Die Autoren danken der Ellison Medical Foundation für ihre Unterstützung. Wir möchten auch die Mitglieder der Abby Dernburg Labor für die Unterstützung bei Verwendung des wormsorter danken.

1. Die Erteilung einer Synchronized Kultur Junger Erwachsener Tiere <ol><li> Würmer wachsen auf mehreren NGM-Platten mit OP50-1 E. ausgesät coli-Bakterien (aus einer gesättigten Kultur 10x konzentriert), bis viele Würmer haben die schwangeren Stadium erreicht. </li><li> Gönnen trächtige Tiere mit Ei-Prep-Lösung, um eine synchronisierte Kultur (Eier) zu erhalten. </li><li> Platte Eier auf mehrere 60-mm NGM-Platten ausgesät mit 10x konzentrierter OP50-1 mit einer Dichte von etwa 150-200 Eier / Platte. </li><li> Platten bei 25 ° C für 2 Tage (bis Würmer haben die L4 erreicht - Young Adult Stufe). </li></ol> 2. Vorbereiten Pseudomonas aeruginosa infiziert Platten und Worms <ol><li> Am Tag des Ei-Prep (Schritt 1.1) beimpfen eine PA14 :: GFP Kultur in 2 ml King-B-Medium, das Rifampicin in einer Endkonzentration von 100 ug / ml. Inkubieren der Kultur bei 37 ° C unter Rühren O / N. </li><li> Platte der PA14 :: GFP Kulturtur auf so viele Slow-Killing-Platten (SKP), die für den Test benötigt. Auf jeder SKP 150 mm Petrischale Pipette 75-100 ul gesättigten Kultur und mit einem sterilen Glasverteiler gleichmäßig verteilt. Die Inkubation bei 37 ° C für 20-24 Stunden. </li><li> Platten entfernen Inkubator und es ihnen ermöglichen, auf RT (~ 20 min) zu kühlen. Mit M9 Puffer, Wasch Würmer aus Schritt 1.4 auf PA14 :: GFP-Platten in einem minimalen Volumen der Flüssigkeit. Bei Verwendung von 150-mm-Platten, kann mehrere hundert Würmer auf einer einzigen Platte angeordnet sein. </li><li> Platten bei 25 ° C für 18-21 Stunden. Für P. aeruginosa-exponierten jungen erwachsenen Würmer, ist dies die Zeit Fenster, die optimale Verteilung der kolonisierten vs noncolonized Tiere. </li></ol> 3. Einrichten des Wormsorter Vor der Durchführung der Proben Art, sicherzustellen, dass die Maschine richtig funktioniert. Details finden Sie in http://www.unionbio.com/support/documents.aspx?id=43 erhalten werden kann, und the wesentlichen Schritte sind unten aufgeführt. <ol><li> Stellen Sie den Mantel Ventildruck auf ca. 5 psi (4,5-5,5 Bereich). </li><li> Um zu überprüfen, dass Mantel Fluiddurchsatz geeignet ist, legen Sie eine 15 ml konischen Röhrchen unter dem Spender, schalten Sie den Mantel-Ventil, und schalten Sie den Sorter-Ventil. Halten Sie das Röhrchen unter dem Spender für 60 Sekunden. Das Volumen in dem Rohr sollte 9-10 ml betragen. Wenn es außerhalb dieses Bereichs ist, passen Sie die Hülle Ventildruck. </li><li> Um sicherzustellen, dass Mantel Fluiddurchsatz (wie in Schritt 3.2 festgelegt) werden genaue Sortierung zu ermöglichen, testen Sie die Sortierrate mit 40 um Steuer Partikel: </li><li> Schalten Sie den Mantel Ventil. In etwa 25 ml der Kontrolle Partikellösung zum Stausee. </li><li> Schalten Sie den Ventilmantel und dem Probenventil. </li><li> Auf der Computer-Software, gehen Sie zum &quot;Steuerpartikel Modus&quot; und klicken Sie erwerben. </li><li> Stellen Sie sicher, dass der Partikeldurchflussrate ~ 5-8 Teilchen / sec, mit einem TOF (Time Of Flight) in etwa der Breitedes Teilchens, 40 um. Solch ein TOF bedeutet, dass nur ein einziges Objekt 40 um durchläuft in einer Zeit. Wenn die Werte außerhalb dieses Bereiches, passen Sie die Einstellungen (nach der Beschreibung oben) entsprechend. </li></ol> 4. Die Sortierung kolonisiert vs Noncolonized Worms <ol><li> Mit M9, waschen Würmer in 15 ml konischen Röhrchen. Lassen erwachsenen Würmer auf den Boden der Röhre durch die Schwerkraft sinken, und entfernen Sie den Überstand. Das Rohr wird mit frischem M9. Wiederholen Sie diesen Vorgang 3-4x. Dies entfernt einen großen Anteil der Larven sowie überschüssige Bakterien und dauert etwa 10 min. </li><li> In Würmer an die wormsorter Behälter mit einem sanft-Mischen kleiner Rührstab. </li><li> Stellen anfänglichen Signalverstärkung durch Einstellen der Grün PMT auf 600 und die rote und gelbe PMT 200. </li><li> Start der Datenerfassung, um die Einstellungen anzupassen. </li><li> Ziel für eine Art Rate von 25 bis 30 Veranstaltungen (Würmer) pro Sekunde. Wenn die Anzahl Rate zu hoch ist, verdünnte die Würmer in dem Reservoir mit M9 entsprechend. Wenn die Rate ano niedrig ist, mehr Würmer in einem kleinen Volumen M9. </li><li> Wenn das Experiment erfordert eine sehr strenge Trennung der kolonisierten vs noncolonized Würmer, stellen Sie die &quot;Koinzidenzprüfung&quot; auf &quot;reine&quot;. Dies gewährleistet, dass im Falle zweier Objekte zu nahe aneinander auftreten oder in der gleichen Tropfen, die Maschine weist die Tropfen nicht gesammelt wird. </li><li> Um die Bevölkerung von Interesse zu sortieren, ziehen Toren um die Achsen der Größe anzeigt (zu erwachsenen Würmern zu erhalten) und Fluoreszenz-Intensität (dh hoch für kolonisiert, niedrig für noncolonized). Die Werte für die Fluoreszenz Gating muss empirisch ermittelt werden. </li><li> Legen Sie ein Multi-Well-Platte oder eine Petrischale unter dem Spender, um Würmer zu sammeln öffnen Sie dann die Art Ventil Sortier Würmer zu beginnen. </li><li> Sammeln Sie eine kleine Population von Tieren, die unter dem Mikroskop, dass die Bevölkerung sortiert ist die Bevölkerung von Interesse zu überprüfen. Wenn nicht, passen Sie die Gating-Parameter und weiterhin mit Probenentnahme. </li></ol>

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Die Autoren haben nichts zu offenbaren.

Die Methode, die wir beschreiben, nutzt Fluoreszenzmarkierung von Einrichtungen außerhalb der Schnecke, um Wechselwirkungen zwischen der Schnecke und ihrer Umgebung zu folgen. In dem Fall, wir präsentieren, wurde die Trennung über die Kennzeichnung von einem Krankheitserreger und wurde zu trennen Würmer mit schweren Krankheitserreger Last von diejenigen, die keine (oder Licht) Last eingesetzt. Nachfolgende Genexpressionsanalyse fanden keinen Unterschied in der Immunantworten zwischen den beiden Gruppen nahe legt, da...

Automatische Sortierschnecke ist ähnlich wie FACS, Betriebs durch Messen eines Fluoreszenzsignals in einer Schnecke (typischerweise durch transgene Expression von Reporterproteinen zur Verfügung gestellt), wie es geht in ein Rohr gerichtet, so dass die Umleitung entweder zu einem Sammelrohr / Vertiefung oder zu einem Abfallbehälter nach um Gating Parameter durch den Forscher 1 gesetzt. Die wormsorter kann die Forschung in vielerlei Hinsicht zu erleichtern, ein Beispiel der Verwendung es als analytisches Werkzeug ist eine Studie, die räumlich-zeitliche Muster der Promotoraktivität für fast 1.000 Gene 2 gefolgt. Jedoch ist die Hauptanwendung des wormsorter in genetischen Screens, folgende Zielgenexpressionsniveaus oder Lokalisation des fluoreszierenden Proteins entlang der Achse der Schnecke 3-5. Hier beschreiben wir eine neue Anwendung für die wormsorter, in folgenden Kolonisierung der Wurm von einem fluoreszenzmarkierten Erregers. Mit diesem als ein Werkzeug, das wir auf die Beziehung zwischen pathog fokussierten Kolonisation / Last und der Immunantwort, um neue Einblicke in die Mechanismen für die Initiierung von Immunreaktionen in der Wurm verantwortlich zu gewinnen. In praktisch allen bisher untersuchten Organismen, Initiierung der angeborenen Immunantwort gegen mikrobielle Krankheitserreger, hängt von der Anerkennung pathogen-associated molecular patterns (PAMPs) und / oder Gefahr / Schaden-associated molecular patterns (gedämpft) 6,7. Die ersten konserviert sind mikrobielle Strukturen, Komponenten der mikrobiellen Zellwand, seine Flagellum oder dessen Lipid-Doppelschicht 6 umfassen, der zweite umfassen sowohl freigesetzten Moleküle (z. B. ATP 8), veränderte Proteine ​​oder andere Marker von veränderten zellulären Prozessen 9,10. Beide Arten von Signalen sind als Mustererkennungsrezeptoren (PRRS), die auf spezifische Bindung eines Moleküls aktivieren Muster eine Kette von Ereignissen, die eine schützende Antwort bezeichneten Proteinen erkannt. C elegans ist extrem nützlich als tracta gewesenble Modell, um verschiedene Aspekte der Wirt-Pathogen-Interaktionen zu sezieren, aber eine Sache, die nicht gut verstanden wird, ist, wie Immunantworten werden in der Wurm gestartet. Keiner der vermeintlichen Rezeptoren, die orthologen zu pattern recognition receptors (PRR) in anderen Organismen haben gezeigt, dass PAMPs zu binden, und viele der Orthologen von PRRS, die entscheidend für Immunreaktionen in andere Organismen sind eine überraschend begrenzten Beitrag zur Schnecken Erreger Antworten und Widerstand. Zum Beispiel wird das Drosophila Toll-Rezeptor, die für Gram-positive Pathogene Widerstand ist, in C dargestellt elegans durch eine einzige Homolog, tol-1, die Schutz gegen gramnegative Erreger Salmonella Typhimurium 11 trägt, nicht aber von anderen getesteten Gram-negative oder-positive Erreger 11,12. Diese Beobachtungen, zusammen mit Daten, die anzeigen, dass Immunantworten konnte durch Unterbrechung zellulären Proteintranslation h induziert werdenso führte einige darauf hin, dass C. elegans erkennt vor allem dämpft 9,13,14. Dennoch deuten Berichte beschreiben Fähigkeit von toten Krankheitserreger, Immunantworten zu induzieren, dass PAMP Bindung kann eine wichtige Rolle in Krankheitserreger Anerkennung in C haben werden elegans 15,16. Frühere Arbeiten mit Schwerpunkt auf Immunantworten in alters synchronisiert genetisch identisch C. elegans Populationen zeigten große individuelle Unterschiede in der Darmbesiedlung durch die bakterielle Gram-negative Krankheitserreger Pseudomonas aeruginosa. Allerdings Transkriptionsprofilierung Studien behandelt diese variabel kolonisierten Bevölkerung als eine Einheit 17,18. Unter Ausnutzung dieser Variabilität, wir ein Protokoll Fokussieren eines automatisierten wormsorter differentiell kolonisiert Populationen von Caenorhabditis elegans an GFP-exprimierenden S. ausgesetzt trennen entwickelten aeruginosa. Untersuchung der Genexpression in unterschiedlich kolonisierten Bevölkerung Facilitated Beurteilung der Beziehung zwischen Keimmenge (und der damit verbundenen Schädigung) und Immunreaktionen und lieferte neue Erkenntnisse über Pathogen Erkennung in C. elegans 19. Nachfolgend beschreiben wir das Protokoll, die angewendet könnten, um Würmer mit einem Fluoreszenz-markierten Erreger infiziert zu sortieren. Potenziellen Anwendern ist anzumerken, dass die Anzahl der Würmer erforderlich aussortiert werden müssen, hängt von der Art der nachfolgenden Analysen und Protokolle benutzt werden. Zum Beispiel im Fall von Microarray-Genexpressionsanalyse,&gt; 1.000 Würmer werden benötigt, um genügend RNA zu erhalten, wenn Standard-Protokolle verwendet werden, aber ~ 100 Würmer würde genügen, wenn Verstärkung eingesetzt wird, die eine schnelle Sammlung von Material und damit Minimierung von Stress zu die Würmer.

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

Die wormsorter ist ein Instrument analog zu einem FACS-Maschine, die in den Studien von Caenorhabditis elegans verwendet wird, in der Regel, um Würmer, basierend auf der Expression eines fluoreszierenden Reporter sortieren. Hier stellen wir eine alternative Nutzung dieses Instruments für die Sortierung Würmer nach dem Grad der Kolonisierung durch einen GFP-exprimierenden Erregers. Diese neue Nutzung gestattet uns die Beziehung zwischen Kolonisierung des Darms Schnecke und Induktion von Immunreaktionen zu adressieren. Während C. elegans Immunreaktionen auf verschiedene Erreger dokumentiert worden ist, ist es noch nicht bekannt, was sie veranlasst. Die beiden wichtigsten Möglichkeiten (die nicht gegenseitig ausschließen) sind Anerkennung der pathogen-associated molecular patterns, und den Nachweis von Schäden, die durch eine Infektion verursacht. Um zwischen den beiden Möglichkeiten zu unterscheiden, muss die Exposition gegenüber dem Erreger aus der von ihm verursachten Schäden getrennt werden. Die wormsorter aktiviert Trennung von Würmern, die durch Gram-n extensiv besiedelt wurdenegative Erreger Pseudomonas aeruginosa, mit dem Schaden wahrscheinlich durch Erreger Last verursacht, von Würmern, die in ähnlicher Weise exponiert waren, aber nicht, oder geringfügig besiedelt. Diese unterschiedliche Populationen wurden verwendet, um die Beziehung zwischen Keimmenge und der Induktion von Immunantworten Transkriptions beurteilen. Die Ergebnisse legen nahe, dass die beiden dissoziiert, unterstützt die Möglichkeit der Krankheitserreger Erkennung.

Wenn bei gleichaltrigen, genetisch identisch C. elegans sind P. ausgesetzt aeruginosa, wird eine breite Verteilung in Stufen der Kolonisation (Fig. 1A) beobachtet. Mit Hilfe des hier beschriebenen effiziente Trennung von noncolonized kolonisiert Würmer erreicht werden (Abbildung 1B) Protokoll. Im Gegensatz zu noncolonized Würmer, Würmer kolonisiert zeigen Anzeichen von Schäden, wie Trägheit und reduziert Stuhlgang 19. Letzteres kann ein Grund, ...

Watch this Scientific Journal Video about Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen at JoVE.com

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

Die wormsorter erleichtert genetische Screens in Caenorhabditis elegans durch Sortieren Würmer nach Ausdruck von fluoreszierenden Reporter. Hier beschreiben wir eine neue Nutzung: Sortierung nach einer Besiedlung durch GFP-exprimierenden Krankheitserreger, und wir beschäftigen sie, um die schlecht verstanden Rolle der Erreger Anerkennung bei der Einleitung Immunantwort zu untersuchen.

Automatische Trennung von<em&gt; C. elegans</em&gt; Variabel durch einen bakteriellen Erreger kolonisiert

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 ...

automated-separation-c-elegans-variably-colonized-bacterial

Research

JoVE Journal

Immunology and Infection

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

8.3K Aufrufe.  University of California, Berkeley.  Die wormsorter erleichtert genetische Screens in Caenorhabditis elegans durch Sortieren Würmer nach Ausdruck von fluoreszierenden Reporter. Hier beschreiben wir eine neue Nutzung: Sortierung nach einer Besiedlung durch GFP-exprimierenden Krankheitserreger, und wir beschäftigen sie, um die schlecht verstanden Rolle der Erreger Anerkennung bei der Einleitung Immunantwort zu untersuchen. 

Serie: 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.

Invasion von menschlichen Zellen durch einen bakteriellen Erreger

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

Forschung

Immunologie und Infektion

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.

Ein-Tages-Workflow-Schema für bakterielles Pathogen-Erkennung und Resistenz gegen antimikrobielle Tests aus Blutkulturen

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.

Speichel, Speicheldrüse, und Hämolymphe Abholung Ixodes scapularis Zecken

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.

Visualisierung der bakteriellen Toxin induzierten Reaktionen mit Live Cell Fluoreszenzmikroskopie

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.

Imaging InlC Sekretion to Cellular-Infektion durch den bakteriellen Erreger untersuchen<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.

Generation und Multi-phänotypischen High-Content-Screening<em&gt; Coxiella burnetii</em&gt; Transposon-Mutanten

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.

Die Entwirrung der Funktion eines bakteriellen Effektor aus einem nicht-kultivierter Pflanzenschädling eine Hefe mit Zwei-Hybrid-Screen

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.

Bereicherung der bakterielle Lipoproteine und Vorbereitung der N-terminalen Lipopeptide Strukturaufklärung durch Massenspektrometrie

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.

Ein High-Throughput, High-Content, Liquid-basierter 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 ...

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.

Automatisierte verhaltensbasierte Analyse der großen C. Elegans Populationen verwenden ein breites Sichtfeld Tracking-Plattform

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