Os autores agradecem a Fundação Médica Ellison pelo seu apoio. Gostaríamos também de agradecer aos membros do laboratório de Abby Dernburg para a assistência com o uso do wormsorter.

1. A obtenção de uma Cultura Synchronized de Jovens Adultos Animais <ol><li> Crescer vermes em várias placas NGM semeados com OP50-1 E. bactérias coli (10x concentrada a partir de uma cultura saturada) até muitos vermes atingiram a fase gravídico. </li><li> Trate os animais grávidas com solução ovo-prep para obter uma cultura sincronizado (ovos). </li><li> Ovos placa em várias placas NGM 60 mm semeado com 10x concentrado OP50-1 a uma densidade de cerca de 150-200 ovos / placa. </li><li> Incubar as placas a 25 ° C durante 2 dias (até que os vermes têm alcançado o L4 - fase de adulto jovem). </li></ol> 2. Preparando Pseudomonas aeruginosa Placas e infectando Worms <ol><li> No dia da preparação, ovo (passo 1.1) inocular uma cultura PA14 :: GFP em 2 ml de meios contendo rifampicina B de King, a uma concentração final de 100 ug / ml. Incubar a cultura a 37 ° C com agitação de O / N. </li><li> Placa da PA14 :: GFP cultura para o maior número de placas Killing Lenta (SKP), conforme necessário para o ensaio. Em cada 150 milímetros SKP Petri pipeta prato 75-100 mL de cultura saturada e espalhar uniformemente com uma espátula de vidro estéril. Incubar as placas a 37 ° C durante 20-24 horas. </li><li> Retirar as placas do incubador e permitir-se arrefecer até à temperatura ambiente (~ 20 min). Usando tampão M9, lavar vermes do passo 1.4 em PA14 :: placas GFP em um volume mínimo de líquido. Ao utilizar placas de 150 mm, centenas de vermes podem ser colocados em uma única placa. </li><li> Incubar as placas a 25 ° C durante 18-21 horas. Para P. vermes aeruginosa expostas jovens adultos, esta é a janela de tempo exibindo a distribuição ideal de colonizado vs animais não colonizados. </li></ol> 3. Configurando o Wormsorter Antes de executar a amostra tipo, verifique se a máquina está funcionando corretamente. Detalhes podem ser obtidos no http://www.unionbio.com/support/documents.aspx?id=43, e the etapas essenciais são descritas abaixo. <ol><li> Ajuste a pressão da válvula bainha para cerca de 5 psi (4,5-5,5 intervalo). </li><li> Para verificar que a taxa de fluxo de fluido bainha é apropriado, colocar um tubo de 15 ml por baixo do distribuidor, ligue a válvula de bainha e desligue a válvula de classificador. Segurar o tubo abaixo do distribuidor durante 60 seg. O volume no tubo deve ser de 9-10 ml. Se estiver fora dessa faixa, ajuste a pressão da válvula de bainha em conformidade. </li><li> Para garantir que a taxa de fluxo do fluido do invólucro (definido como no passo 3.2), vai permitir a classificação exata, testar a taxa de ordenação utilizando 40 partículas mM de controle: </li><li> Desligue a válvula de bainha. Adicionar cerca de 25 ml de solução de partículas de controlo para o reservatório. </li><li> Ligar a válvula de bainha e a válvula de amostra. </li><li> No software de computador, navegar para o &quot;modo de controle de partículas&quot; e clique em adquirir. </li><li> Certifique-se que a taxa de fluxo de partículas é de aproximadamente 5-8 partículas / s, com um TOF (tempo de vôo) aproximar a largurada partícula, de 40 ^ m. Tal TOF indica que apenas um único 40 um objecto está a passar através de cada vez. Se os valores estão fora dessa faixa, ajuste as configurações (seguindo as instruções acima) em conformidade. </li></ol> 4. Ordenando Colonizada vs não colonizados Worms <ol><li> Usando M9, lavar vermes em tubos cónicos de 15 ml. Permitir que os vermes adultos de afundar para o fundo do tubo por gravidade e remove-se o sobrenadante. Encha o tubo com fresco M9. Repita este processo 3-4x. Isto remove uma grande proporção de larvas, bem como as bactérias em excesso e demora cerca de 10 minutos. </li><li> Adicionar vermes para o reservatório wormsorter com uma barra de agitação pequena delicadamente-mistura. </li><li> Ajuste o ganho do sinal inicial, definindo o PMT Verde para 600 eo vermelho e amarelo PMT a 200. </li><li> Comece a aquisição de dados para ajustar as configurações. </li><li> Apontar para uma taxa tipo de 25-30 eventos (vermes) por segundo. Se a taxa for demasiado elevado número, diluir os vermes no reservatório com M9 conformidade. Se a taxa éo baixo, adicione mais vermes em um pequeno volume de M9. </li><li> Se o experimento requer uma separação muito rigoroso de colonizado vs vermes não colonizados, defina a &quot;verificação de coincidência&quot; a &quot;pura&quot;. Isto assegura que, no caso de dois objectos ocorrer demasiado perto um do outro ou na mesma queda, a máquina rejeita a gota em vez de a sua recolha. </li><li> Para classificar a população de interesse, desenhar portas em torno dos eixos indicando o tamanho (para obter vermes adultos) e intensidade de fluorescência (ou seja, alta de colonizado, de baixo para não colonizados). Os valores de fluorescência gating deve ser determinada empiricamente. </li><li> Colocar uma placa multi-bem ou uma placa de Petri sob o dispensador de recolher vermes em seguida, abra a válvula de tipo para começar a triagem worms. </li><li> Recolha de uma pequena população de animais para verificar ao microscópio que a população é classificada a população de interesse. Se não, ajustar os parâmetros de propagação de acordo e continuar com a coleta de amostras. </li></ol>

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Os autores não têm nada a revelar.

O método que descrevemos aproveita de marcação fluorescente de entidades fora do worm, para acompanhar as interações entre o vírus e seu ambiente. No caso que apresentamos, a separação foi baseada em rotulagem de um patógeno e foi empregado para vermes separados com carga de patógenos pesado daqueles sem (ou luz) de carga. Análise de expressão gênica Subsequente não encontraram nenhuma diferença nas respostas imunes entre os dois grupos, sugerindo que eles foram independentes da carga de patógenos. O sin...

Classificação automática verme é muito parecido com FACS, operando através da medição um sinal fluorescente em um sem-fim (normalmente fornecida pela expressão transgênica de proteínas repórter) que passa ajeitou em um tubo, o que permite o redirecionamento ou a um tubo de coleta / bem ou para um recipiente de resíduos de acordo para modular parâmetros definidos pelo pesquisador 1. O wormsorter pode facilitar a pesquisa de várias maneiras; um exemplo de empregá-la como instrumento de análise é um estudo que seguiu os padrões espaço-temporais de atividade do promotor para quase 1.000 genes 2. No entanto, o uso principal do wormsorter é nas telas genéticas, a seguir os níveis de expressão do gene alvo ou a localização da proteína fluorescente ao longo do eixo do sem-fim de 3-5. Aqui, descrevemos uma nova aplicação para o wormsorter, seguindo a colonização do worm por um patógeno fluorescente etiquetado. Com isto como uma ferramenta que incidiu sobre a relação entre Pathogen colonização / carga e da resposta imune, para ganhar novos insights sobre os mecanismos responsáveis ​​pela iniciação das respostas imunes do worm. Em praticamente todos os organismos estudados até o momento, o início da resposta imune inata a patógenos microbianos depende do reconhecimento de padrões moleculares associados a patógenos (PAMPs), e / ou padrões moleculares perigo / associado a danos (amortece) 6,7. As estruturas microbianas primeiro são conservadas que incluem componentes da parede celular microbiana, seu flagelo, ou sua bicamada lipídica 6, o segundo, incluem ambas as moléculas libertadas (por exemplo ATP 8), as proteínas modificadas ou outros marcadores de processos celulares alterados 9,10. Ambos os tipos de sinais são reconhecidos pelas proteínas designadas como receptores de reconhecimento de padrões (PRRs), que, após a ligação específica de uma molécula padrão activam uma cadeia de eventos que conduzem a uma resposta protectora. C. elegans foi extremamente útil como um Tractamodelo ble dissecar vários aspectos da interação patógeno-hospedeiro, mas uma coisa que não é bem compreendido é a forma como as respostas imunes são iniciadas no worm. Nenhum dos receptores putativos que são ortólogos de receptores de reconhecimento de padrões (SRRS) em outros organismos demonstraram ligar PAMPs, e muitos dos ortólogos de PRRs que são cruciais para as respostas imunes em outros organismos mostram surpreendentemente uma contribuição limitada para respostas verme patógeno e resistência. Por exemplo, o receptor Toll de Drosophila, que é essencial para resistir Gram positivos patogénicos, é representada em C. elegans por um único homólogo, tol-1, o que contribui para a protecção contra o agente patogénico Gram negativa Salmonella typhimurium 11, mas não a partir de outros agentes patogénicos, ou-positivas gram-negativas testadas 11,12. Estas observações, em conjunto com os dados que indicam que as respostas imunitárias poderia ser induzida por perturbar a tradução da proteína celular hcomo levou alguns a sugerir que C. elegans detecta principalmente DAMPs 9,13,14. No entanto, relatos que descrevem a capacidade de agentes patogénicos mortos para induzir respostas imunológicas sugerem que a ligação pode ser PAMP têm um papel importante no reconhecimento de patógenos em C. elegans 15,16. Trabalhos anteriores com foco em respostas imunes em sincronizado idade geneticamente idênticos C. elegans populações, demonstraram grande variabilidade individual na colonização intestinal pela Gram-negativo patógeno bacteriano Pseudomonas aeruginosa. No entanto, estudos de perfis de transcrição tratada essas populações variavelmente-colonizados como uma entidade 17,18. Aproveitando essa variabilidade, foi desenvolvido um protocolo visando ao wormsorter automatizado para separar populações colonizadas diferencialmente de Caenorhabditis elegans expostos a expressando GFP P. aeruginosa. Examinando a expressão genética em populações de forma diferente-colonizados FACIavaliação litated da relação entre a carga de patógenos (e os danos associados) e as respostas imunes e fornecidos novos insights sobre o reconhecimento do patógeno em C. elegans 19. A seguir descreve-se o protocolo, o qual podia ser aplicado para classificar vermes infectadas com qualquer agente patogénico marcado por fluorescência. Para potenciais utilizadores deve notar-se que o número de vermes necessários para ser resolvido depende da natureza das análises subsequentes e protocolos de uso. Por exemplo, no caso de análise de expressão do gene de microarray,&gt; 1000 vermes será necessária para obter o ARN suficiente, se os protocolos padrão são usadas, mas aproximadamente 100 vermes seria suficiente, se é utilizada a amplificação, permitindo rápida recolha de material e, assim, minimizar o stress aos os vermes.

<table border="0" cellpadding="0" cellspacing="0" width="927">
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		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:261px;">M9 Buffer</td>
			<td style="width:139px;">Prepared in house</td>
			<td style="width:527px;">Recipe at wormbook.org</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rifampicin&#160;</td>
			<td>Sigma</td>
			<td>R3501</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Egg prep solution&#160;</td>
			<td>Prepared in house</td>
			<td>50ml water ; 40ml bleach ; 10ml of 10N Sodium Hydroxide&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NGM plates&#160;</td>
			<td>Prepared in house</td>
			<td>Recipe at wormbook.org</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SKP plates</td>
			<td>Prepared in house</td>
			<td>Recipe same as NGM only 0.35% peptone instead of 0.25%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Control test particles&#160;</td>
			<td>Union Biometrica&#160;</td>
			<td>310-5071-001</td>
		</tr>
	</tbody>
</table>

automated separation of c. elegans variably colonized by a bacterial pathogen

O wormsorter é um instrumento semelhante a uma máquina de FACS que é utilizado em estudos de Caenorhabditis elegans, tipicamente para classificar vermes baseados na expressão de um repórter fluorescente. Aqui, destacam-se um uso alternativo deste instrumento, para classificar os vermes de acordo com seu grau de colonização por um patógeno expressando GFP. Este novo uso nos permitiu resolver a relação entre a colonização do intestino sem-fim e a indução de respostas imunitárias. Enquanto C. elegans respostas imunes a diferentes patógenos têm sido documentados, ainda é desconhecido o que os inicia. As duas possibilidades principais (que não são mutuamente exclusivos) são o reconhecimento de padrões moleculares associados a patógenos, e detecção de danos causados ​​por infecção. Para diferenciar entre as duas possibilidades, a exposição ao patógeno deve ser dissociado do dano que ela causa. A separação wormsorter habilitado de vermes que foram amplamente colonizados pela Gram-npatógeno egative Pseudomonas aeruginosa, com a provável dano causado pela carga de patógenos, de vermes que foram igualmente expostos, mas não, ou marginalmente, colonizado. Estas populações distintas foram usadas para avaliar a relação entre a carga e o agente patogénico a indução de respostas imunitárias de transcrição. Os resultados sugerem que os dois são dissociados, apoiando a possibilidade de reconhecimento do patógeno.

Quando a idade-pareado, geneticamente idênticos C. elegans estão expostos a P. aeruginosa, uma ampla distribuição é observado em níveis de colonização (Figura 1A). Com a ajuda do protocolo descrito aqui a separação eficiente de não colonizados de vermes colonizados pode ser conseguida (Figura 1B). Ao contrário dos worms não colonizados, vermes colonizados mostrar sinais de danos, tais como lentidão e reduziu a defecação 19. Este último pode ...

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Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

O wormsorter facilita telas genéticas em Caenorhabditis elegans, classificando vermes de acordo com a expressão de repórteres fluorescentes. Aqui, descrevemos um novo uso: triagem de acordo com a colonização por um patógeno expressando GFP, e empregá-lo para examinar o papel mal compreendida de reconhecimento do patógeno em iniciar respostas imunes.

A separação automática de<em&gt; C. elegans</em&gt; Variably Colonizada por um patógeno bacteriano

The wormsorter is an instrument analogous to a FACS machine that is used in studies of Caenorhabditis elegans, typically to sort worms based on expression ...

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Immunology and Infection

Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

8.3K visualizações.  University of California, Berkeley.  O wormsorter facilita telas genéticas em Caenorhabditis elegans, classificando vermes de acordo com a expressão de repórteres fluorescentes. Aqui, descrevemos um novo uso: triagem de acordo com a colonização por um patógeno expressando GFP, e empregá-lo para examinar o papel mal compreendida de reconhecimento do patógeno em iniciar respostas imunes. 

Vídeo: Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen

Invasion of Human Cells by a Bacterial Pathogen

Here we will describe how we study the invasion of human endothelial cells by bacterial pathogen Staphylococcus aureus . The general protocol can be applied to the study of cell invasion by virtually any culturable bacterium. The stages at which specific aspects of invasion can be studied, such as the role of actin rearrangement or caveolae, will be highlighted. Host cells are grown in flasks and when ready for use are seeded into 24-well plates containing Thermanox coverslips. Using coverslips allows subsequent removal of the cells from the wells to reduce interference from serum proteins deposited onto the sides of the wells (to which S. aureus would attach). Bacteria are grown to the required density and washed to remove any secreted proteins (e.g. toxins). Coverslips with confluent layers of endothelial cells are transferred to new 24-well plates containing fresh culture medium before the addition of bacteria. Bacteria and cells are then incubated together for the required amount of time in 5% CO2 at 37&deg;C. For S. aureus this is typically between 15-90 minutes. Thermanox coverslips are removed from each well and dip-washed in PBS to remove unattached bacteria. If total associated bacteria (adherent and internalised) are to be quantified, coverslips are then placed in a fresh well containing 0.5% Triton X-100 in PBS. Gentle pipetting leads to complete cell lysis and bacteria are enumerated by serial dilution and plating onto agar. If the number of bacteria that have invaded the cells is needed, coverslips are added to wells containing 500 &mu;l tissue culture medium supplemented with gentamicin and incubation continued for 1 h, which will kill all external bacteria. Coverslips can then be washed, cells lysed and bacteria enumerated by plating onto agar as described above. If the experiment requires direct visualisation, coverslips can be fixed and stained for light, fluorescence or confocal microscopy or prepared for electron microscopy.

A general protocol for the study of invasion of host cells by a bacterial pathogen, focusing on Staphylococcus aureus and human endothelial cells.

Invasão das células humanas por um agente patogénico

Here we will describe how we study the invasion of human endothelial cells by bacterial pathogen Staphylococcus aureus . The general protocol can be ...

Imunologia e Infecção

One-day Workflow Scheme for Bacterial Pathogen Detection and Antimicrobial Resistance Testing from Blood Cultures

Bloodstream infections are associated with high mortality rates because of the probable manifestation of sepsis, severe sepsis and septic shock1. Therefore, rapid administration of adequate antibiotic therapy is of foremost importance in the treatment of bloodstream infections. The critical element in this process is timing, heavily dependent on the results of bacterial identification and antibiotic susceptibility testing. Both of these parameters are routinely obtained by culture-based testing, which is time-consuming and takes on average 24-48 hours2, 4. The aim of the study was to develop DNA-based assays for rapid identification of bloodstream infections, as well as rapid antimicrobial susceptibility testing. The first assay is a eubacterial 16S rDNA-based real-time PCR assay complemented with species- or genus-specific probes5. Using these probes, Gram-negative bacteria including Pseudomonas spp., Pseudomonas aeruginosa and Escherichia coli as well as Gram-positive bacteria including Staphylococcus spp., Staphylococcus aureus, Enterococcus spp., Streptococcus spp., and Streptococcus pneumoniae could be distinguished. Using this multiprobe assay, a first identification of the causative micro-organism was given after 2 h.
Secondly, we developed a semi-molecular assay for antibiotic susceptibility testing of S. aureus, Enterococcus spp. and (facultative) aerobe Gram-negative rods6. This assay was based on a study in which PCR was used to measure the growth of bacteria7. Bacteria harvested directly from blood cultures are incubated for 6 h with a selection of antibiotics, and following a Sybr Green-based real-time PCR assay determines inhibition of growth. The combination of these two methods could direct the choice of a suitable antibiotic therapy on the same day (Figure 1). In conclusion, molecular analysis of both identification and antibiotic susceptibility offers a faster alternative for pathogen detection and could improve the diagnosis of bloodstream infections.

The design of a straightforward one-day workflow scheme for bacterial pathogen diagnostics enables the rapid recognition of bloodstream infections. The inclusion of eight clinically relevant bacterial targets and their antibiotic resistance profiles offers the clinician an initial insight on the same day, which can lead to more adequate therapy.

Um dia-Esquema de fluxo de trabalho para detecção de patógenos de bactérias e de resistência antimicrobiana de hemoculturas

Bloodstream infections are associated with high mortality rates because of the probable manifestation of sepsis, severe sepsis and septic shock1. ...

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne relapsing fever (Borrelia spp.), Rocky Mountain Spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichia chaffeensis and E. equi), anaplasmosis (Anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (Babesia spp.), Colorado tick fever (Coltivirus), and tularemia (Francisella tularensis) 1-8. To be properly transmitted into the host these infectious agents differentially regulate gene expression, interact with tick proteins, and migrate through the tick 3,9-13. For example, the Lyme disease agent, Borrelia burgdorferi, adapts through differential gene expression to the feast and famine stages of the tick's enzootic cycle 14,15. Furthermore, as an Ixodes tick consumes a bloodmeal Borrelia replicate and migrate from the midgut into the hemocoel, where they travel to the salivary glands and are transmitted into the host with the expelled saliva 9,16-19.
As a tick feeds the host typically responds with a strong hemostatic and innate immune response 11,13,20-22. Despite these host responses, I. scapularis can feed for several days because tick saliva contains proteins that are immunomodulatory, lytic agents, anticoagulants, and fibrinolysins to aid the tick feeding 3,11,20,21,23. The immunomodulatory activities possessed by tick saliva or salivary gland extract (SGE) facilitate transmission, proliferation, and dissemination of numerous tick-borne pathogens 3,20,24-27. To further understand how tick-borne infectious agents cause disease it is essential to dissect actively feeding ticks and collect tick saliva. This video protocol demonstrates dissection techniques for the collection of hemolymph and the removal of salivary glands from actively feeding I. scapularis nymphs after 48 and 72 hours post mouse placement. We also demonstrate saliva collection from an adult female I. scapularis tick.

Saliva, Salivary Gland, and Hemolymph Collection from Ixodes scapularis Ticks

The collection of infected tick hemolymph, salivary glands, and saliva is important to study how tick-borne pathogens cause disease. In this protocol we demonstrate how to collect hemolymph and salivary glands from feeding Ixodes scapularis nymphs. We also demonstrate saliva collection from female I. scapularis adults.

A saliva, glândula salivar, e Coleta de hemolinfa de carrapatos Ixodes scapularis

Ticks are found worldwide and afflict humans with many tick-borne illnesses. Ticks are vectors for pathogens that cause Lyme disease and tick-borne ...

Visualization of Bacterial Toxin Induced Responses Using Live Cell Fluorescence Microscopy

Bacterial toxins bind to cholesterol in membranes, forming pores that allow for leakage of cellular contents and influx of materials from the external environment. The cell can either recover from this insult, which requires active membrane repair processes, or else die depending on the amount of toxin exposure and cell type1. In addition, these toxins induce strong inflammatory responses in infected hosts through activation of immune cells, including macrophages, which produce an array of pro-inflammatory cytokines2. Many Gram positive bacteria produce cholesterol binding toxins which have been shown to contribute to their virulence through largely uncharacterized mechanisms.
Morphologic changes in the plasma membrane of cells exposed to these toxins include their sequestration into cholesterol-enriched surface protrusions, which can be shed into the extracellular space, suggesting an intrinsic cellular defense mechanism3,4. This process occurs on all cells in the absence of metabolic activity, and can be visualized using EM after chemical fixation4. In immune cells such as macrophages that mediate inflammation in response to toxin exposure, induced membrane vesicles are suggested to contain cytokines of the IL-1 family and may be responsible both for shedding toxin and disseminating these pro-inflammatory cytokines5,6,7. A link between IL-1&beta; release and a specific type of cell death, termed pyroptosis has been suggested, as both are caspase-1 dependent processes8. To sort out the complexities of this macrophage response, which includes toxin binding, shedding of membrane vesicles, cytokine release, and potentially cell death, we have developed labeling techniques and fluorescence microscopy methods that allow for real time visualization of toxin-cell interactions, including measurements of dysfunction and death (Figure 1). Use of live cell imaging is necessary due to limitations in other techniques. Biochemical approaches cannot resolve effects occurring in individual cells, while flow cytometry does not offer high resolution, real-time visualization of individual cells. The methods described here can be applied to kinetic analysis of responses induced by other stimuli involving complex phenotypic changes in cells.

Methods for purifying the cholesterol binding toxin streptolysin O from recombinant E. coli and visualization of toxin binding to live eukaryotic cells are described. Localized delivery of toxin induces rapid and complex changes in targeted cells revealing novel aspects of toxin biology.

Visualização das respostas toxina bacteriana induzida por microscopia de fluorescência de células vivas

Bacterial toxins bind to cholesterol in membranes, forming pores that allow for leakage of cellular contents and influx of materials from the external ...

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Bacterial intracellular pathogens can be conceived as molecular tools to dissect cellular signaling cascades due to their capacity to exquisitely manipulate and subvert cell functions which are required for the infection of host target tissues. Among these bacterial pathogens, Listeria monocytogenes is a Gram positive microorganism that has been used as a paradigm for intracellular parasitism in the characterization of cellular immune responses, and which has played instrumental roles in the discovery of molecular pathways controlling cytoskeletal and membrane trafficking dynamics. In this article, we describe a robust microscopical assay for the detection of late cellular infection stages of L. monocytogenes based on the fluorescent labeling of InlC, a secreted bacterial protein which accumulates in the cytoplasm of infected cells; this assay can be coupled to automated high-throughput small interfering RNA screens in order to characterize cellular signaling pathways involved in the up- or down-regulation of infection.

Imaging InlC Secretion to Investigate Cellular Infection by the Bacterial Pathogen Listeria monocytogenes

Listeria monocytogenes is a Gram positive bacterial pathogen frequently used as a major model for the study of intracellular parasitism. Imaging late L. monocytogenes infection stages within the context of small-interfering RNA screens allows for the global study of cellular pathways required for bacterial infection of target host cells.

Imagiologia inLC Secreção para investigar infecção celular pelo patógeno bacteriano<em&gt; Listeria monocytogenes</em

Bacterial intracellular  pathogens can be conceived as molecular tools to dissect cellular signaling  cascades due to their capacity to exquisitely ...

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence factors, which can subvert and manipulate key host functions. The study of host/pathogen interactions is therefore extremely important to understand bacterial infections and develop alternative strategies to counter infectious diseases. This approach however, requires the development of new high-throughput assays for the unbiased, automated identification and characterization of bacterial virulence determinants. Here, we describe a method for the generation of a GFP-tagged mutant library by transposon mutagenesis and the development of high-content screening approaches for the simultaneous identification of multiple transposon-associated phenotypes. Our working model is the intracellular bacterial pathogen Coxiellaburnetii, the etiological agent of the zoonosis Q fever, which is associated with severe outbreaks with a consequent health and economic burden. The obligate intracellular nature of this pathogen has, until recently, severely hampered the identification of bacterial factors involved in host pathogen interactions, making of Coxiella the ideal model for the implementation of high-throughput/high-content approaches.

Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants

Coxiella burnetii is an obligate intracellular Gram-negative bacterium responsible for the zoonotic disease Q fever. Here we describe methods for the generation of Coxiella fluorescent transposon mutants as well as the automated identification and analysis of the resulting internalization, replication and cytotoxic phenotypes.

Geração e Multi-fenotípica rastreio de alto teor de<em&gt; Coxiella burnetii</em&gt; mutantes por transposões

Invasion and colonization of host cells by bacterial pathogens depend on the activity of a large number of prokaryotic proteins, defined as virulence ...

Unravelling the Function of a Bacterial Effector from a Non-cultivable Plant Pathogen Using a Yeast Two-hybrid Screen

Unravelling the molecular mechanisms of disease manifestations is important to understand pathologies and symptom development in plant science. Bacteria have evolved different strategies to manipulate their host metabolism for their own benefit. This bacterial manipulation is often coupled with severe symptom development or the death of the affected plants. Determining the specific bacterial molecules responsible for the host manipulation has become an important field in microbiological research. After the identification of these bacterial molecules, called &#34;effectors,&#34; it is important to elucidate their function. A straightforward approach to determine the function of an effector is to identify its proteinaceous binding partner in its natural host via a yeast two-hybrid (Y2H) screen. Normally the host harbors numerous potential binding partners that cannot be predicted sufficiently by any in silico algorithm. It is thus the best choice to perform a screen with the hypothetical effector against a whole library of expressed host proteins. It is especially challenging if the causative agent is uncultivable like phytoplasma. This protocol provides step-by-step instructions for DNA purification from a phytoplasma-infected woody host plant, the amplification of the potential effector, and the subsequent identification of the plant&#39;s molecular interaction partner with a Y2H screen. Even though Y2H screens are commonly used, there is a trend to outsource this technique to biotech companies that offer the Y2H service at a cost. This protocol provides instructions on how to perform a Y2H in any decently equipped molecular biology laboratory using standard lab techniques.

Bacterial effector proteins are important for establishing successful infections. This protocol describes the experimental identification of proteinaceous binding partners of a bacterial effector protein in its natural plant host. Identifying these effector interactions via yeast two-hybrid screens has become an important tool in unravelling molecular pathogenicity strategies.

Desvendando a função de uma bacteriana Effector de um patógeno não-cultiváveis ​​meio de uma levedura Screen Two-hybrid

Unravelling the molecular mechanisms of disease manifestations is important to understand pathologies and symptom development in plant science. Bacteria ...

Enrichment of Bacterial Lipoproteins and Preparation of N-terminal Lipopeptides for Structural Determination by Mass Spectrometry

Lipoproteins are important constituents of the bacterial cell envelope and potent activators of the mammalian innate immune response. Despite their significance to both cell physiology and immunology, much remains to be discovered about novel lipoprotein forms, how they are synthesized, and the effect of the various forms on host immunity. To enable thorough studies on lipoproteins, this protocol describes a method for bacterial lipoprotein enrichment and preparation of N-terminal tryptic lipopeptides for structural determination by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Expanding on an established Triton X-114 phase partitioning method for lipoprotein extraction and enrichment from the bacterial cell membrane, the protocol includes additional steps to remove non-lipoprotein contaminants, increasing lipoprotein yield and purity. Since lipoproteins are commonly used in Toll-like receptor (TLR) assays, it is critical to first characterize the N-terminal structure by MALDI-TOF MS. Herein, a method is presented to isolate concentrated hydrophobic peptides enriched in N-terminal lipopeptides suitable for direct analysis by MALDI-TOF MS/MS. Lipoproteins that have been separated by Sodium Dodecyl Sulfate Poly-Acrylamide Gel Electrophoresis (SDS-PAGE) are transferred to a nitrocellulose membrane, digested in situ with trypsin, sequentially washed to remove polar tryptic peptides, and finally eluted with chloroform-methanol. When coupled with MS of the more polar trypsinized peptides from wash solutions, this method provides the ability to both identify the lipoprotein and characterize its N-terminus in a single experiment. Intentional sodium adduct formation can also be employed as a tool to promote more structurally informative fragmentation spectra. Ultimately, enrichment of lipoproteins and determination of their N-terminal structures will permit more extensive studies on this ubiquitous class of bacterial proteins.

The enrichment of bacterial lipoproteins using a non-ionic surfactant phase partitioning method is described for direct use in TLR assays or other applications. Further steps are detailed to prepare N-terminal tryptic lipopeptides for structural characterization by mass spectrometry.

Enriquecimento de lipoproteínas bacterianas e preparação do N-terminal Lipopeptides de determinação estrutural por espectrometria de massa

Lipoproteins are important constituents of the bacterial cell envelope and potent activators of the mammalian innate immune response. Despite their ...

A High-throughput, High-content, Liquid-based C. elegans Pathosystem

The number of new drugs identified by traditional, in vitro screens has waned, reducing the success of this approach in the search for new weapons to combat multiple drug resistance. This has led to the conclusion that researchers do not only need to find new drugs, but also need to develop new ways of finding them. Amongst the most promising candidate methods are whole-organism, in vivo assays that use high-throughput, phenotypic readouts and hosts that range from Caenorhabditis elegans to Danio rerio. These hosts have several powerful advantages, including dramatic reductions in false positive hits, as compounds that are toxic to the host and/or biounavailable are typically dropped in the initial screen, prior to costly follow up.
Here we show how our assay has been used to interrogate host variation in the well-documented C. elegans&#8212;Pseudomonas aeruginosa liquid killing pathosystem. We also demonstrate several extensions of this well-worked out technique. For example, we are able to carry out high-throughput genetic screens using RNAi in 24- or 96-well plate formats to query host factors in this host-pathogen interaction. Using this assay, whole genome screens can be completed in only a few months, which can dramatically simplify the task of identifying drug targets, potentially without the need for laborious biochemical purification approaches.
We also report here a variation of our method that substitutes the gram-positive bacterium Enterococcus faecalis for the gram-negative pathogen P. aeruginosa. Much as is the case for P. aeruginosa, killing by E. faecalis is time-dependent. Unlike previous C. elegans&#8212;E. faecalis assays, our assay for E. faecalis does not require preinfection, improving its safety profile and reducing the chances of contaminating liquid-handling equipment. The assay is highly robust, showing ~95% death rates 96 h post infection.

A High-throughput, High-content, Liquid-based C. elegans Pathosystem

Here we describe a protocol that is an adaptable, whole host, high-content screening tool that can be utilized to study host-pathogen interactions and be used for drug discovery.

Uma alta produtividade, alto teor, baseada em líquido c. elegans patossistema

The number of new drugs identified by traditional, in vitro screens has waned, reducing the success of this approach in the search for new weapons to ...

Automated Behavioral Analysis of Large C. elegans Populations Using a Wide Field-of-view Tracking Platform

Caenorhabditis elegans is a well-established animal model in biomedical research, widely employed in functional genomics and ageing studies. To assess the health and fitness of the animals under study, one typically relies on motility readouts, such as the measurement of the number of body bends or the speed of movement. These measurements usually involve manual counting, making it challenging to obtain good statistical significance, as time and labor constraints often limit the number of animals in each experiment to 25 or less. Since high statistical power is necessary to obtain reproducible results and limit false positive and negative results when weak phenotypic effects are investigated, efforts have recently been made to develop automated protocols focused on increasing the sensitivity of motility detection and multi-parametric behavioral profiling. In order to extend the limit of detection to the level needed to capture the small phenotypic changes that are often crucial in genetic studies and drug discovery, we describe here a technological development that enables the study of up to 5,000 individual animals simultaneously, increasing the statistical power of the measurements by about 1,000-fold compared to manual assays and about 100-fold compared to other available automated methods.

Automated Behavioral Analysis of Large C. elegans Populations Using a Wide Field-of-view Tracking Platform

We describe protocols for using the wide field-of-view nematode tracking platform (WF-NTP), which enables high-throughput phenotypic characterization of large populations of Caenorhabditis elegans. These protocols can be used to characterize subtle behavioral changes in mutant strains or in response to pharmacological treatment in a highly scalable fashion.

Análise comportamental de grande c. elegans populações usando um amplo campo de visão de rastreamento plataforma automatizada

Caenorhabditis elegans is a well-established animal model in biomedical research, widely employed in functional genomics and ageing studies. To assess the ...