Le travail dans le groupe de JWV est soutenu par une bourse Marie Curie de l&#39;UE de réintégration, une subvention Sysmo2 (NWO-ALW/ERASysBio), un horizon (ZonMw) de subvention et par une bourse VENI (NWO-ALW). Le groupe d&#39;OPK est soutenu par des subventions de plusieurs STW (NWO), un SYSMO1 (IGdeJ) et SYSMO2 subvention, une ESF Eurocores biologie synthétique subvention (SynMod) et par le Centre de génomique Kluyver de la fermentation industrielle et l&#39;Institut supérieur pour l&#39;alimentation et la nutrition.

<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. 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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. 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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>

Aucun conflit d&#39;intérêt déclaré.

Contrairement à beaucoup d&#39;autres techniques de cellule unique, la méthode time-lapse de microscopie par fluorescence décrites ici peuvent être utilisés pour suivre l&#39;histoire d&#39;une cellule spécifique à l&#39;égard de ses ancêtres, son comportement, et les événements de division. En combinaison avec des promoteurs cibles marquées par fluorescence ou de protéines, spécifiques activation de la voie de développement peuvent être suivies dans le temps et la localisation des protéines ainsi que la dynamique des protéines peuvent être surveillés pendant le développement bactérien. Comme indiqué plus haut, les études se concentrant sur différentes espèces bactériennes peuvent être réalisées en adaptant les conditions de croissance selon les exigences pour une bactérie spécifique. Les seules limites que nous avons rencontrées sont liées aux conditions de croissance et taille de l&#39;échantillon. En raison d&#39;un environnement hermétique, des conditions de milieu ne peut pas être changé pendant l&#39;expérience. Par ailleurs, un maximum de quatre souches par expérience peut être contrôlé efficacement. Considérant quelques critiques, la méthode seule cellule d&#39;analyse décrites ici peuvent facilement être appliqués en utilisant un microscope automatisé. Dans la suite, un aperçu de ces étapes critiques sera donnée. Des informations détaillées peuvent être trouvées dans le texte principal la préparation générale:. Il est sage de vérifier les réglages autofocus requis pour une bactérie spécifique avant l&#39;expérience. De même, environ paramètres optimaux pour la visualisation de la fluorescence devrait être déterminé à l&#39;avance, si possible. Par ailleurs, suite à un prêt de temps en ligne permet d&#39;avoir tout le matériel prêt à l&#39;emploi dans le temps (pré-réchauffement de la chambre du microscope, la programmation des réglages du microscope, la préparation de la lame, une heure avant les cellules sont en phase de croissance désiré, voir figure 1) . Croissance de B. subtilis dans le TLM et MDP: TLM et le MDP sont chimiquement défini les médias dans lesquels la famine B. subtilis ne pousse que lentement. La période de temps dans lequel les cellules sont cultivées dans les médias pourrait être prolongée en fonction de la souche spécifique. La croissance lente empêche les cellules de s&#39;accumuler sur l&#39;autre Préparation de l&#39;échantillon de microscope:. Bulles d&#39;air entre le cadre de gènes, la lame de verre et de la lamelle doit être empêché pour éviter le dessèchement vaste du milieu à base d&#39;agarose. La même chose vaut pour l&#39;interface de glissement moyen / couverture. Il est crucial de laisser les cellules assez sec, pour éviter la baignade et / ou de croissance de couches multiples Time-lapse de microscopie par fluorescence:. Pré-réchauffement de la lame ainsi que la chambre de l&#39;environnement est essentielle pour prévenir les problèmes majeurs autofocus. Les cellules doivent être choisis au milieu d&#39;un tampon d&#39;agar, puisque ceux-ci ont le plus de chance de rester dans le champ et de se concentrer pendant l&#39;expérience (fourni l&#39;échantillon a été séché assez bien). Un maximum de 10 emplacements par des expériences fonctionne toujours correctement. Après avoir sélectionné la première cellule d&#39;intérêt à utiliser le logiciel pour ajuster la mise au point (voir texte pour plus de détails). Vérifiez si les cellules sont encore en mise au point pendant les premières heures de l&#39;expérience dans des intervalles de 30 min. Analyse: Il est important de vérifier avant de procédures d&#39;analyse étendue si le contexte du milieu a les mêmes valeurs dans les canaux de fluorescence. Petites particules de poussière, les composantes moyennes, les verres sales ou minuscules touffes d&#39;agarose peuvent contribuer à la fluorescence localement accrue, ce qui rend le film difficile, voire impossible d&#39;analyser Dépannage:. Si les cellules se développent au-dessus de l&#39;autre, cela pourrait indiquer soit la lamelle a été attachée trop tôt ou que le support n&#39;est pas adapté à la croissance de monocouches microcolonie. Si les cellules d&#39;intérêt sans cesse mourir prématurément, tandis que d&#39;autres cellules sur la lame divisent heureusement, vous pouvez vérifier si vous mettez le filtre UV en position. Il pourrait également aider à diminuer le temps d&#39;exposition ou l&#39;intensité lumineuse au cours des expériences de long.

<table border="1"><tbody><tr><th> Nom du réactif </th><th> Société </th><th> Numéro de catalogue </th><th> Commentaires (optionnel) </th></tr><tr><td> Gene Cadre </td><td> ABgene </td><td> AB-0578 </td><td> 1,7 x 2,8 cm </td></tr><tr><td> haute résolution basse température de fusion d&#39;agarose </td><td> Sigma </td><td> A4718 </td><td></td></tr><tr><td> lamelle grands </td><td> plusieurs </td><td></td><td> 24 x 50 mm </td></tr><tr><td> si désiré, une membrane de teinture, par exemple FM 5-95 </td><td> Invitrogen </td><td> T23360 </td><td> colorants autre membrane sont également disponibles: <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 microscope avec chambre environnementale </td><td> plusieurs </td><td></td><td> voir les détails de notre dispositif dans les sections correspondantes </td></tr></tbody></table>

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

Durant les dernières années les scientifiques de plus en plus conscients que la moyenne des données obtenues par des expériences de la population microbienne base ne sont pas représentatifs du comportement, le statut ou le phénotype des cellules individuelles. Grâce à cette nouvelle perspective le nombre d&#39;études seule cellule augmente continuellement (pour des revues récentes, voir 1,2,3). Cependant, la plupart des techniques cellule unique appliquée ne permettent pas de suivre l&#39;évolution et le comportement d&#39;une seule cellule spécifique dans le temps (par exemple, la cytométrie en flux ou la microscopie standard). Ici, nous fournir une description détaillée d&#39;une méthode de microscopie utilisée dans plusieurs études récentes 4, 5, 6, 7, ce qui permet de suivre et d&#39;enregistrer (de fluorescence des) personne cellules bactériennes de Bacillus subtilis et Streptococcus pneumoniae par la croissance et la division pour de nombreuses générations. Les films qui en résulte peut être utilisé pour construire des arbres phylogénétiques lignée en remontant l&#39;histoire d&#39;une cellule unique dans une population qui provenaient d&#39;un ancêtre commun. Cette méthode time-lapse de fluorescence microscopie peut être utilisé non seulement pour enquêter sur la croissance, la division et la différenciation des cellules individuelles, mais aussi d&#39;analyser l&#39;effet de l&#39;histoire de la cellule et l&#39;ascendance sur le comportement cellulaire spécifique. Par ailleurs, la microscopie time-lapse est idéalement adapté à examiner la dynamique de l&#39;expression génique et la localisation des protéines au cours du cycle cellulaire de la bactérie. La méthode explique comment préparer les cellules bactériennes et de construire la lame du microscope pour permettre à l&#39;excroissance de cellules individuelles dans une microcolonie. En bref, des cellules individuelles sont repérés sur une surface semi-solide composé d&#39;un milieu de croissance complétées par d&#39;agarose sur lequel ils croissent et se divisent sous un microscope à fluorescence dans un environnement contrôlé température de la chambre. Les images sont capturées à des intervalles spécifiques et sont ensuite analysés en utilisant le logiciel 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

Ce protocole prévoit une procédure étape par étape pour surveiller le comportement seule cellule de bactéries différentes dans le temps en utilisant la fluorescence automatisée de microscopie time-lapse. En outre, nous fournir des lignes directrices comment analyser les images de microscopie.

Imagerie de cellules vivantes de la<emBacillus subtilis> Et Streptococcus pneumoniae À l&#39;aide automatisée de microscopie time-lapse

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

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Research

JoVE Journal

Immunology and Infection

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

42.0K vues.  University of Groningen. Ce protocole prévoit une procédure étape par étape pour surveiller le comportement seule cellule de bactéries différentes dans le temps en utilisant la fluorescence automatisée de microscopie time-lapse. En outre, nous fournir des lignes directrices comment analyser les images de microscopie.

Vidéo: 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.

Utiliser l&#39;imagerie Bioluminescent chargé d&#39;enquêter sur une synergie entre Streptococcus pneumoniae Et virus Influenza A de souriceaux

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

Recherche

Immunologie et infection

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.

Analyse unicellulaire des<emBacillus subtilis> Les biofilms par microscopie à fluorescence et cytométrie de flux

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 ...

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.

Caractérisation des réponses inflammatoires au cours de la colonisation intranasale avec Streptococcus pneumoniae

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

Studying Interactions of Staphylococcus aureus with Neutrophils by Flow Cytometry and Time Lapse Microscopy

We present methods to study the effect of phenol soluble modulins (PSMs) and other toxins produced and secreted by Staphylococcus aureus on neutrophils. To study the effects of the PSMs on neutrophils we isolate fresh neutrophils using density gradient centrifugation. These neutrophils are loaded with a dye that fluoresces upon calcium mobilization. The activation of neutrophils by PSMs initiates a rapid and transient increase in the free intracellular calcium concentration. In a flow cytometry experiment this rapid mobilization can be measured by monitoring the fluorescence of a pre-loaded dye that reacts to the increased concentration of free Ca2+. Using this method we can determine the PSM concentration necessary to activate the neutrophil, and measure the effects of specific and general inhibitors of the neutrophil activation.	
	To investigate the expression of the PSMs in the intracellular space, we have constructed reporter fusions of the promoter of the PSM&alpha; operon to GFP. When these reporter strains of S. aureus are phagocytosed by neutrophils, the induction of expression can be observed using fluorescence microscopy.

Studying Interactions of Staphylococcus aureus with Neutrophils by Flow Cytometry and Time Lapse Microscopy

We present methods to study the effect of PSMs and other toxins secreted by Staphylococcus aureus on neutrophils using flow cytometry and fluorescence microscopy.

L&#39;étude des interactions de<em&gt; Staphylococcus aureus</em&gt; Avec des neutrophiles par cytométrie en flux et microscopie Time Lapse

We present methods to study the effect of phenol soluble modulins (PSMs)  and other toxins produced and secreted by Staphylococcus  aureus on neutrophils. ...

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.

La surveillance des changements dans la membrane de polarité, Membrane intégrité, et intracellulaires d&#39;ions concentrations dans<em&gt; Streptococcus pneumoniae</em&gt; Utilisation des colorants fluorescents

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.

Capsulaire sérotypage des<em&gt; Streptococcus pneumoniae</em&gt; Utilisation de la réaction 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.

Capsulaire sérotypage<em&gt; Streptococcus pneumoniae</em&gt; Par agglutination au latex

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.

Mesurer les réponses physiologiques de<em&gt; Drosophila</em&gt; Neurones sensoriels à Lipid Phéromones Utilisation en direct d&#39;imagerie de calcium

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.

Fluorescence Imaging Time-lapse de la complète<em&gt; S. venezuelae</em&gt; Cycle de vie en utilisant un dispositif microfluidique

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

Prevention of Heat Stress Adverse Effects in Rats by Bacillus subtilis Strain

This study was designed to evaluate the protective effect of the Bacillus subtilis strain against complications related to heat stress. Thirty-two Sprague-Dawley rats were used in this study. Animals were orally treated twice a day for two days with B. subtilis BSB3 strain or PBS. The next day after the last treatment, each group was divided and two experimental groups (one treated with PBS and one treated with B. subtilis) were placed at 45 oC for 25 min. Two control groups stayed for 25 min at room temperature. All rats were euthanized and different parameters were analyzed in all groups. Adverse effects of heat stress are registered by the decrease of villi height and total mucosal thickness in the intestinal epithelium; translocation of bacteria from the lumen; increased vesiculation of erythrocytes and elevation of the lipopolysaccharides (LPS) level in the blood. The protective efficacy of treatment is evaluated by prevention of these side effects. The protocol was set up for the oral treatment of rats with bacteria for prevention of heat stress complications, but this protocol can be modified and used for other routes of administration and for analysis of different compounds.

Prevention of Heat Stress Adverse Effects in Rats by Bacillus subtilis Strain

We described a protocol for prevention of heat stress effects in rats by oral pre-treatment with beneficial bacteria. This protocol can be modified and used for various routes of administration and for analysis of different compounds.

Imagerie de cellules vivantes de la Et Streptococcus pneumoniae À l'aide automatisée de microscopie time-lapse