Name: accurate and phenol free dna sexing of day 30 porcine embryos by pcr
Uploaded: 2016-02-14T14:00:00
Description: Watch this Scientific Journal Video about Accurate and Phenol Free DNA Sexing of Day 30 Porcine Embryos by PCR at JoVE.com

The authors would like to acknowledge the cooperation and financial contributions of the following research funding agency: Alberta Livestock and Meat Agency Ltd., Pork CRC, Alberta Pork, Hypor A Hendrix Genetics Company and NSERC CRSNG.

In accordance with the Canadian Council on Animal Care guidelines and with approval of the Faculty Animal Policy and Welfare Committee - Livestock of the University of Alberta, pregnant sows were euthanized by trained staffs at approximately Day 30 of pregnancy and embryos were collected. Use examination gloves at all times during the procedures.
1. Sample Collection and Sample Storage
<ol>
	<li>Euthanize sow using captive bolt followed by exsanguination. Wear examination gloves to collect the reproductive tract...

<ol>
	<li>Seidel, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Economics+of+selecting+for+sex:+the+most+important+genetic+trait.">Economics of selecting for sex: the most important genetic trait.</a> Theriogenology. 59, 585-598 (2003).</li><li>Guti&#233;rrez-Ad&#225;n, A., 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+consequences+of+sexual+dimorphism+during+pre-implantation+embryonic+development.">Development consequences of sexual dimorphism during pre-implantation embryonic development.</a> Reprod. Domest. Anim. 41, 54-62 (2006).</li><li>Rosenfeld, C. S., Roberts, R. 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F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amplification+of+the+ZFY+and+ZFX+genes+for+sex+identification+in+humans,+cattle,+sheep+and+goats.">Amplification of the ZFY and ZFX genes for sex identification in humans, cattle, sheep and goats.</a> Biotechnology (N Y). 8, 1279-1281 (1990).</li><li>Oliver, 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=Restricted+feed+intake+in+lactating+primiparous+sows.+II.+Effects+on+subsequent+litter+sex+ratio+and+embryonic+gene+expression.">Restricted feed intake in lactating primiparous sows. II. Effects on subsequent litter sex ratio and embryonic gene expression.</a> Reprod Fertil. Dev. 23, 899-911 (2011).</li><li>Truett, G. E., Heeger, P., Mynatt, R. L., Truett, A. A., Walker, J. A., Warman, M. 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Most of the existing protocols related to porcine embryos DNA sex typing are only suitable for early stage pre-implantation stage15,16. We have successfully developed a protocol suitable for porcine embryo screening during late gestation. Based on studies with similar developmental stages of embryos from previous studies6,18, the present protocol is considered to be safer and low cost.
This protocol is also suitable for a large number of samples for sex typing using PCR b...

The domestic pig has become a fundamental research subject in development, genetics and nutrition in both human and livestock sectors. The potential of pigs as biomedical models for human research can be attributed to their physiological similarities. In livestock, the manipulation of sex ratio can enhance the effectiveness of selection and genetic improvement programs1. Sexing individual embryos is a fundamental tool used in many experimental investigations including but not limited to genotype, epigenetics and X inactivation of sexual dimorphism during early embryo development2.
Studies in mice suggest that maternal diet and other factors may result in gender imbalance3. In pigs, causes of sex ratio imbalance include paternal breed4, uterine capacity5, and the sow&#39;s metabolic condition6. Since the differences observed in embryos and litters can be influenced by sexual dimorphism, researchers should be aware of embryo sex and sex ratios before drawing conclusions regarding their research. The development of efficient tools and protocols for sexing pig embryos at Day 30 of development will be discussed here.
Various methods of sex typing have been developed for genetic studies in model organisms and livestock. Particularly in livestock, identifying male and female early embryos is a very common practice to enhance genetic selection for breeding programs. Early embryos karyotyping in pig using Giemsa7 or the intense fluorescence8,9 techniques have been used for sex typing. However, these methods are time consuming and not suitable for screening large numbers of embryos quickly and accurately.
The most effective sex typing method is DNA amplification using a heat stable DNA polymerase and a pair of primers. DNA sexing by PCR method is more specific, rapid and sensitive, only requiring a minute amount of cellular materials. The first PCR-based embryo sexing was performed on humans10, and later in mice11, cattle12, buffalo13 and sheep14 pre-implantation embryos. In the pig, the earliest DNA sex typing method was established for pre-implantation embryos via a single pair of Y-chromosome specific DNA primers15. However, the most common PCR primers for sex determination were selected from the Y-chromosome of male specific SRY gene16 and the non-sex discriminative region of a zinc-finger gene located at both X and Y chromosome17. Subsequently, these primers have been applied to determine the sex of Day 30 embryos in this study with improved specificity of the primers to detect only the X- chromosome of a zinc-finger gene.
Genomic DNA from porcine pre-implantation embryos can be extracted by exposing an intact blastocyst to buffer with proteinase K16 or by taking a biopsy of a few cells from the individual early cleavage embryos15 and using them for direct PCR. However, release of DNA from porcine blood, hair, tissues or a large conceptus over a few centimeters in size is not effectively done using the proteinase K method. DNA extraction methods for these materials have been established using either time consuming phenol/chloroform protocols6 or expensive column based kits18. In order to avoid the use of potentially toxic chemicals, there is a trend to develop inexpensive, easy and phenol-free DNA extraction methods. This type of protocol for the isolation of PCR-quality genomic DNA from mouse19 and zebrafish20 tissues has been established using hot sodium hydroxide and Tris (HotSHOT). This study provides a protocol to obtain DNA with modified HotSHOT and redesigned duplex primer pairs for PCR sex typing directly from cell lysates of Day 30 porcine embryos with high accuracy.

<table border="0" cellpadding="0" cellspacing="0" width="1184">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">KAPA HiFi HotStart Ready Mix PCR kit&#160;</td>
			<td style="width:203px;">KAPABiosystems</td>
			<td style="width:189px;">KR0370</td>
			<td style="width:463px;">other Hot Start Taq polymerase can be used after optimization</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">SYBR Safe DNA Gel Stain</td>
			<td style="width:203px;">Life Technologies</td>
			<td style="width:189px;">S33102</td>
			<td>Ethidium bromide can be substituted for SYBR Safe</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Pig female and male genomic DNA</td>
			<td style="width:203px;">Zyagen</td>
			<td style="width:189px;">GP-160-F1 &#38; GP-160-M5</td>
			<td>Postive controls from the tissues of known sex DNA can be used.</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Typhoon FLA 9500 laser scanner</td>
			<td style="width:203px;">GE Healthcare Life Sciences</td>
			<td style="width:189px;">28-9969-43</td>
			<td>other imaging system can be used</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Free Soft Nitrile Examination Gloves</td>
			<td style="width:203px;">WWR</td>
			<td>89038-270</td>
			<td>any other examination glove can be used</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Sodium hydroxide, solid&#160;</td>
			<td style="width:203px;">Fisher</td>
			<td style="width:189px;">BP 359 -212</td>
			<td>Molecular Biology Grade</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Eppendorff DNA LoBind Tubes, 1.5 ml, PCR clean</td>
			<td style="width:203px;">Eppendorff</td>
			<td style="width:189px;">0030 108.051</td>
			<td>heat resistant</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">ThermoStat plus</td>
			<td style="width:203px;">Eppendorff</td>
			<td style="width:189px;">22670204</td>
			<td>Use as a incubator for 95C, don&#39;t need to use the heater</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Toothpick</td>
			<td>Bunzl Plc</td>
			<td style="width:189px;">75200815</td>
			<td style="width:463px;">Any round wooden toothpicks can be used - quality wood</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;width:331px;">Microcentrifuge 5417R/5417C</td>
			<td style="width:203px;">Eppendorff</td>
			<td style="width:189px;">22621807</td>
			<td>This model was discontinued. But another newer model can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:331px;">Microspatula</td>
			<td style="width:203px;">Fisher</td>
			<td style="width:189px;">SDI28540115</td>
			<td>Autoclaved before use each time.</td>
		</tr>
	</tbody>
</table>

accurate and phenol free dna sexing of day 30 porcine embryos by pcr

Research into prenatal programming in the pig has shown that the sex of the developing embryo or fetus can influence the developmental outcome. Therefore, the ability to determine an embryo&#39;s sex is necessary in many experiments particularly regarding early development. The present protocol demonstrates an inexpensive, rapid and non-toxic preparation of pig genomic DNA for use with PCR. Day 30 embryos must be humanely collected according to the guidelines established by Institutional Animal Policy and Welfare Committees for the present protocol. The preparation of the whole embryo for this PCR based sexing technique simply involves grinding the frozen embryo to a fine powder using a pre-chilled mortar and pestle. PCR-quality DNA is released from a small amount of embryo powder by applying a hot incubation in an alkaline lysis reagent. Next, the DNA solution is mixed with neutralization buffer and used directly for PCR. Two primer pairs are generated to detect specific sex determining region of the Y- chromosome (SRY) and ZFX region of the X- chromosome with high accuracy and specificity. The same protocol can be applied to other elongated embryos (Day 10 to Day 14) earlier than Day 30. Also, this protocol can be carried with 96-welled plates when screening a large number of embryos, making it feasible for automation and high-throughput sex typing.

A representative result of sex determination from 345 DNA lysates screening by PCR is shown in Figure 7 and summarized in Table 1.
As can be seen in Figure 7, the primers annealing temperature at 65 &#176;C is the optimal condition in this PCR protocol generating similar intensity and predicated amplicon sizes (Figure 5) among different samples.
<p class="jo...

Watch this Scientific Journal Video about Accurate and Phenol Free DNA Sexing of Day 30 Porcine Embryos by PCR at JoVE.com

Accurate and Phenol Free DNA Sexing of Day 30 Porcine Embryos by PCR

This protocol describes an accurate, inexpensive, rapid and non-toxic method to determine the sex of Day 30 porcine embryo using PCR method after grinding an embryo into powder without phenol chloroform extraction and DNA column purification.

Research into prenatal programming in the pig has shown that the sex of the developing embryo or fetus can influence the developmental outcome. Therefore, ...

The overall goal of this procedure is to accurately identify the sex of day 30 pig embryos, using phenol free DNA obtained from each embryo. And two pairs of sex-specific primers for a PCR reaction. This method has the potential to answer various questions related to reproductive physiology in livestock, such as the effect of maternal factors on sex ratio including uterine capacity and the metabolic state of the sow as well as various paternal factors.The advantage of this technique involves no toxic chemicals such as phenol-chloroform, or expensive columns during DNA purification. So, let's get the show on the road. Visual demonstration of this method is as important as symptom preparation.The steps are easy to learn but special care on the details is important, to avoid symptom cross contamination. Transfer embryo samples to a negative eighty degree celsius freezer, according to the text. Label sample tubes with the sample ID needed for the number of samples to be analyzed.Use dry ice to half fill a thermal container and insert a pre-labled sample tube into the dry ice. While wearing winter gloves, with a pair of examination gloves on top, transfer pre-chilled mortars and pestles from the negative eighty degrees celsius freezer to a dry ice container. Next, place a frozen embryo inside the mortar on the dry ice, then, pour adequate liquid nitrogen to cover the embryo.And use a pestle to grind it into a fine powder. Using a microspatula transfer the embryo powder to a pre-labled sample tube, and place the tube in the negative eighty degrees freezer. Repeat the grinding and freezing of each additional embryo, changing examination gloves in between samples to avoid cross contamination.After labelling all microcentrifuged tubes needed for the number of samples to be analyzed, transfer the sample tubes containing embryo powder from the negative eighty degrees celsius freezer to a container of dry ice. Pipette 180 microlitres of 50 millimolar sodium hydroxide into each pre-labled microcentrifuged tube. Preheat an incubator to ninety-five degrees celsius.With a toothpick, transfer approximately five to ten milligrams of embryo powder from a sample tube into a pre-labeled tube of sodium hydroxide. Slowly lift the toothpick from the solution to visualize the DNA lysate as a sticky white, transparent-like substance. Transfer the samples with DNA lysate to the ninety-five degrees celsius incubator for five minutes, then immediately transfer the tube to an insulated container filled with ice.Next, add twenty microlitres of one molar tris-hydrochloride directly into the tubes, and tap the tubes to gently mix. With pH paper, ensure that the pH is approximately 8.0. Then, centrifuge the tubes at two thousand G, and room tempurature for two minutes to remove undissolved tissue debris.Transfer 150 microlitres of the top clear supernatant into new tubes. Or, a 96 well plate. And store at four degrees celsius for up to two weeks.Or, negative twenty degrees celsius for up to one year. The success of this protocol is rely on how specific you design your primer on X and Y chromosome. So how do you make sure they are on X and Y chromosome?Using NCBI Map Viewer, is the best way to show that. To design sex-specific primers for PCR, use the NCBI website to obtain accession numbers for pore sign sex determining region Y.Or SRY and zinc finger protein X-linked, or ZFX. Copy and paste the accession numbers to an online primer design tool.Use nucleotide blast or blast N to validate the specificity of the primers against the current pore sign genomic database 104. To enter the sequences, are only located on the X and Y chromosome for SRY and ZFX, respectively. To carry out PCR with the DNA lysates, use any hot start ready mix PCR enzyme, and prepare a master mix by adding two sex-specific primers at a final concentration of 0.3 micromolar in a 15 microlitre PCR reaction.For the first time running the reactions prepare one PCR tube for the no template negative control, and two additional tubes for positive controls by adding one microlitre of commercially obtained sex pore sign genomic DNA. For subsequent rounds of PCR, include one microlitre of a sample from the last successful sexing analysis as a positive control. Set up the following PCR program in a thermocycler and carry out PCR.To varify the samples after PCR prepare a 2%TBE agarose gel with cyber DNA gel stain or ethidium bromide. Add 1.5 microlitres of 10X loading dye to the samples before loading onto the gel and running. Observe and adjust the band intensities under fluorescent light and capture an image of the gel.Identify embryos with one band as female and two bands as male. Shown here is a representative result for sex determination from 345 DNA lysates screened by PCR. The optimal primer's annealing temperature of 65 degrees celsius is sightly higher than the TM of the primers shown here for generating similar intensity and predicted ampilcon sizes.Two amplified products of SRY and ZFX are presented here. Lysate sample from female embryos produce only a single band of 506 based pairs DNA fragment from the ZFX gene located on the X chromosome. All male embryos produce two DNA fragments with equal intensity of 400 base pairs for SRY and 506 base pairs for ZFX.As shown here, DNA lysates did not show any PCR reaction inhibition after screening 345 embryos. Only three individuals were not sexed and the percentage of female embryos was slightly higher than males. Once this technique is mastered from grinding to carrying out PCR, it takes about one hour to process around ten embryos.When doing this technique, its important to avoid cross contamination, especially when transferring embryo powder to the tubes. Following this procedure, we can use other methods such as, DNA methylation, microarray, and sequencing to investigate genomic and epigenetic effects of nutrition and infectious disease between sexes. The development of this technique will pave the way for researchers in the areas of reproductive physiology and animal science to conduct research related to sexual dimorphism in various livestock species.After watching this video you should have a good understanding how to design sex specific primers, abstract DNA from embryos and perform PCR reaction using DNA lysates. Remember that working with dry ice is quite dangerous, so take proper precaution wear gloves and goggles.

accurate-and-phenol-free-dna-sexing-of-day-30-porcine-embryos-by-pcr

Research

JoVE Journal

Developmental Biology

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 ...

Application of the DNA-Specific Stain Methyl Green in the Fluorescent Labeling of Embryos

Methyl green has long been known as a histological stain with a specific affinity for DNA, although its fluorescent properties have remained unexplored until recently. In this article, we illustrate the method for preparing a methyl green aqueous stock solution, that when diluted can be used as a very convenient fluorescent nuclear label for fixed cells and tissues. Easy procedures to label whole zebrafish and chick embryos are detailed, and examples of images obtained shown. Methyl green is maximally excited by red light, at 633 nm, and emits with a relatively sharp spectrum that peaks at 677 nm. It is very inexpensive, non-toxic, highly stable in solution and very resistant to photobleaching when bound to DNA. Its red emission allows for unaltered high resolution scanning confocal imaging of nuclei in thick specimens. Finally, this methyl green staining protocol is compatible with other cell staining procedures, such as antibody labeling, or actin filaments labeling with fluorophore-conjugated phalloidin.

A method for fluorescent staining of fixed biological material with the specific DNA label methyl green is described. Methyl green is used in a diluted aqueous solution and is very resistant to photobleaching. Its far-red emission allows for deep specimen imaging, making it particularly adequate for whole embryos.

Methyl green has long been known as a histological stain with a specific affinity for DNA, although its fluorescent properties have remained unexplored ...

Methods for Precisely Localized Transfer of Cells or DNA into Early Postimplantation Mouse Embryos

Manipulation and culture of early mouse embryos is a powerful yet largely under-utilized technology enhancing the value of this model system. Conversely, cell culture has been widely used in developmental biology studies. However, it is important to determine whether in vitro cultured cells truly represent in vivo cell types. Grafting cells into embryos, followed by an assessment of their contribution during development is a useful method to determine the potential of in vitro cultured cells. In this study, we describe a method for grafting cells into a defined site of early postimplantation mouse embryos, followed by ex vivo culture. We also introduce an optimized electroporation method that uses glass capillaries of known diameter, allowing precise localization and adjustment of the number of cells receiving exogenous DNA with both high transfection efficiency and low cell death. These techniques, which do not require any specialized equipment, render experimental manipulations of the gastrulation and early organogenesis-stage mouse embryo possible, allowing analysis of commitment in cultured cell subpopulations and the effect of genetic manipulations in situ on cell differentiation.

We demonstrate a method for grafting cultured cells into defined sites of early mouse embryos to determine their in vivo potential. We also introduce an optimized electroporation method that uses glass capillaries of known diameter, allowing the precise delivery of exogenous DNA into a few cells in the embryos.

Manipulation and culture of early mouse embryos is a powerful yet largely under-utilized technology enhancing the value of this model system. Conversely, ...

Generation of Parabiotic Zebrafish Embryos by Surgical Fusion of Developing Blastulae

Surgical parabiosis of two animals of different genetic backgrounds creates a unique scenario to study cell-intrinsic versus cell-extrinsic roles for candidate genes of interest, migratory behaviors of cells, and secreted signals in distinct genetic settings. Because parabiotic animals share a common circulation, any blood or blood-borne factor from one animal will be exchanged with its partner and vice versa. Thus, cells and molecular factors derived from one genetic background can be studied in the context of a second genetic background. Parabiosis of adult mice has been &#160;used extensively to research aging, cancer, diabetes, obesity, and brain development. More recently, parabiosis of zebrafish embryos has been used to study the developmental biology of hematopoiesis. In contrast to mice, the transparent nature of zebrafish embryos permits the direct visualization of cells in the parabiotic context, making it a uniquely powerful method for investigating fundamental cellular and molecular mechanisms. The utility of this technique, however, is limited by a steep learning curve for generating the parabiotic zebrafish embryos. This protocol provides a step-by-step method on how to surgically fuse the blastulae of two zebrafish embryos of different genetic backgrounds to investigate the role of candidate genes of interest. In addition, the parabiotic zebrafish embryos are tolerant to heat shock, making temporal control of gene expression possible. This method does not require a sophisticated set-up and has broad applications for studying cell migration, fate specification, and differentiation in vivo during embryonic development.

This protocol provides step-by-step instruction on how to generate parabiotic zebrafish embryos of different genetic backgrounds. When combined with the unparalleled imaging capabilities of the zebrafish embryo, this method provides a uniquely powerful means to investigate cell-autonomous versus non-cell-autonomous functions for candidate genes of interest.

Surgical parabiosis of two animals of different genetic backgrounds creates a unique scenario to study cell-intrinsic versus cell-extrinsic roles for ...

Integration Free Derivation of Human Induced Pluripotent Stem Cells Using Laminin 521 Matrix

Xeno-free and fully defined conditions are key parameters for robust and reproducible generation of homogenous human induced pluripotent stem (hiPS) cells. Maintenance of hiPS cells on feeder cells or undefined matrices are susceptible to batch variances, pathogenic contamination and risk of immunogenicity. Utilizing the defined recombinant human laminin 521 (LN-521) matrix in combination with xeno-free and defined media formulations reduces variability and allows for the consistent generation of hiPS cells. The Sendai virus (SeV) vector is a non-integrating RNA-based system, thus circumventing concerns associated with the potential disruptive effect on genome integrity integrating vectors can have. Furthermore, these vectors have demonstrated relatively high efficiency in the reprogramming of dermal fibroblasts. In addition, enzymatic single cell passaging of cells facilitates homogeneous maintenance of hiPS cells without substantial prior experience of stem cell culture. Here we describe a protocol that has been extensively tested and developed with a focus on reproducibility and ease of use, providing a robust and practical way to generate defined and xeno-free human hiPS cells from fibroblasts.

Robust derivation of human induced pluripotent stem (hiPS) cells was achieved by using non-integrating Sendai virus (SeV) vector mediated reprogramming of dermal fibroblasts. hiPS cell maintenance and clonal expansion was performed using xeno-free and chemically defined culture conditions with recombinant human laminin 521 (LN-521) matrix and Essential E8 (E8) Medium.

Xeno-free and fully defined conditions are key parameters for robust and reproducible generation of homogenous human induced pluripotent stem (hiPS) ...

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound (30/45MHZ) System

Congenital heart defects (CHDs) are the most common cause of childhood morbidity and early mortality. Prenatal detection&#160;of the underlying molecular mechanisms of CHDs is&#160;crucial for inventing new preventive and therapeutic strategies. Mutant mouse models are powerful tools to discover new&#160;mechanisms&#160;and environmental stress modifiers that drive cardiac development and their potential&#160;alteration in CHDs. However, efforts to establish the causality of these putative contributors have been limited to histological&#160;and molecular studies&#160;in non-survival animal experiments, in which&#160;monitoring the key physiological and hemodynamic parameters is&#160;often absent. Live imaging technology has become an essential tool to establish the&#160;etiology of CHDs. In particular,&#160;ultrasound imaging can be used prenatally without surgically exposing the fetuses,&#160;allowing maintaining&#160;their baseline physiology while monitoring the impact of environmental stress&#160;on the hemodynamic and structural aspects of cardiac chamber development. Herein, we use the High-Frequency Ultrasound (30/45)&#160;system to examine the cardiovascular system in fetal mice at E18.5 in utero at the baseline and in response to prenatal hypoxia exposure. We demonstrate the feasibility of the system to measure cardiac chamber size, morphology, ventricular function, fetal heart rate, and umbilical artery flow indices, and their alterations in fetal mice exposed to systemic chronic hypoxia in utero in real time.

Fetal Mouse Cardiovascular Imaging Using a High-frequency Ultrasound 30/45MHZ System

High-frequency ultrasound imaging of the fetal mouse has improved imaging resolution and can provide precise non-invasive characterization of cardiac development and structural defects. The protocol outlined herein is designed to perform real-time fetal mice echocardiography in vivo.

Congenital heart defects (CHDs) are the most common cause of childhood morbidity and early mortality. Prenatal detection&#160;of the underlying molecular ...

Microinjection of DNA into Eyebuds in Xenopus laevis Embryos and Imaging of GFP Expressing Optic Axonal Arbors in Intact, Living Xenopus Tadpoles

The primary visual projection of tadpoles of the aquatic frog Xenopus laevis serves as an excellent model system for studying mechanisms that regulate the development of neuronal connectivity. During establishment of the retino-tectal projection, optic axons extend from the eye and navigate through distinct regions of the brain to reach their target tissue, the optic tectum. Once optic axons enter the tectum, they elaborate terminal arbors that function to increase the number of synaptic connections they can make with target interneurons in the tectum. Here, we describe a method to express DNA encoding green fluorescent protein (GFP), and gain- and loss-of-function gene constructs, in optic neurons (retinal ganglion cells) in Xenopus embryos. We explain how to microinject a combined DNA/lipofection reagent into eyebuds of one day old embryos such that exogenous genes are expressed in single or small numbers of optic neurons. By tagging genes with GFP or co-injecting with a GFP plasmid, terminal axonal arbors of individual optic neurons with altered molecular signaling can be imaged directly in brains of intact, living Xenopus tadpoles several days later, and their morphology can be quantified. This protocol allows for determination of cell-autonomous molecular mechanisms that underlie the development of optic axon arborization in vivo.

Microinjection of DNA into Eyebuds in Xenopus laevis Embryos and Imaging of GFP Expressing Optic Axonal Arbors in Intact, Living Xenopus Tadpoles

This protocol aims to demonstrate how to microinject a DNA/DOTAP mixture into eyebuds of one day old Xenopus laevis embryos, and how to image and reconstruct individual green fluorescent protein (GFP) expressing optic axonal arbors in tectal midbrains of intact, living Xenopus tadpoles.

The primary visual projection of tadpoles of the aquatic frog Xenopus laevis serves as an excellent model system for studying mechanisms that regulate the ...

In Situ Detection of Ribonucleoprotein Complex Assembly in the C. elegans Germline using Proximity Ligation Assay

Understanding when and where protein-protein interactions (PPIs) occur is critical to understanding protein function in the cell and how broader processes such as development are affected. The Caenorhabditis elegans germline is a great model system for studying PPIs that are related to the regulation of stem cells, meiosis, and development. There are a variety of well-developed techniques that allow proteins of interest to be tagged for recognition by standard antibodies, making this system advantageous for proximity ligation assay (PLA) reactions. As a result, the PLA is able to show where PPIs occur in a spatial and temporal manner in germlines more effectively than alternative approaches. Described here is a protocol for the application and quantification of this technology to probe PPIs in the C. elegans germline.

In Situ Detection of Ribonucleoprotein Complex Assembly in the C. elegans Germline using Proximity Ligation Assay

This protocol demonstrates use of the proximity ligation assay to probe for protein-protein interactions in situ in the C. elegans germline.

Understanding when and where protein-protein interactions (PPIs) occur is critical to understanding protein function in the cell and how broader processes ...

Accurate Follicle Enumeration in Adult Mouse Ovaries

Sexually reproducing female mammals are born with their entire lifetime supply of oocytes. Immature, quiescent oocytes are found within primordial follicles, the storage unit of the female germline. They are non-renewable, thus their number at birth and subsequent rate of loss largely dictates the female fertile lifespan. Accurate quantification of primordial follicle numbers in women and animals is essential for determining the impact of medicines and toxicants on the ovarian reserve. It is also necessary for evaluating the need for, and success of, existing and emerging fertility preservation techniques. Currently, no methods exist to accurately measure the number of primordial follicles comprising the ovarian reserve in women. Furthermore, obtaining ovarian tissue from large animals or endangered species for experimentation is often not feasible. Thus, mice have become an essential model for such studies, and the ability to evaluate primordial follicle numbers in whole mouse ovaries is a critical tool. However, reports of absolute follicle numbers in mouse ovaries in the literature are highly variable, making it difficult to compare and/or replicate data. This is due to a number of factors including strain, age, treatment groups, as well as technical differences in the methods of counting employed. In this article, we provide a step-by-step instructional guide for preparing histological sections and counting primordial follicles in mouse ovaries using two different methods: [1] stereology, which relies on the fractionator/optical dissector technique; and [2] the direct count technique. Some of the key advantages and drawbacks of each method will be highlighted so that reproducibility can be improved in the field and to enable researchers to select the most appropriate method for their studies.

Here, we describe, compare, and contrast two different techniques for accurate follicle counting of fixed mouse ovarian tissues.

Sexually reproducing female mammals are born with their entire lifetime supply of oocytes. Immature, quiescent oocytes are found within primordial ...

Cell Dissociation from the Tongue Epithelium and Mesenchyme/Connective Tissue of Embryonic-Day 12.5 and 8-Week-Old Mice

Cell dissociation has been an essential procedure for studies at the individual-cell level and/or at a cell-population level (e.g.,&#160;single cell RNA sequencing and primary cell culture). Yielding viable, healthy cells in large quantities is critical, and the optimal conditions to do so are tissue dependent. Cell populations in the tongue epithelium and underlying mesenchyme/connective tissue are heterogeneous and tissue structures vary in different regions and at different developmental stages. We have tested protocols for isolating cells from the mouse tongue epithelium and mesenchyme/connective tissue in the early developmental [embryonic day 12.5 (E12.5)] and young adult (8-week) stages. A clean separation between the epithelium and underlying mesenchyme/connective tissue was easy to accomplish. However, to further process and isolate cells, yielding viable healthy cells in large quantities, and careful selection of enzymatic digestion buffer, incubation time, and centrifugation speed and time are critical. Incubation of separated epithelium or underlying mesenchyme/connective tissue in 0.25% Trypsin-EDTA for 30 min at 37 &#176;C, followed by centrifugation at 200 x g for 8 min resulted in a high yield of cells at a high viability rate (&#62;90%) regardless of the mouse stages and tongue regions. Moreover, we found that both dissociated epithelial and mesenchymal/connective tissue cells from embryonic and adult tongues could survive in the cell culture-based medium for at least 3 h without a significant decrease of cell viability. The protocols will be useful for studies that require the preparation of isolated cells from mouse tongues at early developmental (E12.5) and young adult (8-week) stages requiring cell dissociation from different tissue compartments.

We have developed a generalized protocol to dissociate a large quantity of high-quality single cells from the epithelium and mesenchyme/connective tissue of embryonic and adult mouse tongues.

Cell dissociation has been an essential procedure for studies at the individual-cell level and/or at a cell-population level (e.g.,&#160;single cell RNA ...