Todos os membros da Universidade de Washington em St. Louis Cardiac Molecular Laboratório de Engenharia. A Burroughs Bem-vindo Fundo Prémio Carreira na Interface Científica - 1010299 (para JS).

<ol>
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Os autores não têm nada a revelar.

A vaselina oócito tensão lacuna técnica braçadeira cut-aberto permite a resolução rápida de dados, baixo ruído, maior controle sobre a solução interna e composição da solução externa e gravações estáveis ​​através de protocolos relativamente longos 19. Estas vantagens definir esta técnica além de o grampo de voltagem de dois eléctrodos padrão e técnicas de fixação de membranas. Apesar de equipamento especializado é necessária e que o protocolo é relativamente difícil, muito poucos problemas ocorrem quando o sistema foi otimizado. Isto permite uma gravação reprodutíveis de sódio (HNA V 1.5) e outros canais de activação rápida. Os passos mais críticos no protocolo são a colocação da câmara superior no oócito eo empalamento com o eletrodo V1. O aperto da selagem entre a célula e os bordos dos orifícios da câmara tem um grande impacto sobre a qualidade da gravação. A câmara de topo deve ser empurrado para baixo no celular para atingir o mais alto possível resistência sem danificar o óvulo. Isso será necessário fazer o bojo do oócito e achatar, mas a experiência ea consideração da qualidade de célula é necessário para determinar a pressão ideal para evitar a ruptura. Gravação rápida requer a utilização da maior abertura da pipeta possível que pode ser utilizado de forma consistente, sem danificar as células. Especial atenção deve ser dada para o cone da pipeta, que deve ser rasa o suficiente para não expandir significativamente a ferida como a ponta da pipeta está inserido. Impalement deve ser feita devagar e com cuidado, imediatamente parar o avanço do eléctrodo, quando do aparecimento do potencial de membrana de leitura. Danos à membrana do ovócito e menos de selos perfeitos oócito / Câmara pode levar a altas correntes de fuga. Altas correntes de fuga sempre deteriorar a qualidade das gravações. Assim, as gravações devem ter sempre as correntes de fuga baixas (de preferência &lt;150-200 NA). Circuito de compensação do amplificador, o uso de P / N em linha vazamento-coprocedimentos rrection, ou off-line pode compensar atual vazamento. Solução de problemas deve começar por duplo controlo que todos os componentes estejam conectados corretamente ou ajustados, que geralmente resolve a maioria dos problemas. Durante a preparação ea própria experiência, especial atenção deve ser dada a todos os níveis de fluidos derramados ou transbordando e cristalizada KCl como estes podem conectar eletricamente compartimentos que se destinam a ser isolado. Se o sistema se comporta de forma inesperada, procurar ligações em falta ou indesejados entre pontes e câmaras. As bolhas de ar dentro das pontes de agar, nas extremidades das pontes agar, ou preso por baixo da célula, também pode causar problemas de conectividade que são difíceis de detectar. As modificações, tal como descrito acima, são necessárias para executar fluorometria fixador de tensão (VCF) juntamente com COVG. A modificação principal envolve o uso de um design banho alterada. A fim de acomodar a utilização de uma objectiva de 40x de imersão em águano microscópio, o banho câmara superior deve ser maior do que seria necessário para uma configuração de corte de padrão aberto. Outros aspectos e necessidades de equipamentos de gravação de VCF no modo COVG são semelhantes a gravação VCF em dois eletrodos modo de tensão-clamp 14. Conforme salientado anteriormente, a principal vantagem da técnica COVG é o controle de tensão muito mais rápido e preciso em relação ao TEVC num emplastro de membrana que expressa tanto mais canais de iões que podem ser atingidas em sistemas de expressão de células de mamíferos. Assim, a técnica é ideal para a FCR e gating estudos actuais, onde tanto alta resolução temporal e os números de canal elevadas são necessárias para sinais detectáveis. Embora, em princípio, as trocas de soluções tanto extra e intracelulares são possíveis, a sua integridade e velocidade da troca definir algumas limitações em certos tipos de experimentos. Como mostrado na Figura 5, a taxa de equilíbrio de concentrações iónicas entre o citoplasma e o cham menorber é bastante lento seguinte saponina permeabilização. Mudando concentrações iônicas deve, portanto, ser considerados durante longos experimentos antes da célula que chegam a um estado estacionário. As taxas de câmbio pode variar em grande medida, dependendo das condições. Expressão alta do canal, grande força motriz, e maior resultado temperatura em taxas mais rápidas. Na nossa experiência, a célula foi arrefecida a 19 ° C, a expressão do canal era moderada, e a carga líquida conduzido pelos protocolos de IV foi mínima, devido à direcção da corrente mudando. Nesses ambientes a técnica COVG normal é inferior a várias configurações de patch-clamp. Para aplicações que requerem COVG substituição rápida do meio citoplasmático pode ser utilizada uma cânula de perfusão. No futuro, câmaras COVG projetados com portas internas de perfusão pode permitir um melhor controle sobre as características taxas de soluções extracelulares.

Técnicas de fixação de tensão especializados permitir a gravação de correntes iônicas de potenciais de membrana controladas. Amplamente utilizado braçadeira de tensão de dois eletrodos (TEVC) e técnicas de patch clamp fornecer informações eletrofisiológico confiável sobre as propriedades de muitos canais iônicos. No entanto, ambos os métodos têm desvantagens que impedem a obtenção de dados confiáveis ​​para os canais de sódio dependentes da voltagem rápidos e outros canais de ativação rápida nas membranas, como as de oócitos de Xenopus. Os laboratórios Bezanilla e Stefani, consequentemente, desenvolveu a técnica lacuna vaselina braçadeira de tensão cut-aberto (COVG) para ovócitos 2. A técnica tem sido amplamente aplicada para gravar, Na +, K +, Ca 2 + e canais de 3-8. Durante a gravação COVG, uma membrana do oócito expressando a proteína heteróloga é dividido em três regiões. Os dados de corrente iônica é gravado a partir da região superior do oócito como obanho em torno da região superior é presa a um potencial de comando, que pode ser fácil e rapidamente mudado. Os guardas região meio contra correntes de fuga ao ser fixada ao mesmo potencial que a região superior 9. A região inferior é onde a abertura do oócito (cut-open) ocorre através do uso de uma solução de saponina ou uma cânula. Química ou a abertura manual da membrana na região do fundo permite um controlo do potencial interno, que está fixada ao solo, e torna a célula contígua com a solução interior da câmara inferior. Perfusão de soluções para a câmara inferior pode ajustar as propriedades do ambiente interno, enquanto troca da solução na câmara de topo altera o ambiente externo. <img alt="Figura 1" fo:content-width="5in" fo:src="/files/ftp_upload/51040/51040fig1highres.jpg" src="/files/ftp_upload/51040/51040fig1.jpg" width="500px" /> Figura 1. Oocyte Cut-Open Voltage-Clamp Bath Setup Diagram. (A) Topabaixo da vista dos três banhos separados um do outro. As dimensões das câmaras para COVG são apresentados na figura. (B) Vista lateral da configuração banhos em posição de teste. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51040/51040fig1highres.jpg" target="_blank">Clique aqui para ver a imagem ampliada</a> . As vantagens da técnica COVG incluem baixo nível de ruído atual (1 nA a 3 kHz), o controle da composição iônica dos meios externos, a capacidade de modular os meios de comunicação interna, resolução de tempo rápido (20-100 constante ms de tempo de decaimento do capacidade transitória), e gravações estáveis ​​por várias horas 9. As desvantagens são que requer equipamento especializado e é mais difícil de realizar em comparação com dois de fixação de tensão de eléctrodo (TEVC) 10. Embora a abordagem COVG requer equipamentos altamente especializados e elementos processuais complexas, pode permitir a aquisição de valiosodados eletrofisiológicos capazes. Estes dados, como gating correntes com cinética rápida e correntes cauda 4, podem ser gravadas sem alguns dos problemas associados com outros protocolos de fixação de tensão, incluindo canal degradado. Pequenas modificações na configuração COVG pode permitir o uso de controladores de temperatura e fluorometria braçadeira de tensão (VCF). A inclusão de elementos de fluorometria braçadeira de tensão dentro da montagem COVG pode aumentar a saída de dados, conferindo a capacidade de monitorar mudanças conformacionais de proteínas e ao mesmo tempo de gravação atual 11-13.

<table border="0" cellpadding="0" cellspacing="0" width="515">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">External Solution</td>
			<td style="width:131px;">Brand</td>
			<td style="width:72px;">Catalog Number</td>
			<td style="width:124px;">[Final], weight, or volume</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">N-methyl-D-glucamine (NMDG)</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M2004</td>
			<td style="width:124px;">25mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">MES Sodium Salt</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M5057</td>
			<td style="width:124px;">90mM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">HEPES</td>
			<td style="width:131px;">Research Products International</td>
			<td style="width:72px;">H75030</td>
			<td style="width:124px;">20mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Calcium hydroxide</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">239232</td>
			<td style="width:124px;">2mM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">MES Hydrate</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M8250</td>
			<td style="width:124px;">variable (pH to 7.4)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Internal Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">N-methyl-D-glucamine (NMDG)</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M2004</td>
			<td style="width:124px;">105mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">MES Sodium Salt</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M5057</td>
			<td style="width:124px;">10mM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">HEPES</td>
			<td style="width:131px;">Research Products International</td>
			<td style="width:72px;">H75030</td>
			<td style="width:124px;">20mM</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:189px;">Ethylene glycol-bis(2-aminoethylether)-N,N,N&#39;,N&#39;-tetraacetic acid (EGTA)</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">E4378</td>
			<td style="width:124px;">2mM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">MES Hydrate</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M8250</td>
			<td style="width:124px;">variable (pH to 7.4)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Depolarizing Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">KCl</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">221473</td>
			<td style="width:124px;">110mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Magnesium chloride</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M8266</td>
			<td style="width:124px;">1.5mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Calcium Chloride</td>
			<td style="width:131px;">Caisson</td>
			<td style="width:72px;">C021</td>
			<td style="width:124px;">0.8mM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">HEPES</td>
			<td style="width:131px;">Research Products International</td>
			<td style="width:72px;">H75030</td>
			<td style="width:124px;">10mM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Pipet Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">KCl</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">221473</td>
			<td style="width:124px;">3M</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:189px;">Saponin Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Saponin</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">47036</td>
			<td style="width:124px;">0.125g</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Internal Solution</td>
			<td style="width:131px;">See above</td>
			<td style="width:72px;"></td>
			<td style="width:124px;">50mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Agar Bridge Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">N-methyl-D-glucamine (NMDG)</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M2004</td>
			<td style="width:124px;">100ml of 1M</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">HEPES</td>
			<td style="width:131px;">Research Products International</td>
			<td style="width:72px;">H75030</td>
			<td style="width:124px;">1.2g</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">MES Hydrate</td>
			<td style="width:131px;">Sigma-Aldrich</td>
			<td style="width:72px;">M8250</td>
			<td style="width:124px;">variable (pH to 7.4)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">Granulated Agar</td>
			<td style="width:131px;">Research Products International</td>
			<td style="width:72px;">A20250</td>
			<td align="right" style="width:124px;">3%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;"></td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">NMDG Storage Solution</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:189px;">NMDG, HEPES, MES Hydrate solution</td>
			<td style="width:131px;">see above</td>
			<td style="width:72px;"></td>
			<td style="width:124px;">40ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:189px;">Water</td>
			<td style="width:131px;"></td>
			<td style="width:72px;"></td>
			<td style="width:124px;">60ml</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Name of Material/ Equipment</td>
			<td style="width:148px;">Company</td>
			<td style="width:144px;">Catalog Number</td>
			<td style="width:285px;">Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">High Performance Oocyte Clamp</td>
			<td style="width:148px;">Dagan</td>
			<td style="width:144px;">CA-1B</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Data Acquisition System</td>
			<td style="width:148px;">Axon CNS</td>
			<td style="width:144px;">&#160;Digidata 1440A</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Oscilloscope</td>
			<td style="width:148px;">Tektronix&#160;</td>
			<td style="width:144px;">TDS 210</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Rack Power Filter</td>
			<td style="width:148px;">APC&#160;</td>
			<td style="width:144px;">G5</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:149px;">Heating/Cooling Bath Temperature Controller</td>
			<td style="width:148px;">Dagan</td>
			<td style="width:144px;">HCC-100A</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">PC</td>
			<td style="width:148px;">Dell</td>
			<td style="width:144px;">Optiplex 990</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">pCLAMP 10.3 Voltage Clamp Software</td>
			<td style="width:148px;">Molecular Devices, LLC</td>
			<td style="width:144px;">pCLAMP10.3</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:149px;">TMC Vibration Control TableTop Platform</td>
			<td style="width:148px;">TMC</td>
			<td style="width:144px;">64 SERIES</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">TMC Vibration Control Air Table</td>
			<td style="width:148px;">TMC</td>
			<td style="width:144px;"><a name="RANGE!C10">20 Series&#160;</a></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">V1/I Electrode Data Collector</td>
			<td style="width:148px;">Dagan</td>
			<td style="width:144px;">part of CA-1B</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">MX10L Micromanipulator</td>
			<td style="width:148px;">Siskiyou</td>
			<td style="width:144px;">MX10L</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:149px;">Bath/Guard (I/V) Headstage (with appropriate connectors)</td>
			<td style="width:148px;">Dagan</td>
			<td style="width:144px;">part of CA-1B</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Microscope</td>
			<td style="width:148px;">Omano</td>
			<td style="width:144px;">OM2300S-JW11</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:149px;">Temperature Control Bath</td>
			<td style="width:148px;">Custom or Dagan</td>
			<td style="width:144px;">Custom or HE-204C</td>
			<td style="width:285px;">Custom chamber made from materials from Cool Polymers (D-series). Dagan also provides a prefeabricated stage (HE-204C).</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Custom AgCl Pellet Container</td>
			<td style="width:148px;">Custom</td>
			<td style="width:144px;">Custom</td>
			<td style="width:285px;">Custom machined</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Ag/AgCl electrode, pellet, 2.0 mm</td>
			<td style="width:148px;">Warner</td>
			<td style="width:144px;">E-206</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">External Oocyte Bath</td>
			<td style="width:148px;">Custom or Dagan</td>
			<td style="width:144px;">Custom or CC-1-T-LB</td>
			<td style="width:285px;">Custom machined or purchased from Dagan</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Internal Oocyte Bath</td>
			<td style="width:148px;">Custom or Dagan</td>
			<td style="width:144px;">Custom or CC-TG-ND</td>
			<td style="width:285px;">Custom machined or purchased from Dagan</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:149px;">Capillaries for Agar Bridges and Pulled Electrodes</td>
			<td style="width:148px;">Warner</td>
			<td style="width:144px;">G150T-4</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:149px;">Rotatable Mounts for the Microscope, Micromanipulator, and Bath</td>
			<td style="width:148px;">Siskiyou</td>
			<td style="width:144px;">SD-1280P</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Fiber-Lite</td>
			<td style="width:148px;">Dolan-Jenner</td>
			<td style="width:144px;">LMI-600</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Regular Bleach</td>
			<td style="width:148px;">Clorox</td>
			<td style="width:144px;">470174-764</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Xenopus laevis Oocytes</td>
			<td style="width:148px;">Nasco</td>
			<td style="width:144px;">LM535M (sexually mature females)</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:149px;">90 Na+ External Solution</td>
			<td style="width:148px;">See Solutions sheet</td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:149px;">10 Na+ Internal Solution</td>
			<td style="width:148px;">See Solutions sheet</td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">3 M KCL</td>
			<td style="width:148px;">See Solutions sheet</td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Saponin</td>
			<td style="width:148px;">Sigma-Aldrich</td>
			<td style="width:144px;">47036</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">NMDG Storage Solution</td>
			<td style="width:148px;">See Solutions sheet</td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">5mL transfer pipets</td>
			<td style="width:148px;">SciMart</td>
			<td style="width:144px;">GS-52</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:149px;">Modified KCl electrode injector</td>
			<td style="width:148px;">BD</td>
			<td style="width:144px;">309659</td>
			<td style="width:285px;">Plastic syringe tip melted to allow for injection of solution into electrodes. Alternatively, a Microfil by WPI can be purchased.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Microvaccum</td>
			<td style="width:148px;">Custom</td>
			<td style="width:144px;">Custom</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">Forceps</td>
			<td style="width:148px;">VWR</td>
			<td style="width:144px;">63040-458</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Oocyte Handling Tools (Pipette Pump)</td>
			<td style="width:148px;">VWR</td>
			<td style="width:144px;">53502-222</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Deionized Water Squirt Bottle</td>
			<td style="width:148px;">VWR</td>
			<td style="width:144px;">16649-911</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Vaseline Petroleum Jelly</td>
			<td style="width:148px;">Fisher Scientific</td>
			<td style="width:144px;">19-086-291&#160;</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;"></td>
			<td style="width:148px;"></td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:149px;">Additional Materials Required for VCF Recordings:</td>
			<td style="width:148px;"></td>
			<td style="width:144px;"></td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:149px;">VCF Microscope</td>
			<td style="width:148px;">Nikon</td>
			<td style="width:144px;">Eclipse FN1</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Nikon CFI APO 40XW NIR Objective</td>
			<td style="width:148px;">Nikon</td>
			<td style="width:144px;">N40X-NIR</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:149px;">X-Y Translator System for Fixed-Stage Upright Microscopes</td>
			<td style="width:148px;">Sutter Instruments</td>
			<td style="width:144px;">MT500-586</td>
			<td style="width:285px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">External VCF Oocyte Bath</td>
			<td style="width:148px;">Custom</td>
			<td style="width:144px;"></td>
			<td style="width:285px;">Custom machined. The chamber dimensions are 2.7 x 1.9 x 0.4 cm.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:149px;">Internal VCF Oocyte Bath</td>
			<td style="width:148px;">Custom</td>
			<td style="width:144px;"></td>
			<td style="width:285px;">Custom machined. The chamber dimensions are 1.6 x 1.6 x 0.4 cm.</td>
		</tr>
		<tr height="126">
			<td height="126" style="height:126px;width:149px;">Modified Temperature Control Bath</td>
			<td style="width:148px;">Custom</td>
			<td style="width:144px;"></td>
			<td style="width:285px;">Custom chamber made from materials from Cool Polymers (D-series). The chamber dimensions of the modified temperature controller bath are 2.7 x 1.9 x 0.3 cm for the horizontal chamber, and 1 x 2.5 x 0.5 cm for the vertical chamber.</td>
		</tr>
	</tbody>
</table>

the xenopus oocyte cut-open vaseline gap voltage-clamp technique with fluorometry

A vaselina oócito lacuna cut-aberto (COVG) técnica braçadeira de tensão permite a análise das propriedades eletrofisiológicas e cinéticos de canais iônicos heterólogas em oócitos. Gravações do setup cut-aberto são particularmente úteis para a resolução de correntes de baixa magnitude gating, rápida ativação corrente iônica e desativação. As principais vantagens sobre a tensão de dois eléctrodos de aperto (TEVC) técnica incluem o aumento da velocidade de fixação, uma melhor relação sinal-ruído, e a capacidade de modular o intracelular e meio extracelular. Aqui, nós empregamos o canal de sódio cardíaco humano (HNA V 1.5), expressa em oócitos de Xenopus, para demonstrar a configuração cut-aberto e protocolo, bem como as modificações que são necessárias para adicionar capacidade de fluorometria braçadeira de tensão. As propriedades dos canais iônicos de ativação rápida, como HNA V 1.5, não pode ser totalmente resolvido em temperatura ambiente usando TEVC, em which, a totalidade da membrana do oócito é apertado, tornando difícil o controlo da tensão. No entanto, na técnica de corte-aberto, o isolamento de apenas uma pequena porção da membrana celular permite a fixação rápida necessária para registar com precisão cinética rápida evitando canal degradado associado com técnicas de fixação de membranas. Em conjunção com a técnica COVG, cinética do canal de iões e propriedades electrofisiológicas pode ser ainda analisada utilizando fluorimetria fixador de tensão, onde o movimento é controlado por meio da proteína de cisteína de conjugação de fluoróforos extracelularmente aplicadas, a inserção de proteínas fluorescentes codificados geneticamente, ou a incorporação de aminoácidos não naturais na região de interesse 1. Esta informação adicional produz informação cinética sobre rearranjos conformacionais dependentes de voltagem da proteína através de alterações no microambiente em torno da molécula fluorescente.

A Figura 4 mostra a variação na permeabilidade do oócito como uma solução de saponina é aplicada à parte inferior do oócito. Figura 5 mostra a taxa de troca da solução intracelular por difusão seguinte permeabilização saponina. 20-40 min são necessárias para chegar a um estado de equilíbrio 2,18. A Figura 6A mostra vestígios gerados a partir do protocolo de gravação. A figura mostra as correntes iónicas (após subtracção P/-8 vazamento), em resposta ao protocolo de voltagem (inset). Cada traço na figura representa uma tensão aplicada diferente. Os traços com mais lentos cinética representam os menores potenciais em que o canal de sódio pode abrir. Tipicamente, usando os métodos tradicionais, é difícil manter o controlo de voltagem para estas potenciais mais baixos, porque a corrente interna despolariza a membrana. Esta despolarização por sua vez ativa mais canais criando um loop de feedback positivo<html> . A velocidade de fixação melhorada da técnica de corte-aberto permite o controle de tensão necessária para a gravação do canal, mesmo a esses potenciais difíceis. A Figura 6B mostra a curva de corrente / tensão, o qual foi gerado a partir de vestígios na Figura 6A. Sem o controle de tensão observado acima, a corrente de pico nas primeiras potenciais (~ -60 mV) seria sobre-estimado. Isso impediria descrição precisa da relação corrente-tensão. A Figura 7 mostra um exemplo dos resultados de fluorometria grampo de voltagem para um ovócito. Os sinais de fluorescência foram registados a partir de um ovócito marcado com MTS-TAMRA a uma cisteína inserido na posição 805 no domínio DII do canal de sódio cardíaco humano Na V 1.5. &quot;width =&quot; _upload/51040/51040fig5.jpg 500px &quot;/&gt; Figura 5. Cinética de citoplasmática Na + Concentração mudança por difusão. A taxa de equilíbrio solução interna foi avaliada através da aplicação de 90 mM de Na + para ambos os lados interno e externo da célula e, em seguida, medir o potencial de inversão de Na + através da gravação de relações IV a cada 2 min. Se o meio interno foram perfeitamente substituídos, E rev seria 0 mV. Medições de tempo foram iniciados quando saponina permeabilizadas a membrana do oócito. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51040/51040fig5highres.jpg" target="_blank">Clique aqui para ver a imagem ampliada</a> . <img alt="Figura 6" fo:content-width="5in" fo:src="/files/ftp_upload/51040/51040fig6highres.jpg" src="/files/ftp_upload/51040/51040fig6.jpg" width="500px" /> Figura 6. Tipo Selvagem Na v 1.5Os resultados dos canais de sódio de Cut-Open de tensão de aperto. (A) Traços de gravado atual de diferentes tensões de estímulos a partir de um potencial de realização de -80 mV até -120 mV para 100 ms, o pulso de teste (-120 mV a +40 mV em incrementos de 10 mV) para 200 milissegundos e, finalmente, a repolarização -120 mV. (B) A curva IV, que representa a tensão de dependência do pico de corrente no painel A. Aqui, a corrente de pico para pulsos até 60 mV é mostrada. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51040/51040fig6highres.jpg" target="_blank">Clique aqui para ver a imagem ampliada</a> . <img alt="Figura 7" fo:content-width="5in" fo:src="/files/ftp_upload/51040/51040fig7highres.jpg" src="/files/ftp_upload/51040/51040fig7.jpg" width="500px" /> Figura 7. Na v 1.5 Sódio canal de tensão da braçadeira Fluorometria Recordings. (A) Ionic correntes registradas a partir de um óvulorotulado com MTS-TAMRA a uma cisteína inserido na posição 805 no domínio DII-S4 do canal de sódio cardíaco humano Na V 1.5. Impulsos de tensão que vão desde -170 mV a 70 mV foram aplicadas em intervalos de 20 mV para uma duração de 20 ms depois de uma pré-pulso de -120 mV. (B) Os sinais de fluorescência associados. Cada outro traço de fluorescência é omitida para maior clareza. Af / F representa a mudança relativa da intensidade de fluorescência induzida pelo pulso de voltagem. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/51040/51040fig7highres.jpg" target="_blank">Clique aqui para ver a imagem ampliada</a> .

Watch this Scientific Journal Video about The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry at JoVE.com

The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

A abordagem lacuna vaselina cut-aberto é usado para obter baixos gravações de ruídos de correntes iônicas e gating de canais iônicos dependentes de voltagem expressos em oócitos de Xenopus com alta resolução de cinética de canais rápidos. Com modificações menores, fixador de tensão fluorometria pode ser acoplado com o protocolo do oócito corte aberto.

O<em&gt; Xenopus</em&gt; Oocyte Cut-aberto vaselina Gap Técnica Voltage-clamp Com Fluorometria

The cut-open oocyte Vaseline gap (COVG) voltage clamp technique allows for analysis of electrophysiological and kinetic properties of heterologous ion ...

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The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

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18.3K visualizações.  Washington University in St. Louis.  A abordagem lacuna vaselina cut-aberto é usado para obter baixos gravações de ruídos de correntes iônicas e gating de canais iônicos dependentes de voltagem expressos em oócitos de Xenopus com alta resolução de cinética de canais rápidos. Com modificações menores, fixador de tensão fluorometria pode ser acoplado com o protocolo do oócito corte aberto. 

Vídeo: The Xenopus Oocyte Cut-open Vaseline Gap Voltage-clamp Technique With Fluorometry

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 ...

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 ...

Mouse Oocyte Microinjection, Maturation and Ploidy Assessment

Mistakes in chromosome segregation lead to aneuploid cells. In somatic cells, aneuploidy is associated with cancer but in gametes, aneuploidy leads to infertility, miscarriages or developmental disorders like Down syndrome. Haploid gametes form through species-specific developmental programs that are coupled to meiosis. The first meiotic division (MI) is unique to meiosis because sister chromatids remain attached while homologous chromosomes are segregated. For reasons not fully understood, this reductional division is prone to errors and is more commonly the source of aneuploidy than errors in meiosis II (MII) or than errors in male meiosis 1,2. 
In mammals, oocytes arrest at prophase of MI with a large, intact germinal vesicle (GV; nucleus) and only resume meiosis when they receive ovulatory cues. Once meiosis resumes, oocytes complete MI and undergo an asymmetric cell division, arresting again at metaphase of MII. Eggs will not complete MII until they are fertilized by sperm. Oocytes also can undergo meiotic maturation using established in vitro culture conditions 3. Because generation of transgenic and gene-targeted mouse mutants is costly and can take long periods of time, manipulation of female gametes in vitro is a more economical and time-saving strategy. 
Here, we describe methods to isolate prophase-arrested oocytes from mice and for microinjection. Any material of choice may be introduced into the oocyte, but because meiotically-competent oocytes are transcriptionally silent 4,5 cRNA, and not DNA, must be injected for ectopic expression studies. To assess ploidy, we describe our conditions for in vitro maturation of oocytes to MII eggs. Historically, chromosome-spreading techniques are used for counting chromosome number 6. This method is technically challenging and is limited to only identifying hyperploidies. Here, we describe a method to determine hypo-and hyperploidies using intact eggs 7-8. This method uses monastrol, a kinesin-5 inhibitor, that collapses the bipolar spindle into a monopolar spindle 9 thus separating chromosomes such that individual kinetochores can readily be detected and counted by using an anti-CREST autoimmune serum. Because this method is performed in intact eggs, chromosomes are not lost due to operator error.

Oocytes are prone to aneuploidy due to errors in chromosome segregation during meiotic maturation. Aneuploid eggs can cause infertility, miscarriages or developmental disorders like Down syndrome. Here, we describe methods to introduce materials of choice into oocytes and methods to study meiotic maturation and assess ploidy.

Avaliação do mouse microinjeção de oócitos, maturação e ploidia

Mistakes in chromosome segregation lead to aneuploid cells.  In somatic cells, aneuploidy is associated with cancer but in gametes, aneuploidy leads to ...

Single Oocyte Bisulfite Mutagenesis

Epigenetics encompasses all heritable and reversible modifications to chromatin that alter gene accessibility, and thus are the primary mechanisms for regulating gene transcription1. DNA methylation is an epigenetic modification that acts predominantly as a repressive mark. Through the covalent addition of a methyl group onto cytosines in CpG dinucleotides, it can recruit additional repressive proteins and histone modifications to initiate processes involved in condensing chromatin and silencing genes2. DNA methylation is essential for normal development as it plays a critical role in developmental programming, cell differentiation, repression of retroviral elements, X-chromosome inactivation and genomic imprinting.
One of the most powerful methods for DNA methylation analysis is bisulfite mutagenesis. Sodium bisulfite is a DNA mutagen that deaminates cytosines into uracils. Following PCR amplification and sequencing, these conversion events are detected as thymines. Methylated cytosines are protected from deamination and thus remain as cytosines, enabling identification of DNA methylation at the individual nucleotide level3. Development of the bisulfite mutagenesis assay has advanced from those originally reported4-6 towards ones that are more sensitive and reproducible7. One key advancement was embedding smaller amounts of DNA in an agarose bead, thereby protecting DNA from the harsh bisulfite treatment8. This enabled methylation analysis to be performed on pools of oocytes and blastocyst-stage embryos9. The most sophisticated bisulfite mutagenesis protocol to date is for individual blastocyst-stage embryos10. However, since blastocysts have on average 64 cells (containing 120-720 pg of genomic DNA), this method is not efficacious for methylation studies on individual oocytes or cleavage-stage embryos.
Taking clues from agarose embedding of minute DNA amounts including oocytes11, here we present a method whereby oocytes are directly embedded in an agarose and lysis solution bead immediately following retrieval and removal of the zona pellucida from the oocyte. This enables us to bypass the two main challenges of single oocyte bisulfite mutagenesis: protecting a minute amount of DNA from degradation, and subsequent loss during the numerous protocol steps. Importantly, as data are obtained from single oocytes, the issue of PCR bias within pools is eliminated. Furthermore, inadvertent cumulus cell contamination is detectable by this method since any sample with more than one methylation pattern may be excluded from analysis12. This protocol provides an improved method for successful and reproducible analyses of DNA methylation at the single-cell level and is ideally suited for individual oocytes as well as cleavage-stage embryos.

Bisulfite mutagenesis is the gold standard for analyzing DNA methylation. Our modified protocol allows for DNA methylation analysis at the single-cell level and was specifically designed for individual oocytes. It can also be used for cleavage-stage embryos.

Mutagênese Bissulfito Único de ovócitos

Epigenetics encompasses all heritable and reversible modifications to chromatin that alter gene accessibility, and thus are the primary mechanisms for ...

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.

Estudo da Checkpoint Dano ao DNA usando<em&gt; Xenopus</em&gt; Os extratos de ovos

On a daily basis, cells are subjected to a variety of endogenous and environmental insults. To combat these insults, cells have evolved DNA damage ...

Measuring Intracellular Ca2+ Changes in Human Sperm using Four Techniques: Conventional Fluorometry, Stopped Flow Fluorometry, Flow Cytometry and Single Cell Imaging

Spermatozoa are male reproductive cells especially designed to reach, recognize and fuse with the egg. To perform these tasks, sperm cells must be prepared to face a constantly changing environment and to overcome several physical barriers. Being in essence transcriptionally and translationally silent, these motile cells rely profoundly on diverse signaling mechanisms to orient themselves and swim in a directed fashion, and to contend with challenging environmental conditions during their journey to find the egg. In particular, Ca2+-mediated signaling is pivotal for several sperm functions: activation of motility, capacitation (a complex process that prepares sperm for the acrosome reaction) and the acrosome reaction (an exocytotic event that allows sperm-egg fusion). The use of fluorescent dyes to track intracellular fluctuations of this ion is of remarkable importance due to their ease of application, sensitivity, and versatility of detection. Using one single dye-loading protocol we utilize four different fluorometric techniques to monitor sperm Ca2+ dynamics. Each technique provides distinct information that enables spatial and/or temporal resolution, generating data both at single cell and cell population levels.

Measuring Intracellular Ca2+ Changes in Human Sperm using Four Techniques: Conventional Fluorometry, Stopped Flow Fluorometry, Flow Cytometry and Single Cell Imaging

Intracellular Ca2+ dynamics are very important in sperm physiology and Ca2+-sensitive fluorescent dyes constitute a versatile tool to study them. Population experiments (fluorometry and stopped flow fluorometry) and single cell experiments (flow cytometry and single cell imaging) are used to track spatio-temporal [Ca2+] changes in human sperm cells.

Medindo intracelular de Ca<sup&gt; 2 +</sup&gt; Mudanças no esperma humano, utilizando quatro técnicas: fluorometria convencional, Parado Fluorometria fluxo, citometria de fluxo e única célula de imagem

Spermatozoa  are male reproductive cells especially designed to reach, recognize and fuse  with the egg. To perform these tasks, sperm cells must be ...

Facial Transplants in Xenopus laevis Embryos

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. To identify where signaling pathways and tissues act during patterning of the developing face, a 'face transplant' technique has been developed in embryos of the frog Xenopus laevis. A region of presumptive facial tissue (the "Extreme Anterior Domain" (EAD)) is removed from a donor embryo at tailbud stage, and transplanted to a host embryo of the same stage, from which the equivalent region has been removed. This can be used to generate a chimeric face where the host or donor tissue has a loss or gain of function in a gene, and/or includes a lineage label. After healing, the outcome of development is monitored, and indicates roles of the signaling pathway within the donor or surrounding host tissues. Xenopus is a valuable model for face development, as the facial region is large and readily accessible for micromanipulation. Many embryos can be assayed, over a short time period since development occurs rapidly. Findings in the frog are relevant to human development, since craniofacial processes appear conserved between Xenopus and mammals.

Facial Transplants in Xenopus laevis Embryos

A technique for transplanting "Extreme Anterior Domain" facial tissue between Xenopus laevis embryos has been developed. Tissue can be moved from one gene expression background into another, allowing the study of local requirements for craniofacial development and for signaling interactions between facial regions.

Transplantes faciais em<em&gt; Xenopus laevis</em&gt; Os embriões

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. ...

Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4

TRPV4 (Transient Receptor Potentials, vanilloid family, type 4) is widely expressed in vertebrate tissues and is activated by several stimuli, including by mechanical forces. Certain TRPV4 mutations cause complex hereditary bone or neuronal pathologies in human. Wild-type or mutant TRPV4 transgenes are commonly expressed in cultured mammalian cells and examined by Fura-2 fluorometry and by electrodes. In terms of the mechanism of mechanosensitivity and the molecular bases of the diseases, the current literature is confusing and controversial. To complement existing methods, we describe two additional methods to examine the molecular properties of TRPV4. (1) Rat TRPV4 and an aequorin transgene are transformed into budding yeast. A hypo-osmtic shock of the transformant population yields a luminometric signal due to the combination of aequorin with Ca2+, released through the TRPV4 channel. Here TRPV4 is isolated from its usual mammalian partner proteins and reveals its own mechanosensitivity. (2) cRNA of TRPV4 is injected into Xenopus oocytes. After a suitable period of incubation, the macroscopic TRPV4 current is examined with a two-electrode voltage clamp. The current rise upon removal of inert osmoticum from the oocyte bath is indicative of mechanosensitivity. The microAmpere (10-6 to 10-4 A) currents from oocytes are much larger than the subnano- to nanoAmpere (10-10 to 10-9 A) currents from cultured cells, yielding clearer quantifications and more confident assessments. Microscopic currents reflecting the activities of individual channel proteins can also be directly registered under a patch clamp, in on-cell or excised mode. The same oocyte provides multiple patch samples, allowing better data replication. Suctions applied to the patches can activate TRPV4 to directly assess mechanosensitivity. These methods should also be useful in the study of other types of TRP channels.

Yeast Luminometric and Xenopus Oocyte Electrophysiological Examinations of the Molecular Mechanosensitivity of TRPV4

To complement commonly used methods to study TRPV4&#8217;s, two methods are described: Its mechanosensitivity can be studied by Ca2+-aequorin luminometry in transgenic yeast upon hypo-osmotic challenge. It can also be examined in TRPV4-RNA injected Xenopus oocytes by whole-cell two-electrode voltage clamp or patch clamp in on-cell or excised mode.

Luminométricos levedura e<em&gt; Xenopus</em&gt; ovócitos eletrofisiológicos Exames do mecanosensibilidade Molecular de TRPV4

TRPV4 (Transient Receptor Potentials, vanilloid family, type 4) is widely expressed in vertebrate tissues and is activated by several stimuli, including ...

Xenopus laevis as a Model to Identify Translation Impairment

Protein synthesis is a fundamental process to gene expression impacting diverse biological processes notably adaptation to environmental conditions. The initiation step, which involves the assembly of the ribosomal subunits at the mRNA initiation codon, involved initiation factor including eIF4G1. Defects in this rate limiting step of translation are linked to diverse disorders. To study the potential consequences of such deregulations, Xenopus laevis oocytes constitute an attractive model with high degrees of conservation of essential cellular and molecular mechanisms with human. In addition, during meiotic maturation, oocytes are transcriptionally repressed and all necessary proteins are translated from preexisting, maternally derived mRNAs. This inexpensive model enables exogenous mRNA to become perfectly integrated with an effective translation. Here is described a protocol for assessing translation with a factor of interest (here eIF4G1) using stored maternal mRNA that are the first to be polyadenylated and translated during oocyte maturation as a physiological readout. At first, mRNA synthetized by in vitro transcription of plasmids of interest (here eIF4G1) are injected in oocytes and kinetics of oocyte maturation by Germinal Vesicle Breakdown detection is determined. The studied maternal mRNA target is the serine/threonine-protein-kinase mos. Its polyadenylation and its subsequent translation are investigated together with the expression and phosphorylation of proteins of the mos signaling cascade involved in oocyte maturation. Variations of the current protocol to put forward translational defects are also proposed to emphasize its general applicability. In light of emerging evidence that aberrant protein synthesis may be involved in the pathogenesis of neurological disorders, such a model provides the opportunity to easily assess this impairment and identify new targets.

Xenopus laevis as a Model to Identify Translation Impairment

Protein synthesis control occurs mainly at the translation initiation step, deficiencies in which are linked to diverse disorders. To better understand their etiology, we described here a protocol using Xenopus laevis oocytes assessing the translation of mos transcript in the presence of a mutant of translation initiation factor eIF4G1.

Xenopus laevis como um modelo para identificar Tradução Impairment

Protein synthesis is a fundamental process to gene expression impacting diverse biological processes notably adaptation to environmental conditions. The ...