Name: genotyping of sea anemone during early development
Uploaded: 2019-05-13T14:30:00
Description: Watch this Scientific Journal Video about Genotyping of Sea Anemone during Early Development at JoVE.com

We thank anonymous reviewers for comments on the earlier version of the manuscript, which improved the manuscript. This work was supported by funds from the University of Arkansas.

1. Induction of spawning, in vitro fertilization, and de-jellying
<ol>
	<li>Maintain Nematostella vectensis in seawater with a salinity of 12 parts per thousand (ppt) in darkness at 16 &#176;C, feeding Artemia daily.</li>
	<li>On the day before spawning induction, place animals in a temperature- and light-controlled incubator. Program the incubator so that the animals are exposed to 8 h of light at 25 &#176;C. Optional: Feed a small piece (&#60;1 mm3) of oyster to individual animal...

<ol>
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Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR+knockouts+reveal+an+endogenous+role+for+ancient+neuropeptides+in+regulating+developmental+timing+in+a+sea+anemone.">CRISPR knockouts reveal an endogenous role for ancient neuropeptides in regulating developmental timing in a sea anemone.</a> eLife. 7, e39742 (2018).</li><li>He, S. N., 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=An+axial+Hox+code+controls+tissue+segmentation+and+body+patterning+in+Nematostella+vectensis.">An axial Hox code controls tissue segmentation and body patterning in Nematostella vectensis.</a> Science. 361 (6409), 1377 (2018).</li><li>Ikmi, A., McKinney, S. A., Delventhal, K. M., Gibson, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TALEN+and+CRISPR/Cas9-mediated+genome+editing+in+the+early-branching+metazoan+Nematostella+vectensis.">TALEN and CRISPR/Cas9-mediated genome editing in the early-branching metazoan Nematostella vectensis.</a> Nature Communications. 5, 5486 (2014).</li><li>Servetnick, M. D., 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=Cas9-mediated+excision+of+Nematostella+brachyury+disrupts+endoderm+development,+pharynx+formation+and+oral-aboral+patterning.">Cas9-mediated excision of Nematostella brachyury disrupts endoderm development, pharynx formation and oral-aboral patterning.</a> Development. 144 (16), 2951-2960 (2017).</li><li>Kraus, Y., Aman, A., Technau, U., Genikhovich, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pre-bilaterian+origin+of+the+blastoporal+axial+organizer.">Pre-bilaterian origin of the blastoporal axial organizer.</a> Nature Communications. 7, 11694 (2016).</li><li>Fritzenwanker, J. H., Genikhovich, G., Kraus, Y., Technau, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+development+and+axis+specification+in+the+sea+anemone+Nematostella+vectensis.">Early development and axis specification in the sea anemone Nematostella vectensis.</a> Developmental Biology. 310 (2), 264-279 (2007).</li><li>Lee, P. N., Kumburegama, S., Marlow, H. Q., Martindale, M. Q., Wikramanayake, 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=Asymmetric+developmental+potential+along+the+animal-vegetal+axis+in+the+anthozoan+cnidarian,+Nematostella+vectensis,+is+mediated+by+Dishevelled.">Asymmetric developmental potential along the animal-vegetal axis in the anthozoan cnidarian, Nematostella vectensis, is mediated by Dishevelled.</a> Developmental Biology. 310 (1), 169-186 (2007).</li><li>Shinzato, 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=Using+the+Acropora+digitifera+genome+to+understand+coral+responses+to+environmental+change.">Using the Acropora digitifera genome to understand coral responses to environmental change.</a> Nature (London). 476 (7360), 320-323 (2011).</li><li>Gold, D. 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V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR/Cas9-mediated+genome+editing+in+a+reef-building+coral.">CRISPR/Cas9-mediated genome editing in a reef-building coral.</a> Proceedings of the National Academy of Sciences of the United States of America. 115 (20), 5235-5240 (2018).</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=High+doses+of+CRISPR/Cas9+ribonucleoprotein+efficiently+induce+gene+knockout+with+low+mosaicism+in+the+hydrozoan+Clytia+hemisphaerica+through+microhomology-mediated+deletion.">High doses of CRISPR/Cas9 ribonucleoprotein efficiently induce gene knockout with low mosaicism in the hydrozoan Clytia hemisphaerica through microhomology-mediated deletion.</a> Scientific Reports. 8, 11734 (2018).</li><li>Artigas, G. 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=A+gonad-expressed+opsin+mediates+light-induced+spawning+in+the+jellyfish+Clytia.">A gonad-expressed opsin mediates light-induced spawning in the jellyfish Clytia.</a> eLife. 7, e29555 (2018).</li></ol>

Described here a PCR-based protocol to genotype a single sea anemone embryo without sacrificing the animal. Following spawning and de-jellying, the fertilized eggs are allowed to develop into gastrulae. The aboral region of each gastrula embryo is surgically removed, and the isolated aboral tissue is used for subsequent genomic DNA extraction, while the remaining post-surgery embryos heal and continue development. The gDNA extracts are then used for a PCR assay to determine the genotype of each embryo. This method takes ...

Cnidarians represent a diverse group of animals that include jellyfish, corals, and sea anemones. They are diploblasts, composed of ectoderm and endoderm that are separated by an extracellular matrix (mesoglea). Cnidaria is a sister group to speciose Bilateria, to which traditional animal models such as Drosophila and Mus belong1. Additionally, the Cnidaria-Bilateria divergence is thought to have occurred in the pre-Cambrian period2. As such, comparative studies of cnidarians and bilaterians are essential for gaining insights into the biology of their most recent common ancestor. Recently, comparative genomics has revealed that cnidarians and bilaterians share many developmental toolkit genes such as notch and bHLH, implying that their common ancestor already had these genes3. However, the role of these developmental toolkit genes in the last common ancestor of Cnidaria and Bilateria is comparably less well understood. To address this problem, it is critical to study how these deeply conserved genes function in cnidarians.
One of the emerging cnidarian genetic models is the anthozoan Nematostella vectensis. Its genome has been sequenced3, and a variety of genetic tools, including morpholino-mediated gene knockdown, meganuclease-mediated transgenesis, and CRISPR-Cas9-mediated gene knockins and knockouts, are now available for use in this animal. In addition, Nematostella development is relatively well understood. During embryogenesis, gastrulation occurs by invagination4, and the embryo develops into a free-swimming planula larva. The planula subsequently transforms into a sessile polyp with a mouth and circumoral tentacles. The polyp then grows and reaches sexual maturity.
CRISPR-Cas9-mediated targeted mutagenesis is now routinely used to study gene function in Nematostella vectensis5,6,7,8,9. To generate knockout mutants in Nematostella, a cocktail containing locus-specific single-guide RNAs and the endonuclease Cas9 protein is first injected into unfertilized or fertilized eggs to produce F0 founder animals that typically show mosaicism. F0 animals are subsequently raised to sexual maturity and crossed with each other to produce an F1 population, a subset of which may be knockout mutants6. Alternatively, sexually mature F0 animals can be crossed with wild-type animals to generate F1 heterozygous animals, and F1 heterozygotes that carry a knockout allele in the locus of interest can then be crossed with each other to produce F2 offspring, one-quarter of which are expected to be knockout mutants5. Both approaches require a method to identify knockout mutants from a genetically heterogeneous population. Polyp tentacles can be used to extract genomic DNA for genotyping6,7. However, in cases where the developmental function of the gene of interest is being investigated and mutant embryos do not reach the polyp stage (i.e., due to larval lethality associated with the mutation), knockout mutants need to be identified early in ontogeny. Described here is a PCR-based protocol to genotype individual animals at the gastrula stage without sacrificing the animal, which enables identification of knockout mutants from a genetically heterogeneous population of embryos. The duration of the entire genotyping process depends on the number of embryos to be screened, but it minimally requires 4-5 h.

<table>
	<tbody>
		<tr>
			<td>Drosophila Peltier Refrigerated Incubator</td>
			<td>Shellab</td>
			<td>SRI6PF</td>
			<td>Used for spawning induction</td>
		</tr>
		<tr>
			<td>Instant ocean sea salt</td>
			<td>Instant ocean</td>
			<td>138510</td>
			<td></td>
		</tr>
		<tr>
			<td>Brine shrimp cysts</td>
			<td>Aquatic Eco-Systems, Inc.</td>
			<td>BS90</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Cysteine Hydrochloride</td>
			<td>Sigma Aldrich</td>
			<td>C7352</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard Orbital Shaker, Model 3500</td>
			<td>VWR</td>
			<td>89032-092</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIS-HCl, 1M, pH8.0</td>
			<td>QUALITY BIOLOGICAL</td>
			<td>351-007-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>VWR</td>
			<td>BDH9258</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA, 0.5M pH8</td>
			<td>VWR</td>
			<td>BDH7830-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma Aldrich</td>
			<td>P9416</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonidet-P40 Substitute</td>
			<td>US Biological</td>
			<td>N3500</td>
			<td></td>
		</tr>
		<tr>
			<td>Proteinase K solution (20 mg/mL), RNA grade</td>
			<td>ThermoFisher</td>
			<td>25530049</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>VWR</td>
			<td>710</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Dissecting needle holder</td>
			<td>Roboz</td>
			<td>RS-6060</td>
			<td></td>
		</tr>
		<tr>
			<td>Tungsten dissecting needle</td>
			<td>Roboz</td>
			<td>RS-6063</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR Eppendorf Mastercycler Thermal Cyclers</td>
			<td>Eppendorf</td>
			<td>E6336000024</td>
			<td></td>
		</tr>
		<tr>
			<td>Phusion High-Fidelity DNA polymerase</td>
			<td>New England BioLabs</td>
			<td>M0530L</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTP mix</td>
			<td>New England BioLabs</td>
			<td>N0447L</td>
			<td></td>
		</tr>
		<tr>
			<td>GLWamide universal forward primer</td>
			<td></td>
			<td></td>
			<td>5&#8217;- CATGCGGAGACCAAGCGCAAGGC-3&#8217;</td>
		</tr>
		<tr>
			<td>Reverse primer specific to glw-a</td>
			<td></td>
			<td></td>
			<td>5&#8217;-CCAGATGCCTGGTGATAC-3&#8217;</td>
		</tr>
		<tr>
			<td>Reverse primer specific to glw-c </td>
			<td></td>
			<td></td>
			<td>5&#8217;- CGGCCGGCGCATATATAG-3&#8217;</td>
		</tr>
	</tbody>
</table>

genotyping of sea anemone during early development

Described here is a PCR-based protocol to genotype the gastrula stage embryo of the anthozoan cnidarian Nematostella vectensis without sacrificing the life of the animal. Following in vitro fertilization and de-jellying, zygotes are allowed to develop for 24 h at room temperature to reach the early- to mid-gastrula stage. The gastrula embryos are then placed on an agarose gel bed in a Petri dish containing seawater. Under the dissecting microscope, a tungsten needle is used to surgically separate an aboral tissue fragment from each embryo. Post-surgery embryos are then allowed to heal and continue development. Genomic DNA is extracted from the isolated tissue fragment and used as a template for locus-specific PCR. The genotype can be determined based on the size of PCR products or presence/absence of allele-specific PCR products. Post-surgery embryos are then sorted according to the genotype. The duration of the entire genotyping process depends on the number of embryos to be screened, but it minimally requires 4&#8211;5 h. This method can be used to identify knockout mutants from a genetically heterogeneous population of embryos and enables analyses of phenotypes during development.

The Nematostella genome has a single locus that encodes a precursor protein for the neuropeptide GLWamide. Three knockout mutant alleles at this locus (glw-a, glw-b, and glw-c) have been previously reported5. Four heterozygous males carrying a wild-type allele (+) and knockout allele glw-c at the GLWamide locus (genotype: +/glw-c) were crossed with a heterozygous fem...

Watch this Scientific Journal Video about Genotyping of Sea Anemone during Early Development at JoVE.com

Genotyping of Sea Anemone during Early Development

The goal of this protocol is to genotype the sea anemone Nematostella vectensis during gastrulation without sacrificing the embryo.

Described here is a PCR-based protocol to genotype the gastrula stage embryo of the anthozoan cnidarian Nematostella vectensis without sacrificing the ...

This protocol enables a researcher to identify mutant sea anemones during early embryogenesis so that post-embryonic developmental phenotype can be analyzed. The main advantage of this technique is that it can be used to genotype individual sea anemones early in ontogeny without sacrificing the life of the animal. Demonstrating this procedure will be Miguel Silva, a graduate student from my laboratory.On the day before spawning induction, place the anemone nematostella vectensis in a temperature-and light-controlled incubator, programming the incubator so that the animals are exposed to eight hours of light at 25 degrees Celsius. On the following day, remove the animals from the incubator and leave them on a bench top at room temperature with the light on to allow spawning, which will occur within the following one and a half to two hours. Use a transfer pipette who's tip is cut to enlarge the opening to place egg packages from the female container into a sperm-containing male container and leave them in the male container for at least 15 minutes to allow for fertilization.After fertilization, to dejelly the egg packages, place them in seawater containing 3%cysteine on a glass Petri dish and gently agitate on a shaker for 12 minutes. Then break up clumps with a plastic pipette and continue to agitate for another two to three minutes until completely dejellied. Keep the fertilized eggs on the same dish at 16 degrees Celsius or at room temperature.On the next day, prepare DNA extraction buffer as described in the manuscript, mix well by vortexing, and aliquot it into PCR tubes by adding 20 microliters to each tube. Dissolve 1%agarose in seawater, pour it into a Petri dish to cover the bottom, and cool on a bench top to make a gel bed. Cover the gel bed with fresh seawater.Transfer 24-hour post-fertilization embryos using a pipette into the agarose gel bed-containing Petri dish. Insert a tungsten needle into a need holder and sterilize by dipping its tip in alcohol and placing it in flame to burn off the alcohol. Under a dissecting microscope, make a depression on the agarose by using the tungsten needle to remove a piece of surface agarose about size of an embryo to be manipulated.Then, using the tungsten needle, place the embryo into the depression with its lateral side facing down in order to restrict the movement of the embryo for microsurgery. In order to perform successful surgery, it is critical to restrict the movement of the embryo. With the tungsten needle, surgically remove a piece of aboral tissue along the oral aboral axis, located opposite to the oral blastoporal opening.With a P20 pipette, transfer the isolated aboral tissue to a PCR tube containing 20 microliters of DNA extraction buffer. Transfer the post-surgery embryo into a well of a 24-well plate containing at least 500 microliters of fresh seawater. And place the plate containing post-surgery embryos in an incubator at 16 degrees Celsius until genotyping is completed.To extract genomic DNA from single embryos, first briefly spin down the PCR tubes containing the DNA extraction buffer and isolated embryonic tissues using a mini centrifuge. Then incubate the tubes at 55 degrees Celsius for three hours while vortexing for 30 second every 30 minutes to ensure breakup of cell clumps and enhance cell lysis. After inactivating proteinase K at 95 degrees Celsius for four minutes, set up a PCR reaction using extracted genomic DNA as a template to amplify the locus of interest.Design desired primers as described in the manuscript. Set up a 20 microliter PCR reaction. After completed PCR, run agarose gel electrophoresis to determine the size and presence or absence of PCR products, making sure to adjust the condition of agarose gel electrophoresis depending on the expected size of PCR products.Use PCR results regarding the size and presence or absence or PCR products to assign a genotype to each post-surgical embryo and then sort embryos according to their genotype. The nematostella genome has a single locus that encodes a precursor protein for the neuropeptide, GLWamide. Three knockout mutant alleles at the locus have been previously reported.PCR results from randomly sampled embryos among the progeny of an F1 cross between one heterozygous female carrying an A knockout allele and heterozygous males carrying a C knockout allele show different genotypes. Embryos one and two show a single PCR band corresponding the expected size of A knockout allele. Embryos three and six show two PCR bands with the expected sizes for knockout alleles A and C.Embryos four, seven, and eight show a single PCR band corresponding to the expected size of C knockout allele.Embryo 5 shows no bands, suggesting the lack of primer binding. To rule out the possibility of genomic DNA extraction failure, another PCR was run using a reverse primer that can bind to the wild type sequence. Where a PCR product of an expected size was detected, genomic DNA extraction was successful.Whereas no product suggested a failure in extraction. Although this protocol is designed for sea anemone embryos, it sure be possible to apply this method to other cnidarians, such as corals and jellyfish, where genomic information and embryos are accessible. Following this procedure, the identified mutants are used to assess developmental phenotype.For instance, histological techniques such as immunostaining can be used to assess defects in morphology, while in situ hybridization, realtime quantitative RT-PCR, and RNA-seq can be used to assess defects in gene expression. Also, live imaging can be used to assess defects in behavior during post-embryonic development, such as in larvae or in early polyps.

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Developmental Biology

Protocols for Obtaining Zygotic and Somatic Embryos for Studying the Regulation of Early Embryo Development in the Model Legume Medicago truncatula

Early embryogenesis starting from a single cell zygote goes through rapid cell division and morphogenesis, and is morphologically characterized by pre-globular, globular, heart, torpedo and cotyledon stages. This progressive development is under the tight regulation of a complex molecular network. Harvesting sufficient early embryos at a similar stage of development is essential for investigating the cellular and molecular regulation of early embryogenesis. This is not straightforward since early embryogenesis undergoes rapid morphogenesis in a short while e.g. 8 days for Medicago truncatula to reach the early cotyledon stage. Here, we address the issue by two approaches. The first one establishes a linkage between embryo development and pod morphology in helping indicate the stage of the zygotic embryo. This is particularly based on the number of pod spirals and development of the spines. An alternative way to complement the in vivo studies is via culturing leaf explants to produce somatic embryos. The medium includes an unusual hormone combination - an auxin (1-naphthaleneacetic acid), a cytokinin (6-benzylaminopurine), abscisic acid and gibberellic acid. The different stages can be discerned growing out of the callus without dissection.

Protocols for Obtaining Zygotic and Somatic Embryos for Studying the Regulation of Early Embryo Development in the Model Legume Medicago truncatula

The goal is to illustrate that the model legume Medicago truncatula can be readily utilized to investigate the regulation of early plant embryogenesis to complement the non-legume Arabidopsis model. Pod morphology is linked to zygotic embryogenesis stages and a protocol to collect embryos using tissue culture is also provided.

Early embryogenesis starting from a single cell zygote goes through rapid cell division and morphogenesis, and is morphologically characterized by ...

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo development due to their similar developmental process. Although genetic factors are known to affect early embryonic development, the discovery of such factors has been a serious challenge. Microarray technology allows quantitative measurement and gene expression profiling of transcript levels on a genome-wide basis. One of the main decisions that have to be made when planning a microarray experiment is whether to use a one- or two-color approach. Two-color design increases technical replication, minimizes variability, improves sensitivity and accuracy as well as allows having loop designs, defining the common reference samples. Although microarray is a powerful biological tool, there are potential pitfalls that can attenuate its power. Hence, in this technical paper we demonstrate an optimized protocol for RNA extraction, amplification, labeling, hybridization of the labeled amplified RNA to the array, array scanning and data analysis using the two-color analysis strategy.

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform

Microarray technology allows quantitative measurement and gene expression profiling of transcripts on a genome-wide basis. Therefore, this protocol provides an optimized technical procedure in a two-color custom made bovine array using Day 7 bovine embryos to demonstrate the feasibility of using low amount of total RNA.

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo ...

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Cnidarians, and specifically Hydra, were the first animals shown to regenerate damaged or severed structures, and indeed such studies arguably launched modern biological inquiry through the work of Trembley more than 250 years ago. Presently the study of regeneration has seen a resurgence using both &#34;classic&#34; regenerative organisms, such as the Hydra, planaria and Urodeles, as well as a widening spectrum of species spanning the range of metazoa, from sponges through mammals. Besides its intrinsic interest as a biological phenomenon, understanding how regeneration works in a variety of species will inform us about whether regenerative processes share common features and/or species or context-specific cellular and molecular mechanisms. The starlet sea anemone, Nematostella vectensis, is an emerging model organism for regeneration. Like Hydra, Nematostella is a member of the ancient phylum, cnidaria, but within the class anthozoa, a sister clade to the hydrozoa that is evolutionarily more basal. Thus aspects of regeneration in Nematostella will be interesting to compare and contrast with those of Hydra and other cnidarians. In this article, we present a method to bisect, observe and classify regeneration of the aboral end of the Nematostella adult, which is called the physa. The physa naturally undergoes fission as a means of asexual reproduction, and either natural fission or manual amputation of the physa triggers re-growth and reformation of complex morphologies. Here we have codified these simple morphological changes in a Nematostella Regeneration Staging System (the NRSS). We use the NRSS to test the effects of chloroquine, an inhibitor of lysosomal function that blocks autophagy. The results show that the regeneration of polyp structures, particularly the mesenteries, is abnormal when autophagy is inhibited.

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Here we demonstrate how to induce and monitor regeneration in the Starlet Sea Anemone Nematostella vectensis, a model cnidarian anthozoan. We demonstrate how to amputate and categorize regeneration using a morphological staging system, and we use this system to reveal a requirement for autophagy in regenerating polyp structures.

Cnidarians, and specifically Hydra, were the first animals shown to regenerate damaged or severed structures, and indeed such studies arguably launched ...

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early embryonic development, kinase activity is highly dynamic and widespread across the embryo. Pharmacological and genetic approaches are commonly used to probe kinase activities. Unfortunately, it is challenging to achieve superior spatial and temporal resolution using these strategies. Furthermore, it is not feasible to control the kinase activity in a reversible fashion in live cells and multicellular organisms. Such a limitation remains a bottleneck for achieving a quantitative understanding of kinase activity during development and differentiation. This work presents an optogenetic strategy that takes advantage of a bicistronic system containing photoactivatable proteins Arabidopsis thaliana cryptochrome 2 (CRY2) and the N-terminal domain of cryptochrome-interacting basic-helix-loop-helix (CIBN). Reversible activation of the mitogen-activated protein kinase (MAPK) signaling pathway is achieved through light-mediated protein translocation in live cells. This approach can be applied to mammalian cell cultures and live vertebrate embryos. This bicistronic system can be generalized to control the activity of other kinases with similar activation mechanisms and can be applied to other model systems.

Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development

This protocol describes an optogenetic strategy to modulate mitogen-activated protein kinase (MAPK) activity during cell differentiation and Xenopus embryonic development. This method allows for the reversible activation of the MAPK signaling pathway in mammalian cell culture and in multicellular live organisms, like Xenopus embryos, with high spatial and temporal resolution.

Kinase activity is crucial for a plethora of cellular functions, including cell proliferation, differentiation, migration, and apoptosis. During early ...

Visualization of Cellular Electrical Activity in Zebrafish Early Embryos and Tumors

Bioelectricity, endogenous electrical signaling mediated by ion channels and pumps located on the cell membrane, plays important roles in signaling processes of excitable neuronal and muscular cells and many other biological processes, such as embryonic developmental patterning. However, there is a need for in vivo electrical activity monitoring in vertebrate embryogenesis. The advances of genetically encoded fluorescent voltage indicators (GEVIs) have made it possible to provide a solution for this challenge. Here, we describe how to create a transgenic voltage indicator zebrafish using the established voltage indicator, ASAP1 (Accelerated Sensor of Action Potentials 1), as an example. The Tol2 kit and a ubiquitous zebrafish promoter, ubi, were chosen in this study. We also explain&#160;the processes of Gateway site-specific cloning, Tol2 transposon-based zebrafish transgenesis, and the imaging process for early-stage fish embryos and fish tumors using regular epifluorescent microscopes. Using this fish line, we found that there are cellular electric voltage changes during zebrafish embryogenesis, and fish larval movement. Furthermore, it was observed that in a few zebrafish malignant peripheral nerve sheath tumors, the tumor cells were generally polarized compared to the surrounding normal tissues.

Here, we show the process of creating a cellular electric voltage reporter zebrafish line to visualize embryonic development, movement, and fish tumor cells in vivo.

Bioelectricity, endogenous electrical signaling mediated by ion channels and pumps located on the cell membrane, plays important roles in signaling ...

Analysis of Cardiac Chamber Development During Mouse Embryogenesis Using Whole Mount Epifluorescence

The goal of this protocol is to describe a method for the dissection of mouse embryos and visualization of embryonic mouse ventricular chambers during heart development using ventricular specific fluorescent reporter knock-in mice (MLC-2v-tdTomato mice). Heart development involves a linear heart tube formation, the heart tube looping, and four chamber septation. These complex processes are highly conserved in all vertebrates. The mouse embryonic heart has been widely used for heart developmental studies. However, due to their extremely small size, dissecting mouse embryonic hearts is technically challenging. In addition, visualization of cardiac chamber formation often needs in situ hybridization, beta-galactosidase staining using LacZ reporter mice, or immunostaining of sectioned embryonic hearts. Here, we describe how to dissect mouse embryonic hearts and directly visualize ventricular chamber formation of MLC-2v-tdTomato mice using whole mount epifluorescent microscopy. With this method, it is possible to directly examine heart tube formation and looping, and four chamber formation without further experimental manipulation of mouse embryos. Although the MLC-2v-tdTomato reporter knock-in mouse line is used in this protocol as an example, this protocol can be applied to other heart-specific fluorescent reporter transgenic mouse lines.

We present the protocols to examine mouse heart development using whole mount epifluorescent microscopy on mouse embryos dissected from ventricular specific MLC-2v-tdTomato reporter knock-in mice. This method allows us to directly visualize each stage of the ventricular formation during mouse heart development without labor-intensive histochemical methods.

The goal of this protocol is to describe a method for the dissection of mouse embryos and visualization of embryonic mouse ventricular chambers during ...

Genotyping and Quantification of In Situ Hybridization Staining in Zebrafish

In situ hybridization (ISH) is an important technique that enables researchers to study mRNA distribution in situ and has been a critical technique in developmental biology for decades. Traditionally, most gene expression studies relied on visual evaluation of the ISH signal, a method that is prone to bias, particularly in cases where sample identities are known a priori. We have previously reported on a method to circumvent this bias and provide a more accurate quantification of ISH signals. Here, we present a simple guide to apply this method to quantify the expression levels of genes of interest in ISH-stained embryos and correlate that with their corresponding genotypes. The method is particularly useful to quantify spatially restricted gene expression signals in samples of mixed genotypes and it provides an unbiased and accurate alternative to the traditional visual scoring methods.

Gene editing technologies have enabled researchers to generate zebrafish mutants to investigate gene function with relative ease. Here, we provide a guide to perform parallel embryo genotyping and quantification of in situ hybridization signals in zebrafish. This unbiased approach provides greater accuracy in phenotypical analyses based on in situ hybridization.

In situ hybridization (ISH) is an important technique that enables researchers to study mRNA distribution in situ and has been a critical technique in ...

Preparation of Small RNA Libraries for Sequencing from Early Mouse Embryos

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs during early development are technically challenging due to the limiting cell number. Moreover, many approaches require a miRNA of interest to be defined in assays such as northern blotting, microarray, and qPCR. Therefore, the expression of many miRNAs and their isoforms have not been studied during early development. Here, we demonstrate a protocol for small RNA sequencing of sorted cells from early mouse embryos to enable relatively unbiased profiling of miRNAs in early populations of neural crest cells. We overcome the challenges of low cell input and size selection during library preparation using amplification and gel-based purification. We identify embryonic age as a variable accounting for variation between replicates and stage-matched mouse embryos must be used to accurately profile miRNAs in biological replicates. Our results suggest that this method can be broadly applied to profile the expression of miRNAs from other lineages of cells. In summary, this protocol can be used to study how miRNAs regulate developmental programs in different cell lineages of the early mouse embryo.

We describe a technique for profiling microRNAs in early mouse embryos. This protocol overcomes the challenge of low cell input and small RNA enrichment. This assay can be used to analyze changes in miRNA expression over time in different cell lineages of the early mouse embryo.

MicroRNAs (miRNAs) are important for the complex regulation of cell fate decisions and developmental timing. In vivo studies of the contribution of miRNAs ...

A Protocol for Immunohistochemistry and RNA In-situ Distribution within Early Drosophila Embryo

Calcium induced calcium release signaling (CICR) plays a critical role in many biological processes. Every cellular activity from cell proliferation and apoptosis, development and ageing, to neuronal synaptic plasticity and regeneration have been associated with Ryanodine receptors (RyRs). Despite the importance of calcium signaling, the exact mechanism of its function in early development is unclear. As an organism with a short gestational period, the embryos of Drosophila melanogaster are prime study subjects for investigating the distribution and localization of CICR associated proteins and their regulators during development. However, because of their lipid-rich embryos and chitin-rich chorion, their utility is limited by the difficulty of mounting embryos on glass surfaces. In this work, we introduce a practical protocol that significantly enhances the attachment of Drosophila embryo onto slides and detail methods for successful histochemistry, immunohistochemistry, and in-situ hybridization. The chrome alum gelatin slide-coating method and embryo pre-embedding method dramatically increases the yield in studying Drosophila embryo protein and RNA expression. To demonstrate this approach, we studied DmFKBP12/Calstabin, a well-known regulator of RyR during early embryonic development of Drosophila melanogaster. We identified DmFKBP12 in as early as the syncytial blastoderm stage and report the dynamic expression pattern of DmFKBP12 during development: initially as an evenly distributed protein in the syncytial blastoderm, then preliminarily localizing to the basement layer of the cortex during cellular blastoderm, before distributing in the primitive neuronal and digestion architecture during the three-gem layer phase in early gastrulation. This distribution may explain the critical role RyR plays in the vital organ systems that originate in from these layers: the suboesophageal and supraesophageal ganglion, ventral nervous system, and musculoskeletal system.

A Protocol for Immunohistochemistry and RNA In-situ Distribution within Early Drosophila Embryo

Here, we describe a protocol for detection and localization of Drosophila embryo protein and RNA from collection to pre-embedding and embedding, immunostaining, and mRNA in situ hybridization.

Calcium induced calcium release signaling (CICR) plays a critical role in many biological processes. Every cellular activity from cell proliferation and ...

2D and 3D Human Induced Pluripotent Stem Cell-Based Models to Dissect Primary Cilium Involvement during Neocortical Development

Primary cilia (PC) are non-motile dynamic microtubule-based organelles that protrude from the surface of most mammalian cells. They emerge from the older centriole during the G1/G0 phase of the cell cycle, while they disassemble as the cells re-enter the cell cycle at the G2/M phase boundary. They function as signal hubs, by detecting and transducing extracellular signals crucial for many cell processes. Similar to most cell types, all neocortical neural stem and progenitor cells (NSPCs) have been shown harboring a PC allowing them to sense and transduce specific signals required for the normal cerebral cortical development. Here, we provide detailed protocols to generate and characterize two-dimensional (2D) and three-dimensional (3D) cell-based models from human induced pluripotent stem cells (hIPSCs) to further dissect the involvement of PC during neocortical development. In particular, we present protocols to study the PC biogenesis and function in 2D neural rosette-derived NSPCs including the transduction of the Sonic Hedgehog (SHH) pathway. To take advantage of the three-dimensional (3D) organization of cerebral organoids, we describe a simple method for 3D imaging of in toto immunostained cerebral organoids. After optical clearing, rapid acquisition of entire organoids allows detection of both centrosomes and PC on neocortical progenitors and neurons of the whole organoid. Finally, we detail the procedure for immunostaining and clearing of thick free-floating organoid sections preserving a significant degree of 3D spatial information and allowing for the high-resolution acquisition required for the detailed qualitative and quantitative analysis of PC biogenesis and function.

We present detailed protocols for the generation and characterization of 2D and 3D human induced pluripotent stem cell (hIPSC)-based models of neocortical development as well as complementary methodologies enabling qualitative and quantitative analysis of primary cilium (PC) biogenesis and function.

Primary cilia (PC) are non-motile dynamic microtubule-based organelles that protrude from the surface of most mammalian cells. They emerge from the older ...