Os autores gostariam de agradecer Glen Slocum (Medical College of Wisconsin) e Colleen A. Lavin (Nikon Instruments Inc) para assistência técnica excelente, com experimentos de microscopia. Este estudo foi financiado pelos Institutos Nacionais de Saúde concede R01 HL108880 (a AS), R01 DK095029 (para OPO) e K99 HL116603 (TSP), National Kidney Foundation IG1724 (TSP), American Heart Association 13GRNT16220002 (para OPO) e o Ben J. Lipps Research Fellowship da Sociedade Americana de Nefrologia (para DVI).

Os procedimentos experimentais descritos abaixo foram aprovados pelo Comitê de Uso e Cuidado Animal Institucional no Medical College of Wisconsin e University of Health Science Center Texas em Houston e estavam de acordo com o National Institutes of Health Guide para o Cuidado e Uso de Animais de Laboratório. A Figura 1 demonstra os passos principais do processo de isolamento e processamento do tecido. Resumidamente, os rins de ratos SD ou PCK são utilizados para o isolamento manual das monocamadas epiteliais de recolha de condutas, quer a partir de túbulos ou cistos não-marcado saudáveis. Aqui nós estudados rins de 4-16 semanas de idade ratos PCK 10,13. 1. Isolamento de renais Cistos e Palhinha Conexão (CNT) / ductos coletores (CD) Segmentos <ol><li> Anestesiar animal experimental com isoflurano (5% de indução, de 1,5 a 2,5% de manutenção) / Medical Grade O 2 ou outro método aprovado. Os animais devem ser continuamente monitorado para garantir le adequadavel da anestesia. Reação taxa e toe pitada respiratório estável são utilizados para confirmar a anestesia adequada. </li><li> Execute laparotomia e liberar os rins com tampão fosfato salino (PBS) através da aorta abdominal 17. <ol><li> Prepare um cateter tubo de polietileno (PE50) e conectá-lo a uma bomba de seringa preenchida com PBS. Corte a pele e parede abdominal ao longo da linha alba, em seguida, fazer uma incisão abdominal transversa através do abdômen de lado a lado e deslocar os órgãos abdominais com cotonetes para obter o acesso à aorta descendente com ramificações mesentéricas e celíacas artérias. Umedeça os órgãos internos com solução salina quente durante procedimentos adicionais para impedir a sua secura. </li><li> Coloque uma ligadura (# 1) em torno das artérias mesentéricas e celíacas e outra ligadura (# 2) em torno da aorta sob o diafragma (não amarrar). Delicadamente separar a. abdominalis por Blunt dissecar os tecidos conectivos em torno dela com uma pinça fina e colocar duas ligaduras ~ 3mm abaixo da artéria renal esquerda (# 3) e acima da bifurcação artérias ilíacas (# 4). </li><li> Amarre ligadura # 4 e anexar uma braçadeira navio ao redor da aorta, entre a artéria renal esquerda e ligadura # 3. Faça uma incisão entre o grampo e ligadura # 4 a cateterização da aorta, use ligadura # 3 para fixar firmemente o cateter. </li><li> Solte a braçadeira e certifique-se que o pulso de sangue é visível no cateter para garantir a instalação adequada. Comece a perfusão a um caudal de 6 ml / min, o laço ligaduras # 1 e # 2, e cortar a veia renal esquerda. Continue lavando por 1-2 min até que os órgãos estão completamente empalideceu. </li><li> Corte vasos sanguíneos renais, uretra e que cercam tecidos conjuntivos e adiposas com uma tesoura para recolher os rins. Em seguida, faça uma pequena lágrima em cápsula renal e descasque os rins a decapsulate-los. Colocar os rins em PBS gelado. Eutanásia é confirmada através de uma toracotomia. </li></ol></li><li> Prepare 5 x 5 mm chips de vidro de cobertura revestidas com poli-L-lisina. Corte uma tampa glass com um lápis e diamante lugar aproximadamente 20 ul de solução esterilizada por filtração de poli-L-lisina em cada chip de vidro de 0,01%. Prepare salina e duas pinças de relojoeiro para dissecção. </li><li> Cortar os rins com uma lâmina de barbear ao longo do plano frontal em fatias de ~ 1-2 mm de espessura. Coloque uma das fatias sob um microscópio estereoscópico. Isolamento de tecidos deve ser feito em solução salina gelada. </li><li> Localize cistos sob microscópio estereoscópico como cavidades em forma redonda (Figura 2A); suas paredes contêm frequentemente proeminente rede de vasos sanguíneos proliferaram. Utilizando uma pinça de ponta fina dissecar a camada epitelial interno de um quisto tão fino quanto possível para obter uma área de monocamada. Una-o a um chip de vidro cobertos com poli-L-lisina. Pegajosa superfície Poli-L-Lisina permite ao pesquisador posicionar firmemente a camada interna cisto no vidro. Exponha o cisto com o lado apical para fornecer acesso para as pipetas (Figura 2B). </li><li> Use PCK ou SD rato criançafatias centrais ney contendo papila para o isolamento de não dilatados CNT / CCDsegments 18-21. NOTA: tecidos papilares são mais duráveis ​​do córtex e segurando faixas tubulares papilar, com uma pinça e rasgando ao longo eixo radial a fatia pode ser clivada em setores finas. Túbulos individuais são visíveis e podem ser puxado para fora para ser colocado em chips de vidro capa. </li><li> Identificar os segmentos CNT / CCD por bifurcações, maior transparência do que túbulos proximais e células proeminentemente visíveis grandes (Figura 2C). Coloque o chip de vidro com tampa túbulos anexados sob um microscópio equipado com micromanipuladores adequadas para micropipetas condução. Usando micropipetas afiadas túbulos split-abertos e anexar suas bordas ao vidro para tornar a superfície apical acessível (Figura 2D). </li></ol> Eletrofisiologia 2. Single Canal patch-clamp <ol><li> Encha a câmara de patch-clamp com solução de banho e transfira o chip tampa de vidrocom tecidos isolados para a câmara. Certifique-se de que as micropipetas de patch-clamp têm resistência de 10/07 mohms para medições confiáveis ​​sobre células-anexado (celulares). </li><li> Para as medições ligado de células, definir a relação de ganho do amplificador de 20x e de baixo passar as correntes em 300 Hz por um filtro de oito pólos Bessel. Para a monitorização canais ENaC, usar uma solução de banho, em mM: NaCl 150, CaCl2 1, MgCl2 2, 10 HEPES (pH 7,4); pipeta: 140 LiCl, 2 de MgCl2 e 10 HEPES (pH 7,4). </li><li> Realizar um experimento patch-clamp convencional em um modo ligado à célula 10. Seleccionar uma célula na monocamada epitelial e aproximar a pipeta para a membrana apical. Formar uma vedação de alta resistência entre uma pipeta e membrana celular através da aplicação de sucção suave. Uma vez que um selo gigaohm resistente de alta é formado, um protocolo livre de gap em um potencial de realização deve ser iniciado para a atividade de monitoramento do canal de interesse. </li><li> Loja gap-livres únicos dados atuais do canal de gigaSelos Ohm para análise posterior. Analisar os eventos de canal utilizando um pacote de software geralmente fornecidos com configurações de patch-clamp 18. Calcular a actividade de canal como npo em que N se refere ao número de canais activos na amostra e P é o probabilidade média aberta dos canais. NOTA: Use cistos isolados ou túbulos em experimentos de patch-clamp para não mais de 30 min. </li></ol> 3. Raciometrico epifluorescência Medidas de intracelular concentração de cálcio nas células epiteliais <ol><li> Use 5 mM Fura-02:00 dissolvido em DMSO. Solução estoque alíquota em 500 mL tubos cônicos individuais (cerca de 10 mL). Proteger da luz e armazenar no congelador a -20 ° C por até seis meses. </li><li> Incubar cistos isolados e túbulos dividir-aberto para 30-40 min no PSS (em mM: NaCl 145, KCl 4,5, 2 MgCl2, CaCl2 2 e 10 HEPES a pH 7,35) contendo 5 mM Fura-02:00 corante e 0.05% de ácido plurónico para ajudar a dispersar os ésteres de acetoximetilo. Para que, no lugar dos tecidos 3,5 cm de placa de carregamento cocktail contendo, proteger da luz e incubar num agitador lento à temperatura ambiente. </li><li> Mudar Fura-2 AM contendo meios para limpar PSS após incubação e colocar o tecido sob um microscópio para executar mais imagiologia de epifluorescência. </li><li> Ligue câmara CCD e fonte de luz estável (sistema de monocromador) equipado com roda de filtro (cada posição do filtro pode ser associado com o seu próprio nível de atenuação, seleccionado cada vez que o filtro é chamado). </li><li> Encontre o tecido no campo brilhante. Mudar para detecção do sinal de fluorescência e ajustar a intensidade da fonte de luz usando filtros de densidade neutra e potência da lâmpada para evitar a saturação do sinal. </li><li> Monitorar Fura-2 AM de fluorescência na amostra de tecido com excitação a 340/380 nm raciométrica com uma frequência de 0,125 Hz ou superior. Use um / NA 1.3 ou similar lente objetiva de 40 × para resolu adequadação imagem. </li><li> Para o processamento e cálculos imagem importar a seqüência de imagens. Certifique-se de dividir os canais e usar um modo hyperstack em tons de cinza. Seleccione várias regiões de interesse (células únicas quisto ou áreas seleccionadas de tecido cístico) e o cálculo dos valores de intensidade para cada um dos canais (340 e 380 nm) para o software de análise de dados preferido; valores de intensidade fundo subtrair de cada ponto de dados. </li><li> Para cada ponto de tempo de calcular a relação entre as intensidades de Fura-2 AM 340 a 380 canais. Gráfico de dispersão / linha mudanças em tempo ponto de Ca 2+ transitória para cada região e calcular valores médios / SE. </li></ol>

The authors have nothing to disclose.

Descrevemos aqui aplicações da técnica de patch-clamp convencional e imagiologia de epifluorescência cálcio para monocamadas epiteliais císticas derivados de um modelo murino de ARPKD genética. O protocolo consiste em três etapas, das quais a maior atenção deve ser dada ao isolamento dos cistos (passo 1.5 da seção de protocolos) e aos estudos eletrofisiológicos. Estes procedimentos fundamentais requerem treinamento extenso e paciência, eo leitor não deve ser frustrado ao mesmo tempo. <p class="jove_co...

Canais de iões desempenhar um papel importante em muitas funções fisiológicas, incluindo crescimento e diferenciação celular. Doenças policística dominante autossómica recessiva e nos rins (ADPKD e ARPKD, respectivamente) são doenças genéticas caracterizadas pelo desenvolvimento de quistos renais cheios de fluido da origem nas células epiteliais tubulares. ADPKD é causada por mutações de genes PKD1 ou PKD2 codificam polycystins 1 e 2, proteínas de membrana envolvidas na regulação da proliferação e diferenciação celular. PKD2, por si só ou como um complexo com PKD1, também funcionar como um catião de Ca2 + -permeable canal 1. As mutações do gene que codifica PKHD1 fibrocystin (uma proteína do tipo receptor-associado cílios envolvidos na tubulogenesis e / ou manutenção da polaridade do epitélio) são o impulso genética da ARPKD 2. Crescimento do cisto é um fenômeno complexo, acompanhado de proliferação perturbado 3,4, angiogênese 5, desdiferenciação e perda de polardade de células tubulares 6-8. Reabsorção defeituoso e secreção aumentada no epitélio cístico contribuir para o acúmulo de líquido no lúmen e cisto expansão 9,10. Fluxo-dependente prejudicada [Ca2 +] i sinalização também tem sido associada a cistogénese durante PKD 11-15. Aqui, nós descrevemos um método adequado para medições de patch-clamp da actividade do canal único e níveis intracelulares de Ca 2+ em monocamadas epiteliais císticas isolados de ratos PCK. Este método foi aplicado com sucesso por nós para caracterizar de actividade do canal de Na + epitelial (ENaC) e 10 [Ca 2+] i induzidas por processos dependentes de Ca 2+ e TRPV4 -permeable purinérgico cascata de sinalização 13. Nestes estudos utilizou-se ratos PCK, um modelo de ARPKD causada por uma mutação espontânea no gene PKHD1. A cepa PCK foi originally derivada a partir de ratos 16 ratos SD, assim, são utilizados como um controlo apropriado para comparação com a estirpe PCK Sprague-Dawley (SD). Como resultado, ambos os segmentos dos néfrons de ratos SD e dutos não dilatado coleta isolados de ratos mesmas PCK pode servir como dois grupos de comparação diferentes para fazer experimentos sobre epitélio cística.

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			<td height="21" style="height:21px;width:283px;">Fura-2 AM</td>
			<td style="width:219px;">Life Technologies</td>
			<td style="width:183px;">F-14185</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Flou-8</td>
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			<td style="width:183px;">21091</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Poly-L-lysine</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">P4707</td>
			<td style="width:333px;"></td>
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			<td height="21" style="height:21px;width:283px;">Pluronic acid</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">F-68&#160;</td>
			<td style="width:333px;">solution</td>
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			<td height="21" style="height:21px;width:283px;">Shaker</td>
			<td style="width:219px;">Boekel Scientific</td>
			<td style="width:183px;">260350</td>
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			<td height="21" style="height:21px;width:283px;">Light source</td>
			<td style="width:219px;">Sutter Instrument Co</td>
			<td style="width:183px;">Lambda XL</td>
			<td style="width:333px;">with integrated shutter/filter wheel driver</td>
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			<td height="21" style="height:21px;width:283px;">Neutral density filters</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;"></td>
			<td style="width:333px;">ND4, ND8</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Objective</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">SFluo&#160;</td>
			<td style="width:333px;">40/1.3 DIC WD 0.22&#160;&#160; oil</td>
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			<td height="21" style="height:21px;width:283px;">Camera</td>
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			<td style="width:183px;">Zyla sCMOS</td>
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			<td height="23" style="height:23px;width:283px;">Nikon&#160; microscope (inverted)</td>
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			<td height="21" style="height:21px;width:283px;">Cover Glass</td>
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			<td style="width:183px;">6661B52</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Diamond pencil</td>
			<td style="width:219px;">Fisher Scientific</td>
			<td style="width:183px;">22268912</td>
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			<td height="21" style="height:21px;width:283px;">Image acquisition software</td>
			<td style="width:219px;">Nikon</td>
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			<td height="41" style="height:41px;width:283px;">Image analysis software</td>
			<td style="width:219px;">ImageJ</td>
			<td style="width:183px;">http://imagej.nih.gov/</td>
			<td style="width:333px;">ND Utility plugin allows to import images in the native Nikon Instruments .nd2 format</td>
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			<td height="21" style="height:21px;width:283px;">Recording/perfusion chamber</td>
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			<td style="width:183px;">RC-26</td>
			<td style="width:333px;"></td>
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			<td style="width:183px;">Digidata 1440A</td>
			<td style="width:333px;">Axon Digidata&#174; System</td>
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			<td height="21" style="height:21px;width:283px;">Low Pass Filter</td>
			<td style="width:219px;">Warner Instruments</td>
			<td style="width:183px;">LPF-8</td>
			<td style="width:333px;">8 pole Bessel</td>
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			<td height="21" style="height:21px;width:283px;">Borosilicate glass capillaries</td>
			<td style="width:219px;">World Precision Instruments</td>
			<td style="width:183px;">1B150F-4</td>
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			<td height="29" style="height:29px;width:283px;">Micropipette Puller</td>
			<td style="width:219px;">Sutter Instrument Co</td>
			<td style="width:183px;">P-97</td>
			<td style="width:333px;">Flaming/Brown type micropipette puller</td>
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			<td height="21" style="height:21px;width:283px;">Microforge</td>
			<td style="width:219px;">Narishige</td>
			<td style="width:183px;">MF-830</td>
			<td style="width:333px;">Japan</td>
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			<td height="21" style="height:21px;width:283px;">Motorized Micromanipulator</td>
			<td style="width:219px;">Sutter Instrument Co</td>
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			<td height="21" style="height:21px;width:283px;">Inverted microscope</td>
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			<td style="width:219px;">TMC</td>
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			<td style="width:333px;">equipped with Faraday cage</td>
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			<td height="21" style="height:21px;width:283px;">Recording/perfusion chamber</td>
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			<td height="21" style="height:21px;width:283px;">Temperature controlled surgical table&#160;</td>
			<td style="width:219px;">MCW core</td>
			<td style="width:183px;"></td>
			<td style="width:333px;">for rodents</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Binocular stereomicroscope</td>
			<td style="width:219px;">Nikon</td>
			<td style="width:183px;">SMZ745</td>
			<td style="width:333px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Syringe pump-based perfusion system</td>
			<td style="width:219px;">Harvard Apparatus</td>
			<td style="width:183px;"></td>
			<td style="width:333px;"></td>
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			<td height="21" style="height:21px;width:283px;">polyethylene tubing</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;">PE50</td>
			<td style="width:333px;"></td>
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			<td height="21" style="height:21px;width:283px;">Isofluorane anesthesia</td>
			<td style="width:219px;"><a href="http://www.vetequip.com/">http://www.vetequip.com/</a></td>
			<td style="width:183px;">911103</td>
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			<td height="21" style="height:21px;width:283px;"></td>
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			<td height="21" style="height:21px;width:283px;">Other basic reagents</td>
			<td style="width:219px;">Sigma-Aldrich</td>
			<td style="width:183px;"></td>
			<td></td>
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implementing patch clamp and live fluorescence microscopy to monitor functional properties of freshly isolated pkd epithelium

Iniciação cisto e expansão durante a doença renal policística é um processo complexo, caracterizado por anormalidades na proliferação celular tubular, acúmulo de líquido luminal e formação de matriz extracelular. Atividade de canais iônicos e sinalização intracelular de cálcio são parâmetros fisiológicos fundamentais que determinam funções do epitélio tubular. Foi desenvolvido um método adequado para observação em tempo real da actividade de canais de iões com a técnica de patch-clamp e registo de Ca2 + intracelular em monocamadas epiteliais nível isolados de fresco a partir de quistos renais. PCK ratos, um modelo genético de doença renal policística autossômica recessiva (DRPAR), foram usados ​​aqui para ex vivo análise de canais iônicos e fluxo de cálcio. Aqui descrito é um procedimento detalhado passo-a-passo projetado para isolar monocamadas cística e túbulos não dilatado de PCK ou ratos normais Sprague Dawley (SD), e monitorar a atividade de canal único e de Ca 2+ intracelular dinâmica.Este método não exige processamento enzimático e permite a análise de uma configuração nativa isolada de fresco de monocamada epitelial. Além disso, esta técnica é muito sensível a alterações de cálcio intracelular e gera imagens de alta resolução para medições precisas. Finalmente, isolado epitélio cística pode ser ainda utilizado para a coloração com anticorpos ou corantes, preparação de culturas primárias e purificação por vários ensaios bioquímicos.

Potencial envolvimento ENaC em cistogénese tem sido demonstrada em vários estudos que observadas factor de crescimento epidérmico interrompido (FEG) de sinalização na progressão de PKD 22-25 e a reabsorção de sódio anormal na ARPKD modelos murinos e de culturas de tecidos 26-28. Por exemplo, Veizis et al. Mostraram que a absorção sensíveis ao amiloride Na + é diminuída em células CD a partir do modelo não-ortólogas rato BPK de ARPKD 29. Nós demonstra...

Watch this Scientific Journal Video about Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium at JoVE.com

Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium

Canais de iões expressas em epitélio tubular renal, desempenha um papel significativo na patologia da doença poliquística do rim. Aqui nós descrevemos protocolos experimentais utilizados para a realização de análises e medições de nível de cálcio intracelular de patch-clamp no epitélio cístico recentemente isoladas de rins de roedores.

Implementando Grampo patch e ao vivo microscopia de fluorescência para monitorar propriedades funcionais de recentemente isolados PKD Epithelium

Cyst initiation and expansion during polycystic kidney disease is a complex process characterized by abnormalities in tubular cell proliferation, luminal ...

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Research

JoVE Journal

Biology

9.7K visualizações.  Medical College of Wisconsin.  Canais de iões expressas em epitélio tubular renal, desempenha um papel significativo na patologia da doença poliquística do rim. Aqui nós descrevemos protocolos experimentais utilizados para a realização de análises e medições de nível de cálcio intracelular de patch-clamp no epitélio cístico recentemente isoladas de rins de roedores. 

Vídeo: Implementing Patch Clamp and Live Fluorescence Microscopy to Monitor Functional Properties of Freshly Isolated PKD Epithelium

Methods for Patch Clamp Capacitance Recordings from the Calyx

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. Electrical recordings from the presynaptic terminal allow the measurement of action potentials, calcium channel currents, vesicle fusion (exocytosis) and subsequent membrane uptake (endocytosis). The fusion of vesicles containing neurotransmitter causes the vesicle membrane to be added to the cell membrane of the calyx. This increase in the amount of cell membrane is measured as an increase in capacitance. The subsequent reduction in capacitance indicates endocytosis, the process of membrane uptake or removal from the calyx membrane. Endocytosis, is necessary to maintain the structure of the calyx and it is also necessary to form vesicles that will be filled with neurotransmitter for future exocytosis events. Capacitance recordings at the calyx of Held have made it possible to directly and rapidly measure vesicular release and subsequent endocytosis in a mammalian CNS nerve terminal. In addition, the corresponding postsynaptic activity can be simultaneously measured by using paired recordings. Thus a complete picture of the presynaptic and postsynaptic electrical activity at a central nervous system synapse is achievable using this preparation. Here, the methods for slice preparation, morphological features for identification of calyces of Held, basic patch clamping techniques, and examples of capacitance recordings to measure exocytosis and endocytosis are presented.

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal.

Métodos para Recordings patch-clamp Capacitância da Calyx

We demonstrate the basic techniques for presynaptic patch clamp recording at the calyx of Held, a mammalian central nervous system nerve terminal. ...

Biologia

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

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

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

Gravação de patch-clamp de canais iônicos Expresso em Oócitos Xenopus

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

Pressure-polishing Pipettes for Improved Patch-clamp Recording

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording. We first developed this method for fabricating pipettes suitable for recording from small (&lt;3 m) neuronal cell bodies. The basic principal is similar to glass-blowing and combines air pressure and heat to modify the shape of patch pipettes prepared by a conventional micropipette puller. It can be applied to so-called soft (soda lime) and hard (borosilicate) glasses. Generally speaking, pressure polishing can reduce pipette resistance by 25% without decreasing the diameter of the tip opening (Goodman and Lockery, 2000). It can be applied to virtually any type of glass and requires only the addition of a high-pressure valve and fitting to a microforge. This technique is essential for recording from ultrasmall cells (&lt;5 m) and can also improve single-channel recording by minimizing pipette resistance. The blunt shape is also useful for perforated-patch clamp recording since this tip shape results in a larger membrane bleb available for perforation.

This is a guide to modifying the shape of glass micropipettes. Specifically, by using heat and air pressure the taper is widened without increasing the tip opening, leading to lower pipette resistance. This is critical to obtain low noise recordings of small cells but is useful in many applications.

Pressão polimento Pipetas para Gravação de patch-clamp melhorada

Pressure-polishing is a method for shaping glass pipettes for patch-clamp recording.  We first developed this method for fabricating pipettes suitable for ...

Time-lapse Imaging of Mitosis After siRNA Transfection

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and cellular content. Hallmark events of mitosis, such as chromosome movement, can be readily tracked on an individual cell basis using time-lapse fluorescence microscopy of mammalian cell lines expressing specific GFP-tagged proteins. In combination with RNAi-based depletion, this can be a powerful method for pinpointing the stage(s) of mitosis where defects occur after levels of a particular protein have been lowered. In this protocol, we present a basic method for assessing the effect of depleting a potential mitotic regulatory protein on the timing of mitosis. Cells are transfected with siRNA, placed in a stage-top incubation chamber, and imaged using an automated fluorescence microscope. We describe how to use software to set up a time-lapse experiment, how to process the image sequences to make either still-image montages or movies, and how to quantify and analyze the timing of mitotic stages using a cell-line expressing mCherry-tagged histone H2B. Finally, we discuss important considerations for designing a time-lapse experiment. This strategy is complementary to other approaches and offers the advantages of 1) sensitivity to changes in kinetics that might not be observed when looking at cells as a population and 2) analysis of mitosis without the need to synchronize the cell cycle using drug treatments. The visual information from such imaging experiments not only allows the sub-stages of mitosis to be assessed, but can also provide unexpected insight that would not be apparent from cell cycle analysis by FACS.

Here we describe a basic protocol to image and quantify the mitotic timing of live mammalian tissue culture cells after siRNA transfection.

Lapso de tempo de imagens de Mitose Depois de Transfection siRNA

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and ...

Fluorescence-based Measurement of Store-operated Calcium Entry in Live Cells: from Cultured Cancer Cell to Skeletal Muscle Fiber

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to replenish depleted endoplasmic reticulum (ER) or sarcoplasmic reticulum (SR) Ca2+ stores1,2. Since Ca2+ is a ubiquitous second messenger, it is not surprising to see that SOCE plays important roles in a variety of cellular processes, including proliferation, apoptosis, gene transcription and motility. Due to its wide occurrence in nearly all cell types, including epithelial cells and skeletal muscles, this pathway has received great interest3,4. However, the heterogeneity of SOCE characteristics in different cell types and the physiological function are still not clear5-7.
The functional channel properties of SOCE can be revealed by patch-clamp studies, whereas a large body of knowledge about this pathway has been gained by fluorescence-based intracellular Ca2+ measurements because of its convenience and feasibility for high-throughput screening. The objective of this report is to summarize a few fluorescence-based methods to measure the activation of SOCE in monolayer cells, suspended cells and muscle fibers5,8-10. The most commonly used of these fluorescence methods is to directly monitor the dynamics of intracellular Ca2+ using the ratio of F340nm and F380nm (510 nm for emission wavelength) of the ratiometric Ca2+ indicator Fura-2. To isolate the activity of unidirectional SOCE from intracellular Ca2+ release and Ca2+ extrusion, a Mn2+ quenching assay is frequently used. Mn2+ is known to be able to permeate into cells via SOCE while it is impervious to the surface membrane extrusion processes or to ER uptake by Ca2+ pumps due to its very high affinity with Fura-2. As a result, the quenching of Fura-2 fluorescence induced by the entry of extracellular Mn2+ into the cells represents a measurement of activity of SOCE9. Ratiometric measurement and the Mn+2 quenching assays can be performed on a cuvette-based spectrofluorometer in a cell population mode or in a microscope-based system to visualize single cells. The advantage of single cell measurements is that individual cells subjected to gene manipulations can be selected using GFP or RFP reporters, allowing studies in genetically modified or mutated cells. The spatiotemporal characteristics of SOCE in structurally specialized skeletal muscle can be achieved in skinned muscle fibers by simultaneously monitoring the fluorescence of two low affinity Ca2+ indicators targeted to specific compartments of the muscle fiber, such as Fluo-5N in the SR and Rhod-5N in the transverse tubules9,11,12.

The extent of store-operated Ca2+ entry (SOCE) can be monitored using fluorescent Ca2+ indicators. Mn2+ quenching of such indicators assays SOCE in cultured cells and skeletal muscle fibers. A technique allowing spatial and temporal resolution of SOCE by confocal imaging of mechanically skinned muscle fibers is also described.

Fluorescência baseada em Medição da loja operada entrada de cálcio em células vivas: a partir de células cancerosas cultivadas em fibra muscular esquelética

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to ...

Quantitative Live Cell Fluorescence-microscopy Analysis of Fission Yeast

Several microscopy techniques are available today that can detect a specific protein within the cell. During the last decade live cell imaging using fluorochromes like Green Fluorescent Protein (GFP) directly attached to the protein of interest has become increasingly popular 1. Using GFP and similar fluorochromes the subcellular localisations and movements of proteins can be detected in a fluorescent microscope. Moreover, also the subnuclear localisation of a certain region of a chromosome can be studied using this technique. GFP is fused to the Lac Repressor protein (LacR) and ectopically expressed in the cell where tandem repeats of the lacO sequence has been inserted into the region of interest on the chromosome2. The LacR-GFP will bind to the lacO repeats and that area of the genome will be visible as a green dot in the fluorescence microscope. Yeast is especially suited for this type of manipulation since homologous recombination is very efficient and thereby enables targeted integration of the lacO repeats and engineered fusion proteins with GFP 3. Here we describe a quantitative method for live cell analysis of fission yeast. Additional protocols for live cell analysis of fission yeast can be found, for example on how to make a movie of the meiotic chromosomal behaviour 4. In this particular experiment we focus on subnuclear organisation and how it is affected during gene induction. We have labelled a gene cluster, named Chr1, by the introduction of lacO binding sites in the vicinity of the genes. The gene cluster is enriched for genes that are induced early during nitrogen starvation of fission yeast 5. In the strain the nuclear membrane (NM) is labelled by the attachment of mCherry to the NM protein Cut11 giving rise to a red fluorescent signal. The Spindle Pole body (SPB) compound Sid4 is fused to Red Fluorescent Protein (Sid4-mRFP) 6. In vegetatively growing yeast cells the centromeres are always attached to the SPB that is embedded in the NM 7. The SPB is identified as a large round structure in the NM. By imaging before and 20 minutes after depletion of the nitrogen source we can determine the distance between the gene cluster (GFP) and the NM/SPB. The mean or median distances before and after nitrogen depletion are compared and we can thus quantify whether or not there is a shift in subcellular localisation of the gene cluster after nitrogen depletion.

The fission yeast, Schizosaccharomyces pombe, is a good model system to study basic cellular processes. Here we describe a method to perform quantitative live cell analysis of fission yeast. In this particular experiment we focus on organisation of the genome within the cell nucleus, but the method can also be used to study cytosolic factors.

Quantitativas de células vivas de Análise de microscopia de fluorescência de levedura

Several microscopy techniques are available today that can detect a specific protein within the cell. During the last decade live cell imaging using ...

Giant Liposome Preparation for Imaging and Patch-Clamp Electrophysiology

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify and explore the function of these important proteins. However, classical preparations, such as planar bilayers, limit the manipulations and experiments that can be performed on the reconstituted channel and its membrane environment. The more cell-like structure of giant liposomes permits traditional patch-clamp experiments without sacrificing control of the lipid environment.
Electroformation is an efficient mean to produce giant liposomes &gt;10 &mu;m in diameter which relies on the application of alternating voltage to a thin, ordered lipid film deposited on an electrode surface. However, since the classical protocol calls for the lipids to be deposited from organic solvents, it is not compatible with less robust membrane proteins like ion channels and must be modified. Recently, protocols have been developed to electroform giant liposomes from partially dehydrated small liposomes, which we have adapted to protein-containing liposomes in our laboratory.
We present here the background, equipment, techniques, and pitfalls of electroformation of giant liposomes from small liposome dispersions. We begin with the classic protocol, which should be mastered first before attempting the more challenging protocols that follow. We demonstrate the process of controlled partial dehydration of small liposomes using vapor equilibrium with saturated salt solutions. Finally, we demonstrate the process of electroformation itself. We will describe simple, inexpensive equipment that can be made in-house to produce high-quality liposomes, and describe visual inspection of the preparation at each stage to ensure the best results.

Reconstituting functional membrane proteins into giant liposomes of defined composition is a powerful approach when combined with patch-clamp electrophysiology. However, conventional giant liposome production may be incompatible with protein stability. We describe protocols for producing giant liposomes from pure lipids or small liposomes containing ion channels.

Preparação de lipossomas gigantes por Imagem e patch-clamp Eletrofisiologia

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify ...

One-channel Cell-attached Patch-clamp Recording

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate depends on properties intrinsic to each channel protein as well as the mechanism by which it is generated and controlled and represents an important area of current research. Information about the operational dynamics of ion channel proteins can be obtained by observing long stretches of current produced by a single molecule. Described here is a protocol for obtaining one-channel cell-attached patch-clamp current recordings for a ligand gated ion channel, the NMDA receptor, expressed heterologously in HEK293 cells or natively in cortical neurons. Also provided are instructions on how to adapt the method to other ion channels of interest by presenting the example of the mechano-sensitive channel PIEZO1. This method can provide data regarding the channel&#8217;s conductance properties and the temporal sequence of open-closed conformations that make up the channel&#8217;s activation mechanism, thus helping to understand their functions in health and disease.

Described here is a procedure for obtaining long stretches of current recording from one ion channel with the cell-attached patch-clamp technique. This method allows for observing, in real time, the pattern of open-close channel conformations that underlie the biological signal. These data inform about channel properties in undisturbed biological membranes.

Um canal de gravação de patch-clamp anexado-Cell

Ion channel proteins are universal devices for fast communication across biological membranes. The temporal signature of the ionic flux they generate ...

Reconstitution of a Transmembrane Protein, the Voltage-gated Ion Channel, KvAP, into Giant Unilamellar Vesicles for Microscopy and Patch Clamp Studies

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. However, commonly used protocols to grow GUVs must be modified in order to form GUVs containing functional transmembrane proteins. This article describes two dehydration-rehydration methods &#8212; electroformation and gel-assisted swelling &#8212; to form GUVs containing the voltage-gated potassium channel, KvAP. In both methods, a solution of protein-containing small unilamellar vesicles is partially dehydrated to form a stack of membranes, which is then allowed to swell in a rehydration buffer. For the electroformation method, the film is deposited on platinum electrodes so that an AC field can be applied during film rehydration. In contrast, the gel-assisted swelling method uses an agarose gel substrate to enhance film rehydration. Both methods can produce GUVs in low (e.g., 5 mM) and physiological (e.g., 100 mM) salt concentrations. The resulting GUVs are characterized via fluorescence microscopy, and the function of reconstituted channels measured using the inside-out patch-clamp configuration. While swelling in the presence of an alternating electric field (electroformation) gives a high yield of defect-free GUVs, the gel-assisted swelling method produces a more homogeneous protein distribution and requires no special equipment.

The reconstitution of the transmembrane protein, KvAP, into giant unilamellar vesicles (GUVs) is demonstrated for two dehydration-rehydration methods &#8212; electroformation, and gel-assisted swelling. In both methods, small unilamellar vesicles containing the protein are fused together to form GUVs that can then be studied by fluorescence microscopy and patch-clamp electrophysiology.

Reconstituição de uma proteína transmembrana, a voltagem-Ion Channel, KvAP, em Gigante Unilamelares Vesicles para microscopia e de Patch Estudos Grampo

Giant Unilamellar Vesicles (GUVs) are a popular biomimetic system for studying membrane associated phenomena. However, commonly used protocols to grow ...

Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli

Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells in the pathogenesis of various renal diseases has been established since podocyte injury leads to proteinuria and foot process effacement. It was previously reported that various endogenous agents may cause a dramatic overload in intracellular Ca2+ concentration in podocytes, presumably leading to albuminuria, and this likely occurs via calcium-conducting ion channels. Therefore, it appeared important to study calcium handling in the podocytes both under normal conditions and in various pathological states. However, available experimental approaches have remained somewhat limited to cultured and transfected cells. Although they represent a good basic model for such studies, they are essentially extracted from the native environment of the glomerulus. Here we describe the methodology of studying podocytes as a part of the freshly isolated whole glomerulus. This preparation retains the functional potential of the podocytes, which are still attached to the capillaries; therefore, podocytes remain in the environment that conserves the major parts of the glomeruli filtration apparatus. The present manuscript elaborates on two experimental approaches that allow 1) real-time detection of calcium concentration changes with the help of ratiometric confocal fluorescence microscopy, and 2) the recording of the single ion channels activity in the podocytes of the freshly isolated glomeruli. These methodologies utilize the advantages of the native environment of the glomerulus that enable researchers to resolve acute changes in the intracellular calcium handling in response to applications of various agents, measure basal concentration of calcium within the cells (for instance, to evaluate disease progression), and assess and manipulate calcium conductance at the level of single ion channels.

Changes in the intracellular calcium levels in the podocytes are one of the most important means to control the filtration function of glomeruli. Here we explain a high-throughput approach that allows detection of real-time calcium handling and single ion channels activity in the podocytes of the freshly isolated glomeruli.

Single-channel Análise e cálcio Criação de imagem do Podócitos do recentemente isolados glomérulos

Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells ...