El trabajo en el laboratorio de ES con el apoyo de la Fundación Nacional Suiza para la Ciencia. Nos gustaría dar las gracias al Dr. Beat Kunz para obtener ayuda con el rodaje.

<ol>
	<li>Ch&#233;dotal, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Further+tales+of+the+midline.">Further tales of the midline.</a> Current Opinion in Neurobiology. 21, 68-75 (2011).</li><li>Avraham, O., Hadas, Y., Vald, L., Zisman, S., Schejter, A., Visel, A., Klar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+control+of+axonal+guidance+and+sorting+in+dorsal+interneurons+by+the+Lim-HD+proteins+Lhx9+and+Lhx1.">Transcriptional control of axonal guidance and sorting in dorsal interneurons by the Lim-HD proteins Lhx9 and Lhx1.</a> Neural Development. 4, 21 (2009).</li><li>Wilson, N. H., Stoeckli, E. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+type+specific,+traceable+gene+silencing+for+functional+gene+analysis+during+vertebrate+neural+development.">Cell type specific, traceable gene silencing for functional gene analysis during vertebrate neural development.</a> Nucleic Acids Research. 39, e133 (2011).</li><li>Das, R. M., van Hateren, N. J., Howell, G. R., Farrell, E. R., Bangs, F. K., Porteous, V. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+robust+system+for+RNA+interference+in+the+chicken+using+a+modified+microRNA+operon.">A robust system for RNA interference in the chicken using a modified microRNA operon.</a> Developmental Biology. 294, 554-563 (2006).</li><li>Perrin, F. E., Stoeckli, E. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+lipophilic+dyes+in+studies+of+axonal+pathfinding+in+vivo.">Use of lipophilic dyes in studies of axonal pathfinding in vivo.</a> Microscopy Research and Technique. 48, 25-31 (2000).</li><li>Timmer, J., Johnson, J., Niswander, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+in+ovo+electroporation+for+the+rapid+analysis+of+neural-specific+murine+enhancers.">The use of in ovo electroporation for the rapid analysis of neural-specific murine enhancers.</a> Genesis. 29, 123-132 (2001).</li><li>Kieleczawa, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple+modifications+of+the+standard+DNA+sequencing+protocol+allow+for+sequencing+through+siRNA+hairpins+and+other+repeats.">Simple modifications of the standard DNA sequencing protocol allow for sequencing through siRNA hairpins and other repeats.</a> Journal of Biomolecular Techniques. 16, 220-223 (2005).</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> Journal of Morphology. 88, 49-92 (1951).</li><li>Boulland, J., Halasi, G., Kasumacic, N., Glover, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xenotransplantation+of+Human+Stem+Cells+into+the+Chicken+Embryo.">Xenotransplantation of Human Stem Cells into the Chicken Embryo.</a> J. Vis. Exp. (41), e2071 (2010).</li><li>Kim, B. G., Dai, H. -. N., McAtee, M., Vicini, S., Bregman, B. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Labeling+of+dendritic+spines+with+the+carbocyanine+dye+DiI+for+confocal+microscopic+imaging+in+lightly+fixed+cortical+slices.">Labeling of dendritic spines with the carbocyanine dye DiI for confocal microscopic imaging in lightly fixed cortical slices.</a> Journal of Neuroscience Methods. 162, 237-243 (2007).</li><li>Murphy, M. C., Fox, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anterograde+tracing+method+using+DiI+to+label+vagal+innervation+of+the+embryonic+and+early+postnatal+mouse+gastrointestinal+tract.">Anterograde tracing method using DiI to label vagal innervation of the embryonic and early postnatal mouse gastrointestinal tract.</a> Journal of Neuroscience Methods. 163, 213-225 (2007).</li><li>Helms, A. W., Abney, A. L., Ben-Arie, N., Zoghbi, H. Y., Johnson, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autoregulation+and+multiple+enhancers+control+Math1+expression+in+the+developing+nervous+system.">Autoregulation and multiple enhancers control Math1 expression in the developing nervous system.</a> Development. 127, 1185-1196 (2000).</li><li>Li, X., Lufkin, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cre+recombinase+expression+in+the+floorplate,+notochord+and+gut+epithelium+in+transgenic+embryos+driven+by+the+Hoxa-1+enhancer+III.">Cre recombinase expression in the floorplate, notochord and gut epithelium in transgenic embryos driven by the Hoxa-1 enhancer III.</a> Genesis. 26, 121-122 (2000).</li><li>Mauti, O., Baeriswyl, T., Stoeckli, E. T. G. e. n. e. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Silencing+by+Injection+and+Electroporation+of+dsRNA+in+Avian+Embryos.">Silencing by Injection and Electroporation of dsRNA in Avian Embryos.</a> Cold Spring Harbor Protocols. , (2008).</li><li>Krull, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+primer+on+using+in+ovo+electroporation+to+analyze+gene+function.">A primer on using in ovo electroporation to analyze gene function.</a> Developmental Dynamics. 229, 433-439 (2004).</li><li>Cullen, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+and+confirming+the+specificity+of+RNAi+experiments.">Enhancing and confirming the specificity of RNAi experiments.</a> Nature Methods. 3, 677-681 (2006).</li></ol>

No hay conflictos de interés declarado.

Esta simple, basado en vectores de expresión de miARN estrategia artificial puede ser utilizado para la expresión del gen endógeno caída en el tubo neural de pollo. Estas herramientas funcionales ofrecer silenciamiento de genes múltiples, control temporal y la especificidad de tipo celular, para facilitar la dilucidación de complejas vías de desarrollo. En particular, se ha demostrado la utilidad de estos plásmidos en guía de axones comisurales, ya que los plásmidos se pueden utilizar para distintos genes desm...

<table border="1"><tbody><tr><td> Nombre de reactivo </td><td> Empresa </td><td> Número de catálogo </td></tr><tr><td> 0,5 mm capilares de vidrio </td><td> World Precision Instruments </td><td> 1B120F-4 </td></tr><tr><td> Vidrio aguja extractor </td><td> Narishige </td><td> PC-10 </td></tr><tr><td> Electroporador </td><td> BTX </td><td> ECM 830 </td></tr><tr><td> Sylgard de elastómero de silicona </td><td> World Precision Instruments </td><td> SYLG184 </td></tr><tr><td> Alambre de tungsteno, 0,075 mm </td><td> World Precision Instruments </td><td> TGW0325 </td></tr><tr><td> Los alfileres entomológicos, 0,20 mm </td><td> Herramientas Artes Ciencias </td><td> 26002-20 </td></tr><tr><td> Los alfileres entomológicos, 0,10 mm </td><td> Herramientas Artes Ciencias </td><td> 26002-10 </td></tr><tr><td> Tijeras de primavera </td><td> Ciencia Para Fineoles </td><td> 15003-08 </td></tr><tr><td> Dumont # 5 fórceps </td><td> Herramientas Artes Ciencias </td><td> 11252-20 </td></tr><tr><td> Dumont # 55 pinzas </td><td> Herramientas Artes Ciencias </td><td> 11255-20 </td></tr><tr><td> Fast Dil </td><td> Molecular Probes </td><td> D-7756 </td></tr><tr><td> Microscopios de fluorescencia </td><td> Olimpo </td><td> SZX12, BX51 </td></tr></tbody></table>

in ovo electroporation of mirna-based plasmids in the developing neural tube and assessment of phenotypes by dii injection in open-book preparations

Comisurales ED1 neuronas han sido ampliamente estudiados para elucidar los mecanismos que subyacen guía de axones durante el desarrollo 1,2. Estas neuronas se localizan en la médula espinal dorsal y envían sus axones a lo largo de trayectorias estereotipados. Axones de la comisura ventral inicialmente proyectar hacia y luego a través de la placa del piso. Después de cruzar la línea media, estos axones hacer un giro brusco rostral y proyecto longitudinalmente hacia el cerebro. Cada uno de estos pasos está regulado por las actividades coordinadas de señales de orientación de atracción y repulsión. La correcta interpretación de estas señales es crucial para la orientación de los axones a lo largo de su ruta demarcada. Por lo tanto, la contribución fisiológica de una molécula particular para guía de axones de la comisura está idealmente investigado en el contexto de la embrión vivo. Por consiguiente, desmontables de genes in vivo deben ser controlados con precisión con el fin de distinguir cuidadosamente las actividades de orientación axón de genes que pueden jugar múltiplesfunciones durante el desarrollo. Aquí se describe un método para la expresión de gen desmontables en el tubo neural de pollo en un tipo de células específicas, de manera rastreable. Usamos nuevos vectores plasmídicos 3 albergar celulares específicos de tipo promotores / potenciadores que dirigen la expresión de un marcador de la proteína fluorescente, seguido directamente por un transcrito de miR30-RNAi 4 (localizado dentro de la UTR 3 &#39;del ADNc que codifica la proteína fluorescente) ( Figura 1). Cuando electroporación en el tubo neural en desarrollo, estos vectores provocar downregulation eficiente de la expresión génica y expresar proteínas marcadoras fluorescentes brillantes para permitir el rastreo directo de las células que experimentan desmontables 3. Mezclando diferentes vectores de RNAi antes de la electroporación permite la caída simultánea de dos o más genes en regiones independientes de la médula espinal. Esto permite complejas interacciones celulares y moleculares que se examinaron durante el desarrollo, de una manera que es rápida, simple, preciso y barato. En combinación con Dil trazado de trayectorias de axones comisurales en preparaciones de libro abierto 5, este método es una herramienta útil para estudios in vivo de los mecanismos celulares y moleculares de crecimiento de los axones de la comisura y orientación. En principio, cualquier promotor / potenciador se podría utilizar, lo que podría hacer la técnica más ampliamente aplicable para estudios in vivo de la función de genes durante el desarrollo 6. Este primer video muestra cómo controlar y huevos de ventana, la inyección de los plásmidos de ADN en el tubo neural y el procedimiento de electroporación. Para investigar guía de axones comisurales, la médula espinal se retira del embrión como una preparación a libro abierto, fijado, e inyectados con Dil, para permitir que las vías axonales a ser rastreado. La médula espinal está montado entre cubreobjetos y se visualizaron mediante microscopía confocal.

Watch this Scientific Journal Video about In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations at JoVE.c

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

Un método por el cual la expresión de genes en el tubo neural puede ser regulada hacia abajo en un tipo de células específicas, de manera detectable se describe. Demostramos cómo<em&gt; In ovo</emElectroporación&gt; de base microRNA-plásmidos que provocan interferencia de ARN espaciotemporalmente controlada puede ser usada para investigar guiado de los axones de la comisura en el tubo neural en desarrollo.

En electroporación in ovo de base miARN plásmidos en el tubo neural en desarrollo y evaluación de fenotipos por inyección de Dil en los preparativos libro abierto

Commissural dI1 neurons have been extensively studied to elucidate the mechanisms underlying axon guidance during development1,2. These neurons are ...

in-ovo-electroporation-mirna-based-plasmids-developing-neural-tube

Research

JoVE Journal

Neuroscience

In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

16.4K vistas.  University of Zurich. Un método por el cual la expresión de genes en el tubo neural puede ser regulada hacia abajo en un tipo de células específicas, de manera detectable se describe. Demostramos cómo In ovo de base microRNA-plásmidos que provocan interferencia de ARN espaciotemporalmente controlada puede ser usada para investigar guiado de los axones de la comisura en el tubo neural en desarrollo.

Video: In ovo Electroporation of miRNA-based Plasmids in the Developing Neural Tube and Assessment of Phenotypes by DiI Injection in Open-book Preparations

Combining Behavioral Endocrinology and Experimental Economics: Testosterone and Social Decision Making

Behavioral endocrinological research in humans as well as in animals suggests that testosterone plays a key role in social interactions. Studies in rodents have shown a direct link between testosterone and aggressive behavior1 and folk wisdom adapts these findings to humans, suggesting that testosterone induces antisocial, egoistic or even aggressive behavior2. However, many researchers doubt a direct testosterone-aggression link in humans, arguing instead that testosterone is primarily involved in status-related behavior3,4. As a high status can also be achieved by aggressive and antisocial means it can be difficult to distinguish between anti-social and status seeking behavior.
We therefore set up an experimental environment, in which status can only be achieved by prosocial means. In a double-blind and placebo-controlled experiment, we administered a single sublingual dose of 0.5 mg of testosterone (with a hydroxypropyl-&beta;-cyclodextrin carrier) to 121 women and investigated their social interaction behavior in an economic bargaining paradigm. Real monetary incentives are at stake in this paradigm; every player A receives a certain amount of money and has to make an offer to another player B on how to share the money. If B accepts, she gets what was offered and player A keeps the rest. If B refuses the offer, nobody gets anything. A status seeking player A is expected to avoid being rejected by behaving in a prosocial way, i.e. by making higher offers.
The results show that if expectations about the hormone are controlled for, testosterone administration leads to a significant increase in fair bargaining offers compared to placebo. The role of expectations is reflected in the fact that subjects who report that they believe to have received testosterone make lower offers than those who say they believe that they were treated with a placebo. These findings suggest that the experimental economics approach is sensitive for detecting neurobiological effects as subtle as those achieved by administration of hormones. Moreover, the findings point towards the importance of both psychosocial as well as neuroendocrine factors in determining the influence of testosterone on human social behavior.

The procedure described in this protocol shows that testosterone administration and folk beliefs about testosterone may be associated with directly opposed social behaviors.

La combinación del comportamiento de Endocrinología Experimental y Economía: Decisión de la testosterona y sociales que

Behavioral endocrinological research in humans as well as in animals suggests that testosterone plays a key role in social interactions. Studies in ...

Investigación

Neurociencias

Time-lapse Live Imaging of Clonally Related Neural Progenitor Cells in the Developing Zebrafish Forebrain

Precise patterns of division, migration and differentiation of neural progenitor cells are crucial for proper brain development and function1,2. To understand the behavior of neural progenitor cells in the complex in vivo environment, time-lapse live imaging of neural progenitor cells in an intact brain is critically required. In this video, we exploit the unique features of zebrafish embryos to visualize the development of forebrain neural progenitor cells in vivo. We use electroporation to genetically and sparsely label individual neural progenitor cells. Briefly, DNA constructs coding for fluorescent markers were injected into the forebrain ventricle of 22 hours post fertilization (hpf) zebrafish embryos and electric pulses were delivered immediately. Six hours later, the electroporated zebrafish embryos were mounted with low melting point agarose in glass bottom culture dishes. Fluorescently labeled neural progenitor cells were then imaged for 36hours with fixed intervals under a confocal microscope using water dipping objective lens. The present method provides a way to gain insights into the in vivo development of forebrain neural progenitor cells and can be applied to other parts of the central nervous system of the zebrafish embryo.

The present video demonstrates a method which takes advantage of the combination of electroporation and confocal microscopy to perform live imaging on individual neural progenitor cells in the developing zebrafish forebrain. In vivo analysis of the development of forebrain neural progenitor cells at a clonal level can be achieved in this way.

Time-lapse de imágenes en vivo de la relación clonal con células progenitoras neurales en el cerebro anterior El desarrollo de pez cebra

Precise patterns of division, migration and differentiation of neural progenitor cells are crucial for proper brain development and function1,2. To ...

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural connectivity form during development. In mice, retinofugal projections are arranged in a topographic manner and form eye-specific layers in the Lateral Geniculate Nucleus (dLGN) of the thalamus and the Superior Colliculus (SC). The development of these precise patterns of retinofugal projections has typically been studied by labeling populations of RGCs with fluorescent dyes and tracers, such as horseradish peroxidase1-4. However, these methods are too coarse to provide insight into developmental changes in individual RGC axonal arbor morphology that are the basis of retinotopic map formation. They also do not allow for the genetic manipulation of RGCs.
Recently, electroporation has become an effective method for providing precise spatial and temporal control for delivery of charged molecules into the retina5-11. Current retinal electroporation protocols do not allow for genetic manipulation and tracing of retinofugal projections of a single or small cluster of RGCs in postnatal mice. It has been argued that postnatal in vivo electroporation is not a viable method for transfecting RGCs since the labeling efficiency is extremely low and hence requires targeting at embryonic ages when RGC progenitors are undergoing differentiation and proliferation6. 
In this video we describe an in vivo electroporation protocol for targeted delivery of genes, shRNA, and fluorescent dextrans to murine RGCs postnatally. This technique provides a cost effective, fast and relatively easy platform for efficient screening of candidate genes involved in several aspects of neural development including axon retraction, branching, lamination, regeneration and synapse formation at various stages of circuit development. In summary we describe here a valuable tool which will provide further insights into the molecular mechanisms underlying sensory map development.

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

We demonstrate an in vivo electroporation protocol for transfecting single or small clusters of retinal ganglion cells (RGCs) and other retinal cell types in postnatal mice over a wide range of ages. The ability to label and genetically manipulate postnatal RGCs in vivo is a powerful tool for developmental studies.

La transfección de células de ratón del ganglio de la retina por In vivo La electroporación

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural ...

In vivo Electroporation of Developing Mouse Retina

The functional characterization of genes expressed during mammalian retinal development remains a significant challenge. Gene targeting to generate constitutive or conditional loss of function knockouts remains cost and labor intensive, as well as time consuming. Adding to these challenges, retina expressed genes may have essential roles outside the retina leading to unintended confounds when using a knockout approach. Furthermore, the ability to ectopically express a gene in a gain of function experiment can be extremely valuable when attempting to identify a role in cell fate specification and/or terminal differentiation.
We present a method for the rapid and efficient incorporation of DNA plasmids into the neonatal mouse retina by electroporation. The application of short electrical impulses above a certain field strength results in a transient increase in plasma membrane permeability, facilitating the transfer of material across the membrane 1,2,3,4. Groundbreaking work demonstrated that electroporation could be utilized as a method of gene transfer into mammalian cells by inducing the formation of hydrophilic plasma membrane pores allowing the passage of highly charged DNA through the lipid bilayer 5. Continuous technical development has resulted in the viability of electroporation as a method for in vivo gene transfer in multiple mouse tissues including the retina, the method for which is described herein 6, 7, 8, 9, 10. 
DNA solution is injected into the subretinal space so that DNA is placed between the retinal pigmented epithelium and retina of the neonatal (P0) mouse and electrical pulses are applied using a tweezer electrode. The lateral placement of the eyes in the mouse allows for the easy orientation of the tweezer electrode to the necessary negative pole-DNA-retina-positive pole alignment. Extensive incorporation and expression of transferred genes can be identified by postnatal day 2 (P2). Due to the lack of significant lateral migration of cells in the retina, electroporated and non-electroporated regions are generated. Non-electroporated regions may serve as internal histological controls where appropriate. 
Retinal electroporation can be used to express a gene under a ubiquitous promoter, such as CAG, or to disrupt gene function using shRNA constructs or Cre-recombinase. More targeted expression can be achieved by designing constructs with cell specific gene promoters. Visualization of electroporated cells is achieved using bicistronic constructs expressing GFP or by co-electroporating a GFP expression construct. Furthermore, multiple constructs may be electroporated for the study of combinatorial gene effects or simultaneous gain and loss of function of different genes. Retinal electroporation may also be utilized for the analysis of genomic cis-regulatory elements by generating appropriate expression constructs and deletion mutants. Such experiments can be used to identify cis-regulatory regions sufficient or required for cell specific gene expression 11. Potential experiments are limited only by construct availability.

In vivo Electroporation of Developing Mouse Retina

A method for the incorporation of plasmid DNA into murine retinal cells for the purpose of performing either gain- or loss of function studies in vivo is presented. This method capitalizes on the transient increase in permeability of cell plasma membranes induced by the application of an external electrical field.

En electroporación in vivo de la retina del ratón en desarrollo

The functional characterization of genes expressed during mammalian retinal development remains a significant challenge.  Gene targeting to generate ...

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and the organ of Corti in the coiled cochlea. The cristae and maculae contain vestibular hair cells that transduce mechanical stimuli to subserve the special sense of balance, while auditory hair cells in the organ of Corti are the primary transducers for hearing 1. Cell fate specification in these sensory epithelia and morphogenesis of the semicircular canals and cochlea take place during the second week of gestation in the mouse and are largely completed before birth 2,3. Developmental studies of the mouse inner ear are routinely conducted by harvesting transgenic embryos at different embryonic or postnatal stages to gain insight into the molecular basis of cellular and/or morphological phenotypes 4,5. We hypothesize that gene transfer to the developing mouse inner ear in utero in the context of gain- and loss-of-function studies represents a complimentary approach to traditional mouse transgenesis for the interrogation of the genetic mechanisms underlying mammalian inner ear development6.
The experimental paradigm to conduct gene misexpression studies in the developing mouse inner ear demonstrated here resolves into three general steps: 1) ventral laparotomy; 2) transuterine microinjection; and 3) in vivo electroporation. Ventral laparotomy is a mouse survival surgical technique that permits externalization of the uterus to gain experimental access to the implanted embryos7. Transuterine microinjection is the use of beveled, glass capillary micropipettes to introduce expression plasmid into the lumen of the otic vesicle or otocyst. In vivo electroporation is the application of square wave, direct current pulses to drive expression plasmid into progenitor cells8-10. 
We previously described this electroporation-based gene transfer technique and included detailed notes on each step of the protocol11. Mouse experimental embryological techniques can be difficult to learn from prose and still images alone. In the present work, we demonstrate the 3 steps in the gene transfer procedure. Most critically, we deploy digital video microscopy to show precisely how to: 1) identify embryo orientation in utero; 2) reorient embryos for targeting injections to the otocyst; 3) microinject DNA mixed with tracer dye solution into the otocyst at embryonic days 11.5 and 12.5; 4) electroporate the injected otocyst; and 5) label electroporated embryos for postnatal selection at birth. We provide representative examples of successfully transfected inner ears; a pictorial guide to the most common causes of otocyst mistargeting; discuss how to avoid common methodological errors; and present guidelines for writing an in utero gene transfer animal care protocol.

Gene Transfer to the Developing Mouse Inner Ear by In Vivo Electroporation

The mouse inner ear is a placode-derived sensory organ whose developmental program is elaborated during gestation. We define an in utero gene transfer technique consisting of three steps: mouse ventral laparotomy, transuterine microinjection, and in vivo electroporation. We use digital video microscopy to demonstrate the critical experimental embryological techniques.

Transferencia de genes a la oreja del ratón en desarrollo por el interior<em&gt; En Vivo</em&gt; La electroporación

The mammalian inner ear has 6 distinct sensory epithelia: 3 cristae in the ampullae of the semicircular canals; maculae in the utricle and saccule; and ...

High-resolution Live Imaging of Cell Behavior in the Developing Neuroepithelium

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central nervous system (CNS). Although much is known about the molecular mechanisms that pattern the spinal cord and elicit neuronal differentiation1, 2, we lack a deep understanding of these early events at the level of cell behavior. It is thus critical to study the behavior of neural progenitors in real time as they undergo neurogenesis.
In the past, real-time imaging of early embryonic tissue has been limited by cell/tissue viability in culture as well as the phototoxic effects of fluorescent imaging. Here we present a novel assay for imaging such tissue for long periods of time, utilizing a novel ex vivo slice culture protocol and wide-field fluorescence microscopy (Fig. 1). This approach achieves long-term time-lapse monitoring of chick embryonic spinal cord progenitor cells with high spatial and temporal resolution.
This assay may be modified to image a range of embryonic tissues3, 4 In addition to the observation of cellular and sub-cellular behaviors, the development of novel and highly sensitive reporters for gene activity (for example, Notch signaling5) makes this assay a powerful tool with which to understand how signaling regulates cell behavior during embryonic development.

Imaging embryonic tissue in real-time is challenging over long periods of time. Here we present an assay for monitoring cellular and sub-cellular changes in chick spinal cord for long periods with high spatial and temporal resolution. This technique can be adapted for other regions of the nervous system and developing embryo.

Imágenes de alta resolución en vivo del comportamiento de las células en el desarrollo de neuroepitelio

The embryonic spinal cord consists of cycling neural progenitor cells that give rise to a large percentage of the neuronal and glial cells of the central ...

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms1-3. The dysfunction of ventral midbrain dopaminergic neurons is implicated in Parkinson's disease, Schizophrenia, depression, and dementia1-5. Thus, studying the regulation of midbrain dopaminergic neuron differentiation could not only provide important insight into mechanisms regulating midbrain development and neural progenitor fate specification, but also help develop new therapeutic strategies for treating a variety of human neurological disorders.
Dopaminergic neurons differentiate from neural progenitors lining the ventricular zone of embryonic ventral midbrain. The development of neural progenitors is controlled by gene expression programs6,7. Here we report techniques utilizing electroporation to express genes specifically in the midbrain of Hamburger Hamilton (HH) stage 11 (thirteen somites, 42 hours) chick embryos8,9. The external development of chick embryos allows for convenient experimental manipulations at specific embryonic stages, with the effects determined at later developmental time points10-13. Chick embryonic neural tubes earlier than HH stage 13 (nineteen somites, 48 hours) consist of multipotent neural progenitors that are capable of differentiating into distinct cell types of the nervous system. The pCAG vector, which contains both a CMV promoter and a chick &beta;-actin enhancer, allows for robust expression of Flag or other epitope-tagged constructs in embryonic chick neural tubes14. In this report, we emphasize special measures to achieve regionally restricted gene expression in embryonic midbrain dopaminergic neuron progenitors, including how to inject DNA constructs specifically into the embryonic midbrain region and how to pinpoint electroporation with small custom-made electrodes. Analyzing chick midbrain at later stages provides an excellent in vivo system for plasmid vector-mediated gain-of-function and loss-of-function studies of midbrain development. Modification of the experimental system may extend the assay to other parts of the nervous system for performing fate mapping analysis and for investigating the regulation of gene expression.

In ovo Electroporation in Chick Midbrain for Studying Gene Function in Dopaminergic Neuron Development

To assess the function and the regulation of genes during the development of midbrain dopaminergic neurons, we describe a method that involves in ovo electroporation of plasmid DNA constructs into embryonic chick ventral midbrain dopaminergic neuron progenitors. This technique can be used to achieve efficient expression of genes of interest to study different aspects of midbrain development and dopaminergic neuron differentiation.

En electroporación in ovo en el mesencéfalo polluelo para estudiar la función génica en el desarrollo neuronal dopaminérgica

Dopaminergic neurons located in the ventral midbrain control movement, emotional behavior, and reward mechanisms1-3. The dysfunction of ventral midbrain ...

Expansion of Embryonic and Adult Neural Stem Cells by In Utero Electroporation or Viral Stereotaxic Injection

Somatic stem cells can divide to generate additional stem cells (expansion) or more differentiated cell types (differentiation), which is fundamental for tissue formation during embryonic development and tissue homeostasis during adulthood 1. Currently, great efforts are invested towards controlling the switch of somatic stem cells from expansion to differentiation because this is thought to be fundamental for developing novel strategies for regenerative medicine 1,2. However, a major challenge in the study and use of somatic stem cell is that their expansion has been proven very difficult to control.
Here we describe a system that allows the control of neural stem/progenitor cell (altogether referred to as NSC) expansion in the mouse embryonic cortex or the adult hippocampus by manipulating the expression of the cdk4/cyclinD1 complex, a major regulator of the G1 phase of the cell cycle and somatic stem cell differentiation 3,4. Specifically, two different approaches are described by which the cdk4/cyclinD1 complex is overexpressed in NSC in vivo. By the first approach, overexpression of the cell cycle regulators is obtained by injecting plasmids encoding for cdk4/cyclinD1 in the lumen of the mouse telencephalon followed by in utero electroporation to deliver them to NSC of the lateral cortex, thus, triggering episomal expression of the transgenes 5-8. By the second approach, highly concentrated HIV-derived viruses are stereotaxically injected in the dentate gyrus of the adult mouse hippocampus, thus, triggering constitutive expression of the cell cycle regulators after integration of the viral construct in the genome of infected cells 9. Both approaches, whose basic principles were already described by other video protocols 10-14, were here optimized to i) reduce tissue damage, ii) target wide portions of very specific brain regions, iii) obtain high numbers of manipulated cells within each region, and iv) trigger high expression levels of the transgenes within each cell. Transient overexpression of the transgenes using the two approaches is obtained by different means i.e. by natural dilution of the electroporated plasmids due to cell division or tamoxifen administration in Cre-expressing NSC infected with viruses carrying cdk4/cyclinD1 flanked by loxP sites, respectively 9,15.
These methods provide a very powerful platform to acutely and tissue-specifically manipulate the expression of any gene in the mouse brain. In particular, by manipulating the expression of the cdk4/cyclinD1 complex, our system allows the temporal control of NSC expansion and their switch to differentiation, thus, ultimately increasing the number of neurons generated in the mammalian brain. Our approach may be critically important for basic research and using somatic stem cells for therapy of the mammalian central nervous system while providing a better understanding of i) stem cell contribution to tissue formation during development, ii) tissue homeostasis during adulthood, iii) the role of adult neurogenesis in cognitive functions, and perhaps, iv) better using somatic stem cells in models of neurodegenerative diseases.

Expansion of Embryonic and Adult Neural Stem Cells by In Utero Electroporation or Viral Stereotaxic Injection

Controlling the expansion of somatic stem cells is a major factor hampering their study and use in therapy. Here we describe a system to temporally control neural stem cells expansion during development and adulthood, which can be used to increase the number of neurons generated in the mouse brain.

La expansión de las células madre embrionarias y adultas neurales por<em&gt; In Utero</em&gt; La electroporación o inyección estereotáxica Viral

Somatic stem cells can divide to generate additional stem cells (expansion) or more differentiated cell types (differentiation), which is fundamental for ...

Genetic Manipulation of the Mouse Developing Hypothalamus through In utero Electroporation

Genetic modification of specific regions of the developing mammalian brain is a very powerful experimental approach. However, generating novel mouse mutants is often frustratingly slow. It has been shown that access to the mouse brain developing in utero with reasonable post-operatory survival is possible. Still, results with this procedure have been reported almost exclusively for the most superficial and easily accessible part of the developing brain, i.e. the cortex. The thalamus, a narrower and more medial region, has proven more difficult to target. Transfection into deeper nuclei, especially those of the hypothalamus, is perhaps the most challenging and therefore very few results have been reported. Here we demonstrate a procedure to target the entire hypothalamic neuroepithelium or part of it (hypothalamic regions) for transfection through electroporation. The keys to our approach are longer narcosis times, injection in the third ventricle, and appropriate kind and positioning of the electrodes. Additionally, we show results of targeting and subsequent histological analysis of the most recessed hypothalamic nucleus, the mammillary body.

Genetic Manipulation of the Mouse Developing Hypothalamus through In utero Electroporation

Despite the functional and medical importance of the hypothalamus, in utero genetic manipulation of its development has rarely been attempted. We show a detailed procedure for in utero electroporation into the mouse hypothalamus and show representative results of total and partial (regional) hypothalamic transfection.

La manipulación genética del ratón en desarrollo a través de Hipotálamo<em&gt; En el útero</em&gt; La electroporación

Genetic  modification of specific regions of the developing mammalian brain is a very  powerful experimental approach. However, generating novel mouse ...

Ex Vivo Preparations of the Intact Vomeronasal Organ and Accessory Olfactory Bulb

The mouse accessory olfactory system (AOS) is a specialized sensory pathway for detecting nonvolatile social odors, pheromones, and kairomones. The first neural circuit in the AOS pathway, called the accessory olfactory bulb (AOB), plays an important role in establishing sex-typical behaviors such as territorial aggression and mating. This small (&#60;1 mm3) circuit possesses the capacity to distinguish unique behavioral states, such as sex, strain, and stress from chemosensory cues in the secretions and excretions of conspecifics. While the compact organization of this system presents unique opportunities for recording from large portions of the circuit simultaneously, investigation of sensory processing in the AOB remains challenging, largely due to its experimentally disadvantageous location in the brain. Here, we demonstrate a multi-stage dissection that removes the intact AOB inside a single hemisphere of the anterior mouse skull, leaving connections to both the peripheral vomeronasal sensory neurons (VSNs) and local neuronal circuitry intact. The procedure exposes the AOB surface to direct visual inspection, facilitating electrophysiological and optical recordings from AOB circuit elements in the absence of anesthetics. Upon inserting a thin cannula into the vomeronasal organ (VNO), which houses the VSNs, one can directly expose the periphery to social odors and pheromones while recording downstream activity in the AOB. This procedure enables controlled inquiries into AOS information processing, which can shed light on mechanisms linking pheromone exposure to changes in behavior.

Ex Vivo Preparations of the Intact Vomeronasal Organ and Accessory Olfactory Bulb

The mouse accessory olfactory bulb (AOB) has been difficult to study in the context of sensory coding. Here, we demonstrate a dissection that produces an ex vivo preparation in which AOB neurons remain functionally connected to their peripheral inputs, facilitating research into information processing of mouse pheromones and kairomones.

Ex vivo la Producción de la Bombilla órgano vomeronasal y accesorios olfativa Intacto

The mouse accessory olfactory system (AOS) is a specialized sensory pathway for detecting nonvolatile social odors, pheromones, and kairomones. The first ...