Las técnicas que se muestran aquí fueron desarrollados con financiación de subvenciones del Departamento de Energía (Ciencias de la Bioenergía) y la Fundación Nacional de Ciencias.

Parte 1: Crecimiento y el almacenamiento de material vegetal adecuado <ol><li> En nuestra experiencia, hipocotilos jóvenes de plántulas de pepino etioladas servir como una fuente conveniente de material de la pared celular de estos experimentos. Las semillas de pepino se siembran en papel mojado en una caja a prueba de luz, que es mantener en un armario oscuro en una sala a temperatura constante fijado en 26 ° C. La temperatura exacta no es crítica, ya que cualquier cosa entre 22 ° y 30 ° C debe estar bien, pero la temperatura va a determinar qué tan rápido las plántulas alcanzan una fase de desarrollo. Cuanto más caliente esté la temperatura, más rápido que las plántulas se desarrollan. Por lo general utilizan plantas cuando han crecido a cerca de 5 cm de longitud, que se alcanza de 3-4 días después de la siembra. Es importante que las plántulas se cultivan en la oscuridad, ya que incluso pequeñas cantidades de luz afectan tanto a la tasa de desarrollo de las plántulas y las propiedades de la pared celular que se mide con esta técnica. El día 3 se puede mirar en la caja, con una tenue luz verde filtrada, para comprobar el desarrollo de la plántula. </li><li> Las plántulas son rápidamente cortados y envasados ​​en pequeñas cajas de plástico, 100-150 plantas por caja, y se almacenan a -80 ° C. A esta temperatura siguen siendo útiles para la semana. </li></ol> Parte 2: Preparación de muestras de la pared celular <ol><li> Los grupos pequeños (8-10) de las plántulas de corte congelado se transfieren desde el congelador para un recipiente aislado que contiene un bloque de congelación -80. </li><li> La cutícula que cubre el hipocotilo se desgasta con el carburo de silicio. Esto se hace en varias ocasiones la elaboración del hipocotilo entre el pulgar y el índice, que están recubiertas con una mezcla espesa de polvo de carborundo húmedo. Se necesita un poco de experiencia para saber la cantidad correcta de presión para el uso: demasiada presión y la capa de la epidermis comienza a ser destrozado y roto, demasiado poco de presión y la cutícula no se permeabilized. Uno también tiene que trabajar con rapidez porque, como el deshielo de hipocotilo congelados, se vuelve flácida y difícil de manejar. </li><li> El hipocotilo desgastado se sumerge en agua helada para eliminar la mayoría de los carborundo adhiere y se almacena en el agua helada, mientras que el resto de hipocotilos se preparan de manera similar. </li><li> El hipocótilo se cortan a la longitud deseada, por lo general 1,2 cm, con una nueva hoja de afeitar solo filo y alineados en un portaobjetos de vidrio. </li><li> Ahora tenemos que aplanar las paredes para quitar la savia celular y para facilitar la sujeción. Una segunda lámina de vidrio se coloca en la parte superior del grupo de 8-10 muestras, formando un sandwich. Un peso (400-500 g) se coloca en la parte superior de la lámina de vidrio de 5 min. Por el peso que utilizan de forma habitual un vaso que contiene una cantidad adecuada de agua. </li><li> Paso opcional: Dependiendo del experimento, los hipocotilos puede ser inactivado con un tratamiento térmico breve en este punto. Para ello se unen las placas de vidrio junto con un par de bandas de goma, colocar el ensamblado en un recipiente con 100 ml de agua desionizada a temperatura ambiente y colóquelo en el microondas a máxima potencia. Con nuestro horno microondas el agua comienza a hervir a unos 50 s, y dejamos el microondas 15 s después de la ebullición comienza. El agua caliente se vierte rápidamente y se reemplaza con agua fría para detener la desnaturalización. Puede que tenga que modificar estos tiempos, como el horno de microondas puede ser diferente a la nuestra. Con un calentamiento excesivo de las muestras se debilitan y se rompen con facilidad. Con un calentamiento insuficiente la expansina endógeno no se inactiva y las muestras de la pared conservan la capacidad de respuesta a pH ácido. </li></ol> Parte 3: Configuración de extensómetro <ol><li> Las muestras de la pared están fijadas en un extensómetro fuerza constante. Se trata de un dispositivo de costumbre-construido que consta de una cubeta de Plexiglas para la celebración de la final de la muestra basal de la pared y una pinza móvil conectado al extremo apical de la muestra. La pinza móvil se monta en el extremo de una varilla que pasa a través de las bobinas abiertas de un sensor de posición, un LVDT o &quot;lineal transformador diferencial variable&quot;, que detecta electrónicamente la posición de un pequeño cilindro metálico, o &quot;núcleo&quot;, es decir, unido a la barra. El extremo superior de la varilla está vinculado a una palanca con un contrapeso ajustable. Esta palanca ejerce una cantidad ajustable de la fuerza hacia arriba sobre la muestra de la pared. La fuerza se ajusta mediante la adición o eliminación de calibrar pesas de metal hacia el otro extremo de la palanca. </li><li> Volver a la muestra de la pared - el extremo de la base de la muestra hipocotilo es recogido con unas pinzas finas y ~ 2.3 mm del extremo apical se sitúa entre las fauces abiertas de la mordaza móvil. Esta pinza es una pinza de cocodrilo con resorte de metal, cuya boca se cubren con plástico para evitar el contacto directo entre la superficie del metal y la solución tampón o la muestra de la pared. En nuestra experiencia de los iones metálicos pueden filtrarse de la pinza e inhiben la capacidad de la pared de extender, por lo que mantener los cubiertos de metal. </li><li> La celebración de la abrazadera móvil en una mano, el extremo de la base de la muestra de la pared es ahora maniobrar entre las dos piezas con bisagras de la cubeta de Plexiglas y la cubetapiezas se unen y se atornilla apretado, con lo que el bloqueo del extremo inferior de la muestra de la pared de la cubeta. </li><li> La mordaza móvil es ahora ligeramente en libertad, lo que permite la plena vigencia de los contrapesos que se transfiere a la muestra de la pared. Nosotros usamos un contrapeso total de 20 g para las muestras de la pared preparada a partir de hipocotilos de pepino. Otros materiales de la pared o los experimentos podrían requerir diferentes pesos. </li><li> La cubeta se llena con tampón (200 uL) y la posición de la cubeta hacia arriba o hacia abajo con un tornillo de ajuste, de modo que la pinza móvil es llevado al extremo inferior del rango de medición de LVDT. Nuestra LVDT está conectado a una unidad de adquisición de datos de una microcomputadora, por lo que controlar la posición LVDT a través del ordenador. Tenemos ocho asambleas LVDT conectado en paralelo con un ordenador, lo que nos permite ejecutar 8 muestras de la pared al mismo tiempo. La computadora registra la posición de cada uno de los conjuntos de LVDT una vez cada 30 s. </li></ol> Parte 4: Medición de la respuesta de extensión a pH ácido o expansina - Resultados de la Representante <ol><li> [Primer experimento] Para la medición de ácido inducida por extensión, comenzamos con las muestras de la pared nativos (es decir, no se inactivan con el calor) y tampón neutral se añade a la cubeta. Las muestras de la pared se extienden por unos minutos, en respuesta a la tensión añadida, pero la extensión decae a una tasa baja después de unos minutos. Nuestro equipo nos permite monitorear el cambio en la longitud de la muestra (es decir, el cambio en la posición de la pinza móvil, después del inicio del experimento) o se puede controlar la derivada de la posición, es decir, la tasa de extensión . La tasa de extensión se estabiliza en un valor bajo, con el tiempo. </li><li> Después de aproximadamente 20 minutos, el amortiguador neutral se elimina. Nosotros usamos un tubo de metal fino, hecho de una aguja hipodérmica de calibre grande, conectado a una bomba de vacío para eliminar el buffer rápidamente, con una perturbación mínima de la pared o el montaje mecánico. Tampón ácido se añade, a veces con 1-2 intercambios rápidos para asegurar el intercambio completo de tampón ácido. Entonces sentarse y ver la respuesta de la pared. Por lo general se puede detectar la velocidad más rápida de la extensión en pocos minutos. Después de 60 minutos por lo general tienen suficiente información para evaluar la respuesta de extensión, aunque en algunos casos, las medidas pueden extenderse a periodos más largos. </li><li> [Segundo experimento] Para la medición de expansina inducida por la extensión de la pared celular, se comienza con las muestras de la pared inactivado por calor y tampón ácido se añade a la cubeta. Al igual que en el primer experimento, la tasa de extensión de la pared celular poco a poco se estabiliza en un valor bajo debido a la falta de expansina funcional. </li><li> Después de aproximadamente 20 min, las proteínas expansina se añade a la cubeta de &#39;picos&#39; de la memoria intermedia en la cubeta con 10-20 l de una solución expansina. El expansina penetra rápidamente en la muestra de la pared celular y en pocos minutos, vemos que la tasa de extensión se ha incrementado. Esta respuesta de la extensión puede ser seguido por una hora o más. </li></ol><img src="/files/ftp_upload/1263/fig1.png" alt="" width="600" height="469" /> Figura 1: Esquema de los procedimientos para la preparación de las paredes celulares para evaluar inducida por el ácido o expansina inducida por la extensión de la pared.

<ol>
	<li>Cosgrove, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+long-term+extension+of+isolated+cell+walls+from+growing+cucumber+hypocotyls.">Characterization of long-term extension of isolated cell walls from growing cucumber hypocotyls.</a> Planta. 177, 121-130 (1989).</li><li>Rayle, D. L., Cleland, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Acid+Growth+Theory+of+auxin-induced+cell+elongation+is+alive+and+well.">The Acid Growth Theory of auxin-induced cell elongation is alive and well.</a> Plant Physiol. 99, 1271-1274 (1992).</li><li>Cleland, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auxin-induced+growth+of+Avena+coleoptiles+involves+two+mechanisms+with+different+pH+optima.">Auxin-induced growth of Avena coleoptiles involves two mechanisms with different pH optima.</a> Plant Physiol. 99, 1556-1561 (1992).</li><li>Cosgrove, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loosening+of+plant+cell+walls+by+expansins.">Loosening of plant cell walls by expansins.</a> Nature. 407, 321-326 (2000).</li><li>McQueen-Mason, S., Durachko, D. M., Cosgrove, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+endogenous+proteins+that+induce+cell+wall+expansion+in+plants.">Two endogenous proteins that induce cell wall expansion in plants.</a> Plant Cell. 4, 1425-1433 (1992).</li></ol>

Para esta demostración se utilizó las paredes celulares de hipocotilos de pepino, ya que han demostrado ser una fuente confiable de las muestras de la pared que son fáciles de manejar y que responden con buena sensibilidad. También hemos tenido mucho éxito con las paredes de las plántulas, así como otros materiales de algunos de los supermercados, tales como hojas de espinacas jóvenes y tallos de apio. Básicamente, el joven, suave y rápido crecimiento de los tejidos vegetales es probable que sean fáciles de m...

measuring plant cell wall extension (creep) induced by acidic ph and by alpha-expansin

Cada vez las paredes celulares vegetales típicamente presentan una propiedad conocida como &quot;el crecimiento de ácido, por lo que entendemos que es más extensible a un pH bajo (&lt;5) 1. La hormona auxina planta rápidamente estimula la elongación celular en los tallos jóvenes y los tejidos similares al menos en parte por un mecanismo ácido-crecimiento del 2, 3. Auxina activa una bomba de H + en la membrana plasmática, provocando la acidificación de la solución de la pared celular. La acidificación de la pared activa expansins, que son endógena de desprendimiento de la pared de las proteínas 4, haciendo que la pared celular a ceder a las tensiones creadas por la presión de la pared celular de turgencia. Como resultado, la célula comienza a crecer rápidamente. Este fenómeno de crecimiento de ácido &#39;se mide fácilmente en el aislamiento (no vivos) muestras de la pared celular. La capacidad de las paredes de las células a sufrir inducida por el ácido de extensión no es simplemente el resultado de la disposición estructural de los polisacáridos de la pared celular (pectinas, por ejemplo), pero depende de la actividad de expansins 5. Expansinas no tienen actividad enzimática conocida y la única manera de ensayo para la actividad expansina es medir su inducción de la extensión de la pared celular. Este informe de detalles del vídeo de las fuentes y técnicas de preparación para la obtención de materiales adecuados para los ensayos de la pared expansina y pasa a mostrar inducida por el ácido de extensión y expansina inducida por la extensión de las muestras de la pared preparada a partir de hipocotilos de pepino en crecimiento. Para obtener muestras adecuadas de la pared celular, las plántulas de pepino se cultiva en la oscuridad, los hipocotilos se cortan y se congelan a -80 ° C. Hipocotilos congelados son desgastado, aplastado, y sujeta a una tensión constante en una cubeta especial para la medición del extensómetro. Para medir la inducida por el ácido de extensión, las paredes están inicialmente tamponada a pH neutro, lo que resulta en una baja actividad de expansins que son componentes de las paredes celulares de origen. Tras el intercambio de buffer de pH ácido, expansins se activan y las paredes celulares se extienden rápidamente. También demuestran una actividad expansina en un ensayo de reconstitución. Para esta parte, se utiliza un tratamiento térmico breve para desnaturalizar el expansins nativos en las muestras de la pared celular. Estas paredes de las células inactivadas no se dan incluso en tampón ácido, pero la adición de expansins de las paredes celulares rápidamente recupera su capacidad de extender.

Watch this Scientific Journal Video about Measuring Plant Cell Wall Extension Creep Induced by Acidic pH and by Alpha-Expansin at JoVE.com

Measuring Plant Cell Wall Extension Creep Induced by Acidic pH and by Alpha-Expansin

Se demuestra el uso de un extensómetro de fuerza constante a medida a largo plazo de extensión (fluencia) de especímenes de plantas de la pared celular inducida por tampones ácidos y proteínas expansina.

Celda de medición Planta de Extensión de la pared (creep) inducida por el pH ácido y por Alfa-expansina

Growing plant cell walls characteristically exhibit a property known as 'acid growth', by which we mean they are more extensible at low pH (&lt; 5) 1. The ...

measuring-plant-cell-wall-extension-creep-induced-acidic-ph-alpha

Research

JoVE Journal

Biology

Measuring Plant Cell Wall Extension (Creep) Induced by Acidic pH and by Alpha-Expansin

13.9K vistas.  Penn State University. Se demuestra el uso de un extensómetro de fuerza constante a medida a largo plazo de extensión (fluencia) de especímenes de plantas de la pared celular inducida por tampones ácidos y proteínas expansina.

Video: Measuring Plant Cell Wall Extension Creep Induced by Acidic pH and by Alpha-Expansin

Title Cell Encapsulation by Droplets

Título encapsulación celular a través de gotitas

Investigación

Biología

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 ...

Identification of Growth Inhibition Phenotypes Induced by Expression of Bacterial Type III Effectors in Yeast

Many Gram-negative pathogenic bacteria use a type III secretion system to translocate a suite of effector proteins into the cytosol of host cells. Within the cell, type III effectors subvert host cellular processes to suppress immune responses and promote pathogen growth. Numerous type III effectors of plant and animal bacterial pathogens have been identified to date, yet only a few of them are well characterized. Understanding the functions of these effectors has been undermined by a combination of functional redundancy in the effector repertoire of a given bacterial strain, the subtle effects that they may exert to increase virulence, roles that are possibly specific to certain infection stages, and difficulties in genetically manipulating certain pathogens. Expression of type III effectors in the budding yeast Saccharomyces cerevisiae may allow circumventing these limitations and aid to the functional characterization of effector proteins. Because type III effectors often target cellular processes that are conserved between yeast and other eukaryotes, their expression in yeast may result in growth inhibition phenotypes that can be exploited to elucidate effector functions and targets. Additional advantages to using yeast for functional studies of bacterial effectors include their genetic tractability, information on predicted functions of the vast majority of their ORFs, and availability of numerous tools and resources for both genome-wide and small-scale experiments. Here we discuss critical factors for designing a yeast system for the expression of bacterial type III effector proteins. These include an appropriate promoter for driving expression of the effector gene(s) of interest, the copy number of the effector gene, the epitope tag used to verify protein expression, and the yeast strain. We present procedures to induce expression of effectors in yeast and to verify their expression by immunoblotting. In addition, we describe a spotting assay on agar plates for the identification of effector-induced growth inhibition phenotypes. The use of this protocol may be extended to the study of pathogenicity factors delivered into the host cell by any pathogen and translocation mechanism.

In this video, we describe a procedure for the expression of bacterial type III effectors in yeast and the identification of effector-induced growth inhibition phenotypes. Such phenotypes can be subsequently exploited to elucidate effector functions and targets.

Identificación de los fenotipos de inhibición del crecimiento inducida por la expresión de tipo bacteriana efectores III en la levadura

Many Gram-negative pathogenic bacteria use a type III secretion system to translocate a suite of effector proteins into the cytosol of host cells. Within ...

Agar-Block Microcosms for Controlled Plant Tissue Decomposition by Aerobic Fungi

The two principal methods for studying fungal biodegradation of lignocellulosic plant tissues were developed for wood preservative testing (soil-block; agar-block). It is well-accepted that soil-block microcosms yield higher decay rates, fewer moisture issues, lower variability among studies, and higher thresholds of preservative toxicity. Soil-block testing is thus the more utilized technique and has been standardized by American Society for Testing and Materials (ASTM) (method D 1413-07). The soil-block design has drawbacks, however, using locally-variable soil sources and in limiting the control of nutrients external (exogenous) to the decaying tissues. These drawbacks have emerged as a problem in applying this method to other, increasingly popular research aims. These modern aims include degrading lignocellulosics for bioenergy research, testing bioremediation of co-metabolized toxics, evaluating oxidative mechanisms, and tracking translocated elements along hyphal networks. Soil-blocks do not lend enough control in these applications. A refined agar-block approach is necessary.
Here, we use the brown rot wood-degrading fungus Serpula lacrymans to degrade wood in agar-block microcosms, using deep Petri dishes with low-calcium agar. We test the role of exogenous gypsum on decay in a time-series, to demonstrate the utility and expected variability. Blocks from a single board rip (longitudinal cut) are conditioned, weighed, autoclaved, and introduced aseptically atop plastic mesh. Fungal inoculations are at each block face, with exogenous gypsum added at interfaces. Harvests are aseptic until the final destructive harvest. These microcosms are designed to avoid block contact with agar or Petri dish walls. Condensation is minimized during plate pours and during incubation. Finally, inoculum/gypsum/wood spacing is minimized but without allowing contact. These less technical aspects of agar-block design are also the most common causes of failure and the key source of variability among studies. Video publication is therefore useful in this case, and we demonstrate low-variability, high-quality results.

This video demonstrates a controlled environment approach to study degradation of lignocellulosic plant tissues by aerobic fungi. The ability to control nutrient sources and moisture is a key advantage of agar-block microcosms, but the approach often yields mixed success. We address critical pitfalls to yield reproducible, low-variability results.

Bloque de agar-microcosmos de descomposición controlada de Tejidos Vegetales de hongos aerobios

The two principal methods for studying fungal biodegradation of lignocellulosic plant tissues were developed for wood preservative testing (soil-block; ...

Pouring and Running a Protein Gel by reusing Commercial Cassettes

The evaluation of proteins using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis is a common technique used by biochemistry and molecular biology researchers1-4. For laboratories that perform daily analyses of proteins, the cost of commercially available polyacrylamide gels (&tilde;$10/gel) can be considerable over time. To mitigate this cost, some researchers prepare their own polyacrylamide gels. Traditional methods of pouring these gels typically utilize specialized equipment and glass gel plates that can be expensive and preclude pouring many gels and storing them for future use. Furthermore, handling of glass plates during cleaning or gel pouring can result in accidental breakage creating a safety hazard, which may preclude their use in undergraduate laboratory classes. Our protocol demonstrates how to pour multiple protein gels simultaneously by recycling Invitrogen Nupage Novex minigel cassettes, and inexpensive materials purchased at a home improvement store. This economical and streamlined method includes a way to store the gels at 4&deg;C for a few weeks. By re-using the plastic gel cassettes from commercially available gels, labs that run frequent protein gels can save significant costs and help the environment. In addition, plastic gel cassettes are extremely resistant to breakage, which makes them ideal for undergraduate laboratory classrooms.

Our protocol demonstrates how to pour multiple protein gels at a time by recycling Invitrogen Nupage Novex minigel cassettes, and inexpensive materials purchased at a home improvement store. This economical and streamlined method includes a way to store the gels at 4&deg;C for a few weeks. By re-using the plastic gel cassettes from commercially available gels, labs that run frequent protein gels can save significant costs and help the environment.

Verter y ejecución de un gel de proteínas mediante la reutilización de casetes comerciales

The evaluation of proteins using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis is a common technique used by biochemistry ...

Glycan Profiling of Plant Cell Wall Polymers using Microarrays

Plant cell walls are complex matrixes of heterogeneous glycans which play an important role in the physiology and development of plants and provide the raw materials for human societies (e.g. wood, paper, textile and biofuel industries)1,2. However, understanding the biosynthesis and function of these components remains challenging.
Cell wall glycans are chemically and conformationally diverse due to the complexity of their building blocks, the glycosyl residues. These form linkages at multiple positions and differ in ring structure, isomeric or anomeric configuration, and in addition, are substituted with an array of non-sugar residues. Glycan composition varies in different cell and/or tissue types or even sub-domains of a single cell wall3. Furthermore, their composition is also modified during development1, or in response to environmental cues4.
In excess of 2,000 genes have Plant cell walls are complex matrixes of heterogeneous glycans been predicted to be involved in cell wall glycan biosynthesis and modification in Arabidopsis5. However, relatively few of the biosynthetic genes have been functionally characterized 4,5. Reverse genetics approaches are difficult because the genes are often differentially expressed, often at low levels, between cell types6. Also, mutant studies are often hindered by gene redundancy or compensatory mechanisms to ensure appropriate cell wall function is maintained7. Thus novel approaches are needed to rapidly characterise the diverse range of glycan structures and to facilitate functional genomics approaches to understanding cell wall biosynthesis and modification.
Monoclonal antibodies (mAbs)8,9 have emerged as an important tool for determining glycan structure and distribution in plants. These recognise distinct epitopes present within major classes of plant cell wall glycans, including pectins, xyloglucans, xylans, mannans, glucans and arabinogalactans. Recently their use has been extended to large-scale screening experiments to determine the relative abundance of glycans in a broad range of plant and tissue types simultaneously9,10,11.
Here we present a microarray-based glycan screening method called Comprehensive Microarray Polymer Profiling (CoMPP) (Figures 1 &amp; 2)10,11 that enables multiple samples (100 sec) to be screened using a miniaturised microarray platform with reduced reagent and sample volumes. The spot signals on the microarray can be formally quantified to give semi-quantitative data about glycan epitope occurrence. This approach is well suited to tracking glycan changes in complex biological systems12 and providing a global overview of cell wall composition particularly when prior knowledge of this is unavailable.

A technique called Comprehensive Microarray Polymer Profiling (CoMPP) for the characterisation of plant cell wall glycans is described. This method combines the specificity of monoclonal antibodies directed to defined glycan-epitopes with a miniature microarray analytical platform allowing screening of glycan occurrence in a broad range of biological contexts.

Perfiles de Polímeros Glycan la pared celular vegetal utilizando microarrays

Plant cell walls are complex matrixes of heterogeneous glycans which play an important role in the physiology and development of plants and provide the ...

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) maintain the turnover of all mature blood cell lineages. The coordination of the complex signals leading to specific HSC fates relies upon the interaction between HSCs and the intricate bone marrow microenvironment, which is still poorly understood[1-2].
We describe how by combining a newly developed specimen holder for stable animal positioning with multi-step confocal and two-photon in vivo imaging techniques, it is possible to obtain high-resolution 3D stacks containing HSPCs and their surrounding niches and to monitor them over time through multi-point time-lapse imaging. High definition imaging allows detecting ex vivo labeled hematopoietic stem and progenitor cells (HSPCs) residing within the bone marrow. Moreover, multi-point time-lapse 3D imaging, obtained with faster acquisition settings, provides accurate information about HSPC movement and the reciprocal interactions between HSPCs and stroma cells.
Tracking of HSPCs in relation to GFP positive osteoblastic cells is shown as an exemplary application of this method. This technique can be utilized to track any appropriately labeled hematopoietic or stromal cell of interest within the mouse calvarium bone marrow space.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

En Vivo Tracking 4-Dimensional de madre hematopoyéticas y células progenitoras en ratones adultos de calota de Médula Ósea

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) ...

Fecal Glucocorticoid Analysis: Non-invasive Adrenal Monitoring in Equids

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

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

Análisis de glucocorticoides fecales: Monitoreo suprarrenal no invasiva en los équidos

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

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix containing polysaccharides that include cellulose microfibrils that form both crystalline structures and cellulose chains of amorphous organization. The orientation of the cellulose fibers and their concentrations dictate the mechanical properties of the cell. Several methods are used to determine the levels of crystalline cellulose, each bringing both advantages and limitations. Some can distinguish the proportion of crystalline regions within the total cellulose. However, they are limited to whole-organ analyses that are deficient in spatiotemporal information. Others relying on live imaging, are limited by the use of imprecise dyes. Here, we report a sensitive polarized light-based system for specific quantification of relative light retardance, representing crystalline cellulose accumulation in cross sections of Arabidopsis thaliana roots. In this method, the cellular resolution and anatomical data are maintained, enabling direct comparisons between the different tissues composing the growing root. This approach opens a new analytical dimension, shedding light on the link between cell wall composition, cellular behavior and whole-organ growth.

High Resolution Quantification of Crystalline Cellulose Accumulation in Arabidopsis Roots to Monitor Tissue-specific Cell Wall Modifications

Crystalline cellulose is an important constituent of the plant cell wall. However, its quantification at a cellular resolution is technically challenging. Here, we report the use of polarized light technology and root cross sections to obtain information of cell wall composition at a spatiotemporal resolution.

Alta resolución Cuantificación de celulosa cristalina acumulación en<em&gt; Arabidopsis</em&gt; Las raíces para monitorear la célula específica de tejido de pared Modificaciones

Plant cells are surrounded by a cell wall, the composition of which determines their final size and shape. The cell wall is composed of a complex matrix ...

High-throughput CRISPR Vector Construction and Characterization of DNA Modifications by Generation of Tomato Hairy Roots

Targeted DNA mutations generated by vectors with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology have proven useful for functional genomics studies. While most cloning strategies are simple to perform, they generally use multiple steps and can require several days to generate the ultimate constructs. The method presented here is based on DNA assembly and can produce fully functional CRISPR vectors in a single cloning reaction. Vector construction can also be pooled, further increasing the efficiency and utility of the process. A modification of the method is used to create CRISPR vectors with multiple gene targets. CRISPR vectors are then transformed into tomato hairy roots to generate transgenic materials with targeted DNA modifications. Hairy roots are a useful system for testing vector functionality as they are technically simple to generate and amenable to large-scale production. The methods presented here will have wide application as they can be used to generate a variety of CRISPR vectors and be used in a wide range of plant species.

Using DNA assembly, multiple CRISPR vectors can be constructed in parallel in a single cloning reaction, making the construction of large numbers of CRISPR vectors a simple task. Tomato hairy roots are an excellent model system to validate CRISPR vectors and generate mutant materials.

De alto rendimiento CRISPR vector de la construcción y caracterización de las modificaciones del ADN mediante la generación de raíces peludas tomate

Targeted DNA mutations generated by vectors with clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology have proven useful for ...