Name: zygotic fluorescence recovery after photo-bleaching analysis for chromatin looseness that allows full-term development
Uploaded: 2018-06-12T14:30:00
Description: Watch this Scientific Journal Video about Zygotic Fluorescence Recovery After Photo-bleaching Analysis for Chromatin Looseness That Allows Full-term Development at JoVE.com

We thank Satoshi Kishigami, Sayaka Wakayama, Hiroaki Nagatomo, Satoshi Kamimura, and Kana Kishida for providing critical comments and technical support. This work was partially funded by the Ministry of Education, Culture, Sports, Science and Technology program for promoting the reform of national universities to M.O.; the Japan Society for the Promotion of Science (16H02593), Asada Science Foundation, and the Takeda Science Foundation to T.W. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the University of Yamanashi. The protocol was approved by the Committee on the Ethics of Animal Experiments of the University of Yamanashi (Permit Number: A24-50). All surgeries were performed under tribromoethanol anesthesia, and all efforts were made to minimize suffering. An illustrated overview of the procedures and time-table are shown in Figure 1 and <strong...

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As revealed in this study, the zFRAP analysis does not cause critical damage to full-term development, suggesting this method is a very useful tool to reveal the association between molecular events and the embryonic developmental potential. During reprogramming, into the two-cell like state of ES cells, by which the differential potential of those cells becomes as high as that of two-cell stage embryos, chromatin looseness changes into that comparable with two-cell stage embryos5. Accordingly, it...

After fertilization, the chromatin structure is altered dynamically, and zygotic chromatin structure is then eventually established1,2. During this period, in paternal pronuclei, the dominant chromatin protein is changed from protamine into histone. The resulting chromatin is extremely different from that of sperms and female oocytes in several points (e.g., histone variant composition, histone modification). Thus, formed zygotic chromatin is thought to be important for subsequent embryonic development. However, despite efforts to reveal the details of zygotic chromatin structure over long periods, methods to evaluate the quality of zygotes or to predict their full-term development at the one-cell stage by analyzing their chromatin structure have never been established.
In the previous study, it is discovered that zygotes have an extremely loosened chromatin structure3. Currently, chromatin looseness or openness is believed to be an important factor for cellular differentiation potential in embryonic stem (ES) cells4. ES cells do not exhibit homogeneity in nature, but are rather heterogeneous; in ES cell colonies, some transiently acquire a higher differentiation potential comparable to blastomeres of two-cell stage embryos. During this transition into the two-cell like state, chromatin looseness in ES cells changes into what is comparable with two-cell stage embryos5. Thus, chromatin looseness seems to be important for cellular differentiation potential and it is possible that extensively open chromatin in zygotes is useful for the evaluation of zygotic developmental potential.
Live imaging is a powerful tool that allows for the analysis of molecular events during ontogenesis since this method allows for subsequent development and even full-term development6. As one of the live imaging methods, FRAP analysis has been used to examine chromatin looseness in preimplantation embryos and ES cells3,4,5. If zygotic chromatin looseness can be analyzed without a detrimental effect on full-term development by FRAP analysis, it may be a valuable tool for the evaluation of the quality of embryos at the one-cell stage. However, the effects on full-term development by this experimental method have not been examined. Recently, an experimental system using FRAP to evaluate zygotic chromatin looseness was developed. Because this was a new observation system for zygotes, it was termed as zygotic FRAP (zFRAP). zFRAP did not critically affect full-term development and has been reported elsewhere7. In this report, the protocol of this experimental method is described.

<table border="0" cellpadding="0" cellspacing="0" width="1022">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:260px;">Confocal laser scaning microscope</td>
			<td style="width:208px;">Olympus</td>
			<td style="width:119px;">FV1200</td>
			<td style="width:435px;">FV1000 can be also used for FRAP analysis (reference #7)</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Thermo plate</td>
			<td style="width:208px;">Tokai Hit</td>
			<td style="width:119px;">TP-110RH26</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Inverted microscope</td>
			<td style="width:208px;">Olympus</td>
			<td style="width:119px;">IX71</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Micro manupilator</td>
			<td style="width:208px;">Narishige</td>
			<td style="width:119px;">MMO-202ND</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Pieze Micro Micromanipulator</td>
			<td style="width:208px;">Prime tech</td>
			<td style="width:119px;">PMAS-CT150</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">35 mm culture dish</td>
			<td style="width:208px;">Falcom</td>
			<td style="width:119px;">351008</td>
			<td>35 x 100 mm style; for IVF</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">60 mm culture dish</td>
			<td style="width:208px;">Falcom</td>
			<td style="width:119px;">351007</td>
			<td>60 x 15 mm style; for embryo culture</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">50 mm culture dish</td>
			<td style="width:208px;">Falcom</td>
			<td style="width:119px;">351006</td>
			<td>50 x 9 mm style; for manipulation on the stage</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">50 mm glass bottom dish</td>
			<td style="width:208px;">Matsunami</td>
			<td style="width:119px;">D910400</td>
			<td>50 mm dish, 27 mm &#966; hole size; for FRAP analysis</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Mineral oil</td>
			<td style="width:208px;">Organic spceiality chemicals</td>
			<td style="width:119px;">625071</td>
			<td>For FRAP analysis on the glass bottom dishes</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Mineral oil</td>
			<td style="width:208px;">Sigma</td>
			<td style="width:119px;">M8410-1L</td>
			<td>For IVF and embryo culture</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">glass capillary</td>
			<td style="width:208px;">Drummond</td>
			<td style="width:119px;">1-000-1000</td>
			<td>For handling mouse zygotes</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Borosilicate glass</td>
			<td style="width:208px;">Prime tech</td>
			<td style="width:119px;">B100-75-10-PT</td>
			<td>For microinjection of mRNA</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:260px;">Micropipett puller</td>
			<td style="width:208px;">Sutter instrument</td>
			<td style="width:119px;">P-97/IVF</td>
			<td style="width:435px;">For preparation of the injection or holding neadle (out side diameter: 80 &#181;m, inner diameter: 10 &#181;m)&#160;</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Microforge</td>
			<td style="width:208px;">&#160;Narishige</td>
			<td>MF-900</td>
			<td></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:260px;">mMESSAGE MACHINE SP6 Transcription kit</td>
			<td style="width:208px;">Thermo 
			Fisher scientific</td>
			<td style="width:119px;">AM1340</td>
			<td></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:260px;">Poly (A) tailing kit</td>
			<td style="width:208px;">Thermo 
			Fisher scientific</td>
			<td style="width:119px;">AM1350</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">PVP solution 10% (PVP-HTF)</td>
			<td style="width:208px;">IrvineSceientific</td>
			<td style="width:119px;">99311</td>
			<td>HEPES buffered HTF containing 10% PVP</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Sodium HEPES</td>
			<td style="width:208px;">Sigma</td>
			<td style="width:119px;">H3784</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">pTOPO eGFP-H2B</td>
			<td style="width:208px;"></td>
			<td style="width:119px;"></td>
			<td>Template plasmid for eGFP-H2B mRNA (reference #6)</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:260px;">NorthernMax Gly Sample loading Dye&#160;</td>
			<td style="width:208px;">Thermo 
			Fisher scientific</td>
			<td style="width:119px;">AM8551</td>
			<td>For electrophoresis of in vitro transcribed mRNA</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Phenol chloroform isamyl alcohol</td>
			<td style="width:208px;">nacalai tesque</td>
			<td style="width:119px;">25970-14</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Chloroform</td>
			<td style="width:208px;">nacalai tesque</td>
			<td style="width:119px;">&#160;08401-65</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Not I</td>
			<td style="width:208px;">TOYOBO</td>
			<td style="width:119px;">NOT-111X</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">Ethachinmate</td>
			<td style="width:208px;">WAKO</td>
			<td style="width:119px;">318-01793</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:260px;">3664 Otical power meter</td>
			<td style="width:208px;">Hioki</td>
			<td style="width:119px;">3664</td>
			<td>&#160;Power meter for laser power</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:260px;">Stereomicmicroscope</td>
			<td style="width:208px;">Olympus</td>
			<td style="width:119px;">SZX16</td>
			<td></td>
		</tr>
	</tbody>
</table>

zygotic fluorescence recovery after photo-bleaching analysis for chromatin looseness that allows full-term development

Live imaging is a powerful tool that allows for the analysis of molecular events during ontogenesis. Recently, chromatin looseness or openness has been shown to be involved in the cellular differentiation potential of pluripotent embryonic stem cells. It was previously reported that compared with embryonic stem cells, zygotes harbor an extremely loosened chromatin structure, suggesting its association with their totipotency. However, until now, it has not been addressed whether this extremely loosened/open chromatin structure is important for embryonic developmental potential. In the present study, to examine this hypothesis, an experimental system in which zygotes that were analyzed by fluorescence recovery after photo-bleaching can develop to term without any significant damage was developed. Importantly, this experimental system needs only a thermos-plate heater in addition to a confocal laser scanning microscope. The findings of this study suggest that fluorescence recovery after photo-bleaching analysis (FRAP) analysis can be used to investigate whether the molecular events in zygotic chromatin are important for full-term development.

zFRAP analysis with eGFP-H2B
Properly produced mRNA encoding eGFP-H2B, which is seen as a shifted band caused by poly A tailing (Figure 2A), was injected into the cytoplasm of zygotes with a 2nd polar body at 1 - 3 h after insemination (Figure 2B). Eight to 12 h after insemination, zygotes with 2 pronuclei showing the expression of eGFP-H2B were collected and subjected to ...

Watch this Scientific Journal Video about Zygotic Fluorescence Recovery After Photo-bleaching Analysis for Chromatin Looseness That Allows Full-term Development at JoVE.com

Zygotic Fluorescence Recovery After Photo-bleaching Analysis for Chromatin Looseness That Allows Full-term Development

Chromatin looseness appears to be involved in the developmental potential of blastomeres. However, it is not known whether chromatin looseness can be used as a reliable index for the developmental potential for embryos. Here, an experimental system in which chromatin looseness-evaluated zygotes can develop to full term has been described.

Live imaging is a powerful tool that allows for the analysis of molecular events during ontogenesis. Recently, chromatin looseness or openness has been ...

The overall goal of this zygotic FRAP or zFRAP is to examine the association between zygotic chromatin looseness and embryonic development potential to term. This method can help answer key questions in the developmental biology field, such as embryonic development. The main advantage of this technique is that it allows the analyzed zygote to develop to full term without significant damage.Visual demonstration of this method is critical as the zFRAP analysis steps are difficult to learn because the experimental condition setting and operation for this analysis are very complex. After preparing eGFP-H2B RNA according to the text protocol, use nuclease-free water to dilute it to 250 nanograms per microliter. In a 60-millimeter dish, place two to three drops each of PVP-HTF, five to six drops of Hepes-buffered CZB, and eGFP-H2B mRNA.Then, use mineral oil to cover the drops. Using a pipette puller, pull borosilicate glass. After breaking the tip, use a microforge to bend the glass pipette to around 30 degrees.Prior to microinjection, confirm that the plate heater on the stage of the micromanipulator is off to prevent killing the zygotes during mRNA injection. Then, using 10%PVP-HTF, wash and coat the inside of the injection needles. Next from the tips fill the glass capillaries with the diluted eGFP-H2B mRNA.Collect the fertilized zygotes with a second polar body, and transfer 20 to 25 of them on to the chamber of the microscope stage. Then, with a holding pipette, hold the zygote and break the zona pellucida and the cytosolic membrane with a piezo drive. Inject about 10 picoliters of mRNA into the cytoplasm of each zygote.Complete the injections within 10 minutes to prevent damage caused by culturing the zygotes outside of the incubator. 10 minutes after microinjection, wash the zygotes in at least three drops of CZB and culture them at 38 degrees Celsius until FRAP analysis. One hour prior to zFRAP analysis, turn on the laser and hot plate attached to the stage of the confocal microscope.Set the temperature to 38 degrees Celsius. On a 60-millimeter glass-bottomed dish, pipette six to 10 microliters of Hepes-buffered CZB medium and cover it with mineral oil. Then, warm the dish on the heater until zygote collection.To make it easy to find the zygote with the confocal microscope, it is important to put the drops throughout the center of the dish. Eight to 12 hours after insemination, collect five to 10 eGFP-H2B expressing zygotes and transfer them to a six to 10-microliter drop of pre-warmed Hepes-buffered CZB medium. To perform a precise quantitative analysis it is important to put the zygote toward the center of the Hepes-buffered CZB drops.Set the bleaching and imaging conditions according to the manufacturer's instructions. For example, under Acquisition Setting, set the scanning speed to four microseconds per pixel and the size to five hundred and twelve. Increase the digital zoom to five, open the DyeList"and choose eGFP"Then, set the observation time to one point six seconds and the number of pictures to 12.Next, start the Stimulus Setting"panel and on UseScanner"click Main"Set the scanning speed to 10 microseconds per pixel. Click Activation in Series"Set PreActivation"to three frames and activation time to five seconds. Then, click Focus x2"and click Stop"Under the stimulus setting panel click Clip Rect"Set the ROI to 40 by 40 pixels.Click Time"and XY"Then, use an optical power meter to access the laser power. It is important to have the lights turned off when measuring the laser. After adjusting the laser gage to set the bleaching and imaging laser power, on the toolbar click Live"and then start Live Plot"Place the oil on the objective lens.Set the chamber on the stage and then find the zygotes in the drops. After finding zygotes, determine the ROI position by clicking Focus x2"And then in the Live Plot"window adjust the HV power gage for the eGFP"channel fluorescence intensity to around 2, 000. To start the zFRAP analysis, click XY"After FRAP analysis, click Series Done"Obtain the FRAP analyzed data, then click on Save As"to save the file 2D View image"as a preferred named file.Use Copy"ROI and Paste"ROI to prepare a reference region and to background respectively. Next, select ROI, REF, and BG, and then in the 2D View"image window, click Series Analysis"Obtain RoFRAP data and then in the Live Plot"window click the Save"button. Carry out data calculations according to the text protocol.Eight to 12 hours after insemination, zygotes with two pronucleai showing the expression of eGFP-H2B"were collected and subjected to zFRAP analysis. After bleaching, the intensity of the eGFP-H2B fluorescent signal recovered slightly because of the inflow of eGFP-H2B into the ROI from the unbleached area in the nucleoplasm. Recovery curves reveal that male pronucleai recovered more quickly and with more mobile fractions than female pronucleai.As demonstrated in these images and graph, after zFRAP analysis, washed and cultured zygotes in CZB medium developed to the blastocyst stage without significant damage. To analyze the full term development, embryos at the two-cell stage were transferred into the ovoducts of pseudo-pregnant mothers. As reported in this table, the birth rate of zFRAP analyzed embryos was slightly, but significantly lower than that of intact embryos but was the same as that of the no zFRAP control.In addition, the pups derived from zFRAP analyzed zygotes seemed healthy and fully developed. While attempting this procedure, it's important to remember to wait for the other expansion. All budget objectorance to avoid focus drift.After watching this video, you should have a good understanding on how to analyze chromatin looseness in zygotes.

zygotic-fluorescence-recovery-after-photo-bleaching-analysis-for

Research

JoVE Journal

Developmental Biology

Measuring Protein Stability in Living Zebrafish Embryos Using Fluorescence Decay After Photoconversion (FDAP)

Protein stability influences many aspects of biology, and measuring the clearance kinetics of proteins can provide important insights into biological systems. In FDAP experiments, the clearance of proteins within living organisms can be measured. A protein of interest is tagged with a photoconvertible fluorescent protein, expressed in vivo and photoconverted, and the decrease in the photoconverted signal over time is monitored. The data is then fitted with an appropriate clearance model to determine the protein half-life. Importantly, the clearance kinetics of protein populations in different compartments of the organism can be examined separately by applying compartmental masks. This approach has been used to determine the intra- and extracellular half-lives of secreted signaling proteins during zebrafish development. Here, we describe a protocol for FDAP experiments in zebrafish embryos. It should be possible to use FDAP to determine the clearance kinetics of any taggable protein in any optically accessible organism.

Measuring Protein Stability in Living Zebrafish Embryos Using Fluorescence Decay After Photoconversion FDAP

Protein levels in cells and tissues are often tightly regulated by the balance of protein production and clearance. Using Fluorescence Decay After Photoconversion (FDAP), the clearance kinetics of proteins can be experimentally measured in vivo.

Protein stability influences many aspects of biology, and measuring the clearance kinetics of proteins can provide important insights into biological ...

Genome-wide Snapshot of Chromatin Regulators and States in Xenopus Embryos by ChIP-Seq

The recruitment of chromatin regulators and the assignment of chromatin states to specific genomic loci are pivotal to cell fate decisions and tissue and organ formation during development. Determining the locations and levels of such chromatin features in vivo will provide valuable information about the spatio-temporal regulation of genomic elements, and will support aspirations to mimic embryonic tissue development in vitro. The most commonly used method for genome-wide and high-resolution profiling is chromatin immunoprecipitation followed by next-generation sequencing (ChIP-Seq). This protocol outlines how yolk-rich embryos such as those of the frog Xenopus can be processed for ChIP-Seq experiments, and it offers simple command lines for post-sequencing analysis. Because of the high efficiency with which the protocol extracts nuclei from formaldehyde-fixed tissue, the method allows easy upscaling to obtain enough ChIP material for genome-wide profiling. Our protocol has been used successfully to map various DNA-binding proteins such as transcription factors, signaling mediators, components of the transcription machinery, chromatin modifiers and post-translational histone modifications, and for this to be done at various stages of embryogenesis. Lastly, this protocol should be widely applicable to other model and non-model organisms as more and more genome assemblies become available.

Genome-wide Snapshot of Chromatin Regulators and States in Xenopus Embryos by ChIP-Seq

The question of how chromatin regulators and chromatin states affect the genome in vivo is key to our understanding of how early cell fate decisions are made in the developing embryo. ChIP-Seq&#8212;the most popular approach to investigate chromatin features at a global level&#8212;is outlined here for Xenopus embryos.

The recruitment of chromatin regulators and the assignment of chromatin states to specific genomic loci are pivotal to cell fate decisions and tissue and ...

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 ...

Analysis of Cardiomyocyte Development using Immunofluorescence in Embryonic Mouse Heart

During heart development, the generation of myocardial-specific structural and functional units including sarcomeres, contractile myofibrils, intercalated discs, and costameres requires the coordinated assembly of multiple components in time and space. Disruption in assembly of these components leads to developmental heart defects. Immunofluorescent staining techniques are used commonly in cultured cardiomyocytes to probe myofibril maturation, but this ex vivo approach is limited by the extent to which myocytes will fully differentiate in culture, lack of normal in vivo mechanical inputs, and absence of endocardial cues. Application of immunofluorescence techniques to the study of developing mouse heart is desirable but more technically challenging, and methods often lack sufficient sensitivity and resolution to visualize sarcomeres in the early stages of heart development. Here, we describe a robust and reproducible method to co-immunostain multiple proteins or to co-visualize a fluorescent protein with immunofluorescent staining in the embryonic mouse heart and use this method to analyze developing myofibrils, intercalated discs, and costameres. This method can be further applied to assess cardiomyocyte structural changes caused by mutations that lead to developmental heart defects.

Mutations that lead to congenital heart defects benefit from in vivo investigation of cardiac structure during development, but high-resolution structural studies in the mouse embryonic heart are technically challenging. Here we present a robust immunofluorescence and image analysis method to assess cardiomyocyte-specific structures in the developing mouse heart.

During heart development, the generation of myocardial-specific structural and functional units including sarcomeres, contractile myofibrils, intercalated ...

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 ...

Isolation and Characterization of Mouse Antral Oocytes Based on Nucleolar Chromatin Organization

This protocol describes a simple and quick method to isolate and characterize mouse antral GV (Germinal Vesicle) oocytes as able (SN, Surrounded Nucleolus) or unable (NSN, Not Surrounded Nucleolus) to develop to the blastocyst stage after in vitro maturation (IVM) and in vitro fertilization (IVF). It makes use of Hoeschst33342 (or any other DNA intercalating dye) able to bind to the heterochromatin of the nucleolus showing a ring in the SN oocytes or not, like in the NSN oocytes. This represents the easiest and quickest way to sort both antral oocytes that can be eventually used for IVM or IVF procedures. 
Briefly, the protocol consists of the following steps: hormone injection to stimulate follicular growth; isolation of the oocytes at the GV stage from the antral compartment by puncturing the ovary with a sterile needle; preparation of thin glass pipettes for mouth pipetting of the oocytes; sorting of the oocytes with Hoechst33342 prepared at a supravital concentration; IVM, IVF or any other molecular/cellular analysis.
Unfortunately there are still few evidences to sort SN and NSN oocytes using less invasive techniques. If and once they will be identified, they could be potentially applied to human assisted reproductive technologies, although with several aspects that should be modified. To date, this technique has potential implications to dramatically increase IVM and IVF successful procedures in both endangered and species with economic interest.

Here we present a protocol for the characterization of mouse antral oocytes based on nucleolar organization.

This protocol describes a simple and quick method to isolate and characterize mouse antral GV (Germinal Vesicle) oocytes as able (SN, Surrounded ...

Analysis of Zebrafish Kidney Development with Time-lapse Imaging Using a Dissecting Microscope Equipped for Optical Sectioning

In order to understand organogenesis, the spatial and temporal alterations that occur during development of tissues need to be recorded. The method described here allows time-lapse analysis of normal and impaired kidney development in zebrafish embryos by using a fluorescence dissecting microscope equipped for structured illumination and z-stack acquisition. To visualize nephrogenesis, transgenic zebrafish (Tg(wt1b:GFP)) with fluorescently labeled kidney structures were used. Renal defects were triggered by injection of an antisense morpholino oligonucleotide against the Wilms tumor gene wt1a, a factor known to be crucial for kidney development.
The advantage of the experimental setup is the combination of a zoom microscope with simple strategies for re-adjusting movements in x, y or z direction without additional equipment. To circumvent focal drift that is induced by temperature variations and mechanical vibrations, an autofocus strategy was applied instead of utilizing a usually required environmental chamber. In order to re-adjust the positional changes due to a xy-drift, imaging chambers with imprinted relocation grids were employed.
In comparison to more complex setups for time-lapse recording with optical sectioning such as confocal laser scanning&#160;or light sheet microscopes, a zoom microscope is easy to handle. Besides, it offers dissecting microscope-specific benefits such as high depth of field and an extended working distance.
The method to study organogenesis presented here can also be used with fluorescence stereo microscopes not capable of optical sectioning. Although limited for high-throughput, this technique offers an alternative to more complex equipment that is normally used for time-lapse recording of developing tissues and organ dynamics.

The method described here allows time-lapse analysis of organ development in zebrafish embryos by using a fluorescence dissecting microscope capable of performing optical sectioning and simple strategies of readjustment to correct focal and planar drift.

In order to understand organogenesis, the spatial and temporal alterations that occur during development of tissues need to be recorded. The method ...

Using Light Sheet Fluorescence Microscopy to Image Zebrafish Eye Development

Light sheet fluorescence microscopy (LSFM) is gaining more and more popularity as a method to image embryonic development. The main advantages of LSFM compared to confocal systems are its low phototoxicity, gentle mounting strategies, fast acquisition with high signal to noise ratio and the possibility of imaging samples from various angles (views) for long periods of time. Imaging from multiple views unleashes the full potential of LSFM, but at the same time it can create terabyte-sized datasets. Processing such datasets is the biggest challenge of using LSFM. In this protocol we outline some solutions to this problem. Until recently, LSFM was mostly performed in laboratories that had the expertise to build and operate their own light sheet microscopes. However, in the last three years several commercial implementations of LSFM became available, which are multipurpose and easy to use for any developmental biologist. This article is primarily directed to those researchers, who are not LSFM technology developers, but want to employ LSFM as a tool to answer specific developmental biology questions. 
Here, we use imaging of zebrafish eye development as an example to introduce the reader to LSFM technology and we demonstrate applications of LSFM across multiple spatial and temporal scales. This article describes a complete experimental protocol starting with the mounting of zebrafish embryos for LSFM. We then outline the options for imaging using the commercially available light sheet microscope. Importantly, we also explain a pipeline for subsequent registration and fusion of multiview datasets using an open source solution implemented as a Fiji plugin. While this protocol focuses on imaging the developing zebrafish eye and processing data from a particular imaging setup, most of the insights and troubleshooting suggestions presented here are of general use and the protocol can be adapted to a variety of light sheet microscopy experiments.

Light sheet fluorescence microscopy is an excellent tool for imaging embryonic development. It allows recording of long time-lapse movies of live embryos in near physiological conditions. We demonstrate its application for imaging zebrafish eye development across wide spatio-temporal scales and present a pipeline for fusion and deconvolution of multiview datasets.

Light sheet fluorescence microscopy (LSFM) is gaining more and more popularity as a method to image embryonic development. The main advantages of LSFM ...

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is the formation of fibroblastic foci, which is associated with the disease severity. Mesenchymal cells consisting of the fibroblastic foci are proposed to be derived from several cell sources, including originally resident intrapulmonary fibroblasts and circulating fibrocytes from bone marrow. Recently, mesenchymal cells that underwent epithelial-mesenchymal transition (EMT) have been also supposed to contribute to the pathogenesis of fibrosis. In addition, EMT can be induced by transforming growth factor &#946;, and EMT can be enhanced by pro-inflammatory cytokines like tumor necrosis factor &#945;. The gel contraction assay is an ideal in vitro model for the evaluation of contractility, which is one of the characteristic functions of fibroblasts and contributes to wound repair and fibrosis. Here, the development of a gel contraction assay is demonstrated for evaluating contractile ability of mesenchymal cells that underwent EMT.

Development of an In Vitro Assay to Evaluate Contractile Function of Mesenchymal Cells that Underwent Epithelial-Mesenchymal Transition

Here, we describe the development and application of a gel contraction assay for evaluating contractile function in mesenchymal cells that underwent epithelial-mesenchymal transition.

Fibrosis is often involved in the pathogenesis of various chronic progressive diseases such as interstitial pulmonary disease. Pathological hallmark is ...

Correlative Super-resolution and Electron Microscopy to Resolve Protein Localization in Zebrafish Retina

We present a method to investigate the subcellular protein localization in the larval zebrafish retina by combining super-resolution light microscopy and scanning electron microscopy. The sub-diffraction limit resolution capabilities of super-resolution light microscopes allow improving the accuracy of the correlated data. Briefly, 110 nanometer thick cryo-sections are transferred to a silicon wafer and, after immunofluorescence staining, are imaged by super-resolution light microscopy. Subsequently, the sections are preserved in methylcellulose and platinum shadowed prior to imaging in a scanning electron microscope (SEM). The images from these two microscopy modalities are easily merged using tissue landmarks with open source software. Here we describe the adapted method for the larval zebrafish retina. However, this method is also applicable to other types of tissues and organisms. We demonstrate that the complementary information obtained by this correlation is able to resolve the expression of mitochondrial proteins in relation with the membranes and cristae of mitochondria as well as to other compartments of the cell.

This protocol describes the necessary steps to obtain subcellular protein localization results on zebrafish retina by correlating super-resolution light microscopy and scanning electron microscopy images.

We present a method to investigate the subcellular protein localization in the larval zebrafish retina by combining super-resolution light microscopy and ...