We thank Lowell Cochran for expert videography assistance. The financial assistance of the Canadian Institutes of Health Research (CIHR), the Canadian Breast Cancer Foundation (CBCF, Ontario Chapter), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Breast Cancer Research Alliance, the Ontario Centers of Excellence, the Breast Cancer Action Kingston and the Clare Nelson bequest fund through grants to LR is gratefully acknowledged. SG was the recipient of an NSERC studentship. MG was supported by a postdoctoral fellowship from the US Army Breast Cancer Program, the Ministry of Research and Innovation of the Province of Ontario and the Advisory Research Committee of Queen&#8217;s University.

1. plaqueamento das células do Eletroporação Chambers <ol><li> Numa capela de fluxo laminar, as células trypsinize usando uma técnica estéril, como de costume. NOTA: É muito importante para eliminar por centrifugação todos os vestígios de tripsina, porque eles podem prejudicar propagação das células no vidro, daí a formação de adherens e junções comunicantes. </li><li> Pipetar 1 mL da suspensão de células nas câmaras de electroporação estéril fornecido com o electroporador em situ (Figura 1), e em lugar de um de 37 o C, incubadora de CO 2. NOTA: A adesão celular pode ser melhorada através de plaqueamento em fibronectina, colagénio, poli-lisina ou de células e tecido adesivo (ver Tabela Materiais). </li><li> Quando as células formaram uma camada confluente eles estão prontos para análise CIJH. </li></ol> 2. Eletroporação Procedimento Eletroporação para exame GJIC pode ser realizada fora de uma capela de fluxo laminar,uma vez que leva apenas alguns minutos. Se forem necessários tempos de incubação mais longos para uma experiência específica, em seguida, pode ser realizado inteiramente num exaustor de fluxo laminar. Em todos os casos, as câmaras onde são cultivadas as células têm de ser estéreis. <ol><li> Prepara-se uma / ml solução amarelo Lucifer 5 mg: Dissolver 10 mg de pó de LY (fornecida com o electroporador) em 2 ml de meio de crescimento isento de cálcio. Para os experimentos que requerem tempos de incubação mais longos, filtro de esterilizar a solução e armazenar a 4 ° C. </li><li> Aspirar o meio de crescimento e lavar as células com meio livre de cálcio, tendo o cuidado para não arranhar a monocamada ou secar as células. Se as células são secas têm geralmente núcleos mais escuras e pegar LY sem electroporação. O efeito é mais pronunciado no meio do slide que está mais exposto a correntes de ar (Figura 4F). </li><li> Com uma pipeta de Eppendorf, pipetar a solução corante para as células (400 ul para o conjunto da câmara), na extremidade da câmara, being cuidado para não tocar a camada de células. </li><li> Coloque a câmara no suporte fornecido com o electroporador e aplicar um impulso de força adequada (ver discussão). </li><li> Aspirar cuidadosamente um pouco da solução LY. Ele pode ser reutilizada uma segunda vez para experiências menos importantes. </li><li> Adicionar DMEM livre de cálcio com 10% de soro dialisado. </li><li> Incubar as células durante 3-5 minutos na incubadora para permitir a transferência de corante através de junções de hiato. NOTA: A inclusão de soro dialisado, neste ponto ajuda encerramento dos poros. </li><li> Lavar o corante não incorporado com DMEM isento de cálcio para a observação de células vivas. Alternativamente, as células podem ser fixadas nesta fase, por meio da adição de 4% de formaldeído para o bem, em seguida, lavadas com PBS (solução salina tamponada com fosfato). Em todos os casos, a lavagem deve remover todo o fundo. NOTA: Em experimentos preliminares para determinar as condições ideais, se a tensão é muito baixa, então é possível para permitir que as células se recuperar no incubator durante alguns minutos e electroporate mesma lâmina uma segunda vez, para economizar no custo de lâminas. </li></ol> 3. exame microscópico <ol><li> Observar as células sob iluminação de fluorescência, utilizando um microscópio invertido equipado com o filtro apropriado para o corante a ser utilizado. Para Lúcifer amarelo, excitação é 423nm, emissão de 555nm, filtro VCI para um microscópio Nikon IX70. </li><li> Eliminar efeitos de menisco, colocando uma lamela de vidro na parte superior do poço de plástico, depois do enchimento ele para o topo com o líquido, para examinar a morfologia das células sob contraste de fase. Para melhores imagens, o poço pode ser isolada a partir da lâmina, e a lamela colocada sobre a moldura. Para as células fixas, o poço pode ser preenchido com glicerol para observação microscópica, enquanto para as células vivas, deve ser preenchido com o meio de crescimento. NOTA: Lavagem e fotografando é mais fácil se as células são fixadas com formaldeído após a transferência do corante (passo 2.7 acima). Se as células não sãot fixo, a fluorescência é eliminada das células dentro de aproximadamente 60 min, dependendo do tipo de célula, da tensão e da quantidade de LY introduzido enquanto em células fixas fluorescência é mantida durante várias horas. No entanto, a fluorescência ou dissipa após se desvanece O / N a incubação, até mesmo em células fixadas. Por esta razão, deve ser feita fotografias logo após a electroporação (Figura 2). </li></ol> 4. quantificação de comunicação intercelular <ol><li> Fotografar as células com uma objectiva de 20x sob contraste de fase e fluorescência (Figura 3). </li><li> Identificar e marcar com uma estrela as células eletroporados na fronteira com a área não-electroporados (Figura 2, seta, borda eletroporação). </li><li> Identificar e marcar com um ponto de células fluorescentes no lado não-electroporado, em que o corante foi transferida através de junções de hiato (Figuras 3A e 3B). </li><li> Dividir o número total decélulas fluorescentes na área de não-electroporado pelo número de células electroporadas ao longo da borda (Figuras 3A e 3B). NOTA: A transferência de, pelo menos, 200 células de fronteira electroporadas contíguos é calculado para cada experiência. O valor obtido é o valor CIJH. </li></ol>

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The corresponding author is the inventor in a patent held by Queen&#8217;s University, which has been licensed to Cell Projects Inc. The company or the University had no influence upon the contents of the paper.

As etapas críticas no protocolo Material de electroporados A pureza do material a ser electroporada é muito importante. Se as células são muito plana, então as concentrações mais elevadas do corante de rastreio devem ser usados ​​(até 20 mg / ml para LY) e em tais casos, a pureza é mais importante do que em células com uma forma mais esférica 1. Além LY uma grande variedade de outros corantes ou moléculas nonpermeant têm sido empregues, tais...

A aplicação de corrente eléctrica para uma célula provoca a formação de poros na membrana da célula, por um processo denominado electroporação. Os poros permitem a passagem de uma variedade de moléculas nonpermeant através da membrana. O campo eléctrico pode ser controlada com precisão, de modo a que os poros que se formam são muito pequenas e religar-se rapidamente, com uma perturbação mínima para a fisiologia celular. Interessantemente, as células aderentes podem ser cultivadas numa lâmina de vidro revestido com óxido de índio-estanho condutora e transparente (ITO) e electroporado in situ, isto é sobre a superfície de onde elas crescem, sem ser retirado para ser electroporada em suspensão. As células podem crescer muito bem nesta superfície, e como eles estão ligados e ampliado, a observação microscópica detalhada é possível. Utilizando esta técnica, as pequenas moléculas nonpermeant pode ser introduzido imediatamente e essencialmente em 100% das células, o que faz com que esta técnica especialmente adequado para estudos sobre a activação do components de um caminho a seguir a estimulação do ligando de um receptor (revisto em 1). A electroporação foi usado principalmente para a introdução de ADN (também chamada electrotransfection). No entanto, a electroporação in situ pode ser valiosa para a introdução de uma grande variedade de moléculas, tais como péptidos 2-4, oligonucleótidos, tais como ARN anti-sentido, oligonucleótidos de cadeia dupla de DNA de engodo para inibir a ligação do factor de transcrição, ou siRNA 3,5, 6, nucleotídeos radioativos 7-10, proteínas 11 12 ou pró-drogas 13. Após a electroporação, as células podem ser lisadas para análise bioquímica ou fixadas e coradas com anticorpos. O revestimento condutor de ITO é muito fina, 800-1,000Å, de modo que o crescimento celular não é perturbado pela diferença em altura das duas superfícies, como as células crescem em toda a borda do revestimento condutor. Isto oferece a vantagem de que não electropAs células podem ser cultivadas orated lado a lado com os electroporadas, para servir como controlos. A mesma abordagem pode ser usada para o exame de junções de hiato, a comunicação intercelular (CIJH), como descrito no vídeo. Junções comunicantes são canais que ligam o interior das células adjacentes 14. Das junções de hiato, a comunicação intercelular desempenha um papel importante na formação de tumores e metástases, enquanto que os oncogenes tais como Src suprimir CIJH 15,16. Para examinar a CIJH um corante fluorescente, tal como amarelo Lucifer (LY) é muitas vezes introduzido em células cultivadas através de microinjecção ou raspar-carregamento 17 e a difusão do corante para as células vizinhas é observada microscopicamente sob luz de fluorescência. Estas técnicas contudo invariavelmente causar dano celular. Descreve-se agora uma técnica em que as células são cultivadas sobre uma lâmina de vidro, que é parcialmente revestida com ITO 18. Um impulso eléctrico foi aplicada na presença de LY (ou outros corantes) cautilizando a sua penetração nas células que crescem na parte condutora da lâmina, enquanto que a migração do corante para as células adjacentes, não electroporadas foi observada microscopicamente através de iluminação de fluorescência. Para evitar as células sensíveis perturbadores que possam tender a separar da monocamada, foi concebido um conjunto que não requerem um eléctrodo a ser colocado no topo das células para aplicar a corrente eléctrica 19. Esta abordagem oferece a possibilidade de quantificar a CIJH em ​​um grande número de células, sem qualquer perturbação detectável para o metabolismo celular, como indicado pela ausência de um efeito sobre a duração da fase G1 seguindo estimulação sérica 12, em aumentar os níveis de fos proteína proto-oncogene (Raptis, não publicado) ou duas quinases associadas ao estresse celular, o porco p38 ou JNK / SAPK quinase 1. Esta abordagem possibilitou a análise da relação entre os níveis de oncogene expressão, transformação e GJIC 18, bem como o efeito da Src e Stat3 sobre CIJH em ​​uma variedade de tipos de células, incluindo as células cultivadas de fresco a partir de espécimes de tumor de pulmão de 20-23. Além disso, em electroporação in situ com a configuração descrita, a qual não tem um eléctrodo de topo tem sido empregue com sucesso para a demonstração de fecho das junções de hiato na diferenciação dos adipócitos, embora a adesão celular ao substrato é reduzido, nessa fase, 19,24.

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			<td height="42" style="height:42px;width:179px;">Name of Material/ Equipment</td>
			<td style="width:428px;">Company</td>
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			<td style="width:167px;">Comments/Description</td>
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			<td height="21" style="height:21px;width:179px;">DMEM</td>
			<td style="width:428px;">Cellgro http://www.cellgro.com/</td>
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			<td height="21" style="height:21px;width:179px;">DMEM without Calcium</td>
			<td style="width:428px;">Hyclone (Thermo scientific: http://www.thermoscientific.com)</td>
			<td style="width:119px;">SH30319-01</td>
			<td></td>
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			<td height="21" style="height:21px;width:179px;">Donor Calf Serum&#160;</td>
			<td style="width:428px;">PAA: http://www.paa.com/</td>
			<td style="width:119px;">Cat.# B15-008</td>
			<td></td>
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			<td height="21" style="height:21px;width:179px;">Fetal Bovine Serum</td>
			<td style="width:428px;">PAA: http://www.paa.com/</td>
			<td style="width:119px;">Cat.# A15-751</td>
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			<td height="21" style="height:21px;width:179px;">Electroporation apparatus</td>
			<td style="width:428px;">Cell Projects Ltd UK: http://www.cellprojects.com/</td>
			<td style="width:119px;">ACE-100</td>
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			<td height="21" style="height:21px;width:179px;">Chambers</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
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			<td>4-wells</td>
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			<td height="21" style="height:21px;width:179px;">Chambers</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
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			<td>8-wells</td>
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			<td height="21" style="height:21px;width:179px;">Lucifer Yellow</td>
			<td style="width:428px;">Cell Projects Ltd UK</td>
			<td style="width:119px;">ACE-25-LY</td>
			<td>High purity</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">CelTak</td>
			<td style="width:428px;">BD Biosciences</td>
			<td style="width:119px;">354240</td>
			<td>Cell and tissue adhesive</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Fibronectin</td>
			<td style="width:428px;">Sigma Aldrich</td>
			<td style="width:119px;">F1141</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:179px;">Collagen</td>
			<td style="width:428px;">BD Biosciences</td>
			<td style="width:119px;">354236</td>
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			<td height="21" style="height:21px;width:179px;">Poly-Lysine</td>
			<td style="width:428px;">Sigma Aldrich</td>
			<td style="width:119px;">P8920</td>
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a functional assay for gap junctional examination; electroporation of adherent cells on indium-tin oxide

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. A variety of molecules, such as peptides or oligonucleotides can be introduced into essentially 100% of the cells in a non-traumatic manner.&#160; Here, we describe how it can be used to study intercellular, gap junctional communication. Lucifer yellow penetrates into the cells when an electric pulse, applied to the conductive surface on which they are growing, causes pores to form through the cell membrane. This is electroporation. Cells growing on the nonconductive&#160;glass surface immediately adjacent to the electroporated region do not take up Lucifer yellow by electroporation but do acquire the fluorescent dye as it is passed to them via gap junctions that link them to the electroporated cells. The results of the transfer of dye from cell to cell can be observed microscopically under fluorescence illumination. This technique allows for precise quantitation of gap junctional communication. In addition, it can be used for the introduction of peptides or other non-permeant molecules, and the transfer of small electroporated peptides via gap junctions to inhibit the signal in the adjacent, non-electroporated cells is a powerful demonstration of signal inhibition.

A Figura 2 mostra as células epiteliais de fígado de rato 22 T51B, electroporadas com LY e fotografadas sob fluorescência (painel A e B) ou de contraste de fase (C), na sequência de fixação de iluminação e de lavar roupa. No painel A, a borda da área de electroporação é marcado a vermelho. O gradiente de fluorescência para a direita da linha vermelha indica a transferência através de junções de hiato. Na Figura 3A e 3B, a quantificação da c...

Watch this Scientific Journal Video about A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide at JoVE.com

A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

This presentation demonstrates a method whereby electroporation of adherent, cultured cells is used for the study of intercellular, junctional communication, while the cells grow on a slide coated with conductive and transparent indium-tin oxide.

Um ensaio funcional para juncional Exame; Eletroporação de aderentes em células no Índio-Tin Oxide

In this technique, cells are cultured on a glass slide that is partly coated with indium-tin oxide (ITO), a transparent, electrically conductive material. ...

a-functional-assay-for-gap-junctional-examination-electroporation

Research

JoVE Journal

Biology

9.8K visualizações.  Queen's University. This presentation demonstrates a method whereby electroporation of adherent, cultured cells is used for the study of intercellular, junctional communication, while the cells grow on a slide coated with conductive and transparent indium-tin oxide.

Vídeo: A Functional Assay for Gap Junctional Examination; Electroporation of Adherent Cells on Indium-Tin Oxide

Patterning Cells on Optically Transparent Indium Tin Oxide Electrodes

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular constructs serving as in vitro mimics of native tissues.  In this study, photolithography and wet etching techniques were used to fabricate individually addressable indium tin oxide (ITO) electrodes on glass substrates.  The glass substrates containing ITO microelectrodes were modified with poly(ethylene glycol) (PEG) silane to make them protein and cell resistive.  Presence of insulating PEG molecules on the electrode surface was verified by cyclic voltammetry employing potassium ferricyanide as a redox reporter molecule.  Importantly, the application of reductive potential caused desorption of the PEG layer, resulting in regeneration of the conductive electrode surface and appearance of typical ferricyanide redox peaks.    Application of reductive potential also corresponded to switching of ITO electrode properties from cell non-adhesive to cell-adhesive. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.  Micropatterning of several cell types was demonstrated on these substrates.   In the future, the control of the biointerfacial properties afforded by this method will allow to engineer cellular microenvironments through the assembly of three or more cell types into a precise geometric configuration on an optically transparent substrate.

Non-fouling PEG silane monolayer was desorbed from individually addressable ITO electrodes on glass by application of a reductive potential. Electrochemical stripping of PEG-silane layer from ITO microelectrodes allowed for cell adhesion to take place in a spatially defined fashion, with cellular patterns corresponding closely to electrode patterns.

Células padronização na opticamente transparentes Indium Tin Oxide Eletrodos

The ability to exercise precise spatial and temporal control over cell-surface interactions is an important prerequisite to the assembly of multi-cellular ...

Biologia

Labeling hESCs and hMSCs with Iron Oxide Nanoparticles for Non-Invasive in vivo Tracking with MR Imaging

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative medicine. A non-invasive method to monitor the transplanted stem cells repeatedly in vivo would greatly enhance our ability to understand the mechanisms that control stem cell death and identify trophic factors and signaling pathways that improve stem cell engraftment. MR imaging has been proven to be an effective tool for the in vivo depiction of stem cells with near microscopic anatomical resolution. In order to detect stem cells with MR, the cells have to be labeled with cell specific MR contrast agents. For this purpose, iron oxide nanoparticles, such as superparamagnetic iron oxide particles (SPIO), are applied, because of their high sensitivity for cell detection and their excellent biocompatibility. SPIO particles are composed of an iron oxide core and a dextran, carboxydextran or starch coat, and function by creating local field inhomogeneities, that cause a decreased signal on T2-weighted MR images. This presentation will demonstrate techniques for labeling of stem cells with clinically applicable MR contrast agents for subsequent non-invasive in vivo tracking of the labeled cells with MR imaging.

For the evaluation of new stem cell therapies it is important to non-invasively track the injected cells in vivo. This video will show you how to label human mesenchymal and embryonic stem cells with iron oxide based contrast agents in vivo for subsequent MR imaging in vivo.

Rotulagem e hESCs hMSCs com óxido de ferro nanopartículas para Não-invasiva em Rastreamento vivo com ressonância magnética

In recent years, stem cell research has led to a better understanding of developmental biology, various diseases and its potential impact on regenerative ...

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell differentiation, axon guidance, retinotopic organization and synapse formation[1]. One drawback is the inability to efficiently and reliably manipulate gene expression in RGCs in vivo, especially in the otherwise accessible murine visual pathways. Transgenic mice can be used to manipulate gene expression, but this approach is often expensive, time consuming, and can produce unwanted side effects. In chick, in ovo electroporation is used to manipulate gene expression in RGCs for examining retina and RGC development. Although similar electroporation techniques have been developed in neonatal mouse pups[2], adult rats[3], and embryonic murine retinae in vitro[4], none of these strategies allow full characterization of RGC development and axon projections in vivo. To this end, we have developed two applications of electroporation, one in utero and the other ex vivo, to specifically target embryonic murine RGCs[5, 6]. 
With in utero retinal electroporation, we can misexpress or downregulate specific genes in RGCs and follow their axon projections through the visual pathways in vivo, allowing examination of guidance decisions at intermediate targets, such as the optic chiasm, or at target regions, such as the lateral geniculate nucleus. Perturbing gene expression in a subset of RGCs in an otherwise wild-type background facilitates an understanding of gene function throughout the retinal pathway. Additionally, we have developed a companion technique for analyzing RGC axon growth in vitro. We electroporate embryonic heads ex vivo, collect and incubate the whole retina, then prepare explants from these retinae several days later. Retinal explants can be used in a variety of in vitro assays in order to examine the response of electroporated RGC axons to guidance cues or other factors. In sum, this set of techniques enhances our ability to misexpress or downregulate genes in RGCs and should greatly aid studies examining RGC development and axon projections.

In utero and ex vivo Electroporation for Gene Expression in Mouse Retinal Ganglion Cells

Here we present two techniques for manipulating gene expression in murine retinal ganglion cells (RGCs) by in utero and ex vivo electroporation. These techniques enable one to examine how alterations in gene expression affect RGC development, axon guidance, and functional properties.

No útero e ex eletroporação in vivo para Expressão Gênica em células ganglionares da retina do rato

The retina and its sole output neuron, the retinal ganglion cell (RGC), comprise an excellent model in which to examine biological questions such as cell ...

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells

Protein function is intimately coupled to protein localization. Although some proteins are restricted to a specific location or subcellular compartment, many proteins are present as a freely diffusing population in free exchange with a sub-population that is tightly associated with a particular subcellular domain or structure. In situ subcellular fractionation allows the visualization of protein compartmentalization and can also reveal protein sub-populations that localize to specific structures. For example, removal of soluble cytoplasmic proteins and loosely held nuclear proteins can reveal the stable association of some transcription factors with chromatin. Subsequent digestion of DNA can in some cases reveal association with the network of proteins and RNAs that is collectively termed the nuclear scaffold or nuclear matrix. 
Here we describe the steps required during the in situ fractionation of adherent and non-adherent mammalian cells on microscope coverslips. Protein visualization can be achieved using specific antibodies or fluorescent fusion proteins and fluorescence microscopy. Antibodies and/or fluorescent dyes that act as markers for specific compartments or structures allow protein localization to be mapped in detail. In situ fractionation can also be combined with western blotting to compare the amounts of protein present in each fraction. This simple biochemical approach can reveal associations that would otherwise remain undetected.

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells

In situ subcellular fractionation of mammalian cells on microscope coverslips allows the visualisation of protein localisation.

Fracionamento em Subcelulares situ de aderentes e não aderentes células de mamíferos

Protein function is intimately coupled to protein localization. Although some proteins are restricted to a specific location or subcellular compartment, ...

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying potassium (referred to as GIRK) channels, which are important for regulating the excitability of neurons. There are four different mammalian GIRK channel subunits (GIRK1-GIRK4) - we focus on GIRK2 because it forms a homotetramer. Stimulation of different types of G protein-coupled receptors (GPCRs), such as the muscarinic receptor (M2R), leads to activation of GIRK channels. Alcohol also directly activates GIRK channels. We will show how to mutate one amino acid by specifically changing one or more nucleotides in the cDNA for the GIRK channel. This mutated cDNA sequence will be amplified in bacteria, purified, and the presence of the point mutation will be confirmed by DNA sequencing. The cDNAs for the mutated and wild-type GIRK channels will be transfected into human embryonic kidney HEK293T cells cultured in vitro. Lastly, whole-cell patch-clamp electrophysiology will be used to study the macroscopic potassium currents through the ectopically expressed wild-type or mutated GIRK channels. In this experiment, we will examine the effect of a L257W mutation in GIRK2 channels on M2R-dependent and alcohol-dependent activation.

We will demonstrate how to study the effect of a single point mutation on the function of an ion channel.

Mutagênese e Análise Funcional de canais iônicos Heterologously Expresso em células de mamíferos

We will demonstrate how to study the functional effects of introducing a point mutation in an ion channel. We study G protein-gated inwardly rectifying ...

Clonogenic Assay: Adherent Cells

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture1. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811)2. Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant formulation.

The applicability of the clonogenic assay for evaluating reproductive viability has been established for more than 50 years. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cells.

Clonogênica Ensaio: células aderentes

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. ...

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3'UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes. More than 700 human miRNAs have been identified so far with each having up to hundreds of unique target mRNAs. Computational tools, expression and proteomics assays, and chromatin-immunoprecipitation-based techniques provide important clues for identifying mRNAs that are direct targets of a particular miRNA. In addition, 3'UTR-reporter assays have become an important component of thorough miRNA target studies because they provide functional evidence for and quantitate the effects of specific miRNA-3'UTR interactions in a cell-based system. To enable more researchers to leverage 3'UTR-reporter assays and to support the scale-up of such assays to high-throughput levels, we have created a genome-wide collection of human 3'UTR luciferase reporters in the highly-optimized LightSwitch Luciferase Assay System. The system also includes synthetic miRNA target reporter constructs for use as positive controls, various endogenous 3'UTR reporter constructs, and a series of standardized experimental protocols.
Here we describe a method for co-transfection of individual 3'UTR-reporter constructs along with a miRNA mimic that is efficient, reproducible, and amenable to high-throughput analysis.

Identifying Targets of Human microRNAs with the LightSwitch Luciferase Assay System using 3&#039;UTR-reporter Constructs and a microRNA Mimic in Adherent Cells

MicroRNAs (miRNAs) are important regulators of gene expression and have been shown to play a role in numerous biological processes. To better understand miRNA-UTR interactions, we have created a genome-wide collection of 3 UTR luciferase reporters paired with a novel luciferase gene and assay reagent, the LightSwitch system.

Metas de identificação de microRNAs humanos com o Sistema de ensaio de luciferase lightswitch usando 3&#39;UTR repórter-Constrói e um microRNA em células aderentes Mimic

MicroRNAs (miRNAs) are important regulators of gene expression and play a role in many biological processes.  More than 700 human miRNAs have been ...

Examination of Drosophila Larval Tracheal Terminal Cells by Light Microscopy

Cell shape is critical for cell function. However, despite the importance of cell morphology, little is known about how individual cells generate specific shapes. Drosophila tracheal terminal cells have become a powerful genetic model to identify and elucidate the roles of genes required for generating cellular morphologies. Terminal cells are a component of a branched tubular network, the tracheal system that functions to supply oxygen to internal tissues. Terminal cells are an excellent model for investigating questions of cell shape as they possess two distinct cellular architectures. First, terminal cells have an elaborate branched morphology, similar to complex neurons; second, terminal cell branches are formed as thin tubes and contain a membrane-bound intracellular lumen. Quantitative analysis of terminal cell branch number, branch organization and individual branch shape, can be used to provide information about the role of specific genetic mechanisms in the making of a branched cell. Analysis of tube formation in these cells can reveal conserved mechanisms of tubulogenesis common to other tubular networks, such as the vertebrate vasculature. Here we describe techniques that can be used to rapidly fix, image, and analyze both branching patterns and tube formation in terminal cells within Drosophila larvae. These techniques can be used to analyze terminal cells in wild-type and mutant animals, or genetic mosaics. Because of the high efficiency of this protocol, it is also well suited for genetic, RNAi-based, or drug screens in the Drosophila tracheal system.

Examination of Drosophila Larval Tracheal Terminal Cells by Light Microscopy

Here, we present a method for light microscopy analysis of tracheal terminal cells in Drosophila larvae. This method allows for quick examination of branch and lumen morphology in whole animals and would be useful for analysis of individual mutants or screens for mutations affecting terminal cell development.

Exame<em&gt; Drosophila</em&gt; Larval células terminais traqueais por microscopia de luz

Cell shape is critical for cell function. However, despite the importance of cell morphology, little is known about how individual cells generate specific ...

Measurement and Analysis of Extracellular Acid Production to Determine Glycolytic Rate

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both mitochondrial (respiration) and non-mitochondrial (other redox) reactions consume oxygen, but these reactions can be easily distinguished by chemical inhibition of mitochondrial respiration. However, while mitochondrial oxygen consumption is an unambiguous and direct measurement of respiration rate2, the same is not true for extracellular acid production and its relationship to glycolytic rate 3-6. Extracellular acid produced by cells is derived from both lactate, produced by anaerobic glycolysis, and CO2, produced in the citric acid cycle during respiration. For glycolysis, the conversion of glucose to lactate- + H+ and the export of products into the assay medium is the source of glycolytic acidification. For respiration, the export of CO2, hydration to H2CO3 and dissociation to HCO3- + H+ is the source of respiratory acidification. The proportions of glycolytic and respiratory acidification depend on the experimental conditions, including cell type and substrate(s) provided, and can range from nearly 100% glycolytic acidification to nearly 100% respiratory acidification 6. Here, we demonstrate the data collection and calculation methods needed to determine respiratory and glycolytic contributions to total extracellular acidification by whole cells in culture using C2C12 myoblast cells as a model.

Glycolysis is a defining metabolic marker in multiple biological systems. Monitoring glycolysis by measuring the extracellular flux of H+ is common, but requires correction to be quantitative and unambiguous. Here, we demonstrate how to gather and correct extracellular flux data to distinguish between respiratory and glycolytic sources of extracellular acidification.

Medição e Análise de Produção de Ácido Extracelular determinar Glicosidases Classificação

Extracellular measurement of oxygen consumption and acid production is a simple and powerful way to monitor rates of respiration and glycolysis1. Both ...

Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.

Renal injuries incurred from nephrotoxins, which include drugs ranging from antibiotics to chemotherapeutics, can result in complex disorders whose pathogenesis remains incompletely understood. This protocol demonstrates how zebrafish can be used for disease modeling of these conditions, which can be applied to the identification of renoprotective measures.

Nefrotoxina microinjeção no peixe-zebra ao modelo de lesão renal aguda

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid ...