Il lavoro nel gruppo di JWV è supportata da un Marie-Curie dell&#39;UE reintegrazione Fellowship, una sovvenzione Sysmo2 (NWO-ALW/ERASysBio), un orizzonte di finanziamento (ZonMW) e da una borsa di studio VENI (NWO-ALW). Il gruppo di OPK è supportato da diversi concede STW (NWO), un SYSMO1 (IGdeJ) e SYSMO2 sovvenzione, FSE Eurocores SynBio concedere (SynMod) e dal Centro di Genomica Kluyver di Fermentazione Industriale e l&#39;Istituto superiore per Alimenti e la Nutrizione.

<ol>
	<li>Veening, J. W., Smits, W. K., Kuipers, O. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bistability,+epigenetics,+and+bet-hedging+in+bacteria.">Bistability, epigenetics, and bet-hedging in bacteria.</a> Annu. Rev Microbiol. 62, 193-193 (2008).</li><li>Dubnau, D., Losick, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bistability+in+bacteria.">Bistability in bacteria.</a> Mol Microbiol. 61, 564-564 (2006).</li><li>Locke, J. C., Elowitz, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+movies+to+analyse+gene+circuit+dynamics+in+single+cells.">Using movies to analyse gene circuit dynamics in single cells.</a> Nat. Rev. Microbiol. 7 (5), 383-383 (2009).</li><li>Veening, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bet-hedging+and+epigenetic+inheritance+in+bacterial+cell+development.">Bet-hedging and epigenetic inheritance in bacterial cell development.</a> Proc. Natl. Acad. Sci. U. S. A. 105 (11), 4393-4393 (2008).</li><li>de Jong, I. G., Veening, J. W., Kuipers, O. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterochronic+phosphorelay+gene+expression+as+a+source+of+heterogeneity+in+Bacillus+subtilis+spore+formation.">Heterochronic phosphorelay gene expression as a source of heterogeneity in Bacillus subtilis spore formation.</a> J. Bacteriol. 192 (8), 2053-2053 (2010).</li><li>Veening, J. W., Murray, H., Errington, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+mechanism+for+cell+cycle+regulation+of+sporulation+initiation+in+Bacillus+subtilis.">A mechanism for cell cycle regulation of sporulation initiation in Bacillus subtilis.</a> Genes Dev. 23 (16), 1959-1959 (2009).</li><li>Eberhardt, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+localization+of+choline-utilization+proteins+in+Streptococcus+pneumoniae+using+novel+fluorescent+reporter+systems.">Cellular localization of choline-utilization proteins in Streptococcus pneumoniae using novel fluorescent reporter systems.</a> Mol Microbiol. 74 (2), 395-395 (2009).</li><li>Vasantha, N., Freese, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzyme+changes+during+Bacillus+subtilis+sporulation+caused+by+deprivation+of+guanine+nucleotides.">Enzyme changes during Bacillus subtilis sporulation caused by deprivation of guanine nucleotides.</a> J Bacteriol. 144 (3), 1119-1119 (1980).</li><li>Stewart, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging+and+death+in+an+organism+that+reproduces+by+morphologically+symmetric+division.">Aging and death in an organism that reproduces by morphologically symmetric division.</a> PLoS. Biol. 3, 45-45 (2005).</li><li>Rosenfeld, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+regulation+at+the+single-cell+level.">Gene regulation at the single-cell level.</a> Science. 307 (5717), 1962-1962 (2005).</li><li>Guberman, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PSICIC:+noise+and+asymmetry+in+bacterial+division+revealed+by+computational+image+analysis+at+sub-pixel+resolution.">PSICIC: noise and asymmetry in bacterial division revealed by computational image analysis at sub-pixel resolution.</a> PLoS. Comput. Biol. 4 (11), 1000233-1000233 (2008).</li><li>Montero, L. l. o. p. i. s. . P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatial+organization+of+the+flow+of+genetic+information+in+bacteria.">Spatial organization of the flow of genetic information in bacteria.</a> Nature. 466, 77-77 (2010).</li><li>Avery, O. T., Macleod, C. M., McCarty, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+chemical+nature+of+the+substance+inducing+transformation+of+pneumococcal+types:+Induction+of+transformation+by+a+desoxyribonucleic+acid+fraction+isolated+from+pneumococcus+type+III.">Studies on the chemical nature of the substance inducing transformation of pneumococcal types: Induction of transformation by a desoxyribonucleic acid fraction isolated from pneumococcus type III.</a> J Exp. Med. 79, 137-137 (1944).</li><li>Hoskins, . <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genome+of+the+bacterium+Streptococcus+pneumoniae+strain+R6.">Genome of the bacterium Streptococcus pneumoniae strain R6.</a> J Bacteriol. 183, 5709-5709 (2001).</li><li>Martin, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+recA+gene+of+Streptococcus+pneumoniae+is+part+of+a+competence-induced+operon+and+controls+lysogenic+induction.">The recA gene of Streptococcus pneumoniae is part of a competence-induced operon and controls lysogenic induction.</a> Mol Microbiol. 15, 367-367 (1995).</li></ol>

Nessun conflitto di interessi dichiarati.

A differenza di molte altre tecniche singola cellula, il time-lapse metodo di microscopia a fluorescenza qui descritto può essere usato per seguire la storia di una cella specifica in relazione ai suoi antenati, il suo comportamento, e gli eventi divisione. In combinazione con i promotori bersaglio fluorescente o proteine, specifica attivazione della via di sviluppo può essere seguito in tempo e la localizzazione delle proteine ​​e la dinamica delle proteine ​​può essere monitorato durante lo sviluppo dei batteri. Come indicato sopra, gli studi concentrandosi su diverse specie batteriche possono essere eseguite da adattare le condizioni di crescita a seconda delle esigenze di un batterio specifico. Le uniche limitazioni che abbiamo incontrato sono legati alle condizioni di crescita e la dimensione del campione. A causa di un ambiente sigillato, le condizioni di media non può essere modificato durante l&#39;esperimento. Inoltre, un massimo di quattro ceppi per esperimento può essere monitorato in modo efficiente. Considerando a pochi passi critico, l&#39;unico metodo di analisi delle cellule qui descritto può essere facilmente applicato con qualsiasi microscopio automatizzato. Di seguito, una panoramica di tali passaggi critici sarà dato. Informazioni dettagliate si possono trovare nel testo principale generali di redazione:. E &#39;consigliabile controllare le impostazioni di messa a fuoco automatica richieste per un batterio specifico prima dell&#39;esperimento. Allo stesso modo, approssimativo impostazioni ottimali per la visualizzazione della fluorescenza deve essere determinato in anticipo, se possibile. Inoltre, a seguito di un pronto time-line consente di avere tutto il materiale pronto per l&#39;uso nel tempo (pre-riscaldamento della camera di microscopio, la programmazione delle impostazioni microscopio, preparazione del vetrino uno ora prima che le cellule sono in fase di crescita desiderata, vedi figura 1) . crescita di B. subtilis in TLM e CDM: TLM e CDM sono chimicamente supporto definito la fame nel quale B. subtilis si sviluppa solo lentamente. Il periodo di tempo in cui vengono coltivate le cellule del supporto potrebbe essere prolungata a seconda del ceppo specifico. La crescita lenta impedisce alle cellule di accumulano l&#39;uno sull&#39;altro Preparazione del campione microscopio:. Bolle d&#39;aria tra la struttura del gene, il vetrino e la polizza di copertura devono essere prevenuti contro l&#39;essiccamento estensivo del agarosio-based media. Lo stesso vale per il medio / coperchio interfaccia slittamento. E &#39;fondamentale lasciare le pile a secco a sufficienza, per evitare che il nuoto e / o di crescita dello strato più Time-lapse microscopia a fluorescenza:. Pre-riscaldamento della diapositiva e la camera ambientale è fondamentale per prevenire problemi di messa a fuoco automatica più importanti. Le cellule dovrebbero essere selezionati nel bel mezzo di un tampone agar, dato che questi hanno la più alta possibilità di soggiornare in campo e mettere a fuoco durante l&#39;esperimento (a condizione che il campione è stato asciugato abbastanza bene). Un massimo di 10 posizioni per esperimenti funziona ancora correttamente. Dopo aver selezionato la prima cella di interesse solo utilizzare il software per regolare la messa a fuoco (vedi testo per i dettagli). Verificare se le cellule sono ancora a fuoco durante le prime ore della sperimentazione in intervalli di 30 min. Analisi: E &#39;importante controllare prima di procedure di analisi estese se lo sfondo del mezzo ha valori simili nei canali di fluorescenza. Piccole particelle di polvere, i componenti di media, lenti sporche o piccoli grumi agarosio può contribuire ad un aumento della fluorescenza a livello locale, rendendo il film difficili o impossibili da analizzare guasti:. Se le cellule crescono uno sopra l&#39;altro, questo potrebbe indicare che sia stato il coprioggetto attaccato troppo presto o che il mezzo non è adatto per la crescita di monostrati microcolony. Se le cellule di interesse continuamente muoiono prematuramente, mentre altre cellule sul vetrino divide felicemente, si potrebbe desiderare di controllare se si inserisce il filtro UV in posizione. Si potrebbe anche contribuire a diminuire il tempo di esposizione o l&#39;intensità della luce durante gli esperimenti a lungo.

<table border="1"><tbody><tr><th> Nome del reagente </th><th> Azienda </th><th> Numero di catalogo </th><th> Commenti (opzionale) </th></tr><tr><td> Gene Telaio </td><td> ABgene </td><td> AB-0578 </td><td> 1,7 x 2,8 centimetri </td></tr><tr><td> ad alta risoluzione a bassa fusione agarosio </td><td> Sigma </td><td> A4718 </td><td></td></tr><tr><td> fodera grande </td><td> parecchi </td><td></td><td> 24 x 50 mm </td></tr><tr><td> se lo si desidera, membrana tintura, ad esempio, FM 5-95 </td><td> Invitrogen </td><td> T23360 </td><td> coloranti membrana altri sono disponibili anche: <a href="http://probes.invitrogen.com/media/pis/mp34653.pdf">http://probes.invitrogen.com/media/pis/mp34653.pdf</a> </td></tr><tr><td> Time-lapse microscopio con camera ambientale </td><td> parecchi </td><td></td><td> vedi i dettagli per il nostro dispositivo in sezioni corrispondenti </td></tr></tbody></table>

live cell imaging of bacillus subtilis and streptococcus pneumoniae using automated time-lapse microscopy

Nel corso degli ultimi anni gli scienziati è diventato sempre più consapevole che i dati medi ottenuti da esperimenti popolazione microbica base non sono rappresentativi dello stato di comportamento, o fenotipo delle cellule singole. A causa di questa nuova visione del numero di studi singola cellula aumenta continuamente (per una rassegna recente si veda 1,2,3). Tuttavia, molte delle tecniche applicate singola cellula non consentono il monitoraggio dello sviluppo e il comportamento di una specifica cella singola nel tempo (ad esempio, citometria a flusso o microscopia standard). Qui, fornire una descrizione dettagliata di un metodo di microscopia utilizzato in diversi studi recenti 4, 5, 6, 7, che consente i seguenti e la registrazione (fluorescenza) singole cellule batteriche di Bacillus subtilis e Streptococcus pneumoniae attraverso la crescita e la divisione per molte generazioni. I film risultante può essere usato per costruire alberi filogenetici lignaggio da ripercorrere la storia di una singola cella all&#39;interno di una popolazione che ha avuto origine da un antenato comune. Questo time-lapse metodo di microscopia a fluorescenza non può essere utilizzato solo per studiare la crescita, la divisione e la differenziazione delle cellule individuali, ma anche per analizzare l&#39;effetto della storia delle cellule e ascendenza su specifici comportamento cellulare. Inoltre, microscopia time-lapse è ideale per esaminare le dinamiche di espressione genica e localizzazione di proteine ​​durante il ciclo cellulare batterica. Il metodo spiega come preparare le cellule batteriche e di costruire il vetrino da microscopio per consentire la conseguenza di singole cellule in un microcolony. In breve, le singole celle sono macchiati di un semi-solida superficie costituita da terreno di coltura integrata con agarosio su cui crescono e si dividono con un microscopio a fluorescenza all&#39;interno di una camera a temperatura controllata ambientale. Le immagini vengono acquisiti a intervalli specifici e vengono poi analizzati utilizzando il software open source ImageJ.

Watch this Scientific Journal Video about Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy at JoVE.com

Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy

Questo protocollo offre un passo-passo procedura per monitorare il comportamento singola cellula dei batteri diversi nel tempo con modalità automatizzate fluorescenza microscopia time-lapse. Inoltre, forniamo le linee guida su come analizzare le immagini di microscopia.

Cellulare Imaging in diretta di Bacillus subtilis E Streptococcus pneumoniae Utilizzando automatico Time-lapse Microscopia

During the last few years scientists became increasingly aware that average data obtained from microbial population based experiments are not ...

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JoVE Journal

Immunology and Infection

Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy

42.2K Views.  University of Groningen. Questo protocollo offre un passo-passo procedura per monitorare il comportamento singola cellula dei batteri diversi nel tempo con modalità automatizzate fluorescenza microscopia time-lapse. Inoltre, forniamo le linee guida su come analizzare le immagini di microscopia.

Video: Live Cell Imaging of Bacillus subtilis and Streptococcus pneumoniae using Automated Time-lapse Microscopy

Using Bioluminescent Imaging to Investigate Synergism Between Streptococcus pneumoniae and Influenza A Virus in Infant Mice

During the 1918 influenza virus pandemic, which killed approximately 50 million people worldwide, the majority of fatalities were not the result of infection with influenza virus alone. Instead, most individuals are thought to have succumbed to a secondary bacterial infection, predominately caused by the bacterium Streptococcus pneumoniae (the pneumococcus). The synergistic relationship between infections caused by influenza virus and the pneumococcus has subsequently been observed during the 1957 Asian influenza virus pandemic, as well as during seasonal outbreaks of the virus (reviewed in 1, 2). Here, we describe a protocol used to investigate the mechanism(s) that may be involved in increased morbidity as a result of concurrent influenza A virus and S. pneumoniae infection. We have developed an infant murine model to reliably and reproducibly demonstrate the effects of influenza virus infection of mice colonised with S. pneumoniae. Using this protocol, we have provided the first insight into the kinetics of pneumococcal transmission between co-housed, neonatal mice using in vivo imaging 3.

Using Bioluminescent Imaging to Investigate Synergism Between Streptococcus pneumoniae and Influenza A Virus in Infant Mice

A concurrent infection with influenza A virus is one of the factors implicated in the induction of invasive pneumococcal disease during asymptomatic Streptococcus pneumoniae carriage. Here we describe a mixed infection method using infant mice to investigate the synergism between these two respiratory pathogens.

Utilizzando Imaging Bioluminescent per Indagare il sinergismo tra Streptococcus pneumoniae E Influenza A virus in topi neonati

During the 1918 influenza virus pandemic, which killed approximately 50 million people worldwide, the majority of fatalities were not the result of ...

Ricerca

Immunologia e infezioni

Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry

Biofilm formation is a general attribute to almost all bacteria 1-6. When bacteria form biofilms, cells are encased in extracellular matrix that is mostly constituted by proteins and exopolysaccharides, among other factors 7-10. The microbial community encased within the biofilm often shows the differentiation of distinct subpopulation of specialized cells 11-17. These subpopulations coexist and often show spatial and temporal organization within the biofilm 18-21.
Biofilm formation in the model organism Bacillus subtilis requires the differentiation of distinct subpopulations of specialized cells. Among them, the subpopulation of matrix producers, responsible to produce and secrete the extracellular matrix of the biofilm is essential for biofilm formation 11,19. Hence, differentiation of matrix producers is a hallmark of biofilm formation in B. subtilis.
We have used fluorescent reporters to visualize and quantify the subpopulation of matrix producers in biofilms of B. subtilis 15,19,22-24. Concretely, we have observed that the subpopulation of matrix producers differentiates in response to the presence of self-produced extracellular signal surfactin 25. Interestingly, surfactin is produced by a subpopulation of specialized cells different from the subpopulation of matrix producers 15.
We have detailed in this report the technical approach necessary to visualize and quantify the subpopulation of matrix producers and surfactin producers within the biofilms of B. subtilis. To do this, fluorescent reporters of genes required for matrix production and surfactin production are inserted into the chromosome of B. subtilis. Reporters are expressed only in a subpopulation of specialized cells. Then, the subpopulations can be monitored using fluorescence microscopy and flow cytometry (See Fig 1).
The fact that different subpopulations of specialized cells coexist within multicellular communities of bacteria gives us a different perspective about the regulation of gene expression in prokaryotes. This protocol addresses this phenomenon experimentally and it can be easily adapted to any other working model, to elucidate the molecular mechanisms underlying phenotypic heterogeneity within a microbial community.

Single-cell Analysis of Bacillus subtilis Biofilms Using Fluorescence Microscopy and Flow Cytometry

Microbial biofilms are generally constituted by distinct subpopulations of specialized cells. Single-cell analysis of these subpopulations requires the use of fluorescent reporters. Here we describe a protocol to visualize and monitor several subpopulationswithin B. subtilis biofilms using fluorescence microscopy and flow cytometry.

Singola cella Analisi Bacillus subtilis I biofilm usando la microscopia a fluorescenza e citometria a flusso

Biofilm formation is a general attribute to almost all bacteria 1-6. When bacteria form biofilms, cells are encased in extracellular matrix that is mostly ...

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.

Visualizzazione delle risposte tossina batterica provocata con diretta microscopia a fluorescenza cellulare

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

Live-cell Video Microscopy of Fungal Pathogen Phagocytosis

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of phagocytes to the site where pathogens are located; (ii) recognition of pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs); (iii) engulfment of microorganisms bound to the phagocyte cell membrane, and (iv) processing of engulfed cells within maturing phagosomes and digestion of the ingested particle. Studies that assess phagocytosis in its entirety are informative1, 2, 3, 4, 5 but are limited in that they do not normally break the process down into migration, engulfment and phagosome maturation, which may be affected differentially. Furthermore, such studies assess uptake as a single event, rather than as a continuous dynamic process. We have recently developed advanced live-cell imaging technologies, and have combined these with genetic functional analysis of both pathogen and host cells to create a cross-disciplinary platform for the analysis of innate immune cell function and fungal pathogenesis. These studies have revealed novel aspects of phagocytosis that could only be observed using systematic temporal analysis of the molecular and cellular interactions between human phagocytes and fungal pathogens and infectious microorganisms more generally. For example, we have begun to define the following: (a) the components of the cell surface required for each stage of the process of recognition, engulfment and killing of fungal cells1, 6, 7, 8; (b) how surface geometry influences the efficiency of macrophage uptake and killing of yeast and hyphal cells7; and (c) how engulfment leads to alteration of the cell cycle and behavior of macrophages 9, 10.
In contrast to single time point snapshots, live-cell video microscopy enables a wide variety of host cells and pathogens to be studied as continuous sequences over lengthy time periods, providing spatial and temporal information on a broad range of dynamic processes, including cell migration, replication and vesicular trafficking. Here we describe in detail how to prepare host and fungal cells, and to conduct the video microscopy experiments. These methods can provide a user-guide for future studies with other phagocytes and microorganisms.

We describe methods for live-cell video microscopy of Candida albicans phagocytosis by macrophages. These methods enable stage-specific analysis of macrophage migration, recognition, engulfment and phagosome maturation and reveal novel aspects of phagocytosis.

Live-cellula Microscopia Video di funghi patogeni fagocitosi

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of ...

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing the mucosal surface of the nasopharynx, where it can reside, multiply and eventually overcome host defences to invade to other tissues of the host. Establishment of an infection in the normally lower respiratory tract results in pneumonia. Alternatively, the bacteria can disseminate into the bloodstream causing bacteraemia, which is associated with high mortality rates2, or else lead directly to the development of pneumococcal meningitis. Understanding the kinetics of, and immune responses to, nasopharyngeal colonization is an important aspect of S. pneumoniae infection models.
Our mouse model of intranasal colonization is adapted from human models3 and has been used by multiple research groups in the study of host-pathogen responses in the nasopharynx4-7. In the first part of the model, we use a clinical isolate of S. pneumoniae to establish a self-limiting bacterial colonization that is similar to carriage events in human adults. The procedure detailed herein involves preparation of a bacterial inoculum, followed by the establishment of a colonization event through delivery of the inoculum via an intranasal route of administration. Resident macrophages are the predominant cell type in the nasopharynx during the steady state. Typically, there are few lymphocytes present in uninfected mice8, however mucosal colonization will lead to low- to high-grade inflammation (depending on the virulence of the bacterial species and strain) that will result in an immune response and the subsequent recruitment of host immune cells. These cells can be isolated by a lavage of the tracheal contents through the nares, and correlated to the density of colonization bacteria to better understand the kinetics of the infection.

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Colonization of the murine nasopharynx with Streptococcus pneumoniae and the subsequent extraction of adherent or recruited cells is described. This technique involves flushing the nasopharynx and collection of the fluid through the nares and is adaptable for various readouts, including differential cell quantification and analysis of mRNA expression in situ.

Caratterizzazione delle risposte infiammatorie durante la colonizzazione intranasale con streptococco pneumoniae

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing ...

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact cellular functions, including energetics and signal transductions. While both fluorescent and electrophysiological methods, including electrode usage and patch-clamping, have been well developed for measuring these events in eukaryotic cells, methodology for measuring similar events in microorganisms have proven more challenging to develop given their small size in combination with the more complex outer surface of bacteria shielding the membrane. During our studies of death-initiation in Streptococcus pneumoniae (pneumococcus), we wanted to elucidate the role of membrane events, including changes in polarity, integrity, and intracellular ion concentrations. Searching the literature, we found that very few studies exist. Other investigators had monitored radioisotope uptake or equilibrium to measure ion fluxes and membrane potential and a limited number of studies, mostly in Gram-negative organisms, had seen some success using carbocyanine or oxonol fluorescent dyes to measure membrane potential, or loading bacteria with cell-permeant acetoxymethyl (AM) ester versions of ion-sensitive fluorescent indicator dyes. We therefore established and optimized protocols for measuring membrane potential, rupture, and ion-transport in the Gram-positive organism S. pneumoniae. We developed protocols using the bis-oxonol dye DiBAC4(3) and the cell-impermeant dye propidium iodide to measure membrane depolarization and rupture, respectively, as well as methods to optimally load the pneumococci with the AM esters of the ratiometric dyes Fura-2, PBFI, and BCECF to detect changes in intracellular concentrations of Ca2+, K+, and H+, respectively, using a fluorescence-detection plate reader. These protocols are the first of their kind for the pneumococcus and the majority of these dyes have not been used in any other bacterial species. Though our protocols have been optimized for S. pneumoniae, we believe these approaches should form an excellent starting-point for similar studies in other bacterial species.

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

Unlike that seen for eukaryotes, there is a paucity of studies that detail membrane depolarization and ion concentration changes in bacteria, primarily as their small size makes conventional methods of measurement difficult. Here, we detail protocols for monitoring such events in the significant Gram-positive pathogen Streptococcus pneumoniae utilizing fluorescence techniques.

Monitoraggio dei cambiamenti di polarità membrana, membrana integrità e intracellulare di ioni concentrazioni in<em&gt; Streptococcus pneumoniae</em&gt; Utilizzo di tinture fluorescenti

Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact ...

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

There are over 90 different capsular serotypes of Streptococcus pneumoniae (the pneumococcus). As well as being a tool for understanding pneumococcal epidemiology, capsular serotyping can provide useful information for vaccine efficacy and impact studies.&#160;The Quellung reaction is the gold standard method for pneumococcal capsular serotyping. The method involves testing a pneumococcal cell suspension with pooled and specific antisera directed against the capsular polysaccharide. The antigen-antibody reactions are observed microscopically. The protocol has three main steps: 1) preparation of a bacterial cell suspension, 2) mixing of cells and antisera on a glass slide, and 3) reading the Quellung reaction using a microscope. The Quellung reaction is reasonably simple to perform and can be applied wherever a suitable microscope and antisera are available.

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

The Quellung reaction is the gold standard technique for serotyping Streptococcus pneumoniae. This technique utilizes a microscope and specific pneumococcal antisera and is commonly used in reference and research laboratories worldwide.

Capsulare Sierotipizzazione di<em&gt; Streptococcus pneumoniae</em&gt; Utilizzo della reazione Quellung

There are over 90 different capsular serotypes of Streptococcus pneumoniae (the pneumococcus). As well as being a tool for understanding pneumococcal ...

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Latex agglutination reagents are widely used in microbial diagnosis, identification and serotyping. Streptococcus pneumoniae (the pneumococcus) is a major cause of morbidity and mortality world-wide. Current vaccines target the pneumococcal capsule, and there are over 90 capsular serotypes. Serotyping pneumococcal isolates is therefore important for assessing the impact of vaccination programs and for epidemiological purposes. The World Health Organization has recommended latex agglutination as an alternative method to the &#8216;gold standard&#8217; Quellung test for serotyping pneumococci. Latex agglutination is a relatively simple, quick and inexpensive method; and is therefore suitable for resource-poor settings as well as laboratories with high-volume workloads. Latex agglutination reagents can be prepared in-house utilizing commercially-sourced antibodies that are passively attached to latex particles. This manuscript describes a method of production and quality control of latex agglutination reagents, and details a sequential testing approach which is time- and cost-effective. 
This method of production and quality control may also be suitable for other testing purposes.

Capsular Serotyping of Streptococcus pneumoniae by Latex Agglutination

Latex agglutination testing is a simple, rapid and inexpensive method for serotyping Streptococcus pneumoniae, and has also been widely applied in diagnostic microbiology. This manuscript describes the in-house production of latex agglutination reagents, quality control procedures and the application of this technique to pneumococcal serotyping.

Capsulare Sierotipizzazione di<em&gt; Streptococcus pneumoniae</em&gt; Da agglutinazione al lattice

Latex agglutination reagents are widely used in microbial diagnosis, identification and serotyping. Streptococcus pneumoniae (the pneumococcus) is a major ...

Measuring Physiological Responses of Drosophila Sensory Neurons to Lipid Pheromones Using Live Calcium Imaging

Unlike mammals, insects such as Drosophila have multiple taste organs. The chemosensory neurons on the legs, proboscis, wings and ovipositor of Drosophila express gustatory receptors1,2, ion channels3-6, and ionotropic receptors7 that are involved in the detection of volatile and non-volatile sensory cues. These neurons directly contact tastants such as food, noxious substances and pheromones and therefore influence many complex behaviors such as feeding, egg-laying and mating. Electrode recordings and calcium imaging have been widely used in insects to quantify the neuronal responses evoked by these tastants. However, electrophysiology requires specialized equipment and obtaining measurements from a single taste sensillum can be technically challenging depending on the cell-type, size, and position. In addition, single neuron resolution in Drosophila can be difficult to achieve since taste sensilla house more than one type of chemosensory neuron. The live calcium imaging method described here allows responses of single gustatory neurons in live flies to be measured. This method is especially suitable for imaging neuronal responses to lipid pheromones and other ligand types that have low solubility in water-based solvents.

Measuring Physiological Responses of Drosophila Sensory Neurons to Lipid Pheromones Using Live Calcium Imaging

The forelegs and proboscis of Drosophila contain a rich repertoire of gustatory sensory neurons. Here, we present a method using calcium imaging to measure physiological responses from sensory neurons in the foreleg and proboscis of live flies upon exogenous application of a gustatory pheromone.

Misurare risposte fisiologiche di<em&gt; Drosophila</em&gt; Neuroni sensoriali a Lipid feromoni utilizza Live Calcio Imaging

Unlike mammals, insects such as Drosophila have multiple taste organs. The chemosensory neurons on the legs, proboscis, wings and ovipositor of Drosophila ...

Fluorescence Time-lapse Imaging of the Complete S. venezuelae Life Cycle Using a Microfluidic Device

Live-cell imaging of biological processes at the single cell level has been instrumental to our current understanding of the subcellular organization of bacterial cells. However, the application of time-lapse microscopy to study the cell biological processes underpinning development in the sporulating filamentous bacteria Streptomyces has been hampered by technical difficulties. 
Here we present a protocol to overcome these limitations by growing the new model species, Streptomyces venezuelae, in a commercially available microfluidic device which is connected to an inverted fluorescence widefield microscope. Unlike the classical model species, Streptomyces coelicolor, S. venezuelae sporulates in liquid, allowing the application of microfluidic growth chambers to cultivate and microscopically monitor the cellular development and differentiation of S. venezuelae over long time periods. In addition to monitoring morphological changes, the spatio-temporal distribution of fluorescently labeled target proteins can also be visualized by time-lapse microscopy. Moreover, the microfluidic platform offers the experimental flexibility to exchange the culture medium, which is used in the detailed protocol to stimulate sporulation of S. venezuelae in the microfluidic chamber. Images of the entire S. venezuelae life cycle are acquired at specific intervals and processed in the open-source software Fiji to produce movies of the recorded time-series.

Fluorescence Time-lapse Imaging of the Complete S. venezuelae Life Cycle Using a Microfluidic Device

Streptomyces are characterized by a complex life cycle that has been experimentally challenging to study by cell biological means. Here we present a protocol to perform fluorescence time-lapse microscopy of the complete life cycle by growing Streptomyces venezuelae in a microfluidic device.

Fluorescenza Time-lapse imaging del Complete<em&gt; S. venezuelae</em&gt; Ciclo di vita Uso di un dispositivo a microfluidi

Live-cell imaging of biological processes at the single cell level has been instrumental to our current understanding of the subcellular organization of ...

Cellulare Imaging in diretta di Bacillus subtilis E Streptococcus pneumoniae Utilizzando automatico Time-lapse Microscopia

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