We would like to acknowledge David O'Brien for his support with data analysis, and all the members of the Canto-Soler lab for their critical discussions. This work was supported by NIH grants EY004859 and EY022631 (MVCS), Core Grant EY1765, and an unrestricted departmental grant from Research to Prevent Blindness, Inc.

Todos los procedimientos descritos en este trabajo se realizaron de acuerdo a las pautas recomendadas por el Cuidado de Animales y el empleo Comisión de la Universidad Johns Hopkins. 1. Antes de Tiempo: Preparación de Instrumentos, reactivos y Platos <ol><li> Preparación de los huevos: Incubar huevos de gallina fertilizados White Leghorn a 37,5 ° C y una humedad relativa del 60% durante 5 días en una incubadora de huevos. NOTA: Una incubadora con balanceo de la capacidad puede ser útil para la normalización y la sincronización de desarrollo embrionario, pero oscilante no es estrictamente necesario para el resultado de este protocolo. </li><li> Preparación de plásmido: <ol><li> Diseño plásmido constructo para la sobreexpresión de genes o regulación a la baja (por ejemplo, mediante el uso de la tecnología del RNAi 1,34) según sea necesario. Incluya un gen indicador (por ejemplo, EGFP, RFP o LacZ) en la construcción siempre que sea posible. NOTA: Algunos promotores de uso común, tales como el CMV, pueden llegar a ser silenciada en el tiempo. El promot CAGer (pollo beta-actina promotor con promotor de CMV) es una muy buena alternativa, proporcionando eficiente expresión a largo plazo del gen de interés 35-37. </li><li> Preparar una solución de plásmido a una concentración de 1,5 g / l en PBS estéril. OPCIONAL: Preparar la solución plásmido antes de tiempo y almacenarlo congelado hasta que esté listo para su uso. NOTA: Superior concentraciones de plásmido no dan lugar a un aumento significativo en la eficiencia, mientras que el uso de concentraciones más bajas de plásmidos disminuyen la eficiencia de transfección 1. </li></ol></li><li> Electrodos: <ol><li> Para el uso de ánodos de oro gruesa punta del electrodo (véase la Tabla de Materiales Específicos / Equipo). Limpie con etanol al 70%. NOTA: Aislamiento del oro punta de electrodo, dejando aproximadamente 0,5 mm expuestos, es aconsejable minimizar la fuga de la corriente eléctrica. Información para material aislante se puede encontrar en la Tabla de materiales específicos. </li><li> Hacer un cátodo de un cuadrado de 2,5 mm bfilamento de buey, de 4,5 mm de ancho (normalmente utilizado en extractores micropipeta). Con la ayuda de unas pinzas, deshacer la caja cuadrada y enderezar filamento en una tira larga. Luego, bajo microscopio de disección y usando una regla como guía, doblar el filamento en una forma cuadrada &#39;U&#39; 3 mm de largo en la base y 2 mm de alto en un lado, con el otro lado de la longitud restante del filamento (Figura 1 , C - D). Con unas pinzas, sumerja el electrodo en etanol al 96% y la llama para esterilizar. A continuación, conecte un cable eléctrico con una pequeña pinza de conexión para el brazo del electrodo más largo. </li></ol></li><li> Cámara electroporación de configuración: <ol><li> Preparar la cámara de electroporación mediante la reducción de la tapa de un tubo de microcentrífuga de 1,5 ml estéril y la colocación de ella, lado plano hacia abajo, a una placa de Petri de 100 mm usando cinta (Figura 1E). NOTA: Otros recipiente en forma de un pozo de tamaño similar funcionaría; sin embargo, un tubo de microcentrífuga de tapa es fácilmente accesible y autoclavable. El biendebe ser lo suficientemente para alojar un electrodo de ojo de pollo y el cátodo grande, pero no tan grande como para resultar en una pérdida de solución de plásmido. </li></ol></li></ol> 2. Ex Procedimiento electroporación in ovo <ol><li> Preparación de los instrumentos: <ol><li> Esterilizar las herramientas de micro-disección (2 pares de grandes pinzas Moloney curvos para la apertura de las cáscaras de huevo y sacando embriones, 2 pares de punta fina curvas pinzas Dumont para la eliminación de RPE, un par de Bonn dentado pinzas para quitar la lente y vítreo) por inmersión de la consejos en etanol al 96% y en llamas. Alcance la disección Limpie con trapos mojados en etanol al 70%. Calentar una botella de solución salina equilibrada estéril calcio-magnesio-libre de Hank (CMF-HBSS) en un baño de agua a 37 ° C. Rellene 100 mm placas de Petri estériles a 3/4 de su capacidad con una cálida CMF-HBSS. </li><li> Coloque la cámara de electroporación bajo otro microscopio de disección limpia y llena con 120 l de solución de plásmido. Conectar los electrodos al aparato de electroporación, haciendoSeguro electrodo de medida está conectado al polo negativo y el oro con punta de electrodo al polo positivo. </li></ol></li><li> Embrión Colección: <ol><li> Limpie los huevos limpiando conchas con toallitas húmedas en etanol al 70%. Mantener procedimiento estéril durante todo el resto del protocolo para evitar llevar la contaminación en los cultivos. El uso de grandes pinzas Moloney curvas abrir cuidadosamente un agujero en la cáscara del huevo golpeando suavemente en la punta redondeada de un huevo (más de la cámara de aire) y luego agarre y sacando trozos de concha. </li><li> Con otro par de pinzas quitar las membranas y recoger embriones por sacar con pala fuera del huevo (con cuidado de no dañar el embrión). Colóquelo en un plato con CMF-HBSS. NOTA: Recoger la mayor cantidad embriones como sea necesario para obtener el número deseado de vasos de la retina para la electroporación como se especifica en 2.4.4 </li><li> PASO CRÍTICO: Etapa de los embriones de acuerdo a Hamburger y Hamilton 38. NOTA: Para obtener embriones óptimos de eficienciadebe ser en la etapa 27 (Figura 2A). </li><li> La eutanasia a los embriones por decapitación utilizando fórceps Moloney. </li></ol></li><li> La obtención de Copas de la retina: <ol><li> Usando pinzas Dumont finas, enuclear cuidado de los ojos y la transferencia a un nuevo plato CMF-HBSS. </li><li> A partir de la parte posterior de cada ojo, cerca de la cabeza del nervio óptico y utilizando dos pinzas Dumont finas, introducir un consejo de cada par de pinzas entre la retina neural y RPE y cuidadosamente diseccionar el EPR ser cauteloso para no dañar el neuronal retina (Figura 2B). NOTA: La falta de Ca 2+ y Mg 2+ en la solución ayudará a la RPE desprenda de la retina neural más fácilmente. </li></ol></li><li> Electroporación: <ol><li> Establecer parámetros de electroporador para entregar 5 pulsos cuadrados de 15 voltios, 50 mseg de duración y 950 intervalo de milisegundos. Place &#39;U&#39; en forma de electrodo negativo dentro de la cámara de electroporación (microcentrífuga tapa de llenadoed con 120 l de solución que contiene el plásmido). </li><li> Usando pinzas Dumont curvas transferir una taza de la retina a la cámara de electroporación (por sacar con pala, no presionar), y lo colocan en el interior del electrodo en forma de &#39;U&#39;, con la parte posterior de la retina hacia la parte inferior del electrodo y la lente hacia arriba ( Figura 2D). </li><li> Coloque el ánodo de modo que toque la parte anterior del ojo, al lado de la lente, y el uso de pedal de pie del electroporador entregar los pulsos eléctricos. </li><li> Transferencia de la taza de la retina a electroporación a una nueva placa de Petri con CMF-HBSS y repita el procedimiento de electroporación con cada uno de los vasos de la retina restantes. NOTA: Hasta 6 tazas de la retina puede ser a electroporación con la misma solución plásmido sin una disminución significativa en la eficiencia de la transfección. </li><li> Retire el objetivo y el cuerpo vítreo de cada vaso de la retina a electroporación sujetando con pinzas dentadas de Bonn y tirando suavemente a través de tque por alumno apertura mientras mantiene el ojo en su lugar con el dorso de las pinzas Dumont curvas. </li><li> Proceder a la disociación y la cultura de las células de la retina electroporación siguientes procedimientos estándar. NOTA: Para un protocolo detallado en la disociación y la cultura de células de la retina de pollo se refieren a Vergara y Canto-Soler, 2012, la disposición 4 21 En este protocolo, las células se sembraron a baja densidad en placas de 6 pocillos polyornithine recubiertos o 35. platos -mm (6 x 10 5 células / 35 mm de diámetro, así o plato). El medio utilizado es medio 199 con penicilina / glutamina, 10% de suero de ternera fetal (FCS), y ácido linoleico-BSA a 100 mg / ml. Los cultivos se mantienen en un humidificado 37 ° C incubadora con 5% de CO 2. Usando este procedimiento, 5 - 6 x 10 6 células típicamente se pueden obtener por cada etapa 27 del ojo a electroporación. NOTA: Idealmente, no más de 3 horas debe pasar entre recogida de embriones y de las planchas de células, para garantizar una buena supervivencia celulary minimizar el estrés. Un tiempo típico para la observación y el análisis adicional es después de 4 días de cultivo, ya que en este punto que las células han logrado una buena diferenciación morfológica y molecular y la supervivencia sigue siendo alta. </li></ol></li></ol>

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M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+hybrid+promoter-containing+vector+for+direct+cloning+and+enhanced+expression+of+PCR-amplified+ORFs+in+mammalian+cells.">A hybrid promoter-containing vector for direct cloning and enhanced expression of PCR-amplified ORFs in mammalian cells.</a> Mol Biol Rep. 37 (6), 2757-2765 (2009).</li><li>Hamburger, V., Hamilton, H. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+series+of+normal+stages+in+the+development+of+the+chick+embryo.">A series of normal stages in the development of the chick embryo.</a> Dev Dyn. 195 (4), 231-272 (1992).</li></ol>

The authors declare that they have no competing financial interests or other conflicts of interest.

El paso más crítico para el éxito de este protocolo es la selección de la etapa apropiada de los embriones. En publicaciones anteriores, se da una serie de etapas embrionarias de estas culturas, por lo general definido por los días del día de incubación o embrionarias (ED); por lo que se suele suponer que el uso de ED 5 de ED 6 embriones producirá resultados equivalentes. Sin embargo, hemos encontrado que en el escenario 27 (ED 5), la eficiencia de transfección será de alrededor de 22% de la población total d...

Cultivos de células disociadas de retinas de embriones de pollo se han utilizado ampliamente para estudiar diversos aspectos de la biología de las células fotorreceptoras, incluyendo su supervivencia 2-9 diferenciación 10-12, el crecimiento de neuritas 13, y más. Las ventajas de este sistema, desarrollado en la década de 1980 por Rubén Adler y colaboradores y perfeccionadas por él y para otros grupos de 14-20, residen en las características intrínsecas de la chica como un modelo animal 21. El gran tamaño del ojo polluelo, incluso en las etapas embrionarias, proporciona grandes cantidades de material para cultivos. Por otra parte, cuando los cultivos se realizan con el día embrionario (ED) 5 - 6 retinas, el 55 - 80% de sus células progenitoras diferenciar como fotorreceptores 14,15,18,22,23, y desde aproximadamente el 86% de los fotorreceptores en este animal son conos 24, estas culturas son especialmente adecuados para estudios centrados en este tipo de células. Recientemente hemos desaped y caracterizado una técnica sencilla que permite una alta eficiencia plásmido transfección de las células en estos cultivos, ampliando así la utilidad de este sistema, facilitando estudios missexpression genética 1. El desarrollo de esta técnica se deriva de un vacío en la literatura científica de métodos que proporcionen un nivel aceptable de la transfección para permitir el estudio de la función génica en una célula de manera autónoma. Esto es en parte debido a cultivos neuronales primarios son notoriamente difíciles de transfectar 25,26. Algunas de las técnicas más comúnmente utilizadas previamente disponibles para este propósito incluyen métodos de transfección químicos tales como lipofección o calcio transfección mediada por fosfato, que se traducen en una mayor eficacia en el orden de 3-5% y puede ejercer una toxicidad considerable, 27-32. A pesar de que el uso de plásmidos con un sistema reportero enzimática puede eludir el problema de la pobre eficiencia de la transfección mediante la amplificación de la señal, no lo hacendiscriminar los efectos específicos de la célula, y sus resultados se basan en una población de células pequeñas que pueden no ser representativos del conjunto. Otro método ampliamente utilizado en el pollo, infección por el virus RCAS, sólo es aplicable a las células en proliferación y por lo tanto no es adecuado para este sistema de cultivo primario de la retina 33. En el protocolo actual ojos de embriones de pollo se enucleados en la etapa 27 (ED 5), se retira el epitelio pigmentado de la retina (RPE), y la copa de la retina se coloca en una cámara de electroporación llena con una solución que contiene el plásmido y electroporación utilizando a medida electrodos, seguido por la disociación de la retina y de cultivo utilizando técnicas estándar 21. Después de la optimización de este procedimiento hemos sido capaces de alcanzar consistentemente las eficacias de transfección en el orden del 22% del número total de células en cultivo y 25% dentro de la población de los fotorreceptores solo, sin comprometer las características de supervivencia y diferenciación de lasculturas 1. Aquí proporcionamos un protocolo detallado que describa todos los pasos importantes de este procedimiento a fin de garantizar el éxito y la reproducibilidad de esta técnica.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>ECM 830 Electro Square Porator</td>
			<td>BTX/ Harvard Apparatus</td>
			<td>45-0052</td>
			<td></td>
		</tr>
		<tr>
			<td>Genetrode, L-Shaped, 5 mm Gold Tip</td>
			<td>BTX/ Harvard Apparatus</td>
			<td>45-0115 model 512</td>
			<td>Gold tipped electrode used as anode</td>
		</tr>
		<tr>
			<td>Polyimide Tubing</td>
			<td>Vention Medical</td>
			<td>custom made</td>
			<td>Internal Diameter: 0.5mm / wall thickness: 0.15-0.2mm. Used for insulating gold tiped electrode</td>
		</tr>
		<tr>
			<td>2.5mm square box filament, 4.5mm wide</td>
			<td>Sutter Instrument Company</td>
			<td>FB245B</td>
			<td>Used to make cathode electrode</td>
		</tr>
		<tr>
			<td>HBSS, no calcium, no magnesium, no phenol red</td>
			<td>Gibco - Life Technologies</td>
			<td>14175-095</td>
			<td></td>
		</tr>
		<tr>
			<td>Moloney forceps</td>
			<td>Roboz</td>
			<td>RS-8254</td>
			<td>Serrated; Slight Curve; 4.5&#34; Length</td>
		</tr>
		<tr>
			<td>Dumont tweezers 5/45</td>
			<td>Roboz</td>
			<td>RS-5058</td>
			<td>Pattern #5, 45 Degree Angle; .10 X .06mm Tip Size; 109mm Length</td>
		</tr>
		<tr>
			<td>Bonn micro forceps, 1x2 teeth</td>
			<td>Roboz</td>
			<td>RS-5172</td>
			<td>Tying Platform; 1X2 Teeth, 0.12mm Teeth; 3.75&#34; Length; .3mm Tip Width</td>
		</tr>
	</tbody>
</table>

efficient gene transfer in chick retinas for primary cell culture studies: an ex-ovo electroporation approach

Los cultivos de fotorreceptores enriquecido cono derivados de las retinas de embriones de pollo se han convertido en una herramienta indispensable para los investigadores de todo el mundo que estudian la biología de las neuronas de la retina, en particular los fotorreceptores. Las aplicaciones de este sistema van más allá de la investigación básica, ya que se pueden adaptar fácilmente a las tecnologías de alto rendimiento para el desarrollo de fármacos. Sin embargo, la manipulación genética de fotorreceptores de la retina en estos cultivos ha demostrado ser muy difícil, que presenta una importante limitación a la utilidad del sistema. Recientemente hemos desarrollado y validado un ex ovo técnica de electroporación plásmido que aumenta la tasa de transfección de células de la retina en estos cultivos por cinco veces en comparación con otros protocolos disponibles en la actualidad 1. En este método los ojos de embriones de pollo se enucleados en la etapa 27, se retira el RPE, y la copa de la retina se coloca en una solución que contiene el plásmido y se electroporó usando Custom- de fácil construcciónelectrodos hechos. Las retinas son entonces disocian y se cultivan utilizando procedimientos estándar. Esta técnica se puede aplicar a los estudios de sobreexpresión, así como a la regulación a la baja de la expresión génica, por ejemplo, mediante el uso de la tecnología del RNAi plásmido impulsado, comúnmente la consecución de la expresión del transgén en 25% de la población de los fotorreceptores. El formato de vídeo de la presente publicación hará que esta tecnología de fácil acceso para los investigadores en el campo, lo que permite el estudio de la función de genes en cultivos de retina primarios. También hemos incluido una explicación detallada de los pasos críticos de este procedimiento para un resultado exitoso y reproducibilidad.

Aquí presentamos un protocolo sencillo para el plásmido transfección en vasos de la retina de pollo enucleados para el cultivo celular disociada subsiguiente. La transfección se consigue mediante electroporación utilizando fácil de hacer electrodos personalizados (Figuras 1 - 2). Los parámetros descritos en este protocolo se han optimizado para obtener eficiencias de transfección que oscilan entre el 20 y el 27% (con un promedio de 22%) (Figura 3D). Tenga en cue...

Watch this Scientific Journal Video about Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach at JoVE.com

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

Cultivos de células de la retina de embriones de pollo constituyen herramientas valiosas para el estudio de la biología de los fotorreceptores. Hemos desarrollado una técnica de transferencia de genes eficiente, basado en ex ovo plásmido electroporación de las retinas antes del cultivo. Esta técnica aumenta considerablemente la eficiencia de transfección a través de protocolos disponibles en la actualidad, lo que hace posible la manipulación genética para este sistema.

Transferencia génica eficaz en polluelo retinas para estudios de cultivo celular primario: Un<em&gt; Ex-ovo</em&gt; Enfoque electroporación

The cone photoreceptor-enriched cultures derived from embryonic chick retinas have become an indispensable tool for researchers around the world studying ...

efficient-gene-transfer-chick-retinas-for-primary-cell-culture

Research

JoVE Journal

Developmental Biology

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

8.1K vistas.  The Johns Hopkins University School of Medicine.  Cultivos de células de la retina de embriones de pollo constituyen herramientas valiosas para el estudio de la biología de los fotorreceptores. Hemos desarrollado una técnica de transferencia de genes eficiente, basado en ex ovo plásmido electroporación de las retinas antes del cultivo. Esta técnica aumenta considerablemente la eficiencia de transfección a través de protocolos disponibles en la actualidad, lo que hace posible la manipulación genética p...

Video: Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

Optimized Ex-ovo Culturing of Chick Embryos to Advanced Stages of Development

Research in anatomy, embryology, and developmental biology has largely relied on the use of model organisms. In order to study development in live embryos model organisms, such as the chicken, are often used. The chicken is an excellent model organism due to its low cost and minimal maintenance, however they present observational challenges because they are enclosed in an opaque eggshell. In order to properly view the embryo as it develops, the shell must be windowed or removed. Both windowing and ex ovo techniques have been developed to assist researchers in the study of embryonic development. However, each of the methods has limitations and challenges. Here, we present a simple, optimized ex ovo culture technique for chicken embryos that enables the observation of embryonic development from stage HH 19 into late stages of development (HH 40), when many organs have developed. This technique is easy to adopt in both undergraduate classes and more advanced research laboratories where embryo manipulations are conducted.

Optimized Ex-ovo Culturing of Chick Embryos to Advanced Stages of Development

Viewing and accessing the chicken embryo during development can be challenging. We have developed an ex ovo method that is simple, cost effective, and can easily be used in a classroom or research setting. This method provides access to the embryo into late stages of embryonic development (HH 40).

Optimizado<em&gt; Ex-ovo</em&gt; El cultivo de embriones del polluelo a etapas avanzadas de desarrollo

Research in anatomy, embryology, and developmental biology has largely relied on the use of model organisms. In order to study development in live embryos ...

Investigación

Biología del Desarrollo

Culture of Embryonic Mouse Cochlear Explants and Gene Transfer by Electroporation

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair cells are aligned in one row of inner hair cells and three rows of outer hair cells that extend along the basal to apical axis of the cochlea. The explant culture technique described here provides an efficient method to isolate and maintain cochlear explants from the embryonic mouse inner ear. Also, the morphology and molecular characteristics of sensory hair cells and nonsensory supporting cells within the cochlear explant cultures resemble those observed in vivo and can be studied within its intrinsic cellular environment. The cochlear explants can serve as important experimental tools for the identification and characterization of molecular and genetic pathways that are involved in cellular specification and patterning. Although transgenic mouse models provide an effective approach for gene expression studies, a considerable number of mouse mutants die during embryonic development thereby hindering the analysis and interpretation of developmental phenotypes. The organ of Corti from mutant mice that die before birth can be cultured so that their in vitro development and responses to different factors can be analyzed. Additionally, we describe a technique for electroporating embryonic cochlear explants ex vivo which can be used to downregulate or overexpress specific gene(s) and analyze their potential endogenous function and test whether specific gene product is necessary or sufficient in a given context to influence mammalian cochlear development1-8.

We present a method that describes isolation and culture of cochlear explants from embryonic mouse inner ear. We also demonstrate a method for gene transfer into cochlear explants via square-wave electroporation. The in vitro explant culture coupled with gene transfer technique enables researchers to study the effects of altering gene expression during development.

Cultura de embriones de ratón explantes cocleares y Gene Transfer por electroporación

Auditory hair cells located within the mouse organ of Corti detect and transmit sound information to the central nervous system. The mechanosensory hair ...

An Optogenetic Approach for Assessing Formation of Neuronal Connections in a Co-culture System

Here we describe a protocol to generate a co-culture consisting of 2 different neuronal populations. Induced pluripotent stem cells (iPSCs) are reprogrammed from human fibroblasts using episomal vectors. Colonies of iPSCs can be observed 30 days after initiation of fibroblast reprogramming. Pluripotent colonies are manually picked and grown in neural induction medium to permit differentiation into neural progenitor cells (NPCs). iPSCs rapidly convert into neuroepithelial cells within 1 week and retain the capability to self-renew when maintained at a high culture density. Primary mouse NPCs are differentiated into astrocytes by exposure to a serum-containing medium for 7 days and form a monolayer upon which embryonic day 18 (E18) rat cortical neurons (transfected with channelrhodopsin-2 (ChR2)) are added. Human NPCs tagged with the fluorescent protein, tandem dimer Tomato (tdTomato), are then seeded onto the astrocyte/cortical neuron culture the following day and allowed to differentiate for 28 to 35 days. We demonstrate that this system forms synaptic connections between iPSC-derived neurons and cortical neurons, evident from an increase in the frequency of synaptic currents upon photostimulation of the cortical neurons. This co-culture system provides a novel platform for evaluating the ability of iPSC-derived neurons to create synaptic connections with other neuronal populations.

A protocol to generate a co-culture system consisting of neurons derived from induced pluripotent stem cells (iPSCs), primary cortical neurons and astrocytes is described. This co-culture system allows detection of the formation of synaptic contacts and circuits between new, iPSC-derived neurons and pre-existing cortical neurons expressing channelrhodopsin-2.

Un enfoque optogenética para Evaluar formación de conexiones neuronales en un sistema de co-cultura

Here we describe a protocol to generate a co-culture consisting of 2 different neuronal populations. Induced pluripotent stem cells (iPSCs) are ...

Forward Genetic Approach to Uncover Stress Resistance Genes in Mice &#8212; A High-throughput Screen in ES Cells

Phenotype-driven genetic screens in mice is a powerful technique to uncover gene functions, but are often hampered by extremely high costs, which severely limits its potential. We describe here the use of mouse embryonic stem (ES) cells as surrogate cells to screen for a phenotype of interest and subsequently introduce these cells into a host embryo to develop into a living mouse carrying the phenotype. This method provides (1) a cost effective, high-throughput platform for genetic screen in mammalian cells; (2) a rapid way to identify the mutated genes and verify causality; and (3) a short-cut to develop mouse mutants directly from these selected ES cells for whole animal studies. We demonstrated the use of paraquat (PQ) to select resistant mutants and identify mutations that confer oxidative stress resistance. Other stressors or cytotoxic compounds may also be used to screen for resistant mutants to uncover novel genetic determinants of a variety of cellular stress resistance.

Stress resistance is one of the hallmarks for longevity and is known to be genetically governed. Here, we developed an unbiased high-throughput method to screen for mutations that confer stress resistance in ES cells with which to develop mouse models for longevity studies.

Enfoque genético adelante para descubrir Estrés Los genes de resistencia en ratones - Una pantalla de alto rendimiento en células madre embrionarias

Phenotype-driven genetic screens in mice is a powerful technique to uncover gene functions, but are often hampered by extremely high costs, which severely ...

Ex Vivo Culture of Chick Cerebellar Slices and Spatially Targeted Electroporation of Granule Cell Precursors

The cerebellar external granule layer (EGL) is the site of the largest transit amplification in the developing brain, and an excellent model for studying neuronal proliferation and differentiation. In addition, evolutionary modifications of its proliferative capability have been responsible for the dramatic expansion of cerebellar size in the amniotes, making the cerebellum an excellent model for evo-devo studies of the vertebrate brain. The constituent cells of the EGL, cerebellar granule progenitors, also represent a significant cell of origin for medulloblastoma, the most prevalent paediatric neuronal tumour. Following transit amplification, granule precursors migrate radially into the internal granular layer of the cerebellum where they represent the largest neuronal population in the mature mammalian brain. In chick, the peak of EGL proliferation occurs towards the end of the second week of gestation. In order to target genetic modification to this layer at the peak of proliferation, we have developed a method for genetic manipulation through ex vivo electroporation of cerebellum slices from embryonic Day 14 chick embryos. This method recapitulates several important aspects of in vivo granule neuron development and will be useful in generating a thorough understanding of cerebellar granule cell proliferation and differentiation, and thus of cerebellum development, evolution and disease.

Ex Vivo Culture of Chick Cerebellar Slices and Spatially Targeted Electroporation of Granule Cell Precursors

The cerebellar external granule layer is the site of the largest transit amplification in the developing brain. Here, we present a protocol to target genetic modification to this layer at the peak of proliferation using ex vivo electroporation and culture of cerebellar slices from embryonic Day 14 chick embryos.

Ex Vivo Cultura de polluelo cerebelosos Rebanadas y espacialmente focalizadas Electroporación de gránulos precursores celulares

The cerebellar external granule layer (EGL) is the site of the largest transit amplification in the developing brain, and an excellent model for studying ...

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2&#180;-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr&#160;after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

The auditory organ mediates hearing. Here we present a modified in ovo micro-electroporation method optimized for studying auditory progenitor cell proliferation and differentiation in the developing chicken auditory organ.

La transferencia de genes en el pollo auditiva de órgano de<em&gt; En Ovo</em&gt; Micro-electroporación

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. ...

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and molecular level. To alter intracardiac hemodynamics, fertilized chicken eggs are incubated in a humidified chamber to obtain embryos of the desired stage (HH17). Once this developmental stage is achieved, the embryo is maintained ex ovo and hemodynamics in the embryonic heart are altered by partially constricting the outflow tract (OFT) with a surgical suture at the junction of the OFT and ventricle (OVJ). Control embryos are also cultured ex ovo but are not subjected to the surgical intervention. Banded and control embryos are then incubated in a humidified incubator for the desired period of time, after which 2D ultrasound is employed to analyze the change in blood flow velocity at the OVJ as a result of OFT banding. Once embryos are maintained ex ovo, it is important to ensure adequate hydration in the incubation chamber so as to prevent drying and eventually embryo death. Using this new banded model, it is now possible to perform analyses of changes in the expression of key players involved in valve development and to understand the role of hemodynamics on cellular responses in vivo, which could not be achieved previously.

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

For the first time we present here a reproducible banding procedure to alter hemodynamics in the developing heart ex ovo. This is achieved by partially constricting the outflow tract (OFT).

Una novela<em&gt; Ex Ovo</em&gt; Banda Técnica para alterar intracardiaca Hemodinámica en un sistema embrionario de pollo

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and ...

An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery

Epithelial to mesenchymal transition (EMT) describes the process of epithelium transdifferentiating into mesenchyme. EMT is a fundamental process during embryonic development that also commonly occurs in glioblastoma, the most frequent malignant brain tumor. EMT has also been observed in multiple carcinomas outside the brain including breast cancer, lung cancer, colon cancer, gastric cancer. EMT is centrally linked to malignancy by promoting migration, invasion and metastasis formation. The mechanisms of EMT induction are not fully understood. Here we describe an in vitro system for standardized isolation of cortical neural stem cells (NSCs) and subsequent EMT-induction. This system provides the flexibility to use either single cells or explant culture. In this system, rat or mouse embryonic forebrain NSCs are cultured in a defined medium, devoid of serum and enzymes. The NSCs expressed Olig2 and Sox10, two transcription factors observed in oligodendrocyte precursor cells (OPCs). Using this system, interactions between FGF-, BMP- and TGF&#946;-signaling involving Zeb1, Zeb2, and Twist2 were observed where TGF&#946;-activation significantly enhanced cell migration, suggesting a synergistic BMP-/TGF&#946;-interaction. The results point to a network of FGF-, BMP- and TGF&#946;-signaling to be involved in EMT induction and maintenance. This model system is relevant to investigate EMT in vitro. It is cost-efficient and shows high reproducibility. It also allows for the comparison of different compounds with respect to their migration responses (quantitative distance measurement), and high-throughput screening of compounds to inhibit or enhance EMT (qualitative measurement). The model is therefore well suited to test drug libraries for substances affecting EMT.

Epithelial to mesenchymal transition (EMT) allows cancers to become invasive. To investigate EMT, a neural stem cell (NSC)-based in vitro model devoid of serum and enzymes is described. This standardized system allows quantitative and qualitative assessment of cell migration, gene and protein expression. The model is suited for drug discovery.

Un modelo enzima y Cultura Neural Stem Cell libre de suero para la EMT Investigación Adecuado para el descubrimiento de fármacos

Epithelial to mesenchymal transition (EMT) describes the process of epithelium transdifferentiating into mesenchyme. EMT is a fundamental process during ...

A Submerged Filter Paper Sandwich for Long-term Ex Ovo Time-lapse Imaging of Early Chick Embryos

Due to its availability, low cost, flat geometry, and transparency, the ex ovo chick embryo has become a major vertebrate animal model for the study of morphogenetic events, such as gastrulation2, neurulation3-5, somitogenesis6, heart bending7,8, and brain formation9-13, during early embryogenesis. Key to understanding morphogenetic processes is to follow them dynamically by time-lapse imaging. The acquisition of time-lapse movies of chick embryogenesis ex ovo has been limited either to short time windows or to the need for an incubator to control temperature and humidity around the embryo14. Here, we present a new technique to culture chick embryos ex ovo for high-resolution time-lapse imaging using transmitted light microscopy. The submerged filter paper sandwich is a variant of the well-established filter paper carrier technique (EC-culture)1 and allows for the culturing of chick embryos without the need for a climate chamber. The embryo is sandwiched between two identical filter paper carriers and is kept fully submerged in a simple, temperature-controlled medium covered by a layer of light mineral oil. Starting from the primitive streak stage (Hamburger-Hamilton stage 5, HH5)15 up to at least the 28-somite stage (HH16)15, embryos can be cultured with either their ventral or dorsal side up. This allows the acquisition of time-lapse movies covering about 30 hr of embryonic development. Representative time-lapse frames and movies are shown. Embryos are compared morphologically to an embryo cultured in the standard EC-culture.
The submerged filter paper sandwich provides a stable environment to study early dorsal and ventral morphogenetic processes. It also allows for live fluorescence imaging and micromanipulations, such as microsurgery, bead implantation, microinjection, gene silencing, and electroporation, and has a strong potential to be combined with immersion objectives for laser-based imaging (including light-sheet microscopy).

A Submerged Filter Paper Sandwich for Long-term Ex Ovo Time-lapse Imaging of Early Chick Embryos

Here, we present a new technique to culture chick embryos ex ovo for time-lapse imaging using transmitted light and fluorescence microscopy. The submerged filter paper sandwich is a variant of the well-established filter paper carrier technique1 that allows for the culturing of chick embryos fully-submerged in a liquid culture medium.

Un filtro de papel sumergido Sandwich para el largo plazo<em&gt; Ex Ovo</em&gt; Time-lapse de pollo temprano embriones

Due to its availability, low cost, flat geometry, and transparency, the ex ovo chick embryo has become a major vertebrate animal model for the study of ...

CRISPR-mediated Loss of Function Analysis in Cerebellar Granule Cells Using In Utero Electroporation-based Gene Transfer

Brain malformation is often caused by genetic mutations. Deciphering the mutations in patient-derived tissues has identified potential causative factors of the diseases. To validate the contribution of a dysfunction of the mutated genes to disease development, the generation of animal models carrying the mutations is one obvious approach. While germline genetically engineered mouse models (GEMMs) are popular biological tools and exhibit reproducible results, it is restricted by time and costs. Meanwhile, non-germline GEMMs often enable exploring gene function in a more feasible manner. Since some brain diseases (e.g., brain tumors) appear to result from somatic but not germline mutations, non-germline chimeric mouse models, in which normal and abnormal cells coexist, could be helpful for disease-relevant analysis. In this study, we report a method for the induction of CRISPR-mediated somatic mutations in the cerebellum. Specifically, we utilized conditional knock-in mice, in which Cas9 and GFP are chronically activated by the CAG (CMV enhancer/chicken &#223;-actin) promoter after Cre-mediated recombination of the genome. The self-designed single-guide RNAs (sgRNAs) and the Cre recombinase sequence, both encoded in a single plasmid construct, were delivered into cerebellar stem/progenitor cells at an embryonic stage using in utero electroporation. Consequently, transfected cells and their daughter cells were labeled with green fluorescent protein (GFP), thus facilitating further phenotypic analyses. Hence, this method is not only showing electroporation-based gene delivery into embryonic cerebellar cells but also proposing a novel quantitative approach to assess CRISPR-mediated loss-of-function phenotypes.

CRISPR-mediated Loss of Function Analysis in Cerebellar Granule Cells Using In Utero Electroporation-based Gene Transfer

Conventional loss-of-function studies of genes using knockout animals have often been costly and time-consuming. Electroporation-based CRISPR-mediated somatic mutagenesis is a powerful tool to understand gene functions in vivo. Here, we report a method to analyze knockout phenotypes in proliferating cells of the cerebellum.

Mediada por CRISPR pérdida de función análisis en gránulo cerebeloso células usando en el útero electroporación basado en la transferencia de genes

Brain malformation is often caused by genetic mutations. Deciphering the mutations in patient-derived tissues has identified potential causative factors ...

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Mediada por CRISPR pérdida de función análisis en gránulo cerebeloso células usando en el útero electroporación basado en la transferencia de genes