Il nostro lavoro sulla localizzazione di RNA è supportata da una sovvenzione da parte del NIH (R01GM071049) a KLM.

Parte 1: Trascrizione di mRNA fluorescente. <ol><li> Linearizzare DNA plasmidico contenente l&#39;elemento di localizzazione di RNA o altre sequenze pertinenti e risospendere a 1 mg / mL con DEPC trattati con H 2 O. Il modello di DNA deve avere siti promotore a monte per la trascrizione da T7, SP6, o T3 RNA polimerasi. </li><li> Aggiungere i seguenti reagenti in una provetta sterile 1,5 ml: <table><tbody><tr><td> a. Tx tampone 10X (vedi M &amp; M) </td><td> 2 microlitri </td></tr><tr><td> b. 20X tappo / NTP mix (vedi M &amp; M) </td><td> 1 ml </td></tr><tr><td> c. 1 mM Alexa Fluor 546-14-UTP (Invitrogen) </td><td> 1 ml </td></tr><tr><td> d. UTP, [α-32 P] (1 μCi / mL) (Perkin Elmer) </td><td> 1 ml </td></tr><tr><td> e. DEPC-H 2 O </td><td> 11 microlitri </td></tr><tr><td> f. 0,2 M DTT </td><td> 1 ml </td></tr><tr><td> g. RNasin (Promega) </td><td> 1 ml </td></tr><tr><td> h. modello di DNA lineare </td><td> 1 ml </td></tr><tr><td> i. RNA polimerasi (Promega) </td><td> 1 ml </td></tr></tbody></table></li><li> Mescolare delicatamente i reagenti e centrifugare brevemente (10 sec. In una microcentrifuga). </li><li> Incubare per 2-4 ore a 37 ° C, coprendo il tubo con un foglio di alluminio per evitare photobleaching di fluoroforo. </li><li> Aggiungere 1 ml a 1 mg / ml RNasi-free DNasi (Promega) a degradare DNA stampo. </li><li> Incubare 15 minuti a 37 ° C. </li><li> Aggiungere 79 microlitri 20 mM EDTA (pH 8,0) per arrestare la reazione. </li><li> Togliere 1 ml ad un tubo separato, etichettato come &quot;input&quot; e salvare. </li><li> Spin reazione attraverso un G50 colonna 1 ml (vedi Materiali e Metodi), che includerà nucleotidi prive di personalità giuridica, escludendo l&#39;mRNA pieno lunghezza. </li><li> Concentrare l&#39;RNA per precipitazione dell&#39;etanolo: <ol class="lalpha"><li> Aggiungere 250 microlitri di etanolo al 100%, 10 microlitri 7M CH 3 COONH 4, 1 ml vettore RNA (tRNA di lievito, 10 mg / mL) o 1 glicogeno microlitri (20 mg / ml). </li><li> Mescolare bene e congelare fino solido a -80 ° C per&gt; 30 minuti o in ghiaccio secco per 15 minuti. </li><li> Girare alla massima velocità in microcentrifuga per 15 minuti, il surnatante decantare. </li><li> Lavare con 150 ml di etanolo 75%. </li><li> Spin per 3 minuti a velocità massima in microcentrifuga, sopranatante decantare. </li><li> Asciugare il pellet a 37 ° C per 3 minuti, assicurando che tutti i etanolo è evaporato. </li></ol></li><li> Risospendere in 11 microlitri DEPC-H 2 O e togliere 1 ml ad un tubo separato, etichettato come &quot;incorporati&quot;. </li><li> Determinare l&#39;incorporazione per cento e diluire l&#39;RNA a 50 Nm (vedi Materiali e Metodi di calcolo). </li><li> L&#39;RNA devono essere congelati in 5 aliquote microlitri, ad uso singolo per evitare cicli gelo / disgelo e può essere conservato per diverse settimane a -80 ° C. </li></ol> Parte 2: Preparazione per microiniezione. <ol><li> RNA Preparazione: Scongelare una aliquota di RNA (50 nm) e denaturare l&#39;RNA a 70 ° C per 3-5 minuti. Spin per 10 minuti in microcentrifuga temperatura ambiente alla massima velocità per rimuovere qualsiasi particelle, e tenere in ghiaccio. </li><li> Ovocita Preparazione: <ol class="lalpha"><li> Rimuovere chirurgicamente ovaie da femmine Xenopus laevis (Nasco). </li><li> Pezzi speciali di ovaio Xenopus laevis in una provetta da 50 ml contenente 25 ml di soluzione Collagenasi (vedi Materiali e Metodi). </li><li> Agitare delicatamente a 18 ° C per 15 minuti, o fino a quando gli ovociti sono visibilmente separati da ovaio. A causa di variazione tra le partite, tempo di trattamento collagenasi può variare e devono essere monitorati attentamente un&#39;ispezione visuale per assicurare defoliculation. </li><li> Lasciare ovociti a stabilirsi in tubo, rimuovere la soluzione e lavare gli ovociti con tampone MBSH (vedi Materiali e Metodi). </li><li> Ripetere il lavaggio altre due volte per un totale di tre lavaggi. Questo protocollo isolamento degli ovociti è simile a quella dettagliata Cohen et al., 2009. </li><li> Manualmente sorta di stadio III / IV ovociti (Dumont, 1972) nel buffer MBSH al microscopio standard di dissezione. Ovociti stadio III sono completamente opache, ma bianco, mentre gli ovociti stadio IV, sono leggermente più grandi e punteggiato di pigmento. Ovociti che sono leggermente trasparenti sono troppo giovani e ovociti che completamente pigmentate o distribuzione del pigmento mostra polarizzati sono troppo vecchio. </li></ol></li><li> Ago Preparazione: Tirare e smusso aghi di un diametro esterno di circa 0,05 mm. (Utilizziamo Drummond scientifico capillari da 3,5 pollici (per n. 3-000-203-G / X), uno strumento Sutter Co. micropipetta estrattore e un WPI Inc. beveller.) </li></ol> Parte 3: Microiniezione <ol><li> Calibrare ago con DEPC-H 2 O per erogare 2 nl per iniezione. Siamo davanti carico nostro ago usando un gas-driven microinjector (vedi Materiali e Metodi), e calibrare dimensioni di caduta con un micrometro. </li><li> Carico RNA in ago. </li><li> Luogo ordinati ovociti in un piatto di iniezione contenente tampone MBSH. Noi microinject su un piatto con uno strato di gommapiuma nero. Gli ovociti pallido risaltare su un backgrou biancond. </li><li> Con attenzione iniettare ogni ovocita con 2 nl di RNA a 50 nm. </li><li> Espellere l&#39;RNA, lavare ago con DEPC-H 2 O, e carico di RNA prossimo per l&#39;iniezione. </li></ol> Parte 4: Cultura ovociti <ol><li> Ovociti posto in un pozzetto di una sterile 24 pozzetti (Sigma Aldrich). Ci cultura fino a mille ovociti per pozzetto. </li><li> Eliminare la soluzione tampone e sostituire con 400 microlitri O M C ultura ocyte edium (OCM, vedi Materiali e Metodi) per bene. Luogo piastra di coltura all&#39;interno di un contenitore a tenuta stagna in plastica con un tovagliolo di carta umido per mantenere l&#39;ambiente umido durante cultura. </li><li> Incubare ovociti a 18 ° C per intervalli di tempo compresi tra 8 e 48 ore. </li></ol> Parte 5: fissazione, disidratazione e conservazione degli ovociti <ol><li> Risolvere eventuali ovociti morti e il luogo ovociti sopravvissuti in flaconcini di vetro. Noi abitualmente osserviamo sopravvivenza&gt; 90%. </li><li> Ovociti posto in MEMFA fissativo (vedi Materiali e Metodi) e rock per 20 minuti. Proteggere gli ovociti dalla luce coprendo con un foglio di alluminio. </li><li> Lavare ovociti rimuovendo fissativo e la sostituzione con uguale volume di tampone MBSH. Ripetere questa lavare una volta di più per un totale di due lavaggi. </li><li> Lavare gli ovociti in metanolo anidro: <ol class="lalpha"><li> Rimuovere la metà del volume, sostituire con metanolo. </li><li> Ripetere il punto &quot;a&quot; due volte. </li><li> Rimuovere tutta la soluzione, sostituire con metanolo. </li><li> Ripetere il lavaggio metanolo. </li></ol></li><li> Ovociti possono essere conservati a -20 ° C fino al momento di immagine. </li></ol> Parte 6: Imaging localizzazione di RNA di microscopia confocale <ol><li> Prima di immagini, aggiungere Media Clearing Murray s (2:1 benzil benzoato-benzil alcool) ad un FluoroDish fondo di vetro (WPI Inc.) per coprire la superficie di imaging. </li><li> Trasferire accuratamente l&#39;ovociti da metanolo a FluoroDish, riducendo al minimo il volume di metanolo trasferiti. </li><li> Immagine su un microscopio invertito confocale (Abbiamo utilizzato con successo un LSM510 Zeiss e di una Leica TCS SP2). </li></ol><img src="/files/ftp_upload/1704/1704fig1.jpg" alt="Figura 1" /> Figura 1:.. Visualizzazione di localizzazione subcellulare RNA Microiniezione di trascrizioni fluorescente Etichettato microiniezione A. In seguito, l&#39;RNA marcato con Alexa Fluor 546 è inizialmente limitato al nucleo B. Dopo otto ore di cultura, un RNA fluorescente di controllo può essere visto in modo uniforme distribuito nel citoplasma dell&#39;ovocita. C. Tuttavia, l&#39;RNA fluorescente contenente sequenze che reclutano i macchinari di trasporto può essere visto nel processo di localizzazione subcellulare al polo vegetale dell&#39;ovocita (verso il basso). Barra di scala = 50 micron.

<ol>
	<li>Cohen, S., Au, S., Pant, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microinjection+of+Xenopus+laevis+oocytes.">Microinjection of Xenopus laevis oocytes.</a> JoVE. 24, (2009).</li><li>Dumont, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oogenesis+in+Xenopus+laevis+(Daudin).+I.+Stages+of+oocyte+development+in+laboratory+maintained+animals.">Oogenesis in Xenopus laevis (Daudin). I. Stages of oocyte development in laboratory maintained animals.</a> J. Morphol. 136, 153-179 (1972).</li><li>Gagnon, J. A., Mowry, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA+transport+in+ovo:+Simultaneous+visualization+of+two+RNAs.">RNA transport in ovo: Simultaneous visualization of two RNAs.</a> Mol Reprod Dev. 76, 1115-1115 (2009).</li><li>Gautreau, D., Cote, C. A., Mowry, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+copies+of+a+subelement+from+the+Vg1+RNA+localization+sequence+are+sufficient+to+direct+vegetal+localization+in+Xenopus+oocytes.">Two copies of a subelement from the Vg1 RNA localization sequence are sufficient to direct vegetal localization in Xenopus oocytes.</a> Development. 124, 5013-5020 (1997).</li><li>Lewis, R. A., Gagnon, J. A., Mowry, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PTB/hnRNP+I+is+required+for+RNP+remodeling+during+RNA+localization+in+Xenopus+oocytes.">PTB/hnRNP I is required for RNP remodeling during RNA localization in Xenopus oocytes.</a> Mol Cell Biol. 28, 678-6786 (2008).</li><li>Messitt, T. J., Gagnon, J. A., Kreiling, J. A., Pratt, C. A., Yoon, Y. J., Mowry, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiple+kinesin+motors+coordinate+cytoplasmic+RNA+transport+on+a+subpopulation+of+microtubules+in+Xenopus+oocytes.">Multiple kinesin motors coordinate cytoplasmic RNA transport on a subpopulation of microtubules in Xenopus oocytes.</a> Dev Cell. 15, 426-436 (2008).</li><li>Mowry, K. L., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vegetal+messenger+RNA+localization+directed+by+a+340-nt+RNA+sequence+element+in+Xenopus+oocytes.">Vegetal messenger RNA localization directed by a 340-nt RNA sequence element in Xenopus oocytes.</a> Science. 255, 991-994 (1992).</li><li>Yoon, Y. J., Mowry, K. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Xenopus+Staufen+is+a+component+of+a+ribonucleoprotein+complex+containing+Vg1+RNA+and+kinesin.">Xenopus Staufen is a component of a ribonucleoprotein complex containing Vg1 RNA and kinesin.</a> Development. 131, 3035-3045 (2004).</li></ol>

Esperimenti su animali da laboratorio sono stati eseguiti secondo le linee guida e regolamenti stabiliti dalla Brown University.

Qui abbiamo presentato un protocollo per visualizzare la localizzazione mRNA in ovociti di Xenopus. Questo metodo, utilizzando fluorescente trascrizioni di RNA è più alto rapporto segnale-rumore di quanto precedentemente ottenuti con marcati con digossigenina trascrizioni ed è più semplice e più veloce di approcci basati in situ (Mowry e Melton, 1992, Gautreau et al., 1997). Utilizzando questo metodo, possiamo progettare mutazioni sequenza di RNA e rapidamente test per funzione in vivo. Inoltre, u...

A correction to the step 2 of Part 1 for article Visualizing RNA Localization in Xenopus Oocytes.

Erratum: Visualizing RNA Localization in Xenopus Oocytes

Tx tampone 10X <ul><li class="none"> 60 mM MgCl 2 </li><li class="none"> 400 mM Tris-HCl (pH 7,5) </li><li class="none"> 20 mM spermidina-HCl </li></ul> 20x cap / NTP mix <ul><li class="none"> 10 mM CTP </li><li class="none"> 10 mM ATP </li><li class="none"> 9 mm UTP </li><li class="none"> 2 mM GTP </li><li class="none"> 20 mM G (ppp) G Cap analogico (New England Biolabs) </li></ul> G-50 colonna <ul><li class="none"> Idrato 5 g Sephadex G-50 perle (Sigma Aldrich) in 100 ml di acqua deionizzata H 2 O. DEPC-treat per 30 min. e autoclave. Conservare magazzino incompleto a temperatura ambiente. Prima dell&#39;uso, aggiungere il seguente RNasi-free soluzioni: </li><li class="none"> 0,5 ml 0,2 M EDTA </li><li class="none"> 1 ml 1 M Tris pH 8.0 </li><li class="none"> 0,5 ml 20% SDS </li><li class="none"> Conservare completa soluzione G-50 a 4 ° C. </li><li class="none"> Rimuovere e gettare lo stantuffo da una siringa da 3 ml (BD Biosciences) e posizionare il cilindro della siringa in un tubo da 15 ml (Corning). Collegare la siringa con una piccola quantità di lana di vetro (un tappo circa la metà delle dimensioni di un centesimo). </li><li class="none"> Swirl completo G-50 soluzione per risospendere le sfere. </li><li class="none"> Aggiungere 2 ml di soluzione G-50 alla colonna vuota. </li><li class="none"> Spin per 1 minuto a 1.000 x g in centrifuga da banco. </li><li class="none"> Aggiungere 200 ul DEPC trattati deionizzata H 2 O per ogni colonna. Spin. </li><li class="none"> Ripetere il lavaggio altre due volte per un totale di tre lavaggi. </li><li class="none"> Rimuovere il corpo della siringa per un nuovo tubo 15 ml. </li></ul> Collagenasi soluzione <ul><li class="none"> 75 mg di collagenasi da Clostridium histolyticum (Sigma Aldrich) </li><li class="none"> 25 ml 0,1 M KPO 3 + (pH 7,4) </li></ul> MBSH tampone <ul><li class="none"> 88 mm NaCl </li><li class="none"> 1 mM KCl </li><li class="none"> 2,4 mM NaHCO 3 </li><li class="none"> 0,82 mM MgSO 4 x 7H 2 O </li><li class="none"> 0,33 mm Ca (NO 3) 2 x 4H 2 O </li><li class="none"> 0,41 mM CaCl 2 X 6H 2 O </li><li class="none"> HEPES 10 mM (pH 7,6) </li></ul> Ovocita Cultura Media <ul><li class="none"> 50% di media L15 </li><li class="none"> HEPES 15 mM (pH 7,6) </li><li class="none"> 1 mg / ml di insulina </li><li class="none"> 100 mg / ml di gentamicina </li><li class="none"> 50 U / ml nistatina </li><li class="none"> 50 U / ml di penicillina </li><li class="none"> 50 mg / ml di streptomicina </li></ul> MEMFA soluzione <ul><li class="none"> MOPS 0,1 M (pH 7,4) </li><li class="none"> 2 mM EGTA </li><li class="none"> 1 mM MgSO 4 </li><li class="none"> 3,7% di formaldeide </li></ul> Computing RNA resa <ul><li class="none"> Determinare CPM in &quot;input&quot; e &quot;incorporato&quot; campioni utilizzando un normale contatore a scintillazione. </li><li class="none"> incorporazione = (&quot;integrato&quot;) / (10 x &quot;input&quot;) </li><li class="none"> I valori tipici compresi tra incorporazione ~ 0,03 e 0,10. </li><li class="none"> Tenore massimo teorico per polimerasi diverse: T7, T3, SP6 - 2,64 mg </li><li class="none"> Resa di reazione in mg = (resa massima di polimerasi utilizzato) X (incorporazione) </li><li class="none"> Diluire RNA a 50 Nm = (mg RNA) / 320 / (lunghezza di RNA nelle basi) / (5X10 -8) </li><li class="none"> La reazione solitamente produce ~ 50-100 ml di RNA di 50 nm. </li></ul>

visualizing rna localization in xenopus oocytes

Localizzazione dell&#39;RNA è un meccanismo conservato di stabilire la polarità delle cellule. Vg1 mRNA localizza al polo vegetale ovociti di Xenopus laevis e atti a limitare spazialmente l&#39;espressione genica di VG1 proteine. Stretto controllo VG1 distribuzione in questo modo è richiesto per l&#39;indicazione corretta foglietto embrionale di un embrione in via di sviluppo. Elementi di sequenza di RNA nel 3 &#39;UTR del mRNA, il VG1 elemento di localizzazione (VLE) sono necessari e sufficienti per trasporto diretto. Per studiare il riconoscimento e il trasporto del VG1 mRNA in vivo, abbiamo sviluppato una tecnica di imaging che permette un&#39;analisi approfondita dei trans-fattore di meccanismi di trasporto diretto attraverso una semplice lettura visiva. Per visualizzare la localizzazione di RNA, che sintetizzano fluorescente RNA VLE e microinject questa trascrizione in ovociti individuali. Dopo la cultura degli ovociti per consentire il trasporto del RNA iniettato, gli ovociti vengono fissate e disidratate prima di imaging, microscopia confocale. Visualizzazione di modelli di localizzazione mRNA fornisce una lettura per il monitoraggio del percorso completo di RNA di trasporto e per l&#39;individuazione dei ruoli nel dirigere l&#39;RNA di trasporto per cis-acting elementi all&#39;interno della trascrizione e trans-acting fattori che si legano al VLE (Lewis et al., 2008, Messitt et al., 2008). Abbiamo esteso questa tecnica attraverso la co-localizzazione di RNA e proteine ​​addizionali (Gagnon e Mowry, 2009, Messitt et al., 2008), e in combinazione con la rottura del motore e di proteine ​​del citoscheletro (Messitt et al., 2008) di sondare meccanismi alla base di localizzazione mRNA.

Watch this Scientific Journal Video about Visualizing RNA Localization in Xenopus Oocytes at JoVE.com

Visualizing RNA Localization in Xenopus Oocytes

Visualizzazione di<em&gt; In vivo</em&gt; RNA di trasporto si ottiene microiniezione di fluorescente trascrizioni di RNA in<em&gt; Xenopus</em&gt; Ovociti, seguito dalla microscopia confocale.

Visualizzazione RNA localizzazione in Xenopus Gli oociti

RNA localization is a conserved mechanism of establishing cell polarity.  Vg1 mRNA localizes to the vegetal pole of Xenopus laevis oocytes and acts to ...

visualizing-rna-localization-in-xenopus-oocytes

Research

JoVE Journal

Biology

Visualizing RNA Localization in Xenopus Oocytes

11.5K Views.  Brown University. Visualizzazione di In vivo RNA di trasporto si ottiene microiniezione di fluorescente trascrizioni di RNA in Xenopus Ovociti, seguito dalla microscopia confocale.

Video: Visualizing RNA Localization in Xenopus Oocytes

Patch Clamp Recording of Ion Channels Expressed in  Xenopus Oocytes

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological measurement of single or multiple ion channels in cells. This technique can be applied to ion channels in both their native environment and expressed in heterologous cells, such as oocytes harvested from the African clawed frog, Xenopus laevis. Here, we describe the well-established technique of patch clamp recording from Xenopus oocytes. This technique is used to measure the properties of expressed ion channels either in populations (macropatch) or individually (single-channel recording). We focus on techniques to maximize the quality of oocyte preparation and seal generation. With all factors optimized, this technique gives a probability of successful seal generation over 90 percent. The process may be optimized differently by every researcher based on the factors he or she finds most important, and we present the approach that have lead to the greatest success in our hands.

This is intended as an introduction to patch clamp recording from Xenopus laevis oocytes. It covers vitelline membrane removal, formation of a gigaohm seal (gigaseal), and the optional conversion of the patch to the outside-out topology.

Patch di registrazione pinza dei canali ionici Espressa in ovociti di Xenopus

Since its development by Sakmann and Neher 1, 2, the patch clamp has become established as an extremely useful technique for electrophysiological ...

Ricerca

Biologia

Microinjection of Xenopus Laevis Oocytes

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic transport. Because of its large nucleus and high density of nuclear pore complexes (NPCs), nuclear transport can be easily visualized in the Xenopus oocyte. Much insight into the mechanisms of nuclear import and export has been gained through use of this system (reviewed by Pant&eacute;, 2006). In addition, we have used microinjection of Xenopus oocytes to dissect the nuclear import pathways of several viruses that replicate in the host nucleus. 
Here we demonstrate the cytoplasmic microinjection of Xenopus oocytes with a nuclear import substrate. We also show preparation of the injected oocytes for visualization by thin-sectioning EM, including dissection, dehydration, and embedding of the oocytes into an epoxy embedding resin. Finally, we provide representative results for oocytes that have been microinjected with the capsid of the baculovirus Autographa californica nucleopolyhedrovirus (AcMNPV) or the parvovirus Minute Virus of Mice (MVM), and discuss potential applications of the technique.

Here we demonstrate cytoplasmic microinjection of Xenopus laevis oocytes with a nuclear import substrate, as well as preparation of the injected oocytes for visualization by thin-sectioning electron microscopy.

Microiniezione degli ovociti di Xenopus Laevis

Microinjection of Xenopus laevis oocytes followed by thin-sectioning electron microscopy (EM) is an excellent system for studying nucleocytoplasmic ...

Fertilization of Xenopus oocytes using the Host Transfer Method

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to generate maternal-effect mutant animals. Additionally, many of the techniques to overexpress or inhibit gene function in organisms such as Xenopus and zebrafish fail to sufficiently target critical maternal signaling pathways, such as Wnt signaling. In Xenopus, manipulating gene function in cultured oocytes and subsequently fertilizing them can ameliorate these problems to some extent. Oocytes are manually defolliculated from donor ovary tissue, injected or treated in culture as desired, and then stimulated with progesterone to induce maturation. Next, the oocytes are introduced into the body cavity of an ovulating host female frog, whereupon they will be translocated through the host's oviduct and acquire modifications and jelly coats necessary for fertilization. The resulting embryos can then be raised to the desired stage and analyzed for the effects of any experimental perturbations. This host-transfer method has been highly effective in uncovering basic mechanisms of early development and allows a wide range of experimental possibilities not available in any other vertebrate model organism.

Fertilization of Xenopus oocytes using the Host Transfer Method

Procedure for fertilizing Xenopus oocytes by the host transfer method.

Fertilizzazione Ovociti di Xenopus Utilizzando il metodo di trasferimento Host

Studying the contribution of maternally inherited molecules to vertebrate early development is often hampered by the time and expense necessary to ...

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may also be used to study the structure-function relationship for other ion channels and neurotransmitter receptors1. BK channels are widely expressed in different tissues and have been implicated in many physiological functions, including regulation of smooth muscle contraction, frequency tuning of inner hair cells and regulation of neurotransmitter release2-6. BK channels are activated by membrane depolarization and by intracellular Ca2+ and Mg2+ 6-9. Therefore, the protocol is designed to control both the membrane voltage and the intracellular solution. In this protocol, messenger RNA of BK channels is injected into Xenopus laevis oocytes (stage V-VI) followed by 2-5 days of incubation at 18&deg;C10-13. Membrane patches that contain single or multiple BK channels are excised with the inside-out configuration using patch clamp techniques10-13. The intracellular side of the patch is perfused with desired solutions during recording so that the channel activation under different conditions can be examined. To summarize, the mRNA of BK channels is injected into Xenopus laevis oocytes to express channel proteins on the oocyte membrane; patch clamp techniques are used to record currents flowing through the channels under controlled voltage and intracellular solutions.

Patch Clamp and Perfusion Techniques for Studying Ion Channels Expressed in Xenopus oocytes

Ionic current of BK channels is recorded using patch clamp techniques. BK channels are expressed in Xenopus oocytes by injecting messenger RNA. The intracellular solution during patch clamp recordings is controlled by a perfusion system.

Patch clamp e Tecniche di perfusione per la valutazione dei canali ioni Espresso in Xenopus Ovociti

The protocol presented here is designed to study the activation of the large conductance, voltage- and Ca2+-activated K+ (BK) channels. The protocol may ...

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

In vitro transcription is the synthesis of RNA transcripts by RNA polymerase from a linear DNA template containing the corresponding promoter sequence (T7, T3, SP6) and the gene to be transcribed (Figure 1A). A typical transcription reaction consists of the template DNA, RNA polymerase, ribonucleotide triphosphates, RNase inhibitor and buffer containing Mg2+ ions.
Large amounts of high quality RNA are often required for a variety of applications. Use of in vitro transcription has been reported for RNA structure and function studies such as splicing1, RNAi experiments in mammalian cells2, antisense RNA amplification by the "Eberwine method"3, microarray analysis4 and for RNA vaccine studies5. The technique can also be used for producing radiolabeled and dye labeled probes6. Warren, et al. recently reported reprogramming of human cells by transfection with in vitro transcribed capped RNA7. The T7 High Yield RNA Synthesis Kit from New England Biolabs has been designed to synthesize up to 180 &mu;g RNA per 20 &mu;l reaction. RNA of length up to 10kb has been successfully transcribed using this kit. Linearized plasmid DNA, PCR products and synthetic DNA oligonucleotides can be used as templates for transcription as long as they have the T7 promoter sequence upstream of the gene to be transcribed.
Addition of a 5' end cap structure to the RNA is an important process in eukaryotes. It is essential for RNA stability8, efficient translation9, nuclear transport10 and splicing11. The process involves addition of a 7-methylguanosine cap at the 5' triphosphate end of the RNA. RNA capping can be carried out post-transcriptionally using capping enzymes or co-transcriptionally using cap analogs. In the enzymatic method, the mRNA is capped using the Vaccinia virus capping enzyme12,13. The enzyme adds on a 7-methylguanosine cap at the 5' end of the RNA using GTP and S-adenosyl methionine as donors (cap 0 structure). Both methods yield functionally active capped RNA suitable for transfection or other applications14 such as generating viral genomic RNA for reverse-genetic systems15 and crystallographic studies of cap binding proteins such as eIF4E16.
In the method described below, the T7 High Yield RNA Synthesis Kit from NEB is used to synthesize capped and uncapped RNA transcripts of Gaussia luciferase (GLuc) and Cypridina luciferase (CLuc). A portion of the uncapped GLuc RNA is capped using the Vaccinia Capping System (NEB). A linearized plasmid containing the GLuc or CLuc gene and T7 promoter is used as the template DNA. The transcribed RNA is transfected into HeLa cells and cell culture supernatants are assayed for luciferase activity. Capped CLuc RNA is used as the internal control to normalize GLuc expression.

In vitro Transcription and Capping of Gaussia Luciferase mRNA Followed by HeLa Cell Transfection

This method describes high yield in vitro synthesis of both capped and uncapped mRNA from a linearized plasmid containing the Gaussia luciferase (GLuc) gene. The RNA is purified and a fraction of the uncapped RNA is enzymatically capped using the Vaccinia virus capping enzyme. In the final step, the mRNA is transfected into HeLa cells and cell culture supernatants are assayed for luciferase activity.

Trascrizione in vitro e tappatura mRNA Luciferase Gaussia Seguito da cellule HeLa Transfection

In vitro transcription is the synthesis of RNA transcripts by RNA polymerase from a linear DNA template containing the corresponding promoter sequence ...

Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays

Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating gastric H+,K+-ATPase is more difficult to investigate. Many transport assays utilize radioisotopes to achieve a sufficient signal-to-noise ratio, however, the necessary security measures impose severe restrictions regarding human exposure or assay design. Furthermore, ion transport across cell membranes is critically influenced by the membrane potential, which is not straightforwardly controlled in cell culture or in proteoliposome preparations. Here, we make use of the outstanding sensitivity of atomic absorption spectrophotometry (AAS) towards trace amounts of chemical elements to measure Rb+ or Li+ transport by Na+,K+- or gastric H+,K+-ATPase in single cells. Using Xenopus oocytes as expression system, we determine the amount of Rb+ (Li+) transported into the cells by measuring samples of single-oocyte homogenates in an AAS device equipped with a transversely heated graphite atomizer (THGA) furnace, which is loaded from an autosampler. Since the background of unspecific Rb+ uptake into control oocytes or during application of ATPase-specific inhibitors is very small, it is possible to implement complex kinetic assay schemes involving a large number of experimental conditions simultaneously, or to compare the transport capacity and kinetics of site-specifically mutated transporters with high precision. Furthermore, since cation uptake is determined on single cells, the flux experiments can be carried out in combination with two-electrode voltage-clamping (TEVC) to achieve accurate control of the membrane potential and current. This allowed e.g. to quantitatively determine the 3Na+/2K+ transport stoichiometry of the Na+,K+-ATPase and enabled for the first time to investigate the voltage dependence of cation transport by the electroneutrally operating gastric H+,K+-ATPase. In principle, the assay is not limited to K+-transporting membrane proteins, but it may work equally well to address the activity of heavy or transition metal transporters, or uptake of chemical elements by endocytotic processes.

Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays

We describe a method to quantify the activity of K+-countertransporting P-type ATPases by heterologous expression of the enzymes in Xenopus oocytes and measuring Rb+ or Li+ uptake into individual cells by atomic absorption spectrophotometry. The method is a sensitive and safe alternative to radioisotope flux experiments facilitating complex kinetic studies.

Misurazione di trasporto cationico da Na, K e H, K-ATPasi<em&gt; Xenopus</em&gt; Gli oociti per spettrofotometria di assorbimento atomico: una alternativa a saggi radioisotopi

Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating ...

Facial Transplants in Xenopus laevis Embryos

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. To identify where signaling pathways and tissues act during patterning of the developing face, a 'face transplant' technique has been developed in embryos of the frog Xenopus laevis. A region of presumptive facial tissue (the "Extreme Anterior Domain" (EAD)) is removed from a donor embryo at tailbud stage, and transplanted to a host embryo of the same stage, from which the equivalent region has been removed. This can be used to generate a chimeric face where the host or donor tissue has a loss or gain of function in a gene, and/or includes a lineage label. After healing, the outcome of development is monitored, and indicates roles of the signaling pathway within the donor or surrounding host tissues. Xenopus is a valuable model for face development, as the facial region is large and readily accessible for micromanipulation. Many embryos can be assayed, over a short time period since development occurs rapidly. Findings in the frog are relevant to human development, since craniofacial processes appear conserved between Xenopus and mammals.

Facial Transplants in Xenopus laevis Embryos

A technique for transplanting "Extreme Anterior Domain" facial tissue between Xenopus laevis embryos has been developed. Tissue can be moved from one gene expression background into another, allowing the study of local requirements for craniofacial development and for signaling interactions between facial regions.

Trapianti viso a<em&gt; Xenopus laevis</em&gt; Embrioni

Craniofacial birth defects occur in 1 out of every 700 live births, but etiology is rarely known due to limited understanding of craniofacial development. ...

Xenopus Oocytes: Optimized Methods for Microinjection, Removal of Follicular Cell Layers, and Fast Solution Changes in Electrophysiological Experiments

The Xenopus oocyte as a heterologous expression system for proteins, was first described by Gurdon et al.1 and has been widely used since its discovery (References 2 - 3, and references therein). A characteristic that makes the oocyte attractive for foreign channel expression is the poor abundance of endogenous ion channels4. This expression system has proven useful for the characterization of many proteins, among them ligand-gated ion channels.
The expression of GABAA receptors in Xenopus oocytes and their functional characterization is described here, including the isolation of oocytes, microinjections with cRNA, the removal of follicular cell layers, and fast solution changes in electrophysiological experiments. The procedures were optimized in this laboratory5,6 and deviate from the ones routinely used7-9. Traditionally, denuded oocytes are prepared with a prolonged collagenase treatment of ovary lobes at RT, and these denuded oocytes are microinjected with mRNA. Using the optimized methods, diverse membrane proteins have been expressed and studied with this system, such as recombinant GABAA receptors10-12, human recombinant chloride channels13, Trypanosome potassium channels14, and a myo-inositol transporter15, 16.
The methods detailed here may be applied to the expression of any protein of choice in Xenopus oocytes, and the rapid solution change can be used to study other ligand-gated ion channels.

Xenopus Oocytes: Optimized Methods for Microinjection, Removal of Follicular Cell Layers, and Fast Solution Changes in Electrophysiological Experiments

Optimized procedures for the isolation of single follicles, cytoplasmic RNA microinjections, the removal of surrounding cell layers, and protein expression in Xenopus oocytes are described. In addition, a simple method for fast solution changes in electrophysiological experiments with ligand-gated ion channels is presented.

Xenopus ovociti: Metodi ottimizzate per microiniezione, la rimozione di strati di cellule follicolari e cambiamenti soluzione veloce in esperimenti di elettrofisiologia

The Xenopus oocyte as a heterologous expression system for proteins, was first described by Gurdon et al.1 and has been widely used since its discovery ...

TChIP-Seq: Cell-Type-Specific Epigenome Profiling

Epigenetic regulation plays central roles in gene expression. Since histone modification was discovered in the 1960s, its physiological and pathological functions have been extensively studied. Indeed, the advent of next-generation deep sequencing and chromatin immunoprecipitation (ChIP) via specific histone modification antibodies has revolutionized our view of epigenetic regulation across the genome. Conversely, tissues typically consist of diverse cell types, and their complex mixture poses analytic challenges to investigating the epigenome in a particular cell type. To address the cell type-specific chromatin state in a genome-wide manner, we recently developed tandem chromatin immunoprecipitation sequencing (tChIP-Seq), which is based on the selective purification of chromatin by tagged core histone proteins from cell types of interest, followed by ChIP-Seq. The goal of this protocol is the introduction of best practices of tChIP-Seq. This technique provides a versatile tool for tissue-specific epigenome investigation in diverse histone modifications and model organisms.

We describe a step-by-step protocol for tandem chromatin immunoprecipitation sequencing (tChIP-Seq) that enables the analysis of cell-type-specific genome-wide histone modification.

TChIP-Seq: Cellula-tipo-specifico Epigenome profilatura

Epigenetic regulation plays central roles in gene expression. Since histone modification was discovered in the 1960s, its physiological and pathological ...

Visualizing Lymph Node Structure and Cellular Localization using Ex-Vivo Confocal Microscopy

Lymph nodes (LNs) are organs spread within the body, where the innate immune responses can connect with the adaptive immunity. In fact, LNs are strategically interposed in the path of the lymphatic vessels, allowing intimate contact of tissue antigens with all resident immune cells in the LN. Thus, understanding the cellular composition, distribution, location and interaction using ex vivo whole LN imaging will add to the knowledge on how the body coordinates local and systemic immune responses. This protocol shows an ex vivo imaging strategy following an in vivo administration of fluorescent-labeled antibodies that allows a very reproducible and easy-to-perform methodology by using conventional confocal microscopes and stock reagents. Through subcutaneous injection of antibodies, it is possible to label different cell populations in draining LNs without affecting tissue structures that can be potentially damaged by a conventional immunofluorescence microscopy technique.

This protocol describes a technique to image different cell populations in draining lymph nodes without alterations in the organ structure.