Il nostro lavoro è supportato anche da finanziamenti NIH / NIGMS, NSF, USDA / NIFA e BARD a VC.

Fondo Symplastic trasporto di macromolecole attraverso connessioni impianto intercellulari, il plasmodesmi, è di interesse per molti patologi vegetali e biologi. Per esempio, diverse proteine ​​virali sono noti per regolare plasmodesmal limiti di esclusione dimensioni per permettere il movimento virale 1-3. Inoltre, alcune proteine ​​endogene, tra i quali importanti regolatori dello sviluppo, si presume per passare da una cella all&#39;altra, presumibilmente attraverso plasmodesmi, per funzionare non-cell-autonomo 4. Così, una metodologia affidabile per identificare e visualizzare il trasporto macromolecolare tra cellule vegetali è molto richiesto. 1) Far crescere le piantine bersaglio Per la trasformazione ad alta efficienza, piante sane, robuste dovrebbe essere usato. 1. Arabidopsis piante Crescere una pianta di Arabidopsis su Pro-Mix BX in un vaso (10 cm x 10 cm x 10 cm) in un ambiente controllato da camera con un fotoperiodo breve (8 ore di 130-150 μE m -2 s -1 luce a 23 ° C/16 ore al buio a 20 ° C) e del 40-65% di umidità relativa da 6 a 8 settimane 5. Fecondarle tanto in tanto con prodotti disponibili in commercio, come descritto 5. Foglie con la dimensione maggiore di 15 mm x 35 mm (la misura di lunghezza include picciolo) vengono selezionati per gli esperimenti. 2. N. benthamiana e N. tabacum Cresce una pianta su Pro-Mix BX in un vaso (20 cm x 20 cm x 20 cm) in un ambiente controllato da camera con un fotoperiodo lungo (16 ore di 130-150 μE m -2 s -1 luce a 23 ° C / 8 ore al buio a 20 ° C) e del 40-65% di umidità relativa da 7 a 10 settimane. Fecondarle tanto in tanto con prodotti disponibili in commercio come descrivere. Foglie con dimensioni maggiori di 50 mm x 70 mm per N. benthamiana, o 100 mm x 125 mm per N. tabacum (queste misure di lunghezza non comprendono picciolo) vengono selezionati per gli esperimenti. 2) Preparazione della cartuccia Gene Gun con DNA microparticelle rivestite d&#39;oro Il protocollo per questa fase sperimentale è stato descritto in dettaglio in precedenza 6. E &#39;molto importante usare bene purificato il DNA plasmidico ad alte concentrazioni (~ 1 mg / mL) per ottenere la massima efficienza di trasformazione per la facilità di analisi di microscopia confocale durante le fasi successive della sperimentazione. Per questo test, è importante accertarsi che la cartuccia preparato non trasformare due o più celle adiacenti contemporaneamente ad alta frequenza, perché i numeri di cellule associazione con un cluster segnale fluorescente viene utilizzato come indicatore del grado di trasporto symplastic (cioè , una singola cellula che contiene il segnale indica nessun movimento, mentre un cluster segnale multicella indica il movimento). La qualità dei ogni cartuccia può essere verificato analizzando l&#39;espressione della proteina 16-20 dopo bombardamento ore. Il nostro protocollo 6 produce cartucce che producono cluster espressione multicella solo in &lt;3% di tutti gli eventi espressione in questo lasso di tempo, quindi adatto per questo esperimento. 3) Consegna Biolistic di microparticelle rivestite di DNA <ol><li> Togliere le foglie della stessa fase di sviluppo (cioè con le stesse dimensioni e stessa età, vedi punto 1) con una lama di rasoio affilato e immediatamente posto con i lati abaxial rivolto verso l&#39;alto su una superficie piana di polistirolo. Il lato abaxial della foglia rappresenta un substrato migliore per il bombardamento a causa della sua densità tricomi più basso e più sottile cuticola. Foglie di Arabidopsis, a causa delle loro dimensioni relativamente piccole, dovrebbero essere coperti con un pezzo di maglia finestra dello schermo, e la rete poi fissato con pushpins alla superficie di polistirolo. Il mantenimento di foglie piatte aumenta l&#39;efficienza della consegna delle particelle e riduce al minimo i danni al tessuto durante microbombardment. </li><li> Inserire la cartuccia con microparticelle rivestite di DNA (preparata al punto 1) nella pistola. Per Arabidopsis, il tiro viene eseguita a pressioni di 80-110 psi per 1-micron microparticelle, e 140-160 psi per 0,6 micron microparticelle. Per N. benthamiana e tabacco, il tiro viene eseguita a pressioni di 100-120 psi per 1-micron microparticelle, e 160-180 psi per 0,6 micron microparticelle. Per Arabidopsis, di solito si utilizza una cartuccia per anta, in quanto ogni foglia ha uno spazio sufficiente superficie per un solo colpo microparticelle che si estende su una superficie di 10-12 mm di diametro. Con grande N. benthamiana e foglie di tabacco, bombardamenti multipli della stessa foglia sono possibili, tuttavia, deve essere fatto nelle posizioni simmetriche ai lati della venatura di indirizzare le aree foglia allo stesso stadio di sviluppo (vedi Discussione). </li><li> Togliere le foglie dalla superficie di polistirolo e li hoNon una piastra di Petri, il 3 strati di carta bagnata Whatman filtro, sigillare la piastra di Petri con Parafilm, e incubare a temperatura ambiente per 36-48 ore per consentire l&#39;espressione dei transgeni consegnato e il potenziale cellula-cellula movimento dei loro prodotti proteici . </li></ol> 4) Imaging di espressione proteica Il segnale di fluorescenza delle proteine ​​espresse transitoriamente tag è visualizzata mediante microscopia confocale. Si deve prestare attenzione per trovare le impostazioni ottimali per il rilevamento microscopia di ogni proteina testato. Per esempio, le proteine ​​che mostrano limitato accumulo intracellulare con intensità di segnale debole, come ad esempio la localizzazione della proteina plasmodesmal movimento virus del mosaico del tabacco (TMV MP) 1-3,6, deve essere osservata sotto una lente obiettivo 40X, che offre una risoluzione più alta e sensibilità, mentre le proteine ​​che mostrano la distribuzione citoplasmatica con intensità segnale forte, come la connessione YFP, possono essere visualizzati sotto una lente obiettivo 10X con funzione di zoom per una più rapida l&#39;imaging confocale (vedi Figura 1). Trasporto Symplastic è dedotta dalla comparsa di cluster multicella che contengono il segnale fluorescente. Il numero di tali aggregati e il numero di cellule in ogni cluster è indicativo del grado di cellula-cellula di trasporto. Per ottenere dati affidabili, almeno 100 cluster espressione dovrebbe essere registrate per ogni sistema sperimentale. Per esempio, se la cellula-cellula movimento di una proteina è confrontato in due diversi sfondi genetici (per esempio, di tipo selvatico e piante transgeniche), su un totale di 200 ammassi espressione dovrebbe essere registrato. Soprattutto, esperimenti, i cui risultati devono essere confrontati gli uni agli altri, deve essere effettuata contemporaneamente. 5. Rappresentante Risultati La figura seguente illustra gli esperimenti di rappresentanza per il rilevamento di trasporto symplastic delle proteine ​​fluorescenti tag. Pannelli A e B mostrano le immagini tipiche confocale che si ottengono microbombardment seguito di una N. foglia benthamiana con un MP TMV-YFP che esprimono costruire. Nel pannello A, movimento symplastic di TMV MP-YFP si osserva basa sulla comparsa di grappoli multicella del segnale YFP. Non tutti i transitoriamente espressa TMV MP-YFP è in grado di muoversi come evidenziato da singole cellule del segnale in alcune microbombardments (pannello B). Statisticamente, in &lt;40% dei glomeruli segnale contati, TMV MP-YFP è in grado di spostarsi tra le celle mentre nel&gt; 60% dei glomeruli, la proteina si muove tra 2-5 cellule, con le due celle diffuso è il più frequente (ca. casi ~ 50%) (Figura 1C). Le proteine ​​con relativamente piccole dimensioni molecolari in assenza di attività moto innato può diffondersi attraverso il PD per spostare cellula-cellula. Per esempio, YFP libero, o 1xYFP (ca. 27 kDa, pannello D), si diffonde tra le diverse celle nel 30% dei glomeruli contati (pannelli C). Questo non specifici diffusione non si verifica per un dimmer YFP traslazionale, o 2xYFP (54 kDa, e pannello), che è paragonabile per dimensioni a TMV MP-YFP proteina di fusione (57 kDa), e che è completamente cellule autonome (Figura 1C). <img src="/files/ftp_upload/2208/2208fig1.jpg" alt="Figura 1" /> Risultati Figura 1. Tipici ottenuti dal test di trasporto symplastic in N. benthamiana foglia tessuti. (A, B) Visualizzazione del TMV MP-YFP. (C) Quantificazione dei cluster segnale. 1xYFP e 2xYFP, libero YFP e traslazionale YFP dimero, rispettivamente. (D) Visualizzazione 1xYFP. (E) Visualizzazione 2xYFP. In micrografie, i pannelli sinistra mostrano il segnale YFP e pannelli di destra mostrano le immagini fuse di YFP (in verde) e autofluorescenza cloroplasto (in bianco) i segnali. Le immagini sono singole sezioni confocale. Asterischi nei micrografie mostrano le cellule epidermiche che mostra segnali YFP. Bar = 50 micron.

<ol>
	<li>Waigmann, E., Ueki, S., Trutnyeva, K., Citovsky, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ins+and+outs+of+non-destructive+cell-to-cell+and+systemic+movement+of+plant+viruses.+.">The ins and outs of non-destructive cell-to-cell and systemic movement of plant viruses. .</a> Crit Rev Plant Sci. 23, 195-250 (2004).</li><li>Lucas, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+viral+movement+proteins:+agents+for+cell-to-cell+trafficking+of+viral+genomes.">Plant viral movement proteins: agents for cell-to-cell trafficking of viral genomes.</a> Virology. 344, 169-184 (2006).</li><li>Epel, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+viruses+spread+by+diffusion+on+ER-associated+movement-protein-rafts+through+plasmodesmata+gated+by+viral+induced+host+beta-1,3-glucanases.">Plant viruses spread by diffusion on ER-associated movement-protein-rafts through plasmodesmata gated by viral induced host beta-1,3-glucanases.</a> Semin Cell Dev Biol. 20, 1074-1081 (2009).</li><li>Zambryski, P. C., Crawford, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmodesmata:+gatekeepers+for+cell-to-cell+transport+of+developmental+signals+in+plants.">Plasmodesmata: gatekeepers for cell-to-cell transport of developmental signals in plants.</a> Annu Rev Cell Dev Biol. 16, 393-421 (2000).</li><li>Rivero-Lepinckas, L., Crist, D., Scholl, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+plants+and+presercation+of+seeds.">Growth of plants and presercation of seeds.</a> Methods Mol Biol. 323, 3-12 (2006).</li><li>Ueki, S., Lacroix, B., Krichevsky, A., Lazarowitz, S. G., Citovsky, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+transient+genetic+transformation+of+Arabidopsis+leaves+by+biolistic+bombardment.">Functional transient genetic transformation of Arabidopsis leaves by biolistic bombardment.</a> Nat Protoc. 4, 71-77 (2009).</li><li>Oparka, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple,+but+not+branched,+plasmodesmata+allow+the+nonspecific+trafficking+of+proteins+in+developing+tobacco+leaves.">Simple, but not branched, plasmodesmata allow the nonspecific trafficking of proteins in developing tobacco leaves.</a> Cell. 97, 743-754 (1999).</li><li>Imlau, A., Truernit, E., Sauer, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-to-cell+and+long-distance+trafficking+of+the+green+fluorescent+protein+in+the+phloem+and+symplastic+unloading+of+the+protein+into+sink+tissues.">Cell-to-cell and long-distance trafficking of the green fluorescent protein in the phloem and symplastic unloading of the protein into sink tissues.</a> Plant Cell. 11, 309-322 (1999).</li><li>Gisel, A., Barella, S., Hempel, F. D., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+and+spatial+regulation+of+symplastic+trafficking+during+development+in+Arabidopsis+thaliana+apices.">Temporal and spatial regulation of symplastic trafficking during development in Arabidopsis thaliana apices.</a> Development. 126, 1879-1889 (1999).</li><li>Kim, I., Cho, E., Crawford, K. M., Hempel, F. D., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-to-cell+movement+of+GFP+during+embryogenesis+and+early+seedling+development+in+Arabidopsis.">Cell-to-cell movement of GFP during embryogenesis and early seedling development in Arabidopsis.</a> Proc Natl Acad Sci USA. 102, 2227-2231 (2005).</li><li>Crawford, K. M., Zambryski, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-targeted+and+targeted+protein+movement+through+plasmodesmata+in+leaves+in+different+developmental+and+physiological+states.">Non-targeted and targeted protein movement through plasmodesmata in leaves in different developmental and physiological states.</a> Plant Physiol. 125, 1802-1812 (2001).</li><li>Roberts, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phloem+unloading+in+sink+leaves+of+Nicotiana+benthamiana:+comparison+of+a+fluorescent+solute+with+a+fluorescent+virus.">Phloem unloading in sink leaves of Nicotiana benthamiana: comparison of a fluorescent solute with a fluorescent virus.</a> Plant Cell. 9, 1381-1396 (1997).</li><li>Guenoune-Gelbart, D., Elbaum, M., Sagi, G., Levy, A., Epel, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tobacco+mosaic+virus+(TMV)+replicase+and+movement+protein+function+synergistically+in+facilitating+TMV+spread+by+lateral+diffusion+in+the+plasmodesmal+desmotubule+of+Nicotiana+benthamiana.">Tobacco mosaic virus (TMV) replicase and movement protein function synergistically in facilitating TMV spread by lateral diffusion in the plasmodesmal desmotubule of Nicotiana benthamiana.</a> Mol Plant Microbe Interact. 21, 335-345 (2008).</li></ol>

Nessun conflitto di interessi dichiarati.

La chiave per il successo del saggio di trasporto symplastic è quello di ottenere elevata efficienza di trasformazione, che consente la produzione di cluster segnale statisticamente significativi e facilmente misurabili. Ciò può essere ottenuto utilizzando le foglie raccolte da piante sane, robuste, e la preparazione di particelle di oro rivestite da una preparazione del DNA puro e concentrato. Utilizzando le foglie in fase di crescita stessa è fondamentale anche per l&#39;affidabilità ...

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		<th>Type</th>
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		<th>Catalogue Number</th>
		<th>Comment</th>
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<td>Gold microparticles, 1.0 &mu;m in diameter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2262</td>
<td>&nbsp;</td>
<tr>
<td>Gold microparticles, 0.6 &mu;m in diameter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2263</td>
<td>&nbsp;</td>
<tr>
<td>Spermidine</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>S0266-1G</td>
<td>&nbsp;</td>
<tr>
<td>Tefzel tubing</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2441</td>
<td>&nbsp;</td>
<tr>
<td>Helios cartridge preparatory station</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2420</td>
<td>&nbsp;</td>
<tr>
<td>Tubing cutter</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2422</td>
<td>&nbsp;</td>
<tr>
<td>Helios gene gun</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2432</td>
<td>&nbsp;</td>
<tr>
<td>Helium gas regulator</td>
<td>&nbsp;</td>
<td>Bio-Rad</td>
<td>165-2413</td>
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a cell-to-cell macromolecular transport assay in planta utilizing biolistic bombardment

Qui, vi presentiamo un protocollo semplice e rapido per rilevare e valutare l&#39;entità del cellula-cellula trasporto macromolecolari in planta. In questo protocollo, una fluorescente con tag proteina di interesse è transitoriamente espressa in tessuti vegetali dopo la consegna biolistic del suo DNA codifica costruire. La distribuzione intra-ed intercellulare della proteina tag viene quindi analizzato al microscopio confocale. Descriviamo questa tecnologia nel dettaglio, fornendo passo-passo protocolli di saggiare e valutare l&#39;entità del trasporto delle proteine ​​symplastic in tre specie di piante, Arabidopsis thaliana, Nicotiana benthamiana e N. tabacum (tabacco).

Watch this Scientific Journal Video about A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment at JoVE.com

A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

Traffico macromolecolari tra le cellule delle piante può essere valutata transitoriamente esprimere una proteina fluorescente-tagged di interesse e per analizzarne la distribuzione intra-ed intercellulare mediante microscopia confocale.

Una cellula-cellula Macromolecole saggio di trasporto In Planta Utilizzando Bombardamento Biolistic

Here, we present a simple and rapid protocol to detect and assess the extent of cell-to-cell macromolecular transport in planta. In this protocol, a ...

a-cell-to-cell-macromolecular-transport-assay-planta-utilizing

Research

JoVE Journal

Biology

A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

11.8K Views.  State University of New York at Stony Brook. Traffico macromolecolari tra le cellule delle piante può essere valutata transitoriamente esprimere una proteina fluorescente-tagged di interesse e per analizzarne la distribuzione intra-ed intercellulare mediante microscopia confocale.

Video: A Cell-to-cell Macromolecular Transport Assay in Planta Utilizing Biolistic Bombardment

Generation of Transgenic C. elegans by Biolistic Transformation

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Generation of Transgenic C. elegans by Biolistic Transformation

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

Generazione di transgenici C. elegans Di Trasformazione Biolistic

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid ...

Ricerca

Biologia

Harvesting and Cryo-cooling Crystals of Membrane Proteins Grown in Lipidic Mesophases for Structure Determination by Macromolecular Crystallography

An important route to understanding how proteins function at a mechanistic level is to have the structure of the target protein available, ideally at atomic resolution. Presently, there is only one way to capture such information as applied to integral membrane proteins (Figure 1), and the complexes they form, and that method is macromolecular X-ray crystallography (MX). To do MX diffraction quality crystals are needed which, in the case of membrane proteins, do not form readily. A method for crystallizing membrane proteins that involves the use of lipidic mesophases, specifically the cubic and sponge phases1-5, has gained considerable attention of late due to the successes it has had in the G protein-coupled receptor field6-21 (<a href="http://www.mpdb.tcd.ie" target="_blank">www.mpdb.tcd.ie</a>). However, the method, henceforth referred to as the in meso or lipidic cubic phase method, comes with its own technical challenges. These arise, in part, due to the generally viscous and sticky nature of the lipidic mesophase in which the crystals, which are often micro-crystals, grow. Manipulating crystals becomes difficult as a result and particularly so during harvesting22,23. Problems arise too at the step that precedes harvesting which requires that the glass sandwich plates in which the crystals grow (Figure 2)24,25 are opened to expose the mesophase bolus, and the crystals therein, for harvesting, cryo-cooling and eventual X-ray diffraction data collection.
The cubic and sponge mesophase variants (Figure 3) from which crystals must be harvested have profoundly different rheologies4,26. The cubic phase is viscous and sticky akin to a thick toothpaste. By contrast, the sponge phase is more fluid with a distinct tendency to flow. Accordingly, different approaches for opening crystallization wells containing crystals growing in the cubic and the sponge phase are called for as indeed different methods are required for harvesting crystals from the two mesophase types. Protocols for doing just that have been refined and implemented in the Membrane Structural and Functional Biology (MS&amp;FB) Group, and are described in detail in this JoVE article (Figure 4). Examples are given of situations where crystals are successfully harvested and cryo-cooled. We also provide examples of cases where problems arise that lead to the irretrievable loss of crystals and describe how these problems can be avoided. In this article the Viewer is provided with step-by-step instructions for opening glass sandwich crystallization wells, for harvesting and for cryo-cooling crystals of membrane proteins growing in cubic and in sponge phases.

Herein is described procedures implemented in the Caffrey Membrane Structural and Functional Biology Group to harvest and cryo-cool membrane protein crystals grown in lipidic cubic and sponge phases for use in structure determination using macromolecular X-ray crystallography.

Cristalli di raccolta e di Cryo-raffreddamento delle proteine ​​di membrana Grown in mesofasi lipidici per la determinazione della struttura di cristallografia macromolecolare

An important route to understanding how proteins function at a mechanistic level is to have the structure of the target protein available, ideally at ...

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes

Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a crucial role in transepithelial fluid homeostasis1-3. CFTR has been implicated in two major diseases: cystic fibrosis (CF)4 and secretory diarrhea5. In CF, the synthesis or functional activity of the CFTR Cl- channel is reduced. This disorder affects approximately 1 in 2,500 Caucasians in the United States6. Excessive CFTR activity has also been implicated in cases of toxin-induced secretory diarrhea (e.g., by cholera toxin and heat stable E. coli enterotoxin) that stimulates cAMP or cGMP production in the gut7.
Accumulating evidence suggest the existence of physical and functional interactions between CFTR and a growing number of other proteins, including transporters, ion channels, receptors, kinases, phosphatases, signaling molecules, and cytoskeletal elements, and these interactions between CFTR and its binding proteins have been shown to be critically involved in regulating CFTR-mediated transepithelial ion transport in vitro and also in vivo8-19. In this protocol, we focus only on the methods that aid in the study of the interactions between CFTR carboxyl terminal tail, which possesses a protein-binding motif [referred to as PSD95/Dlg1/ZO-1 (PDZ) motif], and a group of scaffold proteins, which contain a specific binding module referred to as PDZ domains. So far, several different PDZ scaffold proteins have been reported to bind to the carboxyl terminal tail of CFTR with various affinities, such as NHERF1, NHERF2, PDZK1, PDZK2, CAL (CFTR-associated ligand), Shank2, and GRASP20-27. The PDZ motif within CFTR that is recognized by PDZ scaffold proteins is the last four amino acids at the C terminus (i.e., 1477-DTRL-1480 in human CFTR)20. Interestingly, CFTR can bind more than one PDZ domain of both NHERFs and PDZK1, albeit with varying affinities22. This multivalency with respect to CFTR binding has been shown to be of functional significance, suggesting that PDZ scaffold proteins may facilitate formation of CFTR macromolecular signaling complexes for specific/selective and efficient signaling in cells16-18.
Multiple biochemical assays have been developed to study CFTR-involving protein interactions, such as co-immunoprecipitation, pull-down assay, pair-wise binding assay, colorimetric pair-wise binding assay, and macromolecular complex assembly assay16-19,28,29. Here we focus on the detailed procedures of assembling a PDZ motif-dependent CFTR-containing macromolecular complex in vitro, which is used extensively by our laboratory to study protein-protein or domain-domain interactions involving CFTR16-19,28,29.

In Vitro Analysis of PDZ-dependent CFTR Macromolecular Signaling Complexes

Cystic fibrosis transmembrane conductance regulator (CFTR), an epithelial chloride channel, has been reported to interact with various proteins and regulate important cellular processes; among them the CFTR PDZ motif-mediated interactions have been well documented. This protocol describes methods we developed to assemble a PDZ-dependent CFTR macromolecular signaling complex in vitro.

L&#39;analisi in vitro dei complessi CFTR PDZ-dipendenti macromolecolari di segnalazione

Cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel located primarily at the apical membranes of epithelial cells, plays a ...

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media (mCeHR). Additionally, the steps for exposing and acclimatizing C. elegans grown on E. coli to axenic liquid media are described. Finally, downstream experiments that utilize axenic C. elegans illustrate the benefits of this procedure. The ability to analyze and determine C. elegans&#160;nutrient requirement was illustrated by growing N2 wild type worms in axenic liquid media with varying heme concentrations. This procedure can be replicated with other nutrients to determine the optimal concentration for worm growth and development or, to determine the toxicological effects of drug treatments. The effects of varied heme concentrations on the growth of wild type worms were determined through qualitative microscopic observation and by quantitating the number of worms that grew in each heme concentration. In addition, the effect of varied nutrient concentrations can be assayed by utilizing worms that express fluorescent sensors that respond to changes in the nutrient of interest. Furthermore, a large number of worms were easily produced for the generation of transgenic C. elegans using microparticle bombardment.

Culturing Caenorhabditis elegans in Axenic Liquid Media and Creation of Transgenic Worms by Microparticle Bombardment

C. elegans is usually grown on solid agar plates or in liquid cultures seeded with E. coli. To prevent bacterial byproducts from confounding toxicological and nutritional studies, we utilized an axenic liquid medium, CeHR, to grow and synchronize a large number of worms for a range of downstream applications.

Culturing<em&gt; Caenorhabditis elegans</em &gt; In axeniche Liquid Media e la creazione di transgeniche Worms da microparticelle Bombardamento

In this protocol, we present the required materials, and the procedure for making modified&#160;C. elegans&#160;Habituation and Reproduction media ...

Open Source High Content Analysis Utilizing Automated Fluorescence Lifetime Imaging Microscopy

We present an open source high content analysis instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions using F&#246;rster resonance energy transfer (FRET) based readouts of fixed or live cells in multiwell plates. This provides a means to screen for cell signaling processes read out using intramolecular FRET biosensors or intermolecular FRET of protein interactions such as oligomerization or heterodimerization, which can be used to identify binding partners. We describe here the functionality of this automated multiwell plate FLIM instrumentation and present exemplar data from our studies of HIV Gag protein oligomerization and a time course of a FRET biosensor in live cells. A detailed description of the practical implementation is then provided with reference to a list of hardware components and a description of the open source data acquisition software written in &#181;Manager. The application of FLIMfit, an open source MATLAB-based client for the OMERO platform, to analyze arrays of multiwell plate FLIM data is also presented. The protocols for imaging fixed and live cells are outlined and a demonstration of an automated multiwell plate FLIM experiment using cells expressing fluorescent protein-based FRET constructs is presented. This is complemented by a walk-through of the data analysis for this specific FLIM FRET data set.

We present an open source high content analysis (HCA) instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions using F&#246;rster resonance energy transfer (FRET) based readouts. Data acquisition for this openFLIM-HCA instrument is controlled by software written in &#181;Manager and data analysis is undertaken in FLIMfit.

Open Source alto contenuto di analisi Utilizzando Automated Fluorescence Lifetime Imaging Microscopy

We present an open source high content analysis instrument utilizing automated fluorescence lifetime imaging (FLIM) for assaying protein interactions ...

Optimization of Crystal Growth for Neutron Macromolecular Crystallography

The use of neutron macromolecular crystallography (NMX) is expanding rapidly with most structures determined in the last decade thanks to new NMX beamlines having been built and increased availability of structure refinement software. However, the neutron sources currently available for NMX are significantly weaker than equivalent sources for X-ray crystallography. Despite advances in this field, significantly larger crystals will always be required for neutron diffraction studies, particularly with the tendency to study ever-larger macromolecules and complexes. Further improvements in methods and instrumentation suited to growing larger crystals are therefore necessary for the use of NMX to expand.
In this work, we introduce rational strategies and a crystal growth bench (OptiCrys) developed in our laboratory that combines real-time observation through a microscope-mounted video camera with precise automated control of crystallization solutions (e.g., precipitant concentration, pH, additive, temperature). We then demonstrate how this control of temperature and chemical composition facilitates the search for optimal crystallization conditions using model soluble proteins. Thorough knowledge of the crystallization phase diagram is crucial for selecting the starting position and the kinetic path for any crystallization experiment. We show how a rational approach can control the size and number of crystals generated based on knowledge of multidimensional phase diagrams.

Structural studies of biomacromolecules by crystallography require high-quality crystals. Here we demonstrate a protocol that can be used by OptiCrys (a fully automated instrument developed in our lab) and/or microdialysis buttons for growing large high-quality crystals based on knowledge of the crystallization phase diagram.

Ottimizzazione della crescita del cristallo per la cristallografia macromolecolare neutronica

The use of neutron macromolecular crystallography (NMX) is expanding rapidly with most structures determined in the last decade thanks to new NMX ...

Simultaneous Live Imaging of Multiple Insect Embryos in Sample Chamber-Based Light Sheet Fluorescence Microscopes

Light sheet-based fluorescence microscopy offers efficient solutions to study complex processes on multiple biologically relevant scales. Sample chamber-based setups, which are specifically designed to preserve the three-dimensional integrity of the specimen and usually feature sample rotation, are the best choice in developmental biology. For instance, they have been used to document the entire embryonic morphogenesis of the fruit fly Drosophila melanogaster and the red flour beetle Tribolium castaneum. However, many available live imaging protocols provide only experimental frameworks for single embryos. Especially for comparative studies, such approaches are inconvenient, since sequentially imaged specimens are affected by ambient variance. Further, this limits the number of specimens that can be assayed within a given time. We provide an experimental framework for simultaneous live imaging that increases the throughput in sample chamber-based setups and thus ensures&#160;similar ambient conditions for all specimens. Firstly, we provide a calibration guideline for light sheet fluorescence microscopes. Secondly, we propose a mounting method for multiple embryos that is compatible with sample rotation. Thirdly, we provide exemplary three-dimensional live imaging datasets of Drosophila, for which we juxtapose three transgenic lines with fluorescently labeled nuclei, as well as of Tribolium, for which we compare the performance of three transgenic sublines that carry the same transgene, but at different genomic locations. Our protocol is specifically designed for comparative studies as it pro-actively addresses ambient variance, which is always present in sequential live imaging. This is especially important for quantitative analyses and characterization of aberrational phenotypes, which result e.g., from knockout experiments. Further, it increases the overall throughput, which is highly convenient when access to light sheet&#160;fluorescence microscopes is limited. Finally, the proposed mounting method can be adapted for other insect species and further model organisms, e.g., zebrafish, with basically no optimization effort.

Light sheet-based fluorescence microscopy is the most valuable tool in developmental biology. A major issue in comparative studies is ambient variance. Our protocol describes an experimental framework for simultaneous live imaging of multiple specimens and, therefore, addresses this issue pro-actively.

Imaging live simultaneo di più embrioni di insetti nei microscopi a fluorescenza a fogli di luce a camera campione

Light sheet-based fluorescence microscopy offers efficient solutions to study complex processes on multiple biologically relevant scales. Sample ...

Studio del meccanismo di trasporto dello zinco nelle cellule di mammifero con il saggio FluoZin-3

Characterizing Mammalian Zinc Transporters Using an In Vitro Zinc Transport Assay

Transition metals such as Zn2+ ions must be tightly regulated due to their cellular toxicity. Previously, the activity of Zn2+ transporters was measured indirectly by determining the expression level of the transporter under different concentrations of Zn2+. This was done by utilizing immunohistochemistry, measuring mRNA in the tissue, or determining the cellular Zn2+ levels. With the development of intracellular Zn2+ sensors, the activities of zinc transporters are currently primarily determined by correlating changes in intracellular Zn2+, detected using fluorescent probes, with the expression of the Zn2+ transporters. However, even today, only a few labs monitor dynamic changes in intracellular Zn2+ and use it to measure the activity of zinc transporters directly. Part of the problem is that out of the 10 zinc transporters of the ZnT family, except for ZnT10 (transports manganese), only zinc transporter 1 (ZnT1) is localized at the plasma membrane. Therefore, linking the transport activity to changes in the intracellular Zn2+ concentration is hard. This article describes a direct way to determine the zinc transport kinetics using an assay based on a zinc-specific fluorescent dye, FluoZin-3. This dye is loaded into mammalian cells in its ester form and then trapped in the cytosol due to cellular di-esterase activity. The cells are loaded with Zn2+ by utilizing the Zn2+ ionophore pyrithione. The ZnT1 activity is assessed from the linear part of the reduction in fluorescence following the cell washout. The fluorescence measured at an excitation of 470 nm and emission of 520 nm is proportional to the free intracellular Zn2+. Selecting the cells expressing ZnT1 tagged with the mCherry fluorophore allows for monitoring only the cells expressing the transporter. This assay is used to investigate the contribution of different domains of ZnT1 protein to the transport mechanism of human ZnT1, a eukaryotic transmembrane protein that extrudes excess zinc from the cell.

Autore in primo piano: Esplorare la regolazione cellulare dello zinco attraverso la funzionalità ZnT1 

Zinc transport has proven challenging to measure due to the weak causal links to protein function and the low temporal resolution. This protocol describes a method for monitoring, with high temporal resolution, Zn2+ extrusion from living cells by utilizing a Zn2+ sensitive fluorescent dye, thus providing a direct measure of Zn2+ efflux.

Caratterizzazione dei trasportatori di zinco nei mammiferi mediante un saggio di trasporto dello zinco in vitro

Transition metals such as Zn2+ ions must be tightly regulated due to their cellular toxicity. Previously, the activity of Zn2+ transporters was measured ...