Questo studio è stato sostenuto dal United States Department of Agriculture, Agricultural Research Service. I nomi commerciali o prodotti commerciali in questa pubblicazione sono citati unicamente allo scopo di fornire informazioni specifiche e non implica raccomandazione o approvazione da parte del Dipartimento dell&#39;Agricoltura degli Stati Uniti. USDA è un fornitore di pari opportunità e datore di lavoro.

1. La periferica Fringe di batterica Colony <ol><li> Grow X. fastidiosa (Xf) Temecula selvaggio di tipo 22, Pell delezione mutante Xf ΔpliG (utilizzando descritto in precedenza strategia di eliminazione 23), e il suo complementare XfΔpliG -C (utilizzando descritto in precedenza strategia di complementazione genetica cromosomica basata su 24) su PD2 piastre di agar 25 a 28 ° C per 5-7 giorni. </li><li> Cellophane Autoclave (1 x 1 cm 2) in acqua a 121 ° C (249 ° F) per 15 min. Pick up un pezzo di cellophane, scaricare l&#39;acqua toccando un angolo di cellophane su un piatto vuoto Petri, adagiare il cellophane oltre il 15% della superficie agar e asciugare all&#39;aria. </li><li> Pick up individuale X. colonie fastidiosa con sterile stuzzicadenti arrotondati e le cellule del punto in modo asettico su un foglio di cellophane sterilizzato sovrapposto sul 15% della superficie agar in piastre di agar. Incubare la piastras a 28 ° C per 2-3 giorni. </li><li> Esaminate la morfologia bordo delle colonie utilizzando un microscopio da dissezione con una lente obiettivo 2X e una lente oculare 10X. Fotografare la frangia periferico intorno colonie. </li></ol> 2. camere di flusso e microscopia microfluidici <ol><li> Fabbricare dispositivi microfluidici che utilizzano procedure di foto-litografico simili a quelli precedentemente descritti 5,18. Design a quattro canali paralleli con il software di progettazione assistita da computer su wafer di silicio master con i metodi litografici standard di 26. </li><li> Creare le camere di microfluidica dal maestro wafer di silicio con polidimetilsilossano (PDMS). Versare PDMS polimerizzate sopra master wafer di silicio e curare a 60 ° C per 1 ora. Staccare la replica PDMS dal master di wafer e tagliare la replica PDMS con una lama in un 22 mm x 40 mm come la stessa dimensione di un vetrino di vetro. </li><li> Esporre la replica PDMS, un vetrino di vetro (22 x 40 mm 2), ed un microscscivolo OPE (51 x 76 mm 2) per il plasma aria a 30 W per 2 min 27. Sandwich il corpo PDMS tra il vetrino di vetro e il microscopio di vetro per costruire la camera di uidic fl micro. </li><li> Praticare un foro (5,5 mm di diametro) attraverso le PDMS a ciascuna estremità del canale fantasia. Tagliare il tubo di gomma di silicone in lungo 12-20 cm. Inserire un&#39;estremità del tubo di gomma di silicone (5,1 mm di diametro esterno 2,1 mm diametro interno 0,8 mm parete) in ciascuna estremità dei canali della replica PDMS apertura e sigillare con PDMS polimerizzate a 60 ° C per 1 ora. </li><li> Collegare un&#39;altra estremità del tubo al fine spinato di connettori luer plastica. Avvolgere le camere microfluidica assemblati con il foglio di alluminio e autoclave per 20 min. </li><li> Raccogliere batteri cellule di X. fastidiosa wild type, mutante Xf ΔpliG, e complementare XfΔpliG -C tramite raschiatura, utilizzando inoculo monouso loop da PD2 piatti di media. Regolare la densità cellularead una densità ottica di 0,05 a 600 nm in PD2 brodo come descritto in precedenza 23. Raccogliere la soluzione di cellule batteriche in una tenuta di gas siringa da 1 ml. </li><li> Montare il dispositivo a microfluidi su un palco microscopio invertito. Collegare un tubo di ingresso alla siringa a tenuta di gas da 5 ml contenente PD2 brodo. Montare il 5 ml a tenuta di gas siringa con le pompe a siringa. </li><li> Collegare il tubo di scarico ad un serbatoio dei rifiuti. Mantenere una velocità media di flusso di 0,2 ml min -1 per 30 minuti per stabilizzare il sistema. </li><li> Collegare i tubi laterali di ingresso ad un 1 ml a tenuta di gas siringa contenente la soluzione cellula batterica. Lavare la soluzione cellula batterica attraverso il tubo di gomma fino a raggiungere il canale. Mantenere una portata media di 0,2 ml min -1 per altri 30 minuti, al fine di svuotare le cellule non legato dalla camera prima di cattura delle immagini. </li><li> Montare l&#39;otturatore microscopio sotto la parte di campo-adjusted del microscopio per controllare la luce. Collegare l&#39;otturatore per l&#39;otturatore coSistema ntrol e collegare il sistema di controllo dell&#39;otturatore al computer. </li><li> Montare una fotocamera digitale alla porta video del microscopio e collegarlo al computer. Eseguire il software di registrazione time-lapse, selezionare la funzione &quot;scatto&quot; dal menu, e riconoscere automaticamente l&#39;otturatore installato di default nel software per stabilire connessioni a l&#39;otturatore con il software. </li><li> Selezionare la funzione &quot;fotocamera digitale&quot; dal menu del software di registrazione time-lapse di riconoscere automaticamente la fotocamera digitale come dispositivo di acquisizione di default nel software e stabilire la comunicazione con la fotocamera digitale con il software. </li><li> Individuare le cellule batteriche in uno dei canali che utilizzano 20X ottica a contrasto di fase, quindi passare alla lente obiettivo 40X prima di cattura delle immagini. </li><li> Eseguire il software di registrazione time-lapse, selezionare la funzione &quot;acquisizione delle immagini&quot; utilizzando parametri di default dal menu per acquisire le immagini del microscopio.Quindi, aprire la funzione &quot;Acquisire time-lapse&quot; e impostare l&#39;intervallo di tempo di 30 sec 5,18,28 per la durata di 6-24 ore a seconda esperimento necessario per osservare spasmi motilità di X. fastidiosa 5,18,28. Fai clic su &quot;OK&quot; per avviare la registrazione time-lapse. Fai clic su &quot;Funzione Stack&quot; dal menù, selezionare &quot;Salva con nome&quot; per impilare le immagini nella cartella di destinazione sul computer dopo aver terminato la registrazione. </li><li> Per più canali, catturare immagini time-lapse dal primo canale ogni 30 sec per 6 ore. Spostare la lente dell&#39;obiettivo del microscopio al canale successivo per individuare le cellule bersaglio. Ripetere la funzione di time-lapse, come descritto sopra per catturare immagini in ciascuno dei quattro canali in sequenza se esperimento è configurato per utilizzare quattro canali. Continuare l&#39;acquisizione di immagini time-lapse per fino a tre giorni consecutivi. Tutti gli esperimenti sono stati condotti a temperatura ambiente (23 ± 2 ° C). </li><li> Compilare le immagini time-lapse in unfile video utilizzando il software di imaging di registrazione time-lapse. Eseguire il software di registrazione time-lapse, fai clic su &quot;funzione di Stack&quot; dal menu, e selezionare &quot;la funzione stack open&quot; per aprire i file impilati dal computer. </li><li> Avviare la funzione &quot;Crea filmato&quot; dal modulo pila, selezionando le immagini e scegliere il formato di output &quot;AVI&quot;. Fare clic su &quot;salva con nome&quot; per salvare il file video nella cartella di destinazione sul computer. </li><li> Selezionare i filmati raccolti dalla cartella di destinazione sul computer e riprodurli. Poi, osservare la motilità delle singole celle attraverso la visualizzazione risultante dell&#39;attività spasmi motilità delle cellule batteriche nei file video generati. </li></ol>

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Gli autori dichiarano di non avere interessi finanziari concorrenti.

In questo studio, abbiamo caratterizzato il comportamento movimento di X. fastidiosa Pell mutante Xf ΔpilG ei suoi complementari ceppi XfΔpilG- C a nuova concezione multipla parallelo-nano-canale micro camere di fl uidic. Le camere uidic di nuova progettazione micro fl possono avere fino a quattro camere parallele con 100 micron nano-canale in larghezza rispetto a modelli precedenti con un solo 50 micron di larghezza di canale 18. Il miglioramento più ampio nano...

Xylella fastidiosa è un batterio Gram-negativo non flagellated, patogeno che provoca una serie di malattie economicamente importanti colture, compreso il morbo di Pierce a vite (Vitis vinifera L.) 1,2, 3. Questo batterio è limitata alla xilema conducibilità dell&#39;acqua vasi. L&#39;infezione di vite provoca il blocco dei vasi xilematici e si traduce in stress idrico e carenze nutrizionali 3. Colonizzazione successo dipende dalla capacità del batterio di muoversi dal sito iniziale di infezione per il resto dell&#39;impianto 3. Contrazione motilità è un mezzo di movimento batterica flagellare-indipendente, tramite l&#39;estensione, l&#39;attaccamento, e la scomparsa della tipo polare IV pili 4 che è stato caratterizzato X. fastidiosa 5,6,7. La motilità contrazione è stato osservato da pinzette laser e microscopia a forza atomica (AFM) 8,9,10. Utilizzando queste tecniche, tmotilità delle streghe generati dal tipo IV pilus di N. gonorrhoeae e P. aeruginosa sono stati caratterizzati da fl pili etichettatura uorescently e catturare i loro movimenti al microscopio. Sebbene entrambi i metodi hanno dettagliato la forza adesiva dei singoli batteri, le procedure sono complicato e lungo 9,10. I micro camere uidic fl sono stati usati per osservare la migrazione a lunga distanza delle singole cellule, così come piccoli aggregati di cellule batteriche 5,6. Queste camere sono state progettate come un microfabbricazione-nano-canale in un piatto integrato con un sistema di registrazione di immagini time-lapse 11,12,13,14. Micro fl dispositivi da camera uidic offrono diversi vantaggi per lo studio delle interazioni comportamentali movimento e cellula-cellula di batteri: (i) fornisce una piattaforma integrata con molteplici funzionalità del canale; (Ii) le spetta esaminare i movimenti e le aggregazioni di singole cellule nelle caratteristiche nano-scala di batteri; (Iii) permette di m direttaicroscopic registrazione delle immagini delle cellule batteriche e analisi time-lapse, (iv) fornisce a lungo termine osservazioni spaziali e temporali di singoli e / o popolazioni di batteri in un micro-ambiente; (V) la portata del mezzo di coltura in un canale può essere controllata con precisione è richiesta (vi) solo un piccolo volume (1 ml) di mezzo di coltura per ciascun esperimento. Di recente, il micro fl uidic flusso sistema è stato impiegato per studiare i comportamenti di cellule batteriche in diversi microambienti 14,15,16. L&#39;adesività e l&#39;attaccamento superficie E. coli 15, X. fastidiosa 16, e Acidovorax citrulli 14 alle superfici di vetro sono stati valutati utilizzando micro fl camere uidic. La formazione di aggregazione e bio fi lm mediato dal tipo IV pili di Acidovorax citrulli sono stati analizzati 14. Inoltre, il movimento di A. citrulli osservato sotto flusso cONDIZIONI hanno dimostrato che il pili di tipo IV può svolgere un ruolo importante nella colonizzazione e la diffusione di A. citrulli in vasi xilematici sotto alburno flusso condizioni. I motilità contrazione del Pseudomonas aeruginosa e X. cellule fastidiosa sono state osservate con successo contro una corrente di fluido in una camera di flusso microfabbricazione 5,6,17. Tipo IV pilus carente pilB e pilQ mutanti di X. fastidiosa sono stati trovati di alterare profondamente la velocità di spasmi motilità nelle condizioni di fl usso in Micro Devices uidic fl 5,6,18. Gli studi condotti su adesione batterica e la motilità in micro dispositivi uidic fl indicato che i micro fl camere uidic sono particolarmente adatti per l&#39;analisi della motilità contrazioni e la migrazione dei batteri pili mediata in vitro. Questi risultati spiegano il meccanismo di migrazione spasmi-mediata che facilita l&#39;attaccamento cellula-cellula, l&#39;aggregazione e la colonizzazione all&#39;internoil padrone di casa, alla fine portano a infezioni sistemiche. Pil-Chp operone di X. fastidiosa contiene Pell, Pili, pilJ, pillola, chpB e CHPC quale segnale di trasduzione codifica Percorsi di 20. I chemocettori transmembrana legano stimoli chimici nel dominio periplasmic e attivare una cascata di segnali nella loro porzione citoplasmatica di controllare in ultima analisi batterica motilità spasmi. Nel operone Pil-Chp di X. fastidiosa, una proteina Pell fosfo-navetta è un omologo di CheY. In E. coli e P. aeruginosa, CheY è il regolatore di risposta in sistemi chemiotassi che interagiscono con le proteine ​​motrici flagelli 19, 21. Anche se i contributi di dell&#39;operone Pil-Chp verso virulenza in X. fastidiosa stati esaminati recentemente 20, il ruolo di Pell in chemiotassi operone in risposta ai segnali ambientali e regolata / motore tipo IV pili di X. fastidiosa è uncLear. Per chiarire l&#39;intuizione di regolatore di chemiotassi Pell nell&#39;attività di spasmi motilità di X. fastidiosa, una camera uidic fl micro è utilizzato per valutare la motilità contrazioni di X. fastidiosa. La Pell di X. fastidiosa è caratterizzata confrontando i fenotipi di una delezione mutante Xf ΔpliG, ceppo complementare XfΔpliG -C e la sua wild type in vitro. I risultati evidenziano il ruolo di Pell nella motilità contrazioni di X. fastidiosa.

<table><tbody><tr><td>&lt;strong&gt;Biology materials&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>&lt;em&gt;X. fastidiosa (Xf)&lt;/em&gt; Temecula wild type</td><td></td><td></td><td>Costa, H. S., &lt;em&gt;et al.&lt;/em&gt;, 2004 &lt;sup&gt;22&lt;/sup&gt;</td></tr><tr><td>&lt;em&gt;pilG&lt;/em&gt; deletion mutant &lt;em&gt;Xf&amp;Delta;pliG&lt;/em&gt;</td><td></td><td></td><td>Shi, X. Y., &lt;em&gt;et al.&lt;/em&gt;, 2007 &lt;sup&gt;26&lt;/sup&gt;</td></tr><tr><td>&lt;em&gt;pilG&lt;/em&gt; complementary strain &lt;em&gt;Xf&amp;Delta;pliG&lt;/em&gt;-C&amp;nbsp;</td><td></td><td></td><td>Davis, M. J., &lt;em&gt;et al.&lt;/em&gt; 1998 &lt;sup&gt;23&lt;/sup&gt;</td></tr><tr><td>&lt;strong&gt;Physical materials and equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Disposable inoculating loops</td><td>VWR international, Radnor, PA</td><td>#22-363-607</td><td>quantitative procedures such as bacterial collection</td></tr><tr><td>Polydimethylsiloxane (PDMS)</td><td>Dow Corning Corporation</td><td>#0002709226</td><td>Sylgard 184 silicone Elastomeric Kits</td></tr><tr><td>AmScope MD2000 digital camera</td><td>AmScope, Irvine, CA</td><td>SE305R-AZ-E</td><td>Image, video recording and measurement&amp;nbsp;</td></tr><tr><td>Tubes line</td><td>Edgewood, NY</td><td>#T4300</td><td>Connected to the syringe and microfluidic chamber</td></tr><tr><td>Plastic luer connectors</td><td>Edgewood, NY</td><td></td><td>Connected to the syringe and microfluidic chamber</td></tr><tr><td>Syringe pumps</td><td>Pico Plus, Harvard Apparatus, MA</td><td>#702209</td><td>The flow rate can be adjusted while the pump is running.</td></tr><tr><td>Syringes</td><td>Gastight, Hemilton Company, Reno, NV</td><td>#1005</td><td>Provide the flowing broth</td></tr><tr><td>Inverted Olympus IMT-2 microscope</td><td>Olympus</td><td>IMT-2 FLuoro PHase</td><td>Image observation and recording</td></tr><tr><td>SPOT-RT digital camera</td><td>Diagnostic Instruments, Inc., MI</td><td>RT230</td><td>Image, video recording and measurement</td></tr><tr><td>Microscope Shutter</td><td>The &lt;em&gt;UNIBLITZ, US&lt;/em&gt;</td><td>#LS2T2</td><td>Control camera&amp;rsquo;s exposure time</td></tr><tr><td>Microscope Shutter Control system</td><td>The &lt;em&gt;UNIBLITZ, US&lt;/em&gt;</td><td>VCM-D1</td><td>VCM-D1 Single Channel CE/UL/CSA Approved Shutter Driver</td></tr><tr><td>MetaMorph Image software</td><td>Universal Imaging Corp., PA</td><td></td><td>Real-time super-resolution image processing&amp;nbsp;</td></tr></tbody></table>

visualization of twitching motility and characterization of the role of the pilg in xylella fastidiosa

Xylella fastidiosa è un batterio non flagellated Gram-negativi che provoca una serie di malattie economicamente importanti delle piante. La motilità spasmi fornisce X. fastidiosa un mezzo per il movimento a lunga distanza intra-impianto e la colonizzazione, contribuendo verso patogenicità in X. fastidiosa. La motilità contrazioni di X. fastidiosa è gestito da pili di tipo IV. Tipo IV pili di Xylella fastidiosa sono regolati da Pell, un regolatore di chemiotassi in Pil-CHP proteine ​​di codifica operone che sono coinvolti con le vie di trasduzione del segnale. Per chiarire i ruoli di Pell nella motilità contrazioni di X. fastidiosa, un Pell -carente mutante Xf ΔpilG e il suo sforzo complementare XfΔpilG- C contenente nativo Pell sono stati sviluppati. A camere di microfluidica integrati con un sistema di registrazione di immagini time-lapse è stato utilizzato per osservare spasmi motilità in XfΔpIlg, XfΔpilG- C e il suo ceppo wild-type. Usando questo sistema di registrazione, permette a lungo termine osservazioni spaziali e temporali di aggregazione, la migrazione delle singole cellule e delle popolazioni di batteri via spasmi motilità. X. fastidiosa wild type e complementare ceppo XfΔpilG- C hanno mostrato caratteristiche tipiche spasmi motilità osservati direttamente nelle camere di flusso microfluidica, mentre mutante XfΔpliG esposto il fenotipo carente spasmi. Questo studio dimostra che pilg contribuisce alla motilità spasmi di X. fastidiosa. La camera di flusso microfluidica viene utilizzato come mezzo per osservare spasmi motilità.

La presenza di una frangia colonia periferico indicativa di tipo IV pilus-mediata spasmi motilità, è stato osservato nelle colonie di X. fastidiosa wild type e complementare ceppo Xf ΔpliG -C (Figura 1). Mutante XfΔpliG, tuttavia, non ha evidenziato una frangia intorno alla periferia delle colonie (Figura 1). Time-lapse imaging di cellule batteriche in camere a flusso nano-microfluidica ha rivelato che spasmi motil...

Watch this Scientific Journal Video about Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa at JoVE.com

Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa

In questo studio, una camera di flusso nano-microfluidica è stato impiegato per visualizzare e caratterizzare funzionalmente la motilità contrazione del Xylella fastidiosa, un batterio che causa la malattia di Pierce a Grapevine.

Visualizzazione di Spasmi motilità e caratterizzazione del ruolo del<em&gt; Pell</em&gt; in<em&gt; Fastidiosa Xylella</em

Xylella fastidiosa is a Gram-negative non-flagellated bacterium that causes a number of economically important diseases of plants. The twitching motility ...

visualization-twitching-motility-characterization-role-pilg-xylella

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa

10.7K Views.  University of California, Davis.  In questo studio, una camera di flusso nano-microfluidica è stato impiegato per visualizzare e caratterizzare funzionalmente la motilità contrazione del Xylella fastidiosa, un batterio che causa la malattia di Pierce a Grapevine. 

Video: Visualization of Twitching Motility and Characterization of the Role of the PilG in Xylella fastidiosa

Fluorescence Live-cell Imaging of the Complete Vegetative Cell Cycle of the Slow-growing Social Bacterium Myxococcus xanthus

Fluorescence live-cell imaging of bacterial cells is a key method in the analysis of the spatial and temporal dynamics of proteins and chromosomes underlying central cell cycle events. However, imaging of these molecules in slow-growing bacteria represents a challenge due to photobleaching of fluorophores and phototoxicity during image acquisition. Here, we describe a simple protocol to circumvent these limitations in the case of Myxococcus xanthus (which has a generation time of 4 - 6 h). To this end, M. xanthus cells are grown on a thick nutrient-containing agar pad in a temperature-controlled humid environment. Under these conditions, we determine the doubling time of individual cells by following the growth of single cells. Moreover, key cellular processes such as chromosome segregation and cell division can be imaged by fluorescence live-cell imaging of cells containing relevant fluorescently labeled marker proteins such as ParB-YFP, FtsZ-GFP, and mCherry-PomX over multiple cell cycles. Subsequently, the acquired images are processed to generate montages and/or movies.

Fluorescence Live-cell Imaging of the Complete Vegetative Cell Cycle of the Slow-growing Social Bacterium Myxococcus xanthus

Bacterial cells are spatially highly organized. To follow this organization over time in slow growing Myxococcus xanthus cells, a set-up for fluorescence live-cell imaging with high spatiotemporal resolution over several generations was developed. Using this method, spatiotemporal dynamics of important proteins for chromosome segregation and cell division could be determined.

Imaging di fluorescenza Live-cella del completo ciclo cellulare vegetativo della lenta crescita sociale batterio xanthus di Myxococcus

Fluorescence live-cell imaging of bacterial cells is a key method in the analysis of the spatial and temporal dynamics of proteins and chromosomes ...

Ricerca

Biochimica

Establishment of Larval Zebrafish as an Animal Model to Investigate Trypanosoma cruzi Motility In Vivo

Chagas disease is a parasitic infection caused by Trypanosoma cruzi, whose motility is not only important for localization, but also for cellular binding and invasion. Current animal models for the study of T. cruzi allow limited observation of parasites in vivo, representing a challenge for understanding parasite behavior during the initial stages of infection in humans. This protozoan has a flagellar stage in both vector and mammalian hosts, but there are no studies describing its motility in vivo.The objective of this project was to establish a live vertebrate zebrafish model to evaluate T. cruzi motility in the vascular system. Transparent zebrafish larvae were injected with fluorescently labeled trypomastigotes and observed using light sheet fluorescence microscopy (LSFM), a noninvasive method to visualize live organisms with high optical resolution. The parasites could be visualized for extended periods of time due to this technique&#39;s relatively low risk of photodamage compared to confocal or epifluorescence microscopy. T. cruzi parasites were observed traveling in the circulatory system of live zebrafish in different-sized blood vessels and the yolk. They could also be seen attached to the yolk sac wall and to the atrioventricular valve despite the strong forces associated with heart contractions. LSFM of T. cruzi-inoculated zebrafish larvae is a valuable method that can be used to visualize circulating parasites and evaluate their tropism, migration patterns, and motility in the dynamic environment of the cardiovascular system of a live animal.

Establishment of Larval Zebrafish as an Animal Model to Investigate Trypanosoma cruzi Motility In Vivo

In this protocol, fluorescently labeled T. cruzi&#160;were injected into transparent zebrafish larvae, and parasite motility was observed in vivo using light sheet fluorescence microscopy.

Stabilimento di larvale Zebrafish come modello animale per indagare Trypanosoma cruzi motilità In Vivo

Chagas disease is a parasitic infection caused by Trypanosoma cruzi, whose motility is not only important for localization, but also for cellular binding ...

Biologia dello sviluppo

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 e Multi-fenotipica Screening-Alto contenuto di<em&gt; Coxiella burnetii</em&gt; Mutants transposon

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

Immunologia e infezioni

Recording Multicellular Behavior in Myxococcus xanthus Biofilms using Time-lapse Microcinematography

A swarm of the &delta;-proteobacterium Myxococcus xanthus contains millions of cells that act as a collective, coordinating movement through a series of signals to create complex, dynamic patterns as a response to environmental cues. These patterns are self-organizing and emergent; they cannot be predicted by observing the behavior of the individual cells. Using a time-lapse microcinematography tracking assay, we identified a distinct emergent pattern in M. xanthus called chemotaxis, defined as the directed movement of a swarm up a nutrient gradient toward its source 1.
In order to efficiently characterize chemotaxis via time-lapse microcinematography, we developed a highly modifiable plate complex (Figure 1) and constructed a cluster of 8 microscopes (Figure 2), each capable of capturing time-lapse videos. The assay is rigorous enough to allow consistent replication of quantifiable data, and the resulting videos allow us to observe and track subtle changes in swarm behavior. Once captured, the videos are transferred to an analysis/storage computer with enough memory to process and store thousands of videos. The flexibility of this setup has proven useful to several members of the M. xanthus community.

Recording Multicellular Behavior in Myxococcus xanthus Biofilms using Time-lapse Microcinematography

To study Myxococcus xanthus swarm behavior, we have designed a time-lapse microcinematography protocol that can be modified for different assays. It employs standard growth conditions adapted for microscopy, and yields reproducible results by the use of inexpensive, reusable silicone gaskets. We have used this method to quantify multicellular chemotaxis.

Registrazione Comportamento multicellulari in Myxococcus xanthus Biofilm utilizzando Time-lapse microcinematografia

A swarm of the &delta;-proteobacterium Myxococcus xanthus contains millions of cells that act as a collective, coordinating movement through a series of ...

Biologia

A Semi-quantitative Approach to Assess Biofilm Formation Using Wrinkled Colony Development

Biofilms, or surface-attached communities of cells encapsulated in an extracellular matrix, represent a common lifestyle for many bacteria. Within a biofilm, bacterial cells often exhibit altered physiology, including enhanced resistance to antibiotics and other environmental stresses 1. Additionally, biofilms can play important roles in host-microbe interactions. Biofilms develop when bacteria transition from individual, planktonic cells to form complex, multi-cellular communities 2. In the laboratory, biofilms are studied by assessing the development of specific biofilm phenotypes. A common biofilm phenotype involves the formation of wrinkled or rugose bacterial colonies on solid agar media 3. Wrinkled colony formation provides a particularly simple and useful means to identify and characterize bacterial strains exhibiting altered biofilm phenotypes, and to investigate environmental conditions that impact biofilm formation. Wrinkled colony formation serves as an indicator of biofilm formation in a variety of bacteria, including both Gram-positive bacteria, such as Bacillus subtilis 4, and Gram-negative bacteria, such as Vibrio cholerae 5, Vibrio parahaemolyticus 6, Pseudomonas aeruginosa 7, and Vibrio fischeri 8.
The marine bacterium V. fischeri has become a model for biofilm formation due to the critical role of biofilms during host colonization: biofilms produced by V. fischeri promote its colonization of the Hawaiian bobtail squid Euprymna scolopes 8-10. Importantly, biofilm phenotypes observed in vitro correlate with the ability of V. fischeri cells to effectively colonize host animals: strains impaired for biofilm formation in vitro possess a colonization defect 9,11, while strains exhibiting increased biofilm phenotypes are enhanced for colonization 8,12. V. fischeri therefore provides a simple model system to assess the mechanisms by which bacteria regulate biofilm formation and how biofilms impact host colonization.
In this report, we describe a semi-quantitative method to assess biofilm formation using V. fischeri as a model system. This method involves the careful spotting of bacterial cultures at defined concentrations and volumes onto solid agar media; a spotted culture is synonymous to a single bacterial colony. This 'spotted culture' technique can be utilized to compare gross biofilm phenotypes at single, specified time-points (end-point assays), or to identify and characterize subtle biofilm phenotypes through time-course assays of biofilm development and measurements of the colony diameter, which is influenced by biofilm formation. Thus, this technique provides a semi-quantitative analysis of biofilm formation, permitting evaluation of the timing and patterning of wrinkled colony development and the relative size of the developing structure, characteristics that extend beyond the simple overall morphology.

We provide a simple, semi-quantitative method to investigate biofilm formation in vitro. This method takes advantage of the Zeiss stemi 2000-C Dissecting Microscope (with camera attachment) to monitor both the timing and pattern of biofilm formation, as assessed by the development of wrinkled colonies.

Un approccio semi-quantitativo per valutare la formazione di biofilm mediante lo sviluppo spiegazzato Colony

Biofilms, or surface-attached communities of cells encapsulated in an extracellular matrix, represent a common lifestyle for many bacteria. Within a ...

Kinetic Visualization of Single-Cell Interspecies Bacterial Interactions

Polymicrobial communities are ubiquitous in nature, yet studying their interactions at the single-cell level is difficult. Thus, a microscopy-based method has been developed for observing interspecies interactions between two bacterial pathogens. The use of this method to interrogate interactions between a motile Gram-negative pathogen, Pseudomonas aeruginosa and a non-motile Gram-positive pathogen, Staphylococcus aureus is demonstrated here. This protocol consists of co-inoculating each species between a coverslip and an agarose pad, which maintains the cells in a single plane and allows for visualization of bacterial behaviors in both space and time.
Furthermore, the time-lapse microscopy demonstrated here is ideal for visualizing the early interactions that take place between two or more bacterial species, including changes in bacterial species motility in monoculture and in coculture with other species. Due to the nature of the limited sample space in the microscopy setup, this protocol is less applicable for studying later interactions between bacterial species once cell populations are too high. However, there are several different applications of the protocol which include the use of staining for imaging live and dead bacterial cells, quantification of gene or protein expression through fluorescent reporters, and tracking bacterial cell movement in both single species and multispecies experiments.

This live-bacterial cell imaging protocol allows for visualization of interactions between multiple bacterial species at the single-cell level over time. Time-lapse imaging allows for observation of each bacterial species in monoculture or coculture to interrogate interspecies interactions in multispecies bacterial communities, including individual cell motility and viability.

Visualizzazione cinetica delle interazioni batteriche interspecie a uni cell

Polymicrobial communities are ubiquitous in nature, yet studying their interactions at the single-cell level is difficult. Thus, a microscopy-based method ...

Preparation, Imaging, and Quantification of Bacterial Surface Motility Assays

Bacterial surface motility, such as swarming, is commonly examined in the laboratory using plate assays that necessitate specific concentrations of agar and sometimes inclusion of specific nutrients in the growth medium. The preparation of such explicit media and surface growth conditions serves to provide the favorable conditions that allow not just bacterial growth but coordinated motility of bacteria over these surfaces within thin liquid films. Reproducibility of swarm plate and other surface motility plate assays can be a major challenge. Especially for more &#8220;temperate swarmers&#8221; that exhibit motility only within agar ranges of 0.4%-0.8% (wt/vol), minor changes in protocol or laboratory environment can greatly influence swarm assay results. &#8220;Wettability&#8221;, or water content at the liquid-solid-air interface of these plate assays, is often a key variable to be controlled. An additional challenge in assessing swarming is how to quantify observed differences between any two (or more) experiments. Here we detail a versatile two-phase protocol to prepare and image swarm assays. We include guidelines to circumvent the challenges commonly associated with swarm assay media preparation and quantification of data from these assays. We specifically demonstrate our method using bacteria that express fluorescent or bioluminescent genetic reporters like green fluorescent protein (GFP), luciferase (lux operon), or cellular stains to enable time-lapse optical imaging. We further demonstrate the ability of our method to track competing swarming species in the same experiment.

Swarming motility is influenced by physical and environmental factors. We describe a two-phase protocol and guidelines to circumvent the challenges commonly associated with swarm assay preparation and data collection. A macroscopic imaging technique is employed to obtain detailed information on swarm behavior that is not provided by current analysis techniques.

Preparazione, Imaging, e la quantificazione di Surface batterica motilità Assays

Bacterial surface motility, such as swarming, is commonly examined in the laboratory using plate assays that necessitate specific concentrations of agar ...

Biophysical Characterization of Flagellar Motor Functions

The role of flagellar motors in bacterial motility and chemotaxis is well-understood. Recent discoveries suggest that flagellar motors are able to remodel in response to a variety of environmental stimuli and are among the triggers for surface colonization and infections. The precise mechanisms by which motors remodel and promote cellular adaptation likely depend on key motor attributes. The photomultiplier-based bead-tracking technique presented here enables accurate biophysical characterization of motor functions, including adaptations in motor speeds and switch-dynamics. This approach offers the advantage of real-time tracking and the ability to probe motor behavior over extended durations. The protocols discussed can be readily extended to study flagellar motors in a variety of bacterial species.

Recent findings suggest that bacterial flagellar motors sense a variety of environmental signals and remodel in response. The bead-assays discussed here are expected to help explain the role of remodeling in cellular adaptation to environmental stressors.

Caratterizzazione biofisica delle funzioni flagellare a motore

The role of flagellar motors in bacterial motility and chemotaxis is well-understood. Recent discoveries suggest that flagellar motors are able to remodel ...

Time-lapse Imaging of Bacterial Swarms and the Collective Stress Response

Swarming is a form of surface motility observed in many bacterial species including Pseudomonas aeruginosa and Escherichia coli. Here, dense populations of bacteria move over large distances in characteristic tendril-shaped communities over the course of hours. Swarming is sensitive to several factors including medium moisture, humidity, and nutrient content. In addition, the collective stress response, which is observed in P. aeruginosa that are stressed by antibiotics or bacteriophage (phage), repels swarms from approaching the area containing the stress. The methods described here address how to control the critical factors that affect swarming. We introduce a simple method to monitor swarming dynamics and the collective stress response with high temporal resolution using a flatbed document scanner, and describe how to compile and perform a quantitative analysis of swarms. This simple and cost-effective method provides precise and well-controlled quantification of swarming and may be extended to other types of plate-based growth assays and bacterial species.

We detail a simple method to produce high-resolution time-lapse movies of Pseudomonas aeruginosa swarms that respond to bacteriophage (phage) and antibiotic stress using a flatbed document scanner. This procedure is a fast and simple method for monitoring swarming dynamics and may be adapted to study the motility and growth of other bacterial species.

L'imaging time-lapse di sciami batterici e la risposta allo stress collettivo

Swarming is a form of surface motility observed in many bacterial species including Pseudomonas aeruginosa and Escherichia coli. Here, dense populations ...

Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series

Motility is crucial to the survival and success of many bacterial species. Many methodologies exist to exploit motility to understand signaling pathways, to elucidate the function and assembly of flagellar parts, and to examine and understand patterns of movement. Here we demonstrate a combination of three of these methodologies. Motility in soft agar is the oldest, offering a strong selection for isolating gain-of-function suppressor mutations in motility-impaired strains, where motility is restored through a second mutation. The cell-tethering technique, first employed to demonstrate the rotary nature of the flagellar motor, can be used to assess the impact of signaling effectors on the motor speed and its ability to switch rotational direction. The &#8220;border-crossing&#8221; assay is more recent, where swimming bacteria can be primed to transition into moving collectively as a swarm. In combination, these protocols represent a systematic and powerful approach to identifying components of the motility machinery, and to characterizing their role in different facets of swimming and swarming. They can be easily adapted to study motility in other bacterial species.

Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series

Many bacteria use flagella-driven motility to navigate their environment and colonize favorable surroundings both individually and as a collective. Demonstrated here is the use of three established methods that exploit motility as a selection tool to identify components/pathways contributing to swimming and swarming motility.

Investigare la motilità guidata dalla Flagella in Escherichia coli applicando tre tecniche consolidate in una serie

Motility is crucial to the survival and success of many bacterial species. Many methodologies exist to exploit motility to understand signaling pathways, ...

Visualizzazione di Spasmi motilità e caratterizzazione del ruolo del

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