Este trabajo fue apoyado por una beca de la DFG en GMT

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J., Sink, H., Kolodkin, A. L., Goodman, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Semaphorin+II+can+function+as+a+selective+inhibitor+of+specific+synaptic+arborizations.">Semaphorin II can function as a selective inhibitor of specific synaptic arborizations.</a> Cell. 81, 631-639 (1995).</li><li>Murray, M. J., Whitington, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+roundabout+on+growth+cone+dynamics,+filopodial+length,+and+growth+cone+morphology+at+the+midline+and+throughout+the+neuropile.">Effects of roundabout on growth cone dynamics, filopodial length, and growth cone morphology at the midline and throughout the neuropile.</a> Journal of Neuroscience. 19, 7901-7912 (1999).</li><li>Murray, M. J., Merritt, D. J., Brand, A. H., Whitington, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+dynamics+of+axon+pathfinding+in+the+Drosophilia+CNS:+a+time-lapse+study+of+an+identified+motorneuron.">In vivo dynamics of axon pathfinding in the Drosophilia CNS: a time-lapse study of an identified motorneuron.</a> J. Neurobiol. 37, 607-621 (1998).</li><li>Patel, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+neuronal+subsets+and+other+cell+types+in+whole-mount+Drosophila+embryos+and+larvae+using+antibody+probes.">Imaging neuronal subsets and other cell types in whole-mount Drosophila embryos and larvae using antibody probes.</a> Methods Cell Biol. 44, 445-487 (1994).</li><li>Rickert, C., Kunz, T., Harris, K. -. L., Whitington, P. M., Technau, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+characterization+of+the+entire+interneuron+population+reveals+principles+of+neuromere+organization+in+the+ventral+nerve+cord+of+Drosophila.">Morphological characterization of the entire interneuron population reveals principles of neuromere organization in the ventral nerve cord of Drosophila.</a> Journal of Neuroscience. 31, 15870-15883 (2011).</li><li>Thomas, J. B., Bastiani, M. J., Bate, M., Goodman, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+grasshopper+to+Drosophila:+a+common+plan+for+neuronal+development.">From grasshopper to Drosophila: a common plan for neuronal development.</a> Nature. 310, 203-207 (1984).</li><li>Whitington, P., Harris, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+axonogenesis+in+the+embryo+of+a+primitive+insect,+the+silverfish+Ctenolepisma+longicaudata.">Early axonogenesis in the embryo of a primitive insect, the silverfish Ctenolepisma longicaudata.</a> Development Genes and Evolution. 205 (5-6), 272-281 (1996).</li><li>Whitington, P., Meier, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Segmentation,+neurogenesis+and+formation+of+early+axonal+pathways+in+the+centipede,+Ethmostigmus+rubripes+(Brandt).">Segmentation, neurogenesis and formation of early axonal pathways in the centipede, Ethmostigmus rubripes (Brandt).</a> Development Genes and Evolution. 199, 349-363 (1991).</li><li>Whitington, P. M., Seifert, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axon+growth+from+limb+motorneurons+in+the+locust+embryo:+the+effect+of+target+limb+removal+on+the+pattern+of+axon+branching+in+the+periphery.">Axon growth from limb motorneurons in the locust embryo: the effect of target limb removal on the pattern of axon branching in the periphery.</a> Developmental Biology. 106, 438-449 (1984).</li><li>Whitington, P. M., Leach, D., Sandeman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolutionary+change+in+neural+development+within+the+arthropods:+axonogenesis+in+the+embryos+of+two+crustaceans.">Evolutionary change in neural development within the arthropods: axonogenesis in the embryos of two crustaceans.</a> Development. 118, 449-461 (1993).</li><li>Williams, D. W., Tyrer, M., Shepherd, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tau+and+tau+reporters+disrupt+central+projections+of+sensory+neurons+in+Drosophila.">Tau and tau reporters disrupt central projections of sensory neurons in Drosophila.</a> J. Comp. Neurol. 428, 630-640 (2000).</li></ol>

Los autores declaran que no tienen intereses en conflicto financieros.

Una ventaja importante de Drosophila como sistema modelo es que permite el análisis del desarrollo y la función en el nivel de células individuales. Esto es especialmente útil en relación con el sistema nervioso, donde la diversidad de tipos de células es excepcionalmente alta y la función y la morfología de las células vecinas pueden ser totalmente diferentes. El método que aquí presentamos permite el etiquetado de las neuronas individuales con un colorante que puede ser...

El conocimiento de la morfología neuronal a nivel de células individuales es una condición previa esencial para la comprensión de la conectividad neuronal y la función del SNC. Así, desde los primeros días de la neurociencia, los investigadores han tratado de desarrollar técnicas de marcaje de células individuales (véase 7 para un tratamiento histórico de este número). Los métodos clásicos, tales como la tinción de Golgi proporcionar una excelente resolución de la morfología neuronal, pero no son adecuados si se busca una etiqueta en un tipo particular de neurona en forma dirigida, como la tinción se produce de una manera aleatoria. El desarrollo de métodos para la tinción de las células individuales por inyección intracelular o juxtacellular de colorantes de un microelectrodo se dirigió a la exigencia de un etiquetado específico. La aplicación de una sola neurona de inyección de tinte para Drosophila presentó un desafío importante, debido al tamaño pequeño de tanto el organismo y sus neuronas. Sin embargo, la tinción única neurona de embriones de Drosophila </em&gt; Neuronas se logró a mediados de la década de 1980 en el laboratorio de Corey Goodman 15. Mientras que el método ha sido eminentemente útil y ha dado algunas ideas clave sobre los mecanismos para el desarrollo neuronal en Drosophila en los últimos 20-30 años (por ejemplo, 2, 10), muchos trabajadores se han negado a ello, en gran parte debido a sus exigencias técnicas. La disponibilidad en los años más recientes de técnicas genéticas para el etiquetado neuronal en Drosophila también ha contribuido a la impopularidad de la inyección de un solo tinte neurona. GAL4 expresión dirigida de los constructos de GFP específicos de membrana puede proporcionar una excelente resolución de la morfología neuronal 1, 20. Sin embargo, este método tiene ciertas limitaciones: la expresión a menudo inevitable de GFP en las células múltiples puede oscurecer la estructura de las neuronas individuales, y una línea GAL4 conductor puede no estar disponible para conducir la expresión en una neurona particular de interés. El MARCM (Análisis Mosaico con un representantemarcador de células ressible) 8 método puede proporcionar un etiquetado de esencialmente cualquier neurona en el nivel de células individuales, pero no puede ser utilizado con éxito en el embrión y larva temprana debido a la lenta rotación de la proteína GAL80. Dadas estas limitaciones de etiquetado genética, creemos que la inyección neurona solo tinte en el embrión de Drosophila sigue siendo una técnica valiosa y merece una aplicación más amplia. Para promover este objetivo, ofrecemos aquí una descripción detallada del método. Una ilustración de su potencia es proporcionada por nuestra cuenta reciente de la morfología de la serie completa de interneuronas en neuromeres abdominales de finales de los años 14 embrión de Drosophila. Este estudio, que reveló tanto la variabilidad morfológica de los distintos tipos de células neuronales y los principios de organización neuromere en el SNC del embrión, no habría sido posible con cualquier otro método de etiquetado disponibles en la actualidad.

<table border="1"><tbody><tr><td> Nombre del reactivo / material </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios </td></tr><tr><td></td><td></td><td></td><td> REACTIVOS </td></tr><tr><td> DAB </td><td> Sigma-Aldrich </td><td> <a href="http://www.sigmaaldrich.com/catalog/product/sigma/d5905" target="_blank">D-5905</a> </td><td> 2-3 mg / ml en 100 mM Tris-HCl, pH 7,4 </td></tr><tr><td> Dil </td><td> Invitrogen / Molecular Probes </td><td> <a href="http://products.invitrogen.com/ivgn/product/D282" target="_blank">D-282</a> </td><td> 1 mg / ml en etanol </td></tr><tr><td> <a href="http://www.merckmillipore.com/germany/chemicals/formaldehydloesung-min-37-prozent/MDA_CHEM-104002/p_Wt6b.s1L6pAAAAEWpOEfVhTl" target="_blank">Formaldehído</a> </td><td> Merck Millipore </td><td></td><td> 7,4% en PBS </td> &lt;/ Tr&gt; <tr><td> Glicerol </td><td> <a href="http://www.carlroth.com/catalogue/" target="_blank">Roth</a> </td><td> 3783 </td><td> 70% en PBS </td></tr><tr><td> Heptano Glue </td><td> Beiersdorf AG </td><td> Cello 31-39-30 * </td><td> diluir ca. 1 a 1 con n-heptano </td></tr><tr><td> PBS </td><td></td><td></td><td> 1x </td></tr><tr><td> TRIS </td><td> <a href="http://www.carlroth.com/catalogue/" target="_blank">Roth</a> </td><td> 4855 </td><td></td></tr><tr><td> Vectashield </td><td> Vector Laboratories </td><td> <a href="http://www.vectorlabs.com/catalog.aspx?prodID=427" target="_blank">H1000</a> </td><td></td></tr><tr><td></td><td></td><td></td><td> EQUIPO </td></tr><tr><td> Microscopio Confocal </td><td> Leica </td><td> TCS SP2 </td><td> para ver y documentar etiquetados de la fluorescencia </td></tr><tr><td> DC - unamplifier </td><td> Dragan Corporación </td><td> Cornerstone ION-100 </td><td> para llevar a cabo los etiquetados </td></tr><tr><td> Cubreobjetos </td><td> <a href="http://www.menzel.de/" target="_blank">Menzel</a> </td><td> BB018018A1 </td><td> 18 x 18 mm </td></tr><tr><td> Cubreobjetos </td><td> <a href="http://www.menzel.de/" target="_blank">Menzel</a> </td><td> BB024060A1 </td><td> 24 x 60 mm </td></tr><tr><td> Microscopio de disección </td><td> Leica </td><td> MZ8 </td><td> para preparar y diseccionar embriones </td></tr><tr><td> Piso Capilares </td><td> <a href="http://www.hilgenberg-gmbh.de/" target="_blank">Hilgenberg</a> </td><td></td><td> diámetro exterior 1 mm, grosor de 0,1 mm glas </td></tr><tr><td> Inyección Capilares </td><td> Science Products </td><td> 100 GB TF 8P </td><td></td></tr><tr><td> Micromanipulador R </td><td> Leica </td><td></td><td> para llevar a cabo los etiquetados </td></tr><tr><td> Modelo P-97 </td><td> Sutter Instruments </td><td></td><td> para tirar de los capilares </td></tr><tr><td> Diapositivas Objetos </td><td> <a href="http://www.marienfeld-superior.com/" target="_blank">Marienfeld Superior</a> </td><td> 1000000 </td><td></td></tr><tr><td> Microscopio Científico </td><td> Zeiss </td><td> Axioskop 2 MOT </td><td> para ver etiquetados después fotoconversión </td></tr><tr><td> Microscopio Científico </td><td> Olimpo </td><td> BX50 </td><td> para llevar a cabo los etiquetados </td></tr><tr><td> Sony MC3255 cámara de vídeo </td><td> Sony / AVT Horn </td><td> Sony MC3255 </td><td> para grabar etiquetados después de fotoconversión </td></tr></tbody></table> Tabla 1.

labeling of single cells in the central nervous system of drosophila melanogaster

En este artículo se describe cómo etiquetar individualmente las neuronas en el sistema nervioso central embrionario de Drosophila melanogaster por inyección juxtacellular del lipofílico fluorescente Dil marcador de membrana. Este método permite la visualización de la morfología de las células neuronales en gran detalle. Es posible marcar cualquier célula en el SNC: cuerpos celulares de las neuronas diana son visualizadas bajo óptica DIC o por expresión de un marcador genético fluorescente tal como GFP. Después del marcaje, el Dil se puede transformar en una permanente mancha marrón por fotoconversión para permitir la visualización de la morfología celular con luz transmitida y la óptica DIC. Alternativamente, las células marcadas con Dil se puede observar directamente con la microscopía confocal, permite genéticamente introducidos proteínas indicadoras fluorescentes que se colocalizaban. La técnica se puede utilizar en cualquier animal, independientemente del genotipo, haciendo posible el análisis de fenotipos mutantes con una resolución de célula individual.

La Figura 4 ilustra los resultados típicos de la técnica, como se describe aquí. Figura 4A muestra un ejemplo de un Dil llena interneuron único que se photoconverted limpiamente. Es muy bien demuestra la cantidad de detalle que ofrecen estas preparaciones. Cuando se observa bajo la óptica DIC el contexto espacial de la celda marcada dentro del tejido circundante no marcado se hace visible, por ejemplo, la posición del cuerpo de la celda dentro de la corteza y de la proyec...

Watch this Scientific Journal Video about Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster at JoVE.com

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

Se presenta una técnica para el etiquetado de las neuronas individuales en el sistema nervioso central (SNC) de<em&gt; Drosophila</em&gt; Embriones, lo que permite el análisis de la morfología neuronal ya sea por la luz transmitida o microscopía confocal.

El marcaje de células individuales en el Sistema Nervioso Central de<em&gt; Drosophila melanogaster</em

In this  article we describe how to individually label neurons in the embryonic CNS of Drosophila melanogaster by juxtacellular injection of the ...

labeling-single-cells-central-nervous-system-drosophila

Research

JoVE Journal

Neuroscience

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

12.7K vistas.  University of Mainz. Se presenta una técnica para el etiquetado de las neuronas individuales en el sistema nervioso central (SNC) de Drosophila Embriones, lo que permite el análisis de la morfología neuronal ya sea por la luz transmitida o microscopía confocal.

Video: Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

Single Sensillum Recordings in the Insects Drosophila melanogaster and Anopheles gambiae

The sense of smell is essential for insects to find foods, mates, predators, and oviposition sites3. Insect olfactory sensory neurons (OSNs) are enclosed in sensory hairs called sensilla, which cover the surface of olfactory organs. The surface of each sensillum is covered with tiny pores, through which odorants pass and dissolve in a fluid called sensillum lymph, which bathes the sensory dendrites of the OSNs housed in a given sensillum. The OSN dendrites express odorant receptor (OR) proteins, which in insects function as odor-gated ion channels4, 5. The interaction of odorants with ORs either increases or decreases the basal firing rate of the OSN. This neuronal activity in the form of action potentials embodies the first representation of the quality, intensity, and temporal characteristics of the odorant6, 7.
Given the easy access to these sensory hairs, it is possible to perform extracellular recordings from single OSNs by introducing a recording electrode into the sensillum lymph, while the reference electrode is placed in the lymph of the eye or body of the insect. In Drosophila, sensilla house between one and four OSNs, but each OSN typically displays a characteristic spike amplitude. Spike sorting techniques make it possible to assign spiking responses to individual OSNs. This single sensillum recording (SSR) technique monitors the difference in potential between the sensillum lymph and the reference electrode as electrical spikes that are generated by the receptor activity on OSNs1, 2, 8. Changes in the number of spikes in response to the odorant represent the cellular basis of odor coding in insects. Here, we describe the preparation method currently used in our lab to perform SSR on Drosophila melanogaster and Anopheles gambiae, and show representative traces induced by the odorants in a sensillum-specific manner.

Single Sensillum Recordings in the Insects Drosophila melanogaster and Anopheles gambiae

Electrophysiological responses of olfactory sensory neurons to odorants can be measured in insects using single sensillum recordings. In this video article we will demonstrate how to perform single sensillum recordings in the antennae of the vinegar fly (Drosophila melanogaster) and the maxillary palps of the malaria mosquito (Anopheles gambiae).

Grabaciones solo Sensillum en los insectos Drosophila melanogaster Y Anopheles gambiae</em

The sense of smell is essential for insects to find foods, mates, predators, and oviposition sites3. Insect olfactory sensory neurons (OSNs) are enclosed ...

Investigación

Neurociencias

Visualization of the Embryonic Nervous System in Whole-mount Drosophila Embryos

The Drosophila embryo is an attractive model system for investigating the cellular and molecular basis of neuronal development. Here we describe the procedure for the visualization of Drosophila embryonic nervous system using antibodies to neuronal proteins. Since the entire embryonic peripheral nervous and central nervous systems are well characterized at the level of individual cells (Dambly-Chaudi&egrave;re et al., 1986; Bodmer et al., 1987; Bodmer et al., 1989), any aberrations to these systems can be easily identified using antibodies to different neuronal proteins. The developing embryos are collected at certain times to ensure that the embryos are in the proper developmental stages for visualization. After collection, the outer layers of the embryo, the chorion membrane and the vitelline envelope that surrounds the embryo, are removed before fixation. Embryos are then incubated with neuronal antibodies and visualized using fluorescently labeled secondary antibodies. Embryos at stages 12-17 are visualized to access the embryonic nervous system. At stage 12 the CNS germ band starts shortening and by stage 15 the definitive pattern of the commissure has been achieved. By stage 17 the CNS contracts and the PNS is fully developed (Campos-Ortega et al. 1985). Thus changes in the pattern of the PNS and CNS can be easily observed during these developmental stages.

Visualization of the Embryonic Nervous System in Whole-mount Drosophila Embryos

We describe the procedure to prepare staged Drosophila embryos for the visualization of the embryonic nervous system during embryogenesis.

Visualización del sistema nervioso embrionario en Todo el montaje Drosophila Los embriones

The Drosophila embryo is an attractive model system for investigating the cellular and molecular basis of neuronal development. Here we describe the ...

Optic Nerve Transection: A Model of Adult Neuron Apoptosis in the Central Nervous System

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. 
The optic nerve can be accessed within the orbit of the eye and completely transected (axotomized), cutting the axons of the entire RGC population. Optic nerve 
transection is a reproducible model of apoptotic neuronal cell death in the adult CNS 1-4. This model is particularly attractive because the vitreous
 chamber of the eye acts as a capsule for drug delivery to the retina, permitting experimental manipulations via intraocular injections. The diffusion of chemicals 
through the vitreous fluid ensures that they act upon the entire RGC population. Moreover, RGCs can be selectively transfected by applying short interfering RNAs 
(siRNAs), plasmids, or viral vectors to the cut end of the optic nerve 5-7 or injecting vectors into their target, the superior colliculus 8. 
This allows researchers to study apoptotic mechanisms in the desired neuronal population without confounding effects on other bystander neurons or surrounding glia. 
An additional benefit is the ease and accuracy with which cell survival can be quantified after injury. The retina is a flat, layered tissue and RGCs are localized in 
the innermost layer, the ganglion cell layer. The survival of RGCs can be tracked over time by applying a fluorescent tracer (3% Fluorogold) to the cut end of the 
optic nerve at the time of axotomy, or by injecting the tracer into the superior colliculus (RGC target) one week prior to axotomy. The tracer is retrogradely transported, labeling 
the entire RGC population. Because the ganglion cell layer is a monolayer (one cell thick), RGC densities can be quantified in flat-mounted tissue, without the need 
for stereology. Optic nerve transection leads to the apoptotic death of 90% of injured RGCs within 14 days postaxotomy 9-11. RGC apoptosis has a 
characteristic time-course whereby cell death is delayed 3-4 days postaxotomy, after which the cells rapidly degenerate. This provides a time window for 
experimental manipulations directed against pathways involved in apoptosis.

Optic Nerve transection is a widely used model of adult CNS injury. Ninety percent of retinal ganglion cells (RGCs) whose axons are completely transected (axotomy) die within 14 days after axotomy. This model is easily amenable to experimental manipulations and highly reproducible.

La transección del nervio óptico: un modelo de apoptosis neuronal de adultos en el sistema nervioso central

Retinal ganglion cells (RGCs) are CNS neurons that output visual information from the retina to the brain, via the optic nerve. 
The optic nerve can be ...

Multimodal Imaging of Stem Cell Implantation in the Central Nervous System of Mice

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, both in preclinical and clinical studies. However, to date results regarding functional outcome and/or tissue regeneration following stem cell transplantation are quite diverse. Generally, a clinical benefit is observed without profound understanding of the underlying mechanism(s)1. Therefore, multiple efforts have led to the development of different molecular imaging modalities to monitor stem cell grafting with the ultimate aim to accurately evaluate survival, fate and physiology of grafted stem cells and/or their micro-environment. Changes observed in one or more parameters determined by molecular imaging might be related to the observed clinical effect. In this context, our studies focus on the combined use of bioluminescence imaging (BLI), magnetic resonance imaging (MRI) and histological analysis to evaluate stem cell grafting.
BLI is commonly used to non-invasively perform cell tracking and monitor cell survival in time following transplantation2-7, based on a biochemical reaction where cells expressing the Luciferase-reporter gene are able to emit light following interaction with its substrate (e.g. D-luciferin)8, 9. MRI on the other hand is a non-invasive technique which is clinically applicable10 and can be used to precisely locate cellular grafts with very high resolution11-15, although its sensitivity highly depends on the contrast generated after cell labeling with an MRI contrast agent. Finally, post-mortem histological analysis is the method of choice to validate research results obtained with non-invasive techniques with highest resolution and sensitivity. Moreover end-point histological analysis allows us to perform detailed phenotypic analysis of grafted cells and/or the surrounding tissue, based on the use of fluorescent reporter proteins and/or direct cell labeling with specific antibodies.
In summary, we here visually demonstrate the complementarities of BLI, MRI and histology to unravel different stem cell- and/or environment-associated characteristics following stem cell grafting in the CNS of mice. As an example, bone marrow-derived stromal cells, genetically engineered to express the enhanced Green Fluorescent Protein (eGFP) and firefly Luciferase (fLuc), and labeled with blue fluorescent micron-sized iron oxide particles (MPIOs), will be grafted in the CNS of immune-competent mice and outcome will be monitored by BLI, MRI and histology (Figure 1).

This article describes an optimized sequence of events for multimodal imaging of cellular grafts in rodent brain using: (i) in vivo bioluminescence and magnetic resonance imaging, and (ii) post mortem histological analysis. Combining these imaging modalities on a single animal allows cellular graft evaluation with high resolution, sensitivity and specificity.

Imagen multimodal de implante de células madre en el sistema nervioso central de ratones

During the past decade, stem cell transplantation has gained increasing interest as primary or secondary therapeutic modality for a variety of diseases, ...

Production of Lentiviral Vectors for Transducing Cells from the Central Nervous System

Efficient gene delivery in the central nervous system (CNS) is important in studying gene functions, modeling neurological diseases and developing therapeutic approaches. Lentiviral vectors are attractive tools in transduction of neurons and other cell types in CNS as they transduce both dividing and non-dividing cells, support sustained expression of transgenes, and have relatively large packaging capacity and low toxicity 1-3. Lentiviral vectors have been successfully used in transducing many neural cell types in vitro 4-6 and in animals 7-10.
Great efforts have been made to develop lentiviral vectors with improved biosafety and efficiency for gene delivery. The current third generation replication-defective and self-inactivating (SIN) lentiviral vectors are depicted in Figure 1. The required elements for vector packaging are split into four plasmids. In the lentiviral transfer plasmid, the U3 region in the 5' long terminal repeat (LTR) is replaced with a strong promoter from another virus. This modification allows the transcription of the vector sequence independent of HIV-1 Tat protein that is normally required for HIV gene expression 11. The packaging signal (&Psi;) is essential for encapsidation and the Rev-responsive element (RRE) is required for producing high titer vectors. The central polypurine tract (cPPT) is important for nuclear import of the vector DNA, a feature required for transducing non-dividing cells 12. In the 3' LTR, the cis-regulatory sequences are completely removed from the U3 region. This deletion is copied to 5' LTR after reverse transcription, resulting in transcriptional inactivation of both LTRs. Plasmid pMDLg/pRRE contains HIV-1 gag/pol genes, which provide structural proteins and reverse transcriptase. pRSV-Rev encodes Rev which binds to the RRE for efficient RNA export from the nucleus. pCMV-G encodes the vesicular stomatitis virus glycoprotein (VSV-G) that replaces HIV-1 Env. VSV-G expands the tropism of the vectors and allows concentration via ultracentrifugation 13. All the genes encoding the accessory proteins, including Vif, Vpr, Vpu, and Nef are excluded in the packaging system. The production and manipulation of lentiviral vectors should be carried out according to NIH guidelines for research involving recombinant DNA (<a href="http://oba.od.nih.gov/oba/rac/Guidelines/NIH_Guidelines.pdf" target="_blank">http://oba.od.nih.gov/oba/rac/Guidelines/NIH_Guidelines.pdf</a>). An approval from individual Institutional Biological and Chemical Safety Committee may be required before using lentiviral vectors. Lentiviral vectors are commonly produced by cotransfection of 293T cells with lentiviral transfer plasmid and the helper plasmids encoding the proteins required for vector packaging. Many lentiviral transfer plasmids and helper plasmids can be obtained from Addgene, a non-profit plasmid repository (<a href="http://www.addgene.org/" target="_blank">http://www.addgene.org/</a>). Some stable packaging cell lines have been developed, but these systems provide less flexibility and their packaging efficiency generally declines over time 14, 15. Commercially available transfection kits may support high efficiency of transfection 16, but they can be very expensive for large scale vector preparations. Calcium phosphate precipitation methods provide highly efficient transfection of 293T cells and thus provide a reliable and cost effective approach for lentiviral vector production.
In this protocol, we produce lentiviral vectors by cotransfection of 293T cells with four plasmids based on the calcium phosphate precipitation principle, followed by purification and concentration with ultracentrifugation through a 20% sucrose cushion. The vector titers are determined by fluorescence- activated cell sorting (FACS) analysis or by real time qPCR. The production and titration of lentiviral vectors in this protocol can be finished with 9 days. We provide an example of transducing these vectors into murine neocortical cultures containing both neurons and astrocytes. We demonstrate that lentiviral vectors support high efficiency of transduction and cell type-specific gene expression in primary cultured cells from CNS.

In this protocol we describe production, purification and titration of lentiviral vectors. We provide an example of lentiviral vector-mediated gene delivery in primary cultured neurons and astrocytes. Our methods may also apply to other cell types in vitro and in vivo.

La producción de vectores lentivirales de células transductoras del Sistema Nervioso Central

Efficient gene delivery in the central nervous system (CNS) is important in studying gene functions, modeling neurological diseases and developing ...

An Injury Paradigm to Investigate Central Nervous System Repair in Drosophila

An experimental method has been developed to investigate the cellular responses to central nervous system (CNS) injury using the fruit-fly Drosophila. Understanding repair and regeneration in animals is a key question in biology. The damaged human CNS does not regenerate, and understanding how to promote the regeneration is one of main goals of medical neuroscience. The powerful genetic toolkit of Drosophila can be used to tackle the problem of CNS regeneration.
A lesion to the CNS ventral nerve cord (VNC, equivalent to the vertebrate spinal cord) is applied manually with a tungsten needle. The VNC can subsequently be filmed in time-lapse using laser scanning confocal microscopy for up to 24 hr to follow the development of the lesion over time. Alternatively, it can be cultured, then fixed and stained using immunofluorescence to visualize neuron and glial cells with confocal microscopy. Using appropriate markers, changes in cell morphology and cell state as a result of injury can be visualized. With ImageJ and purposely developed plug-ins, quantitative and statistical analyses can be carried out to measure changes in wound size over time and the effects of injury in cell proliferation and cell death. These methods allow the analysis of large sample sizes. They can be combined with the powerful genetics of Drosophila to investigate the molecular mechanisms underlying CNS regeneration and repair.

An Injury Paradigm to Investigate Central Nervous System Repair in Drosophila

An injury paradigm using the Drosophila larval ventral nerve cord to investigate central nervous system regeneration and repair is described. Stabbing followed by laser scanning confocal microscopy in time-lapse and fixed specimens, combined with quantitative analysis with purposefully developed software and genetics, are used to investigate the molecular mechanisms of CNS regeneration and repair.

Un paradigma de Lesiones de investigar reparación del sistema nervioso central en<em&gt; Drosophila</em

An experimental method has been developed to investigate the cellular responses to central nervous system (CNS) injury using the fruit-fly Drosophila. ...

Direct Intraventricular Delivery of Drugs to the Rodent Central Nervous System

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses specifically on antisense oligonucleotides (ASOs), though the techniques shown in the video here can also be used to deliver a plethora of other drugs to the CNS. Antisense oligonucleotides (ASOs) have the capability to knockdown sequence-specific targets 1 as well as shift isoform ratios of specific genes 2. To achieve widespread gene knockdown or splicing in the CNS of mice, the ASOs can be delivered into the brain using two separate routes of administration, both of which we demonstrate in the video.
The first uses Alzet osmotic pumps, connected to a catheter that is surgically implanted into the lateral ventricle. This allows the ASOs to be continuously infused into the CNS for a designated period of time. The second involves a single bolus injection of a high concentration of ASO into the right lateral ventricle. Both methods use the mouse cerebral ventricular system to deliver the ASO to the entire brain and spinal cord, though depending on the needs of the study, one method may be preferred over the other.

We describe a method to target drugs to the central nervous system by either implanting a catheter or performing a bolus injection into the right lateral ventricle in mice. We focus specifically on the delivery of antisense oligonucleotides. This technique is readily adaptable to other drugs and to rats.

Entrega intraventricular directa de medicamentos al roedor Sistema Nervioso Central

Due to an inability to cross the blood brain barrier, certain drugs need to be directly delivered into the central nervous system (CNS). Our lab focuses ...

In vivo Interrogation of Central Nervous System Translatome by Polyribosome Fractionation

Multiple processes are involved in gene expression including transcription, translation and stability of mRNAs and proteins. Each of these steps are tightly regulated, affecting the final dynamics of protein abundance. Various regulatory mechanisms exist at the translation step, rendering mRNA levels alone an unreliable indicator of gene expression. In addition, local regulation of mRNA translation has been particularly implicated in neuronal functions, shifting &#39;translatomics&#39; to the focus of attention in neurobiology. The presented method can be used to bridge transcriptomics and proteomics.
Here we describe essential modifications to the technique of polyribosome fractionation, which interrogates the translatome based on the association of actively translated mRNAs to multiple ribosomes and their differential sedimentation in sucrose gradients. Traditionally, working with in vivo samples, particularly of the central nervous system (CNS), has proven challenging due to the restricted amounts of material and the presence of fatty tissue components. In order to address this, the described protocol is specifically optimized for use with minimal amount of CNS material, as demonstrated by the use of single mouse spinal cord and brain. Briefly, CNS tissues are extracted and translating ribosomes are immobilized on mRNAs with cycloheximide. Myelin flotation is then performed to remove lipid rich components. Fractionation is performed on a sucrose gradient where mRNAs are separated according to their ribosomal loading. Isolated fractions are suitable for a range of downstream assays, including new genome wide assay technologies.

In vivo Interrogation of Central Nervous System Translatome by Polyribosome Fractionation

This protocol illustrates essential modifications of polyribosome fractionation in order to study the translatome of in vivo CNS samples. It allows global assessment of translation and transcription regulation through the isolation and comparison of total RNA to ribosome bound RNA fractions.

En Interrogatorio vivo del Sistema Nervioso Central Translatome por Polyribosome Fraccionamiento

Multiple processes are involved in gene expression including transcription, translation and stability of mRNAs and proteins. Each of these steps are ...

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing.

In vivo Optogenetic Stimulation of the Rodent Central Nervous System

Optogenetics has become a powerful tool for use in behavioral neuroscience experiments. This protocol offers a step-by-step guide to the design and set-up of laser systems, and provides a full protocol for carrying out multiple and simultaneous in vivo optogenetic stimulations compatible with most rodent behavioral testing paradigms.

In vivo optogenético la estimulación del sistema nervioso central de roedores

The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution ...

Optical Clearing of the Mouse Central Nervous System Using Passive CLARITY

Traditionally, tissue visualization has required that the tissue of interest be serially sectioned and imaged, subjecting each tissue section to unique non-linear deformations, dramatically hampering one's ability to evaluate cellular morphology, distribution and connectivity in the central nervous system (CNS). However, optical clearing techniques are changing the way tissues are visualized. These approaches permit one to probe deeply into intact organ preparations, providing tremendous insight into the structural organization of tissues in health and disease. Techniques such as Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging-compatible Tissue-hYdrogel (CLARITY) achieve this goal by providing a matrix that binds important biomolecules while permitting light-scattering lipids to freely diffuse out. Lipid removal, followed by refractive index matching, renders the tissue transparent and readily imaged in 3 dimensions (3D). Nevertheless, the electrophoretic tissue clearing (ETC) used in the original CLARITY protocol can be challenging to implement successfully and the use of a proprietary refraction index matching solution makes it expensive to use the technique routinely. This report demonstrates the implementation of a simple and inexpensive optical clearing protocol that combines passive CLARITY for improved tissue integrity and 2,2&#8242;-thiodiethanol (TDE), a previously described refractive index matching solution.

Optical clearing techniques are revolutionizing the way tissues are visualized. In this report we describe modifications of the original Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging-compatible Tissue-hYdrogel (CLARITY) protocol that yields more consistent and less expensive results.

Clearing óptico del sistema nervioso central del ratón Utilizando CLARITY pasiva

Traditionally, tissue visualization has required that the tissue of interest be serially sectioned and imaged, subjecting each tissue section to unique ...

El marcaje de células individuales en el Sistema Nervioso Central de

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