Name: development of targeting induced local lesions in genomes (tilling) populations in small grain crops by ethyl methanesulfonate mutagenesis
Uploaded: 2019-07-16T13:00:00
Description: Watch this Scientific Journal Video about Development of Targeting Induced Local Lesions IN Genomes TILLING Populations in Small Grain Crops by Ethyl Methanesulfonate Mutagenesis at JoVE.com

This work was supported by the USDA National Institute of Food and Agriculture, Hatch project 1016879 and Maryland Agricultural Experiment Station via MAES Grant No. 2956952.

1. Preparation of dosage curve for effective mutagenesis
<ol>
	<li>Soak 100 seeds with the genotype of interest in six 250 mL glass flasks (100 in each flask) containing 50 mL of distilled water. Shake at 100 rpm for 8 h at room temperature (RT) for imbibition by the seeds.</li>
	<li>In a fume hood, prepare 50 mL of 0.4%, 0.6%, 0.8%, 1.0%, and 1.2% (w/v) ethyl methanesulfonate (EMS) solution by dissolving 0.167, 0.249, 0.331, 0.415, and 0.498 mL of EMS in distilled water, respectively. 
	NOTE: EMS is liquid at RT ...

<ol>
	<li>McCallum, C. M., Comai, L., Greene, E. A., Henikoff, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+screening+for+induced+mutations.">Targeted screening for induced mutations.</a> Nature Biotechnology. 18 (4), 455-457 (2000).</li><li>Bentley, A., MacLennan, B., Calvo, J., Dearolf, C. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+and+remaining+challenges+in+the+transformation+of+barley+and+wheat.">Advances and remaining challenges in the transformation of barley and wheat.</a> Journal of Experimental Botany. 63 (5), 1791-1798 (2012).</li><li>Henikoff, S., Comai, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-Nucleotide+Mutations+for+Plant+Functional+Genomics.">Single-Nucleotide Mutations for Plant Functional Genomics.</a> Annual Review of Plant Biology. 54 (1), 375-401 (2003).</li><li>Uauy, 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=A+modified+TILLING+approach+to+detect+induced+mutations+in+tetraploid+and+hexaploid+wheat.">A modified TILLING approach to detect induced mutations in tetraploid and hexaploid wheat.</a> BMC Plant Biology. 9 (1), 115 (2009).</li><li>Uauy, C., Wulff, B. 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H., Dubcovsky, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combining+Traditional+Mutagenesis+with+New+High-Throughput+Sequencing+and+Genome+Editing+to+Reveal+Hidden+Variation+in+Polyploid+Wheat.">Combining Traditional Mutagenesis with New High-Throughput Sequencing and Genome Editing to Reveal Hidden Variation in Polyploid Wheat.</a> Annual Review of Genetics. 51 (1), 435-454 (2017).</li><li>Li, G., 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=The+Sequences+of+1504+Mutants+in+the+Model+Rice+Variety+Kitaake+Facilitate+Rapid+Functional+Genomic+Studies.">The Sequences of 1504 Mutants in the Model Rice Variety Kitaake Facilitate Rapid Functional Genomic Studies.</a> The Plant Cell. 29 (6), 1218-1231 (2017).</li><li>Jiao, 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+Sorghum+Mutant+Resource+as+an+Efficient+Platform+for+Gene+Discovery+in+Grasses.">A Sorghum Mutant Resource as an Efficient Platform for Gene Discovery in Grasses.</a> The Plant Cell. 28 (7), 1551-1562 (2016).</li><li>Krasileva, K. V., 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=Uncovering+hidden+variation+in+polyploid+wheat.">Uncovering hidden variation in polyploid wheat.</a> Proceedings of the National Academy of Sciences. , 201619268 (2017).</li><li>Dong, C., Dalton-Morgan, J., Vincent, K., Sharp, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Modified+TILLING+Method+for+Wheat+Breeding.">A Modified TILLING Method for Wheat Breeding.</a> The Plant Genome. 2 (1), 39-47 (2009).</li><li>Till, B. J., Zerr, T., Comai, L., Henikoff, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+protocol+for+TILLING+and+Ecotilling+in+plants+and+animals.">A protocol for TILLING and Ecotilling in plants and animals.</a> Nature Protocols. 1 (5), 2465-2477 (2006).</li><li>Wu, J. -. L., 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=Chemical-+and+Irradiation-induced+Mutants+of+Indica+Rice+IR64+for+Forward+and+Reverse+Genetics.">Chemical- and Irradiation-induced Mutants of Indica Rice IR64 for Forward and Reverse Genetics.</a> Plant Molecular Biology. 59 (1), 85-97 (2005).</li><li>Feldman, M., Levy, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+Evolution+Due+to+Allopolyploidization+in+Wheat.">Genome Evolution Due to Allopolyploidization in Wheat.</a> Genetics. 192 (3), 763-774 (2012).</li><li>Comai, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+advantages+and+disadvantages+of+being+polyploid.">The advantages and disadvantages of being polyploid.</a> Nature Reviews Genetics. 6 (11), 836-846 (2005).</li><li>Guo, 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=Development+of+a+High-Efficient+Mutation+Resource+with+Phenotypic+Variation+in+Hexaploid+Winter+Wheat+and+Identification+of+Novel+Alleles+in+the+TaAGP.L-B1+Gene.">Development of a High-Efficient Mutation Resource with Phenotypic Variation in Hexaploid Winter Wheat and Identification of Novel Alleles in the TaAGP.L-B1 Gene.</a> Frontiers in Plant Science. 8, (2017).</li><li>Rakszegi, 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=Diversity+of+agronomic+and+morphological+traits+in+a+mutant+population+of+bread+wheat+studied+in+the+Healthgrain+program.">Diversity of agronomic and morphological traits in a mutant population of bread wheat studied in the Healthgrain program.</a> Euphytica. 174 (3), 409-421 (2010).</li><li>Tsai, H., Ngo, K., Lieberman, M., Missirian, V., Comai, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tilling+by+Sequencing.">Tilling by Sequencing.</a> Plant Functional Genomics: Methods and Protocols. , 359-380 (2015).</li></ol>

TILLING is a highly valuable reverse genetics tool for gene validation, especially for small grains where transformation-based approaches have serious bottlenecks11. Developing a mutagenized population with a high mutation frequency is one of the critical steps in conducting functional genomics studies. The most important step in developing a robust TILLING population is to determine the optimal concentration of EMS. The 40%-60% survival rate in the M1 has been found to be a good indica...

Point mutations in genomes can serve many useful purposes for researchers. Depending on their nature and location, these mutations can be used to assign functions to genes or even distinct domains of proteins of interest. On the other hand, as a source of novel genetic variation, useful mutations can be selected for desired traits using phenotyping screens and further used in crop improvement. TILLING is a powerful reverse genetics tool that includes chemical mutagenesis and detection of sequence variation in the target gene. First developed in Arabidopsis1 and Drosophilia melanogaster2, TILLING populations have been developed and utilized in many small grain crops such as hexaploid bread wheat (Triticum aestivum)3, barley (Hordeum vulgare)4, tetraploid durum wheat (T. dicoccoides durum)5, diploid wheat (T. monococcum)6 and the &#34;D&#34; genome progenitor of wheat Aegilops tauschii7. These resources have been used to validate the roles of genes in regulating abiotic and biotic stress tolerance8, regulating flowering time9, and developing nutritionally superior crop varieties5.
TILLING, along with the use of alkylating mutagenic agents such as ethyl methanesulfonate (EMS), sodium azide, N-methyl-N-nitrosourea (MNU), and methyl methanesulfonate (MMS), has advantages over other reverse genetics tools for several reasons. First, mutagenesis can be conducted on practically any species or variety of plant10 and is independent of the transformation bottleneck, which is particularly challenging in the case of small grains11. Second, in addition to generating knockout mutations that can be obtained by other gene validation approaches, a range of missense and splicing mutations can be induced, which can discern functions of individual domains of the proteins of interest12. Moreover, TILLING generates an immortal collection of mutations throughout the genome; thus, a single population can be used for functional validation of multiple genes. In contrast, other reverse genetics tools generate resources specific to only the gene under study13. Useful mutations identified through TILLING can be deployed for breeding purposes and are not subject to regulation, unlike gene editing, whose non-transgenic classification is still uncertain in many countries. This becomes especially relevant to small grains that are internationally traded14.
TILLING is a simple and efficient gene validation strategy and requires mutagenized populations to be developed for investigating genes of interest. Developing an effective mutagenized population is key to determining the efficiency of a TILLING-based gene validation study. A TILLING population with a low overall mutation frequency indicates that an impractically large population must be screened for desired mutations, whereas a high mutagen concentration leads to high mortality in the population and an insufficient number of mutagenized individuals. Once a good population is developed, there are multiple ways to detect mutations in the genes of interest, and the choice of platform depends on the experimental scale and availability of resources. Whole genome sequencing and exome sequencing has been used to characterize all mutations in TILLING populations in plants with small genomes15,16. Exome sequencing of two TILLING populations has been performed in bread and durum wheat and is available to the public for identifying desirable mutations and ordering mutant lines of interest17. It is a great public resource in terms of availability of desirable mutations; however, in gene validation studies, the wild-type line should possess the candidate gene of interest. Unfortunately, it is still cost-prohibitive to sequence the exome of the entire TILLING population for reverse genetics-based validation of a few candidate genes in another background. Amplicon sequencing and Cel-1-based assays have been used in detecting mutations in targeted populations in wheat, and Cel-1 assays are simpler, requiring no computational knowledge, and are especially suitable for validation of a small number of genes with basic lab equipment6,18.
In the present article, described are methods for the development of a good TILLING population, including preparation of the dosage curve, mutagenesis and maintenance of the mutant population, and screening of the mutant population using the PCR-based Cel-1 assay. This protocol has already been implemented successfully in developing and utilizing mutagenized populations of Triticum aestivum, Triticum monoccocum6, barley, Aegilops tauchii7, and several others. Included are explicit details of these methods along with useful tips that will help researchers develop TILLING populations, using EMS as a mutagen in any small grain plant of choice.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96 well 1.1 ml microtubes in microracks</td>
			<td>National Scientific</td>
			<td>TN0946-08R</td>
			<td>For collecting leaf tissues</td>
		</tr>
		<tr>
			<td>Agarose I biotechnology grade</td>
			<td>VWR</td>
			<td>0710-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Biosprint 96 DNA Plant Kit</td>
			<td>Qiagen</td>
			<td>941558</td>
			<td>Kit for DNA extraction</td>
		</tr>
		<tr>
			<td>Cel-1 endonuclease</td>
			<td>Extracted as described by Till et al 2006</td>
			<td></td>
			<td>Single strand specific endonuclease</td>
		</tr>
		<tr>
			<td>Centrifuge 5430 R</td>
			<td>Eppendorf</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl methanesulfonate</td>
			<td>Sigma Aldrich</td>
			<td>M-0880-25G</td>
			<td>EMS, Chemical mutagen</td>
		</tr>
		<tr>
			<td>Freeze Dry/Shell freeze system</td>
			<td>Labconco</td>
			<td></td>
			<td>For lyophilization of leaf tissue</td>
		</tr>
		<tr>
			<td>Kingfisher Flex purification system</td>
			<td>Thermo fisher scientific</td>
			<td>5400610</td>
			<td>High throughput DNA extraction robot</td>
		</tr>
		<tr>
			<td>My Taq DNA Polymerase</td>
			<td>Bioline</td>
			<td>BIO-21107</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease free water</td>
			<td>Sigma aldrich</td>
			<td>W4502-1L</td>
			<td></td>
		</tr>
		<tr>
			<td>NuGenius gel imaging system</td>
			<td>Syngene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Orbit Environ-shaker</td>
			<td>Lab-line</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SPECTROstar Nano</td>
			<td>BMG LABTECH</td>
			<td></td>
			<td>Nano drop for DNA quantification</td>
		</tr>
		<tr>
			<td>T100 Thermal cycler</td>
			<td>BIO-RAD</td>
			<td>1861096</td>
			<td></td>
		</tr>
	</tbody>
</table>

development of targeting induced local lesions in genomes (tilling) populations in small grain crops by ethyl methanesulfonate mutagenesis

Targeting Induced Local Lesions IN Genomes (TILLING) is a powerful reverse genetics tool that includes chemical mutagenesis and detection of sequence variation in target genes. TILLING is a highly valuable functional genomics tool for gene validation, especially in small grains in which transformation-based approaches hold serious limitations. Developing a robust mutagenized population is key to determining the efficiency of a TILLING-based gene validation study. A TILLING population with a low overall mutation frequency indicates that an impractically large population must be screened to find desired mutations, whereas a high mutagen concentration leads to high mortality in the population, leading to an insufficient number of mutagenized individuals. Once an effective population is developed, there are multiple ways to detect mutations in a gene of interest, and the choice of platform depends upon the experimental scale and availability of resources. The Cel-1 assay and agarose gel-based approach for mutant identification is convenient, reproducible, and a less resource-intensive platform. It is advantageous in that it is simple, requiring no computational knowledge, and it is especially suitable for validation of a small number of genes with basic lab equipment. In the present article, described are the methods for development of a good TILLING population, including preparation of the dosage curve, mutagenesis and maintenance of the mutant population, and screening of the mutant population using the PCR-based Cel-1 assay.

Figure 2 shows the dosage curve of hexaploid bread wheat cultivar Jagger, diploid wheat Triticum monococcum6, and a genome donor of wheat Aegilops tauschii7. The EMS doses for desired 50% survival rates were about 0.25%, 0.6% and 0.7% for T. monococcum, Ae. tauschii, and T. aestivum, respectively. The higher EMS tolerance of hexaploid wheat is due to its genome buffer...

Watch this Scientific Journal Video about Development of Targeting Induced Local Lesions IN Genomes TILLING Populations in Small Grain Crops by Ethyl Methanesulfonate Mutagenesis at JoVE.com

Development of Targeting Induced Local Lesions IN Genomes TILLING Populations in Small Grain Crops by Ethyl Methanesulfonate Mutagenesis

Described is a protocol for developing a Targeting Induced Local Lesions IN Genomes (TILLING) population in small grain crops with use of ethyl methanesulfonate (EMS) as a mutagen. Also provided is a protocol for mutation detection using the Cel-1 assay.

Development of Targeting Induced Local Lesions IN Genomes (TILLING) Populations in Small Grain Crops by Ethyl Methanesulfonate Mutagenesis

Targeting Induced Local Lesions IN Genomes (TILLING) is a powerful reverse genetics tool that includes chemical mutagenesis and detection of sequence ...

This protocol details the development of robust TILLING populations with high mutation frequency by EMS mutagenesis in small grain crops. TILLING populations can be used for functional genomics, as well as for forward genetic space gene discovery in small grain crops. The TILLING populations developed using this technique have high mutation frequencies, and this protocol can be applied to any genotype.The Cel-1 assay based mutation detection can be conducted using basic lab equipments. The most important step is to determine the optimal EMS concentration. Therefore, an EMS dosage curve should be made specifically for the individual population.To begin, soak 100 seeds with the genotype of interest in each of six 250 milliliter glass flasks, containing 50 milliliters of distilled water. Shake at 100 RPM for eight hours at room temperature for imbibition. Then, in a fume hood, prepare 50 milliliters of EMS solutions of five different concentrations by mixing EMS liquid and distilled water.After imbibition, decant the water out of five flasks. Add 50 milliliters of EMS solution in each of the five flasks containing imbibed seeds. Shake the flasks for 16 hours at 75 RPM and room temperature.Now, decant the EMS solution into an empty waste bottle and pour the treated seeds onto cheesecloth placed on an empty waste bottle to collect separately for each treatment. Use extra water to help pouring of the seeds. Also, spray several milliliters of EMS inactivating solution onto the wall of contaminated flasks.And immerse used pipette tips in the solution for 24 hours. Inactive the used EMS solution by adding one volume of EMS inactivating solution to treat for 24 hours. Using a twist tie, hold the EMS treated seeds inside the cheesecloth and wash under running tap water for two hours.After washing, transplant each seed individually into root trainers containing potting soil. Grow plants at 20 to 25 degrees Celsius for a 16 hour light period. After 15 days of transplantation, check the plants and count the number of seeds that failed to germinate.Record data of plant survival. If the survival rate is not within 40 to 60%conduct a second round of dosage optimization with a modified concentration until achieving the desired lethality rate of 40 to 60%After the mutagenesis experiment, collect the leaf tissue of M2 plants in a 96 well tissue collection box. Tissue is collected from M2 plants which were grown from selfed M1 plants.One M2 plant is shown from each M1 plant. Extract DNA using a plant DNA extraction kit with a DNA purification system following the manufacturer's recommendations. Then, load two microliters of the DNA extract into LV plates with 16 slots.Quantify DNA using a spectrophotometer at wavelengths of 260 and 280 nanometers. Dilute the DNA concentration to 25 nanograms per microliter with nuclease-free water. Create four times DNA pools of 200 microliters by combining the DNA from each well in the four 96 well blocks into a pool plate while maintaining the row and column identity of each sample.Next, prepare a PCR master mix tube for gene specific primers by adding into each tube PCR buffer, forward and reverse primers, and DNA polymerase according to the manuscript. Aliquot the master mix into the wells of a 96 well PCR plate. Then, add the pooled DNA template.Load the PCR tubes into a thermal cycler, and use a touchdown profile to run the PCR reaction on the thermal cycler. To generate heteroduplexes between mismatched DNAs, incubate PCR products in the thermal cycler in a different program. Then, add 2.5 microliters of homemade Cel-1 endonuclease to each of the heteroduplexed PCR products.Incubate for 45 minutes at 45 degrees Celsius. After that, terminate the Cel-1 reaction by adding 2.5 microliters of 0.5 molar EDTA at pH eight. Load 30.5 microliters of each Cel-1 treated product mixed with five microliters of dye onto a 3%agarose gel and run at 100 volts for two and a half hours.To deconvolute mutant pools, determine the zygosity of mutants by running two PCR reactions for individual M2 DNA in which the first reaction contains 2.5 microliters of M2 DNA and 2.5 microliters of wild type DNA and the second reaction contains only five microliters of M2 DNA. This protocol shows EMS mutagenizing of small grain crops and the characterization of mutant. The dosage curve indicates optimal EMS doses for the desired 50%survival rates for three different species of wheat.The presence of easily identifiable phenotypes in the M2 population confirms effectiveness of mutagenesis in small grain populations. Here are four examples of the mutant phenotypes in M2 TILLING populations, an albino mutant in a barley M2 population, a chlorina mutant in a barley M2 population, a variegated mutant with pink discoloration in an Aegilops tauschii M2 population, and a low-tillering mutant in a Triticum monococcum M2 population. A mutant identification using Cel-1 on agarose gel platforms shows a potential mutant pool identified out of 12 mutant pools by unique cleaved bands.The deconvolution of mutant pools determined the zygosity of mutation and helped to track the mutation down to individual samples. The A4 pool had heterozygous mutations, indicated by cleaved bands in both Box 4 and Box 4 wild type DNA samples. The H5 pool contained homozygous mutations as unique cleaved bands were only present in Box 5 H5 wild type DNA sample.The most important step is to determine the optimal concentration of EMS to achieve 40 to 60%lethality rate. Once a TILLING population with a high mutation frequency has been developed it can be used for functional characterization of any gene of interest. Additionally, the population can be a source of useful genetic variation for crop improvement.TILLING has been used extensively for functional genomic studies in model and crop plants. The range of mutations obtained can be missents, knockouts, silent, or even misspliced forms. EMS is a mutagen.Therefore, use appropriate personal protective equipment while handling the EMS. Decontaminate leftover solutions and used pipette tips.

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Kidney Regeneration in Adult Zebrafish by Gentamicin Induced Injury

The kidney is essential for fluid homeostasis, blood pressure regulation and filtration of waste from the body. The fundamental unit of kidney function is the nephron. Mammals are able to repair existing nephrons after injury, but lose the ability to form new nephrons soon after birth. In contrast to mammals, adult fish produce new nephrons (neonephrogenesis) throughout their lives in response to growth requirements or injury. Recently, lhx1a has been shown to mark nephron progenitor cells in the adult zebrafish kidney, however mechanisms controlling the formation of new nephrons after injury remain unknown. Here we show our method for robust and reproducible injury in the adult zebrafish kidney by intraperitoneal (i.p.) injection of gentamicin, which uses a noninvasive visual screening process to select for fish with strong but nonlethal injury. Using this method, we can determine optimal gentamicin dosages for injury and go on to demonstrate the effect of higher temperatures on kidney regeneration in zebrafish.

Here we present a reliable method to study adult kidney regeneration by inducing acute kidney injury by gentamicin injection. We show that injury is dependent on gentamicin dosage and environmental temperature using in situ hybridization to label lhx1a+ developing new nephrons.

The kidney is essential for fluid homeostasis, blood pressure regulation and filtration of waste from the body. The fundamental unit of kidney function is ...

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays

Characterizing thymic settling progenitors is important to understand the pre-thymic stages of T cell development, essential to devise strategies for T cell replacement in lymphopenic patients. We studied thymic settling progenitors from murine embryonic day 13 and 18 thymi by two complementary in vitro and in vivo techniques, both based on the &#8220;hanging drop&#8221; method. This method allowed colonizing irradiated fetal thymic lobes with E13 and/or E18 thymic progenitors distinguished by CD45 allotypic markers and thus following their progeny. Colonization with mixed populations allows analyzing cell autonomous differences in biologic properties of the progenitors while colonization with either population removes possible competitive selective pressures. The colonized thymic lobes can also be grafted in immunodeficient male recipient mice allowing the analysis of the mature T cell progeny in vivo, such as population dynamics of the peripheral immune system and colonization of different tissues and organs. Fetal thymic organ cultures revealed that E13 progenitors developed rapidly into all mature CD3+ cells and gave rise to the canonical &#947;&#948; T cell subset, known as dendritic epithelial T cells. In comparison, E18 progenitors have a delayed differentiation and were unable to generate dendritic epithelial T cells. The monitoring of peripheral blood of thymus-grafted CD3-/- mice further showed that E18 thymic settling progenitors generate, with time, larger numbers of mature T cells than their E13 counterparts, a feature that could not be appreciated in the short term fetal thymic organ cultures.

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays

This article describes in vivo and in vitro methodology to characterize the thymic settling progenitors by the analysis of the kinetics of generation, phenotype and numbers of their T cell progeny.

Characterizing thymic settling progenitors is important to understand the pre-thymic stages of T cell development, essential to devise strategies for T ...

Analysis of Zebrafish Larvae Skeletal Muscle Integrity with Evans Blue Dye

The zebrafish model is an emerging system for the study of neuromuscular disorders. In the study of neuromuscular diseases, the integrity of the muscle membrane is a critical disease determinant. To date, numerous neuromuscular conditions display degenerating muscle fibers with abnormal membrane integrity; this is most commonly observed in muscular dystrophies. Evans Blue Dye (EBD) is a vital, cell permeable dye that is rapidly taken into degenerating, damaged, or apoptotic cells; in contrast, it is not taken up by cells with an intact membrane. EBD injection is commonly employed to ascertain muscle integrity in mouse models of neuromuscular diseases. However, such EBD experiments require muscle dissection and/or sectioning prior to analysis. In contrast, EBD uptake in zebrafish is visualized in live, intact preparations. Here, we demonstrate a simple and straightforward methodology for performing EBD injections and analysis in live zebrafish. In addition, we demonstrate a co-injection strategy to increase efficacy of EBD analysis. Overall, this video article provides an outline to perform EBD injection and characterization in zebrafish models of neuromuscular disease.

In this study, we describe a straightforward method to perform Evans Blue Dye (EBD) analysis on zebrafish larvae. This technique is a powerful tool for the characterization of skeletal muscle integrity and delineation of zebrafish models of muscular dystrophy, and is a valuable method for the development of novel therapeutics.

The zebrafish model is an emerging system for the study of neuromuscular disorders.  In the study of neuromuscular diseases, the integrity of the muscle ...

Technique to Target Microinjection to the Developing Xenopus Kidney

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus embryos are large, develop externally, and can be easily manipulated by microinjection or surgical procedures. In addition, fate maps have been established for early Xenopus embryos. Targeted microinjection into the individual blastomere that will eventually give rise to an organ or tissue of interest can be used to selectively overexpress or knock down gene expression within this restricted region, decreasing secondary effects in the rest of the developing embryo. In this protocol, we describe how to utilize established Xenopus fate maps to target the developing Xenopus kidney (the pronephros), through microinjection into specific blastomere of 4- and 8-cell embryos. Injection of lineage tracers allows verification of the specific targeting of the injection. After embryos have developed to stage 38 - 40, whole-mount immunostaining is used to visualize pronephric development, and the contribution by targeted cells to the pronephros can be assessed. The same technique can be adapted to target other tissue types in addition to the pronephros.

Technique to Target Microinjection to the Developing Xenopus Kidney

Here, we present a protocol to use fate maps and lineage tracers to target injections into individual blastomeres that give rise to the kidney of Xenopus laevis embryos.

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus ...

Development of an Ethanol-induced Fibrotic Liver Model in Zebrafish to Study Progenitor Cell-mediated Hepatocyte Regeneration

Sustained liver fibrosis with continuation of extracellular matrix (ECM) protein build-up results in the loss of cellular competency of the liver, leading to cirrhosis with hepatocellular dysfunction. Among multiple hepatic insults, alcohol abuse can lead to significant health problems including liver failure and hepatocellular carcinoma. Nonetheless, the identity of endogenous cellular sources that regenerate hepatocytes in response to alcohol has not been properly investigated. Moreover, few studies have effectively modeled hepatocyte regeneration upon alcohol-induced injury. We recently reported on establishing an ethanol (EtOH)-induced fibrotic liver model in zebrafish in which hepatic progenitor cells (HPCs) gave rise to hepatocytes upon near-complete hepatocyte loss in the presence of fibrogenic stimulus. Furthermore, through chemical screens using this model, we identified multiple small molecules that enhance hepatocyte regeneration. Here we describe in detail the procedures to develop an EtOH-induced fibrotic liver model and to perform chemical screens using this model in zebrafish. This protocol will be a critical tool to delineate the molecular and cellular mechanisms of how hepatocyte regenerates in the fibrotic liver. Furthermore, these methods will facilitate potential discovery of novel therapeutic strategies for chronic liver disease in vivo.

Sustained fibrosis with deposition of excessive extracellular matrix proteins leads to cirrhosis. Alcohol abuse is one of the main causes of severe liver disease. We established an ethanol-induced zebrafish fibrotic liver model to study the mechanisms and strategies of promoting hepatocyte regeneration upon alcohol-induced injury.

Sustained liver fibrosis with continuation of extracellular matrix (ECM) protein build-up results in the loss of cellular competency of the liver, leading ...

Quantitative Whole-mount Immunofluorescence Analysis of Cardiac Progenitor Populations in Mouse Embryos

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development and organogenesis are two areas of research that have benefitted greatly from these advances, due to the high quality of data that can be obtained directly from imaging pre-implantation embryos or ex vivo organs. While pre-implantation embryos have yielded data with especially high spatial resolution, later stages have been less amenable to three-dimensional reconstruction. Obtaining high-quality 3D or volumetric data for known embryonic structures in combination with fate mapping or genetic lineage tracing will allow for a more comprehensive analysis of the morphogenetic events taking place during embryogenesis.
This protocol describes a whole-mount immunofluorescence approach that allows for the labeling, visualization, and quantification of progenitor cell populations within the developing cardiac crescent, a key structure formed during heart development. The approach is designed in such a way that both cell- and tissue-level information can be obtained. Using confocal microscopy and image processing, this protocol allows for three-dimensional spatial reconstruction of the cardiac crescent, thereby providing the ability to analyze the localization and organization of specific progenitor populations during this critical phase of heart development. Importantly, the use of reference antibodies allows for successive masking of the cardiac crescent and subsequent quantitative measurements of areas within the crescent. This protocol will not only enable a detailed examination of early heart development, but with adaptations should be applicable to most organ systems in the gastrula to early somite stage mouse embryo.

Here, we describe a protocol for whole mount immunofluorescence and image-based quantitative volumetric analysis of early stage mouse embryos. We present this technique as a powerful approach to qualitatively and quantitatively assess cardiac structures during development, and propose that it may be widely adaptable to other organ systems.

The use of ever-advancing imaging techniques has contributed broadly to our increased understanding of embryonic development. Pre-implantation development ...

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain and protect cellular identities. The conversion of germ cells into specific neurons in the nematode Caenorhabditis elegans (C. elegans) is a powerful tool for performing genetic screens in order to dissect regulatory pathways that safeguard established cell identities. Reprogramming of germ cells to a specific type of neurons termed ASE requires transgenic animals that allow broad over-expression of the Zn-finger transcription factor (TF) CHE-1. Endogenous CHE-1 is expressed exclusively in two head neurons and is required to specify the glutamatergic ASE neurons fate, which can easily be visualized by the gcy-5prom::gfp reporter. A trans gene containing the heat-shock promoter-driven che-1 gene expression construct allows broad mis-expression of CHE-1 in the entire animal upon heat-shock treatment. The combination of RNAi against the chromatin-regulating factor LIN-53 and heat-shock-induced che-1 over-expression leads to reprogramming of germ cell into ASE neuron-like cells. We describe here the specific RNAi procedure and appropriate conditions for heat-shock treatment of transgenic animals in order to successfully induce germ cell to neuron conversion.

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

This protocol describes how to study cellular processes during cell fate conversion in Caenorhabditis elegans in vivo. Using transgenic animals, allowing heat-shock promoter-driven overexpression of the neuron fate-inducing transcription factor CHE-1 and RNAi-mediated depletion of the chromatin-regulating factor LIN-53 germ cell to neuron reprogramming can be observed in vivo.

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain ...

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the Notch receptor with ligands from neighboring cells induces activation of the signaling pathway (trans-activation), while interaction with ligands from the same cell inhibits signaling (cis-inhibition). Proper balance between trans-activation and cis-inhibition helps establish optimal levels of Notch signaling in some contexts during animal development. Because of the overlapping expression domains of Notch and its ligands in many cell types and the existence of feedback mechanisms, studying the effects of a given post-translational modification on trans- versus cis-interactions of Notch and its ligands in vivo is difficult. Here, we describe a protocol for using Drosophila S2 cells in cell-aggregation assays to assess the effects of knocking down a Notch pathway modifier on the binding of Notch to each ligand in trans and in cis. S2 cells stably or transiently transfected with a Notch-expressing vector are mixed with cells expressing each Notch ligand (S2-Delta or S2-Serrate). Trans-binding between the receptor and ligands results in the formation of heterotypic cell aggregates and is measured in terms of the number of aggregates per mL composed of &#62;6 cells. To examine the inhibitory effect of cis-ligands, S2 cells co-expressing Notch and each ligand are mixed with S2-Delta or S2-Serrate cells and the number of aggregates is quantified as described above. The relative decrease in the number of aggregates due to the presence of cis-ligands provides a measure of cis-ligand-mediated inhibition of trans-binding. These straightforward assays can provide semi-quantitative data on the effects of genetic or pharmacological manipulations on the binding of Notch to its ligands, and can help deciphering the molecular mechanisms underlying the in vivo effects of such manipulations on Notch signaling.

Cell Aggregation Assays to Evaluate the Binding of the Drosophila Notch with Trans-Ligands and its Inhibition by Cis-Ligands

Complexity of in vivo systems makes it difficult to distinguish between the activation and inhibition of Notch receptor by trans- and cis-ligands, respectively. Here, we present a protocol based on in vitro cell-aggregation assays for qualitative and semi-quantitative evaluation of the binding of Drosophila Notch to trans-ligands vs cis-ligands.

Notch signaling is an evolutionarily conserved cell-cell communication system used broadly in animal development and adult maintenance. Interaction of the ...

Controlled Cortical Impact Model of Mouse Brain Injury with Therapeutic Transplantation of Human Induced Pluripotent Stem Cell-Derived Neural Cells

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical insult to secondary injury processes, including apoptosis and inflammation. Animal modeling has been valuable in the search to unravel injury mechanisms and evaluate potential neuroprotective therapies. This protocol describes the controlled cortical impact (CCI) model of focal, open-head TBI. Specifically, parameters for producing a mild unilateral cortical injury are described. Behavioral consequences of CCI are analyzed using the adhesive tape removal test of bilateral sensorimotor integration. Regarding experimental therapy for TBI pathology, this protocol also illustrates a process for transplanting cultured cells into the brain. Neural cell cultures derived from human induced pluripotent stem cells (hiPSCs) were chosen for their potential to show superior functional restoration in human TBI patients. Chronic survival of hiPSCs in the host mouse brain tissue is detected using a modified DAB immunohistochemical process.

This protocol demonstrates methodologies for a mouse model of open-skull traumatic brain injury and transplantation of cultured human induced pluripotent stem cell-derived cells into the injury site. Behavioral and histologic tests of outcomes from these procedures are also described in brief.

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical ...

Murine Neural Plate Targeting by In Utero Nano-Injection (NEPTUNE) at Embryonic Day 7.5

Manipulating gene expression in the developing mouse brain in utero holds great potential for functional genetics studies. However, it has previously largely been restricted to the manipulation of embryonic stages post-neurulation. A protocol was developed to inject the amniotic cavity at embryonic day (E)7.5 and deliver lentivirus, encoding cDNA or shRNA, targeting &gt;95% of the neural plate and neural crest cells, contributing to the future brain, spinal cord, and peripheral nervous system. This protocol describes the steps necessary to achieve successful transduction, including grinding of the glass capillary needles, pregnancy verification, developmental staging using ultrasound imaging, and optimal injection volumes matched to embryonic stages. 
Following this protocol, it is possible to achieve transduction of &gt;95% of the developing brain with high-titer lentivirus and thus perform whole-brain genetic manipulation. In contrast, it is possible to achieve mosaic transduction using lower viral titers, allowing for genetic screening or lineage tracing. Injection at E7.5 also targets ectoderm and neural crest contributing to distinct compartments of the eye, tongue, and peripheral nervous system. This technique thus offers the possibility to manipulate gene expression in mouse neural-plate- and ectoderm-derived tissues from preneurulation stages, with the benefit of reducing the number of mice used in experiments.

Murine Neural Plate Targeting by In Utero Nano-Injection NEPTUNE at Embryonic Day 7.5

In this protocol, we describe how to inject the mouse amniotic cavity at E7.5 with lentivirus, leading to uniform transduction of the entire neural plate, with minimal detrimental effects on survival or embryonic development.

Manipulating gene expression in the developing mouse brain in utero holds great potential for functional genetics studies. However, it has previously ...