Los becarios del Instituto Whitehead Fondos

Parte 1: ARNA etiquetado: acoplamiento de alilo amino de los tintes <ol><li> Añadir 1 g de las muestras en tubos de microcentrífuga ARNA 1,5 ml. </li><li> De vacío seca las muestras a fuego lento o no hasta que estén completamente secos. Cap cada tubo tan pronto como esté seca - no resecar! </li><li> Añadir 9μl buffer de acoplamiento para cada tubo el ARNA suavemente vortex durante 1 minuto. Centrifugar brevemente para recoger la muestra en la parte inferior del tubo, y luego dejar que la muestra se sientan en el hielo. </li><li> Añadir DMSO 22μl de alta calidad a cada tubo de Cy3 o Cy5 tinte. Un tubo de tinte es suficiente para dos muestras. El tinte Cy3 es para el etiquetado de las muestras de referencia, y el tinte Cy5 es para el etiquetado de las muestras de prueba. </li><li> Vortex los tintes para mezclar a fondo. Mantenga los tintes en la oscuridad hasta que esté listo para su uso. No prepare tinte antes de 1 hora antes de usar. Asegúrese de que no entra agua en la mezcla de tinte / DMSO en cualquier momento. </li><li> Añadir 11μl de los preparados DMSO / Cy medio de contraste para cada muestra. Mezclar bien por agitación suave. </li><li> Incubar durante 30-45 minutos a temperatura ambiente. Cubrir las muestras con papel de aluminio o de permanecer en un cajón para minimizar la exposición a la luz. </li><li> Después de la incubación, añadir 4.5μl hydroxlyamine a cada muestra para detener la reacción. Mezclar bien por agitación suave. </li><li> Incubar durante otros 15 minutos a temperatura ambiente. Cubrir las muestras con papel de aluminio o de permanecer en un cajón para minimizar la exposición a la luz. </li></ol> Parte 2: Etiquetado ARNA limpieza <ol><li> Vortex las cuentas de unión a ARN brevemente para obtener una mezcla homogénea antes de su uso. </li><li> Prepare la mezcla ARNA unión a temperatura ambiente. (Tabla 1) </li><li> Mezclar bien por agitación. </li><li> Alícuotas del tampón de elución ARNA en un tubo de 1,5 ml y se incuba a 50-60 ° C durante al menos 10 minutos. </li><li> Añadir 70μl de la mezcla de ARNA vinculante para cada muestra y mezclar bien con la pipeta hacia arriba y abajo 3-4 veces. </li><li> Transferencia de las muestras de la placa de PCR a una de 96 pozos de fondo redondo de la placa. </li><li> Añadir 50μl de 100% de isopropanol a cada muestra y mezclar bien con la pipeta hacia arriba y abajo 3-4 veces. </li><li> Agitar suavemente la placa en un agitador orbital durante por lo menos 2 minutos para mezclar bien las muestras. </li><li> Mover la placa en un soporte magnético para capturar las bolas magnéticas. Dejar la placa en el soporte hasta que la mezcla se vuelve transparente y las cuentas de enlace tienen gránulos. </li><li> Aspirar el sobrenadante cuidadosamente con una aspiradora sin molestar a los granos magnéticos. Por otra parte, retirar con cuidado el sobrenadante con una pipeta y descartar el sobrenadante. El sobrenadante debe ser de un color rosa brillante o un azul brillante en este momento debido a las moléculas de colorante no incorporado. </li><li> Retire la placa del soporte magnético. </li><li> Agregar 100μl solución de lavado ARNA a cada pocillo y agitar la placa durante 1 minuto en un agitador orbital a una velocidad moderada. Cuentas puede no dispersarse en este paso. </li><li> Mover la placa en un soporte magnético para capturar las bolas magnéticas. </li><li> Aspirar el sobrenadante cuidadosamente con una aspiradora sin molestar a los granos magnéticos. Por otra parte, retirar con cuidado el sobrenadante con una pipeta y descartar el sobrenadante. </li><li> Retire la placa del soporte magnético. </li><li> Repita el lavado de un tiempo de 2 ª con la solución de lavado 100μl ARNA. </li><li> Después del lavado 2 º, seca los granos al sacudir la placa durante 1 minuto en un agitador orbital a la velocidad máxima. No resecar las muestras! </li><li> Eluir el ARNA de las cuentas mediante la adición de 20μl Buffer precalentado elución ARNA a cada muestra. </li><li> Agite la placa para la placa en un agitador orbital durante 3 minutos, a continuación, comprobar para asegurarse de que los granos magnéticos son totalmente dispersos. Si no, continuar agitando. </li><li> Una vez que las partículas magnéticas se han dispersado totalmente, mover la placa en un soporte magnético para capturar las bolas magnéticas. El sobrenadante contiene el limpiado, etiquetados muestras Arna, y debe ser un color rosa pálido o azul pálido. </li><li> Transferir cuidadosamente la ARNA eluye a una nueva placa de PCR (o los tubos de PCR). </li><li> (Paso opcional) Comprobar la concentración de ARN y la cantidad de colorante en las muestras mediante la medición en un espectrofotómetro 1.5μl NanoDrop utilizando el módulo de microarrays. </li><li> Inmediatamente hibridar el ARNA etiquetados en una plataforma de microarrays de su elección, o, alternativamente, puede almacenar el ARNA etiquetados a -80 ° C hasta que esté listo para la hibridación. </li></ol> Tabla 1 ARNA unión Mix <table border="1"><tbody><tr><td> Reactivo </td><td> Importe para una reacción </td></tr><tr><td> * Cuentas de unión a ARN </td><td> 10μl </td></tr><tr><td> Resuspensión de bolas * Solución </td><td> 4μl </td></tr><tr><td> 100% de isopropanol ** </td><td> 6μl </td></tr><tr><td> ARNA Concentrado tampón de unión </td><td> 50μl </td></tr></tbody></table> * Mezclar los granos de unión a ARN con elcordón de solución de resuspensión primero ** Agregue el isopropanol y mezclar bien antes de añadir el concentrado de tampón de unión ARNA.

<ol>
	<li>Rubins, K. H., Hensley, L. E., Bell, G. W., Wang, C., Lefkowitz, E. J., Brown, P. O., Relman, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+analysis+of+viral+gene+expression+programs+during+poxvirus+infection:+a+transcriptional+map+of+the+vaccinia+and+monkeypox+genomes.">Comparative analysis of viral gene expression programs during poxvirus infection: a transcriptional map of the vaccinia and monkeypox genomes.</a> PLoS ONE. 3 (7), e2628-e2628 (2008).</li><li>Assarsson, E., Greenbaum, J. A., Sundstr&#246;m, M., Schaffer, L., Hammond, J. A., Pasquetto, V., Oseroff, C., Hendrickson, R. C., Lefkowitz, E. J., Tscharke, D. C., Sidney, J., Grey, H. M., Head, S. R., Peters, B., Sette, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+analysis+of+a+complete+poxvirus+transcriptome+reveals+an+immediate-early+class+of+genes.">Kinetic analysis of a complete poxvirus transcriptome reveals an immediate-early class of genes.</a> Proc. Natl. Acad. Sci. 105 (6), 2140-2145 (2008).</li><li>Satheshkumar, P. S., Moss, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poxvirus+transcriptome+analysis.">Poxvirus transcriptome analysis.</a> Proc. Natl. Acad. Sci. U.S.A. 105, E62-E62 (2008).</li><li>Assarsson, E., Greenbaum, J. A., Sundstr&#246;m, M., Schaffer, L., Hammond, J. A., Pasquetto, V., Oseroff, C., Hendrickson, R. C., Lefkowitz, E. J., Tscharke, D. C., Sidney, J., Grey, H. M., Head, S. R., Peters, B., Sette, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A.+Reply+to+Satheshkumar+and+Moss:+Poxvirus+transcriptome+analysis.">A. Reply to Satheshkumar and Moss: Poxvirus transcriptome analysis.</a> Proc. Natl. Acad. Sci. U.S.A. 105, E63-E64 (2008).</li><li>Guerra, S., L&#243;pez-Fern&#225;ndez, L. A., Pascual-Montano, A., Mu&#241;oz, M., Harshman, K., Esteban, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+gene+expression+survey+of+vaccinia+virus+infection+of+human+HeLa+cells.">Cellular gene expression survey of vaccinia virus infection of human HeLa cells.</a> J Virol. 77 (11), 6493-6506 (2003).</li><li>Guerra, S., L&#243;pez-Fern&#225;ndez, L. A., Conde, R., Pascual-Montano, A., Harshman, K., Esteban, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microarray+analysis+reveals+characteristic+changes+of+host+cell+gene+expression+in+response+to+attenuated+modified+vaccinia+virus+Ankara+infection+of+human+HeLa+cells.">Microarray analysis reveals characteristic changes of host cell gene expression in response to attenuated modified vaccinia virus Ankara infection of human HeLa cells.</a> J Virol. 78 (11), 5820-5824 (2004).</li><li>Guerra, S., L&#243;pez-Fern&#225;ndez, L. A., Pascual-Montano, A., N&#225;jera, J. L., Zaballos, A., Esteban, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Host+response+to+the+attenuated+poxvirus+vector+NYVAC:+upregulation+of+apoptotic+genes+and+NF-kappaB-responsive+genes+in+infected+HeLa+cells.">Host response to the attenuated poxvirus vector NYVAC: upregulation of apoptotic genes and NF-kappaB-responsive genes in infected HeLa cells.</a> J Virol. 80 (2), 985-998 (2006).</li><li>Guerra, S., N&#225;jera, J. L., Gonz&#225;lez, J. M., L&#243;pez-Fern&#225;ndez, L. A., Climent, N., Gatell, J. M., Gallart, T., Esteban, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+gene+expression+profiling+after+infection+of+immature+human+monocyte-derived+dendritic+cells+by+the+attenuated+poxvirus+vectors+MVA+and+NYVAC.">Distinct gene expression profiling after infection of immature human monocyte-derived dendritic cells by the attenuated poxvirus vectors MVA and NYVAC.</a> 81 (16), 8707-8721 (2007).</li></ol>

The authors have nothing to disclose.

Los pasos críticos Al realizar el acoplamiento de alilo amino, es muy importante para volver a suspender el tinte en DMSO en breve (menos de 1 hora) antes del acoplamiento y asegurarse de que no entra agua en la mezcla de tinta / DMSO, ya que reacciona con el grupo activo en el medio de contraste. No resecar el ARN (se puede secar a 1-2UL en lugar de secar por completo), y resuspender bien en el tampón de acoplamiento. Durante la reacción de acoplamiento, que la reacción en la oscuridad, c...

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<td>CyDye Post-Labeling Reactive Dye Pack</td>
<td>Reagent</td>
<td>GE Healthcare</td>
<td>RPN5661</td>
<td>Contains both Cy3 and Cy5 dyes</td>
</tr>
<tr>
<td>NanoDrop ND-1000 UV-VIS spectrophotometer</td>
<td>Other</td>
<td>NanoDrop</td>
<td>ND-1000</td>
<td>Or equivalent spectrophotometer</td>
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vaccinia virus infection &amp; temporal analysis of virus gene expression: part 3

La familia<em&gt; Poxviridae</em&gt; Se compone de grandes de doble cadena de ADN que contienen los virus que se replican exclusivamente en el citoplasma de las células infectadas. Los miembros de la<em&gt; Orthopox</em&gt; Género incluyen la viruela, el agente causante de la viruela humana, viruela de los monos, y la vaccinia (VAC), el miembro prototípico de la familia del virus. En el genoma relativamente grande (~ 200 kb) vaccinia, tres clases de genes están codificados: temprana, intermedia y tardía. Mientras que las tres clases son transcritos por la forma viral codificada ARN polimerasas, cada clase tiene una función diferente en el ciclo de vida del virus. Poxvirus utilizar múltiples estrategias para la modulación del ambiente celular del huésped durante la infección. Con el fin de entender la regulación de host y la expresión de genes del virus, hemos utilizado todo el genoma enfoques para analizar la abundancia de transcripción de los dos virus y las células huésped. Aquí, demostramos las infecciones tiempo del curso de las células HeLa con virus de la vacuna y el ARN de muestreo en varios puntos temporales después de la infección. Tanto del huésped como del ARN viral total es aislado y amplificado por la hibridación de microarrays para el análisis de la expresión génica.

Watch this Scientific Journal Video about Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 3 at JoVE.com

Vaccinia Virus Infection &amp; Temporal Analysis of Virus Gene Expression: Part 3

Protocolo de Vaccinia la infección de células HeLa y el análisis de la acogida y la expresión de genes virales. Parte 3 describe el proceso de etiquetado fluorescente del ARN amplificado de host y de muestras de virus mediante el acoplamiento de aminoácidos de alilo de los colorantes.

Infección por el virus vaccinia y Análisis temporal de la expresión génica del virus: Parte 3

The family Poxviridae consists of large double-stranded DNA containing viruses that replicate exclusively in the cytoplasm of infected cells.  Members of ...

vaccinia-virus-infection-temporal-analysis-virus-gene-expression-part

Research

JoVE Journal

Biology

8.1K vistas.  MIT - Massachusetts Institute of Technology. Protocolo de Vaccinia la infección de células HeLa y el análisis de la acogida y la expresión de genes virales. Parte 3 describe el proceso de etiquetado fluorescente del ARN amplificado de host y de muestras de virus mediante el acoplamiento de aminoácidos de alilo de los colorantes.

Video: Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 3

Bacterial Gene Expression Analysis Using Microarrays

Gen bacteriano y Análisis de Expresión El uso de microarrays

Investigación

Biología

The Preparation of Primary Hematopoietic Cell Cultures From Murine Bone Marrow for Electroporation

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell  electroporation system and Gene Pulser  electroporation buffer were specifically developed to transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells.This video demonstrates how to establish primary hematopoietic cell cultures from murine bone marrow, and then prepare them for electroporation in the MXcell system. We begin by isolating femur and tibia. Bone marrow from both femur and tibia are then harvested and cultures are established. Cultured bone marrow cells are then transfected and analyzed.

This procedure describes how to establish primary hematopoietic cell cultures from murine bone marrow and is followed by transfection using the Gene Pulser MXCell electroporation system.

La preparación de cultivos primarios de células hematopoyéticas de la médula ósea murina por electroporación

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Vaccinia Virus Infection &amp; Temporal Analysis of Virus Gene Expression: Part 1

The family Poxviridae consists of large double-stranded DNA containing viruses that replicate exclusively in the cytoplasm of infected cells. Members of the orthopox genus include variola, the causative agent of human small pox, monkeypox, and vaccinia (VAC), the prototypic member of the virus family. Within the relatively large (~ 200 kb) vaccinia genome, three classes of genes are encoded: early, intermediate, and late. While all three classes are transcribed by virally-encoded RNA polymerases, each class serves a different function in the life cycle of the virus. Poxviruses utilize multiple strategies for modulation of the host cellular environment during infection. In order to understand regulation of both host and virus gene expression, we have utilized genome-wide approaches to analyze transcript abundance from both virus and host cells. Here, we demonstrate time course infections of HeLa cells with Vaccinia virus and sampling RNA at several time points post-infection. Both host and viral total RNA is isolated and amplified for hybridization to microarrays for analysis of gene expression.

Protocol for Vaccinia infection of HeLa cells and analysis of host and viral gene expression. Part 1 of 3.

Infección por el virus vaccinia y Análisis temporal de la expresión génica del virus: Parte 1

Vaccinia Virus Infection &amp; Temporal Analysis of Virus Gene Expression: Part 2

The family Poxviridae consists of large double-stranded DNA containing viruses that replicate exclusively in the cytoplasm of infected cells. Members of the orthopox genus include variola, the causative agent of human small pox, monkeypox, and vaccinia (VAC), the prototypic member of the virus family. Within the relatively large (~ 200 kb) vaccinia genome, three classes of genes are encoded: early, intermediate, and late. While all three classes are transcribed by virally-encoded RNA polymerases, each class serves a different function in the life cycle of the virus. Poxviruses utilize multiple strategies for modulation of the host cellular environment during infection. In order to understand regulation of both host and virus gene expression, we have utilized genome-wide approaches to analyze transcript abundance from both virus and host cells. Here, we demonstrate time course infections of HeLa cells with Vaccinia virus and sampling RNA at several time points post-infection. Both host and viral total RNA is isolated and amplified for hybridization to microarrays for analysis of gene expression.

Protocol for Vaccinia infection of HeLa cells and analysis of host and viral gene expression. Part 2 of 3.

Infección por el virus vaccinia y Análisis temporal de la expresión génica del virus: Parte 2

Virus-induced Gene Silencing (VIGS) in Nicotiana benthamiana and Tomato

RNA interference (RNAi) is a highly specific gene-silencing phenomenon triggered by dsRNA1. This silencing mechanism uses two major classes of RNA regulators: microRNAs, which are produced from non-protein coding genes and short interfering RNAs (siRNAs). Plants use RNAi to control transposons and to exert tight control over developmental processes such as flower organ formation and leaf development2,3,4. Plants also use RNAi to defend themselves against infection by viruses. Consequently, many viruses have evolved suppressors of gene silencing to allow their successful colonization of their host5.
Virus-induced gene silencing (VIGS) is a method that takes advantage of the plant RNAi-mediated antiviral defense mechanism. In plants infected with unmodified viruses the mechanism is specifically targeted against the viral genome. However, with virus vectors carrying sequences derived from host genes, the process can be additionally targeted against the corresponding host mRNAs. VIGS has been adapted for high-throughput functional genomics in plants by using the plant pathogen Agrobacterium tumefaciens to deliver, via its Ti plasmid, a recombinant virus carrying the entire or part of the gene sequence targeted for silencing. Systemic virus spread and the endogenous plant RNAi machinery take care of the rest. dsRNAs corresponding to the target gene are produced and then cleaved by the ribonuclease Dicer into siRNAs of 21 to 24 nucleotides in length. These siRNAs ultimately guide the RNA-induced silencing complex (RISC) to degrade the target transcript2.
Different vectors have been employed in VIGS and one of the most frequently used is based on tobacco rattle virus (TRV). TRV is a bipartite virus and, as such, two different A. tumefaciens strains are used for VIGS. One carries pTRV1, which encodes the replication and movement viral functions while the other, pTRV2, harbors the coat protein and the sequence used for VIGS6,7. Inoculation of Nicotiana benthamiana and tomato seedlings with a mixture of both strains results in gene silencing. Silencing of the endogenous phytoene desaturase (PDS) gene, which causes photobleaching, is used as a control for VIGS efficiency. It should be noted, however, that silencing in tomato is usually less efficient than in N. benthamiana. RNA transcript abundance of the gene of interest should always be measured to ensure that the target gene has efficiently been down-regulated. Nevertheless, heterologous gene sequences from N. benthamiana can be used to silence their respective orthologs in tomato and vice versa8.

Virus-induced Gene Silencing VIGS in Nicotiana benthamiana and Tomato

Description of a virus-induced gene silencing (VIGS) method for knock-down of gene expression in Nicotiana benthamiana and tomato.

Inducida por el virus de silenciamiento génico (VIGS) en Nicotiana benthamiana Y tomate

RNA interference (RNAi) is a highly specific gene-silencing phenomenon triggered by dsRNA1. This silencing mechanism uses two major classes of RNA ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Utilizando el sistema de electroporación Gene Emisores MXcell para transfectar células primarias con alta eficiencia

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

El uso de un contador de células automatizado para simplificar estudios de expresión génica: siRNA Derribo de IL-4 la expresión génica en células dependientes Namalwa

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.
Telomerase is a specialized reverse transcriptase1 that adds short DNA repeats, called telomeres, to the 3' end of linear chromosomes2 that serve to protect them from end-to-end fusion and degradation. Following DNA replication, a short segment is lost at the end of the chromosome3 and without telomerase, cells continue dividing until eventually reaching their Hayflick Limit4. Additionally, telomerase is dormant in most somatic cells5 in adults, but is active in cancer cells6 where it promotes cell immortality7.
The minimal telomerase enzyme consists of two core components: the protein subunit (TERT), which comprises the catalytic subunit of the enzyme and an integral RNA component (TER), which contains the template TERT uses to synthesize telomeres8,9. Prior to 2008, only structures for individual telomerase domains had been solved10,11. A major breakthrough in this field came from the determination of the crystal structure of the active12, catalytic subunit of T. castaneum telomerase, TcTERT1.
Here, we present methods for producing large quantities of the active, soluble TcTERT for structural and biochemical studies, and the reconstitution of the telomerase RNP complex in vitro for telomerase activity assays. An overview of the experimental methods used is shown in Figure 1.

In vitro Reconstitution of the Active T. castaneum Telomerase

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more than a decade. Here, we present methods for the isolation of the recombinant Tribolium castaneum TERT (TcTERT) and the reconstitution of the active T. castaneum telomerase ribonucleoprotein (RNP) complex in vitro.

En la reconstitución in vitro de los activos T. castaneum telomerasa

Efforts to isolate the catalytic subunit of telomerase, TERT, in sufficient quantities for structural studies, have been met with limited success for more ...

Agrobacterium-Mediated Virus-Induced Gene Silencing Assay In Cotton

Cotton (Gossypium hirsutum) is one of the most important crops worldwide. Considerable efforts have been made on molecular breeding of new varieties. The large-scale gene functional analysis in cotton has been lagged behind most of the modern plant species, likely due to its large size of genome, gene duplication and polyploidy, long growth cycle and recalcitrance to genetic transformation1. To facilitate high throughput functional genetic/genomic study in cotton, we attempt to develop rapid and efficient transient assays to assess cotton gene functions.
Virus-Induced Gene Silencing (VIGS) is a powerful technique that was developed based on the host Post-Transcriptional Gene Silencing (PTGS) to repress viral proliferation2,3. Agrobacterium-mediated VIGS has been successfully applied in a wide range of dicots species such as Solanaceae, Arabidopsis and legume species, and monocots species including barley, wheat and maize, for various functional genomic studies3,4. As this rapid and efficient approach avoids plant transformation and overcomes functional redundancy, it is particularly attractive and suitable for functional genomic study in crop species like cotton not amenable for transformation.
In this study, we report the detailed protocol of Agrobacterium-mediated VIGS system in cotton. Among the several viral VIGS vectors, the tobacco rattle virus (TRV) invades a wide range of hosts and is able to spread vigorously throughout the entire plant yet produce mild symptoms on the hosts5. To monitor the silencing efficiency, GrCLA1, a homolog gene of Arabidopsis Cloroplastos alterados 1 gene (AtCLA1) in cotton, has been cloned and inserted into the VIGS binary vector pYL156. CLA1 gene is involved in chloroplast development6, and previous studies have shown that loss-of-function of AtCLA1 resulted in an albino phenotype on true leaves7, providing an excellent visual marker for silencing efficiency. At approximately two weeks post Agrobacterium infiltration, the albino phenotype started to appear on the true leaves, with 100% silencing efficiency in all replicated experiments. The silencing of endogenous gene expression was also confirmed by RT-PCR analysis. Significantly, silencing could potently occur in all the cultivars we tested, including various commercially grown varieties in Texas. This rapid and efficient Agrobacterium-mediated VIGS assay provides a very powerful tool for rapid large-scale analysis of gene functions at genome-wide level in cotton.

We present the detailed protocol for Agrobacterium-mediated virus-induced gene silencing (VIGS) assay in cotton. The tobacco rattle virus (TRV)-derived VIGS vectors were deployed to induce RNA silencing of cotton GrCLA1, Cloroplastos alterados 1 gene. The albino phenotype caused by silencing GrCLA1 was observed at the seedling stage within 2 weeks after inoculation.

Mediada por Agrobacterium inducida por el virus Gene ensayo silenciamiento en algodón

Cotton (Gossypium hirsutum) is one of the most important crops worldwide. Considerable efforts have been made on molecular breeding of new varieties.  The ...

The MultiBac Protein Complex Production Platform at the EMBL

Proteomics research revealed the impressive complexity of eukaryotic proteomes in unprecedented detail. It is now a commonly accepted notion that proteins in cells mostly exist not as isolated entities but exert their biological activity in association with many other proteins, in humans ten or more, forming assembly lines in the cell for most if not all vital functions.1,2 Knowledge of the function and architecture of these multiprotein assemblies requires their provision in superior quality and sufficient quantity for detailed analysis. The paucity of many protein complexes in cells, in particular in eukaryotes, prohibits their extraction from native sources, and necessitates recombinant production. The baculovirus expression vector system (BEVS) has proven to be particularly useful for producing eukaryotic proteins, the activity of which often relies on post-translational processing that other commonly used expression systems often cannot support.3 BEVS use a recombinant baculovirus into which the gene of interest was inserted to infect insect cell cultures which in turn produce the protein of choice. MultiBac is a BEVS that has been particularly tailored for the production of eukaryotic protein complexes that contain many subunits.4 A vital prerequisite for efficient production of proteins and their complexes are robust protocols for all steps involved in an expression experiment that ideally can be implemented as standard operating procedures (SOPs) and followed also by non-specialist users with comparative ease. The MultiBac platform at the European Molecular Biology Laboratory (EMBL) uses SOPs for all steps involved in a multiprotein complex expression experiment, starting from insertion of the genes into an engineered baculoviral genome optimized for heterologous protein production properties to small-scale analysis of the protein specimens produced.5-8 The platform is installed in an open-access mode at EMBL Grenoble and has supported many scientists from academia and industry to accelerate protein complex research projects.

Protein complexes catalyze key cellular functions. Detailed functional and structural characterization of many essential complexes requires recombinant production. MultiBac is a baculovirus/insect cell system particularly tailored for expressing eukaryotic proteins and their complexes. MultiBac was implemented as an open-access platform, and standard operating procedures developed to maximize its utility.

El Protein Complex Plataforma de Producción MultiBac en el EMBL

Proteomics  research revealed the impressive complexity of eukaryotic proteomes in  unprecedented detail. It is now a commonly accepted notion that ...