著者は、原稿の重要な読書のためにヒューストンの研究室のメンバーに感謝したいと思います。研究は、DWHに与え国立衛生研究所（GM083999）によってサポートされています

<ol>
	<li>Brun, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oocyte+maturation+in+vitro:+contribution+of+the+oviduct+to+total+maturation+in+Xenopus+laevis.">Oocyte maturation in vitro: contribution of the oviduct to total maturation in Xenopus laevis.</a> Experientia. 31, 1275-1276 (1975).</li><li>Elinson, R. P., Pasceri, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+UV-sensitive+targets+in+dorsoanterior+specification+of+frog+embryos.">Two UV-sensitive targets in dorsoanterior specification of frog embryos.</a> Development. 106, 511-518 (1989).</li><li>Heasman, J., Holwill, S., Wylie, C. C., C, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fertilization+of+cultured+Xenopus+oocytes+and+use+in+studies+of+maternally+inherited+molecules.">Fertilization of cultured Xenopus oocytes and use in studies of maternally inherited molecules.</a> Methods Cell Biol. 36, 213-230 (1991).</li><li>Holwill, S., Heasman, J., Crawley, C., Wylie, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axis+and+germ+line+deficiencies+caused+by+u.v+irradiation+of+Xenopus+oocytes+cultured+in+vitro.">Axis and germ line deficiencies caused by u.v irradiation of Xenopus oocytes cultured in vitro.</a> Development. 100, 735-743 (1987).</li><li>Houston, D. W., King, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+critical+role+for+Xdazl,+a+germ+plasm-localized+RNA,+in+the+differentiation+of+primordial+germ+cells+in+Xenopus.">A critical role for Xdazl, a germ plasm-localized RNA, in the differentiation of primordial germ cells in Xenopus.</a> Development. 127, 447-456 (2000).</li><li>Mir, A., Heasman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+the+mother+can+help:+studying+maternal+Wnt+signaling+by+anti-sense-mediated+depletion+of+maternal+mRNAs+and+the+host+transfer+technique.">How the mother can help: studying maternal Wnt signaling by anti-sense-mediated depletion of maternal mRNAs and the host transfer technique.</a> Methods Mol Biol. 469, 417-429 (2008).</li><li>Rugh, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Experimental Embryology: Techniques and procedures. , (1962).</li><li>Smith, L. D., Ecker, R. E., Subtelny, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+induction+of+physiological+maturation+in+Rana+pipiens+oocytes+removed+from+their+ovarian+follicles.">In vitro induction of physiological maturation in Rana pipiens oocytes removed from their ovarian follicles.</a> Dev Biol. 17, 627-643 (1968).</li><li>Smith, L. D., Xu, W., Varnold, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oogenesis+and+oocyte+isolation.">Oogenesis and oocyte isolation.</a> Methods Cell Biol. 36, 45-60 (1991).</li><li>Woolf, T. M., Jennings, C. G., Rebagliati, M., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+stability,+toxicity+and+effectiveness+of+unmodified+and+phosphorothioate+antisense+oligodeoxynucleotides+in+Xenopus+oocytes+and+embryos.">The stability, toxicity and effectiveness of unmodified and phosphorothioate antisense oligodeoxynucleotides in Xenopus oocytes and embryos.</a> Nucleic Acids Res. 18, 1763-1769 (1990).</li><li>Wylie, C., Kofron, M., Payne, C., Anderson, R., Hosobuchi, M., Joseph, E., Heasman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maternal+beta-catenin+establishes+a+'dorsal+signal'+in+early+Xenopus+embryos.">Maternal beta-catenin establishes a 'dorsal signal' in early Xenopus embryos.</a> Development. 122, 2987-2996 (1996).</li><li>Zhang, J., Houston, D. W., King, M. L., Payne, C., Wylie, C., Heasman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+maternal+VegT+in+establishing+the+primary+germ+layers+in+Xenopus+embryos.">The role of maternal VegT in establishing the primary germ layers in Xenopus embryos.</a> Cell. 94, 515-524 (1998).</li><li>Zuck, M. V., Wylie, C. C., Heasman, J., Richter, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maternal+mRNAs+in+Xenopus+embryos:+an+antisense+approach..">Maternal mRNAs in Xenopus embryos: an antisense approach..</a> A comparative methods approach to the study of oocytes and embryos. , 341-354 (1998).</li></ol>

動物実験は、アイオワIACUC委員会の大学が定めるガイドラインおよび規則に従って行った。

転送が成功するには、受精し、卵母細胞の&gt; 50％（図3）の正常な切断になります。一般的に転送卵母細胞の間に30〜60パーセントは、神経胚の段階を過ぎても存続します。我々は通常、表現型を視覚化するだけでなく、分析のいくつかのタイプ（その場で、RT - PCR）のための十分な胚が得られる実験群あたり75から150卵母細胞を、転送する。実質的により多くの卵母細胞を注入すると、大幅に...

ソリューションとレシピ： OCM（卵母細胞の培養液、ワイリーらから変更、1996。） <table border="0"><tbody><tr><td> 70パーセントリーボビッツのL - 15培地（L -グルタミンを含む） </td><td> （インビトロジェン11415〜064） </td></tr><tr><td> 0.4 mg / mlのウシ血清アルブミン（BSA、フラクションV） </td><td> （シグマA - 9418〜50グラム） </td></tr><tr><td> 1Xペニシリン - ストレプトマイシン</td><td> （シグマP - 0781） </td></tr><tr><td colspan="2"> 5N NaOHでpHを7.6から7.8に調整する</td></tr><tr><td colspan="2"> 18℃で新鮮毎週、ストアを行う</td></tr></tbody></table> 10X MMR（Marcの改変リンゲル液;。ズックら 、1998） <table border="0"><tbody><tr><td> 1MのNaCl </td></tr><tr><td> 20mMのKClを</td></tr><tr><td> 20mMのCaCl 2を </td></tr><tr><td> 10mMのMgCl 2 </td></tr><tr><td> 150mMのHEPES </td></tr><tr><td> pHが7.6から7.8に調整する</td></tr><tr><td> 4℃で</td></tr></tbody></table>麻酔液<table border="0"><tbody><tr><td>を1g / L 3 - アミノ安息香酸エチルエステル（MS222） </td><td> （シグマA - 5040） </td></tr><tr><td colspan="2"> 0.7グラム/ L重炭酸ナトリウム</td></tr><tr><td colspan="2"> Amquel処理水に溶かす</td></tr><tr><td colspan="2">毎週新鮮な確認</td></tr></tbody></table>プロゲステロンの株式<table border="0"><tbody><tr><td> 100％エタノール、10 mMのプロゲステロン（シグマP - 0130） </td></tr><tr><td> 500分の1株式/実用的なソリューションのための100％エタノールで1 mMに希釈する</td></tr><tr><td> -20℃で保存</td></tr></tbody></table>バイタル色素（ヒースマンら 、1991から改変） <table border="0"><tbody><tr><td>青：0.1％ナイルブルー</td><td> （アルドリッチ121479 - 5G）、 </td></tr><tr><td>赤：0.25％ニュートラルレッド</td><td> （シグマN - 6634）、 </td></tr><tr><td>ブラウン：1％ビスマルクブラウン</td><td> （シグマB - 2759）、 </td></tr><tr><td colspan="2">グリーン（80μlの青+80μlの茶色）、 </td></tr><tr><td colspan="2">モーブ（80μlの青+80μlの赤）。 </td></tr><tr><td colspan="2">第六色、オレンジ色は（赤、80μlの+80μlの茶色）、また使用されるが、茶色と区別することは困難ですできます。 </td></tr></tbody></table>ブルー、レッドとブラウンの株式は、50 mLチューブに、脱イオン水で作ら振盪しながら20分間インキュベートし、臨床遠心機でスピンされています。上清をマイクロチューブに小分けして-20℃で保存されています

fertilization of xenopus oocytes using the host transfer method

初期の開発を脊椎動物に母性遺伝の分子の寄与を研究することは、しばしば時間と母性効果変異動物を生成するために必要な費用によって妨げられている。さらに、例えば、 アフリカツメガエルやゼブラフィッシュなどの生物の遺伝子機能を過剰発現または抑制する手法の多くは、十分にそのようなWntシグナル伝達などの重要な母体のシグナル伝達経路を標的に失敗する。 アフリカツメガエルでは、培養卵母細胞での遺伝子機能を操作し、その後それらを肥やすことはある程度までこれらの問題を改善することができます。卵母細胞は、手動で、ドナーの卵巣の組織からdefolliculated必要に応じて注射したり、文化の中で処理し、成熟を誘導するためにプロゲステロンによって刺激されています。それらはホストの卵管を通じて転と変更し、受精に必要なゼリーのコートを取得される、すると次に、卵母細胞は、排卵ホスト女性のカエルの体腔内に導入されています。結果として得られる胚は、その後、目的のステージに上げ、あらゆる実験的摂動の影響について分析することができる。このホストベースの転送方式は、初期の開発の基本的なメカニズムを暴くのに非常に有効であったと他の脊椎動物のモデル生物では利用できない実験的な幅広い可能性を可能にしました。

Watch this Scientific Journal Video about Fertilization of Xenopus oocytes using the Host Transfer Method at JoVE.com

Fertilization of Xenopus oocytes using the Host Transfer Method

施肥のための手順<em&gt;アフリカツメガエル卵母細胞</em&gt;ホストの転送方法によって。

の受精アフリカツメガエル卵母細胞ホストの転送方式を使用して

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to ...

fertilization-of-xenopus-oocytes-using-the-host-transfer-method

Research

JoVE Journal

Biology

Fertilization of Xenopus oocytes using the Host Transfer Method

14.5K ビュー.  University of Iowa. 施肥のための手順アフリカツメガエル卵母細胞ホストの転送方法によって。

ビデオ: Fertilization of Xenopus oocytes using the Host Transfer Method

Nuclear Transfer into Mouse Oocytes

Nuclear transfer into an unfertilized oocyte can restore developmental potential to a differentiated cell. This demonstrates that the processes underlying development, differentiation and aging are epigenetic rather than genetic processes. The reversibility of these processes opens exciting perspectives in basic research, and in the more distant future, in regenerative medicine. In the mouse, embryonic stem cells can be derived from cloned preimplantation stage embryos. Such embryonic stem cells have the ability to give rise to all cell types of the adult organism. Importantly, these cells are genetically identical to the donor. If applicable to human, this would allow the derivation of stem cells from a patient. These cells could then be differentiated into the affected cell type of the patient and studied in vitro, or used to replace the damaged or missing cells. The study of nuclear transfer in the mouse remains important as it can inform us about the principles of nuclear reprogramming. This movie and the accompanying protocol are intended to help learning nuclear transfer in the mouse, a method initially developed in the group of Prof. Yanagimachi (WAKAYAMA et al. 1998).

This movie and the protocol are intended to help learning nuclear transfer.

マウス卵母細胞への核移転

Nuclear transfer into an unfertilized oocyte can restore developmental potential to a differentiated cell. This demonstrates that the processes underlying ...

生物学

Retrieval of Mouse Oocytes

To date, only a few studies have reported successful manipulations of Peromyscus embryogenesis or reproductive biology.  Together with the Peromyscus Genetic Stock Center (http://stkctr.biol.sc.edu), we are characterizing the salient differences needed to develop this system.  A primary goal has been to optimize oocyte/early embryo retrieval.

This protocol illustrates the technique for extracting oocytes or early-stage fertilized embryos from the oviduct of mice. The ability to identify the infindibulum and insert a blunt end needle into it is essential to correctly performing the procedure.

マウス卵母細胞の検索

To date, only a few studies have reported successful manipulations of Peromyscus embryogenesis or reproductive biology.  Together with the Peromyscus ...

In Vitro Nuclear Assembly Using Fractionated Xenopus Egg Extracts

Nuclear membrane assembly is an essential step in the cell division cycle; this process can be replicated in the test tube by combining Xenopus sperm chromatin, cytosol, and light membrane fractions. Complete nuclei are formed, including nuclear membranes with pore complexes, and these reconstituted nuclei are capable of normal nuclear processes.

Nuclear membrane assembly is an essential step in the cell division cycle; this process can be replicated in the test tube by combining Xenopus sperm chromatin, cytosol, and light membrane fractions. Complete nuclei are formed, including nuclear membranes with pore complexes, and these reconstituted nuclei are capable of normal nuclear processes.

分別アフリカツメガエルの卵抽出を用いたin vitro核アセンブリで

Nuclear membrane assembly is an essential step in the cell division cycle; this process can be replicated in the test tube by combining Xenopus sperm ...

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological measurement of single or multiple ion channels in cells. This technique can be applied to ion channels in both their native environment and expressed in heterologous cells, such as oocytes harvested from the African clawed frog, Xenopus laevis. Here, we describe the well-established technique of patch clamp recording from Xenopus oocytes. This technique is used to measure the properties of expressed ion channels either in populations (macropatch) or individually (single-channel recording). We focus on techniques to maximize the quality of oocyte preparation and seal generation. With all factors optimized, this technique gives a probability of successful seal generation over 90 percent. The process may be optimized differently by every researcher based on the factors he or she finds most important, and we present the approach that have lead to the greatest success in our hands.

This is intended as an introduction to patch clamp recording from Xenopus laevis oocytes. It covers vitelline membrane removal, formation of a gigaohm seal (gigaseal), and the optional conversion of the patch to the outside-out topology.

アフリカツメガエルの卵母細胞で発現イオンチャネルのパッチクランプ記録

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological ...

Microinjection of Xenopus Laevis Oocytes

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic transport. Because of its large nucleus and high density of nuclear pore complexes (NPCs), nuclear transport can be easily visualized in the Xenopus oocyte. Much insight into the mechanisms of nuclear import and export has been gained through use of this system (reviewed by Pant&eacute;, 2006). In addition, we have used microinjection of Xenopus oocytes to dissect the nuclear import pathways of several viruses that replicate in the host nucleus. 
Here we demonstrate the cytoplasmic microinjection of Xenopus oocytes with a nuclear import substrate. We also show preparation of the injected oocytes for visualization by thin-sectioning EM, including dissection, dehydration, and embedding of the oocytes into an epoxy embedding resin. Finally, we provide representative results for oocytes that have been microinjected with the capsid of the baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) or the parvovirus Minute Virus of Mice (MVM), and discuss potential applications of the technique.

Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by thin-sectioning electron microscopy.

アフリカツメガエル卵母細胞のマイクロインジェクション

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic ...

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to the original protocol that both streamline the procedure and increase sample uniformity.  First, we normalize all sperm volumes using freezing media that does not contain the cryoprotectant. Second, cryopreserved sperm are stored in cryovials instead of capillary tubes.  The rates of sperm freezing and thawing (&delta;&deg;C/time) are probably the two most critical variables to control in this procedure.  For this reason, do not substitute different tubes for those specified.  Working in teams of 2 it is possible to freeze the sperm of 100 males per team in ~2 hrs.  Sperm cryopreserved using this protocol has an average of 25% fertility (measured as the number of viable embryos generated in an in vitro fertilization divided by the total number of eggs fertilized) and this percent fertility is stable over many years.

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a high-throughput sperm cryopreservation protocol for zebrafish. Sperm cryopreserved using this protocol has an average of 25% fertility in subsequent vitro fertilization and is stable over many years.

ゼブラフィッシュ精子の凍結保存用ハイスループット法とインビトロ受精

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to ...

Visualizing RNA Localization in Xenopus Oocytes

RNA localization is a conserved mechanism of establishing cell polarity. Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to spatially restrict gene expression of Vg1 protein. Tight control of Vg1 distribution in this manner is required for proper germ layer specification in the developing embryo. RNA sequence elements in the 3' UTR of the mRNA, the Vg1 localization element (VLE) are required and sufficient to direct transport. To study the recognition and transport of Vg1 mRNA in vivo, we have developed an imaging technique that allows extensive analysis of trans-factor directed transport mechanisms via a simple visual readout. 
To visualize RNA localization, we synthesize fluorescently labeled VLE RNA and microinject this transcript into individual oocytes. After oocyte culture to allow transport of the injected RNA, oocytes are fixed and dehydrated prior to imaging by confocal microscopy. Visualization of mRNA localization patterns provides a readout for monitoring the complete pathway of RNA transport and for identifying roles in directing RNA transport for cis-acting elements within the transcript and trans-acting factors that bind to the VLE (Lewis et al., 2008, Messitt et al., 2008). We have extended this technique through co-localization with additional RNAs and proteins (Gagnon and Mowry, 2009, Messitt et al., 2008), and in combination with disruption of motor proteins and the cytoskeleton (Messitt et al., 2008) to probe mechanisms underlying mRNA localization.

Visualizing RNA Localization in Xenopus Oocytes

Visualization of in vivo RNA transport is accomplished by microinjection of fluorescently labeled RNA transcripts into Xenopus oocytes, followed by confocal microscopy.

可視化RNAの局在にアフリカツメガエル卵母細胞

RNA localization is a conserved mechanism of establishing cell polarity.  Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to ...

Tissue Determination Using the Animal Cap Transplant (ACT) Assay in Xenopus laevis

Many proteins play a dual role in embryonic development. Those that regulate cell fate determination in a specific tissue can also affect the development of a larger region of the embryo. This makes defining its role in a particular tissue difficult to analyze. For example, noggin overexpression in Xenopus laevis embryos causes the expansion of the entire anterior region, including the eye1,2. From this result, it is not known if Noggin plays a direct role in eye determination or that by causing an expansion of neural tissue, Noggin indirectly affects eye formation. Having this complex phenotype makes studying its eye-specific role in cell fate determination difficult to analyze. We have developed an assay that overcomes this problem. Taking advantage of the pluripotent nature of the Xenopus laevis animal cap 3, we have developed an assay to test the ability of gene product(s), like noggin or the eye field transcription factors (EFTFs), to transform caps into particular tissue or cell types by transplanting this tissue onto the side of the embryo 4. While we have found either Noggin protein treatment or a collection of transcription factors can determine retinal cell fate in animal caps, this procedure could be used to identify gene product(s) involved in specifying other tissues as well.

Tissue Determination Using the Animal Cap Transplant ACT Assay in Xenopus laevis

Animal caps overexpressing gene product(s) are transplanted to the flank of developing Xenopus laevis embryos in order to establish whether tissue is determined.

でアニマルキャップの移植（ACT）アッセイを用いて組織の決定アフリカツメガエル</em

Many proteins play a dual role in embryonic development. Those that regulate cell fate determination in a specific tissue can also affect the development ...

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may also be used to study the structure-function relationship for other ion channels and neurotransmitter receptors1. BK channels are widely expressed in different tissues and have been implicated in many physiological functions, including regulation of smooth muscle contraction, frequency tuning of inner hair cells and regulation of neurotransmitter release2-6. BK channels are activated by membrane depolarization and by intracellular Ca2+ and Mg2+ 6-9. Therefore, the protocol is designed to control both the membrane voltage and the intracellular solution. In this protocol, messenger RNA of BK channels is injected into Xenopus laevis oocytes (stage V-VI) followed by 2-5 days of incubation at 18&deg;C10-13. Membrane patches that contain single or multiple BK channels are excised with the inside-out configuration using patch clamp techniques10-13. The intracellular side of the patch is perfused with desired solutions during recording so that the channel activation under different conditions can be examined. To summarize, the mRNA of BK channels is injected into Xenopus laevis oocytes to express channel proteins on the oocyte membrane; patch clamp techniques are used to record currents flowing through the channels under controlled voltage and intracellular solutions.

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Ionic current of BK channels is recorded using patch clamp techniques. BK channels are expressed in Xenopus oocytes by injecting messenger RNA. The intracellular solution during patch clamp recordings is controlled by a perfusion system.

イオンチャネル研究のためのパッチクランプおよび灌流のテクニックで表さアフリカツメガエル卵母細胞

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may ...

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts

On a daily basis, cells are subjected to a variety of endogenous and environmental insults. To combat these insults, cells have evolved DNA damage checkpoint signaling as a surveillance mechanism to sense DNA damage and direct cellular responses to DNA damage. There are several groups of proteins called sensors, transducers and effectors involved in DNA damage checkpoint signaling (Figure 1). In this complex signaling pathway, ATR (ATM and Rad3-related) is one of the major kinases that can respond to DNA damage and replication stress. Activated ATR can phosphorylate its downstream substrates such as Chk1 (Checkpoint kinase 1). Consequently, phosphorylated and activated Chk1 leads to many downstream effects in the DNA damage checkpoint including cell cycle arrest, transcription activation, DNA damage repair, and apoptosis or senescence (Figure 1). When DNA is damaged, failing to activate the DNA damage checkpoint results in unrepaired damage and, subsequently, genomic instability. The study of the DNA damage checkpoint will elucidate how cells maintain genomic integrity and provide a better understanding of how human diseases, such as cancer, develop.
Xenopus laevis egg extracts are emerging as a powerful cell-free extract model system in DNA damage checkpoint research. Low-speed extract (LSE) was initially described by the Masui group1. The addition of demembranated sperm chromatin to LSE results in nuclei formation where DNA is replicated in a semiconservative fashion once per cell cycle.
The ATR/Chk1-mediated checkpoint signaling pathway is triggered by DNA damage or replication stress 2. Two methods are currently used to induce the DNA damage checkpoint: DNA damaging approaches and DNA damage-mimicking structures 3. DNA damage can be induced by ultraviolet (UV) irradiation, &gamma;-irradiation, methyl methanesulfonate (MMS), mitomycin C (MMC), 4-nitroquinoline-1-oxide (4-NQO), or aphidicolin3, 4. MMS is an alkylating agent that inhibits DNA replication and activates the ATR/Chk1-mediated DNA damage checkpoint 4-7. UV irradiation also triggers the ATR/Chk1-dependent DNA damage checkpoint 8. The DNA damage-mimicking structure AT70 is an annealed complex of two oligonucleotides poly-(dA)70 and poly-(dT)70. The AT70 system was developed in Bill Dunphy's laboratory and is widely used to induce ATR/Chk1 checkpoint signaling 9-12.
Here, we describe protocols (1) to prepare cell-free egg extracts (LSE), (2) to treat Xenopus sperm chromatin with two different DNA damaging approaches (MMS and UV), (3) to prepare the DNA damage-mimicking structure AT70, and (4) to trigger the ATR/Chk1-mediated DNA damage checkpoint in LSE with damaged sperm chromatin or a DNA damage-mimicking structure.

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts

Xenopus egg extract is a useful model system to investigate the DNA damage checkpoint. This protocol is for the preparation of Xenopus egg extracts and DNA damage checkpoint inducing reagents. These techniques are adaptable to a variety of DNA damaging approaches in the study of the DNA damage checkpoint signaling.