Nosso trabalho é suportado por concessões do NIH / NIGMS, NSF, USDA / Nifa e BARD para VC.

Fundo Simplástico transporte de macromoléculas através de conexões intercelulares de plantas, o plasmodesmos, é de interesse para muitos fitopatologistas e biólogos. Por exemplo, várias proteínas virais são conhecidas para regular os limites de exclusão plasmodesmal tamanho para permitir o movimento viral 1-3. Além disso, algumas proteínas endógenas, entre eles importantes reguladores do desenvolvimento, são assumidos para se deslocar de célula para célula, presumivelmente através de plasmodesmos, a função não-celular-autônoma 4. Assim, uma metodologia confiável para identificar e visualizar transporte macromolecular entre células vegetais é muito procurada. 1) Deixar crescer as plantas alvo Para a eficiência de transformação de alta, saudável, plantas robustas devem ser usados. 1. Plantas de Arabidopsis Crescer uma planta Arabidopsis na Pro-Mix BX em uma panela (10 cm x 10 cm x 10 cm) em uma câmara de ambiente controlado com fotoperíodo curto (8 horas de 130-150 μE m -2 s -1 de luz a 23 ° C/16 h escuro a 20 ° C) e 40-65% de umidade relativa de 6 a 8 semanas 5. Fertilizá-los ocasionalmente com produtos comercialmente disponíveis como descrito em 5. Folhas com o tamanho maior que 15 mm x 35 mm (a medida do comprimento inclui pecíolo) são selecionados para os experimentos. 2. N. benthamiana e N. tabacum Crescer uma planta na Pro-Mix BX em uma panela (20 cm x 20 cm x 20 cm) em uma câmara de ambiente controlado com fotoperíodo longo (16 h de 130-150 μE -2 s m -1 luz a 23 ° C / 8 hr escuro a 20 ° C) e 40-65% de umidade relativa por 7 a 10 semanas. Fertilizá-los ocasionalmente com produtos comercialmente disponíveis como descrever. Folhas com tamanho maior do que 50 mm x 70 mm para N. benthamiana, ou 100 mm x 125 mm para N. tabacum (estas medidas de comprimento não incluem pecíolo) são selecionados para os experimentos. 2) Preparação do cartucho de Gene Gun com DNA revestido de ouro Micropartículas O protocolo experimental para esta etapa já foi descrito em detalhes anteriormente 6. É muito importante usar bem DNA plasmidial purificado em altas concentrações (~ 1 mg / mL) para obter a maior eficiência de transformação para a facilidade de análise de microscopia confocal durante os últimos estágios do experimento. Para este ensaio, é importante verificar que o cartucho preparado não transforma duas ou mais células adjacentes ao mesmo tempo em alta freqüência, porque o número de células associar com um cluster de sinal fluorescente é utilizado como um indicador da extensão do transporte simplástico (ie , uma única célula que contém o sinal indica que não há movimento, enquanto um cluster sinal multicell indica movimento). A qualidade do cartucho de cada um pode ser verificado através da análise da expressão da proteína bombardeio pós 16-20 horas. Nosso protocolo 6 produz cartuchos que produzem cachos expressão multicell apenas em &lt;3% de todos os eventos de expressão neste espaço de tempo, portanto, adequado para este experimento. 3) Entrega de biobalística DNA revestido por Micropartículas <ol><li> Retire as folhas do mesmo estágio de desenvolvimento (ou seja, com o mesmo tamanho e mesma idade, consulte a etapa 1) com uma lâmina afiada e imediatamente colocá-los com os lados abaxial voltada para cima sobre uma superfície plana de isopor. O lado abaxial da folha representa um melhor substrato para bombardeio, devido à sua menor densidade de tricomas e mais fino cutícula. Folhas de Arabidopsis, por causa de seu tamanho relativamente pequeno, deve ser coberto com um pedaço de malha de tela da janela, ea malha então fixado com pinos à superfície de isopor. Manutenção de folhas planas aumenta a eficiência da entrega de partículas e minimiza os danos ao tecido durante microbombardment. </li><li> Insira o cartucho com DNA revestido por micropartículas (preparada no passo 1) para a arma. Para Arabidopsis, o tiroteio é realizada com pressões de 80-110 psi para uma mícrons micropartículas, e 140-160 psi para 0,6 mM-micropartículas. Para N. benthamiana e tabaco, o tiro é realizado sob pressões de 100-120 psi para uma mícrons micropartículas, e 160-180 psi para 0,6 mícrons micropartículas. Para Arabidopsis, que geralmente utilizam um cartucho por folha, pois cada folha tem superfície suficiente apenas para um único tiro, que se espalha micropartículas em uma área de 10-12 mm de diâmetro. N. com maior benthamiana e folhas de tabaco, bombardeios múltiplo da mesma folha são possíveis, no entanto, devem ser feitas nas posições simétricas em cada lado da nervura central para direcionar a área foliar no mesmo estágio de desenvolvimento (ver Discussão). </li><li> Retire as folhas da superfície de isopor e coloque-os inão um prato de Petri em 3 camadas de papel de filtro Whatman molhada, selar a placa de Petri com Parafilm e incube-lo em temperatura ambiente por 36-48 horas para permitir a expressão dos transgenes entregues e potencial de célula a célula-movimento de seus produtos protéicos . </li></ol> 4) Imagem de expressão da proteína O sinal fluorescente das proteínas expressas transitoriamente tag é visualizado por microscopia confocal. Cuidados devem ser tomados para encontrar as configurações de microscopia ideal para a detecção de cada proteína testada. Por exemplo, as proteínas que apresentam acúmulo intracelular limitada com intensidades de sinal fraco, como a localização plasmodesmal do Tabaco proteína movimento mosaic virus (TMV MP) 1-3,6, deve ser observado sob uma lente objetiva de 40X, o que proporciona maior resolução e sensibilidade, enquanto que as proteínas que mostram a distribuição citoplasmática com intensidades de sinal forte, como YFP livre, pode ser visualizada sob uma lente objetiva de 10X, com função de zoom de imagem confocal para uma mais rápida (ver Figura 1). Transporte simplástico é inferida a partir do aparecimento de clusters multicell que contêm o sinal fluorescente. O número desses agregados eo número de células em cada cluster é um indicativo da extensão da célula a célula-transporte. Para obter dados fiáveis, pelo menos 100 grupos de expressão devem ser registrados por cada sistema experimental. Por exemplo, se o movimento célula a célula de uma proteína é comparada em dois diferentes backgrounds genéticos (por exemplo, tipo selvagem e plantas transgênicas), de um total de 200 clusters de expressão deve ser gravado. Importante, experimentos, cujos resultados devem ser comparados uns com os outros, devem ser realizadas simultaneamente. 5. Resultados representante A figura abaixo ilustra experimentos representativos para a detecção de transporte simplástico de proteínas fluorescentes marcados. Os painéis A e B mostram as imagens típicas confocal que são obtidos microbombardment a seguir de um N. benthamiana folha com um TMV MP-YFP expressando construir. Um movimento no painel, simplástico de TMV MP-YFP é observado com base na aparência dos clusters multicell do sinal YFP. Nem todos os TMV transitoriamente expressa MP-YFP é capaz de se mover como evidenciado por uma única célula do sinal em alguns microbombardments (painel B). Estatisticamente, em &lt;40% dos clusters sinal contados, TMV MP-YFP é incapaz de se mover entre as células enquanto que em&gt; 60% dos clusters, a proteína se move entre as células 2-5, com a propagação de duas células, sendo mais frequente (ca. ~ casos 50%) (Figura 1C). As proteínas com relativamente pequeno tamanho molecular, sem a atividade do movimento inato pode difundir através PD para mover de célula para célula. Por exemplo, YFP livre, ou 1xYFP (ca. 27 kDa, painel D), se espalha entre várias células em 30% dos clusters contados (painéis C). Esta difusão não-específica não ocorre por um dimmer YFP translacional, ou 2xYFP (54 kDa, E painel), que é comparável em tamanho a TMV proteína de fusão MP-YFP (57 kDa), e que é completamente células autónomas (Figura 1C). <img src="/files/ftp_upload/2208/2208fig1.jpg" alt="Figura 1" /> Figura 1. Os resultados típicos obtidos a partir do ensaio de transporte simplástico em N. tecidos benthamiana folha. (A, B) Visualização de TMV MP-YFP. (C) A determinação quantitativa de grupos de sinal. 1xYFP e 2xYFP, livre YFP e translacional YFP dímero, respectivamente. (D) Visualização de 1xYFP. (E) Visualização de 2xYFP. Em micrografias, os painéis esquerda mostram o sinal YFP e os painéis da direita mostram imagens mesclada de YFP (em verde) e autofluorescência cloroplasto (em branco) sinais. As imagens são única seções confocal. Asteriscos no micrografias mostram que as células epidérmicas mostrando sinal YFP. Barras = 50 mm.

<ol>
	<li>Waigmann, E., Ueki, S., Trutnyeva, K., Citovsky, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ins+and+outs+of+non-destructive+cell-to-cell+and+systemic+movement+of+plant+viruses.+.">The ins and outs of non-destructive cell-to-cell and systemic movement of plant viruses. .</a> Crit Rev Plant Sci. 23, 195-250 (2004).</li><li>Lucas, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+viral+movement+proteins:+agents+for+cell-to-cell+trafficking+of+viral+genomes.">Plant viral movement proteins: agents for cell-to-cell trafficking of viral genomes.</a> Virology. 344, 169-184 (2006).</li><li>Epel, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+viruses+spread+by+diffusion+on+ER-associated+movement-protein-rafts+through+plasmodesmata+gated+by+viral+induced+host+beta-1,3-glucanases.">Plant viruses spread by diffusion on ER-associated movement-protein-rafts through plasmodesmata gated by viral induced host beta-1,3-glucanases.</a> Semin Cell Dev Biol. 20, 1074-1081 (2009).</li><li>Zambryski, P. C., Crawford, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmodesmata:+gatekeepers+for+cell-to-cell+transport+of+developmental+signals+in+plants.">Plasmodesmata: gatekeepers for cell-to-cell transport of developmental signals in plants.</a> Annu Rev Cell Dev Biol. 16, 393-421 (2000).</li><li>Rivero-Lepinckas, L., Crist, D., Scholl, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+plants+and+presercation+of+seeds.">Growth of plants and presercation of seeds.</a> Methods Mol Biol. 323, 3-12 (2006).</li><li>Ueki, S., Lacroix, B., Krichevsky, A., Lazarowitz, S. G., Citovsky, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+transient+genetic+transformation+of+Arabidopsis+leaves+by+biolistic+bombardment.">Functional transient genetic transformation of Arabidopsis leaves by biolistic bombardment.</a> Nat Protoc. 4, 71-77 (2009).</li><li>Oparka, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple,+but+not+branched,+plasmodesmata+allow+the+nonspecific+trafficking+of+proteins+in+developing+tobacco+leaves.">Simple, but not branched, plasmodesmata allow the nonspecific trafficking of proteins in developing tobacco leaves.</a> Cell. 97, 743-754 (1999).</li><li>Imlau, A., Truernit, E., Sauer, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-to-cell+and+long-distance+trafficking+of+the+green+fluorescent+protein+in+the+phloem+and+symplastic+unloading+of+the+protein+into+sink+tissues.">Cell-to-cell and long-distance trafficking of the green fluorescent protein in the phloem and symplastic unloading of the protein into sink tissues.</a> Plant Cell. 11, 309-322 (1999).</li><li>Gisel, A., Barella, S., Hempel, F. D., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+and+spatial+regulation+of+symplastic+trafficking+during+development+in+Arabidopsis+thaliana+apices.">Temporal and spatial regulation of symplastic trafficking during development in Arabidopsis thaliana apices.</a> Development. 126, 1879-1889 (1999).</li><li>Kim, I., Cho, E., Crawford, K. M., Hempel, F. D., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-to-cell+movement+of+GFP+during+embryogenesis+and+early+seedling+development+in+Arabidopsis.">Cell-to-cell movement of GFP during embryogenesis and early seedling development in Arabidopsis.</a> Proc Natl Acad Sci USA. 102, 2227-2231 (2005).</li><li>Crawford, K. M., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-targeted+and+targeted+protein+movement+through+plasmodesmata+in+leaves+in+different+developmental+and+physiological+states.">Non-targeted and targeted protein movement through plasmodesmata in leaves in different developmental and physiological states.</a> Plant Physiol. 125, 1802-1812 (2001).</li><li>Roberts, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phloem+unloading+in+sink+leaves+of+Nicotiana+benthamiana:+comparison+of+a+fluorescent+solute+with+a+fluorescent+virus.">Phloem unloading in sink leaves of Nicotiana benthamiana: comparison of a fluorescent solute with a fluorescent virus.</a> Plant Cell. 9, 1381-1396 (1997).</li><li>Guenoune-Gelbart, D., Elbaum, M., Sagi, G., Levy, A., Epel, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tobacco+mosaic+virus+(TMV)+replicase+and+movement+protein+function+synergistically+in+facilitating+TMV+spread+by+lateral+diffusion+in+the+plasmodesmal+desmotubule+of+Nicotiana+benthamiana.">Tobacco mosaic virus (TMV) replicase and movement protein function synergistically in facilitating TMV spread by lateral diffusion in the plasmodesmal desmotubule of Nicotiana benthamiana.</a> Mol Plant Microbe Interact. 21, 335-345 (2008).</li></ol>

Não há conflitos de interesse declarados.

A chave para o sucesso do ensaio de transporte simplástico é a obtenção de alta eficiência de transformação, que permite a produção de aglomerados de sinal estatisticamente significativo e facilmente detectável. Isto pode ser conseguido usando as folhas colhidas de plantas saudáveis ​​e robustas, e preparar partículas de ouro revestidas por uma preparação de DNA puro e concentrado. Usando as folhas na fase de crescimento mesmo também é vital para a confiabilidade do ensaio. Plasmodesmal abertura é conhecido por ser regulada diferencialmente, dependendo do estágio de desenvolvimento do tecido 7-11. Folhas de muitas espécies de plantas basipetally desenvolver, a partir de ápice para a base, com a parte apical da folha sendo mais maduro do que sua parte basal 12. Assim, não apenas a fase de desenvolvimento das folhas (geralmente refletida por seu tamanho e sua localização no tronco) selecionados para cada conjunto de experimentos devem ser idênticos, mas as áreas alvo de folha microbombardment devem estar localizados nas posições idênticas. Alguns estudos anteriores têm utilizado células-autônoma marcadores, como o retículo endoplasmático-tethered GFP (erGFP) 11, para distinguir as células inicialmente transformado daquelas a que a proteína testados mudou de transportes simplástico. No entanto, um estudo posterior mostrou que a expressão simultânea de algumas proteínas não-celular-autônoma com erGFP poderia induzir o seu movimento célula a célula-13, questionando a confiabilidade de erGFP como marcadores de transformação inicial e aumentando substancialmente a dificuldade na interpretação dos dados tais experimentos co-expressão. Assim, preferimos evitar a introdução de expressão de outra proteína em nosso ensaio de movimento, e, em vez disso, dependem de análise estatística dos números do conjunto do sinal.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Gold microparticles, 1.0 &mu;m in diameter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2262</td>
<td>&nbsp;</td>
<tr>
<td>Gold microparticles, 0.6 &mu;m in diameter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2263</td>
<td>&nbsp;</td>
<tr>
<td>Spermidine</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>S0266-1G</td>
<td>&nbsp;</td>
<tr>
<td>Tefzel tubing</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2441</td>
<td>&nbsp;</td>
<tr>
<td>Helios cartridge preparatory station</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2420</td>
<td>&nbsp;</td>
<tr>
<td>Tubing cutter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2422</td>
<td>&nbsp;</td>
<tr>
<td>Helios gene gun</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2432</td>
<td>&nbsp;</td>
<tr>
<td>Helium gas regulator</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2413</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

a cell-to-cell macromolecular transport assay in planta utilizing biolistic bombardment

Aqui, apresentamos um protocolo simples e rápida para detectar e avaliar a extensão da célula-célula de transporte macromolecular na planta. Neste protocolo, uma proteína fluorescente etiquetado de interesse é transitoriamente expressa no tecido vegetal após a entrega biobalística de seu DNA de codificação de construir. A distribuição intra-e intercelular da proteína com a tag é então analisada por microscopia confocal. Descrevemos esta tecnologia em detalhes, proporcionando passo-a-passo protocolos para análise e avaliar a extensão do transporte de proteínas simplástico em três espécies de plantas, Arabidopsis thaliana, Nicotiana benthamiana e N. tabacum (tabaco).

Watch this Scientific Journal Video about A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment at JoVE.com

A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

Tráfico macromolecular entre células vegetais pode ser avaliado por transitoriamente expressar uma proteína fluorescente-tag de interesse e análise de sua distribuição intra-e intercelular por microscopia confocal.

A célula-célula Assay Transporte Macromoleculares Na Planta Utilizando Bombardeio biobalística

Here, we present a simple and rapid protocol to detect and assess the extent of cell-to-cell macromolecular transport in planta. In this protocol, a ...

a-cell-to-cell-macromolecular-transport-assay-planta-utilizing

Nanyang Technological University

Research

JoVE Journal

Biology

A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

11.8K visualizações.  State University of New York at Stony Brook. Tráfico macromolecular entre células vegetais pode ser avaliado por transitoriamente expressar uma proteína fluorescente-tag de interesse e análise de sua distribuição intra-e intercelular por microscopia confocal.

Vídeo: A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

Preparation of Gene Gun Bullets and Biolistic Transfection of Neurons in Slice Culture

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed protocol for biolistic transfection of rat hippocampal slices, from the initial preparation of DNA coated bullets to the final shooting of the organotypic slice cultures using a gene gun. Gene gun transfection is an efficient and easy means of transfecting neurons and is especially useful for fluorescently labeling a small subset of cells in tissue slice. In this video, we first outline the steps required to coat gold particles with DNA. We next demonstrate how to line the inside of plastic tubing with the gold/DNA bullets, and how to cut this tubing to obtain the plastic cartridges for loading into the gene gun. Finally, we perform biolistic transfection of rat hippocampal slice cultures, demonstrating handling of the Bio-Rad Helios gene gun, and offering trouble shooting advice to obtain healthy and optimally transfected tissue slices.  

We describe a method for preparing DNA coated gold bullets and demonstrate the use of such bullets to biolistically transfect neurons in cultured hippocampal slices.

Preparação de Gene Gun Bullets e Transfection biobalística de neurônios em cultura Slice

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed ...

Biologia

Window on a Microworld: Simple Microfluidic Systems for Studying Microbial Transport in Porous Media

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in the environment, as well as directly for the transmission of pathogens to drinking water supplies. Natural porous media is composed of an intricate physical topology, varied surface chemistries, dynamic gradients of nutrients and electron acceptors, and a patchy distribution of microbes. These features vary substantially over a length scale of microns, making the results of macro-scale investigations of microbial transport difficult to interpret, and the validation of mechanistic models challenging. Here we demonstrate how simple microfluidic devices can be used to visualize microbial interactions with micro-structured habitats, to identify key processes influencing the observed phenomena, and to systematically validate predictive models. Simple, easy-to-use flow cells were constructed out of the transparent, biocompatible and oxygen-permeable material poly(dimethyl siloxane). Standard methods of photolithography were used to make micro-structured masters, and replica molding was used to cast micro-structured flow cells from the masters. The physical design of the flow cell chamber is adaptable to the experimental requirements: microchannels can vary from simple linear connections to complex topologies with feature sizes as small as 2 &mu;m. Our modular EcoChip flow cell array features dozens of identical chambers and flow control by a gravity-driven flow module. We demonstrate that through use of EcoChip devices, physical structures and pressure heads can be held constant or varied systematically while the influence of surface chemistry, fluid properties, or the characteristics of the microbial population is investigated. Through transport experiments using a non-pathogenic, green fluorescent protein-expressing Vibrio bacterial strain, we illustrate the importance of habitat structure, flow conditions, and inoculums size on fundamental transport phenomena, and with real-time particle-scale observations, demonstrate that microfluidics offer a compelling view of a hidden world.

Microfluidic devices can be used to visualize complex natural processes in real time and at the appropriate physical scales. We have developed a simple microfluidic device that mimics key features of natural porous media for studying growth and transport of bacteria in the subsurface.

Janela em um Microworld: Simple sistemas microfluídicos para estudar o transporte microbiana em Meios Porosos

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in ...

Generation of Transgenic C. elegans by Biolistic Transformation

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Generation of Transgenic C. elegans by Biolistic Transformation

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

Geração de transgênicos C. elegans Por biobalística Transformação

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid ...

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.

Agrobacterium-Mediated Virus-Induced Assay silenciamento gênico Em Cotton

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

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes

Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a crucial role in transepithelial fluid homeostasis1-3. CFTR has been implicated in two major diseases: cystic fibrosis (CF)4 and secretory diarrhea5. In CF, the synthesis or functional activity of the CFTR Cl- channel is reduced. This disorder affects approximately 1 in 2,500 Caucasians in the United States6. Excessive CFTR activity has also been implicated in cases of toxin-induced secretory diarrhea (e.g., by cholera toxin and heat stable E. coli enterotoxin) that stimulates cAMP or cGMP production in the gut7.
Accumulating evidence suggest the existence of physical and functional interactions between CFTR and a growing number of other proteins, including transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements, and these interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and also in vivo8-19. In this protocol, we focus only on the methods that aid in the study of the interactions between CFTR carboxyl terminal tail, which possesses a protein-binding motif [referred to as PSD95/Dlg1/ZO-1 (PDZ) motif], and a group of scaffold proteins, which contain a specific binding module referred to as PDZ domains. So far, several different PDZ scaffold proteins have been reported to bind to the carboxyl terminal tail of CFTR with various affinities, such as NHERF1, NHERF2, PDZK1, PDZK2, CAL (CFTR-associated ligand), Shank2, and GRASP20-27. The PDZ motif within CFTR that is recognized by PDZ scaffold proteins is the last four amino acids at the C terminus (i.e., 1477-DTRL-1480 in human CFTR)20. Interestingly, CFTR can bind more than one PDZ domain of both NHERFs and PDZK1, albeit with varying affinities22. This multivalency with respect to CFTR binding has been shown to be of functional significance, suggesting that PDZ scaffold proteins may facilitate formation of CFTR macromolecular signaling complexes for specific/selective and efficient signaling in cells16-18.
Multiple biochemical assays have been developed to study CFTR-involving protein interactions, such as co-immunoprecipitation, pull-down assay, pair-wise binding assay, colorimetric pair-wise binding assay, and macromolecular complex assembly assay16-19,28,29. Here we focus on the detailed procedures of assembling a PDZ motif-dependent CFTR-containing macromolecular complex in vitro, which is used extensively by our laboratory to study protein-protein or domain-domain interactions involving CFTR16-19,28,29.

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes

Cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel, has been reported to interact with various proteins and regulate important cellular processes; among them the CFTR PDZ motif-mediated interactions have been well documented. This protocol describes methods we developed to assemble a PDZ-dependent CFTR macromolecular signaling complex in vitro.

Análise in vitro de PDZ-dependentes Complexos Macromoleculares CFTR Sinalização

Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a ...

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media (mCeHR). Additionally, the steps for exposing and acclimatizing C. elegans grown on E. coli to axenic liquid media are described. Finally, downstream experiments that utilize axenic C. elegans illustrate the benefits of this procedure. The ability to analyze and determine C. elegans&#160;nutrient requirement was illustrated by growing N2 wild type worms in axenic liquid media with varying heme concentrations. This procedure can be replicated with other nutrients to determine the optimal concentration for worm growth and development or, to determine the toxicological effects of drug treatments. The effects of varied heme concentrations on the growth of wild type worms were determined through qualitative microscopic observation and by quantitating the number of worms that grew in each heme concentration. In addition, the effect of varied nutrient concentrations can be assayed by utilizing worms that express fluorescent sensors that respond to changes in the nutrient of interest. Furthermore, a large number of worms were easily produced for the generation of transgenic C. elegans using microparticle bombardment.

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

C. elegans is usually grown on solid agar plates or in liquid cultures seeded with E. coli. To prevent bacterial byproducts from confounding toxicological and nutritional studies, we utilized an axenic liquid medium, CeHR, to grow and synchronize a large number of worms for a range of downstream applications.

A cultura<em&gt; Caenorhabditis elegans</em &gt; Em Axenic Liquid Media e Criação de transgênicos Worms por bombardeamento com micropartículas

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media ...

Open Source High Content Analysis Utilizing Automated Fluorescence Lifetime Imaging Microscopy

We present an open source high content analysis instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions using F&#246;rster resonance energy transfer (FRET) based readouts of fixed or live cells in multiwell plates. This provides a means to screen for cell signaling processes read out using intramolecular FRET biosensors or intermolecular FRET of protein interactions such as oligomerization or heterodimerization, which can be used to identify binding partners. We describe here the functionality of this automated multiwell plate FLIM instrumentation and present exemplar data from our studies of HIV Gag protein oligomerization and a time course of a FRET biosensor in live cells. A detailed description of the practical implementation is then provided with reference to a list of hardware components and a description of the open source data acquisition software written in &#181;Manager. The application of FLIMfit, an open source MATLAB-based client for the OMERO platform, to analyze arrays of multiwell plate FLIM data is also presented. The protocols for imaging fixed and live cells are outlined and a demonstration of an automated multiwell plate FLIM experiment using cells expressing fluorescent protein-based FRET constructs is presented. This is complemented by a walk-through of the data analysis for this specific FLIM FRET data set.

We present an open source high content analysis (HCA) instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions using F&#246;rster resonance energy transfer (FRET) based readouts. Data acquisition for this openFLIM-HCA instrument is controlled by software written in &#181;Manager and data analysis is undertaken in FLIMfit.

Open Source Análise alta Conteúdo Utilizando Automated microscopia de fluorescência Lifetime Imagiologia

We present an open source high content analysis instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions ...

Methods to Study Epithelial Transport Protein Function and Expression in Native Intestine and Caco-2 Cells Grown in 3D

The intestinal epithelium has important transport and barrier functions that play key roles in normal physiological functions of the body while providing a barrier to foreign particles. Impaired epithelial transport (ion, nutrient, or drugs) has been associated with many diseases and can have consequences that extend beyond the normal physiological functions of the transporters, such as by influencing epithelial integrity and the gut microbiome. Understanding the function and regulation of transport proteins is critical for the development of improved therapeutic interventions. The biggest challenge in the study of epithelial transport is developing a suitable model system that recapitulates important features of the native intestinal epithelial cells. Several in vitro cell culture models, such as Caco-2, T-84, and HT-29-Cl.19A cells are typically used in epithelial transport research. These cell lines represent a reductionist approach to modeling the epithelium and have been used in many mechanistic studies, including their examination of epithelial-microbial interactions. However, cell monolayers do not accurately reflect cell-cell interactions and the in vivo microenvironment. Cells grown in 3D have shown to be promising models for drug permeability studies. We show that Caco-2 cells in 3D can be used to study epithelial transporters. It is also important that studies in Caco-2 cells are complemented with other models to rule out cell specific effects and to take into account the complexity of the native intestine. Several methods have been previously used to assess the functionality of transporters, such as everted sac and uptake in isolated epithelial cells or in isolated plasma membrane vesicles. Taking into consideration the challenges in the field with respect to models and the measurement of transport function, we demonstrate here a protocol to grow Caco-2 cells in 3D and describe the use of an Ussing chamber as an effective approach to measure serotonin transport, such as in intact polarized intestinal epithelia.

We describe simple methods to study the regulation of intestinal serotonin transporter (SERT) function and expression using an in vitro cell culture model of Caco-2 cells grown in 3D&#160;and an ex vivo model of mouse intestines. These methods are applicable to the study of other epithelial transporters.

Métodos de estudo epitelial Transporte função das proteínas e Expressão em Native Intestino e Caco-2 células cultivadas em 3D

The intestinal epithelium has important transport and barrier functions that play key roles in normal physiological functions of the body while providing ...

Quantifying Spatiotemporal Parameters of Cellular Exocytosis in Micropatterned Cells

Live imaging of the pHluorin tagged Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (v-SNARE) Vesicle-associated membrane protein 7 (VAMP7) by total internal reflection fluorescence microscopy (TIRFM) is a straightforward way to explore secretion from the lysosomal compartment. Taking advantage of cell culture on micropatterned surfaces to normalize cell shape, a variety of statistical tools were employed to perform a spatial analysis of secretory patterns. Using Ripley&#8217;s K function and a statistical test based on the nearest neighbor distance (NND), we confirmed that secretion from lysosomes is not a random process but shows significant clustering. Of note, our analysis revealed that exocytosis events are also clustered in nonadhesion areas, indicating that adhesion molecules are not the only structures that can induce secretory hot spots at the plasma membrane. Still, we found that cell adhesion enhances clustering. In addition to precisely defined adhesive and nonadhesive areas, the circular geometry of these micropatterns allows the use of polar coordinates, simplifying analyses. We used Kernel Density Estimation (KDE) and the cumulative distribution function on polar coordinates of exocytosis events to identify enriched areas of exocytosis. In ring-shaped micropattern cells, clustering occurred at the border between the adhesive and nonadhesive areas. Our analysis illustrates how statistical tools can be employed to investigate spatial distributions of diverse biological processes.

Live imaging of lysosomal exocytosis on micropatterned cells allows a spatial quantification of this process. Morphology normalization using micropatterns is an outstanding tool to uncover general rules about the spatial distribution of cellular processes.

Quantificando parâmetros espáteris de exocitose celular em células micropatteradas

Live imaging of the pHluorin tagged Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (v-SNARE) Vesicle-associated membrane protein 7 ...

Optimization of Crystal Growth for Neutron Macromolecular Crystallography

The use of neutron macromolecular crystallography (NMX) is expanding rapidly with most structures determined in the last decade thanks to new NMX beamlines having been built and increased availability of structure refinement software. However, the neutron sources currently available for NMX are significantly weaker than equivalent sources for X-ray crystallography. Despite advances in this field, significantly larger crystals will always be required for neutron diffraction studies, particularly with the tendency to study ever-larger macromolecules and complexes. Further improvements in methods and instrumentation suited to growing larger crystals are therefore necessary for the use of NMX to expand.
In this work, we introduce rational strategies and a crystal growth bench (OptiCrys) developed in our laboratory that combines real-time observation through a microscope-mounted video camera with precise automated control of crystallization solutions (e.g., precipitant concentration, pH, additive, temperature). We then demonstrate how this control of temperature and chemical composition facilitates the search for optimal crystallization conditions using model soluble proteins. Thorough knowledge of the crystallization phase diagram is crucial for selecting the starting position and the kinetic path for any crystallization experiment. We show how a rational approach can control the size and number of crystals generated based on knowledge of multidimensional phase diagrams.

Structural studies of biomacromolecules by crystallography require high-quality crystals. Here we demonstrate a protocol that can be used by OptiCrys (a fully automated instrument developed in our lab) and/or microdialysis buttons for growing large high-quality crystals based on knowledge of the crystallization phase diagram.