PA é um beneficiário de uma bolsa &quot;Pierre Durand&quot; pela Faculdade de Medicina da Universidade de Laval. Este trabalho foi apoiado pelas Ciências Naturais e Engenharia Research Council of Canada (MOP-CG095386) para RM O fraccionamento polysome foi adquirida através de uma Fundação Canadense para concessão inovação (MOP-GF091050) para RMR M tem um novo prêmio salário investigador CIHR. Somos gratos aos drs. E. Khandjian, I. Gallouzi, S. Di-Marco e A. Cammas para conselhos úteis.

O protocolo a seguir as orientações aprovado pelo Conselho de Revisão Ética de Laval. 1. Preparação de culturas de células e Manipulação do cérebro <ol><li> As células de mamíferos e de Drosophila <ol><li> Crescer HeLa células de câncer cervical e células embrionárias Schneider Drosophila como recomendado pela American Type Culture Collection. Trabalhar com células em uma passagem baixa. </li><li> Células da placa, a fim de atingir 80% de confluência no dia da experiência. Para melhores resultados, utilizar ~ 12 x 10 6 de células para cada condição experimental. Antes de fazer extratos para análise polysome, estimular a tradução através da adição de meio completo fresco por pelo menos 90 min. </li></ol></li><li> Isolamento Cérebro: Isolar cérebros de camundongos com idade entre 9 e 16 dias após o nascimento. A eutanásia envolve inalação de CO 2 após anestesia e deslocamento cervical. Após o sacrifício, isolar todo o cérebro e quer lugar it a -80 ° C ou transferi-lo diretamente no frio PBS 1X, para uso imediato. </li></ol> 2. Preparação do Sistema de Gradiente de Densidade Fracionamento <ol><li> Lavar o sistema de tubagem com 0,1% de SDS durante 5 minutos. </li><li> Lavar o sistema de tubos com 70% de etanol durante 5 minutos, em seguida, com solução RNaseZAP durante 5 min antes de lavá-la com água DEPC. </li><li> Bomba de ar, a fim de secar o sistema de tubagem do aparelho. </li></ol> 3. Preparação dos gradientes de sacarose <ol><li> Adicione 15% e 55% de soluções de sacarose em 20 mM Tris-HCl pH 7,4, 1,25 mM de MgCl2, 150 mM de NaCl, e 1 mM de DTT. </li><li> Gerar a 15-55% de gradiente linear de sacarose utilizando um Isco Modelo 160 gradiente anterior, conforme descrito nas instruções do fabricante. No entanto, é importante para controlar bem a velocidade de TRIS bomba peristáltica, a fim de evitar a criação de bolhas ou de turbulências nos gradientes. Manter os gradientes a 4 ° C até à sua utilização. </li><li> Durante o tempo em que o programa de formador de gradiente está em execução, esfriar a ultracentrífuga a 4 ° C. </li></ol> 4. Preparação de celular e cérebro do rato Extratos <ol><li> Preparação de Extratos celulares <ol><li> Coloque placa (s) em células de gelo e lavagem 3x com PBS frio 1X. </li><li> Células colheita (~ 12 x 10 6) em 1 ml de tampão de lise (20 mM Tris-HCl, pH 7,4, 1,25 mM de MgCl2, 150 mM de NaCl, 1 mM de DTT, 1% Nonidet P40, 5 U de inibidor / ml de RNase, suplementado com mini tabletes completos inibidor de protease cocktail livre de EDTA), transferi-los para um tubo de Eppendorf, e misture bem, passando-os 15x através de uma seringa 1cc U100 Insulina 28 G 1/2. Deixe o ligado de células repousar em gelo durante 15 min. </li><li> Coloque algumas gotas de lisado de células numa lâmina de avaliar a lise celular por meio da observação de um microscópio de contraste de fase com uma objectiva 10X. Somente os núcleos devem estar visíveis e sem membranas celulares devem ser atestando visível para a lise celular. Como controle, observecélulas não lisadas. </li><li> Clarificar o ligado celular por centrifugação a 11.000 xg durante 20 min a 4 ° C e manter o lisado solúvel contendo os polirribossomas. </li></ol></li><li> Preparação do cérebro do rato Extratos <ol><li> Homogeneizar o cérebro inteiro isolado (~ 500 mg) por 10 movimentos de um homogeneizador Dounce gelado com 2 ml de tampão de lise e clarificação do homogenado por centrifugação a 11.000 xg durante 15 min a 4 ° C. </li><li> Carrega-se o sobrenadante resultante sobre uma almofada de sacarose a 50% e prosseguir com a sedimentação durante 2 h a 200.000 x g usando um rotor de ultracentrífuga TH-641 a 4 ° C. </li><li> Ressuspender o sedimento translúcido contendo os polirribossomas em 1 ml de tampão de lise e misturar bem por pipetagem para cima e para baixo. Deixe o resto suspensão sobre o gelo por 30 minutos antes de carregar em gradientes. </li></ol></li></ol> 5. Carregando os extratos em sacarose gradientes e Ultracentrifugação <ol><li> Medir a concentraçãode ARN presente no extracto citoplasmático utilizando um espectrofotómetro. Devagar e com cuidado carregar ~ 20 unidades de DO 260 do extracto sobre o gradiente de sacarose de 15% a 55%. Certifique-se de que não é de 2-3 mm de espaço disponível na superfície do tubo, para evitar transbordamento dos tubos, durante a centrifugação. </li><li> Centrifugar os gradientes utilizando uma ultra-centrifugadora durante 2 h 30 min a 230.000 x g usando um rotor de ultracentrífuga TH-641 a 4 ° C. Quando termina a centrifugação, remover os tubos e colocá-los no gelo com cuidado para não perturbar os gradientes. </li></ol> 6. Fracionamento de extratos citoplasmáticos para polissomos Profiling <ol><li> Coloque gradientes de sacarose no Sistema Automatizado de fraccionamento de densidade e prosseguir com fraccionamento automatizado e recolha de fracções (0,5 ml cada), tal como descrito pelo fabricante. </li><li> Recolhe cada fracção (~ 500 mL) em tubos de Eppendorf individuais, com monitorização contínua da absorvância a 254 nm. Em PARALLel da operação de fracionamento de gradiente, o perfil polyribosomal estará editando no papel gráfico. Como alternativa, use uma unidade de aquisição de dados conectado ao registrador gráfico para ter uma aquisição eletrônica do perfil polysome. </li><li> No final de cada corrida, transferir Eppendorfs coletadas em gelo seco. Neste momento, qualquer loja recolhidas fracções a -80 ° C ou precipitar directamente complexos de ARN-proteína, como se segue. </li></ol> 7. Extração de proteínas e análise <ol><li> Para cada fracção recolhida do gradiente de sacarose, adicionar 2 volumes de etanol a 100% frio e deixar complexos de ARN-proteína precipitar a -20 ° C durante a noite. </li><li> Centrifugar cada precipitado de ARN-proteína a 11.000 xg durante 20 min a 4 ° C, em seguida, lava-se com etanol a 70%. Seco e ressuspender o precipitado em tampão de amostra de SDS-PAGE antes de prosseguir com a Western blot usando anticorpos específicos (ver Figura 2). </li></ol> 8. Extração de RNA e Análise <ol><li> Precipitar complexos RNA-proteína como na secção 7.1. Ressuspender cada precipitado de ARN-proteína no tampão de lise contendo 0,1% de SDS. Digerir o componente proteína do precipitado com 2 mg / ml de proteinase K, durante 30 minutos num banho de água a 55 C °. </li><li> Extrair os componentes de ARN precipitado por adição de 1 volume de &quot;fenol: clorofórmio&quot;, 2 volumes de clorofórmio, e 0,1 volume de NaOAc 2 M pH 4, e centrifugação a 10.000 xg, a 4 ° C durante 20 min. O precipitado de ARN a partir da fase aquosa resultante de cada amostra durante a noite a -20 ° C pela adição de um volume de isopropanol e de 0,2 mg / mL de glicogénio. Girar-se o precipitado durante 1 hora a 10.000 x g a 4 ° C. Lavar o sedimento de ARN com etanol a 70% frio. </li><li> Ressuspender o sedimento de ARN em um pequeno volume de ARNase isenta de água. Avaliar a quantidade e qualidade de RNA utilizando o espectrofotómetro. </li></ol>

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A análise do perfil de polissoma em gradientes de sacarose permite a medição da iniciação da tradução através da análise da densidade de polissomas isolados a partir de células ou tecidos de 9,11-14. Esta técnica é a melhor (se não o único) abordagem para medir a iniciação da tradução in vivo. Ele é utilizado para monitorizar o estado de crescimento de células de translação durante o ciclo de célula 15, e para avaliar os efeitos de vários tipos de stress, incluindo ...

As células eucarióticas encontrar constantemente uma gama de condições de estresse fisiológicos e ambientais nocivos que exigem uma resposta celular adaptativa rápida. Resposta ao estresse celular envolve um equilíbrio preciso entre anti-sobrevivência e pró-sobrevivência fatores atuando. Perturbar este equilíbrio pode ter consequências irreversíveis que levam ao desenvolvimento de patologias humanas, como câncer e doenças neurodegenerativas. Durante o primeiro passo da resposta ao stress, as células de activar as vias pró-sobrevivência que envolvem o controlo coordenado de alterações na expressão do gene ao nível da tradução do mRNA. tradução do mRNA em eucariotos é um processo celular complexo que envolve interações coordenadas entre os fatores de iniciação da tradução (EIFS), proteínas de ligação de RNA específico (RBDs) e moléculas de RNA 1. tradução do mRNA é dividido em três fases distintas: iniciação, alongamento e terminação. Embora todas as três fases estão sujeitos a regulamenmecanismos reguladoras nacionais, os mecanismos de controlo da tradução como alvo principalmente na fase de iniciação da tradução, que assim constitui o passo limitante da taxa de síntese de proteína 2. De iniciação da tradução é um processo altamente ordenadas que começa com a formação da eIF2a.GTP.Met-ARNt eu Met complexo ternário e sua subsequente ligação à subunidade 40S do ribossoma, levando à formação do complexo de pré-iniciação. O próximo passo é o recrutamento do complexo de pré-iniciação de ARNm, que envolve a actividade de factores de iniciação da tradução, tais como eIF4F e eIF3. O complexo de pré-iniciação 48S assim formado sofre alterações conformacionais específicos que permitem que esta maquinaria para iniciar a digitalização da região 5 &#39;não traduzida do mRNA, até que reconhece o codão de iniciação agosto A maioria dos fatores de iniciação da tradução são então liberados e 60 subunidades são recrutados para formar um ribossomo 80S complexo competente para a tradução, umat que começa síntese protéica ponto (Figura 1). Mais do que uma 80S monosome pode ser traduzindo o mesmo mRNA de cada vez produzindo assim chamados polissomas (ou polirribossomas). A densidade de polissomas num ARNm reflecte a iniciação, elongação e taxas de terminação e, assim, é uma medida da traductibilidade de um transcrito particular. No entanto, em polissoma perfil é utilizado principalmente para avaliar alterações na tradução do mRNA na etapa de iniciação. Aqui utilizámos um inibidor de proteassoma, como inibidor de iniciação da tradução. O tratamento de células cancerosas com esta droga induz uma resposta ao estresse caracteriza-se pela ativação do estresse chamado HRI quinase que fosforila o fator de iniciação da tradução eIF2a 3. A fosforilação de eIF2a é um dos principais eventos que levam à inibição da iniciação da tradução, em células de mamíferos 4.

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			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
			<td height="21" style="height:21px;width:279px;">Cells</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:279px;">HeLa cervical cancer cells</td>
			<td style="width:311px;">American Type Culture Collection (Manassas, VA; ATCC)</td>
			<td>CCL-2</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:279px;">Schneider Drosophila embryonic cells</td>
			<td style="width:311px;">American Type Culture Collection (Manassas, VA; ATCC)</td>
			<td>CRL-1963</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Culture medium and Supplements</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Schneider&#8217;s Drosophila Medium</td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td>SO146-500ml</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">DMEM</td>
			<td>Life technologies</td>
			<td>11995-073</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">FBS</td>
			<td>Fisher Scientist Scientist</td>
			<td>SH30396-03</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">penicillin/streptomycin</td>
			<td>Life technologies</td>
			<td style="width:119px;">15140122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Sucrose solutions</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">D-Sucrose</td>
			<td>Fisher Scientist</td>
			<td>BP220-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Glycerol</td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td>49767</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Blue Bromophenol</td>
			<td>Fisher Scientist</td>
			<td>B3925</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Lysis buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Tris Hydrochloride</td>
			<td>Fisher Scientist</td>
			<td>BP153-500</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:279px;">MgCl2 </td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td style="width:119px;">M2670-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">NaCl</td>
			<td>Tekniscience</td>
			<td>3624-05</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">DTT</td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td>D 9779</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Nonidet P40 (Igepal CA-630 )</td>
			<td>MJS Biolynx</td>
			<td>19628</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">SDS</td>
			<td>Tekniscience</td>
			<td>4095-02</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:279px;">RNase inhibitor (RnaseOUT Recombinant Ribonuclease Inhibitor)</td>
			<td>Life technologies</td>
			<td>10777-019</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Antiproteases (complete, mini, EDTA free)</td>
			<td>Roche</td>
			<td>11,836,170,001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">RNA Extraction</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Proteinase K</td>
			<td>Life technologies</td>
			<td style="width:119px;">AM2542</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Phenol: Chloroforme</td>
			<td>Fisher Scientist</td>
			<td style="width:119px;">BP1754I-400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Chloroforme</td>
			<td style="width:311px;">Fisher Scientist</td>
			<td style="width:119px;">C298-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Glycogen</td>
			<td>Life technologies</td>
			<td>10814-010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Isopropanol</td>
			<td style="width:311px;">Acros organics</td>
			<td>327270010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Antibodies</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">anti-FMRP antibody</td>
			<td colspan="2" style="width:429px;">Fournier et al., Cancer Cell International, 2010</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">anti-Ribosomal Protein L28 antibody</td>
			<td style="width:311px;">Santa Cruz Biotechnology, Inc.</td>
			<td style="width:119px;">SC-50362</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Others</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Proteasome inhibitor : Bortezomib</td>
			<td style="width:311px;">LC Laboratories</td>
			<td style="width:119px;">B-1408</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">DEPC (Diethylpyrocarbonate)</td>
			<td style="width:311px;">Sigma-Aldrich</td>
			<td>D5758-25ml</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">RNaseZAP Solution</td>
			<td>Life technologies</td>
			<td style="width:119px;">AM9780</td>
			<td></td>
		</tr>
		<tr height="21">
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
			<td height="21" style="height:21px;width:279px;">Materials</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">T25 cell culture flask</td>
			<td style="width:311px;">Corning</td>
			<td style="width:119px;">430639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">1cc U100 Insulin Syringe 28 G1/2</td>
			<td>Fisher Scientist</td>
			<td>148291B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Tube ultra-centrifugation, PA, 12ml</td>
			<td>Fisher Scientist</td>
			<td>FSSP9763205</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Isco Model 160 gradient former</td>
			<td style="width:311px;">Teledyne Isco, Lincoln, NE, USA</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultracentrifuge Sorvall OTD Combi</td>
			<td style="width:311px;"></td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Thermo Scientific Sorvall Rotor TH-641</td>
			<td style="width:311px;">Thermo scientific</td>
			<td style="width:119px;">54295</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Automated Density Fractionation System</td>
			<td style="width:311px;">Teledyne Isco, Lincoln, NE, USA</td>
			<td style="width:119px;">67-9000-177</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Isco UA-6 UV-vis detector</td>
			<td style="width:311px;">Teledyne Isco, Lincoln, NE, USA</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:279px;">NanoDrop 2000 UV-Vis Spectrophotometer</td>
			<td style="width:311px;">Thermo scientific</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Ultracentrifuge C 5415</td>
			<td style="width:311px;">Eppendorf</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:279px;">Optical Microscope</td>
			<td style="width:311px;">Olympus CK2</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

analysis of translation initiation during stress conditions by polysome profiling

O controle preciso da tradução do mRNA é fundamental para a homeostase da célula eucariótica, em particular na resposta ao stress fisiológico e patológico. Alterações deste programa pode conduzir ao crescimento de células danificadas, uma indicação de desenvolvimento de cancro, ou a morte prematura das células, tal como visto nas doenças neurodegenerativas. Muito do que se conhece sobre a base molecular para o controlo da tradução foi obtido a partir de análise de polissoma usando um sistema de fraccionamento de gradiente de densidade. Esta técnica baseia-se na ultracentrifugação de extractos citoplasmáticos de um gradiente linear de sacarose. Uma vez que a rotação é completado, o sistema permite o fraccionamento e quantificação de zonas correspondentes a centrifugadas traduzindo diferente ribossomos populações, resultando, assim, em um perfil de polissoma. As alterações no perfil de polissoma são indicativos de alterações ou defeitos de iniciação da tradução que ocorrem em resposta a vários tipos de stress. Esta técnica também permite avaliar the papel de proteínas específicas no início da tradução e, para medir a atividade de translação de mRNAs específicos. Aqui descrevemos o nosso protocolo para realizar perfis de polissomas, a fim de avaliar a iniciação da tradução de células e de tecidos eucarióticos, em condições de crescimento normais ou de stress.

Como referido acima, polysome perfil permite a análise de mudanças de iniciação da tradução em condições de estresse. Figura 1 é uma visão simplificada de iniciação da tradução, que, conforme descrito anteriormente é um processo de várias etapas que envolvem um conjunto ordenado de complexos de iniciação da tradução. Em condições normais de crescimento, os complexos de iniciação da tradução são convertidos em polirribossomos cuja detecção por perfil polysome atestam para uma...

Watch this Scientific Journal Video about Analysis of Translation Initiation During Stress Conditions by Polysome Profiling at JoVE.com

Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Aqui, descrevemos um método para analisar mudanças na iniciação da tradução do mRNA de células eucarióticas em resposta a condições de estresse. Este método baseia-se na separação de velocidade em gradientes de sacarose de traduzindo ribossomas de ribossomas não traduzindo.

Análise da Tradução Iniciação Durante condições de estresse por polysome Profiling

Precise control of mRNA translation is fundamental for eukaryotic cell homeostasis, particularly in response to physiological and pathological stress. ...

analysis-translation-initiation-during-stress-conditions-polysome

Research

JoVE Journal

Biology

18.2K visualizações.  Laval University.  Aqui, descrevemos um método para analisar mudanças na iniciação da tradução do mRNA de células eucarióticas em resposta a condições de estresse. Este método baseia-se na separação de velocidade em gradientes de sacarose de traduzindo ribossomas de ribossomas não traduzindo. 

Vídeo: Analysis of Translation Initiation During Stress Conditions by Polysome Profiling

Monitoring Plant Hormones During Stress Responses

Plant hormones and related signaling compounds play an important role in the regulation of plant responses to various environmental stimuli and stresses. Among the most severe stresses are insect herbivory, pathogen infection, and drought stress. For each of these stresses a specific set of hormones and/or combinations thereof are known to fine-tune the responses, thereby ensuring the plant's survival. The major hormones involved in the regulation of these responses are jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA). To better understand the role of individual hormones as well as their potential interaction during these responses it is necessary to monitor changes in their abundance in a temporal as well as in a spatial fashion. For the easy, sensitive, and reproducible quantification of these and other signaling compounds we developed a method based on vapor phase extraction and gas chromatography/mass spectrometry (GC/MS) analysis (1, 2, 3, 4). After extracting these compounds from the plant tissue by acidic aqueous 1-propanol mixed with dichloromethane the carboxylic acid-containing compounds are methylated, volatilized under heat, and collected on a polymeric absorbent. After elution into a sample vial the analytes are separated by gas chromatography and detected by chemical ionization mass spectrometry. The use of appropriate internal standards then allows for the simple quantification by relating the peak areas of analyte and internal standard.

A simple method is provided that allows for the rapid extraction and analysis of multiple plant hormones from small tissue samples. The procedure uses vapor phase extraction as the solemn purification step. Samples are analyzed by GC/MS with chemical ionization that produces mainly (M+1)+ ions.

Monitoramento hormônios vegetais Durante Respostas ao Estresse

Plant hormones and related signaling compounds play an important role in the regulation of plant responses to various environmental stimuli and stresses. ...

Biologia

Antibody Profiling by Luciferase Immunoprecipitation Systems (LIPS)

Technologies for comprehensively understanding and quantifying antibody profiles to autoantigens and infectious agents may yield new insights into disease mechanisms and may elucidate new markers to substratify disease with different clinical features and better understand pathogenesis. We have developed a highly quantitative method called Luciferase Immunoprecipitation Systems (LIPS) for profiling patient sera antibody responses to autoantigens and pathogen antigens associated with infection. Unlike ELISAs, the highly sensitive LIPS is easily implemented to survey humoral serological response profiles to different antigens in a universal format and produces dynamic antibody titer ranges up to 6 log10 for some antigens. In these studies, quantitative profiling by LIPS of patient humoral responses against panels of antigens or even the entire proteome of some pathogens (i.e. HIV), is typically more informative than testing a single antigen by ELISA. In addition, LIPS also eliminates time and effort needed to produce highly purified antigens as well as the labor-intensive assay optimization steps needed for standard ELISAs. Here we provide a detailed protocol describing the technical aspects of performing LIPS assays for readily profiling antibody responses to single or multiple antigens.

Antibody Profiling by Luciferase Immunoprecipitation Systems LIPS

The technical aspects of performing LIPS (Luciferase Immunoprecipitation Systems) are described. The overall approach involves expressing chimeric genes encoding antigens fused to Renilla luciferase (Ruc) in mammalian cells. Crude Ruc-antigen extracts are then prepared and, without purification, employed in immunoprecipitation assays to quantify antibodies.

Perfil de anticorpos por sistemas de imunoprecipitação luciferase (LIPS)

Technologies for comprehensively understanding and quantifying antibody profiles to autoantigens and infectious agents may yield new insights into disease ...

Analysis of Oxidative Stress in Zebrafish Embryos

High levels of reactive oxygen species (ROS) may cause a change of cellular redox state towards oxidative stress condition. This situation causes oxidation of molecules (lipid, DNA, protein) and leads to cell death. Oxidative stress also impacts the progression of several pathological conditions such as diabetes, retinopathies, neurodegeneration, and cancer. Thus, it is important to define tools to investigate oxidative stress conditions not only at the level of single cells but also in the context of whole organisms. Here, we consider the zebrafish embryo as a useful in vivo system to perform such studies and present a protocol to measure in vivo oxidative stress. Taking advantage of fluorescent ROS probes and zebrafish transgenic fluorescent lines, we develop two different methods to measure oxidative stress in vivo: i) a &#8220;whole embryo ROS-detection method&#8221; for qualitative measurement of oxidative stress and ii) a &#8220;single-cell&#160;ROS detection method&#8221; for quantitative measurements of oxidative stress. Herein, we demonstrate the efficacy of these procedures by increasing oxidative stress in tissues by oxidant agents and physiological or genetic methods. This protocol is amenable for forward genetic screens and it will help address cause-effect relationships of ROS in animal models of oxidative stress-related pathologies such as neurological disorders and cancer.

Here we report a protocol to measure oxidative stress in living zebrafish embryos. This procedure allows reactive oxygen species (ROS) detection in both whole embryo tissues and single-cell populations. This protocol will accomplish both qualitative and quantitative analyses.

Análise do estresse oxidativo em embriões Zebrafish

High levels of reactive oxygen species (ROS) may cause a change of cellular redox state towards oxidative stress condition. This situation causes ...

Profiling Individual Human Embryonic Stem Cells by Quantitative RT-PCR

Heterogeneity of stem cell population hampers detailed understanding of stem cell biology, such as their differentiation propensity toward different lineages. A single cell transcriptome assay can be a new approach for dissecting individual variation. We have developed the single cell qRT-PCR method, and confirmed that this method works well in several gene expression profiles. In single cell level, each human embryonic stem cell, sorted by OCT4::EGFP positive cells, has high expression in OCT4, but a different level of NANOG expression. Our single cell gene expression assay should be useful to interrogate population heterogeneities.

Single cell gene expression assay is needed for understanding stem cell heterogeneities.

Profiling Individual células estaminais embrionárias humanas por RT-PCR quantitativo

Heterogeneity of stem cell population hampers detailed understanding of stem cell biology, such as their differentiation propensity toward different ...

Polysome Fractionation and Analysis of Mammalian Translatomes on a Genome-wide Scale

mRNA translation plays a central role in the regulation of gene expression and represents the most energy consuming process in mammalian cells. Accordingly, dysregulation of mRNA translation is considered to play a major role in a variety of pathological states including cancer. Ribosomes also host chaperones, which facilitate folding of nascent polypeptides, thereby modulating function and stability of newly synthesized polypeptides. In addition, emerging data indicate that ribosomes serve as a platform for a repertoire of signaling molecules, which are implicated in a variety of post-translational modifications of newly synthesized polypeptides as they emerge from the ribosome, and/or components of translational machinery. Herein, a well-established method of ribosome fractionation using sucrose density gradient centrifugation is described. In conjunction with the in-house developed &#8220;anota&#8221; algorithm this method allows direct determination of differential translation of individual mRNAs on a genome-wide scale. Moreover, this versatile protocol can be used for a variety of biochemical studies aiming to dissect the function of ribosome-associated protein complexes, including those that play a central role in folding and degradation of newly synthesized polypeptides.

Ribosomes play a central role in protein synthesis. Polyribosome (polysome) fractionation by sucrose density gradient centrifugation allows direct determination of translation efficiencies of individual mRNAs on a genome-wide scale. In addition, this method can be used for biochemical analysis of ribosome- and polysome-associated factors such as chaperones and signaling molecules.

Polysome Fracionamento e Análise de mamíferos Translatomes em uma escala genômica

mRNA translation plays a central role in the regulation of gene expression and represents the most energy consuming process in mammalian cells. ...

Assessment of Selective mRNA Translation in Mammalian Cells by Polysome Profiling

Regulation of protein synthesis represents a key control point in cellular response to stress. In particular, discreet RNA regulatory elements were shown to allow to selective translation of specific mRNAs, which typically encode for proteins required for a particular stress response. Identification of these mRNAs, as well as the characterization of regulatory mechanisms responsible for selective translation has been at the forefront of molecular biology for some time. Polysome profiling is a cornerstone method in these studies. The goal of polysome profiling is to capture mRNA translation by immobilizing actively translating ribosomes on different transcripts and separate the resulting polyribosomes by ultracentrifugation on a sucrose gradient, thus allowing for a distinction between highly translated transcripts and poorly translated ones. These can then be further characterized by traditional biochemical and molecular biology methods. Importantly, combining polysome profiling with high throughput genomic approaches allows for a large scale analysis of translational regulation.

The ability of cells to adapt to stress is crucial for their survival. Regulation of mRNA translation is one such adaptation strategy, providing for rapid regulation of the proteome. Here, we provide a standardized polysome profiling protocol to identify specific mRNAs that are selectively translated under stress conditions.

Avaliação da Seletiva mRNA Tradução em células de mamíferos por polissoma Profiling

Regulation of protein synthesis represents a key control point in cellular response to stress. In particular, discreet RNA regulatory elements were shown ...

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, corticotrophin releasing hormone (CRH) is released from the hypothalamus in the brain. This stimulates the release of adrenocorticotrophic hormone (ACTH) from the pituitary gland, which in turn stimulates release of glucocorticoids from the adrenal gland. In horses the glucocorticoid corticosterone is responsible for several adaptations needed to support equine flight behaviour and subsequent removal from the aversive situation. Corticosterone metabolites can be detected in the feces of horses and assessment offers a non-invasive option to evaluate long term patterns of adrenal activity. Fecal assessment offers advantages over other techniques that monitor adrenal activity including blood plasma and saliva analysis. The non-invasive nature of the method avoids sampling stress which can confound results. It also allows the opportunity for repeated sampling over time and is ideal for studies in free ranging horses. This protocol describes the enzyme linked immunoassay (EIA) used to assess feces for corticosterone, in addition to the associated biochemical validation.

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. The method offers a non-invasive option to assess long term patterns in both domestic and free ranging horses. This protocol describes the enzyme linked immunoassay involved and the associated biochemical validation.

Fecal Análise de glicocorticóides: Non-invasive Monitoring Adrenal em eqüídeos

Adrenal activity can be assessed in the equine species by analysis of feces for corticosterone metabolites. During a potentially aversive situation, ...

An Easy Method for Plant Polysome Profiling

Translation of mRNA to protein is a fundamental and highly regulated biological process. Polysome profiling is considered as a gold standard for the analysis of translational regulation. The method described here is an easy and economical way for fractionating polysomes from various plant tissues. A sucrose gradient is made without the need for a gradient maker by sequentially freezing each layer. Cytosolic extracts are then prepared in a buffer containing cycloheximide and chloramphenicol to immobilize the cytosolic and chloroplastic ribosomes to mRNA and are loaded onto the sucrose gradient. After centrifugation, six fractions are directly collected from the bottom to the top of the gradient, without piercing the ultracentrifugation tube. During collection, the absorbance at 260 nm is read continuously to generate a polysome profile that gives a snapshot of global translational activity. Fractions are then pooled to prepare three different mRNA populations: the polysomes, mRNAs bound to several ribosomes; the monosomes, mRNAs bound to one ribosome; and mRNAs that are not bound to ribosomes. mRNAs are then extracted. This protocol has been validated for different plants and tissues including Arabidopsis thaliana seedlings and adult plants, Nicotiana benthamiana, Solanum lycopersicum, and Oryza sativa leaves.

This protocol describes an easy method to extract and fractionate transcripts from plant tissues on the basis of the number of bound ribosomes. It allows a global estimate of translation activity and the determination of the translational status of specific mRNAs.

Um método fácil para a planta polysome Profiling

Translation of mRNA to protein is a fundamental and highly regulated biological process. Polysome profiling is considered as a gold standard for the ...

Analysis of the Gap Junction-dependent Transfer of miRNA with 3D-FRAP Microscopy

Small antisense RNAs, like miRNA and siRNA, play an important role in cellular physiology and pathology and, moreover, can be used as therapeutic agents in the treatment of several diseases. The development of new, innovative strategies for miRNA/siRNA therapy is based on an extensive knowledge of the underlying mechanisms. Recent data suggest that small RNAs are exchanged between cells in a gap junction-dependent manner, thereby inducing gene regulatory effects in the recipient cell. Molecular biological techniques and flow cytometric analysis are commonly used to study the intercellular exchange of miRNA. However, these methods do not provide high temporal resolution, which is necessary when studying the gap junctional flux of molecules. Therefore, to investigate the impact of miRNA/siRNA as intercellular signaling molecules, novel tools are needed that will allow for the analysis of these small RNAs at the cellular level. The present protocol describes the application of three-dimensional fluorescence recovery after photobleaching (3D-FRAP) microscopy to elucidating the gap junction-dependent exchange of miRNA molecules between cardiac cells. Importantly, this straightforward and non-invasive live-cell imaging approach allows for the visualization and quantification of the gap junctional shuttling of fluorescently labeled small RNAs in real time, with high spatio-temporal resolution. The data obtained by 3D-FRAP confirm a novel pathway of intercellular gene regulation, where small RNAs act as signaling molecules within the intercellular network.

Here, we describe the application of three-dimensional fluorescence recovery after photobleaching (3D-FRAP) for the analysis of the gap junction-dependent shuttling of miRNA. In contrast to commonly applied methods, 3D-FRAP allows for the quantification of the intercellular transfer of small RNAs in real time, with high spatio-temporal resolution.

Análise do Gap Junction-dependente Transferência de miARN com 3D-FRAP Microscopia

Small antisense RNAs, like miRNA and siRNA, play an important role in cellular physiology and pathology and, moreover, can be used as therapeutic agents ...

In Vitro Analysis of E3 Ubiquitin Ligase Function

The covalent attachment of ubiquitin (Ub) to internal lysine residue(s) of a substrate protein, a process termed ubiquitylation, represents one of the most important post-translational modifications in eukaryotic organisms. Ubiquitylation is mediated by a sequential cascade of three enzyme classes including ubiquitin-activating enzymes (E1 enzymes), ubiquitin-conjugating enzymes (E2 enzymes), and ubiquitin ligases (E3 enzymes), and sometimes, ubiquitin-chain elongation factors (E4 enzymes). Here, in vitro protocols for ubiquitylation assays are provided, which allow the assessment of E3 ubiquitin ligase activity, the cooperation between E2-E3 pairs, and substrate selection. Cooperating E2-E3 pairs can be screened by monitoring the generation of free poly-ubiquitin chains and/or auto-ubiquitylation of the E3 ligase. Substrate ubiquitylation is defined by selective binding of the E3 ligase and can be detected by western blotting of the in vitro reaction. Furthermore, an E2~Ub discharge assay is described, which is a useful tool for the direct assessment of functional E2-E3 cooperation. Here, the E3-dependent transfer of ubiquitin is followed from the corresponding E2 enzyme onto free lysine amino acids (mimicking substrate ubiquitylation) or internal lysines of the E3 ligase itself (auto-ubiquitylation). In conclusion, three different in vitro protocols are provided that are fast and easy to perform to address E3 ligase catalytic functionality.

In Vitro Analysis of E3 Ubiquitin Ligase Function

The present study provides detailed in vitro ubiquitylation assay protocols for the analysis of E3 ubiquitin ligase catalytic activity. Recombinant proteins were expressed using prokaryotic systems such as Escherichia coli culture.

In vitro Análise da Função Ligase E3 Ubiquitin

The covalent attachment of ubiquitin (Ub) to internal lysine residue(s) of a substrate protein, a process termed ubiquitylation, represents one of the ...