Name: surgical size reduction of zebrafish for the study of embryonic pattern scaling
Uploaded: 2019-05-03T14:30:00
Description: Watch this Scientific Journal Video about Surgical Size Reduction of Zebrafish for the Study of Embryonic Pattern Scaling at JoVE.com

The work was supported by the PRESTO program of the Japan Science and Technology Agency&#160;(JPMJPR11AA)&#160; and a National Institutes of Health grant (R01GM107733).

All fish-related procedures were carried out with the approval of the Institutional Animal Care and Use Committee (IACUC) at Harvard Medical School.
1. Tool and Reagent Preparation
<ol>
	<li>Make a wire loop to chop embryos
	<ol>
		<li>Take 20 cm of stainless steel wire that is stiff and non-corrosive with a diameter of 40 &#956;m. Loop the wire through into glass capillary (1.0 mm outer diameter, 0.5 mm inner diameter, no filament), making a small loop at t...

<ol>
	<li>Cooke, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scale+of+body+pattern+adjusts+to+available+cell+number+in+amphibian+embryos.">Scale of body pattern adjusts to available cell number in amphibian embryos.</a> Nature. 290, 775-778 (1981).</li><li>Driesch, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Entwicklungsmechanische+Studien:+I.+Der+Werthe+der+beiden+ersten+Furchungszellen+in+der+Echinogdermenentwicklung.+Experimentelle+Erzeugung+von+Theil-+und+Doppelbildungen.">Entwicklungsmechanische Studien: I. Der Werthe der beiden ersten Furchungszellen in der Echinogdermenentwicklung. Experimentelle Erzeugung von Theil- und Doppelbildungen.</a> Zeitschrift fur wissenschaftliche Zoologie. , (1892).</li><li>Morgan, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Half+embryos+and+whole+embryos+from+one+of+the+first+two+blastomeres.">Half embryos and whole embryos from one of the first two blastomeres.</a> Anatomischer Anzeiger. 10, 623-638 (1895).</li><li>Ishimatsu, K., 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=Size-reduced+embryos+reveal+a+gradient+scaling-based+mechanism+for+zebrafish+somite+formation.">Size-reduced embryos reveal a gradient scaling-based mechanism for zebrafish somite formation.</a> Development. 145, (2018).</li><li>Megason, S. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+toto+imaging+of+embryogenesis+with+confocal+time-lapse+microscopy.">In toto imaging of embryogenesis with confocal time-lapse microscopy.</a> Methods in Molecular Biology. 546, 317-332 (2009).</li><li>Graeden, E., Sive, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Live+imaging+of+the+zebrafish+embryonic+brain+by+confocal+microscopy.">Live imaging of the zebrafish embryonic brain by confocal microscopy.</a> Journal of Visualized Experiments. (26), e1217 (2009).</li><li>Rosen, J. N., Sweeney, M. F., Mably, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microinjection+of+zebrafish+embryos+to+analyze+gene+function.">Microinjection of zebrafish embryos to analyze gene function.</a> Journal of Visualized Experiments. (25), e1115 (2009).</li><li>Yuan, S., Sun, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microinjection+of+mRNA+and+morpholino+antisense+oligonucleotides+in+zebrafish+embryos.">Microinjection of mRNA and morpholino antisense oligonucleotides in zebrafish embryos.</a> Journal of Visualized Experiments. (27), e1113 (2009).</li><li>Sorlien, E. L., Witucki, M. A., Ogas, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+Production+and+Identification+of+CRISPR/Cas9-generated+Gene+Knockouts+in+the+Model+System+Danio+rerio.">Efficient Production and Identification of CRISPR/Cas9-generated Gene Knockouts in the Model System Danio rerio.</a> Journal of Visualized Experiments. (138), e56969 (2018).</li><li>Kemp, H. A., Carmany-Rampey, A., Moens, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generating+chimeric+zebrafish+embryos+by+transplantation.">Generating chimeric zebrafish embryos by transplantation.</a> Journal of Visualized Experiments. (29), e1394 (2009).</li><li>Mizuno, T., Shinya, M., Takeda, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+and+tissue+transplantation+in+zebrafish+embryos.">Cell and tissue transplantation in zebrafish embryos.</a> Methods in Molecular Biology. 127, 15-28 (1999).</li><li>Cooke, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+somite+number+during+morphogenesis+of+a+vertebrate,+Xenopus+laevis.">Control of somite number during morphogenesis of a vertebrate, Xenopus laevis.</a> Nature. 254, 196-199 (1975).</li><li>Inomata, H., Shibata, T., Haraguchi, T., Sasai, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scaling+of+dorsal-ventral+patterning+by+embryo+size-dependent+degradation+of+Spemann's+organizer+signals.">Scaling of dorsal-ventral patterning by embryo size-dependent degradation of Spemann's organizer signals.</a> Cell. 153, 1296-1311 (2013).</li><li>Gomez, 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=Control+of+segment+number+in+vertebrate+embryos.">Control of segment number in vertebrate embryos.</a> Nature. 454, 335-339 (2008).</li><li>Lauschke, V. M., Tsiairis, C. D., Francois, P., Aulehla, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scaling+of+embryonic+patterning+based+on+phase-gradient+encoding.">Scaling of embryonic patterning based on phase-gradient encoding.</a> Nature. 493, 101-105 (2013).</li><li>Schindelin, 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=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nature Methods. 9, 676-682 (2012).</li><li>Almuedo-Castillo, 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=Scale-invariant+patterning+by+size-dependent+inhibition+of+Nodal+signalling.">Scale-invariant patterning by size-dependent inhibition of Nodal signalling.</a> Nature Cell Biology. 20, 1032-1042 (2018).</li><li>Koos, D. S., Ho, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+nieuwkoid+gene+characterizes+and+mediates+a+Nieuwkoop-center-like+activity+in+the+zebrafish.">The nieuwkoid gene characterizes and mediates a Nieuwkoop-center-like activity in the zebrafish.</a> Current Biology. 8, 1199-1206 (1998).</li><li>Yamanaka, 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=A+novel+homeobox+gene,+dharma,+can+induce+the+organizer+in+a+non-cell-autonomous+manner.">A novel homeobox gene, dharma, can induce the organizer in a non-cell-autonomous manner.</a> Genes and Development. 12, 2345-2353 (1998).</li><li>Jesuthasan, S., Stahle, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+microtubules+and+specification+of+the+zebrafish+embryonic+axis.">Dynamic microtubules and specification of the zebrafish embryonic axis.</a> Current Biology. 7, 31-42 (1997).</li><li>Schier, A. F., Talbot, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+zebrafish+organizer.">The zebrafish organizer.</a> Current Opinion in Genetics and Development. 8, 464-471 (1998).</li></ol>

Historically, among vertebrate animals, size reduction has been mainly performed using amphibian embryos, by bisecting the embryos along animal-vegetal axis at a blastula stage12. However, there are mainly two differences between frog and zebrafish embryos when we bisect embryos. First, at the stage when zebrafish embryos become tolerant of bisecting (blastula stage), the organizer is located in a restricted area of blastula margin18,...

Scientists have long known that embryos have a remarkable ability to form constant body proportions although embryo size can vary greatly both under natural and experimental conditions1,2,3. Despite decades of theoretical and experimental studies, this robustness to size variation, termed scaling, and its underlying mechanisms remain unknown in many tissues and organs. In order to directly capture the dynamics of the developing system, we established a reproducible and simple size reduction technique in zebrafish4, which has the great advantage in in vivo live imaging5.
Zebrafish has served as a model vertebrate animal to study multiple disciplines of biology, including developmental biology. In particular, zebrafish is ideal for in vivo live imaging6 because 1) development can proceed normally outside the mother and the egg shell, and 2) the embryos are transparent. In addition, the embryos can withstand some temperature and environmental fluctuations, which allows them to be studied in laboratory conditions. Also, in addition to conventional gene expression perturbation by morpholino and mRNA injection7,8, recent advances in CRISPR/Cas9 technology has made reverse genetics in zebrafish highly efficient9. Furthermore, many classical techniques in embryology, such as cell transplantation or tissue surgery can be applied4,10,11.
Size reduction techniques were originally developed in amphibian and other non-vertebrate animals12. For example, in Xenopus laevis, another popular vertebrate animal model, bisection along the animal-vegetal axis at blastula stage can produce size-reduced embryos12,13. However, in our hands this one-step approach results in dorsalized or ventralized embryos in zebrafish, presumably because dorsal determinants are distributed unevenly and one cannot know their localization from the morphology of embryos. Here we demonstrate an alternative two-step chopping technique for zebrafish that produces normally developing but smaller embryos. With this technique, cells are first removed from the animal pole, a region of na&#239;ve cells lacking in organizer activity. To balance the amount of yolk and cells, which is important for epiboly and subsequent morphogenesis, yolk is then removed. Here, we detail this protocol and provide two examples of size invariance in pattern formation; somite formation and ventral neural tube patterning. Combined with quantitative imaging, we utilized the size reduction technique to examine the how the sizes of somites and neural tube are affected in size reduced embryos.

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			<td height="21" style="height:21px;width:216px;">60 mm PYREX Petri dish</td>
			<td style="width:107px;">CORNING</td>
			<td style="width:119px;">&#160;3160-60</td>
			<td style="width:167px;"></td>
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			<td height="21" style="height:21px;width:216px;">Agarose</td>
			<td style="width:107px;">affymetrix</td>
			<td align="right" style="width:119px;">75817</td>
			<td>For making a mount for live imaging</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Agarose, low gelling temperature Type VII-A</td>
			<td style="width:107px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">A0701-25G</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">CaCl2</td>
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			<td>For 1/3 Ringer&#39;s solution</td>
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			<td height="21" style="height:21px;width:216px;">CaSO4</td>
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			<td>For egg water</td>
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			<td height="42" style="height:42px;width:216px;">Cover slip (25 mm x 25 mm, Thickness 1)</td>
			<td style="width:107px;">CORNING</td>
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			<td>For microscope incubator</td>
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			<td height="21" style="height:21px;width:216px;">Glass pipette</td>
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			<td>For microscope incubator</td>
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			<td height="21" style="height:21px;width:216px;">Instant sea salt</td>
			<td style="width:107px;">Instant Ocean</td>
			<td align="right" style="width:119px;">138510</td>
			<td>For egg water</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:216px;">KCl</td>
			<td style="width:107px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">P4504</td>
			<td>For 1/3 Ringer&#39;s solution</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Methyl cellulose</td>
			<td style="width:107px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">M0387-100G</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">NaCl</td>
			<td style="width:107px;">SIGMA-ALDRICH</td>
			<td style="width:119px;">S7653</td>
			<td>For 1/3 Ringer&#39;s solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Petri dish</td>
			<td style="width:107px;">Falcon</td>
			<td align="right" style="width:119px;">351029</td>
			<td>For making a mount for live imaging</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Phenol red</td>
			<td style="width:107px;">SIGMA Life Science</td>
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			<td height="42" style="height:42px;width:216px;">Pipette pump</td>
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			<td height="42" style="height:42px;width:216px;">Tricaine-S (MS222)</td>
			<td style="width:107px;">WESTERN CHEMICAL INC</td>
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			<td height="21" style="height:21px;">Ultra thin bright annealed 316L dia. 0.035 mm Stainless Steel Weaving Wires</td>
			<td style="width:107px;">Sandra</td>
			<td style="width:119px;"></td>
			<td>The wire we used was obtained ~20 years ago and we could not find exactly the same one. This product has the same material and diameter as the one we use.</td>
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surgical size reduction of zebrafish for the study of embryonic pattern scaling

In the developmental process, embryos exhibit a remarkable ability to match their body pattern to their body size; their body proportion is maintained even in embryos that are larger or smaller, within certain limits. Although this phenomenon of scaling has attracted attention for over a century, understanding the underlying mechanisms has been limited, owing in part to a lack of quantitative description of developmental dynamics in embryos of varied sizes. To overcome this limitation, we developed a new technique to surgically reduce the size of zebrafish embryos, which have great advantages for in vivo live imaging. We demonstrate that after balanced removal of cells and yolk at the blastula stage in separate steps, embryos can quickly recover under the right conditions and develop into smaller but otherwise normal embryos. Since this technique does not require special equipment, it is easily adaptable, and can be used to study a wide range of scaling problems, including robustness of morphogen mediated patterning.&#160;

Yolk volume reduction is important for normal morphology 
As recently described in Almuedo-Castillo et al.17, size reduction of embryos can be achieved without reducing yolk volume. To compare with and without yolk volume reduction, we performed both two-step chopping (both blastula and yolk) and blastula-only chopping (Figure 2 and Supplemental Movie 1). Two-step chopped embryos showed seemingly normal overall morphology compare...

Watch this Scientific Journal Video about Surgical Size Reduction of Zebrafish for the Study of Embryonic Pattern Scaling at JoVE.com

Surgical Size Reduction of Zebrafish for the Study of Embryonic Pattern Scaling

Here, we describe a method for reducing the size of zebrafish embryos without disrupting normal developmental processes. This technique enables the study of pattern scaling and developmental robustness against size change.

In the developmental process, embryos exhibit a remarkable ability to match their body pattern to their body size; their body proportion is maintained ...

Although scaling is one of the universal and fundamental attributes of developmental systems, the underlying mechanisms have not been understood in many organs and tissues. The size reduction technique of zebrafish presented in this video will advance your understanding of mechanisms underlying dynamic scaling processes. Advantages of working with zebrafish are that it is easy to perform live imaging, genetics, and quantitative analysis.Our technique is also very simple and easy to apply without any specialized equipment or intensive training. The health of embryos is the key for success with this technique. Use young fish as parents and be careful to minimize the damage by removing the chorions.And also play around in the size of the wound on the yolk, and how many cells are removed. As the embryos we use are very young and fragile, they need to be handled very carefully when transferring and chopping. At the same time, it needs to be fast so the procedure can be done in the right time window of development.Visual demonstration can give a good sense of how to produce smaller embryos effectively. To make a wire loop for embryo chopping, feed 20 centimeter long stiff and non-corrosive stainless steel wire through a glass capillary, making a small, one millimeter long loop at the top. Place a little droplet of clear nail polish onto the tip of the class capillary, between the capillary and the wire loop to hold it in place, making sure not to get any nail polish onto the loop portion, as it may damage the embryos.And then let it dry. Use lab tape to attach the glass capillary with the loop onto a wooden chopstick, leaving about two and a half centimeters of the glass capillary extending beyond the chopstick so that the chopstick part of the tool does not dip into the water later. In a 100 millimeter glass Petri dish with a plastic spatula, spread approximately 0.5 milliliters of 2%methyl cellulose near the center of the bottom thinly and evenly to a thickness of approximately 0.5 millimeters.Pour approximately 30 milliliters of one-third Ringer's solution to the side of the dish, and allow it to spread onto the rest of the dish and cover the methyl cellulose. Place previously de-chorionated embryos at the 256 cell to one K cell stage on 2%methyl cellulose, making sure the embryos are oriented onto their side. To chop blastula, use the wire loop to cut near the animal pole, perpendicular to the animal vegetal axis and chop off approximately 30 to 40%of blastoderm cells.Then gently tap the ends together to help the remaining cells stick back. For yolk, use the mounted wire to make a small wound near the vegetal pole by nicking the egg membrane, which will cause the yolk to ooze out for a few minutes, and then heal. When the yolk stops oozing out, use a pipette to move the embryo outside of the methyl cellulose in the same dish for recovery.Repeat blastula and yolk chopping for all embryos, and then leave the dish undisturbed for 30 minutes while the embryos recover. Then, use a glass pipette to transfer the embryos to the previously prepared 35 millimeter glass dish containing fresh one-third Ringer's solution and place them in a 28.5 degree Celsius incubator to allow for complete recovery before continuing with imaging. After performing two step chopping with blastula and yolk, embryos showed seemingly normal overall morphology throughout the developmental stages compared to the control embryos, other than size difference.On the other hand, blastula-only chopped embryos showed a peculiar morphology, especially at earlier stages. During epiboly, the embryos had a constricted and indented appearance. At the following somite stage, midline structures were found to be flattened at many axial levels.At later stages, the body structures adjacent to the yolk, such as the mid and hindbrain still showed a relatively flattened shape, possibly due to increased tension from the relatively larger yolk. Time lapse imaging of somite formation showed that in both control and chopped embryos, the sizes of somites that were formed at later stages were smaller compared to the ones from earlier stages. Also, throughout the somite formation stages, chopped embryos had smaller somites than the ones in control embryos.When the two step chopping technique was performed on membrane mCherry injected embryos, imaging of their spinal cords at 20 hours post fertilization showed reduction in neural tube heights due to size reduction. Two step chopping is very important to obtain smaller but otherwise normal embryos with high efficiency. It is important to remember not to chop the yolk while chopping off cells from the blastula.For yolk, make a tiny wounding on it for the content to ooze out. And the yolk membrane will heal up naturally in the proper buffer. Because the chopped embryos can be recovered quickly, any methods or analysis can be applied to normal embryos can be performed following the size reduction method.The simplicity and versatility of this technique is very powerful as anyone could introduce this technique to study scaling problem in any tissue or organ in zebrafish. We believe with this technique researchers can tackle scaling problems in a variety of systems that have been untouched before. We have already made important discoveries in scaling of somite and neural tube patterning.

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