Los autores desean reconocer que este trabajo recibió el apoyo de las Ciencias Naturales e Ingeniería de Investigación de Canadá (NSERC) subvención.

<ol>
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Y., Wallace, A., Nguyen, J., Mohler, W. A., Soto, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=UNC-40/DCC,+SAX-3/Robo,+and+VAB-1/Eph+polarize+F-actin+during+embryonic+morphogenesis+by+regulating+the+WAVE/SCAR+actin+nucleation+complex.">UNC-40/DCC, SAX-3/Robo, and VAB-1/Eph polarize F-actin during embryonic morphogenesis by regulating the WAVE/SCAR actin nucleation complex.</a> PLoS Genet. 8, (2012).</li><li>Piekny, A. J., Werner, M., Glotzer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytokinesis:+welcome+to+the+Rho+zone.">Cytokinesis: welcome to the Rho zone.</a> Trends Cell Biol. 15, 651-658 (2005).</li><li>Piekny, A. J., Maddox, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+myriad+roles+of+Anillin+during+cytokinesis.">The myriad roles of Anillin during cytokinesis.</a> Sem. Cell Dev. Biol. 21, 881-891 (2010).</li><li>Zhao, W. M., Fang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anillin+is+a+substrate+of+anaphase-promoting+complex/cyclosome+(APC/C)+that+controls+spatial+contractility+of+myosin+during+late+cytokinesis.">Anillin is a substrate of anaphase-promoting complex/cyclosome (APC/C) that controls spatial contractility of myosin during late cytokinesis.</a> J. Biol. Chem. 280, 33516-33524 (2005).</li><li>Piekny, A. J., Glotzer, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anillin+is+a+scaffold+protein+that+links+RhoA,+actin+and+myosin+during+cytokinesis.">Anillin is a scaffold protein that links RhoA, actin and myosin during cytokinesis.</a> Curr. Biol. 18, 30-36 (2008).</li><li>Hickson, G. R., O&#8217;Farrell, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rho-dependent+control+of+anillin+behavior+during+cytokinesis.">Rho-dependent control of anillin behavior during cytokinesis.</a> J. Cell Biol. 180, 285-294 (2008).</li><li>Fraser, A. G., Kamath, R. 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Los autores no tienen nada que revelar.

Este protocolo describe el uso de diversos tipos de microscopía de divisiones celulares imagen durante mediados embriogénesis. En particular, este protocolo pone de relieve cómo la imagen de la división de los neuroblastos, células que pueden facilitar la morfogénesis epidérmica. La comunicación de célula de la célula es importante para la formación de tejido durante el desarrollo de los metazoos y C. elegans es un modelo excelente para estudiar la formación de tejido in vivo. Un evento que...

Aunque existen protocolos que describen cómo la división celular la imagen a principios del C. elegans embrión, este protocolo se describe cómo la división celular la imagen dentro de un tejido a mediados embriogénesis. Uno de los principales retos en la formación de imágenes organismos durante el desarrollo ha sido su sensibilidad a la fototoxicidad. Sin embargo, el aumento de la accesibilidad a hilar microscopios confocal de disco o microscopios de campo de barrido ha permitido aplicaciones de imagen más extendidos. Ambos sistemas utilizan láseres de estado sólido y la luz difusa, lo que limita los niveles de radiación UV que los organismos están expuestos. Sin embargo, puestos de campo amplio todavía se puede utilizar para obtener imágenes in vivo, sobre todo si están equipados con cámaras con alta sensibilidad (por ejemplo EMCCD), control de apertura y control de luz (por ejemplo, LEDs o bombillas de mercurio ajustables). Este protocolo describe cómo utilizar bien un sistema confocal o basado en un sistema de campo amplio para la división celular en el desarrollo de la imagen C. elegans &lt;/ Em&gt; embriones. A modo de ejemplo, se describe cómo reproducir la división celular neuroblastos. Los neuroblastos pueden facilitar la morfogénesis epidérmica proporcionando señales químicas o mecánicas a las células de la epidermis suprayacente, y proporcionar un excelente ejemplo de la importancia de la comunicación intercelular en la formación de tejidos. Caenorhabditis elegans es un organismo modelo ideal para estudios basados ​​en la microscopía, debido a su transparencia y simple organización del tejido 1. Además, C. elegans es susceptible de métodos genéticos y de ARNi, y dado que muchos de sus genes tienen homólogos humanos, puede ser utilizado para identificar los mecanismos conservadas para la formación de tejido 2-5. En C. elegans, la formación de la epidermis ocurre durante la mitad la embriogénesis, cuando el embrión tiene&gt; 300 células. Morfogénesis epidérmico se compone de varias fases principales, durante el cual el embrión está encerrado en una capa de células epidérmicas que constriñen y se extienden para transformar la EMBRyo desde una forma ovoide en la forma alargada de un tornillo sin fin 6. Recinto ventral describe uno de estos eventos morfogenéticos, cuando las células epidérmicas ventrales migran hacia la línea media ventral para cubrir la superficie ventral del embrión (Figura 1). En primer lugar, dos pares de anteriores situada células principales del borde migran hacia la línea media ventral, donde se adhieren y se fusionan con sus vecinos contralaterales 6. Esto es seguido por la migración de las células de bolsillo posterior situado, que forman cuña formas creando un bolsillo ventral 6-7. El mecanismo que cierra el bolsillo no se entiende bien. Una posibilidad es que una estructura contráctil miosina actina supracellular ata las células de bolsillo juntos en un cordón de bolsa como la moda, similar a la cicatrización de la herida 8. Curiosamente, la migración de algunas de las células de bolsillo está mediada por subconjuntos específicos de neuroblastos subyacentes 9 (precursores neuronales que se encuentran debajo de la epidermis; Figura 1B). Estudios anteriores mostraron que los neuroblastos regulan la migración de las células epidérmicas ventrales y recinto ventral. VAB-1 (receptor de Efrina) y VAB-2 (Efrina ligando) son altamente expresado en los neuroblastos y facilitar la clasificación de los neuroblastos anterior y posterior entre sí, y mutaciones en VAB-1 o VAB-2 causa recinto ventral fenotipos 10-13. Sin embargo, experimentos de rescate promotoras mostraron que también se requiere VAB-1 en las células epidérmicas ventrales suprayacentes y receptores para otras señales de orientación secretadas por los neuroblastos se expresan en las células epidérmicas ventrales 9. Aunque las mutaciones en cualquiera de estos receptores causan fenotipos recinto ventrales, no está claro si surgen defectos debido a problemas en el posicionamiento de los neuroblastos o por insuficiencia de las células epidérmicas ventrales para responder a la orientación Tacos de 14. La alteración de la división de wi neuroblastosthout que afecta su capacidad para secretar señales de orientación podría arrojar luz sobre el papel de los neuroblastos y su capacidad para proporcionar energía mecánica durante la morfogénesis epidérmica. Recientemente, se encontró que un gen de la división celular, ani-1 (anillin) es altamente expresado en los neuroblastos (figura 2A) y su agotamiento causa defectos de división de neuroblastos. Curiosamente, estos embriones exhiben fenotipos recinto ventrales (Fotopoulos, Wernike y Piękny, observaciones no publicadas). Anillin se requiere para la división celular, y en particular para la citocinesis, que describe el proceso en el que una célula madre divide físicamente en dos células hijas. La citocinesis es impulsado por la formación de un anillo contráctil actomiosina, que debe ser estrechamente controlada en el espacio y el tiempo para asegurarse de que está acoplado correctamente con la segregación de cromátidas hermanas. El regulador maestro de la citocinesis metazoos es RhoA (RHO-1 en C. elegans), una pequeña GTPasa que es unctive en su forma unida a GTP. El FMAM Ect2/ECT-2 activa RhoA, después de lo cual RhoA-GTP interactúa con los efectores que forman el anillo contráctil y median su ingresión 15. Anillin es una proteína de dominio múltiple que se une a RhoA a través de su C-terminal y a la actina y la miosina a través de su extremo N-terminal. Anillin se requiere para estabilizar la posición del anillo contráctil en células de mamífero o de Drosophila S2 16. Agotamiento Anillin causa anillos contráctiles a someterse a oscilaciones laterales, y la citocinesis finalmente falla la formación de células multinucleadas 17-19. Curiosamente, a pesar C. elegans ani-1 coordina la contractilidad actomiosina en el embrión temprano, no es esencial para la citocinesis. Sin embargo, como se describió anteriormente, se requiere ani-1 para la citocinesis neuroblastos durante la mitad de la embriogénesis (Fotopoulos, Wernike y Piękny, observaciones no publicadas). Fracaso Citocinesis alteraría el número y posición de los neuroblastos y podría afectar a la locción de señales de orientación químicos, o podría alterar las propiedades mecánicas del tejido. Ambos modelos destacan el papel no autónoma de neuroblastos de cerramiento ventral, y la importancia de la comunicación de tejidos tejidos durante el desarrollo embrionario. Este protocolo experimental se describe cómo la división celular imagen durante la C. elegans mediados embriogénesis mediante microscopía de fluorescencia. La mayoría de los experimentos que estudian los mecanismos de la división celular se realizaron en células individuales dentro de placas de cultivo (por ejemplo. HeLa o células S2) o en embriones tempranos con un número limitado de células (por ejemplo, C. elegans embrión de una célula, de Xenopus, o equinodermo embriones). Sin embargo, es importante para estudiar la división celular también dentro de los tejidos, ya que hay señales externas que pueden influir en el tiempo y la colocación del plano de división. Además, las células pueden proporcionar señales químicas o mecánicas para influir en el desarrollo de los tejidos vecinoss, y es importante entender cómo la comunicación intercelular ayuda a los tejidos para formar durante el desarrollo.

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			<td height="21" style="height:21px;width:291px;">Agar</td>
			<td style="width:247px;">BioShop Canada Inc.</td>
			<td style="width:185px;">#AGR001.1</td>
			<td style="width:335px;">For making C. elegans NGM and RNAi plates</td>
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			<td height="21" style="height:21px;">Agar</td>
			<td>Bio Basic Inc.</td>
			<td>#9002-18-0</td>
			<td>For making bacteria LB agar plates</td>
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			<td height="21" style="height:21px;">Agarose</td>
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			<td>#AGA001.500</td>
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			<td height="21" style="height:21px;">Anti-mouse Alexa 488 antibody</td>
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			<td>#A11029</td>
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			<td height="21" style="height:21px;">Anti-mouse anti-GFP antibody</td>
			<td>Roche Applied Science</td>
			<td>#11814460001</td>
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			<td height="21" style="height:21px;">Anti-rabbit Alexa 568 antibody</td>
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			<td>#A11011</td>
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			<td height="21" style="height:21px;">Ampicillin</td>
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			<td>Store powder at 4 &#176;C and dissolved ampicillin at -20 &#176;C</td>
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			<td height="21" style="height:21px;">Bactopetone&#160; (peptone-A)</td>
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			<td height="21" style="height:21px;">CaCl2 (calcium chloride)</td>
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			<td height="21" style="height:21px;">DAPI&#160;</td>
			<td>Sigma-Aldrich&#160;</td>
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			<td>Use to stain nucleic acids (DNA)</td>
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			<td height="21" style="height:21px;">IPTG (isopropylthio-&#946;-galactoside)</td>
			<td>Bio Basic Inc.</td>
			<td>#367-93-1</td>
			<td>Store powder and dissolved IPTG at -20 &#176;C</td>
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		<tr height="21">
			<td height="21" style="height:21px;">KH2PO4 (potassium phosphate, monobasic)</td>
			<td>BioShop Canada Inc.</td>
			<td>#PPM666.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">K2HPO4 (potassium phosphate, dibasic)</td>
			<td>BioShop Canada Inc.</td>
			<td>#PPD303.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">L4440&#160; (feeding vector)</td>
			<td>Addgene</td>
			<td>#1654</td>
			<td>Keep as glycerol stock at -80 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MgSO4&#160;&#160; (magnesium sulfate)</td>
			<td>BioShop Canada Inc.</td>
			<td>#MAG511.500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl (sodium chloride)</td>
			<td>Bio Basic Inc.</td>
			<td>#7647-14-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Na2HPO4 (sodium phosphate, dibasic)</td>
			<td>Bio Basic Inc.</td>
			<td>#7558-79-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Normal Donkey Serum (NDS)</td>
			<td>Wisent Bioproducts</td>
			<td>#035-110</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">n-propyl 3.4.5-trihydroxybenzoate (propyl gallate)</td>
			<td>Alfa Aesar</td>
			<td>#A10877</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly-L-lysine</td>
			<td>Sigma-Aldrich&#160;</td>
			<td>#P8920</td>
			<td>For optimal results coat microscope slides three times&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Streptomycin</td>
			<td>BioShop Canada Inc.</td>
			<td>#STP101.50</td>
			<td>Store powder at 4 &#176;C and dissolved streptomycin at -20 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tetracyclin</td>
			<td>BioShop Canada Inc.</td>
			<td>#TET701.10</td>
			<td>Store powder at 4 &#176;C and dissolved tetracycline at -20 &#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tween-20</td>
			<td>Bio Basic Inc.</td>
			<td>CAS#9005-64-5</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tryptone</td>
			<td>BioShop Canada Inc.</td>
			<td>#TRP402.500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Yeast Extract</td>
			<td>Bio Basic Inc.</td>
			<td>#8013-01-2</td>
			<td></td>
		</tr>
	</tbody>
</table>

visualizing neuroblast cytokinesis during c. elegans embryogenesis

Este protocolo describe el uso de microscopía de fluorescencia a la imagen dentro de la división de células en desarrollo Caenorhabditis elegans embriones. En particular, este protocolo se centra en la forma de imagen dividiendo neuroblastos, que se encuentran por debajo de las células de la epidermis y puede ser importante para la morfogénesis epidérmica. La formación de tejidos es crucial para el desarrollo de los metazoos y se basa en las señales externas de los tejidos vecinos. C. elegans es un organismo modelo excelente para estudiar la morfogénesis de tejidos in vivo debido a su transparencia y organización sencilla, haciendo que sus tejidos fácil de estudiar a través de microscopía. Recinto ventral es el proceso donde la superficie ventral del embrión está cubierto por una capa única de células epiteliales. Este evento se piensa que es facilitado por los neuroblastos subyacentes, que proporcionan señales de orientación química para mediar en la migración de las células epiteliales suprayacentes. Sin embargo, los neuroblastos son altamente proliferativa y también pueden actuarcomo un sustrato mecánico para las células epidérmicas ventrales. Los estudios que utilizan este protocolo experimental podrían descubrir la importancia de la comunicación intercelular durante la formación de tejido, y podrían utilizarse para revelar las funciones de los genes implicados en la división celular dentro de los tejidos en desarrollo.

Este protocolo experimental se describe cómo la división celular en la imagen C. elegans embriones durante mediados de la embriogénesis. En particular, se describe cómo los neuroblastos de la imagen, lo que puede facilitar la morfogénesis epidérmica. Morfogénesis epidérmico se produce debido a una combinación de cambios en la forma de células epidérmicas, la migración y la adhesión, pero también se basa en señales químicas o mecánicas de los neuroblastos subyacentes (Figura 1B).</strong...

Watch this Scientific Journal Video about Visualizing Neuroblast Cytokinesis During C. elegans Embryogenesis at JoVE.com

Visualizing Neuroblast Cytokinesis During C. elegans Embryogenesis

Este protocolo describe cómo reproducir la división de células dentro de un tejido en Caenorhabditis elegans embriones. Mientras que varios protocolos describen cómo la división celular imagen en el embrión temprano, este protocolo se describe cómo la imagen de la división celular dentro de un tejido en desarrollo durante la embriogénesis tardía mediados.

Visualizar Neuroblast Citocinesis Durante<em&gt; C. elegans</em&gt; Embriogénesis

This protocol describes the use of fluorescence microscopy to image dividing cells within developing Caenorhabditis elegans embryos. In particular, this ...

visualizing-neuroblast-cytokinesis-during-c-elegans-embryogenesis

Research

JoVE Journal

Neuroscience

Visualizing Neuroblast Cytokinesis During C. elegans Embryogenesis

11.7K vistas.  Concordia University.  Este protocolo describe cómo reproducir la división de células dentro de un tejido en Caenorhabditis elegans embriones. Mientras que varios protocolos describen cómo la división celular imagen en el embrión temprano, este protocolo se describe cómo la imagen de la división celular dentro de un tejido en desarrollo durante la embriogénesis tardía mediados. 

Video: Visualizing Neuroblast Cytokinesis During C. elegans Embryogenesis

Assaying &beta;-amyloid Toxicity using a Transgenic C. elegans Model

Accumulation of the &beta;-amyloid peptide (A&beta;) is generally believed to be central to the induction of Alzheimer's disease, but the relevant mechanism(s) of toxicity are still unclear. A&beta; is also deposited intramuscularly in Inclusion Body Myositis, a severe human myopathy. The intensely studied nematode worm Caenorhabditis elegans can be transgenically engineered to express human A&beta;. Depending on the tissue or timing of A&beta; expression, transgenic worms can have readily measurable phenotypes that serve as a read-out of A&beta; toxicity. For example, transgenic worms with pan-neuronal A&beta; expression have defects is associative learning (Dosanjh et al. 2009), while transgenic worms with constitutive muscle-specific expression show a progressive, age-dependent paralysis phenotype (Link, 1995; Cohen et al. 2006). One particularly useful C. elegans model employs a temperature-sensitive mutation in the mRNA surveillance system to engineer temperature-inducible muscle expression of an A&beta; transgene, resulting in a reproducible paralysis phenotype upon temperature upshift (Link et al. 2003). Treatments that counter A&beta; toxicity in this model [e.g., expression of a protective transgene (Hassan et al. 2009) or exposure to Ginkgo biloba extracts (Wu et al. 2006)] reproducibly alter the rate of paralysis induced by temperature upshift of these transgenic worms. Here we describe our protocol for measuring the rate of paralysis in this transgenic C. elegans model, with particular attention to experimental variables that can influence this measurement.

Assaying &amp;#946;-amyloid Toxicity using a Transgenic C. elegans Model

The intensely studied nematode worm Caenorhabditis elegans can be transgenically engineered to express the human &beta;-amyloid peptide (A&beta;). Induced expression of A&beta; in C. elegans muscle leads to a rapid, reproducible paralysis phenotype that can be used to monitor treatments that modulate A&beta; toxicity.

Ensayo β-amiloide toxicidad con un transgénico C. elegans Modelo

Accumulation of the &beta;-amyloid peptide (A&beta;) is generally believed to be central to the induction of Alzheimer's disease, but the relevant ...

Investigación

Neurociencias

C. elegans Positive Butanone Learning, Short-term, and Long-term Associative Memory Assays

The memory of experiences and learned information is critical for organisms to make choices that aid their survival. C. elegans navigates its environment through neuron-specific detection of food and chemical odors1, 2, and can associate nutritive states with chemical odors3, temperature4, and the pathogenicity of a food source5.
Here, we describe assays of C. elegans associative learning and short- and long-term associative memory. We modified an aversive olfactory learning paradigm6 to instead produce a positive response; the assay involves starving ~400 worms, then feeding the worms in the presence of the AWC neuron-sensed volatile chemoattractant butanone at a concentration that elicits a low chemotactic index (similar to Toroyama et al.7). A standard population chemotaxis assay1 tests the worms' attraction to the odorant immediately or minutes to hours after conditioning.
After conditioning, wild-type animals' chemotaxis to butanone increases ~0.6 Chemotaxis Index units, its "Learning Index". Associative learning is dependent on the presence of both food and butanone during training. Pairing food and butanone for a single conditioning period ("massed training") produces short-term associative memory that lasts ~2 hours. Multiple conditioning periods with rest periods between ("spaced training") yields long-term associative memory (&lt;40 hours), and is dependent on the cAMP Response Element Binding protein (CREB),6 a transcription factor required for long-term memory across species.8
Our protocol also includes image analysis methods for quick and accurate determination of chemotaxis indices. High-contrast images of animals on chemotaxis assay plates are captured and analyzed by worm counting software in MatLab. The software corrects for uneven background using a morphological tophat transformation.9 Otsu's method is then used to determine a threshold to separate worms from the background.10 Very small particles are removed automatically and larger non-worm regions (plate edges or agar punches) are removed by manual selection. The software then estimates the size of single worm by ignoring regions that are above a specified maximum size and taking the median size of the remaining regions. The number of worms is then estimated by dividing the total area identified as occupied by worms by the estimated size of a single worm.
We have found that learning and short- and long-term memory can be distinguished, and that these processes share similar key molecules with higher organisms.6,8 Our assays can quickly test novel candidate genes or molecules that affect learning and short- or long-term memory in C. elegans that are relevant across species.

C. elegans Positive Butanone Learning, Short-term, and Long-term Associative Memory Assays

Here we describe methods to test C. elegans associative learning and short- and long-term associative memory. These population assays employ the worms abilities to chemotax toward volatile odorants, and form positive associations upon pairing food with the chemoattractant butanone. Increasing the number of conditioning periods induces long-term memory.

C. elegans de aprendizaje positivo butanona, a corto plazo y largo plazo Ensayos de la memoria asociativa

The memory of experiences and learned information is critical for organisms to make choices that aid their survival. C. elegans navigates its environment ...

In vivo Laser Axotomy in C. elegans

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron is damaged by injury or disease, it may regenerate. Cell-intrinsic and extrinsic factors influence the ability of a neuron to regenerate and restore function. Recently, the nematode C. elegans has emerged as an excellent model organism to identify genes and signaling pathways that influence the regeneration of neurons1-6. The main way to initiate neuronal regeneration in C. elegans is laser-mediated cutting, or axotomy. During axotomy, a fluorescently-labeled neuronal process is severed using high-energy pulses. Initially, neuronal regeneration in C. elegans was examined using an amplified femtosecond laser5. However, subsequent regeneration studies have shown that a conventional pulsed laser can be used to accurately sever neurons in vivo and elicit a similar regenerative response1,3,7.
We present a protocol for performing in vivo laser axotomy in the worm using a MicroPoint pulsed laser, a turnkey system that is readily available and that has been widely used for targeted cell ablation. We describe aligning the laser, mounting the worms, cutting specific neurons, and assessing subsequent regeneration. The system provides the ability to cut large numbers of neurons in multiple worms during one experiment. Thus, laser axotomy as described herein is an efficient system for initiating and analyzing the process of regeneration.

In vivo Laser Axotomy in C. elegans

A protocol to cut neurons in C. elegans with a MicroPoint pulsed laser is presented. We describe setting up the system, immobilizing worms, and severing labeled neurons. Advantages include a relatively low-cost system and the ability to sever neuronal processes or ablate cells in vivo.

En vivo láser axotomía en C. elegans

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron ...

Time-lapse Imaging of Neuroblast Migration in Acute Slices of the Adult Mouse Forebrain

There is a substantial body of evidence indicating that new functional neurons are constitutively generated from an endogenous pool of neural stem cells in restricted areas of the adult mammalian brain. Newborn neuroblasts from the subventricular zone (SVZ) migrate along the rostral migratory stream (RMS) to their final destination in the olfactory bulb (OB)1. In the RMS, neuroblasts migrate tangentially in chains ensheathed by astrocytic processes2,3 using blood vessels as a structural support and a source of molecular factors required for migration4,5. In the OB, neuroblasts detach from the chains and migrate radially into the different bulbar layers where they differentiate into interneurons and integrate into the existing network1, 6.
In this manuscript we describe the procedure for monitoring cell migration in acute slices of the rodent brain. The use of acute slices allows the assessment of cell migration in the microenvironment that closely resembling to in vivo conditions and in brain regions that are difficult to access for in vivo imaging. In addition, it avoids long culturing condition as in the case of organotypic and cell cultures that may eventually alter the migration properties of the cells. Neuronal precursors in acute slices can be visualized using DIC optics or fluorescent proteins. Viral labeling of neuronal precursors in the SVZ, grafting neuroblasts from reporter mice into the SVZ of wild-type mice, and using transgenic mice that express fluorescent protein in neuroblasts are all suitable methods for visualizing neuroblasts and following their migration. The later method, however, does not allow individual cells to be tracked for long periods of time because of the high density of labeled cells. We used a wide-field fluorescent upright microscope equipped with a CCD camera to achieve a relatively rapid acquisition interval (one image every 15 or 30 sec) to reliably identify the stationary and migratory phases. A precise identification of the duration of the stationary and migratory phases is crucial for the unambiguous interpretation of results. We also performed multiple z-step acquisitions to monitor neuroblasts migration in 3D. Wide-field fluorescent imaging has been used extensively to visualize neuronal migration7-10. Here, we describe detailed protocol for labeling neuroblasts, performing real-time video-imaging of neuroblast migration in acute slices of the adult mouse forebrain, and analyzing cell migration. While the described protocol exemplified the migration of neuroblasts in the adult RMS, it can also be used to follow cell migration in embryonic and early postnatal brains.

We describe a protocol for real-time videoimaging of neuronal migration in the mouse forebrain. The migration of virally-labeled or grafted neuronal precursors was recorded in acute live slices using wide-field fluorescent imaging with a relatively rapid acquisition interval to study the different phases of cell migration, including the durations of the stationary and migration phases and the speed of migration.

Time-lapse de imágenes de Migración neuroblasto en rodajas agudas del cerebro anterior ratón adulto

There is a substantial body of evidence indicating that new functional neurons are constitutively generated from an endogenous pool of neural stem cells ...

Automated Quantification of Synaptic Fluorescence in C. elegans

Synapse strength refers to the amplitude of postsynaptic responses to presynaptic neurotransmitter release events, and has a major impact on overall neural circuit function. Synapse strength critically depends on the abundance of neurotransmitter receptors clustered at synaptic sites on the postsynaptic membrane. Receptor levels are established developmentally, and can be altered by receptor trafficking between surface-localized, subsynaptic, and intracellular pools, representing important mechanisms of synaptic plasticity and neuromodulation. Rigorous methods to quantify synaptically-localized neurotransmitter receptor abundance are essential to study synaptic development and plasticity. Fluorescence microscopy is an optimal approach because it preserves spatial information, distinguishing synaptic from non-synaptic pools, and discriminating among receptor populations localized to different types of synapses. The genetic model organism Caenorhabditis elegans is particularly well suited for these studies due to the small size and relative simplicity of its nervous system, its transparency, and the availability of powerful genetic techniques, allowing examination of native synapses in intact animals.
Here we present a method for quantifying fluorescently-labeled synaptic neurotransmitter receptors in C. elegans. Its key feature is the automated identification and analysis of individual synapses in three dimensions in multi-plane confocal microscope output files, tabulating position, volume, fluorescence intensity, and total fluorescence for each synapse. This approach has two principal advantages over manual analysis of z-plane projections of confocal data. First, because every plane of the confocal data set is included, no data are lost through z-plane projection, typically based on pixel intensity averages or maxima. Second, identification of synapses is automated, but can be inspected by the experimenter as the data analysis proceeds, allowing fast and accurate extraction of data from large numbers of synapses. Hundreds to thousands of synapses per sample can easily be obtained, producing large data sets to maximize statistical power. Considerations for preparing C. elegans for analysis, and performing confocal imaging to minimize variability between animals within treatment groups are also discussed. Although developed to analyze C. elegans postsynaptic receptors, this method is generally useful for any type of synaptically-localized protein, or indeed, any fluorescence signal that is localized to discrete clusters, puncta, or organelles.
The procedure is performed in three steps: 1) preparation of samples, 2) confocal imaging, and 3) image analysis. Steps 1 and 2 are specific to C. elegans, while step 3 is generally applicable to any punctate fluorescence signal in confocal micrographs.

Automated Quantification of Synaptic Fluorescence in C. elegans

The abundance of neurotransmitter receptors clustered at synapses strongly influences synaptic strength. This method quantifies fluorescently-labeled neurotransmitter receptors in three dimensions with single-synapse resolution in C. elegans, allowing hundreds of synapses to be rapidly characterized within a single sample without distortions introduced by z-plane projection.

La cuantificación automática de la fluorescencia en el Synaptic<em&gt; C. elegans</em

Synapse strength refers to the amplitude of postsynaptic responses to presynaptic neurotransmitter release events, and has a major impact on overall ...

C. elegans Tracking and Behavioral Measurement

We have developed instrumentation, image processing, and data analysis techniques to quantify the locomotory behavior of C. elegans as it crawls on the surface of an agar plate. For the study of the genetic, biochemical, and neuronal basis of behavior, C. elegans is an ideal organism because it is genetically tractable, amenable to microscopy, and shows a number of complex behaviors, including taxis, learning, and social interaction1,2. Behavioral analysis based on tracking the movements of worms as they crawl on agar plates have been particularly useful in the study of sensory behavior3, locomotion4, and general mutational phenotyping5. Our system works by moving the camera and illumination system as the worms crawls on a stationary agar plate, which ensures no mechanical stimulus is transmitted to the worm. Our tracking system is easy to use and includes a semi-automatic calibration feature. A challenge of all video tracking systems is that it generates an enormous amount of data that is intrinsically high dimensional. Our image processing and data analysis programs deal with this challenge by reducing the worms shape into a set of independent components, which comprehensively reconstruct the worms behavior as a function of only 3-4 dimensions6,7. As an example of the process we show that the worm enters and exits its reversal state in a phase specific manner.

C. elegans Tracking and Behavioral Measurement

We have developed a video-rate tracking microscope system that can record and quantify C. elegans behavior at high resolution and high speeds. We have also developed computational methods to reduce the dimensionality of the worm images to a fundamental set of measurements that completely describe the shape of the worm.

C. elegans Seguimiento y Medición del Comportamiento

We have developed instrumentation, image processing, and data analysis techniques to quantify the locomotory behavior of C. elegans as it crawls on the ...

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps shape attention and also protects cells from over-stimulation. Adaptation within the olfactory circuit of C. elegans was first described by Colbert and Bargmann1,2. Here, the authors defined parameters of the olfactory adaptation paradigm, which they used to design a genetic screen to isolate mutants defective in their ability to adapt to volatile odors sensed by the Amphid Wing cells type C (AWC) sensory neurons. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor3 for 30 min they will adapt their responsiveness to the odor and will then ignore the adapting odor in a chemotaxis behavioral assay for ~1 hr. When wildtype C. elegans animals are exposed to an attractive AWC-sensed odor for ~1 hr they will then ignore the adapting odor in a chemotaxis behavioral assay for ~3 hr. These two phases of olfactory adaptation in C. elegans were described as short-term olfactory adaptation (induced after 30 min odor exposure), and long-term olfactory adaptation (induced after 60 min odor exposure). Later work from L'Etoile et al.,4 uncovered a Protein Kinase G (PKG) called EGL-4 that is required for both the short-term and long-term olfactory adaptation in AWC neurons. The EGL-4 protein contains a nuclear localization sequence that is necessary for long-term olfactory adaptation responses but dispensable for short-term olfactory adaptation responses in the AWC4. By tagging EGL-4 with a green fluorescent protein, it was possible to visualize the localization of EGL-4 in the AWC during prolonged odor exposure. Using this fully functional GFP-tagged EGL-4 (GFP::EGL-4) molecule we have been able to develop a molecular readout of long-term olfactory adaptation in the AWC5. Using this molecular readout of olfactory adaptation we have been able to perform both forward and reverse genetic screens to identify mutant animals that exhibit defective subcellular localization patterns of GFP::EGL-4 in the AWC6,7. Here we describe: 1) the construction of GFP::EGL-4 expressing animals; 2) the protocol for cultivation of animals for long-term odor-induced nuclear translocation assays; and 3) the scoring of the long-term odor-induced nuclear translocation event and recovery (re-sensitization) from the nuclear GFP::EGL-4 state.

A Molecular Readout of Long-term Olfactory Adaptation in C. elegans

Here we describe a molecular readout of long-term olfactory adaptation in Caenorhabditis elegans. The Protein Kinase G, EGL-4, is necessary for stable adaptation responses in the primary sensory neuron pair called AWC. During prolonged odor exposure EGL-4 translocates from the cytosol to nucleus of the AWC.

Una lectura molecular de adaptación a largo plazo olfativa en<em&gt; C. elegans</em

During sustained stimulation most sensory neurons will adapt their response by decreasing their sensitivity to the signal. The adaptation response helps ...

In vivo Neuronal Calcium Imaging in C. elegans

The nematode worm C. elegans is an ideal model organism for relatively simple, low cost neuronal imaging in vivo. Its small transparent body and simple, well-characterized nervous system allows identification and fluorescence imaging of any neuron within the intact animal. Simple immobilization techniques with minimal impact on the animal's physiology allow extended time-lapse imaging. The development of genetically-encoded calcium sensitive fluorophores such as cameleon 1 and GCaMP 2 allow in vivo imaging of neuronal calcium relating both cell physiology and neuronal activity. Numerous transgenic strains expressing these fluorophores in specific neurons are readily available or can be constructed using well-established techniques. Here, we describe detailed procedures for measuring calcium dynamics within a single neuron in vivo using both GCaMP and cameleon. We discuss advantages and disadvantages of both as well as various methods of sample preparation (animal immobilization) and image analysis. Finally, we present results from two experiments: 1) Using GCaMP to measure the sensory response of a specific neuron to an external electrical field and 2) Using cameleon to measure the physiological calcium response of a neuron to traumatic laser damage. Calcium imaging techniques such as these are used extensively in C. elegans and have been extended to measurements in freely moving animals, multiple neurons simultaneously and comparison across genetic backgrounds. C. elegans presents a robust and flexible system for in vivo neuronal imaging with advantages over other model systems in technical simplicity and cost.

In vivo Neuronal Calcium Imaging in C. elegans

With its small transparent body, well-documented neuroanatomy and a host of amenable genetic techniques and reagents, C. elegans makes an ideal model organism for in vivo neuronal imaging using relatively simple, low-cost techniques. Here we describe single neuron imaging within intact adult animals using genetically encoded fluorescent calcium indicators.

Formación de imágenes in vivo de calcio neuronal en C. elegans

The nematode worm C. elegans is an ideal model organism  for relatively simple, low cost neuronal imaging in vivo. Its small transparent body and simple, ...

Nucleofection of Rodent Neuroblasts to Study Neuroblast Migration In vitro

The subventricular zone (SVZ) located in the lateral wall of the lateral ventricles plays a fundamental role in adult neurogenesis. In this restricted area of the brain, neural stem cells proliferate and constantly generate neuroblasts that migrate tangentially in chains along the rostral migratory stream (RMS) to reach the olfactory bulb (OB). Once in the OB, neuroblasts switch to radial migration and then differentiate into mature neurons able to incorporate into the preexisting neuronal network. Proper neuroblast migration is a fundamental step in neurogenesis, ensuring the correct functional maturation of newborn neurons. Given the ability of SVZ-derived neuroblasts to target injured areas in the brain, investigating the intracellular mechanisms underlying their motility will not only enhance the understanding of neurogenesis but may also promote the development of neuroregenerative strategies.
This manuscript describes a detailed protocol for the transfection of primary rodent RMS postnatal neuroblasts and the analysis of their motility using a 3D in vitro migration assay recapitulating their mode of migration observed in vivo. Both rat and mouse neuroblasts can be quickly and efficiently transfected via nucleofection with either plasmid DNA, small hairpin (sh)RNA or short interfering (si)RNA oligos targeting genes of interest. To analyze migration, nucleofected cells are reaggregated in &#39;hanging drops&#39; and subsequently embedded in a three-dimensional matrix. Nucleofection per se does not significantly impair the migration of neuroblasts. Pharmacological treatment of nucleofected and reaggregated neuroblasts can also be performed to study the role of signaling pathways involved in neuroblast migration.

Nucleofection of Rodent Neuroblasts to Study Neuroblast Migration In vitro

Neuroblast migration is a crucial step in postnatal neurogenesis. The protocol described here can be used to investigate the role of candidate regulators of neuroblast migration by employing DNA/small hairpin RNA (shRNA) nucleofection and a 3D migration assay with neuroblasts isolated from the rodent postnatal rostral migratory stream.

Nucleofection de roedores neuroblastos para el Estudio de la Migración Neuroblast<em&gt; In vitro</em

The subventricular zone (SVZ) located in the lateral wall of the lateral ventricles plays a fundamental role in adult neurogenesis. In this restricted ...

In Vivo Imaging of Dauer-specific Neuronal Remodeling in C. elegans

The mechanisms controlling stress-induced phenotypic plasticity in animals are frequently complex and difficult to study in vivo. A classic example of stress-induced plasticity is the dauer stage of C. elegans. Dauers are an alternative developmental larval stage formed under conditions of low concentrations of bacterial food and high concentrations of a dauer pheromone. Dauers display extensive developmental and behavioral plasticity. For example, a set of four inner-labial quadrant (IL2Q) neurons undergo extensive reversible remodeling during dauer formation. Utilizing the well-known environmental pathways regulating dauer entry, a previously established method for the production of crude dauer pheromone from large-scale liquid nematode cultures is demonstrated. With this method, a concentration of 50,000 - 75,000 nematodes/ml of liquid culture is sufficient to produce a highly potent crude dauer pheromone. The crude pheromone potency is determined by a dose-response bioassay. Finally, the methods used for in vivo time-lapse imaging of the IL2Qs during dauer formation are described.

In Vivo Imaging of Dauer-specific Neuronal Remodeling in C. elegans

Following exposure to specific environmental stressors, the nematode Caenorhabditis elegans undergoes extensive phenotypic plasticity to enter into a stress-resistant &#8216;dauer&#8217; juvenile stage. We present methods for the controlled induction and imaging of neuroplasticity during dauer.

En vivo de imágenes de Dauer-específica neuronal Remodelación en C. elegans

The mechanisms controlling stress-induced phenotypic plasticity in animals are frequently complex and difficult to study in vivo. A classic example of ...