of RNA in developing Xenopus embryos and identification of a destabilizing sequence in TFIIIA messenger RNA.</a> Development. 102 (4), 837-852 (1988).</li><li>Lippincott-Schwartz, 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+long+road:+peering+into+live+cells.">The long road: peering into live cells.</a> Nature Cell Biology. 12 (10), 918 (2010).</li><li>Sato, Y., Lansford, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transgenesis+and+imaging+in+birds,+and+available+transgenic+reporter+lines.">Transgenesis and imaging in birds, and available transgenic reporter lines.</a> Development Growth &amp; Differentiation. 55 (4), 406-421 (2013).</li><li>Goldman, R. D., Spector, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Live Cell Imaging: A Laboratory Manual. , (2005).</li></ol>

The authors have no conflicts of interest to declare.

In this protocol, we provided step by step instructions on how to precisely microinject and electroporate mRNA into the cells of gastrulating quail embryos. We demonstrated that in vitro synthesized mRNA electroporation allows fast and efficient expression of fluorescent proteins (FPs) in gastrulating quail embryos (Figure 2 and 3). Fluorescence from H2B-citrine protein translated from electroporated mRNAs could be detected by confocal microscopy within ~20 min and increased...

Electroporation is a physical transfection method that uses an electrical pulse to create transient pores in the plasma membrane, allowing substances like nucleic acids or chemicals to pass into the cytosol. Electroporation is widely used to deliver DNA into bacteria, yeast, plants, and mammalian cells1,2,3. It is routinely used to introduce genetic payloads into target cells and tissues within the developing avian embryo to study the genetic control of development or label migrating populations of cells4,5,6,7. However, several experimental limitations also exist with DNA electroporation8. For instance, DNA electroporation often introduces highly variable numbers of expression vectors per cell and subsequently the mRNAs and proteins they encode. This variability can lead to considerable cell-cell heterogeneity that complicates both image analysis and data interpretation9,10. Additionally, proteins from DNA electroporation only begin to express ~3 h post-electroporation and do not reach the maximum efficiency in cell number and fluorescence intensity until 12 h, likely due to the time required to transfer into the nucleus and complete both transcription and translation in vivo11.
In contrast, mRNA transfection has been effectively used in a variety of model systems, including Xenopus laevis oocytes by microinjection12,13, reprogramming human stem cells by mRNA lipofectamine transfection14, and electroporating recalcitrant neural stem cells in adult mice15. We tested the ability of mRNA electroporation to efficiently label cells during early avian embryonic development using in vitro synthesized mRNAs that encode distinct fluorescent proteins (FPs). For our studies, we used the pCS2+ vector, a multipurpose expression vector that is commonly used for expressing proteins in Xenopus and zebrafish embryos. The SP6 and T7 RNA polymerase promoters in the pCS2+ permit the synthesis of mRNA and protein&#160;from any cloned gene when used in an&#160;in vitro&#160;transcription/translation system.
Here, we demonstrate that mRNA electroporation allows fast and efficient expression of fluorescent proteins (FPs) in gastrulating quail embryos. We designed and generated many of the expression vectors used in these studies. For example, we subcloned the LifeAct-eGFP gene16 into the pCS2+ vector17 to express from the CMV promoter and SP6 promoter. The inserted gene lies downstream of the SP6 promoter and upstream of the SV40 poly(A) tail18. In embryos co-electroporated with mRNA and DNA, FPs encoded from in vitro transcribed mRNAs were first detected within 20 min of electroporation, whereas FPs from DNA expression vectors were detected only after 3 h. Multiple mRNAs encoding for nuclear, Golgi, and membrane proteins can be electroporated into an embryo simultaneously, resulting in the quick and efficient expression of multiple proteins in individual cells. Finally, using an in vivo fluorescence recovery after photobleaching (FRAP) assay, we show that a majority of the electroporated mRNAs decay within 2 h. Thus, fast initial protein production combined with limited new protein translation makes mRNA electroporation a valuable technique when temporal control of expression is necessary.

<table><tbody><tr><td>BamHI-HF</td><td>New England Biolabs</td><td>R3136L</td><td></td></tr><tr><td>BglII</td><td>New England Biolabs</td><td>R0144S</td><td></td></tr><tr><td>BsrG1-HF</td><td>New England Biolabs</td><td>R3575S</td><td></td></tr><tr><td>NotI-HF</td><td>New England Biolabs</td><td>R3189L</td><td></td></tr><tr><td>SalI-HF</td><td>New England Biolabs</td><td>R3138L</td><td></td></tr><tr><td>Phenol:Chloroform:Isoamyl Alcohol</td><td>Thermo Fisher</td><td>15593031</td><td></td></tr><tr><td>SP6 mMessage Machine in vitro transcription kit</td><td>Thermo Fisher</td><td>AM1340</td><td></td></tr><tr><td>Fast Green FCF</td><td>Sigma Aldrich</td><td>F7252</td><td></td></tr><tr><td>Triton X-100</td><td>Sigma Aldrich</td><td>93443</td><td>4-(1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol, &lt;em&gt;t&lt;/em&gt;-Octylphenoxypolyethoxyethanol, Polyethylene glycol &lt;em&gt;tert&lt;/em&gt;-octylphenyl ether</td></tr><tr><td>DAPI</td><td>Sigma Aldrich</td><td>D9542</td><td>2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride, 4&amp;prime;,6-Diamidino-2-phenylindole dihydrochloride, DAPI dihydrochloride</td></tr><tr><td>Whatman No.1 filter paper</td><td>Sigma Aldrich</td><td>WHA1001125</td><td></td></tr><tr><td>glycerol</td><td>Sigma Aldrich</td><td>G9012</td><td></td></tr><tr><td>Urea</td><td>Sigma Aldrich</td><td>51457</td><td></td></tr><tr><td>pmTurquoise2-Golgi</td><td>Addgene</td><td>36205</td><td>pmTurquoise2-Golgi was a gift from Dorus Gadella (Addgene plasmid # 36205 ; http://n2t.net/addgene:36205 ; RRID:Addgene_36205)</td></tr><tr><td>pmEGFP-N1-LifeAct</td><td></td><td></td><td>Nat. Methods 2008;5:605-7. PubMed ID: 18536722</td></tr><tr><td>pCS2.Lifeact-mGFP</td><td>Addgene</td><td></td><td>This paper</td></tr><tr><td>pCS.H2B-citrine</td><td>Addgene</td><td>53752</td><td>pCS-H2B-citrine was a gift from Sean Megason (Addgene plasmid # 53752 ; http://n2t.net/addgene:53752 ; RRID:Addgene_53752)</td></tr><tr><td>pCS.memb-mCherry</td><td>Addgene</td><td>#53750</td><td>pCS-memb-mCherry was a gift from Sean Megason (Addgene plasmid # 53750 ; http://n2t.net/addgene:53750 ; RRID:Addgene_53750)</td></tr><tr><td>Zeiss LSM-780 inverted microscope</td><td>Carl Zeiss Microscopy GmbH</td><td></td><td>The LSM-780 is a confocal and multi-photon microscope that offers the sensitivity required for vital imaging work. Equipped with a motorized stage, an autofocus device, and a full stage-top blackout incubator, the 780 is an excellent microscope for high-end live cell/embryo imaging. The high-sensitivity 32-channel Quasar detector allows for spectral imaging, linear unmixing, and high color count (&gt;4) image acquisition. Excitation can be performed with 6 lines single photon lasers (405, 458, 488, 514, 564 and 633 nm), Chameleon (Coherent) 2-photon laser (range from 690nm to 1000nm), and run with ZEN 2011 SP7 (Black) system software.</td></tr><tr><td>CUY-21 EDIT in vivo electroporator</td><td>Bex Co., Ltd.</td><td></td><td></td></tr><tr><td>Platinum flat square electrode, side length 5 mm</td><td>Bex Co., Ltd.</td><td>LF701P5E</td><td></td></tr><tr><td>Olympus MVX10 FL Stereo Microscope</td><td>Olympus LifeScience</td><td></td><td></td></tr><tr><td>XM10 Monochrome camera</td><td>Olympus LifeScience</td><td></td><td></td></tr><tr><td>&lt;strong&gt;Phosphate-Buffered Saline (PBS) for HCR (10&amp;times;, pH 7.4) &lt;/strong&gt;</td><td></td><td></td><td>To prepare 1 L of a 10&amp;times; stock solution, combine 80 g of NaCl (Sigma-Aldrich S3014), 2 g of KCl (Sigma-Aldrich P9541), 11.4 g of Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4 &lt;/sub&gt;(anhydrous; Sigma-Aldrich S3264), and 2.7 g of KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4 &lt;/sub&gt;(anhydrous; Sigma-Aldrich P9791). Adjust the pH to 7.4 with HCl, and bring the final volume to 1 L with ultrapure H2O. Avoid using CaCl2 and MgCl2 in PBS for HCR. It is important that the PBS for HCR is prepared as an RNase-free solution (e.g., via diethylpyrocarbonate [DEPC] treatment).</td></tr><tr><td>1.37 M NaCl</td><td></td><td></td><td></td></tr><tr><td>27 mM KCl</td><td></td><td></td><td></td></tr><tr><td>80 mM Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt; 20 mM KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;</td><td></td><td></td><td></td></tr><tr><td>&lt;strong&gt;PBS/Triton&lt;/strong&gt;</td><td></td><td></td><td>Add 1 mL of Triton X-100 (Sigma Aldrich 93443) and 100 mL of 10&amp;times; PBS to 890 mL of ultrapure distilled H&lt;sub&gt;2&lt;/sub&gt;O. Filter the solution through a 0.2 &amp;mu;m filter and store it at 4 ?C until use.</td></tr><tr><td>1&amp;times; phosphate-buffered saline (PBS) (DEPC-treated; pH 7.4)</td><td></td><td></td><td></td></tr><tr><td>0.1% Triton X-100</td><td></td><td></td><td></td></tr></tbody></table>

fast and efficient expression of multiple proteins in avian embryos using mrna electroporation

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. The high transfection efficiency permits at least 4 distinct mRNAs to be co-transfected with ~87% efficiency. Most of the electroporated mRNAs are degraded during the first 2 h post-electroporation, permitting time-sensitive experiments to be carried out in the developing embryo. Finally, we describe how to dynamically image live embryos electroporated with mRNAs that encode various subcellular targeted fluorescent proteins.

mRNA electroporation is more efficient than DNA electroporation
We used pCS2+.H2B-Citrine to prepare in vitro transcribed mRNA. Since DNA electroporation is usually performed at 1-2 &#181;g/&#181;L, we used an equimolar concentration of mRNA (calculated to be around 0.25-0.5 &#181;g/&#181;L for H2B-Citrine) for mRNA electroporation. We first tested the electroporation efficiency of pCS2+.H2B-Citrine DNA compared...

Watch this Scientific Journal Video about Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation at JoVE.com

Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation

We report messenger RNA (mRNA) electroporation as a method that permits fast and efficient expression of multiple proteins in the quail embryo model system. This method can be used to fluorescently label cells and record their in vivo movements by time-lapse microscopy shortly after electroporation.

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. ...

fast-efficient-expression-multiple-proteins-avian-embryos-using-mrna

Research

JoVE Journal

Developmental Biology

7.1K Views.  University of Southern California, Los Angeles. mRNA-elektroporatie zorgt voor een snelle, efficiënte en ruimtelijk en tijdelijk gecontroleerde expressie van meerdere eiwitten binnen het vogelmodelsysteem. Deze methode zorgt voor een bredere en snellere expressie van fluorescerende eiwitten dan de etikettering bereikt door standaard DNA-elektroporatie. Elektroporatie vergemakkelijkt de tijdelijke opening van poriën in het plasmamembraan die dienen als leidingen voor de overdracht van genetische ladingen zoals RNA en DNA in de cellen van ...

Video: Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2&#180;-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr&#160;after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

The auditory organ mediates hearing. Here we present a modified in ovo micro-electroporation method optimized for studying auditory progenitor cell proliferation and differentiation in the developing chicken auditory organ.

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. ...

In Ovo Electroporations of HH Stage 10 Chicken Embryos

Large size and external development of the chicken embryo have long made it a valuable tool in the study of developmental biology.  With the advent of molecular biological techniques, the chick has become a useful system in which to study gene regulation and function.  By electroporating DNA or RNA constructs into the developing chicken embryo, genes can be expressed or knocked down in order to analyze in vivo gene function.  Similarly, reporter constructs can be used for fate mapping or to examine putative gene regulatory elements.  Compared to similar experiments in mouse, chick electroporation has the advantages of being quick, easy and inexpensive.  This video demonstrates first how to make a window in the eggshell to manipulate the embryo.  Next, the embryo is visualized with a dilute solution of India ink injected below the embryo.  A glass needle and pipette are used to inject DNA and Fast Green dye into the developing neural tube, then platinum electrodes are placed parallel to the embryo and short electrical pulses are administered with a pulse generator.  Finally, the egg is sealed with tape and placed back into an incubator for further development.  Additionally, the video shows proper egg storage and handling and discusses possible causes of embryo loss following electroporation.

Chick in ovo electroporation is a technique which allows genetic manipulation of the avian embryo. Common applications of this technique include functional analysis of genes and putative enhancer elements. This video demonstrates neural tube electroporation in HH 10 chick embryos. Injection technique and proper egg handling are discussed.

Large size and external development of the chicken embryo have long made it a valuable tool in the study of developmental biology.  With the advent of ...

Biology

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms1-3. The dysfunction of ventral midbrain dopaminergic neurons is implicated in Parkinson's disease, Schizophrenia, depression, and dementia1-5. Thus, studying the regulation of midbrain dopaminergic neuron differentiation could not only provide important insight into mechanisms regulating midbrain development and neural progenitor fate specification, but also help develop new therapeutic strategies for treating a variety of human neurological disorders.
Dopaminergic neurons differentiate from neural progenitors lining the ventricular zone of embryonic ventral midbrain. The development of neural progenitors is controlled by gene expression programs6,7. Here we report techniques utilizing electroporation to express genes specifically in the midbrain of Hamburger Hamilton (HH) stage 11 (thirteen somites, 42 hours) chick embryos8,9. The external development of chick embryos allows for convenient experimental manipulations at specific embryonic stages, with the effects determined at later developmental time points10-13. Chick embryonic neural tubes earlier than HH stage 13 (nineteen somites, 48 hours) consist of multipotent neural progenitors that are capable of differentiating into distinct cell types of the nervous system. The pCAG vector, which contains both a CMV promoter and a chick &beta;-actin enhancer, allows for robust expression of Flag or other epitope-tagged constructs in embryonic chick neural tubes14. In this report, we emphasize special measures to achieve regionally restricted gene expression in embryonic midbrain dopaminergic neuron progenitors, including how to inject DNA constructs specifically into the embryonic midbrain region and how to pinpoint electroporation with small custom-made electrodes. Analyzing chick midbrain at later stages provides an excellent in vivo system for plasmid vector-mediated gain-of-function and loss-of-function studies of midbrain development. Modification of the experimental system may extend the assay to other parts of the nervous system for performing fate mapping analysis and for investigating the regulation of gene expression.

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

To assess the function and the regulation of genes during the development of midbrain dopaminergic neurons, we describe a method that involves in ovo electroporation of plasmid DNA constructs into embryonic chick ventral midbrain dopaminergic neuron progenitors. This technique can be used to achieve efficient expression of genes of interest to study different aspects of midbrain development and dopaminergic neuron differentiation.

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms1-3. The dysfunction of ventral midbrain ...

Neuroscience

In ovo Expression of MicroRNA in Ventral Chick Midbrain

Non-coding RNAs are additional players in regulating gene expression. Targeted in ovo electroporation of specific areas provides a unique tool for spatial and temporal control of ectopic microRNA expression. However, ventral brain structures like ventral midbrain are rather difficult to reach for any manipulations. Here, we demonstrate an efficient way to electroporate miRNA into ventral midbrain using thin platinum electrodes. This method offers a reliable way to transfect specific areas of the midbrain and a useful tool for in vivo studies.

In ovo Expression of MicroRNA in Ventral Chick Midbrain

Ectopic expression is one technique to elucidate the microRNAs role in brain development. However, targeting specific areas using in ovo electroporation is challenging. Here, we show an efficient way to selectively electroporate ventral and dorsal midbrain regions.

Non-coding RNAs are additional players in regulating gene expression. Targeted in ovo electroporation of specific areas provides a unique tool for spatial ...

RNA-Seq Analysis of Differential Gene Expression in Electroporated Chick Embryonic Spinal Cord

In ovo electroporation of the chick neural tube is a fast and inexpensive method for identification of gene function during neural development. Genome wide analysis of differentially expressed transcripts after such an experimental manipulation has the potential to uncover an almost complete picture of the downstream effects caused by the transfected construct. This work describes a simple method for comparing transcriptomes from samples of transfected embryonic spinal cords comprising all steps between electroporation and identification of differentially expressed transcripts. The first stage consists of guidelines for electroporation and instructions for dissection of transfected spinal cord halves from HH23 embryos in ribonuclease-free environment and extraction of high-quality RNA samples suitable for transcriptome sequencing. The next stage is that of bioinformatic analysis with general guidelines for filtering and comparison of RNA-Seq datasets in the Galaxy public server, which eliminates the need of a local computational structure for small to medium scale experiments. The representative results show that the dissection methods generate high quality RNA samples and that the transcriptomes obtained from two control samples are essentially the same, an important requirement for detection of differential expression genes in experimental samples. Furthermore, one example is provided where experimental overexpression of a DNA construct can be visually verified after comparison with control samples. The application of this method may be a powerful tool to facilitate new discoveries on the function of neural factors involved in spinal cord early development.

This video shows the basic steps for performing whole transcriptome analysis on dissected chick embryonic spinal cord samples after transfection with in ovo electroporation.

In ovo electroporation of the chick neural tube is a fast and inexpensive method for identification of gene function during neural development. Genome ...

Single Cell Transfection in Chick Embryos

A central theme in developmental biology is the diversification of lineages and the elucidation of underlying molecular mechanisms. This entails a thorough analysis of the fates of single cells under normal and experimental conditions. To this end, transfection methods that target single progenitors are a prerequisite. We describe here a technically straightforward method for transfecting single cells in chicken tissues in-ovo, allowing reliable lineage tracing as well as genetic manipulation. Specific tissue domains are targeted within the somite or neural tube, and DNA is injected directly into the epithelium of interest, resulting in sporadic transfection of single cells. Using reporters, clonal populations may consequently be traced for up to three days, and behavior of genetically manipulated clonal populations can be compared with that of controls. This method takes advantage of the accessibility of the chick embryo along with emerging tools for genetic manipulation. We compare and discuss its advantages over the widely-used electroporation method, and possible applications and use in additional in-vivo models are also suggested. We advocate the use of this method as a significant addition and complement for existing lineage tracing and genetic interference tools.

Using fine tip micropipettes we inject plasmid DNA into subdomains of chicken somites or neural tubes. The concentration of the plasmid is adjusted to generate single transfected cells. We then allow the cells to develop into clonal populations.

A central theme in developmental biology is the diversification of lineages and the elucidation of underlying molecular mechanisms. This entails a ...

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

The inner ear perceives sound and maintains balance using the cochlea and vestibule. It does this by using a dedicated mechanosensory cell type known as the hair cell. Basic research in the inner ear has led to a deep understanding of how the hair cell functions, and how dysregulation can lead to hearing loss and vertigo. For this research, the mouse has been the pre-eminent model system. However, mice, like all mammals, have lost the ability to replace hair cells. Thus, when trying to understand cellular therapies for restoring inner ear function, complementary studies in other vertebrate species could provide further insights. The auditory epithelium of birds, the basilar papilla (BP), is a sheet of epithelium composed of mechanosensory hair cells (HCs) intercalated by supporting cells (SCs). Although the anatomical architecture of the basilar papilla and the mammalian cochlea differ, the molecular mechanisms of inner ear development and hearing are similar. This makes the basilar papilla a useful system for not only comparative studies but also to understand regeneration. Here, we describe dissection and manipulation techniques for the chicken inner ear. The technique shows genetic and small molecule inhibition methods, which offer a potent tool for studying the molecular mechanisms of inner ear development. In this paper, we discuss in ovo electroporation techniques to genetically perturb the basilar papilla using CRIPSR-Cas9 deletions, followed by dissection of the basilar papilla. We also demonstrate the BP organ culture and optimal use of culture matrices, to observe the development of the epithelium and the hair cells.

In Ovo and Ex Ovo Methods to Study Avian Inner Ear Development

The chick is a cost-effective, accessible, and widely available model organism for a variety of studies. Here, a series of protocols is detailed to understand the molecular mechanisms underlying avian inner ear development and regeneration.

The inner ear perceives sound and maintains balance using the cochlea and vestibule. It does this by using a dedicated mechanosensory cell type known as ...

In Ovo Electroporation in Embryonic Chick Retina

Chicken embryonic retina is an excellent tool to study retinal development in higher vertebrates. Because of large size and external development, it is comparatively very easy to manipulate the chick embryonic retina using recombinant DNA/RNA technology. Electroporation of DNA/RNA constructs into the embryonic retina have a great advantage to study gene regulation in retinal stem/progenitor cells during retinal development. Different type of assays such as reporter gene assay, gene over-expression, gene knock down (shRNA) etc. can be performed using the electroporation technique. This video demonstrates targeted retinal injection and in ovo electroporation into the embryonic chick retina at the Hamburger and Hamilton stage 22-23, which is about embryonic day 4 (E4). Here we show a rapid and convenient in ovo electroporation technique whereby a plasmid DNA that expresses green fluorescent protein (GFP) as a marker is directly delivered into the chick embryonic subretinal space and followed by electric pulses to facilitate DNA uptake by retinal stem/progenitor cells. The new method of retinal injection and electroporation at E4 allows the visualization of all retinal cell types, including the late-born neurons1, which has been difficult with the conventional method of injection and electroporation at E1.52.

In Ovo Electroporation in Embryonic Chick Retina

The overall goal of this video is to show how to perform targeted retinal injection and in ovo electroporation of DNA/RNA constructs into the chick embryonic retina at the Hamburger and Hamilton stage 22-23, which is about embryonic day 4 (E4). This technique is very useful to study gene expression, gene regulation, and morphological change in developing chick retina.

Chicken embryonic retina is an excellent tool to study retinal development in higher vertebrates. Because of large size and external development, it is ...

Gene Transfer into Older Chicken Embryos by ex ovo Electroporation

The chicken embryo provides an excellent model system for studying gene function and regulation during embryonic development. In ovo electroporation is a powerful method to over-express exogenous genes or down-regulate endogenous genes in vivo in chicken embryos1. Different structures such as DNA plasmids encoding genes2-4, small interfering RNA (siRNA) plasmids5, small synthetic RNA oligos6, and morpholino antisense oligonucleotides7 can be easily transfected into chicken embryos by electroporation. However, the application of in ovo electroporation is limited to embryos at early incubation stages (younger than stage HH20 - according to Hamburg and Hamilton)8 and there are some disadvantages for its application in embryos at later stages (older than stage HH22 - approximately 3.5 days of development). For example, the vitelline membrane at later stages is usually stuck to the shall membrane and opening a window in the shell causes rupture of the vessels, resulting in death of the embryos; older embryos are covered by vitelline and allantoic vessels, where it is difficult to access and manipulate the embryos; older embryos move vigorously and is difficult to control the orientation through a relatively small window in the shell.
In this protocol we demonstrate an ex ovo electroporation method for gene transfer into chicken embryos at late stages (older than stage HH22). For ex ovo electroporation, embryos are cultured in Petri dishes9 and the vitelline and allantoic vessels are widely spread. Under these conditions, the older chicken embryos are easily accessed and manipulated. Therefore, this method overcomes the disadvantages of in ovo electroporation applied to the older chicken embryos. Using this method, plasmids can be easily transfected into different parts of the older chicken embryos10-12.

Gene Transfer into Older Chicken Embryos by ex ovo Electroporation

A method of gene transfer into chicken embryos at later incubation stages (older than Hamburger and Hamilton stage (HH) 22) is described. This method overcomes disadvantages of in ovo electroporation applied to older chicken embryos and is a useful technique to study gene function and regulation at older developmental stages.

The chicken embryo provides an  excellent model system for studying gene function and regulation during  embryonic development. In ovo electroporation is ...

Loss-of-Function Approach in the Embryonic Chick Retina by Using Tol2 Transposon-Mediated Transgenic Expression of Artificial microRNAs

The chick retina has long been an important model system in developmental neurobiology, with advantages including its large size, rapid development, and accessibility for visualization and experimental manipulations. However, its major technical limitation had been the lack of robust loss-of-function approaches for gene function analyses. This protocol describes a methodology of gene silencing in the developing chick retina that involves transgenic expression of artificial microRNAs (miRNAs) by using the Tol2 transposon system. In this approach, a Tol2 transposon plasmid that contains an expression cassette for the EmGFP (emerald green fluorescent protein) marker and artificial pre-miRNA sequences against a target gene is introduced into the embryonic chick retina with a Tol2 transposase expression construct by in ovo electroporation. In the transfected retinal cells, the transposase catalyzes the excision of the expression cassette from the transposon vector and its integration into host chromosomes, leading to the stable expression of miRNAs and the EmGFP protein. In our previous study, we have demonstrated that the expression of Nel, a glycoprotein that exerts multiple functions in neural development, can be significantly suppressed in the developing chick retina by using this technique. Our results indicate that this methodology induces a stable and robust suppression of gene expression and thus provides an efficient loss-of-function approach for studies of retinal development.

We have developed a novel loss-of-function approach that involves the introduction and genomic integration of artificial micro-RNA sequences into chick embryos by using in ovo electroporation and the Tol2 transposon system. This technique provides a robust and stable gene knockdown methodology for studies of gene function during development.

The chick retina has long been an important model system in developmental neurobiology, with advantages including its large size, rapid development, and ...

Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation

Samenvatting

Meer video's verkennen