Name: wholemount in situ hybridization for astyanax embryos
Uploaded: 2019-03-02T15:00:00
Description: Watch this Scientific Journal Video about Wholemount In Situ Hybridization for Astyanax Embryos at JoVE.com

The authors wish to thank members of the Gross lab for helpful comments on this manuscript. We wish to acknowledge four high school students who utilized this protocol during summer internships in 2017 and 2018, including Christine Cao, Michael Warden, Aki Li, and David Nwankwo. HL was supported by a UC Biology STEM Fellowship during the summer of 2017. This work was supported by grants from the National Science Foundation (DEB-1457630 to JBG), and the National Institutes of Dental and Craniofacial Research (NIH; DE025033 to JBG).

All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of the University of Cincinnati (Protocol #10-01-21-01).
1. Fixation
<ol>
	<li>Isolate desired number of Astyanax mexicanus embryos from a breeding tank and fix ~50 embryos at a time. If embryos are large and old, it may be necessary to fix 25 at a time to ensure even fixation.</li>
	<li>Depending on the age of the embryo, utilize the IACUC-approved method of anesthesia. For olde...

<ol>
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B., Hanken, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+cranial+patterning+in+the+direct&#8208;developing+frog+Eleutherodactylus+coqui+revealed+through+gene+expression.">Early cranial patterning in the direct&#8208;developing frog Eleutherodactylus coqui revealed through gene expression.</a> Evolution &amp; Development. 12 (4), 373-382 (2010).</li><li>Thisse, C., Thisse, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-resolution+in+situ+hybridization+to+whole-mount+zebrafish+embryos.">High-resolution in situ hybridization to whole-mount zebrafish embryos.</a> Nature Protocols. 3 (1), 59-69 (2008).</li><li>Cheung, M., Briscoe, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+crest+development+is+regulated+by+the+transcription+factor+Sox9.">Neural crest development is regulated by the transcription factor Sox9.</a> Development. 130 (23), 5681-5693 (2003).</li><li>Knight, R. D., Nair, S., Nelson, S. S., Afshar, A., Javidan, Y., Geisler, R., Rauch, G. J., Schilling, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=lockjaw+encodes+a+zebrafish+tfap2a+required+for+early+neural+crest+development.">lockjaw encodes a zebrafish tfap2a required for early neural crest development.</a> Development. 130 (23), 5755-5768 (2003).</li><li>Yang, J. W., Jeong, B. C., Park, J., Koh, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PHF20+positively+regulates+osteoblast+differentiation+via+increasing+the+expression+and+activation+of+Runx2+with+enrichment+of+H3K4me3.">PHF20 positively regulates osteoblast differentiation via increasing the expression and activation of Runx2 with enrichment of H3K4me3.</a> Scientific Reports. 7 (1), 8060 (2017).</li><li>Ganju, R. K., Brubaker, S. A., Meyer, J., Dutt, P., Yang, Y., Qin, S., Newman, W., Groopman, 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=The+&#945;-chemokine,+stromal+cell-derived+factor-1&#945;,+binds+to+the+transmembrane+G-protein-coupled+CXCR-4+receptor+and+activates+multiple+signal+transduction+pathways.">The &#945;-chemokine, stromal cell-derived factor-1&#945;, binds to the transmembrane G-protein-coupled CXCR-4 receptor and activates multiple signal transduction pathways.</a> Journal of Biological Chemistry. 273 (36), 23169-23175 (1998).</li><li>Cai, Y., Xin, X., Yamada, T., Muramatsu, Y., Szpirer, C., Matsumoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assignments+of+the+genes+for+rat+pituitary+adenylate+cyclase+activating+polypeptide+(Adcyap1)+and+its+receptor+subtypes+(Adcyap1r1,+Adcyap1r2,+and+Adcyap1r3).">Assignments of the genes for rat pituitary adenylate cyclase activating polypeptide (Adcyap1) and its receptor subtypes (Adcyap1r1, Adcyap1r2, and Adcyap1r3).</a> Cytogenetic and Genome Research. 71 (2), 193-196 (1995).</li><li>Stolt, C. C., Rehberg, S., Ader, M., Lommes, P., Riethmacher, D., Schachner, M., Bartsch, U., Wegner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Terminal+differentiation+of+myelin-forming+oligodendrocytes+depends+on+the+transcription+factor+Sox10.">Terminal differentiation of myelin-forming oligodendrocytes depends on the transcription factor Sox10.</a> Genes &amp; Development. 16 (2), 165-170 (2002).</li><li>Kimura, T., Takehana, Y., Naruse, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=pnp4a+is+the+causal+gene+of+the+Medaka+Iridophore+mutant+guanineless.">pnp4a is the causal gene of the Medaka Iridophore mutant guanineless.</a> G3: Genes, Genomes, Genetics. 7 (4), 1357-1363 (2017).</li><li>Monsoro-Burq, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+protocol+for+whole-mount+in+situ+hybridization+on+Xenopus+embryos.">A rapid protocol for whole-mount in situ hybridization on Xenopus embryos.</a> Cold Spring Harbor Protocols. (8), pp.pdb-prot4809 (2007).</li><li>Schulz, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+hybridization+to+Drosophila+testes.">In situ hybridization to Drosophila testes.</a> Cold Spring Harbor Protocols. (8), pp.pdb-prot4764 (2007).</li></ol>

Owing to the vulnerability of RNA to degradation, one of the most critical steps in the protocol concerns the sterile synthesis of the RNA probe. However, if a probe is carefully generated, and provides good results, it can be reused in subsequent staining reactions. A second crucial step is the careful production of all reagents used throughout the protocol. Since this protocol involves several days and many small steps, it is essential that all reagents are accurately produced, and stored in a sterile manner. Further, ...

In situ hybridization is a common method for staining fixed tissues to visualize gene expression patterns1. This technique has been performed for years in other traditional2 and non-traditional3 model systems, for a variety of biological studies. However, several steps and reagents are necessary to successfully perform this procedure. For investigators who have never performed this technique, initiating the process can be intimidating owing to the many steps involved. Further, the lengthy nature of this procedure lends itself to technical errors, which can be challenging to troubleshoot. 
The overall goal of this article is to present a simple and straightforward method that will render this hybridization technique accessible to a wide audience. To reduce the introduction of errors, we present a straightforward approach that yields high quality gene expression staining and minimizes non-specific background signal. This procedure is similar to other approaches developed in traditional model systems, such as Danio rerio4. Here, we aim to facilitate careful implementation of each step using a downloadable checklist (Supplemental File 1), to promote careful implementation of the protocol. The rationale for doing this is to facilitate organization through the many steps involved in this procedure. This article is appropriate for researchers interested in performing whole-mount in situ hybridization in developing embryos, but have not yet performed the procedure. The advantage of the chosen approach for Astyanax researchers is that it has been tested and proven in both cavefish and surface fish morphs, thereby facilitating comparative expression analyses. The presented method can be used by researchers in studies on Astyanax and other systems.

<table>
	<tbody>
		<tr>
			<td>10 mL Serological Pipette</td>
			<td>VWR</td>
			<td>89130-888</td>
			<td></td>
		</tr>
		<tr>
			<td>1000 mL Filtration Unit</td>
			<td>VWR</td>
			<td>89220-698</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Conical</td>
			<td>VWR-Greiner</td>
			<td>82050-278</td>
			<td></td>
		</tr>
		<tr>
			<td>25 mL Serological Pipette</td>
			<td>VWR</td>
			<td>89130-890</td>
			<td></td>
		</tr>
		<tr>
			<td>250 mL Filtration Unit</td>
			<td>VWR</td>
			<td>89220-694</td>
			<td></td>
		</tr>
		<tr>
			<td>5 mL Serological Pipette</td>
			<td>VWR</td>
			<td>89130-886</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Conical</td>
			<td>VWR-Falcon</td>
			<td>21008-940</td>
			<td></td>
		</tr>
		<tr>
			<td>500 mL Filtration Unit</td>
			<td>VWR</td>
			<td>89220-696</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Digoxigenin-AP, Fab fragments</td>
			<td>Sigma-Roche</td>
			<td>11093274910</td>
			<td></td>
		</tr>
		<tr>
			<td>BCIP</td>
			<td>Sigma-Aldrich</td>
			<td>B8503-1G</td>
			<td>1 g</td>
		</tr>
		<tr>
			<td>Blocking Solution</td>
			<td>Sigma-Roche</td>
			<td>11 096 176 001</td>
			<td>50 g</td>
		</tr>
		<tr>
			<td>Citric Acid</td>
			<td>Fisher Scientific</td>
			<td>A104-500</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>DIG RNA Labeling Kit (SP6/T7)</td>
			<td>Sigma-Roche</td>
			<td>11175025910</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf Tubes</td>
			<td>VWR</td>
			<td>20170-577</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Fisher-Decon</td>
			<td>04-355-223</td>
			<td>1 Gal</td>
		</tr>
		<tr>
			<td>Formamide</td>
			<td>Thermo Fisher Scientific</td>
			<td>17899</td>
			<td>100 mL</td>
		</tr>
		<tr>
			<td>Glass dram vials</td>
			<td>VWR</td>
			<td>66011-041</td>
			<td>1 Dr</td>
		</tr>
		<tr>
			<td>Glass Pipettes</td>
			<td>Fisher Scientific</td>
			<td>13-678-8A</td>
			<td></td>
		</tr>
		<tr>
			<td>HCl</td>
			<td>Thermal-ScientificPharmco-AAPER</td>
			<td>284000ACS</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>Sigma</td>
			<td>H3393-25KU</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium Chloride-crystalline</td>
			<td>Fisher Scientific</td>
			<td>M33-500</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>Maleic Acid</td>
			<td>Sigma</td>
			<td>M0375-100g</td>
			<td>100g</td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher Scientific</td>
			<td>A452-4</td>
			<td>4L</td>
		</tr>
		<tr>
			<td>Molecular-grade Water (RNase-free)</td>
			<td>VWR</td>
			<td>7732-18-5</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Fisher Scientific</td>
			<td>S271-3</td>
			<td>3 kg</td>
		</tr>
		<tr>
			<td>NaOH pellets</td>
			<td>Fisher Scientific</td>
			<td>S318-500</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>NBT Substrate powder</td>
			<td>ThermoFisher Scientific</td>
			<td>34035</td>
			<td>1 g</td>
		</tr>
		<tr>
			<td>Normal Goat Serum</td>
			<td>Fisher-Invitrogen</td>
			<td>31873</td>
			<td></td>
		</tr>
		<tr>
			<td>Nutating Mixer</td>
			<td>VWR</td>
			<td>82007-202</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma</td>
			<td>158127-500g</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>PBS 10x</td>
			<td>Fisher Scientific</td>
			<td>BP399-20</td>
			<td>20L</td>
		</tr>
		<tr>
			<td>Proteinase K (200mg/10ml)</td>
			<td>Qiagen</td>
			<td>19133</td>
			<td>10 mL</td>
		</tr>
		<tr>
			<td>Plastic Pipettes</td>
			<td>VWR-Samco</td>
			<td>14670-147</td>
			<td></td>
		</tr>
		<tr>
			<td>RNAse</td>
			<td>Sigma</td>
			<td>R2020-250mL</td>
			<td>250 mL</td>
		</tr>
		<tr>
			<td>Shaking Water Bath 12 L</td>
			<td>VWR</td>
			<td>10128-126</td>
			<td>12 L</td>
		</tr>
		<tr>
			<td>Standard Analog Shaker</td>
			<td>VWR</td>
			<td>89032-092</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris</td>
			<td>Sigma Millipore-OmniPur</td>
			<td>9210-500GM</td>
			<td>500 g</td>
		</tr>
		<tr>
			<td>tRNA Yeast</td>
			<td>Fisher-Invitrogen</td>
			<td>15401011</td>
			<td>25 mg</td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma</td>
			<td>P9416-50mL</td>
			<td>50 mL</td>
		</tr>
		<tr>
			<td>Vortex-Genie 2</td>
			<td>Fisher Scientific-Scientific Industries, Inc</td>
			<td>50-728-002</td>
			<td></td>
		</tr>
		<tr>
			<td>Lithium Chloride (LiCl)</td>
			<td>Sigma-Aldrich</td>
			<td>203637-10G</td>
			<td>10 g</td>
		</tr>
	</tbody>
</table>

wholemount in situ hybridization for astyanax embryos

In recent years, a draft genome for the blind Mexican cavefish (Astyanax mexicanus) has been released, revealing the sequence identities for thousands of genes. Prior research into this emerging model system capitalized on comprehensive genome-wide investigations that have identified numerous quantitative trait loci (QTL) associated with various cave-associated phenotypes. However, the ability to connect genes of interest to the heritable basis for phenotypic change remains a significant challenge. One technique that can facilitate deeper understanding of the role of development in troglomorphic evolution is whole-mount in situ hybridization. This technique can be implemented to directly compare gene expression between cave- and surface-dwelling forms, nominate candidate genes underlying established QTL, identify genes of interest from next-generation sequencing studies, or develop other discovery-based approaches. In this report, we present a simple protocol, supported by a flexible checklist, that can be widely adapted for use well beyond the presented study system. It is hoped that this protocol can serve as a broad resource for the Astyanax community and beyond.

In this report, we provide a simple and straightforward approach to perform labeling of embryonic Astyanax specimens for high-quality gene expression analysis. This technique can be carried out in either four or five days, and each principal step in the procedure is represented in a color-coded flowchart (Figure 1). Once completed, stained embryos should harbor a dark purple chromatic label in tissues expressing the particular gene of interest. We ha...

Watch this Scientific Journal Video about Wholemount In Situ Hybridization for Astyanax Embryos at JoVE.com

Wholemount In Situ Hybridization for Astyanax Embryos

This protocol enables visualization of gene expression in embryonic Astyanax cavefish. This approach has been developed with the goal of maximizing gene expression signal, while minimizing non-specific background staining.

Wholemount In Situ Hybridization for Astyanax Embryos

In recent years, a draft genome for the blind Mexican cavefish (Astyanax mexicanus) has been released, revealing the sequence identities for thousands of ...

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