Name: manipulation and in vitro maturation of xenopus laevis oocytes, followed by intracytoplasmic sperm injection, to study embryonic development
Uploaded: 2015-02-09T15:00:00.000+00:00
Duration: 9 min 22 s
Description: Watch this Scientific Journal Video about Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development at JoVE.com

We are grateful to Gurdon laboratory members for useful discussion. K.M. is a Research Fellow at Wolfson College and is supported by the Herchel Smith Postdoctoral Fellowship and the Great Britain Sasakawa Foundation. Gurdon laboratory is supported by grants from the Wellcome Trust (RG69899) and MRC to J.B.G.

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The authors have nothing to disclose.

Nós aqui detalhe um novo método para esgotar fatores maternos ou overexpress fatores exógenos antes da fertilização. Este sistema requer dois micro-injecções, mas em vez disso ignora a cirurgia de sapos, utilizado no método de transferência 7,17 hospedeiro. É ideal para remover a etapa cirurgia sapo em termos de cuidados com os animais. Além disso, não temos de levar em conta a qualidade de rãs do sexo feminino de acolhimento para os experimentos de transferência, o que significa que podemos nos livrar de um fator biológico que afeta o sucesso dos experimentos. Portanto, neste sistema a qualidade dos oócitos obtidos a partir de rãs PMSG-condicionadas é um importante fator biológico que é a chave para as experiências bem-sucedidas. A qualidade dos oócitos pode ser julgado após a coleta de ovário ou após defolliculation. Se qualquer anormalidade for observada nestas fases, é ideal para coletar outro ovário de uma nova rã. Outro ponto em que você pode verificar a qualidade do ovócito é após a maturação do oócito. Se menos do que 80% de progesteronaoócitos tratados-e mostrar sinais de maturação, você pode não ser capaz de obter o número suficiente de embriões para análises posteriores. O uso de defolliculation enzimática em vez de defolliculation manual é também uma outra vantagem de se utilizar este sistema para reduzir o trabalho necessário para defolliculation. No entanto, ainda é possível que defolliculation manual pode dar um desenvolvimento melhor do que o tratamento enzimático. Como mostrado na Figura 3, quase 10% dos oócitos maturados in vitro podem alcançar o estágio natação girino. Estes dados são recolhidos a partir de 13 experimentos independentes, incluindo os relatados em 8 e novos experimentos de injeção. Método de transferência anfitrião precisa 75-150 ovócitos em cada tratamento para a obtenção de dados significativos uma vez que 30-60% dos oócitos transferidos podem chegar à fase neurula 17. O nosso método começa normalmente com 200-300 oócitos em cada grupo experimental, uma vez que aproximadamente 40-60% dos embriões clivados pode chegar afase resposta muscular. Estes dados sugerem que ambos os métodos de desenvolvimento suporta uma taxa razoável. Temos até agora obtido 10 sapos vivos de oócitos com injeção de controle oligo antisense com injecção de mRNA e controle utilizando esta técnica, indicando que esta abordagem apoia o desenvolvimento por meio de metamorfose. Nosso método de manipulação de oócitos-ICSI é uma oportunidade para testar o papel dos fatores maternos durante o desenvolvimento embrionário muito cedo, logo após a fertilização. Além disso, a sobre-expressão de factores de modificação da cromatina antes da fertilização pode tornar possível a remodelação da cromatina materna antes da fertilização para a compreensão estados cromatina materna necessário para o desenvolvimento. Esta estratégia também pode funcionar bem com sistemas de edição gene atuais, como a transcrição ativador-like efetoras nuclease (TALEN) 18,19 e CRISPR / CAS9 20,21 uma vez que estes podem ser expressas, mesmo antes da fertilização. Portanto, a nossa nova abordagem tem uma potentiAl de ser utilizado para muitas aplicações no futuro.

Xenopus laevis é um amplamente utilizado, poderoso organismo modelo para estudar o desenvolvimento 1. Isso ocorre porque os ovos de Xenopus são extraordinariamente grande (cerca de 1,2-1,4 mm, em comparação com congéneres de mamíferos sendo cerca de 0,1 mm) e abundante. Os ovos contêm componentes maternalmente sintetizados e armazenados, que são o suficiente para conduzir o desenvolvimento embrionário até meados de transição blastula (MBT, que ocorre na fase de 8-8,5 com células 4,000-8,000). MBT é acompanhada de ativação do genoma zygotic, que então produz produtos de genes embrionários que direcionam o desenvolvimento. Numerosos estudos teve como objetivo identificar fatores maternos importantes para o desenvolvimento. Muitos estudos baseiam-se na injecção de oligonucleótidos anti-sentido (oligos), incluindo oligonucleótidos de morfolino em embriões fertilizados, caso em que a degradação de proteínas maternas podem ser observados na fase de gástrula 2-4. Alternativamente, os ARNm são injectados para fertilizados inbryos perturbar funções de genes ou para traçar destino de proteínas sobre-expressos. No entanto, a injecção nos embriões em estágio de uma célula normalmente não afeta os níveis de proteínas maternos expressão nas fases embrionárias muito cedo antes MBT. Heasman e Wylie estabelecido o método de transferência de acolhimento para superar esse problema 5. No método, os oócitos desfoliculados manualmente são injectados com oligonucleótidos anti-sentido e transferidos para fêmeas hospedeiras 6. As proteínas são reprimidos antes da fertilização, de modo que os papéis de proteínas downregulated no desenvolvimento embrionário precoce pode ser examinado. Este método de depleção materna levou à identificação de vários papéis de desenvolvimento únicas de proteínas maternas, como revisado em 7. Neste relatório, detalhamos o nosso método desenvolvido recentemente, em que a depleção materna ou sobre-expressão de mRNA antes da fertilização é conseguido sem defolliculation manual e transferência de acolhimento8. Defolliculation manual requer muito tempo e transferência de acolhimento muitas vezes precisa de técnicas hábeis e a licença específica para a cirurgia animal, dificultando, assim, o uso frequente de método de depleção materna. Defolliculation e transferência de acolhimento são substituídos por defolliculation enzimática 9,10 e injeção intracitoplasmática de espermatozóides (ICSI) 11-13, respectivamente. ICSI a ovos foi originalmente usado para produzir rãs transgênicos 12. Esperma e embrionárias núcleos também foram transplantadas para in vitro de oócitos de anfíbios amadureceu 11,14,15. Aqui, vamos mostrar o nosso método passo-a-passo para injetar esperma para oócitos maturados in vitro que foram pré-injectados com oligos anti-sentido ou mRNA.

<table><tbody><tr><td>Pregnant Mare Serum Gonadotropin (PMSG)&amp;nbsp;</td><td>MSD Animal Health</td><td>Vm 01708/4309</td><td>PMSG-Intervet 5000iu powder and solvent for solution for injection</td></tr><tr><td>Ethyl 3-aminobenzoate methanesulfonate salt (MS222)</td><td>Sigma</td><td>A5040</td><td>For anesthesia</td></tr><tr><td>Liberase TM Research Grade</td><td>Roche</td><td>05 401 127 001</td><td>For oocyte defolliculation. Store at -20&amp;nbsp;&amp;#176;C.</td></tr><tr><td>Drummond Nanoject</td><td>Drummond Scientific Company</td><td>3-000-205/206</td><td>For microinjection</td></tr><tr><td>glass capillary&amp;nbsp;</td><td>Alpha laboratories</td><td>7&amp;rdquo; Drummond #3-000-203-G/XL</td><td>For microinjection</td></tr><tr><td>Micropipette Puller&amp;nbsp;</td><td>SUTTER Instrument</td><td>Model D-97</td><td>For microinjection</td></tr><tr><td>UltraPure Agarose</td><td>Invitrogen</td><td>16500-500</td><td>For &lt;em&gt;in vitro&lt;/em&gt; maturation and ICSI</td></tr><tr><td>14 ml ultra-clear centrifuge tube&amp;nbsp;</td><td>Beckman Coulter United Kingdom Ltd</td><td>344060</td><td>For sperm purification</td></tr><tr><td>OptiPrep Density Gradient Medium (Iodixanol)</td><td>Sigma</td><td>D1556</td><td>For sperm purification</td></tr><tr><td>Digitonin</td><td>Sigma</td><td>D141</td><td>Cell permeabilization reagent</td></tr><tr><td>Shaker</td><td>Hybaid&amp;nbsp;</td><td>HB-SHK-1</td><td>For oocyte defolliculation</td></tr><tr><td>Dissecting microscope (Stereo zoom microscope)</td><td>ZEISS</td><td>Semi SV6</td><td>For oocyte collection and microinjection</td></tr><tr><td>50 &amp;mu;m pore filter</td><td>CellTrics</td><td>04-0042-2317</td><td>For sperm purification</td></tr><tr><td>Ultracentrifuge</td><td>Beckman Coulter</td><td>Optima L-100XP</td><td>For sperm purification</td></tr><tr><td>50 ml centrifuge tube</td><td>Cellstar Greiner Bio-One</td><td>227261 or 210261</td><td>Oocyte collection and defolliculation reaction</td></tr><tr><td>15 ml centrifuge tube</td><td>FALCON</td><td>352097</td><td>For sperm purification</td></tr><tr><td>90 mm Petri dish&amp;nbsp;</td><td>Thermo Scientific</td><td>101VR20/C</td><td></td></tr><tr><td>Easy-Grip Cell Culture Dish, 60&amp;nbsp;x&amp;nbsp;15 mm</td><td>FALCON</td><td>353004</td><td></td></tr><tr><td>Easy-Grip Cell Culture Dish, 35&amp;nbsp;x&amp;nbsp;15 mm</td><td>FALCON</td><td>351008</td><td></td></tr></tbody></table>

manipulation and in vitro maturation of xenopus laevis oocytes, followed by intracytoplasmic sperm injection, to study embryonic development

Amphibian eggs have been widely used to study embryonic development. Early embryonic development is driven by maternally stored factors accumulated during oogenesis. In order to study roles of such maternal factors in early embryonic development, it is desirable to manipulate their functions from the very beginning of embryonic development. Conventional ways of gene interference are achieved by injection of antisense oligonucleotides (oligos) or mRNA into fertilized eggs, enabling under- or over-expression of specific proteins, respectively. However, these methods normally require more than several hours until protein expression is affected, and, hence, the interference of gene functions is not effective during early embryonic stages. Here, we introduce an experimental system in which expression levels of maternal proteins can be altered before fertilization. Xenopus laevis oocytes obtained from ovaries are defolliculated by incubating with enzymes. Antisense oligos or mRNAs are injected into defolliculated oocytes at the germinal vesicle (GV) stage. These oocytes are in vitro matured to eggs at the metaphase II (MII) stage, followed by intracytoplasmic sperm injection (ICSI). By this way, up to 10% of ICSI embryos can reach the swimming tadpole stage, thus allowing functional tests of specific gene knockdown or overexpression. This approach can be a useful way to study roles of maternally stored factors in early embryonic development.

O desenvolvimento embrionário de embriões utilizando ICSI em oócitos maturados in vitro foi analisado (Figura 3A). As taxas de maturação dos oócitos GV para o palco MII são variáveis ​​e depende muito da qualidade do oócito. Em boas experiências, quase 100% dos oócitos GV responder a progesterona e mostrar sinais de maturação do oócito, finalmente se tornando ovos na fase MII. Todos os oócitos foram submetidos a ICSI e cerca de 25% dos ovos injectados clivados (Figura 3A, n = 13 para o controlo scrambled oócitos injectados com oligo e n = 7 para não oócitos injectados com oligo). Cerca de 60% ou 80% dos embriões clivados, produzidos a partir de oócitos injectados com oligo de controlo ou oócitos não injectados, respectivamente, atingiram o estádio de blástula / gástrula. Entre os embriões de blástula / gástrula, cerca de metade dos embriões injectados com amostras em oligo foram de boa qualidade (quase nenhum sinal de clivagem anormal e apoptose), enquanto que 82% dos embriões de blástula / gástrula foram de boa qualidade em namostras em injectados (Figura 3A). Por fim, 41% e 11% dos embriões injectados clivados em amostras de oligo-atingiu a resposta muscular e as fases natação girino, respectivamente, enquanto 60% e 29% dos embriões clivados em amostras não injectados fez (Figura 3A). Estes embriões são ICSI a mistura de embriões normais e anormais (Figura 3B). Alguns deles sofrem metamorfose e desenvolver a amadurecer rãs 8. Estes resultados sugerem que a injecção de oligonucleótidos anti-sentido em oócitos GV, seguido por IVM e ICSI, permite o desenvolvimento embrionário inicial eficiente. Embora a injeção de si oligos antisense diminui o desenvolvimento embrionário, que ainda são capazes de obter embriões suficientes para muitos fins experimentais, como verificar as taxas de desenvolvimento, RT-PCR, Western Blot e assim por diante. <img alt="Figura 1" src="/files/ftp_upload/52496/52496fig1highres.jpg" /> Figo<html> ure 1: Os exemplos típicos de oócitos de Xenopus laevis de boa qualidade ou má qualidade de experimentos in vitro de maturação. (A) Um exemplo de oócitos de má qualidade. Por exemplo, os oócitos que mostram pigmentação irregular não são utilizadas para as experiências subsequentes. Cada oócito de Xenopus laevis é de cerca de 1,2-1,4 mm de diâmetro. (B) Um oócito parcialmente desfoliculados. A metade direita do oócito é coberta por células foliculares, os quais podem ser distinguidas pela presença de vasos sanguíneos. Uma seta mostra uma área livre de células do folículo e em que a agulha de injeção é injetado. (C) Um exemplo de oócitos de boa qualidade, que são do mesmo tamanho e mostram hemisférios animais uniformemente pigmentadas com claro contraste entre o hemisfério animal e do hemisfério vegetal. 2496 / 52496fig2highres.jpg &quot;/&gt; Figura 2:. Oócitos de Xenopus laevis, antes e após a maturação Após a maturação do oócito, claras manchas brancas aparecem no topo da hemisférios animais e células foliculares são descascadas. Cada laevis oócito Xenopus é de aproximadamente 1 mm de diâmetro. <img alt="Figura 3" src="/files/ftp_upload/52496/52496fig3highres.jpg" /> Figura 3: Desenvolvimento de embriões de ICSI, produzidos a partir de oócitos maturados in vitro. (A) O desenvolvimento de embriões de ICSI para cada fase é resumido. Os oócitos foram injectados com oligonucleótidos anti-sentido de controlo scrambled (controlo) de injecção de oligo ou sem injecção (não injectável), seguido por IVM e ICSI. O número correspondente de embriões em cada fase é mostrado acima das barras. A média ± SEM é mostrado. N = 4-13 experiências independentes / f diferenteemales. (B) Exemplos de sobrevivência de embriões de ICSI. Estes embriões nos estágios tailbud foram produzidos de uma experiência, em que cerca de 200 oócitos foram usadas como um material de partida.

Watch this Scientific Journal Video about Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development at JoVE.com

Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development

We describe methods of manipulating Xenopus laevis immature oocytes, in vitro maturation of oocytes to eggs, and intracytoplasmic sperm injection. This protocol allows degradation of some maternal proteins and overexpression of genes of interest at fertilization, and hence is valuable to study roles of specific factors in early embryonic development.

Manipulação e<em&gt; In Vitro</em&gt; Maturação<em&gt; Xenopus laevis</em&gt; Oócitos, seguido de injeção intracitoplasmática de espermatozóide, para estudar o desenvolvimento embrionário

Amphibian eggs have been widely used to study embryonic development. Early embryonic development is driven by maternally stored factors accumulated during ...

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Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development

22.5K visualizações.  University of Cambridge. We describe methods of manipulating Xenopus laevis immature oocytes, in vitro maturation of oocytes to eggs, and intracytoplasmic sperm injection. This protocol allows degradation of some maternal proteins and overexpression of genes of interest at fertilization, and hence is valuable to study roles of specific factors in early embryonic development.

Vídeo: Manipulation and In Vitro Maturation of Xenopus laevis Oocytes, Followed by Intracytoplasmic Sperm Injection, to Study Embryonic Development

Using Confocal Analysis of Xenopus laevis to Investigate Modulators of Wnt and Shh Morphogen Gradients

This protocol describes a method to visualise ligands distributed across a field of cells. The ease of expressing exogenous proteins, together with the large size of their cells in early embryos, make Xenopus laevis a useful model for visualising GFP-tagged ligands. Synthetic mRNAs are efficiently translated after injection into early stage Xenopus embryos, and injections can be targeted to a single cell. When combined with a lineage tracer such as membrane tethered RFP, the injected cell (and its descendants) that are producing the overexpressed protein can easily be followed. This protocol describes a method for the production of fluorescently tagged Wnt and Shh ligands from injected mRNA. The methods involve the micro dissection of ectodermal explants (animal caps) and the analysis of ligand diffusion in multiple samples. By using confocal imaging, information about ligand secretion and diffusion over a field of cells can be obtained. Statistical analyses of confocal images provide quantitative data on the shape of ligand gradients. These methods may be useful to researchers who want to test the effects of factors that may regulate the shape of morphogen gradients.

Using Confocal Analysis of Xenopus laevis to Investigate Modulators of Wnt and Shh Morphogen Gradients

The manuscript here provides a simple set of methods for analysing the secretion and diffusion of fluorescently tagged ligands in Xenopus. This provides a context for testing the ability of other proteins to modify ligand distribution and allowing experiments that may give insight into mechanisms regulating morphogen gradients.

Utilizando Análise de confocal<em&gt; Xenopus laevis</em&gt; Para Investigar moduladores de Wnt e Shh morfogénio gradientes

This protocol describes a method to visualise ligands distributed across a field of cells. The ease of expressing exogenous proteins, together with the ...

Biologia do Desenvolvimento

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, cells from the roof of the blastocoel are pluripotent. These cells can be isolated, and programmed to generate various tissues through manipulation of genes expression or induction by morphogens. In this manuscript protocols are described for the use of Xenopus laevis blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development. These protocols allow the investigation of fate acquisition, cell migration behaviors, and cell autonomous and non-autonomous properties. The blastocoel roof explants can be cultured in a serum-free defined medium and grafted into host embryos. This transplantation into an embryo allows the investigation of the long-term lineage commitment, the inductive properties, and the behavior of transplanted cells in vivo. These assays can be exploited to investigate molecular mechanisms, cellular processes and gene regulatory networks underlying neural development. In the context of regenerative medicine, these assays provide a means to generate neural-derived cell types in vitro that could be used in drug screening.

Stem cell-like Xenopus Embryonic Explants to Study Early Neural Developmental Features In Vitro and In Vivo

In Xenopus embryos, cells from the roof of the blastocoel are pluripotent and can be programmed to generate various tissues. Here, we describe protocols to use amphibian blastocoel roof explants as an assay system to investigate key in vivo and in vitro features of early neural development.

Stem Cell-like<em&gt; Xenopus</em&gt; Embrionárias explantes Estudar características Neural desenvolvimento precoce<em&gt; In Vitro</em&gt; E<em&gt; In Vivo</em

Understanding the genetic programs underlying neural development is an important goal of developmental and stem cell biology. In the amphibian blastula, ...

Functional Cloning Using a Xenopus Oocyte Expression System

Identification of genes responsible for embryonic induction poses a number of challenges; to name a few, secreted molecules of interest may be low in abundance, may not be secreted but tethered to the signaling cell(s), or may require the presence of binding partners or upstream regulatory molecules. Thus in a search for gene products capable of eliciting an early lens-inductive response in competent ectoderm, we utilized an expression cloning system that would allow identification of paracrine or juxtacrine factors as well as transcriptional or other regulatory proteins. Pools of mRNA were injected into Xenopus oocytes, and responding tissue placed directly on the oocytes and co-cultured. Following functional cloning of ldb1 from a neural plate stage cDNA library based on its ability to elicit the expression of the early lens placode marker foxe3 in lens-competent animal cap ectoderm, we characterized the mRNA expression pattern, and assayed developmental progression following overexpression or knockdown of ldb1. This system is suitable in a very wide variety of contexts where identification of an inducer or its upstream regulatory molecules is sought using a functional response in competent tissue.

Functional Cloning Using a Xenopus Oocyte Expression System

We describe a Xenopus oocyte and animal cap system for the expression cloning of genes capable of inducing a response in competent ectoderm, and discuss techniques for the subsequent analysis of such genes. This system is useful in the functional identification of a wide range of gene products.

Clonagem Funcional Utilizando um<em&gt; Xenopus</em&gt; Oocyte Sistema de Expressão

Identification of genes responsible for embryonic induction poses a number of challenges; to name a few, secreted molecules of interest may be low in ...

Technique to Target Microinjection to the Developing Xenopus Kidney

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

Technique to Target Microinjection to the Developing Xenopus Kidney

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

Técnica ao Target microinjeção para o desenvolvimento<em&gt; Xenopus</em&gt; Kidney

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

Functional Manipulation of Maternal Gene Products Using In Vitro Oocyte Maturation in Zebrafish

Cellular events that take place during the earliest stages of animal embryonic development are driven by maternally derived gene products deposited into the developing oocyte. Because these events rely on maternal products which typically act very soon after fertilization-that preexist inside the egg, standard approaches for expression and functional reduction involving the injection of reagents into the fertilized egg are typically ineffective. Instead, such manipulations must be performed during oogenesis, prior to or during the accumulation of maternal products. This article describes in detail a protocol for the in vitro maturation of immature zebrafish oocytes and their subsequent in vitro fertilization, yielding viable embryos that survive to adulthood. This method allows the functional manipulation of maternal products during oogenesis, such as the expression of products for phenotypic rescue and tagged construct visualization, as well as the reduction of gene function through reverse-genetics agents.

Functional Manipulation of Maternal Gene Products Using In Vitro Oocyte Maturation in Zebrafish

An optimized protocol for the in vitro maturation of zebrafish oocytes used for the manipulation of maternal gene products is presented here.

Manipulação funcional do gene materno produtos Usando<em&gt; In Vitro</em&gt; Maturação do oócito em Zebrafish

Cellular events that take place during the earliest stages of animal embryonic development are driven by maternally derived gene products deposited into ...

Visualization and Quantitative Analysis of Embryonic Angiogenesis in Xenopus tropicalis

Blood vessels supply oxygen and nutrients throughout the body, and the formation of the vascular network is under tight developmental control. The efficient in vivo visualization of blood vessels and the reliable quantification of their complexity are key to understanding the biology and disease of the vascular network. Here, we provide a detailed method to visualize blood vessels with a commercially available fluorescent dye, human plasma acetylated low density lipoprotein DiI complex (DiI-AcLDL), and to quantify their complexity in Xenopus tropicalis. Blood vessels can be labeled by a simple injection of DiI-AcLDL into the beating heart of an embryo, and blood vessels in the entire embryo can be imaged in live or fixed embryos. Combined with gene perturbation by the targeted microinjection of nucleic acids and/or the bath application of pharmacological reagents, the roles of a gene or of a signaling pathway on vascular development can be investigated within one week without resorting to sophisticated genetically engineered animals. Because of the well-defined venous system of Xenopus and its stereotypic angiogenesis, the sprouting of pre-existing vessels, vessel complexity can be quantified efficiently after perturbation experiments. This relatively simple protocol should serve as an easily accessible tool in diverse fields of cardiovascular research.

Visualization and Quantitative Analysis of Embryonic Angiogenesis in Xenopus tropicalis

This protocol demonstrates a fluorescence-based method to visualize the vasculature and to quantify its complexity in Xenopus tropicalis. Blood vessels can be imaged minutes after the injection of a fluorescent dye into the beating heart of an embryo after genetic and/or pharmacological manipulations to study cardiovascular development in vivo.

Visualização e Análise Quantitativa da Angiogênese Embrionária<em&gt; Xenopus tropicalis</em

Blood vessels supply oxygen and nutrients throughout the body, and the formation of the vascular network is under tight developmental control. The ...

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.

Microinjeção de Oócitos Xenopus laevis

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

Biologia

Fertilization of Xenopus oocytes using the Host Transfer Method

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to generate maternal-effect mutant animals. Additionally, many of the techniques to overexpress or inhibit gene function in organisms such as Xenopus and zebrafish fail to sufficiently target critical maternal signaling pathways, such as Wnt signaling. In Xenopus, manipulating gene function in cultured oocytes and subsequently fertilizing them can ameliorate these problems to some extent. Oocytes are manually defolliculated from donor ovary tissue, injected or treated in culture as desired, and then stimulated with progesterone to induce maturation. Next, the oocytes are introduced into the body cavity of an ovulating host female frog, whereupon they will be translocated through the host's oviduct and acquire modifications and jelly coats necessary for fertilization. The resulting embryos can then be raised to the desired stage and analyzed for the effects of any experimental perturbations. This host-transfer method has been highly effective in uncovering basic mechanisms of early development and allows a wide range of experimental possibilities not available in any other vertebrate model organism.

Fertilization of Xenopus oocytes using the Host Transfer Method

Procedure for fertilizing Xenopus oocytes by the host transfer method.

Fertilização de Oócitos Xenopus Utilizando o método de transferência do host

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

Live-cell Imaging and Quantitative Analysis of Embryonic Epithelial Cells in Xenopus laevis

Embryonic epithelial cells serve as an ideal model to study morphogenesis where multi-cellular tissues undergo changes in their geometry, such as changes in cell surface area and cell height, and where cells undergo mitosis and migrate. Furthermore, epithelial cells can also regulate morphogenetic movements in adjacent tissues1. A traditional method to study epithelial cells and tissues involve chemical fixation and histological methods to determine cell morphology or localization of particular proteins of interest. These approaches continue to be useful and provide "snapshots" of cell shapes and tissue architecture, however, much remains to be understood about how cells acquire specific shapes, how various proteins move or localize to specific positions, and what paths cells follow toward their final differentiated fate. High resolution live imaging complements traditional methods and also allows more direct investigation into the dynamic cellular processes involved in the formation, maintenance, and morphogenesis of multicellular epithelial sheets. Here we demonstrate experimental methods from the isolation of animal cap tissues from Xenopus laevis embryos to confocal imaging of epithelial cells and simple measurement approaches that together can augment molecular and cellular studies of epithelial morphogenesis.

Live-cell Imaging and Quantitative Analysis of Embryonic Epithelial Cells in Xenopus laevis

Xenopus embryonic epithelia are an ideal model system to study cell behaviors such as polarity development and shape change during epithelial morphogenesis. Traditional histology of fixed samples is increasingly being complemented by live-cell confocal imaging. Here we demonstrate methods to isolate frog tissues and visualize live epithelial cells and their cytoskeleton using live-cell confocal microscopy.

Em células vivas, Imagem e Análise Quantitativa de células embrionárias epiteliais em Xenopus laevis</em

Embryonic epithelial cells serve as an ideal model to study morphogenesis where multi-cellular tissues undergo changes in their geometry, such as changes ...

Production of Transgenic Xenopus laevis by Restriction Enzyme Mediated Integration and Nuclear Transplantation

Stable integration of cloned gene products into the Xenopus genome is necessary to control the time and place of expression, to express genes at later stages of embryonic development, and to define how enhancers and promoters regulate gene expression within the embryo. The protocol demonstrated here can be used to efficiently produce transgenic Xenopus laevis embryos. This transgenesis approach involves three parts: 1. Sperm nuclei are isolated from adult X. laevis testis by treatment with lysolecithin, which permeabilizes the sperm plasma membrane. 2. Egg extract is prepared by low speed centrifugation, addition of calcium to cause the extract to progress to interphase of the cell cycle, and a high-speed centrifugation to isolate interphase cytosol. 3. Nuclear transplantation: the nuclei and extract are combined with the linearized plasmid DNA to be introduced as the transgene and a small amount of restriction enzyme. During a short reaction, egg extract partially decondenses the sperm chromatin and the restriction enzyme generates chromosomal breaks that promote recombination of the transgene into the genome. The treated sperm nuclei are then transplanted into unfertilized eggs. Integration of the transgene usually occurs prior to the first embryonic cleavage such that the resulting embryos are not chimeric. These embryos can be analyzed without any need to breed to the next generation, allowing for efficient and rapid generation of transgenic embryos for analyses of promoter and gene function. Adult X. laevis resulting from this procedure also propagate the transgene through the germline and can be used to generate lines of transgenic animals for multiple purposes.

Production of Transgenic Xenopus laevis by Restriction Enzyme Mediated Integration and Nuclear Transplantation

This video protocol demonstrates a method for generating transgenic Xenopus laevis by introduction of transgenes into sperm nuclei followed by nuclear transplantation into unfertilized eggs.

Produção de transgênicos Xenopus laevis Por Restrição Integração Mediada por Enzima e Transplante Nuclear

Stable integration of cloned gene products into the Xenopus genome is necessary to control the time and place of expression, to express genes at later ...

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