Name: tracing gene expression through detection of &#946;-galactosidase activity in whole mouse embryos
Uploaded: 2018-06-26T14:00:00
Description: Watch this Scientific Journal Video about Tracing Gene Expression Through Detection of Î²-galactosidase Activity in Whole Mouse Embryos at JoVE.com

We would like to thank the Histopathological Service for their technical assistance at the Centro Nacional de Investigaciones Cardiovasculares (CNIC). We also thank Dr. Motoharu Seiki for kindly providing Mt4-mmpLacZ mice, and Dr. Alicia G. Arroyo for supporting our project and for her critical reading of the manuscript. We wish to thank Peter Bonney for proofreading this article. This work was supported by Universidad Europea de Madrid by means of a grant (# 2017UEM01) awarded to C.S.C.

All experimental procedures were approved by the Committee on the Ethics of Animal Experiments of the CNIC (Centro Nacional de Investigaciones Cardiovasculares) and the Comunidad Aut&#243;noma de Madrid to ensure minimal animal suffering.
1. Collection of Embryos from Pregnant Mice (from E8.5 to E12.5)
<ol>
	<li>Sacrifice pregnant mice by either cervical dislocation or CO2 inhalation. The day of the first observed vaginal plug was considered embryonic day 0.5 (E0.5).</li>
	<li>Lay...

The E. coli LacZ gene has been widely used as a reporter in studies of gene expression patterns because of its high sensitivity and ease of detection. The present protocol describes a classic method for detecting &#946;-gal expression based on an enzymatic reaction that is easy and quick to perform as well as inexpensive. This method can be also applied without major modifications in whole mount embryos, intact organs, cryostat tissue sections or cultured cells.
Accurate application o...

In order to describe specific gene expression patterns, the use of reporter genes as markers has been paramount from Drosophila to mammals. In experiments involving transgenic and knockout animals, the bacterial &#946;-galactosidase gene (LacZ) of Escherichia coli (E. coli) is one of the most widely used1,2,3,4. &#946;-galactosidase (&#946;-gal) catalyzes the hydrolysis of &#946;-galactosides (such as lactose) into its monosaccharides (glucose and galactose)5. Its most commonly used substrate is X-gal (5-bromo-4-chloro-3-indolyl-&#946;-D-galactopyranoside), a glycoside that is hydrolyzed by &#946;-galactosidase giving rise to 5-bromo-4-chloro-3-hydroxyindole and galactose. The first is oxidized into a dimer that, when used combined with potassium ferri-and ferro-cyanide, produces a characteristic insoluble, blue color precipitate (Figure 1)6.
The LacZ gene started to be used as a reporter gene over thirty years ago7,8. Usually, LacZ is inserted downstream of an endogenous promoter in the place of the open reading frame, so it can be used in bacterial and cell culture to visualize cells containing a particular insert, as well as in transgenic animals as a tracer of endogenous gene expression patterns during development9. In this regard, the visualization of &#946;-galactosidase activity has been extensively used in Drosophila to understand the developmental and cellular processes from single cells to whole tissues. Drosophila genetics favor the generation of stable lines in which a modified P-element construct containing the reporter gene LacZ is inserted at random locations in the genome. Thus, when placed under the influence of enhancer elements it may drive its expression in a tissue specific manner, which has allowed the systematic analysis of the expression patterns of many genes during the past two decades10. In addition, the use of transgenic mice to monitor LacZ gene expression also allows detection of gene recombination events by Cre-loxP mediated recombination, and localization of the mutant embryonic stem cell derivatives in chimeric analyses11, which facilitates the control of LacZ expression in specific tissues as well as temporally. Also, in whole embryos, detection of the &#946;-galactosidase activity may produce differential staining patterns at different intensities that can be conveniently observed across different developmental stages to analyze temporal changes in gene expression8,12.
In this article, we present a protocol to visualize gene expression through X-gal staining in the whole mount tissue at early developmental stages of mouse embryos. We present this histochemical method as a highly sensitive and inexpensive technique that favors accurate detection of the labeled cells either in whole mount specimens or at the cellular level after paraffin embedded tissues or embryos. The method allows for the direct visualization of staining in the mouse tissue with the minimum background when compared with other methods13.

<table>
	<tbody>
		<tr>
			<td>REAGENTS</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2-Propanol</td>
			<td>SIGMA-ALDRICH</td>
			<td>24137-1L-R</td>
			<td></td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>SCHARLAU</td>
			<td>50004/ LE3Q2014</td>
			<td></td>
		</tr>
		<tr>
			<td>Aqueous mounting medium</td>
			<td>VECTOR LABS</td>
			<td>H-5501</td>
			<td></td>
		</tr>
		<tr>
			<td>Synthetic mounting media</td>
			<td>MERCK</td>
			<td>100579</td>
			<td></td>
		</tr>
		<tr>
			<td>96% Ethanol</td>
			<td>PROLABO</td>
			<td>20824365</td>
			<td></td>
		</tr>
		<tr>
			<td>99.9% Ethanol absolute</td>
			<td>SCHARLAU</td>
			<td>ET00021000</td>
			<td></td>
		</tr>
		<tr>
			<td>50% Glutaraldehyde solution</td>
			<td>SIGMA-ALDRICH</td>
			<td>G6403-100ml</td>
			<td></td>
		</tr>
		<tr>
			<td>85% Glycerol</td>
			<td>MERCK</td>
			<td>104094</td>
			<td></td>
		</tr>
		<tr>
			<td>99.9% Glycerol</td>
			<td>SIGMA-ALDRICH</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride hexahydrate</td>
			<td>SIGMA-ALDRICH</td>
			<td>63064</td>
			<td></td>
		</tr>
		<tr>
			<td>Nonionic surfactant (Nonidet P-40)</td>
			<td>SIGMA-ALDRICH</td>
			<td>542334</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclear Fast Red counterstain</td>
			<td>SIGMA-ALDRICH</td>
			<td>N3020</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin pastilles</td>
			<td>MERCK</td>
			<td>111609</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>SIGMA-ALDRICH</td>
			<td>158127-500g</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (tablets)</td>
			<td>SIGMA-ALDRICH</td>
			<td>P4417-50TAB</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium ferrocyanate</td>
			<td>MERCK</td>
			<td>1049840500</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium ferrocyanide</td>
			<td>MERCK</td>
			<td>1049731000</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>SIGMA-ALDRICH</td>
			<td>S8032</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium deoxycholate</td>
			<td>SIGMA-ALDRICH</td>
			<td>30970</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium dihydrogen phosphate monohydrate</td>
			<td>SIGMA-ALDRICH</td>
			<td>106346</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium phosphate dibasic dihydrate</td>
			<td>SIGMA-ALDRICH</td>
			<td>71638</td>
			<td></td>
		</tr>
		<tr>
			<td>Thymol</td>
			<td>SIGMA-ALDRICH</td>
			<td>T0501</td>
			<td></td>
		</tr>
		<tr>
			<td>Tris hydrochloride (Tris HCl)</td>
			<td>SIGMA-ALDRICH</td>
			<td>10812846001 (Roche)</td>
			<td></td>
		</tr>
		<tr>
			<td>X-GAL</td>
			<td>VENN NOVA</td>
			<td>R-0004-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>VWR CHEMICALS</td>
			<td>VWRC28973.363</td>
			<td></td>
		</tr>
		<tr>
			<td>EQUIPMENT</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable plastic cryomolds 15x15x5 mm</td>
			<td>SAKURA</td>
			<td>4566</td>
			<td></td>
		</tr>
		<tr>
			<td>Rotatory Microtome</td>
			<td>Leica</td>
			<td>RM2235</td>
			<td></td>
		</tr>
		<tr>
			<td>Cassettes</td>
			<td>Oxford Trade</td>
			<td>OT-10-9046</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Cover Glasses 24x60 mm</td>
			<td>VWR</td>
			<td>ECN631-1575</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides</td>
			<td>Thermo Scientific, MENZEL-GL&#196;SER</td>
			<td>AGAA000001#12E</td>
			<td></td>
		</tr>
		<tr>
			<td>Adhesion microscope slides</td>
			<td>Thermo Scientific, MENZEL-GL&#196;SER</td>
			<td>J1820AMNZ</td>
			<td></td>
		</tr>
		<tr>
			<td>Flotation Water bath</td>
			<td>Leica</td>
			<td>HI1210</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable Low Profile Microtome Blades</td>
			<td>Feather</td>
			<td>UDM-R35</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin oven</td>
			<td>J.R. SELECTA</td>
			<td>2000205</td>
			<td></td>
		</tr>
		<tr>
			<td>Wax Paraffin dispenser</td>
			<td>J.R. SELECTA</td>
			<td>4000490</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereomicroscope</td>
			<td>Leica</td>
			<td>DM500</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene microcentrifuge tubes 2.0 mL</td>
			<td>SIGMA-ALDRICH</td>
			<td>T2795</td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene microcentrifuge tubes 1.5 mL</td>
			<td>SIGMA-ALDRICH</td>
			<td>T9661</td>
			<td></td>
		</tr>
		<tr>
			<td>Orbital shaker</td>
			<td>IKA Labortechnik</td>
			<td>HS250 BASIC</td>
			<td></td>
		</tr>
		<tr>
			<td>Stirring Hot Plate</td>
			<td>Bibby</td>
			<td>HB502</td>
			<td></td>
		</tr>
		<tr>
			<td>Vortex Shaker</td>
			<td>IKA Labortechnik</td>
			<td>MS1</td>
			<td></td>
		</tr>
		<tr>
			<td>Laboratory scale</td>
			<td>GRAM</td>
			<td>FH-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision scale</td>
			<td>Sartorius</td>
			<td>ISO9001</td>
			<td></td>
		</tr>
		<tr>
			<td>pHmeter</td>
			<td>Crison</td>
			<td>Basic 20</td>
			<td></td>
		</tr>
		<tr>
			<td>Optic fiber</td>
			<td>Optech</td>
			<td>PL2000</td>
			<td></td>
		</tr>
	</tbody>
</table>

tracing gene expression through detection of &#946;-galactosidase activity in whole mouse embryos

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. The classical histochemical reaction is based on the hydrolysis of the substrate X-gal in combination with ferric and ferrous ions, which produces an insoluble blue precipitate that is easy to visualize. Therefore, &#946;-galactosidase activity serves as a marker for the expression pattern of the gene of interest as the development proceeds. Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the subsequent method for paraffin sectioning and counterstaining. Additionally, a procedure for clarifying whole embryos is provided to better visualize X-gal staining in deeper regions of the embryo. Consistent results are obtained by performing this procedure, although optimization of reaction conditions is needed to minimize background activity. Limitations in the assay should be also considered, particularly regarding the size of the embryo in whole mount staining. Our protocol provides a sensitive and a reliable method for &#946;-galactosidase detection during the mouse development that can be further applied to the cryostat sections as well as whole organs. Thus, the dynamic gene expression patterns throughout development can be easily analyzed by using this protocol in whole embryos, but also detailed expression at the cellular level can be assessed after paraffin sectioning.

Here we show the results from applying the standard protocol for the &#946;-galactosidase histochemical reaction using X-gal as the substrate in whole mouse embryos (Figure 1 and Figure 2). By using this protocol, we examine Membrane type 4-matrix metalloproteinase (Mt4-mmp) expression at different embryonic developmental stages (E9.5, E11.5, and E12.5) using Mt4-mmp mutant mice that express the LacZ reporter under the control of...

Watch this Scientific Journal Video about Tracing Gene Expression Through Detection of Î²-galactosidase Activity in Whole Mouse Embryos at JoVE.com

Tracing Gene Expression Through Detection of &amp;#946;-galactosidase Activity in Whole Mouse Embryos

Here we describe the standard protocol for the detection of &#946;-galactosidase activity in early whole mouse embryos and the method for paraffin sectioning and counterstaining. This is an easy and quick procedure to monitor gene expression during development that can also be applied to tissue sections, organs or cultured cells.

Tracing Gene Expression Through Detection of &#946;-galactosidase Activity in Whole Mouse Embryos

The Escherichia coli LacZ gene, encoding &#946;-galactosidase, is largely used as a reporter for gene expression and as a tracer in cell lineage studies. ...

This method can have answer key questions in the developmental biology field such as the study of gene expression patterns during embryonic development.The main advantages of this technique are that it is highly sensitive, easy and quick to perform and allows direct visualization of the staining in the whole mount tissue or at higher resolution after paraffin sectioning of the sample.Demonstrating the procedure will be Dr Maria Jose Blanco, Dr Anabel Learte, Dr Emma Munoz and Dr Miguel Marchena.All of them are senior post-doc from my lab.Begin by incubating glutaraldehyde-fixed transgenic embryos expressing galactosidase in freshly prepared X-gal rinse buffer for 10 minutes at room temperature.Use wild type litter-made embryos as negative controls for the enzymatic reaction.Next, replace the rinse buffer with X-gal staining solution at pH 8-9.Protect from light and incubate for 2 hours to overnight at 37

tracing-gene-expression-through-detection-galactosidase-activity

Research

JoVE Journal

Developmental Biology

Quantitative Analysis of Protein Expression to Study Lineage Specification in Mouse Preimplantation Embryos

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for embryo collection, immunofluorescence, imaging on a confocal microscope, and image segmentation and analysis are described. This method allows quantitation of the expression of multiple nuclear markers and the spatial (XYZ) coordinates of all cells in the embryo. It takes advantage of MINS, an image segmentation software tool specifically developed for the analysis of confocal images of preimplantation embryos and embryonic stem cell (ESC) colonies. MINS carries out unsupervised nuclear segmentation across the X, Y and Z dimensions, and produces information on cell position in three-dimensional space, as well as nuclear fluorescence levels for all channels with minimal user input. While this protocol has been optimized for the analysis of images of preimplantation stage mouse embryos, it can easily be adapted to the analysis of any other samples exhibiting a good signal-to-noise ratio and where high nuclear density poses a hurdle to image segmentation (e.g., expression analysis of embryonic stem cell (ESC) colonies, differentiating cells in culture, embryos of other species or stages, etc.).

This protocol presents a method to perform quantitative, single-cell in situ analysis of protein expression to study lineage specification in mouse preimplantation embryos. The procedures necessary for collection of blastocysts, whole-mount immunofluorescent detection of proteins, imaging of samples on a confocal microscope, and nuclear segmentation and image analysis are described.

This protocol presents a method to perform quantitative, single-cell in situ analyses of protein expression to study lineage specification in mouse ...

Multi-target Chromogenic Whole-mount In Situ Hybridization for Comparing Gene Expression Domains in Drosophila Embryos

To analyze gene regulatory networks active during embryonic development and organogenesis it is essential to precisely define how the different genes are expressed in spatial relation to each other in situ. Multi-target chromogenic whole-mount in situ hybridization (MC-WISH) greatly facilitates the instant comparison of gene expression patterns, as it allows distinctive visualization of different mRNA species in contrasting colors in the same sample specimen. This provides the possibility to relate gene expression domains topographically to each other with high accuracy and to define unique and overlapping expression sites. In the presented protocol, we describe a MC-WISH procedure for comparing mRNA expression patterns of different genes in Drosophila embryos. Up to three RNA probes, each specific for another gene and labeled by a different hapten, are simultaneously hybridized to the embryo samples and subsequently detected by alkaline phosphatase-based colorimetric immunohistochemistry. The described procedure is detailed here for Drosophila, but works equally well with zebrafish embryos.

Multi-target Chromogenic Whole-mount In Situ Hybridization for Comparing Gene Expression Domains in Drosophila Embryos

We describe a multi-target chromogenic whole-mount in situ hybridization (MC-WISH) procedure in intact Drosophila embryos allowing simultaneous and specific detection of three different mRNA distribution patterns by contrasting color precipitates.

To analyze gene regulatory networks active during embryonic development and organogenesis it is essential to precisely define how the different genes are ...

In Vivo Imaging of Transgenic Gene Expression in Individual Retinal Progenitors in Chimeric Zebrafish Embryos to Study Cell Nonautonomous Influences

The genetic and technical strengths have made the zebrafish vertebrate a key model organism in which the consequences of gene manipulations can be traced in vivo throughout the rapid developmental period. Multiple processes can be studied including cell proliferation, gene expression, cell migration and morphogenesis. Importantly, the generation of chimeras through transplantations can be easily performed, allowing mosaic labeling and tracking of individual cells under the influence of the host environment. For example, by combining functional gene manipulations of the host embryo (e.g., through morpholino microinjection) and live imaging, the effects of extrinsic, cell nonautonomous signals (provided by the genetically modified environment) on individual transplanted donor cells can be assessed. Here we demonstrate how this approach is used to compare the onset of fluorescent transgene expression as a proxy for the timing of cell fate determination in different genetic host environments.
In this article, we provide the protocol for microinjecting zebrafish embryos to mark donor cells and to cause gene knockdown in host embryos, a description of the transplantation technique used to generate chimeric embryos, and the protocol for preparing and running in vivo time-lapse confocal imaging of multiple embryos. In particular, performing multiposition imaging is crucial when comparing timing of events such as the onset of gene expression. This requires data collection from multiple control and experimental embryos processed simultaneously. Such an approach can easily be extended for studies of extrinsic influences in any organ or tissue of choice accessible to live imaging, provided that transplantations can be targeted easily according to established embryonic fate maps.

In Vivo Imaging of Transgenic Gene Expression in Individual Retinal Progenitors in Chimeric Zebrafish Embryos to Study Cell Nonautonomous Influences

Live tracking of individual WT retinal progenitors in distinct genetic backgrounds allows for the assessment of the contribution of cell non-autonomous signaling during neurogenesis. Here, a combination of gene knockdown, chimera generation via embryo transplantation and in vivo time-lapse confocal imaging was utilized for this purpose.

The genetic and technical strengths have made the zebrafish vertebrate a key model organism in which the consequences of gene manipulations can be traced ...

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 ...

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 ...

Visualizing the Node and Notochordal Plate In Gastrulating Mouse Embryos Using Scanning Electron Microscopy and Whole Mount Immunofluorescence

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is the formation of the transient organizers, the node and notochordal plate, from cells that have passed through the primitive streak. The proper formation of these signaling centers is essential for the development of the body plan and techniques to visualize them are of high interest to mouse developmental biologists. The node and notochordal plate lie on the ventral surface of gastrulating mouse embryos around embryonic day (E) 7.5 of development. The node is a cup-shaped structure whose cells possess a single slender cilium each. The proper subcellular localization and rotation of the cilia in the node pit determines left-right asymmetry. The notochordal plate cells also possess single cilia albeit shorter than those of the node cells. The notochordal plate forms the notochord which acts as an important signaling organizer for somitogenesis and neural patterning. Because the cells of the node and notochordal plate are transiently present on the surface and possess cilia, they can be visualized using scanning electron microscopy (SEM). Among other techniques used to visualize these structures at the cellular level is whole mount immunofluorescence (WMIF) using the antibodies against the proteins that are highly expressed in the node and notochordal plate. In this report, we describe our optimized protocols to perform SEM and WMIF of the node and notochordal plate in developing mouse embryos to help in the assessment of tissue shape and cellular organization in wild-type and gastrulation mutant embryos.

The node and notochordal plate are transient signaling organizers in developing mouse embryos that can be visualized using several techniques. Here, we describe in detail how to perform two of the techniques to study their structure and morphogenesis: 1) scanning electron microscopy (SEM); and 2) whole mount immunofluorescence (WMIF).

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is ...

Fast and Efficient Expression of Multiple Proteins in Avian Embryos Using mRNA Electroporation

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. The high transfection efficiency permits at least 4 distinct mRNAs to be co-transfected with ~87% efficiency. Most of the electroporated mRNAs are degraded during the first 2 h post-electroporation, permitting time-sensitive experiments to be carried out in the developing embryo. Finally, we describe how to dynamically image live embryos electroporated with mRNAs that encode various subcellular targeted fluorescent proteins.

We report messenger RNA (mRNA) electroporation as a method that permits fast and efficient expression of multiple proteins in the quail embryo model system. This method can be used to fluorescently label cells and record their in vivo movements by time-lapse microscopy shortly after electroporation.

We report that mRNA electroporation permits fluorescent proteins to label cells in living quail embryos more quickly and broadly than DNA electroporation. ...

Clonal Genetic Tracing using the Confetti Mouse to Study Mineralized Tissues

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its longevity can be a powerful way to reveal mechanisms of tissue development and maintenance. One of the most important tools currently available to monitor cells in vivo is the Confetti mouse model. The Confetti model can be used to genetically label individual cells in living mice with various fluorescent proteins in a cell type-specific manner and monitor their fate, as well as the fate of their progeny over time, in a process called clonal genetic tracing or clonal lineage tracing. This model was generated almost a decade ago and has contributed to an improved understanding of many biological processes, particularly related to stem cell biology, development, and renewal of adult tissues. However, preserving the fluorescent signal until image collection and simultaneous capturing of various fluorescent signals is technically challenging, particularly for mineralized tissue. This publication describes a step-by-step protocol for using the Confetti model to analyze growth plate cartilage that can be applied to any mineralized or nonmineralized tissue.

This method describes the use of the R26R-Confetti (Confetti) mouse model to study mineralized tissues, covering all steps from the breeding strategy to the image acquirements. Included is a general protocol that can be applied to all soft tissues and a modified protocol that can be applied to mineralized tissues.

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its ...

Laser Capture Microdissection of Mouse Embryonic Cartilage and Bone for Gene Expression Analysis

Laser capture microdissection (LCM) is a powerful tool to isolate specific cell types or regions of interest from heterogeneous tissues. The cellular and molecular complexity of skeletal elements increases with development. Tissue heterogeneity, such as at the interface of cartilaginous and osseous elements with each other or with surrounding tissues, is one obstacle to the study of developing cartilage and bone. Our protocol provides a rapid method of tissue processing and isolation of cartilage and bone that yields high quality RNA for gene expression analysis. Fresh frozen tissues of mouse embryos are sectioned and brief cresyl violet staining is used to visualize cartilage and bone with colors distinct from surrounding tissues. Slides are then rapidly dehydrated, and cartilage and bone are isolated subsequently by LCM. The minimization of exposure to aqueous solutions during this process maintains RNA integrity. Mouse Meckel&rsquo;s cartilage and mandibular bone at E16.5 were successfully collected and gene expression analysis showed differential expression of marker genes for osteoblasts, osteocytes, osteoclasts, and chondrocytes. High quality RNA was also isolated from a range of tissues and embryonic ages. This protocol details sample preparation for LCM including cryoembedding, sectioning, staining and dehydrating fresh frozen tissues, and precise isolation of cartilage and bone by LCM resulting in high quality RNA for transcriptomic analysis.

This protocol describes laser capture microdissection for the isolation of cartilage and bone from fresh frozen sections of the mouse embryo. Cartilage and bone can be rapidly visualized by cresyl violet staining and collected precisely to yield high quality RNA for transcriptomic analysis.

Laser capture microdissection (LCM) is a powerful tool to isolate specific cell types or regions of interest from heterogeneous tissues. The cellular and ...

Whole Mount Immunohistochemistry in Zebrafish Embryos and Larvae

Immunohistochemistry is a widely used technique to explore protein expression and localization during both normal developmental and disease states. Although many immunohistochemistry protocols have been optimized for mammalian tissue and tissue sections, these protocols often require modification and optimization for non-mammalian model organisms. Zebrafish are increasingly used as a model system in basic, biomedical, and translational research to investigate the molecular, genetic, and cell biological mechanisms of developmental processes. Zebrafish offer many advantages as a model system but also require modified techniques for optimal protein detection. Here, we provide our protocol for whole-mount fluorescence immunohistochemistry in zebrafish embryos and larvae. This protocol additionally describes several different mounting strategies that can be employed and an overview of the advantages and disadvantages each strategy provides. We also describe modifications to this protocol to allow detection of chromogenic substrates in whole mount tissue and fluorescence detection in sectioned larval tissue. This protocol is broadly applicable to the study of many developmental stages and embryonic structures.

Here, we present a protocol for fluorescent antibody-mediated detection of proteins in whole preparations of zebrafish embryos and larvae.

Immunohistochemistry is a widely used technique to explore protein expression and localization during both normal developmental and disease states. ...