Die Autoren bedanken sich bei Karen Lawrence für ihre Hilfe danken, mit dem Abschnitt über Bau der Elektroporation Kammer.

<ol>
	<li>Carroll, S. B., Grenier, J. K., Weatherbee, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> From DNA to diversity : molecular genetics and the evolution of animal design. , (2005).</li><li>Davidson, E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Genomic regulatory systems : development and evolution. , (2001).</li><li>Ptashne, M., Gann, 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> Genes &#38; signals. , (2002).</li><li>Blow, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIP-Seq+identification+of+weakly+conserved+heart+enhancers.">ChIP-Seq identification of weakly conserved heart enhancers.</a> Nat Genet. 42, 806-810 (2010).</li><li>Visel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ChIP-seq+accurately+predicts+tissue-specific+activity+of+enhancers.">ChIP-seq accurately predicts tissue-specific activity of enhancers.</a> Nature. 457, 854-858 (2009).</li><li>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=Electroporation+and+RNA+interference+in+the+rodent+retina+in+vivo+and+in+vitro.">Electroporation and RNA interference in the rodent retina in vivo and in vitro.</a> Proc Natl Acad Sci U S A. 101, 16-22 (2004).</li><li>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=Controlled+expression+of+transgenes+introduced+by+in+vivo+electroporation.">Controlled expression of transgenes introduced by in vivo electroporation.</a> Proc Natl Acad Sci U S A. 104, 1027-1032 (2007).</li><li>LoTurco, J., Manent, J. B., Sidiqi, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+and+improved+tools+for+in+utero+electroporation+studies+of+developing+cerebral+cortex.">New and improved tools for in utero electroporation studies of developing cerebral cortex.</a> Cereb Cortex. 19, 120-125 (2009).</li><li>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=Analysis+of+gene+function+in+the+retina.">Analysis of gene function in the retina.</a> Methods Mol Biol. 423, 259-278 (2008).</li><li>Lee, J., Myers, C. A., Williams, N., Abdelaziz, M., Corbo, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+fine-tuning+of+photoreceptor+cis-regulatory+elements+through+affinity+modulation+of+transcription+factor+binding+sites.">Quantitative fine-tuning of photoreceptor cis-regulatory elements through affinity modulation of transcription factor binding sites.</a> Gene Ther. 17, 1390-1399 (2010).</li><li>Carter-Dawson, L. D., LaVail, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rods+and+cones+in+the+mouse+retina.+II.+Autoradiographic+analysis+of+cell+generation+using+tritiated+thymidine.">Rods and cones in the mouse retina. II. Autoradiographic analysis of cell generation using tritiated thymidine.</a> J Comp Neurol. 188, 263-272 (1979).</li><li>Young, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+differentiation+in+the+retina+of+the+mouse.">Cell differentiation in the retina of the mouse.</a> Anat Rec. 212, 199-205 (1985).</li><li>Corbo, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRX+ChIP-seq+reveals+the+cis-regulatory+architecture+of+mouse+photoreceptors.">CRX ChIP-seq reveals the cis-regulatory architecture of mouse photoreceptors.</a> Genome Res. 20, 1512-1525 (2010).</li><li>Kim, D. 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=A+core+paired-type+and+POU+homeodomain-containing+transcription+factor+program+drives+retinal+bipolar+cell+gene+expression.">A core paired-type and POU homeodomain-containing transcription factor program drives retinal bipolar cell gene expression.</a> J Neurosci. 28, 7748-7764 (2008).</li><li>Karra, D., Dahm, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfection+techniques+for+neuronal+cells.">Transfection techniques for neuronal cells.</a> J Neurosci. 30, 6171-6177 (2010).</li><li>Onishi, A., Peng, G. H., Chen, S., Blackshaw, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pias3-dependent+SUMOylation+controls+mammalian+cone+photoreceptor+differentiation.">Pias3-dependent SUMOylation controls mammalian cone photoreceptor differentiation.</a> Nat Neurosci. 13, 1059-1065 (2010).</li></ol>

Explantation Elektroporation ist eine einfache Möglichkeit zur Quantifizierung der cis-regulatorische Aktivität in den Entwicklungsländern Maus Netzhaut. Im Vergleich zu cis-regulatorische Analyse per Maus Transgenese, ist die Elektroporation viel billiger und erfordert nur neugeborenen Maus Welpen, DNA, Sezierbesteck und Elektroporation / Gewebekultur Ausrüstung. Es ist auch weit weniger zeitaufwendig: Ein Experiment erfordert nur ein paar Stunden Vorbereitungszeit, eine Kultur Zeitraum von etwa acht Tage, und ein paar Stunden am Ende des Experiments für die Bildgebung und Datenanalyse. Explantation Elektroporation ist auch überlegen Zellkultur-basierten cis-regulatorische Analyse, da tatsächliche Netzhautgewebe genutzt wird. Die Netzhaut entwickelt ganz normal in Explantation Kultur-und bildet drei verschiedene Zellschichten (äußere Körnerschicht, innere Körnerschicht und Ganglienzellschicht), obwohl Photorezeptoren äußeren Segmente aufwendigen scheitern. Ein weiterer Vorteil ist, dass Explantation Elektroporation ist in hohem Maße reproduzierbar. Das gleiche Konstrukte in verschiedenen Netzhaut elektroporiert, auch an verschiedenen Tagen, führt in der Regel den gleichen relativen Expression. Darüber hinaus, da die Elektroporation Plasmide gedacht werden, um episomal in den Zellkern gehalten werden und sind nicht in Chromosomen integriert, scheinen sie nicht zu unterliegen den gleichen Integrationsstelle Effekte, die cis-regulatorische Analyse in transgenen Mäusen durchgeführt verteufeln. Explantation Elektroporation hat mehrere Einschränkungen. Erstens können nur Zellen, die sich noch in den Zellzyklus effizient transduziert werden durch Elektroporation 15. Bei P0, Stäbe und andere später geboren retinalen Zelltypen (bipolar, Amakrinzellen, M ller Glia) die wichtigsten Zellpopulationen durch diese Methode gezielt. Elektroporation von Zapfen-Photorezeptoren durch P0 Elektroporation wurde vor 16 berichtet, aber die Effizienz scheint gering zu sein. Eine zweite Einschränkung ist, dass Explantation Kultur über zwei Wochen zu einer fortschreitenden Fehlbildung der Netzhaut und wird daher nicht empfohlen. Wenn Promoter Quantifizierung am späten Zeitpunkten erforderlich ist, jedoch eine in vivo Elektroporation 9 durchgeführt, kann durch Netzhaut-Dissektion gefolgt werden an der gewünschten Zeitpunkt, Flachbild-Montage des seziert Netzhaut und Quantifizierung, wie in Abschnitt 9 beschrieben. Eine dritte Einschränkung ist, dass dieser Test nur mäßig hohem Durchsatz ist. Im Gegensatz zu Zellkultur-basierte Assays, dass Hunderte von Konstrukten in einem einzigen Experiment testen können, benötigt die Technik in diesem Protokoll beschriebenen mindestens eine ganze Maus Netzhaut pro Konstrukt. So kann nur ein paar Dutzend Konstrukte vernünftigerweise an einem Tag elektroporiert werden. Eine weitere Einschränkung in Bezug auf die Quantifizierung der Promotoraktivität mit dem vorliegenden Ansatz ist, dass es ein Potential für &quot;Durchschlagen&quot; der DsRed-Fluoreszenz in den GFP-Kanal, vor allem wenn Assay sehr starke Promotoren. Der Grund dafür ist, dass das Emissionsspektrum teilweise mit der von GFP DsRed. Zur Umgehung dieses Problems sollten optimiert Emissionsfilter verwendet werden, minimieren die spektrale Überlappung zwischen DsRed und GFP werden. Wenn eine solche optimierte Filter-Sets nicht verfügbar sind, wäre eine weitere mögliche Lösung sein, um einen blau-verschoben fluoreszierenden Proteins (zB BFP oder CFP) statt der GFP zu verwenden.

<table border="1"><tbody><tr><th> Name des Reagenzes </th><th> Firma </th><th> Katalog-Nummer </th><th> Kommentare (optional) </th></tr><tr><td> Elektroporation Gericht, MicroSlide 453 </td><td> BTX Harvard Apparatus </td><td> 45-0105 </td><td> Siehe Protokoll Abschnitt 1 für Änderungen </td></tr><tr><td> 100% Silikon Aquarium Zement </td><td> Perfecto Fertigung </td><td></td><td></td></tr><tr><td> Plastic Mikroröhrchen Rack </td><td> Fisher Scientific </td><td> 05-541 </td><td> Nur das Gestell Griff verwendet werden </td></tr><tr><td> Dremel </td><td></td><td></td><td> Zum Schneiden der Griff aus dem Kunststoffrohr-Rack </td></tr><tr><td> DMEM </td><td> Gibco / Invitrogen </td><td> 11965 </td><td></td></tr><tr><td> F12 </td><td> Gibco / Invitrogen </td><td> 11765 </td><td></td></tr><tr><td> L-Glu/pen/strep </td><td> Gibco / Invitrogen </td><td> 10378-016 </td><td> 100X-Konzentration </td></tr><tr><td> Insulin </td><td> Sigma-Aldrich </td><td> I-6634 </td><td> Für 1000X Aktien, zu 5mg/ml in 5mM HCl und Filter-sterilisiert resuspendieren </td></tr><tr><td> FBS </td><td> Gibco / Invitrogen </td><td> 26140-079 </td><td></td></tr><tr><td> ECM 830 Square-wave Elektroporator </td><td> BTX Harvard Apparatus </td><td></td><td></td></tr><tr><td> Nuclepore Filter </td><td> Whatman </td><td> 110606 </td><td> 25mm, 0,2 um </td></tr><tr><td> Gewebekultur-Inkubator </td><td></td><td></td><td> 37 ° C, 5% CO 2 </td></tr><tr><td> Deckgläser # 1.5 </td><td> Fisher Scientific </td><td> 12-544E </td><td> 0,16 mm dick </td></tr><tr><td> Fluoreszierende Verbindung Mikroskop mit Kamera ausgestattet </td><td></td><td></td><td> Kamera sollte einfarbig (zB ORCA-ER-Kamera von Hamamatsu) werden </td></tr><tr><td> EGFP / DsRed-Filter-Set für zusammengesetzte Mikroskop </td><td> Chroma Technology Corp </td><td> 86007 </td><td> Dieser Filter gesetzt minimiert Übersprechen zwischen den roten und grünen chanenels </td></tr><tr><td> ImageJ Software </td><td> NIH </td><td></td><td> <a href="http://rsbweb.nih.gov/ij/">http://rsbweb.nih.gov/ij/</a> </td></tr></tbody></table>

quantifying the activity of cis-regulatory elements in the mouse retina by explant electroporation

Transkriptionsfaktoren innerhalb der zellulären Gen-Netzwerke Kontrolle der raum-zeitlichen Muster und Ebenen des Ausdrucks ihrer Zielgene durch Bindung an cis-regulatorischen Elemente (Cres), kurz (~ 300-600 bp) erstreckt sich von genomischer DNA, die sich stromaufwärts liegen kann, stromabwärts oder innerhalb die Introns der Gene, die sie kontrollieren. Cres (dh, Enhancer / Promotoren) bestehen typischerweise aus mehreren gruppierten Bindungsstellen für beide Transkriptionsaktivatoren und Repressoren 1-3. Sie dienen als logische Integratoren von Transkriptions-Eingang gibt eine einheitliche Ausgabe in Form von raumzeitlich präzise und quantitativ exakt Promotoraktivität. Die meisten Studien von Säugetier-cis-Regelung bis dato auf Maus Transgenese als Mittel zur Untersuchung der Enhancer-Funktion von Cres 4-5 verlassen. Diese Technik ist zeitaufwendig, kostenintensiv und wegen der Insertionsstelle Effekte weitgehend nicht quantitativ. Auf der anderen Seite, haben quantitative Tests für Säugetier-CRE-Funktion in Gewebekultur-Systemen (zB Dual-Luciferase-Assays) entwickelt worden, aber die in-vivo-Relevanz dieser Ergebnisse ist oft ungewiss. Die Elektroporation bietet eine hervorragende Alternative zu herkömmlichen Maus Transgenese in dem Sinn, dass sowohl raum-zeitliche und quantitative Bewertung der cis-regulatorische Aktivität in lebenden Säugetiergewebe. Diese Technik ist besonders nützlich bei der Analyse von cis-Regelung in das zentrale Nervensystem, vor allem in der Hirnrinde und der Netzhaut 6-8. Während Maus Netzhaut Elektroporation, sowohl in vivo und ex vivo, entwickelt worden ist und ausgiebig von Matsuda und Cepko 6-7,9 beschrieben, haben wir kürzlich einen einfachen Ansatz, um die Aktivität der Photorezeptor-spezifischen CREs in elektroporiert Maus Netzhaut 10 quantifizieren entwickelt. Da die Menge an DNA, die in der Netzhaut durch Elektroporation eingebracht wird, kann von Experiment zu Experiment variieren, ist es notwendig, eine Zusammenarbeit elektroporiert &quot;loading control &#39;in allen Experimenten sind. In dieser Hinsicht ist die Technik sehr ähnlich wie die Dual-Luciferase-Assay verwendet, um die Promotoraktivität in kultivierten Zellen zu quantifizieren. Wenn Testen Photorezeptor cis-regulatorische Aktivität, ist die Elektroporation in der Regel in neugeborenen Mäusen (postnatalen Tag 0, P0), die zum Zeitpunkt der Spitze Stab Produktion 11-12 wird durchgeführt. Sobald retinalen Zelltypen werden post-mitotischen, ist die Elektroporation viel weniger effizient. Angesichts der hohen Rate der Stange Geburt in neugeborene Mäuse und die Tatsache, dass Stäbe mehr als 70% der Zellen in der adulten Maus Netzhaut bilden, sind die Mehrzahl der Zellen, die bei P0 elektroporiert sind Stäbe. Aus diesem Grund sind Stäbchen-Photorezeptoren der einfachste Netzhaut Zelltyp über Elektroporation zu studieren. Die Technik, die wir hier beschreiben, ist in erster Linie sinnvoll für die Quantifizierung der Aktivität von Photorezeptoren Cres.

Watch this Scientific Journal Video about Quantifying the Activity of cis-Regulatory Elements in the Mouse Retina by Explant Electroporation at JoVE.com

Quantifying the Activity of cis-Regulatory Elements in the Mouse Retina by Explant Electroporation

Dieses Protokoll beschreibt eine einfache und kostengünstige Möglichkeit, um die Aktivität von cis-regulatorischen Elemente (dh Enhancer / Promotoren) in lebenden Maus Netzhaut via Explantation Elektroporation zu quantifizieren. DNA-Präparation, Netzhaut-Dissektion, die Elektroporation, Netzhaut-Explantat-Kultur, und nach der Fixierung Analyse und Quantifizierung beschrieben.

Die Quantifizierung der Aktivität von Cis-Regulatorische Elemente in der Maus Retina durch Explantation Elektroporation

Transcription factors within cellular gene networks control the spatiotemporal pattern and levels of expression of their target genes by binding to ...

quantifying-activity-cis-regulatory-elements-mouse-retina-explant

Research

JoVE Journal

Neuroscience

Quantifying the Activity of cis-Regulatory Elements in the Mouse Retina by Explant Electroporation

14.4K Aufrufe.  Washington University School of Medicine. Dieses Protokoll beschreibt eine einfache und kostengünstige Möglichkeit, um die Aktivität von cis-regulatorischen Elemente (dh Enhancer / Promotoren) in lebenden Maus Netzhaut via Explantation Elektroporation zu quantifizieren. DNA-Präparation, Netzhaut-Dissektion, die Elektroporation, Netzhaut-Explantat-Kultur, und nach der Fixierung Analyse und Quantifizierung beschrieben.

Serie: Quantifying the Activity of cis-Regulatory Elements in the Mouse Retina by Explant Electroporation

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

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

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

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

Die Transfektion von Maus retinalen Ganglienzellen durch In vivo Elektroporation

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

Forschung

Neurowissenschaften

In vivo Electroporation of Developing Mouse Retina

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

In vivo Electroporation of Developing Mouse Retina

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

In-vivo-Elektroporation von Entwicklung Maus Retina

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

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

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

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

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

Gentransfer an sich entwickelnden Maus Innenohr<em&gt; In Vivo</em&gt; Die Elektroporation

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

In vitro Electroporation of the Lower Rhombic Lip of Midgestation Mouse Embryos

The rhombic lip is an embryonic neuroepithelium located in the hindbrain at the junction between the neural tube and the roofplate of the fourth ventricle (reviewed in 1). The rhombic lip can be subdivided into the upper rhombic lip (URL) which encompasses rhombomere 1 (r1) and generates neurons of the cerebellum and the lower rhombic lip (LRL) which gives rise to diverse neuronal brainstem lineages 2-4. LRL derivatives include the auditory neurons of the cochlear nuclei and those of the precerebellar nuclei that are involved in regulating balance and motor control 5-8. Neurogenesis from the LRL occurs over a large temporal window that encompasses embryonic days (E) 9.5-16.55, 9. Different neuronal lineages emerge from the LRL as postmitotic cells (or are born) during distinct developmental days during this neurogenic window. 
Electroporation of gene expression constructs can be used to manipulate gene expression in LRL progenitors and can potentially change the fate of the neurons produced from this region 10-12. Altering gene expression of LRL progenitors in the mouse via in utero electroporation has been highly successful for manipulating lineages born on embryonic day E12.5 or later 10, 12-14. In utero electroporations prior to E12.5 have been unsuccessful primarily due to the lethality associated with puncturing the fourth ventricle roofplate, a necessary step in delivering exogenous DNA that is electroporated into the LRL. However, many LRL derived lineages arise from the LRL earlier than E12.5 9. These earlier born lineages include the neurons that comprise the lateral reticular, external cuneate, and inferior olivary nuclei of the precerebellar system which function to connect inputs from the spinal cord and cortex to the cerebellum 5. In order to manipulate expression in the LRL of embryos younger than E12.5, we developed an in vitro system in which embryos are placed into culture following electroporation.
This study presents an efficient and effective method for manipulating the gene expression of LRL progenitors at E11.5. Embryos electroporated with green fluorescent protein (GFP) driven from the broadly active CAG promoter reproducibly expressed GFP after 24 hours of culture. A critical aspect of this assay is that gene expression is only altered because of the expression of the exogenous gene and not because of secondary effects that result from the electroporation and culturing techniques. It was determined that the endogenous gene expression patterns remain undisturbed in electroporated and cultured embryos. This assay can be utilized to alter the fate of cells emerging from the LRL of embryos younger than E12.5 through the introduction of plasmids for overexpression or knock down (through RNAi) of different pro-neural transcription factors.

In vitro Electroporation of the Lower Rhombic Lip of Midgestation Mouse Embryos

This study describes the development of an in vitro electroporation technique that allows for the manipulation of gene expression in the lower rhombic lip of midgestation embryos.

In-vitro-Elektroporation von der Unteren Rhombischer Lip von der Schwangerschaft ab muriner Embryonen

The rhombic lip is an embryonic neuroepithelium located in the hindbrain at the junction between the neural tube and the roofplate of the fourth ventricle ...

Genetic Manipulation of the Mouse Developing Hypothalamus through In utero Electroporation

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

Genetic Manipulation of the Mouse Developing Hypothalamus through In utero Electroporation

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

Genetische Manipulation der Maus entwickeln Hypothalamus durch<em&gt; In utero</em&gt; Elektroporation

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

Assessment of Vascular Regeneration in the CNS Using the Mouse Retina

The rodent retina is perhaps the most accessible mammalian system in which to investigate neurovascular interplay within the central nervous system (CNS). It is increasingly being recognized that several neurodegenerative diseases such as Alzheimer&#8217;s, multiple sclerosis, and amyotrophic lateral sclerosis present elements of vascular compromise. In addition, the most prominent causes of blindness in pediatric and working age populations (retinopathy of prematurity and diabetic retinopathy, respectively) are characterized by vascular degeneration and failure of physiological vascular regrowth. The aim of this technical paper is to provide a detailed protocol to study CNS vascular regeneration in the retina. The method can be employed to elucidate molecular mechanisms that lead to failure of vascular growth after ischemic injury. In addition, potential therapeutic modalities to accelerate and restore healthy vascular plexuses can be explored. Findings obtained using the described approach may provide therapeutic avenues for ischemic retinopathies such as that of diabetes or prematurity and possibly benefit other vascular disorders of the CNS.

The rodent retina has long been recognized as an accessible window to the brain. In this technical paper we provide a protocol that employs the mouse model of oxygen-induced retinopathy to study the mechanisms that lead to failure of vascular regeneration within the central nervous system after ischemic injury. The described system can also be harnessed to explore strategies to promote regrowth of functional blood vessels within the retina and CNS.

Beurteilung der Gefäß Regeneration im ZNS Verwenden der Maus Retina

The rodent retina is perhaps the most accessible mammalian system in which to investigate neurovascular interplay within the central nervous system (CNS). ...

Telomerase Activity in the Various Regions of Mouse Brain: Non-Radioactive Telomerase Repeat Amplification Protocol (TRAP) Assay

Telomerase, a ribonucleoprotein, is responsible for maintaining the telomere length and therefore promoting genomic integrity, proliferation, and lifespan. In addition, telomerase protects the mitochondria from oxidative stress and confers resistance to apoptosis, suggesting its possible importance for the surviving of non-mitotic, highly active cells such as neurons. We previously demonstrated the ability of novel telomerase activators to increase telomerase activity and expression in the various mouse brain regions and to protect motor neurons cells from oxidative stress. These results strengthen the notion that telomerase is involved in the protection of neurons from various lesions. To underline the role of telomerase in the brain, we here compare the activity of telomerase in male and female mouse brain and its dependence on age. TRAP assay is a standard method for detecting telomerase activity in various tissues or cell lines. Here we demonstrate the analysis of telomerase activity in three regions of the mouse brain by non-denaturing protein extraction using CHAPS lysis buffer followed by modification of the standard TRAP assay.
In this 2-step assay, endogenous telomerase elongates a specific telomerase substrate (TS primer) by adding TTAGGG 6 bp repeats (telomerase reaction). The telomerase reaction products are amplified by PCR reaction creating a DNA ladder of 6 bp increments. The analysis of the DNA ladder is made by 4.5% high resolution agarose gel electrophoresis followed by staining with highly sensitive nucleic acid stain.
Compared to the traditional TRAP assay that utilize 32P labeled radioactive dCTP&#39;s for DNA detection and polyacrylamide gel electrophoresis for resolving the DNA ladder, this protocol offers a non-toxic time saving TRAP assay for evaluating telomerase activity in the mouse brain, demonstrating the ability to detect differences in telomerase activity in the various female and male mouse brain region.

Telomerase Activity in the Various Regions of Mouse Brain: Non-Radioactive Telomerase Repeat Amplification Protocol TRAP Assay

Telomerase is expressed in the neonatal brain and also in distinct regions of the adult brain. We present a non-toxic time saving TRAP assay for the analysis of telomerase activity in various regions of the mouse brain and detection of differences in telomerase activity between male and female mouse brains.

Telomerase-Aktivität in den verschiedenen Regionen der Maus Gehirn: Nicht-radioaktive Telomerase Repeat Amplification Protocol (TRAP)-Assay

Telomerase, a ribonucleoprotein, is responsible for maintaining the telomere length and therefore promoting genomic integrity, proliferation, and ...

Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina

Retinal cone photoreceptors (cones) serve daylight vision and are the basis of color discrimination. They are subject to degeneration, often leading to blindness in many retinal diseases. Calcium (Ca2+), a key second messenger in photoreceptor signaling and metabolism, has been proposed to be indirectly linked with photoreceptor degeneration in various animal models. Systematically studying these aspects of cone physiology and pathophysiology has been hampered by the difficulties of electrically recording from these small cells, in particular in the mouse where the retina is dominated by rod photoreceptors. To circumvent this issue, we established a two-photon Ca2+ imaging protocol using a transgenic mouse line that expresses the genetically encoded Ca2+ biosensor TN-XL exclusively in cones and can be crossbred with mouse models for photoreceptor degeneration. The protocol described here involves preparing vertical sections (&#8220;slices&#8221;) of retinas from mice and optical imaging of light stimulus-evoked changes in cone Ca2+ level. The protocol also allows &#8220;in-slice measurement&#8221; of absolute Ca2+ concentrations; as the recordings can be followed by calibration. This protocol enables studies into functional cone properties and is expected to contribute to the understanding of cone Ca2+ signaling as well as the potential involvement of Ca2+ in photoreceptor death and retinal degeneration.

Imaging Ca2+ Dynamics in Cone Photoreceptor Axon Terminals of the Mouse Retina

We describe a protocol to monitor Ca2+ dynamics in the axon terminals of cone photoreceptors using an ex-vivo&#160;slice preparation of the mouse retina. This protocol allows comprehensive studies of cone Ca2+ signaling in an important mammalian model system, the mouse.

Imaging Ca<sup&gt; 2+</sup&gt; Dynamik in Cone Photorezeptor Axonterminalen des Maus-Retina

Retinal cone photoreceptors (cones) serve daylight vision and are the basis of color discrimination. They are subject to degeneration, often leading to ...

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 - Gentransfer auf Schwann - Zellen in der Nagerischiasnerv durch Elektroporation

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

Investigating Mammalian Axon Regeneration: In Vivo Electroporation of Adult Mouse Dorsal Root Ganglion

Electroporation is an essential non-viral gene transfection approach to introduce DNA plasmids or small RNA molecules into cells. A sensory neuron in the dorsal root ganglion (DRGs) extends a single axon with two branches. One branch goes to the peripheral nerve (peripheral branch), and the other branch enters the spinal cord through the dorsal root (central branch). After the neural injury, the peripheral branch regenerates robustly whereas the central branch does not regenerate. Due to the high regenerative capacity, sensory axon regeneration has been widely used as a model system to study mammalian axon regeneration in both the peripheral nervous system (PNS) and the central nervous system (CNS). Here, we describe a previously established approach protocol to manipulate gene expression in mature sensory neurons in vivo via electroporation. Based on transfection with plasmids or small RNA oligos (siRNAs or microRNAs), the approach allows for both loss- and gain-of-function experiments to study the roles of genes-of-interests or microRNAs in regulation of axon regeneration in vivo. In addition, the manipulation of gene expression in vivo can be controlled both spatially and temporally within a relatively short time course. This model system provides a unique tool to investigate the molecular mechanisms by which mammalian axon regeneration is regulated in vivo.

Investigating Mammalian Axon Regeneration: In Vivo Electroporation of Adult Mouse Dorsal Root Ganglion

Electroporation is an effective approach to deliver genes of interests into cells. By applying this approach in vivo on the neurons of adult mouse dorsal root ganglion (DRG), we describe a model to study axon regeneration in vivo.

Ermittelnden Säugetier-Axon Regeneration: In Vivo Elektroporation von Erwachsenen Maus Dorsal Root Ganglion

Electroporation is an essential non-viral gene transfection approach to introduce DNA plasmids or small RNA molecules into cells. A sensory neuron in the ...