Nos gustaría reconocer Sean Whelan para obtener ayuda con el rescate de las variantes recombinantes VSV y Didem Goz y Chrenek Ryan de asistencia técnica. Este trabajo fue financiado por el HHMI (CLC), y # NS068012-01 (KTB).

<ol>
	<li>Wickersham, I. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monosynaptic+restriction+of+transsynaptic+tracing+from+single,+genetically+targeted+neurons.">Monosynaptic restriction of transsynaptic tracing from single, genetically targeted neurons.</a> Neuron. 53, 639-647 (2007).</li><li>Marshel, J. H., Mori, T., Nielsen, K. J., Callaway, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+single+neuronal+networks+for+gene+expression+and+cell+labeling+in+vivo.">Targeting single neuronal networks for gene expression and cell labeling in vivo.</a> Neuron. 67, 562-574 (2010).</li><li>Wall, N. R., Wickersham, I. R., Cetin, A., De La Parra, M., Callaway, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monosynaptic+circuit+tracing+in+vivo+through+Cre-dependent+targeting+and+complementation+of+modified+rabies+virus.">Monosynaptic circuit tracing in vivo through Cre-dependent targeting and complementation of modified rabies virus.</a> Proc. Natl. Acad. Sci. U.S.A. 107, 21848-21853 (2010).</li><li>Wickersham, I. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monosynaptic+restriction+of+transsynaptic+tracing+from+single,+genetically+targeted+neurons.">Monosynaptic restriction of transsynaptic tracing from single, genetically targeted neurons.</a> Neuron. 53, 639-647 (2007).</li><li>Yonehara, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatially+asymmetric+reorganization+of+inhibition+establishes+a+motion-sensitive+circuit.">Spatially asymmetric reorganization of inhibition establishes a motion-sensitive circuit.</a> Nature. 469, 407-410 (2011).</li><li>Stepien, A. E., Tripodi, M., Arber, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monosynaptic+rabies+virus+reveals+premotor+network+organization+and+synaptic+specificity+of+cholinergic+partition+cells.">Monosynaptic rabies virus reveals premotor network organization and synaptic specificity of cholinergic partition cells.</a> Neuron. 68, 456-472 (2010).</li><li>Beier, K. T., Samson, M. E. S., Matsuda, T., Cepko, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conditional+expression+of+the+TVA+receptor+allows+clonal+analysis+of+descendents+from+Cre-expressing+progenitor+cells.">Conditional expression of the TVA receptor allows clonal analysis of descendents from Cre-expressing progenitor cells.</a> Dev. Biol. 353, 309-320 (2011).</li><li>Seidler, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Cre-loxP-based+mouse+model+for+conditional+somatic+gene+expression+and+knockdown+in+vivo+by+using+avian+retroviral+vectors.">A Cre-loxP-based mouse model for conditional somatic gene expression and knockdown in vivo by using avian retroviral vectors.</a> Proc. Natl. Acad. Sci. U.S.A. 105, 10137-10142 (2008).</li><li>Beier, K. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anterograde+or+retrograde+transsynaptic+labeling+of+CNS+neurons+with+vesicular+stomatitis+virus+vectors.">Anterograde or retrograde transsynaptic labeling of CNS neurons with vesicular stomatitis virus vectors.</a> Proc. Natl. Acad. Sci. U.S.A. 108, 15414-15419 (2011).</li><li>Whelan, S. P., Ball, L. A., Barr, J. N., Wertz, G. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+recovery+of+infectious+vesicular+stomatitis+virus+entirely+from+cDNA+clones.">Efficient recovery of infectious vesicular stomatitis virus entirely from cDNA clones.</a> Proc. Natl. Acad. Sci. U.S.A. 92, 8388-8392 (1995).</li><li>Fuerst, T. R., Niles, E. G., Studier, F. W., Moss, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eukaryotic+Transient-Expression+System+Based+on+Recombinant+Vaccinia+Virus+That+Synthesizes+Bacteriophage+T7+RNA+Polymerase.">Eukaryotic Transient-Expression System Based on Recombinant Vaccinia Virus That Synthesizes Bacteriophage T7 RNA Polymerase.</a> PNAS. 83, 8122-8126 (1986).</li><li>Young, J. A., Bates, P., Varmus, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+a+chicken+gene+that+confers+susceptibility+to+infection+by+subgroup+A+avian+leukosis+and+sarcoma+viruses.">Isolation of a chicken gene that confers susceptibility to infection by subgroup A avian leukosis and sarcoma viruses.</a> J. Virol. 67, 1811-1816 (1993).</li><li>Madisen, 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+robust+and+high-throughput+Cre+reporting+and+characterization+system+for+the+whole+mouse+brain.">A robust and high-throughput Cre reporting and characterization system for the whole mouse brain.</a> Nat Neurosci. 13, 133-140 (2010).</li><li>Franklin, K., Paxinos, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Mouse Brain in Stereotaxic Coordinates. , (1997).</li><li>van den Pol, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Viral+strategies+for+studying+the+brain,+including+a+replication-restricted+self-amplifying+delta-G+vesicular+stomatis+virus+that+rapidly+expresses+transgenes+in+brain+and+can+generate+a+multicolor+golgi-like+expression.">Viral strategies for studying the brain, including a replication-restricted self-amplifying delta-G vesicular stomatis virus that rapidly expresses transgenes in brain and can generate a multicolor golgi-like expression.</a> J. Comp. Neurol. 516, 456-481 (2009).</li></ol>

No hay conflictos de interés declarado.

Uso de virus para estudiar circuitos neuronales es un método de rendimiento relativamente alto de analizar neuronas conectadas. Sin embargo, generar tanto VSV y viriones RABV no es trivial. Aunque el protocolo enumerados anteriormente para el virus de rescate a partir de ADNc se proporciona, todavía es un evento de baja probabilidad. Los niveles de cada uno de los N, P, L y plásmidos necesitan ser ajustado con precisión, ya que muchos ensayos y replica necesita hacer para asegurar rescate viral. La formación de la ...

<table border="1">
	<tbody>
		<tr>
			<td>Reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Tissue Culture</td>
		</tr>
		<tr>
			<td>Baby Hamster Kidney (BSRT7) cells</td>
			<td>available upon request</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>vaccinia (vTF7-3)</td>
			<td>available upon request</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>pN, pP, pl plasmids</td>
			<td>available upon request</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Calcium Chloride</td>
			<td>Sigma</td>
			<td>C1016</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Magnesium Chloride</td>
			<td>Sigma</td>
			<td>M8266</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>HEK 293T cells</td>
			<td>Open Biosystems</td>
			<td>HCL4517</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>60 mm TC-Treated Culture Dish</td>
			<td>Corning</td>
			<td>430166</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>75 cm2 Rectangular Canted Neck Cell Culture Flask with Vent Cap</td>
			<td>Corning</td>
			<td>430641</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Media : DMEM (Dulbecco's Modified Eagle Medium)</td>
			<td>Invitrogen</td>
			<td>12491-015</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>1 M HEPES pH 7.4</td>
			<td>Gibo</td>
			<td>15630-080</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>FBS: Fetal Bovine Serum</td>
			<td>Gibco</td>
			<td>10437-028</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>PKS</td>
			<td>Invitrogen</td>
			<td>15140-163</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Lipofectamine 2,000 Transfection Reagent</td>
			<td>Invitrogen</td>
			<td>11668-019</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Syringe: 5 ml Luer-Lock syringe</td>
			<td>Sigma</td>
			<td>Z248010-1PAK</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Syringe Filters</td>
			<td>Nalgene</td>
			<td>190-2520</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>PEI: High Potency Linear PEI</td>
			<td>Polysciences</td>
			<td>23966</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Viral Centrifugation</td>
		</tr>
		<tr>
			<td>Corning 150 ml Tube Top Vacuum Filter System, 0.45 &mu;m Pore</td>
			<td>Corning</td>
			<td>430314</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Thinwall, Ultra-Clear, 38.5 ml, 25 x 89 mm ultracentrifuge tubes</td>
			<td>Beckman-Coulter</td>
			<td>344058</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Beckman-Coulter</td>
			<td>optima XL-80K</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>SW28 Ultracentrifuge rotor</td>
			<td>Beckman-Coulter</td>
			<td>342207</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Mouse Injection</td>
		</tr>
		<tr>
			<td>Capillary micropipets</td>
			<td>Drummond</td>
			<td>5-000-2005</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Stereotax</td>
			<td>Narishige</td>
			<td>SR-5M</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Micromanipulator</td>
			<td>Narishige</td>
			<td>SM-15</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Ump injector</td>
			<td>World Precision Instruments</td>
			<td>Sys-Micro4</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Four channel microcontroller</td>
			<td>World Precision Instruments</td>
			<td>UMP3</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>M.TXB Bench Motor with C.EMX-1 Dial Control, 115 Volt</td>
			<td>Foredom</td>
			<td>M.TXB-EM</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>H.10 Handpiece, Quick Change</td>
			<td>Foredom</td>
			<td>H.10</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Step Drill, 0.5 mm</td>
			<td>Foredom</td>
			<td>A-58005P</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Microelectrode holder</td>
			<td>World Precision Instruments</td>
			<td>MEH2S</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Henry Schein</td>
			<td>995-2949</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Henry Schein</td>
			<td>4015809TV</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Henry Schein</td>
			<td>1118217</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>1 ml syringe</td>
			<td>Becton-Dickinson</td>
			<td>309628</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>30 gauge injection needle</td>
			<td>Becton-Dickinson</td>
			<td>305106</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Protective Ophthalmic Ointment</td>
			<td>Doctors Foster and Smith</td>
			<td>9N-014748</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Sigma</td>
			<td>493511</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Iodine</td>
			<td>Sigma</td>
			<td>PVP1</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Surgery and Dissection tools</td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Fine Science Tools</td>
			<td>91402-12</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Standard Forceps</td>
			<td>Fine Science Tools</td>
			<td>11000-12</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Fine Forceps</td>
			<td>Fine Science Tools</td>
			<td>11255-20</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Vannas spring scissors</td>
			<td>Fine Science Tools</td>
			<td>15000-00</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Scalpel handle</td>
			<td>Fine Science Tools</td>
			<td>10003-12</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Scalpel blades</td>
			<td>Fine Science Tools</td>
			<td>10015-00</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Sutures</td>
			<td>Robbins Instruments</td>
			<td>20.SK640</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Dissection and antibody staining</td>
		</tr>
		<tr>
			<td>paraformaldehyde</td>
			<td>Sigma</td>
			<td>P6148</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline</td>
			<td>Sigma</td>
			<td>P4417</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma</td>
			<td>T9284</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Donkey Serum</td>
			<td>Jackson Immunoresearch</td>
			<td>017-000-121</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Antibodies</td>
		</tr>
		<tr>
			<td>Antibodies</td>
			<td>millipore</td>
			<td>AB144P</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Anti-gfp</td>
			<td>Abcam</td>
			<td>ab13970</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Donkey anti-chicken Dylight 488</td>
			<td>Jackson immunoresearch</td>
			<td>703-545-155</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Donkey anti-chicken Alexa Fluor 647</td>
			<td>Jackson immunoresearch</td>
			<td>705-605-147</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Invitrogen</td>
			<td>D1306</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>Tissue mounting</td>
		</tr>
		<tr>
			<td>Superfrost plus microscope slides</td>
			<td>Fisher</td>
			<td>12-550-100</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Cover glass 22 x 22, 0 thickness</td>
			<td>Electron Microscopy Sciences</td>
			<td>72198-10</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Silicone elastomer</td>
			<td>Rogers Corp</td>
			<td>HT-6220</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Clear nail polish</td>
			<td>Electron Microscopy Sciences</td>
			<td>72180</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Prolong Gold antifade reagent</td>
			<td>Invitrogen</td>
			<td>P36930</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

viral tracing of genetically defined neural circuitry

Los métodos clásicos para el estudio de los circuitos neuronales están rendimiento bastante bajo. Transsynaptic virus, particularmente la pseudorrabia (PRV) y virus de la rabia (RABV), y más recientemente virus de la estomatitis vesicular (VSV), para el estudio de circuitos, es cada vez más popular. Estos métodos de rendimiento más altos utilizan virus que transmiten entre las neuronas, ya sea en la dirección anterógrada o retrógrada. Recientemente, un RABV modificado para monosináptico retrógrada rastreo fue desarrollado. (Figura 1A). En este método, la glicoproteína (G) de genes se elimina del genoma viral, y reabastecidos sólo en las neuronas específicas. Especificidad infección se logra mediante la sustitución de una G quimérico, formado por el dominio extracelular de la glicoproteína ASLV-A y el dominio citoplásmico de la RABV-G (A / RG), para el normal RABV-G 1. Este G quimérica específicamente infecta las células que expresan el receptor TVA 1. El gen que codifica TVA puede sido delivered por diversos métodos 2-8. Tras RABV-G infección de una neurona TVA-expresando, el RABV puede transmitir a otras neuronas, conectadas sinápticamente en una dirección retrógrada por la naturaleza de su propio G que fue cosuministrado con el receptor de TVA. Esta técnica etiqueta un número relativamente grande de entradas (5-10%) 2 en un tipo celular definido, proporcionando un muestreo de todas las entradas en un tipo de célula de arranque definido. Recientemente hemos modificado esta técnica a utilizar VSV como un trazador transsynaptic 9. VSV tiene varias ventajas, incluyendo la rapidez de la expresión génica. A continuación detallamos un nuevo sistema de rastreo viral utilizando útiles para sondear microcircuitos con mayor resolución VSV. Mientras que las estrategias original publicado por Wickersham et al. 4 y Beier et al. 9 permiso de etiquetado de cualquier neuronas que se proyectan hacia inicialmente infectado-TVA-expresando células, aquí VSV fue diseñado para transmitir sólo a TVCélulas que expresan A-(Figura 1B). El virus es primero pseudotyped con RABV-G para permitir la infección de aguas abajo de las neuronas que expresan TVA neuronas. Después de infectar esta primera población de células, el virus liberado sólo pueden infectar células que expresan TVA. Debido a la propagación viral transsynaptic se limita a las células que expresan TVA, la presencia de ausencia de la conectividad de los tipos de células definidos pueden ser explorados con alta resolución. Un diagrama de flujo experimental de estos experimentos se muestra en la Figura 2. Aquí se muestra un circuito de modelo, el de la dirección de selectividad en la retina del ratón. Se examina la conectividad de las células amacrinas starburst (ZEC) a las células ganglionares de la retina (CGR).

Watch this Scientific Journal Video about Viral Tracing of Genetically Defined Neural Circuitry at JoVE.com

Viral Tracing of Genetically Defined Neural Circuitry

Un método de rastreo de neuronas conectadas sinápticamente se describe. Usamos especificidad TVA de una célula de aguas arriba para probar si una población celular de interés recibe la entrada sináptica de tipos de células genéticamente definidos.

Trazado de Circuitos Viral genéticamente definidos Neural

Classical methods for studying neuronal circuits are fairly low throughput. Transsynaptic viruses, particularly the pseudorabies (PRV) and rabies virus ...

viral-tracing-of-genetically-defined-neural-circuitry

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Neuroscience

18.4K vistas.  Harvard Medical School. Un método de rastreo de neuronas conectadas sinápticamente se describe. Usamos especificidad TVA de una célula de aguas arriba para probar si una población celular de interés recibe la entrada sináptica de tipos de células genéticamente definidos.

Video: Viral Tracing of Genetically Defined Neural Circuitry

Membrane Potentials, Synaptic Responses, Neuronal Circuitry, Neuromodulation and Muscle Histology Using the Crayfish: Student Laboratory Exercises

The purpose of this report is to help develop an understanding of the effects caused by ion gradients across a biological membrane. Two aspects that influence a cell's membrane potential and which we address in these experiments are: (1) Ion concentration of K+ on the outside of the membrane, and (2) the permeability of the membrane to specific ions. The crayfish abdominal extensor muscles are in groupings with some being tonic (slow) and others phasic (fast) in their biochemical and physiological phenotypes, as well as in their structure; the motor neurons that innervate these muscles are correspondingly different in functional characteristics. We use these muscles as well as the superficial, tonic abdominal flexor muscle to demonstrate properties in synaptic transmission. In addition, we introduce a sensory-CNS-motor neuron-muscle circuit to demonstrate the effect of cuticular sensory stimulation as well as the influence of neuromodulators on certain aspects of the circuit. With the techniques obtained in this exercise, one can begin to answer many questions remaining in other experimental preparations as well as in physiological applications related to medicine and health. We have demonstrated the usefulness of model invertebrate preparations to address fundamental questions pertinent to all animals.

The experiments demonstrate an easy approach for students to gain experience in examining muscle structure, synaptic responses, the effects of ion gradients and permeability on membrane potentials. Also, a sensory-CNS-motor-muscle circuit is presented to show a means to test effects of compounds on a neuronal circuit.

Los potenciales de membrana, las respuestas sinápticas, circuitos neuronales, neuromodulación y la histología muscular utilizando el cangrejo de río: Los ejercicios de laboratorio para estudiantes

The purpose of this report is to help develop an understanding of the effects caused by ion gradients across a biological membrane. Two aspects that ...

Investigación

Neurociencias

Physiological, Morphological and Neurochemical Characterization of Neurons Modulated by Movement

The role of individual neurons and their function in neuronal circuits is fundamental to understanding the neuronal mechanisms of sensory and motor functions. Most investigations of sensorimotor mechanisms rely on either examination of neurons while an animal is static1,2 or record extracellular neuronal activity during a movement.3,4 While these studies have provided the fundamental background for sensorimotor function, they either do not evaluate functional information which occurs during a movement or are limited in their ability to fully characterize the anatomy, physiology and neurochemical phenotype of the neuron. A technique is shown here which allows extensive characterization of individual neurons during an in vivo movement. This technique can be used not only to study primary afferent neurons but also to characterize motoneurons and sensorimotor interneurons. Initially the response of a single neuron is recorded using electrophysiological methods during various movements of the mandible followed by determination of the receptive field for the neuron. A neuronal tracer is then intracellularly injected into the neuron and the brain is processed so that the neuron can be visualized with light, electron or confocal microscopy (Fig. 1). The detailed morphology of the characterized neuron is then reconstructed so that neuronal morphology can be correlated with the physiological response of the neuron (Figs. 2,3). In this communication important key details and tips for successful implementation of this technique are provided. Valuable additional information can be determined for the neuron under study by combining this method with other techniques. Retrograde neuronal labeling can be used to determine neurons with which the labeled neuron synapses; thus allowing detailed determination of neuronal circuitry. Immunocytochemistry can be combined with this method to examine neurotransmitters within the labeled neuron and to determine the chemical phenotypes of neurons with which the labeled neuron synapses. The labeled neuron can also be processed for electron microscopy to determine the ultrastructural features and microcircuitry of the labeled neuron. Overall this technique is a powerful method to thoroughly characterize neurons during in vivo movement thus allowing substantial insight into the role of the neuron in sensorimotor function.

A technique is described to quantify the in vivo physiological response of mammalian neurons during movement and correlate the physiology of the neuron with neuronal morphology, neurochemical phenotype and synaptic microcircuitry.

Caracterización fisiológicas, morfológicas y neuroquímicas de las neuronas modulada por el Movimiento

The role of individual neurons and their function in neuronal circuits is fundamental to understanding the neuronal mechanisms of sensory and motor ...

Detection of Microregional Hypoxia in Mouse Cerebral Cortex by Two-photon Imaging of Endogenous NADH Fluorescence

The brain's ability to function at high levels of metabolic demand depends on continuous oxygen supply through blood flow and tissue oxygen diffusion. Here we present a visualized experimental and methodological protocol to directly visualize microregional tissue hypoxia and to infer perivascular oxygen gradients in the mouse cortex. It is based on the non-linear relationship between nicotinamide adenine dinucleotide (NADH) endogenous fluorescence intensity and oxygen partial pressure in the tissue, where observed tissue NADH fluorescence abruptly increases at tissue oxygen levels below 10 mmHg1. We use two-photon excitation at 740 nm which allows for concurrent excitation of intrinsic NADH tissue fluorescence and blood plasma contrasted with Texas-Red dextran. The advantages of this method over existing approaches include the following: it takes advantage of an intrinsic tissue signal and can be performed using standard two-photon in vivo imaging equipment; it permits continuous monitoring in the whole field of view with a depth resolution of ~50 &mu;m. We demonstrate that brain tissue areas furthest from cerebral blood vessels correspond to vulnerable watershed areas which are the first to become functionally hypoxic following a decline in vascular oxygen supply. This method allows one to image microregional cortical oxygenation and is therefore useful for examining the role of inadequate or restricted tissue oxygen supply in neurovascular diseases and stroke.

Here we describe a method to directly visualize microregional tissue hypoxia in the mouse cortex in vivo. It is based on concurrent two-photon imaging of nicotinamide adenine dinucleotide (NADH) and the cortical microcirculation. This method is useful for high resolution analysis of tissue oxygen supply.

La detección de la hipoxia Microrregional en corteza cerebral de ratón por la imagen de dos fotones de fluorescencia endógena NADH

The brain's ability to function at high levels of metabolic demand depends on continuous oxygen supply through blood flow and tissue oxygen diffusion. ...

Reproducible Mouse Sciatic Nerve Crush and Subsequent Assessment of Regeneration by Whole Mount Muscle Analysis

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative response mounted by PNS neurons thereby possibly illuminating the failures of CNS regeneration1. Sciatic nerve crush (axonotmesis) is one of the most common models of peripheral nerve injury in rodents2. Crushing interrupts all axons but Schwann cell basal laminae are preserved so that regeneration is optimal3,4. This allows the investigator to study precisely the ability of a growing axon to interact with both the Schwann cell and basal laminae4. Rats have generally been the preferred animal models for experimental nerve crush. They are widely available and their lesioned sciatic nerve provides a reasonable approximation of human nerve lesions5,4. Though smaller in size than rat nerve, the mouse nerve has many similar qualities. Most importantly though, mouse models are increasingly valuable because of the wide availability of transgenic lines now allows for a detailed dissection of the individual molecules critical for nerve regeneration6, 7. Prior investigators have used multiple methods to produce a nerve crush or injury including simple angled forceps, chilled forceps, hemostatic forceps, vascular clamps, and investigator-designed clamps8,9,10,11,12. Investigators have also used various methods of marking the injury site including suture, carbon particles and fluorescent beads13,14,1. We describe our method to obtain a reproducibly complete sciatic nerve crush with accurate and persistent marking of the crush-site using a fine hemostatic forceps and subsequent carbon crush-site marking. As part of our description of the sciatic nerve crush procedure we have also included a relatively simple method of muscle whole mount we use to subsequently quantify regeneration.

In this report we describe a method to crush mouse sciatic nerve. This method uses readily available hemostatic forceps and easily and reproducibly produces complete sciatic nerve crush. In addition, we describe a method to prepare muscle whole mounts suitable for analysis of nerve regeneration after sciatic nerve crush.

Ratón reproducible aplastamiento del nervio ciático y posterior evaluación de la regeneración mediante el análisis de músculo entero Monte

Regeneration in the peripheral nervous system (PNS) is widely studied both for its relevance to human disease and to understand the robust regenerative ...

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 ...

Modeling Astrocytoma Pathogenesis In Vitro and In Vivo Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice

Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease pathogenesis and their utility for preclinical drug development. In order to design a better model system for these applications, phenotypically wild-type cortical astrocytes and neural stem cells (NSC) from conditional, genetically engineered mice (GEM) that harbor various combinations of floxed oncogenic alleles were harvested and grown in culture. Genetic recombination was induced in vitro using adenoviral Cre-mediated recombination, resulting in expression of mutated oncogenes and deletion of tumor suppressor genes. The phenotypic consequences of these mutations were defined by measuring proliferation, transformation, and drug response in vitro. Orthotopic allograft models, whereby transformed cells are stereotactically injected into the brains of immune-competent, syngeneic littermates, were developed to define the role of oncogenic mutations and cell type on tumorigenesis in vivo. Unlike most established human glioblastoma cell line xenografts, injection of transformed GEM-derived cortical astrocytes into the brains of immune-competent littermates produced astrocytomas, including the most aggressive subtype, glioblastoma, that recapitulated the histopathological hallmarks of human astrocytomas, including diffuse invasion of normal brain parenchyma. Bioluminescence imaging of orthotopic allografts from transformed astrocytes engineered to express luciferase was utilized to monitor in vivo tumor growth over time. Thus, astrocytoma models using astrocytes and NSC harvested from GEM with conditional oncogenic alleles provide an integrated system to study the genetics and cell biology of astrocytoma pathogenesis in vitro and in vivo and may be useful in preclinical drug development for these devastating diseases.

Modeling Astrocytoma Pathogenesis In Vitro and In Vivo Using Cortical Astrocytes or Neural Stem Cells from Conditional, Genetically Engineered Mice

Phenotypically wild-type astrocytes and neural stem cells harvested from mice engineered with floxed, conditional oncogenic alleles and transformed via viral Cre-mediated recombination can be used to model astrocytoma pathogenesis in vitro and in vivo by orthotopic injection of transformed cells into brains of syngeneic, immune-competent littermates.

Modelado astrocitoma Patogénesis<em&gt; In Vitro</em&gt; Y<em&gt; En Vivo</em&gt; Uso cortical astrocitos o células troncales nerviosas de ratones condicionales, Genéticamente Manipulados

Current astrocytoma models are limited in their ability to define the roles of oncogenic mutations in specific brain cell types during disease ...

A Lateralized Odor Learning Model in Neonatal Rats for Dissecting Neural Circuitry Underpinning Memory Formation

Rat pups during a critical postnatal period (&#8804; 10 days) readily form a preference for an odor that is associated with stimuli mimicking maternal care. Such a preference memory can last from hours, to days, even life-long, depending on training parameters. Early odor preference learning provides us with a model in which the critical changes for a natural form of learning occur in the olfactory circuitry. An additional feature that makes it a powerful tool for the analysis of memory processes is that early odor preference learning can be lateralized via single naris occlusion within the critical period. This is due to the lack of mature anterior commissural connections of the olfactory hemispheres at this early age. This work outlines behavioral protocols for lateralized odor learning using nose plugs. Acute, reversible naris occlusion minimizes tissue and neuronal damages associated with long-term occlusion and more aggressive methods such as cauterization. The lateralized odor learning model permits within-animal comparison, therefore greatly reducing variance compared to between-animal designs. This method has been used successfully to probe the circuit changes in the olfactory system produced by training. Future directions include exploring molecular underpinnings of odor memory using this lateralized learning model; and correlating physiological change with memory strength and durations.

This protocol introduces lateralized early odor preference learning in rats using acute single naris occlusion. Lateralized learning permits the examination of behavioral outcomes and underpinning biological mechanisms within the same animals, reducing variance induced by between-animal designs. This protocol can be used to investigate molecular mechanisms underpinning early odor learning.

Un Modelo de Aprendizaje lateralizado de Olor en ratas recién nacidas para disecar Formación Neural Circuito Recalces Memoria

Rat pups during a critical postnatal period (&#8804; 10 days) readily form a preference for an odor that is associated with stimuli mimicking maternal ...

Conditional Genetic Transsynaptic Tracing in the Embryonic Mouse Brain

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits during embryonic maturation of the brain however is technically challenging because most transsynaptic tracing methods developed to date depend on stereotaxic tracer injection. To overcome this problem, we developed a binary genetic strategy for conditional genetic transsynaptic tracing in the mouse brain. Towards this end we generated two complementary knock-in mouse strains to selectively express the bidirectional transsynaptic tracer barley lectin (BL) and the retrograde transsynaptic tracer Tetanus Toxin fragment C from the ROSA26 locus after Cre-mediated recombination. Cell-specific tracer production in these mice is genetically encoded and does not depend on mechanical tracer injection. Therefore our experimental approach is suitable to study neural circuit formation in the embryonic murine brain. Furthermore, because tracer transfer across synapses depends on synaptic activity, these mouse strains can be used to analyze the communication between genetically defined neuronal populations during brain development at a single cell resolution. Here we provide a detailed protocol for transsynaptic tracing in mouse embryos using the novel recombinant ROSA26 alleles. We have utilized this experimental technique in order to delineate the neural circuitry underlying maturation of the reproductive axis in the developing female mouse brain.

Capitalizing on a binary genetic strategy we provide a detailed protocol for neural circuit tracing in mice that express complementary transsynaptic tracers after Cre-mediated recombination. Because cell-specific tracer production is genetically encoded, our experimental approach is suitable to study the formation and maturation of neural circuitry during murine embryonic brain development at a single cell resolution.

Condicional transsynaptic genética Seguimiento en el cerebro de embriones de ratón

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits ...

Laser-guided Neuronal Tracing In Brain Explants

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake through electroporation in brain explants with targeted laser illumination and matching filter goggles during the procedure. The described technique of in vitro electroporation by itself yields relatively good visual control for targetting certain areas of the brain. By combining it with laser excitation of fluorescent genetic markers and their read-out through band-passing filter goggles, which can pick up the emissions of the genetically labeled cells/nuclei and the fluorescent tracing dye, a researcher can substantially increase the accuracy of injections by finding the area of interest and controlling for the dye-spread/uptake in the injection area much more efficiently. In addition, the laser illumination technique allows to study the functionality of a given neurocircuit by providing information about the type of neurons projecting to a certain area in cases where the GFP expression is linked to the type of transmitter expressed by a subpopulation of neurons.

We describe a technique to label neurons and their processes via anterograde or retrograde tracer injections into brain nuclei using an in vitro preparation. We modified an existing method of in vitro tracer electroporation by taking advantage of fluorescently labeled mouse mutants and basic optical equipment in order to increase labeling accuracy.

Neuronal Tracing en explantes cerebrales guiadas por láser

We present a technique which combines an in vitro tracer injection protocol, which uses a series of electrical and pressure pulses to increase dye uptake ...

Time-dependent Increase in the Network Response to the Stimulation of Neuronal Cell Cultures on Micro-electrode Arrays

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network dynamics in neuronal cultures. In contrast with more traditional methods, such as patch-clamping, which can only record activity from a single cell, MEAs can record simultaneously from multiple sites in a network, without requiring the arduous task of placing each electrode individually. Moreover, numerous control and stimulation configurations can be easily applied within the same experimental setup, allowing for a broad range of dynamics to be explored. One of the key dynamics of interest in these in vitro studies has been the extent to which cultured networks display properties indicative of learning. Mouse neuronal cells cultured on MEAs display an increase in response following training induced by electrical stimulation. This protocol demonstrates how to culture neuronal cells on MEAs; successfully record from over 95% of the plated dishes; establish a protocol to train the networks to respond to patterns of stimulation; and sort, plot, and interpret the results from such experiments. The use of a proprietary system for stimulating and recording neuronal cultures is demonstrated. Software packages are also used to sort neuronal units. A custom-designed graphical user interface is used to visualize post-stimulus time histograms, inter-burst intervals, and burst duration, as well as to compare the cellular response to stimulation before and after a training protocol. Finally, representative results and future directions of this research effort are discussed.

Mouse neuronal cells cultured on multi-electrode arrays display an increase in response following electrical stimulation. This protocol demonstrates how to culture neurons, how to record activity, and how to establish a protocol to train the networks to respond to patterns of stimulation.

Incremento dependiente del tiempo en la respuesta de la red a la estimulación de cultivos de células neuronales en matrices de microelectrodos

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network ...