Este estudio fue apoyado por el Departamento de Agricultura de Estados Unidos, Servicio de Investigación Agrícola. nombres comerciales o productos comerciales en esta publicación se mencionan únicamente con el propósito de proporcionar información específica y no implica ninguna recomendación o aprobación por el Departamento de Agricultura de los Estados Unidos. USDA es un proveedor y empleador que ofrece igualdad de oportunidades.

1. El periférico de la franja de la colonia bacteriana <ol><li> Crecer X. fastidiosa (XF) Temecula tipo salvaje 22, Pilg supresión mutante Xf ΔpliG (usando la estrategia descrita previamente deleción 23), y su complementario XfΔpliG -C (utilizando anteriormente descrito estrategia de complementación genética basada en el cromosoma 24) en placas de agar medio PD2 25 a los 28 ° C durante 5-7 días. </li><li> Celofán Autoclave (1 x 1 cm 2) en agua a 121 ° C (249 ° F) durante 15 min. Recoger una pieza de celofán, drenar el agua tocando una esquina de celofán en un plato de Petri vacía, coloque cuidadosamente el celofán más del 15% de la superficie del agar y secar al aire. </li><li> Recoge individuo X. colonias fastidiosa con palillos de dientes redondeados y células contado estéril asépticamente en una hoja de papel de celofán esterilizada superpuesto al 15% de la superficie de agar en las placas de agar. Se incuba la placas a 28 ° C durante 2-3 días. </li><li> Examinar la morfología borde de las colonias utilizando un microscopio de disección con una lente de objetivo 2X y una lente ocular 10X. Fotografiar la franja periférica alrededor de las colonias. </li></ol> 2. Microscopía y cámaras de flujo de microfluidos <ol><li> Fabricar dispositivos microfluídicos utilizando procedimientos fotolitográficas similares a los descritos previamente 5,18. Diseñar cuatro canales paralelos con el software de diseño asistido por ordenador sobre la oblea de silicio maestro con las técnicas litográficas estándar 26. </li><li> Crear las cámaras de microfluidos de maestro oblea de silicio con polidimetilsiloxano (PDMS). Verter PDMS no polimerizados sobre el master oblea de silicio y curarlo a 60 ° C durante 1 hr. Despegar la réplica de PDMS del maestro oblea y recortar la réplica de PDMS con una cuchilla en un 22 mm x 40 mm como el mismo tamaño de un cubreobjetos de vidrio. </li><li> Exponer la réplica de PDMS, un cubreobjetos de vidrio (22 x 40 mm 2), y un Microscdiapositiva OPE (51 x 76 mm 2) de plasma de aire a 30 W durante 2 min 27. Sandwich del cuerpo PDMS entre el cubreobjetos de vidrio y el vidrio para microscopio para construir la cámara de uidic fl micro. </li><li> Perforar un agujero (5,5 mm de diámetro) a través de los PDMS en cada extremo de la canal con patrón. Cortar el tubo de goma de silicona en 12-20 cm de largo. Inserte un extremo del tubo de goma de silicona (5,1 mm de diámetro exterior, 2,1 mm de diámetro interior, pared de 0,8 mm) en cada extremo de la apertura de los canales de la réplica de PDMS, y sellarlo con PDMS no polimerizadas a 60 ° C durante 1 hora. </li><li> Conectar otro extremo de la tubería en el extremo de púas de conectores luer de plástico. Envolver las cámaras de microfluidos ensamblados con la hoja de aluminio y esterilizar en autoclave durante 20 min. </li><li> Recoger las bacterias células de X. fastidiosa tipo salvaje, mutante Xf ΔpliG, y complementaria XfΔpliG -C mediante raspado, mediante inoculación desechable bucles de PD2 placas de medio. Ajuste densidad celulara una densidad óptica de 0,05 a 600 nm en caldo PD2 como se describió anteriormente 23. Recoger la solución de células bacterianas en una jeringa de 1 ml Gastight. </li><li> Montar el dispositivo de microfluidos en una platina del microscopio invertido. Conectar un tubo de entrada a la jeringa Gastight 5 ml que contenía caldo PD2. Montar el 5 ml Gastight jeringa con las bombas de jeringa. </li><li> Conectar el tubo de salida a un depósito de residuos. Mantener un caudal medio de 0,2 min -1 l durante 30 min para estabilizar el sistema. </li><li> Conectar los tubos del lado de entrada a un 1 ml de la jeringa que contiene la solución Gastight célula bacteriana. Lavar la solución de células de bacterias a través del tubo de goma hasta que se alcanza el canal. Mantener un caudal medio de 0,2 l min -1 durante otros 30 minutos con el fin de eliminar las células no unidas de la cámara antes de la captura de imágenes. </li><li> Montar el obturador microscopio bajo la parte ajustada campo del microscopio para controlar la luz. Conectar el obturador a la co obturadorntrol sistema y conectar el sistema de control del obturador a la computadora. </li><li> Montar una cámara digital al puerto de vídeo del microscopio y conectarlo a la computadora. Ejecutar el software de grabación de lapso de tiempo, seleccione la función &quot;disparador&quot; del menú, y reconocer automáticamente el obturador instalado por defecto en el software para establecer conexiones con el obturador con el software. </li><li> Seleccione la función &quot;cámara digital&quot; en el menú del software de grabación de lapso de tiempo para reconocer automáticamente la cámara digital como dispositivo de captura por defecto en el software y establecer comunicación con la cámara digital con el software. </li><li> Localizar las células bacterianas en uno de los canales usando 20X óptica de contraste de fase, luego cambiar a la lente objetivo de 40X antes de la captura de imágenes. </li><li> Ejecutar el software de grabación de lapso de tiempo, seleccione la función &quot;adquisición de imágenes&quot; usando los parámetros por defecto en el menú para adquirir las imágenes del microscopio.A continuación, abra la función &quot;Adquirir lapso de tiempo&quot; y establecer el intervalo de tiempo de 30 seg 5,18,28 por la duración de 6-24 h según el experimento necesario para observar espasmos motilidad de X. fastidiosa 5,18,28. Haga clic en &quot;OK&quot; para iniciar la grabación de lapso de tiempo. Haga clic en &quot;Función de pila&quot; del menú, seleccione &quot;Guardar como&quot; para apilar las imágenes de la carpeta de destino en el equipo después de finalizar la grabación. </li><li> Para múltiples canales, la captura de imágenes con lapso de tiempo desde el primer canal cada 30 segundos durante 6 horas. Mover la lente del objetivo del microscopio para el siguiente canal para localizar las células diana. Repita la función de lapso de tiempo como se describió anteriormente para capturar imágenes en cada uno de cuatro canales secuencialmente si experimento está configurado para utilizar cuatro canales. Continuar la captura de la imagen de lapso de tiempo de hasta tres días consecutivos. Todos los experimentos se realizaron a temperatura ambiente (23 ± 2 ° C). </li><li> Compilar las imágenes con lapso de tiempo en unaarchivo de vídeo utilizando el software de imágenes de la grabación de lapso de tiempo. ejecutar el software de grabación de lapso de tiempo, haga clic en &quot;Función de pila&quot; en el menú, y seleccione &quot;función de pila abierta&quot; para abrir los archivos apilados desde el ordenador. </li><li> Iniciar la función &quot;Crear película&quot; desde el módulo de pila, la selección de todas las imágenes y elegir el formato de salida &quot;AVI&quot;. Haga clic en &quot;Guardar como&quot; para guardar el archivo de vídeo en la carpeta de destino en el equipo. </li><li> Seleccione las películas elaboradas a partir de la carpeta de destino en el ordenador y reproducirlos. A continuación, observar la motilidad de las células individuales a través de la visualización resultante de la actividad espasmos motilidad de las células de bacterias en los archivos de vídeo generados. </li></ol>

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Los autores declaran que no tienen intereses financieros en competencia.

En este estudio, hemos caracterizado el comportamiento de movimiento de X. fastidiosa Pilg mutante Xf ΔpilG y sus complementarias cepas XfΔpilG- C de nuevo diseño en-nano-canales paralelos múltiples cámaras micro fl uidic. Las cámaras uidic de nuevo diseño micro FL puede tener hasta cuatro cámaras paralelas con 100 micras nano-canal de ancho en comparación con diseños anteriores con solo un 50 micras de ancho del canal 18. Cuanto más amplia sea la nano-c...

Xylella fastidiosa es una bacteria Gram-negativa no flagelado, patógeno que causa una serie de enfermedades de los cultivos económicamente importantes, incluyendo la enfermedad de Pierce en la vid (Vitis vinifera L.) 1,2, 3. Esta bacteria se limita a la xilema conductor de agua vasos. La infección de la vid provoca la obstrucción de los vasos del xilema y resulta en estrés hídrico y las deficiencias nutricionales 3. La colonización exitosa depende de la capacidad de la bacteria para moverse desde el sitio inicial de la infección con el resto de la planta 3. Contracciones la motilidad es un medio de movimiento flagelar bacteriano-independiente a través de la extensión, el apego y la retracción de la IV pili de tipo polar 4 que se ha caracterizado en X. 5,6,7 fastidiosa. La motilidad espasmos ha sido observado por pinzas láser y microscopía de fuerza atómica (AFM) 8,9,10. Utilizando estas técnicas, tmotilidades witching generado por tipo IV pilus de N. gonorrhoeae y P. aeruginosa se ​​caracteriza por fl pili etiquetado uorescently y la captura de sus movimientos al microscopio. Aunque ambos métodos han detallado la fuerza de adhesión de las bacterias individuales, los procedimientos son complicados y consume mucho tiempo 9,10. Las cámaras uidic fl micro se utilizaron para observar la migración de larga distancia de las células individuales, así como pequeños agregados de células bacterianas 5,6. Estas cámaras se han diseñado como un nano-canal microfabricado en una placa integrada con un lapso de tiempo 11,12,13,14 sistema de grabación de imágenes. Micro fl dispositivos de cámara uidic ofrecen varias ventajas para el estudio de la conducta y el movimiento de célula a célula interacciones de las bacterias: (i) Proporciona una plataforma integrada que tiene múltiples capacidades de canal; (Ii) le corresponde examinar las mociones y agregaciones de células individuales en las características de escala nanométrica de las bacterias; (Iii) que permite m directaicroscopic grabación de imágenes de las células bacterianas y realizar un análisis cronológico, (iv) que proporciona observaciones espaciales y temporales a largo plazo de las poblaciones individuales y / o de bacterias en un micro-ambiente; (V) la velocidad de flujo de medio de cultivo en un canal puede ser controlada con precisión y es necesario (vi) solamente un volumen muy pequeño (1 ml) de medio de cultivo para cada experimento. Recientemente, la micro fl uidic flujo sistema se ha empleado para investigar el comportamiento de las células bacterianas bajo diversos microambientes 14,15,16. La adhesividad y el accesorio de superficie de E. coli 15, X. fastidiosa 16, y Acidovorax citrulli 14 a las superficies de vidrio se evaluaron utilizando cámaras uidic micro fl. La formación de agregación y bio fi lm mediada por pili de tipo IV de Acidovorax citrulli se analizaron 14. Además, el movimiento de A. citrulli observó bajo flujo condiciones demostraron que los pili de tipo IV puede desempeñar un papel importante en la colonización y la propagación de A. citrulli en los vasos del xilema savia bajo condiciones de flujo. Las contracciones motilidades de Pseudomonas aeruginosa y X. fastidiosa células se observaron con éxito contra una corriente de fluido en una cámara de flujo microfabricado 5,6,17. Tipo IV pilus deficiente PilB y pilQ mutantes de X. fastidiosa se ​​encontraron a alterar profundamente la velocidad de la motilidad espasmos en las condiciones de fluencia en dispositivos micro fl uidic 5,6,18. Los estudios realizados sobre la adhesión bacteriana y la motilidad en dispositivos uidic fl micro indicaron que las cámaras uidic micro fl son particularmente adecuados para el análisis de la motilidad espasmos y la migración de bacterias mediada por pili in vitro. Estos resultados explican el mecanismo de la migración mediada por contracciones que facilita la fijación célula-célula, la agregación y la colonización dentro deel anfitrión, eventualmente conducir a la infección sistémica. Pil-CHP operón de X. fastidiosa contiene Pilg, Pili, pilJ, píldora, chpB y CHPC el que la transducción de señales codifican las vías 20. Los quimiorreceptores transmembrana se unen estímulos químicos en el dominio periplásmico y activan una cascada de señalización en su porción citoplasmática de controlar en última instancia, la motilidad bacteriana espasmos. En el operón pil-CHP de X. fastidiosa, una proteína Pilg fosfo-lanzadera es un homólogo de CheY. En E. coli y P. aeruginosa, CheY es el regulador de la respuesta de quimiotaxis en los sistemas que interactúan con las proteínas motoras flagelos 19, 21. A pesar de las contribuciones del operón pil-CHP hacia la virulencia en X. fastidiosa se ​​examinaron recientemente 20, el papel de Pilg en operón quimiotaxis en respuesta a las señales del medio ambiente y para regulada / motor de tipo IV pili de X. fastidiosa es uncLear. Para dilucidar la visión del regulador de la quimiotaxis Pilg en la actividad de la motilidad espasmos de X. fastidiosa, una cámara de uidic fl micro se utiliza para evaluar la motilidad espasmos de X. fastidiosa. El Pilg de X. fastidiosa se ​​caracteriza mediante la comparación de los fenotipos de un mutante de deleción Xf ΔpliG, cepa complementaria XfΔpliG -C y su tipo salvaje in vitro. Los resultados ponen de manifiesto el papel de Pilg en la motilidad espasmos de 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 es una bacteria no flagelado Gram-negativa que provoca una serie de enfermedades económicamente importantes de plantas. La motilidad espasmos ofrece X. fastidiosa un medio para el movimiento de larga distancia dentro de la planta y la colonización, que contribuye a la patogenicidad en X. fastidiosa. La motilidad espasmos de X. fastidiosa es operado por pili de tipo IV. Pili de tipo IV de Xylella fastidiosa están regulados por Pilg, un regulador de la quimiotaxis de Pil-CHP proteínas operón codificación que están involucrados con las vías de transducción de señales. Para dilucidar el papel de los Pilg en la motilidad espasmos de X. fastidiosa, una Pere-deficiente mutante Xf ΔpilG y su cepa complementaria XfΔpilG- C que contiene nativa Pilg se desarrollaron. A las cámaras de microfluidos integrados con un sistema de grabación de la imagen de lapso de tiempo fue utilizado para observar la motilidad espasmos en XfΔpIlg, XfΔpilG- C y su cepa de tipo salvaje. El uso de este sistema de grabación, que permite observaciones espaciales y temporales a largo plazo de la agregación, la migración de las células y las poblaciones de bacterias a través de la motilidad espasmos individuales. X. de tipo salvaje y fastidiosa cepa complementaria XfΔpilG- C mostraron características típicas contracciones de la motilidad observados directamente en las cámaras de flujo de microfluidos, mientras que el mutante XfΔpliG exhibe el fenotipo deficiente espasmos. Este estudio demuestra que Pilg contribuye a la motilidad espasmos de X. fastidiosa. La cámara de flujo de microfluidos se utiliza como un medio para la observación de la motilidad espasmos.

La presencia de una franja periférica colonia indicativo de tipo IV pilus mediada motilidad espasmos, se observó en las colonias de X. de tipo salvaje y fastidiosa cepa Xf ΔpliG -C complementaria (Figura 1). Mutant XfΔpliG, sin embargo, no presentó una franja alrededor de la periferia de las colonias (Figura 1). Time-lapse de las células bacterianas en cámaras de flujo nano-microfluidos reveló que cris...

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

En este estudio, se empleó una cámara de flujo nano-microfluidos de visualizar y caracterizar funcionalmente la motilidad espasmos de Xylella fastidiosa, una bacteria que causa la enfermedad de Pierce en la vid.

La visualización de Contracciones Motilidad y caracterización del papel de la<em&gt; Pilg</em&gt; en<em&gt; Xylella fastidiosa</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 vistas.  University of California, Davis.  En este estudio, se empleó una cámara de flujo nano-microfluidos de visualizar y caracterizar funcionalmente la motilidad espasmos de Xylella fastidiosa, una bacteria que causa la enfermedad de Pierce en la vid. 

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.

Imágenes en vivo de la célula de fluorescencia de ciclo completo de células vegetativas de la lento-crecimiento Social bacteria 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 ...

Investigación

Bioquímica

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.

Establecimiento de pez cebra Larval como modelo Animal para investigar Trypanosoma cruzi motilidad En Vivo

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

Biología del Desarrollo

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.

Generación y multi-fenotípicos cribado de alto contenido de<em&gt; Coxiella burnetii</em&gt; transposón mutantes

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

Inmunología e Infección

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.

Registro del comportamiento multicelular en Myxococcus xanthus Las biopelículas con 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 ...

Biología

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 enfoque semi-cuantitativo para evaluar la formación de biopelículas Con el desarrollo de colonias arrugada

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.

Visualización cinética de interacciones bacterianas entre especies de una sola célula

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.

Preparación, Imaging, y cuantificación de la superficie bacteriana Motilidad ensayos

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.

Caracterización biofísica de las funciones de motor flagelar

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.

Imágenes de lapso de tiempo de enjambres bacterianos y la respuesta colectiva al estrés

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.

Investigación De La Motilidad Impulsada Por Flagelos En Escherichia coli mediante la Aplicación De Tres Técnicas Establecidas En Una Serie

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

La visualización de Contracciones Motilidad y caracterización del papel de la

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