Vogliamo ringraziare Arumae Urmas per la condivisione di un protocollo di collagene e Jutta Fey e Ursula Hinz per un&#39;eccellente assistenza tecnica. Inoltre vogliamo ringraziare Christian F. Ackermann, Ulrike Engel e la Nikon Imaging Center presso l&#39;Università di Heidelberg e anche per Joachim Kirsch aiuto gentile per il Shoting video. Il lavoro è stato parzialmente finanziato attraverso la Deutsche Forschungsgemeinschaft (SFB 592).

1. Preparazione del gel di collagene <ol><li> Preparare un mezzo magazzino, contenente 455 microlitri MEM 10x, 112 microlitri NaHCO 7,5% 3, 50 microlitri glutammina e NaOH. La concentrazione e la quantità di NaOH dipende dalla coda di topo preparazione collagene (vedere 1.2), il volume finale del mezzo magazzino essendo 1.000 microlitri. </li><li> Preparare coda di topo collagene secondo Ebendal (1). Conservare la soluzione di collagene a 4 ° C. Una degradazione del collagene soluzione non poteva essere osservato. Dopo la preparazione di un nuovo gruppo, valutare la concentrazione di NaOH necessaria per il mezzo stock (vedere 1.1). Utilizzare il pH del mezzo indicatore per la titolazione della quantità e concentrazione di NaOH. 800 microlitri acido coda di topo collagene deve girare una tonalità di rosso quando miscelato con 210 ml di mezzo di brodo. Se la concentrazione di NaOH è troppo bassa la soluzione di collagene diventa giallo, per l&#39;indicatore di pH del mezzo. Aggiungi il collagene al mezzo e mescolare senza prodottiucing bolle. Eseguire questi passaggi su ghiaccio. La polimerizzazione si verifica entro 2 ore dopo la soluzione di collagene e il mezzo magazzino sono stati mescolati e la nuova soluzione viene incubata a 37 ° C. Prova questo prima di iniziare un esperimento. 1.3) Mescolare 800 ml di soluzione di collagene con pl 210 di media stock (vedi 1.2). Posto 100 pl di questa soluzione in pozzetti di una slitta 8 camera bene. Incubare i vetrini a 37 ° C, 5% di CO 2 e umido in una cella incubatore. Preparare i gel di collagene sotto un banco di coltura cellulare e condizioni sterili. Il collagene gelatinizes entro 2 ore. </li></ol> 2. Dissezione di SCGS embrionali <ol><li> Harvest embrioni di topo gravide tempo (E16-18) dall&#39;utero e tenerli in PBS fino a nuovo necessario. </li><li> Staccare un embrione dalla membrana amniotica. Decapitare il caudale dell&#39;embrione del livello clavicolare. Fissare la testa su un piatto fondo di silicio con &quot;insetto-aghi&quot;. Il lato ventrale della testa deve affrontare a voi und si deve vedere la regione sottomandibolare. Il fissaggio per un facile preparazione. </li><li> Rimuovere la pelle della regione sottomandibolare destra e sinistra e con essa la sottocutaneo tessuto connettivo. </li><li> Rimuovere le ghiandole salivari sottomandibolari dalla loro posizione per cancellare la vista sulla ioide, i muscoli infrahyoidal e il muscolo sternocleidomastoideo. </li><li> Rimuovere questi muscoli con attenzione per eliminare la vista sulla laringe e della trachea. Rimuovere la trachea e la laringe. Le arterie carotidi sono quindi visibili da entrambi i lati sui muscoli prevertebrali. Il SCG si trova nella biforcazione delle arterie carotidee e ha una forma ovale. Rimuovere con attenzione i gangli e metterli in PBS. Rimuovere i gangli delicatamente dagli strumenti di dissezione se sono aderiscano. E &#39;vantaggioso utilizzare pinze nonché un porta aghi montato con un &quot;ago insetto&quot; per la rimozione SCG. </li><li> Una volta in PBS, memorizzare i gangli a temperatura ambiente in PBS fino sezionato enougangli gh. Quindi pulire i gangli dai vasi sanguigni e tessuto connettivo. Eseguire la dissezione SCG e pulizia sotto un microscopio da dissezione posta sotto un banco di flusso laminare. </li><li> Infine, posizionare i gangli espiantato sui gel di collagene gelatinizzati con l&#39;aiuto della siringa aghi montati su una siringa per facilitarne la movimentazione. </li><li> Incubare le espianti SCG sul collagene gelificato in un incubatore per colture cellulari a 37 ° C, con il 5% di CO 2 e condizioni umide. </li></ol> 3. Trattamento di espianti SCG <ol><li> Dopo 1-2 ore di incubazione, coprire il collagene espianto SCG contenente terreno con 100 microlitri Neurobasal coltura cellulare contenente B27 supplemento, glutammina e antibiotici. Ora i pozzetti dei vetrini camera contiene un volume di 200 pl (100 microlitri gel e 100 microlitri media). Aggiungere altri 200 pl di mezzo, ma ora contenenti NGF (60 ng / ml) per facilitare la crescita assonale. Di conseguenza la concentrazione finale NGF è di 30 ng / ml. </li><li><ol class="lalpha"><li> Per studiare l&#39;insorgenza di SC migrazione, aggiungere ulteriori fattori direttamente al giorno in vitro 0 (DIV0). Sciogliere i fattori a medio NGF, contenenti, in doppia concentrazione necessaria (2). </li><li> Al fine di analizzare l&#39;impatto sulla SC, che ha già iniziato la migrazione lungo gli assoni, aggiungere ulteriori fattori a DIV3 fino DIV4 (fermata potenzialità dell&#39;esperimento). A tal fine, rimuovere attentamente 180 microlitri della soluzione, a DIV3, e aggiungere 200 microlitri NGF nuovo mezzo e contenente gli elementi complementari di interesse a doppia concentrazione (2). </li></ol></li></ol> 4. Time-lapse imaging Utilizzare un microscopio invertito per le analisi. Vari obiettivi possono essere utilizzati, definire il campo di vista e l&#39;ingrandimento. Un aspetto importante, tuttavia, è la distanza di lavoro dell&#39;obiettivo utilizzato, come l&#39;imaging degli espianti SCG viene eseguita attraverso il vetrino e il collagenegel. Il frame rate di registrazione di 1/10-30 minuti ha mostrato buoni risultati (2). Tuttavia, questo aspetto deve essere adattata alla domanda scientifica. Una telecamera CCD normale può essere utilizzato per l&#39;acquisizione dell&#39;immagine. Per l&#39;imaging time lapse una coltura cellulare camera di incubazione deve essere attaccata alla fase del microscopio. Incubare il tessuto durante l&#39;esposizione a 37 ° C, con il 5% di CO 2 e condizioni umide. Avviare il sistema di incubazione uno ora prima dell&#39;inizio imaging. Ciò consente alle parti microscopio (es. obiettivo) compresa la camera di scorrimento per regolare la temperatura e impedisce derive termiche indotte. Definire le aree specifiche di analisi (entro il espianto e tra espianti diversi) con l&#39;aiuto del software microscopio e con un programma di controllo fase motore (installazione multiposizione) per le analisi simultanee di diverse condizioni applicate agli espianti SCG. Per time-lapse immagini dei tessuti di tipo selvatico e tessuti di animali transgenici può essere utilizzatosegnando la SC (S100B: GFP) (3). Per fluorofori immagini una sorgente di luce fluorescente deve essere attuata nel setup micropscope. Utilizzare i filtri standard. 5. Quantificazione dei SC distanze di migrazione <ol><li> Al punto finale (DIV4 per esempio), fissare il gel di collagene con il 4% PFA nella scatola di controllo per ora 3-4. Consecutivamente lavare i gel di collagene 5 volte per 10 minuti con PBS. Applicare protocolli standard per l&#39;immunoistochimica (2). Se siete nuovi alla preparazione di SCGS, verificare l&#39;identità del ganglio come un ganglio simpatico di immunoistochimica contro la tirosina idrossilasi (TH), un marcatore per le cellule catecolaminergici comune. Durante immunoistochimica (dopo l&#39;anticorpo primario), trasferire i contenenti gel di collagene explant a piastre da 24 pozzetti, che hanno un volume maggiore, che è vantaggioso per il lavaggio del gel. </li><li> Dopo immunoistochimica, posizionare con attenzione il gel di collagene su vetrini. Attentamenterimuovere la soluzione restante e lasciare asciugare il collagene / ridursi a due dimensioni. Questo permette facili misurazioni di distanze (2). Dopo questo, montare i campioni. </li><li> Infine, misurare le distanze di migrazione con l&#39;aiuto di Figi (NIH) software. Nessun plugin speciali sono necessari a tal fine. Per consentire misurazioni corrette in pm, controllare i metadati corretto imaging e le impostazioni con il Fiji, l&#39;immagine e la scala. Utilizzare Fiji anche per la quantificazione delle cellule. </li></ol>

<ol>
	<li>Ebendal, T., Rush, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Use of collagen gels to bioassay nerve growth factor activity. IBRO Handh, (1989).</li><li>Heermann, S., Schm&#195;cker, J., Hinz, U., Rickmann, M., Unterbarnscheidt, T., Schwab, M. H., Krieglstein, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuregulin+1+type+III/ErbB+signaling+is+crucial+for+Schwann+cell+colonization+of+sympathetic+axons.">Neuregulin 1 type III/ErbB signaling is crucial for Schwann cell colonization of sympathetic axons.</a> PloS One. 6 (12), e28692 (2011).</li><li>Zuo, Y., Lubischer, J. L., Kang, H., Tian, L., Mikesh, M., Marks, A., Scofield, V. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+proteins+expressed+in+mouse+transgenic+lines+mark+subsets+of+glia,+neurons,+macrophages,+and+dendritic+cells+for+vital+examination.">Fluorescent proteins expressed in mouse transgenic lines mark subsets of glia, neurons, macrophages, and dendritic cells for vital examination.</a> The Journal of Neuroscience. The Official Journal of the Society for Neuroscience. 24 (49), 10999-11009 (2004).</li><li>Levi-Montalcini, R., Booker, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=EXCESSIVE+GROWTH+OF+THE+SYMPATHETIC+GANGLIA+EVOKED+BY+A+PROTEIN+ISOLATED+FROM+MOUSE+SALIVARY+GLANDS.">EXCESSIVE GROWTH OF THE SYMPATHETIC GANGLIA EVOKED BY A PROTEIN ISOLATED FROM MOUSE SALIVARY GLANDS.</a> Proceedings of the National Academy of Sciences of the United States of America. 46 (3), 373-384 (1960).</li><li>Meintanis, S., Thomaidou, D., Jessen, K. R., Mirsky, R., Matsas, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neuron-glia+signal+beta-neuregulin+promotes+Schwann+cell+motility+via+the+MAPK+pathway.">The neuron-glia signal beta-neuregulin promotes Schwann cell motility via the MAPK pathway.</a> Glia. 34 (1), 39-51 (2001).</li><li>Yamauchi, J., Miyamoto, Y., Chan, J. R., Tanoue, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ErbB2+directly+activates+the+exchange+factor+Dock7+to+promote+Schwann+cell+migration.">ErbB2 directly activates the exchange factor Dock7 to promote Schwann cell migration.</a> The Journal of cell biology. 181 (2), 351-365 (2008).</li><li>Anton, E. S., Weskamp, G., Reichardt, L. F., Matthew, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nerve+growth+factor+and+its+low-affinity+receptor+promote+Schwann+cell+migration.">Nerve growth factor and its low-affinity receptor promote Schwann cell migration.</a> Proceedings of the National Academy of Sciences of the United States of America. 91 (7), 2795-2799 (1994).</li><li>Mahanthappa, N. K., Anton, E. S., Matthew, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glial+growth+factor+2,+a+soluble+neuregulin,+directly+increases+Schwann+cell+motility+and+indirectly+promotes+neurite+outgrowth.">Glial growth factor 2, a soluble neuregulin, directly increases Schwann cell motility and indirectly promotes neurite outgrowth.</a> The Journal of Neuroscience: The Official Journal of the Society for Neuroscience. 16 (15), 4673-4683 (1996).</li><li>Yamauchi, J., Chan, J. R., Shooter, 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=Neurotrophins+regulate+Schwann+cell+migration+by+activating+divergent+signaling+pathways+dependent+on+Rho+GTPases.">Neurotrophins regulate Schwann cell migration by activating divergent signaling pathways dependent on Rho GTPases.</a> Proceedings of the National Academy of Sciences of the United States of America. 101 (23), 8774-8779 (2004).</li><li>Gumy, L. F., Bampton, E. T. W., Tolkovsky, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hyperglycaemia+inhibits+Schwann+cell+proliferation+and+migration+and+restricts+regeneration+of+axons+and+Schwann+cells+from+adult+murine+DRG.">Hyperglycaemia inhibits Schwann cell proliferation and migration and restricts regeneration of axons and Schwann cells from adult murine DRG.</a> Molecular and Cellular Neurosciences. 37 (2), 298-311 (2008).</li><li>Sakaue-Sawano, A., Kurokawa, H., Morimura, T., Hanyu, A., Hama, H., Osawa, H., Kashiwagi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+spatiotemporal+dynamics+of+multicellular+cell-cycle+progression.">Visualizing spatiotemporal dynamics of multicellular cell-cycle progression.</a> Cell. 132 (3), 487-498 (2008).</li><li>Park, D., Don, A. S., Massamiri, T., Karwa, A., Warner, B., MacDonald, J., Hemenway, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+imaging+of+cell+death+using+an+Hsp90+ligand.">Noninvasive imaging of cell death using an Hsp90 ligand.</a> Journal of the American Chemical Society. 133 (9), 2832-2835 (2011).</li><li>Shcherbo, D., Souslova, E. A., Goedhart, J., Chepurnykh, T. V., Gaintzeva, A., Shemiakina, I. I., Gadella, T. W. J., Lukyanov, S., Chudakov, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+and+reliable+FRET/FLIM+pair+of+fluorescent+proteins.">Practical and reliable FRET/FLIM pair of fluorescent proteins.</a> BMC Biotechnology. 9, 24 (2009).</li></ol>

Nessun conflitto di interessi dichiarati.

Lo sviluppo del sistema nervoso periferico è un processo eccitante. Quando l&#39;elaborazione è completata, assoni sono ensheathed da SCS per tutta la lunghezza, che può, in esseri umani, spesso oltre 100 cm. A tal fine il numero corretto dei SCs necessari deve essere stabilito durante lo sviluppo e la SCS devono anche muoversi lungo assoni si estendono verso la periferia per garantire la copertura completa assonale. Questo vale per assoni unmeylinated mielinizzati ma anche per. In entrambi i casi tutti assoni sono i...

<table border="1"><tbody><tr><td> Nome del reagente / materiale </td><td> Azienda </td><td> Numero di catalogo </td><td> Commenti </td></tr><tr><td> MEM 10x </td><td> Gibco </td><td> 21430 </td><td></td></tr><tr><td> Bicarbonato di Sodio (7,5%) </td><td> Gibco </td><td> 25080 </td><td></td></tr><tr><td> Glutammina </td><td> Gibco </td><td> 25030 </td><td></td></tr><tr><td> NaOH </td><td> Merck </td><td> 109137 </td><td></td></tr><tr><td> NGF </td><td> Roche </td><td> 1058231 </td><td> R &amp; S # 556-NG-100 </td></tr><tr><td> Medio Neurobasal </td><td> Gibco </td><td> 21103 </td><td></td></tr><tr><td> B27 Supplemento </td><td> Gibco </td><td> 17504 </td><td></td></tr><tr><td> antibiotici </td><td> Gibco </td><td> 15640 </td><td></td></tr><tr><td> d-PBS </td><td> Gibco </td><td> 14040 </td><td></td></tr><tr><td> aghi insetti </td><td> FST </td><td> 26002-20 </td><td></td></tr><tr><td> siringa con ago </td><td> Braun </td><td></td><td> BD # 300013 </td></tr><tr><td> 8 Fare scorrere camera ben </td><td> Lab tek </td><td> 177402 </td><td></td></tr></tbody></table>

analyzing murine schwann cell development along growing axons

Lo sviluppo dei nervi periferici è un processo intrigante. I neuroni inviano assoni per innervare obiettivi specifici, che negli esseri umani sono spesso più di 100 cm di distanza dal soma del neurone. Sopravvivenza neuronale durante lo sviluppo dipende destinazione fattori di crescita derivati ​​ma anche sul supporto di cellule di Schwann (SC). A questo fine assoni ensheath SC della regione del soma neuronale (o il passaggio dalla centrale per il sistema nervoso periferico) alla sinapsi o giunzione neuromuscolare. Le cellule di Schwann sono derivati ​​della cresta neurale e la migrazione come precursori lungo gli assoni emergenti fino a quando l&#39;assone è coperto con SCS. Ciò dimostra l&#39;importanza di SC migrazione per lo sviluppo del sistema nervoso periferico e sottolinea la necessità di studiare questo processo. Al fine di analizzare lo sviluppo SC, una messa a punto è necessario che accanto alle SC comprende anche la loro substrato fisiologico per la migrazione, l&#39;assone. Grazie allo sviluppo intrauterino <em&gt; in vivo time-lapse imaging, tuttavia, non è fattibile in vertebrati placentari come topo (mus musculus). Per ovviare a questo, abbiamo adattato il ganglio cervicale superiore (SCG) tecnica di espianto. Dopo il trattamento con il fattore di crescita nervosa (NGF) espianti SCG estendere assoni, seguiti da precursori SC migrano lungo gli assoni dal ganglio alla periferia. La bellezza di questo sistema è che la SC sono derivati ​​da un pool di SC endogena e che migrano lungo i loro assoni proprie fisiologici che crescono contemporaneamente. Questo sistema è particolarmente interessante, in quanto lo sviluppo SC lungo gli assoni possono essere analizzati con time-lapse imaging, aprendo ulteriori possibilità di acquisire conoscenze in migrazione SC.

Crescita assonale è facilitato dal SCG espianti seguito al trattamento con NGF (4) (regime film S1 Figura 1 schema). Questo processo è facilmente visibile da qualsiasi microscopio invertito e può essere seguito da time-lapse imaging (film S2). Se uno scienziato è una novità per la dissezione SCG da embrioni di topo si consiglia vivamente una validazione della tecnica da un semplice anti-tirosina idrossilasi (TH) immunoistochimica. TH è un marker comune per i neuroni catecolamine (...

Watch this Scientific Journal Video about Analyzing Murine Schwann Cell Development Along Growing Axons at JoVE.com

Analyzing Murine Schwann Cell Development Along Growing Axons

Qui descriviamo una delle cellule di Schwann (SC) saggio transizione, in cui SC sono in grado di sviluppare lungo gli assoni si estendono.

Analizzando lo sviluppo delle cellule di Schwann Murine lungo gli assoni in crescita

The  development of peripheral nerves is an intriguing process. Neurons send out  axons to innervate specific targets, which in humans are often more than ...

analyzing-murine-schwann-cell-development-along-growing-axons

Research

JoVE Journal

Neuroscience

11.5K Views.  University of Freiburg. Qui descriviamo una delle cellule di Schwann (SC) saggio transizione, in cui SC sono in grado di sviluppare lungo gli assoni si estendono.

Video: Analyzing Murine Schwann Cell Development Along Growing Axons

Live Imaging of Dorsal Root Axons after Rhizotomy

The primary sensory axons injured by spinal root injuries fail to regenerate into the spinal cord, leading to chronic pain and permanent sensory loss. Regeneration of dorsal root (DR) axons into spinal cord is prevented at the dorsal root entry zone (DREZ), the interface between the CNS and PNS. Our understanding of the molecular and cellular events that prevent regeneration at DREZ is incomplete, in part because complex changes associated with nerve injury have been deduced from postmortem analyses. Dynamic cellular processes, such as axon regeneration, are best studied with techniques that capture real-time events with multiple observations of each living animal. Our ability to monitor neurons serially in vivo has increased dramatically owing to revolutionary innovations in optics and mouse transgenics. Several lines of thy1-GFP transgenic mice, in which subsets of neurons are genetically labeled in distinct fluorescent colors, permit individual neurons to be imaged in vivo1. These mice have been used extensively for in vivo imaging of muscle2-4 and brain5-7, and have provided novel insights into physiological mechanisms that static analyses could not have resolved. Imaging studies of neurons in living spinal cord have only recently begun. Lichtman and his colleagues first demonstrated their feasibility by tracking injured dorsal column (DC) axons with wide-field microscopy8,9. Multi-photon in vivo imaging of deeply positioned DC axons, microglia and blood vessels has also been accomplished10. Over the last few years, we have pioneered in applying in vivo imaging to monitor regeneration of DR axons using wide-field microscopy and H line of thy1-YFP mice. These studies have led us to a novel hypothesis about why DR axons are prevented from regenerating within the spinal cord11.
In H line of thy1-YFP mice, distinct YFP+ axons are superficially positioned, which allows several axons to be monitored simultaneously. We have learned that DR axons arriving at DREZ are better imaged in lumbar than in cervical spinal cord. In the present report we describe several strategies that we have found useful to assure successful long-term and repeated imaging of regenerating DR axons. These include methods that eliminate repeated intubation and respiratory interruption, minimize surgery-associated stress and scar formation, and acquire stable images at high resolution without phototoxicity.

An in vivo imaging protocol to monitor primary sensory axons following dorsal root crush is described. The procedures utilize wide-field fluorescence microscopy and thy1-YFP transgenic mice, and permit repeated imaging of axon regeneration over 4 cm in the PNS and axon interactions with the interface of the CNS.

Imaging in diretta degli assoni spinali dopo rizotomia

The primary sensory axons injured by spinal root injuries fail to regenerate into the spinal cord, leading to chronic pain and permanent sensory loss. ...

Ricerca

Neuroscienze

Single-cell Profiling of Developing and Mature Retinal Neurons

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and gene expression programs for extremely rare cell subsets has been a challenge using standard whole-tissue approaches. Gene expression profiling of individual cells allows for unprecedented access to cell types that comprise only a small percentage of the total tissue1-7. In addition, this technique can be used to examine the gene expression programs that are transiently expressed in small numbers of cells during dynamic developmental transitions8.
This issue of cellular diversity arises repeatedly in the central nervous system (CNS) where neuronal connections can occur between quite diverse cells9. The exact number of distinct cell types is not precisely known, but it has been estimated that there may be as many as 1000 different types in the cortex itself10. The function(s) of complex neural circuits may rely on some of the rare neuronal types and the genes they express. By identifying new markers and helping to molecularly classify different neurons, the single-cell approach is particularly useful in the analysis of cell types in the nervous system. It may also help to elucidate mechanisms of neural development by identifying differentially expressed genes and gene pathways during early stages of neuronal progenitor development.
As a simple, easily accessed tissue with considerable neuronal diversity, the vertebrate retina is an excellent model system for studying the processes of cellular development, neuronal differentiation and neuronal diversification. However, as in other parts of the CNS, this cellular diversity can present a problem for determining the genetic pathways that drive retinal progenitors to adopt a specific cell fate, especially given that rod photoreceptors make up the majority of the total retinal cell population11. Here we report a method for the identification of the transcripts expressed in single retinal cells (Figure 1). The single-cell profiling technique allows for the assessment of the amount of heterogeneity present within different cellular populations of the retina2,4,5,12. In addition, this method has revealed a host of new candidate genes that may play role(s) in the cell fate decision-making processes that occur in subsets of retinal progenitor cells8. With some simple adjustments to the protocol, this technique can be utilized for many different tissues and cell types.

A method for the isolation of single retinal cells and subsequent amplification of their cDNAs is described. Single-cell transcriptomics reveals the degree of cellular heterogeneity present in a tissue and uncovers new marker genes for rare cell populations. The accompanying protocol can be adjusted to suit many different cell types.

Single-cell Profiling dei neuroni retinici maturi e in sviluppo

Highly specialized, but exceedingly small populations of cells play important roles in many tissues. The identification of cell-type specific markers and ...

Isolation and Culture of Neural Crest Cells from Embryonic Murine Neural Tube

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to mesenchymal transition (EMT) and migrates throughout the embryo, giving rise to diverse cell types 1-3. NC also has the unique ability to influence the differentiation and maturation of target organs4-6. When explanted in vitro, NC progenitors undergo self-renewal, migrate and differentiate into a variety of tissue types including neurons, glia, smooth muscle cells, cartilage and bone. 
NC multipotency was first described from explants of the avian neural tube7-9. In vitro isolation of NC cells facilitates the study of NC dynamics including proliferation, migration, and multipotency. Further work in the avian and rat systems demonstrated that explanted NC cells retain their NC potential when transplanted back into the embryo10-13. Because these inherent cellular properties are preserved in explanted NC progenitors, the neural tube explant assay provides an attractive option for studying the NC in vitro. 
To attain a better understanding of the mammalian NC, many methods have been employed to isolate NC populations. NC-derived progenitors can be cultured from post-migratory locations in both the embryo and adult to study the dynamics of post-migratory NC progenitors11,14-20, however isolation of NC progenitors as they emigrate from the neural tube provides optimal preservation of NC cell potential and migratory properties13,21,22. Some protocols employ fluorescence activated cell sorting (FACS) to isolate a NC population enriched for particular progenitors11,13,14,17. However, when starting with early stage embryos, cell numbers adequate for analyses are difficult to obtain with FACS, complicating the isolation of early NC populations from individual embryos. Here, we describe an approach that does not rely on FACS and results in an approximately 96% pure NC population based on a Wnt1-Cre activated lineage reporter23. 
The method presented here is adapted from protocols optimized for the culture of rat NC11,13. The advantages of this protocol compared to previous methods are that 1) the cells are not grown on a feeder layer, 2) FACS is not required to obtain a relatively pure NC population, 3) premigratory NC cells are isolated and 4) results are easily quantified. Furthermore, this protocol can be used for isolation of NC from any mutant mouse model, facilitating the study of NC characteristics with different genetic manipulations. The limitation of this approach is that the NC is removed from the context of the embryo, which is known to influence the survival, migration and differentiation of the NC2,24-28.

Isolation of embryonic neural crest from the neural tube facilitates the use of in vitro methods for studying migration, self-renewal, and multipotency of neural crest.

Isolamento e la coltura delle cellule della cresta neurale da Embryonic Murine tubo neurale

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to ...

A Quantitative Cell Migration Assay for Murine Enteric Neural Progenitors

Neural crest cells (NCC) are a transient and multipotent cell population that originates from the dorsal neural tube and migrates extensively throughout the developing vertebrate embryo. In addition to providing peripheral glia and neurons, NCC generate melanocytes as well as most of the cranio-facial skeleton. NCC migration and differentiation is controlled by a combination of their axial origin along the neural tube and their exposure to regionally distinct extracellular cues. Such contribution of extracellular ligands is especially evident during the formation of the enteric nervous system (ENS), a complex interconnected network of neural ganglia that locally controls (among other things) gut muscle movement and intestinal motility. Most of the ENS is derived from a small initial pool of NCC that undertake a long journey in order to colonize - in a rostral to caudal fashion - the entire length of the prospective gut. Among several signaling pathways known to influence enteric NCC colonization, GDNF/RET signaling is recognized as the most important. Indeed, spatiotemporally controlled secretion of the RET ligand GDNF by the gut mesenchyme is chiefly responsible for the attraction and guidance of RET-expressing enteric NCC to and within the embryonic gut. Here, we describe an ex vivo cell migration assay, making use of a transgenic mouse line possessing fluorescently labeled NCC, which allows precise quantification of enteric NCC migration potential in the presence of various growth factors, including GDNF.

We present an ex vivo cell migration assay that allows precise quantification of enteric neural crest cell migration potential in the presence of various growth factors.

Un saggio di migrazione cellulare quantitativa per murini enterici neurali Progenitori

Neural crest cells (NCC) are a transient and multipotent cell population that originates from the dorsal neural tube and migrates extensively throughout ...

Laser Nanosurgery of Cerebellar Axons In Vivo

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to understand the mechanism that promotes neuronal regeneration, an in-depth analysis of the neuronal types that can remodel after injury is needed. Several studies showed that damaged climbing fibers are capable of regrowing also in adult animals1,2. The investigation of the time-lapse dynamics of degeneration and regeneration of these axons within their complex environment can be performed by time-lapse two-photon fluorescence (TPF) imaging in vivo3,4. This technique is here combined with laser surgery, which proved to be a highly selective tool to disrupt fluorescent structures in the intact mouse cortex5-9.
This protocol describes how to perform TPF time-lapse imaging and laser nanosurgery of single axonal branches in the cerebellum in vivo. Olivocerebellar neurons are labeled by anterograde tracing with a dextran-conjugated dye and then monitored by TPF imaging through a cranial window. The terminal portion of their axons are then dissected by irradiation with a Ti:Sapphire laser at high power. The degeneration and potential regrowth of the damaged neuron are monitored by TPF in vivo imaging during the days following the injury.

Laser Nanosurgery of Cerebellar Axons In Vivo

Two-photon imaging, coupled to laser nanodissection, are useful tools to study degenerative and regenerative processes in the central nervous system with subcellular resolution. This protocol shows how to label, image, and dissect single climbing fibers in the cerebellar cortex in vivo.

Laser nanochirurgia di cerebellari Assoni<em&gt; In Vivo</em

Only a few neuronal populations in the central nervous system (CNS) of adult mammals show local regrowth upon dissection of their axon. In order to ...

Live Imaging of Nicotine Induced Calcium Signaling and Neurotransmitter Release Along Ventral Hippocampal Axons

Sustained enhancement of axonal signaling and increased neurotransmitter release by the activation of pre-synaptic nicotinic acetylcholine receptors (nAChRs) is an important mechanism for neuromodulation by acetylcholine (ACh). The difficulty with access to probing the signaling mechanisms within intact axons and at nerve terminals both in vitro and in vivo has limited progress in the study of the pre-synaptic components of synaptic plasticity. Here we introduce a gene-chimeric preparation of ventral hippocampal (vHipp)&#8211;accumbens (nAcc) circuit in vitro that allows direct live imaging to analyze both the pre- and post-synaptic components of transmission while selectively varying the genetic profile of the pre- vs post-synaptic neurons. We demonstrate that projections from vHipp microslices, as pre-synaptic axonal input, form multiple, reliable glutamatergic synapses with post-synaptic targets, the dispersed neurons from nAcc. The pre-synaptic localization of various subtypes of nAChRs are detected and the pre-synaptic nicotinic signaling mediated synaptic transmission are monitored by concurrent electrophysiological recording and live cell imaging. This preparation also provides an informative approach to study the pre- and post-synaptic mechanisms of glutamatergic synaptic plasticity in vitro.

We developed a gene-chimeric preparation of ventral hippocampal &#8211; accumbens circuit in vitro that allows direct live imaging to analyze presynaptic mechanisms of nicotinic acetylcholine receptors (nAChRs) mediated synaptic transmission. This preparation also provides an informative approach to study the pre- and post-synaptic mechanisms of synaptic plasticity.

Immagini dal vivo di nicotina indotta segnalazione Calcio e neurotrasmettitori uscita Lungo ventrali Hippocampal assoni

Sustained enhancement of axonal signaling and increased neurotransmitter release by the activation of pre-synaptic nicotinic acetylcholine receptors ...

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous system. SC-selective genetic manipulation in living animals is a powerful technique for studying the molecular and cellular mechanisms of SC myelination and demyelination in vivo. While knockout/knockin and transgenic mice are powerful tools for studying SC biology, these methods are costly and time consuming. Viral vector-mediated transgene introduction into the sciatic nerve is a simpler and less laborious method. However, viral methods have limitations, such as toxicity, transgene size constraints, and infectivity restricted to certain developmental stages. Here, we describe a new method that allows selective transfection of myelinating SCs in the rodent sciatic nerve using electroporation. By applying electric pulses to the sciatic nerve at the site of plasmid DNA injection, genes of interest can be easily silenced or overexpressed in SCs in both neonatal and more mature animals. Furthermore, this in vivo electroporation method allows for highly efficient simultaneous expression of multiple transgenes. Our novel technique should enable researchers to efficiently manipulate SC gene expression, and facilitate studies on SC development and function.

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

Here, we present an in vivo technique for gene transfer to Schwann cells (SCs) in the rodent sciatic nerve. This simple technique is useful for investigating signaling mechanisms involved in the development and maintenance of myelinating SCs.

In Vivo Gene Transfer di cellule di Schwann nel nervo sciatico roditori da elettroporazione

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Utilizzando canali lineari Agarose per studiare<em&gt; Drosophila</em&gt; Comportamento larvale Crawling

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

Analyzing Dendritic Morphology in Columns and Layers

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and columns to facilitate brain wiring during development and information processing in developed animals. Postsynaptic neurons elaborate dendrites in type-specific patterns in specific layers to synapse with appropriate presynaptic terminals. The fly medulla neuropil is composed of 10 layers and about 750 columns; each column is innervated by dendrites of over 38 types of medulla neurons, which match with the axonal terminals of some 7 types of afferents in a type-specific fashion. This report details the procedures to image and analyze dendrites of medulla neurons. The workflow includes three sections: (i) the dual-view imaging section combines two confocal image stacks collected at orthogonal orientations into a high-resolution 3D image of dendrites; (ii) the dendrite tracing and registration section traces dendritic arbors in 3D and registers dendritic traces to the reference column array; (iii) the dendritic analysis section analyzes dendritic patterns with respect to columns and layers, including layer-specific termination and planar projection direction of dendritic arbors, and derives estimates of dendritic branching and termination frequencies. The protocols utilize custom plugins built on the open-source MIPAV (Medical Imaging Processing, Analysis, and Visualization) platform and custom toolboxes in the matrix laboratory language. Together, these protocols provide a complete workflow to analyze the dendritic routing of Drosophila medulla neurons in layers and columns, to identify cell types, and to determine defects in mutants.

Here, we show how to analyze dendritic routing of Drosophila medulla neurons in columns and layers. The workflow includes a dual-view imaging technique to improve the image quality and computational tools for tracing, registering dendritic arbors to the reference column array and for analyzing the dendritic structures in 3D space.

Analizzando dendritiche Morfologia in colonne e strati

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and ...

Spectral Reflectometric Microscopy on Myelinated Axons In Situ

In a mammalian nervous system, myelin provides an electrical insulation by enwrapping the axon fibers in a multilayered spiral. Inspired by its highly-organized subcellular architecture, we recently developed a new imaging modality, named spectral reflectometry (SpeRe), which enables unprecedented label-free nanoscale imaging of the live myelinated axons in situ. The underlying principle is to obtain nanostructural information by analyzing the reflectance spectrum of the multilayered subcellular structure. In this article, we describe a detailed step-by-step protocol for performing a basic SpeRe imaging of the nervous tissues using a commercial confocal microscopic system, equipped with a white-light laser and a tunable filter. We cover the procedures of sample preparation, acquisition of spectral data, and image processing for obtaining nanostructural information.

Spectral Reflectometric Microscopy on Myelinated Axons In Situ

Here, we present a step-by-step protocol for imaging myelinated axons in a fixed brain slice using a label-free nanoscale imaging technique based on spectral reflectometry.