Unsere Arbeit wird durch Zuschüsse von NIH / NIGMS, NSF, USDA / NIFA und BARD zu VC unterstützt.

Hintergrund Symplastisch Transport von Makromolekülen durch Anlage interzellulären Verbindungen, die Plasmodesmen, ist von Interesse für viele Pflanzen-Pathologen und Biologen. Zum Beispiel sind mehrere virale Proteine ​​bekannt, plasmodesmal Größenausschlusschromatographie Grenzen zu regulieren, damit virale Bewegung 1-3. Auch sind einige endogene Proteine, darunter wichtige Entwicklungs-Regulatoren, angenommen von Zelle zu Zelle bewegen, vermutlich durch Plasmodesmen, nicht-Zell-autonome 4 Funktionstasten. So ist eine zuverlässige Methode zur Identifizierung und Visualisierung von makromolekularen Transport zwischen Pflanzenzellen sehr gefragt. 1) wachsen Zielpflanzen Für hohe Transformationseffizienz, sollten gesunde, robuste Pflanzen verwendet werden. 1. Arabidopsis-Pflanzen Wachsen ein Arabidopsis-Pflanze auf Pro-Mix BX in einem Topf (10 cm x 10 cm x 10 cm) in einer Umgebung, kontrollierten Kammer mit einer kurzen Photoperiode (8 Std. von 130-150 uE m -2 s -1 Licht bei 23 ° C/16 h Dunkelheit bei 20 ° C) und 40-65% relativer Luftfeuchtigkeit für 6 bis 8 Wochen 5. Düngen Sie sie gelegentlich mit handelsüblichen Produkten wie beschrieben 5. Blätter mit der Größe von mehr als 15 mm x 35 mm (der Längenmessung umfasst Blattstiel) sind für die Experimente ausgewählt. 2. N. benthamiana und N. tabacum Wachsen einer Pflanze auf Pro-Mix BX in einem Topf (20 cm x 20 cm x 20 cm) in einer Umgebung, kontrollierten Kammer mit einer langen Photoperiode (16 hr von 130-150 uE m -2 s -1 Licht bei 23 ° C / 8 h Dunkelheit bei 20 ° C) und 40-65% relativer Luftfeuchtigkeit für 7 bis 10 Wochen. Düngen Sie sie gelegentlich mit handelsüblichen Produkten wie beschreiben. Blätter mit einer Größe größer als 50 mm x 70 mm für N. benthamiana oder 100 mm x 125 mm für N. tabacum (diese Länge Messungen umfassen nicht Blattstiel) sind für die Experimente ausgewählt. 2) Herstellung der Gene Gun Cartridge mit DNA-beschichteten Gold-Mikropartikel Das Protokoll für diesen experimentellen Schritt wurde im Detail bereits 6 beschrieben. Es ist sehr wichtig, gut gereinigte Plasmid-DNA bei hohen Konzentrationen (~ 1 ug / ul) auf den höchsten Wirkungsgrad bei der die Leichtigkeit der konfokalen Mikroskopie Analyse in den späteren Phasen des Experiments zu erhalten verwenden. Für diesen Test ist es wichtig festzustellen, dass die vorbereitete Kartusche nicht verwandeln zwei oder mehr benachbarte Zellen gleichzeitig mit hoher Frequenz, weil die Zahl der Zellen assoziieren mit einem Fluoreszenz-Signal-Cluster als ein Indikator für das Ausmaß der symplastisch Verkehr (dh verwendet wird , eine einzelne Zelle mit dem Signal zeigt an, keine Bewegung, während ein multicell Signal-Cluster zeigt Bewegung). Die Qualität der einzelnen Patronen kann durch die Analyse der Expression des Proteins 16-20 Stunden post Beschuss geprüft werden. Unser Protokoll 6 erzeugt Patronen, die multicell Ausdruck Cluster nur in &lt;3% aller Ausdruck Ereignisse in diesem Zeitraum, so geeignet für dieses Experiment ergeben. 3) Biolistic Lieferung von DNA-beschichteten Mikropartikeln <ol><li> Entfernen Sie die Blätter der gleichen Entwicklungsstufe (dh mit gleicher Größe und gleichem Alter, siehe Schritt 1) ​​mit einer scharfen Rasierklinge und sofort legen Sie sie mit der abaxialen Seiten nach oben auf eine flache Oberfläche aus Styropor. Die abaxialen Seite des Blattes ist ein besseres Substrat für Bombardements aufgrund seiner geringeren Dichte Trichom und dünner Cuticula. Arabidopsis Blättern, die aufgrund ihrer relativ geringen Größe, mit einem Stück Fenster Siebgewebe sollte abgedeckt werden, und das Netz dann mit Reißzwecken befestigt die Styropor-Oberfläche. Die Aufrechterhaltung Blätter flach erhöht die Effizienz des Teilchens Lieferung und minimiert die Schädigung des Gewebes während microbombardment. </li><li> Setzen Sie die Patrone mit DNA-beschichteten Mikropartikeln (hergestellt in Schritt 1) ​​in der Pistole. Für Arabidopsis, ist der Shooting bei einem Druck von 80-110 psi für 1-um Mikropartikel, und 140-160 psi für 0,6-um Mikropartikel durchgeführt. Für N. benthamiana und Tabak, ist der Shooting bei einem Druck von 100-120 bar für 1-um Mikropartikel, und 160-180 psi für 0,6-um Mikropartikel durchgeführt. Für Arabidopsis, wir verwenden normalerweise eine Patrone pro Blatt, weil jedes Blatt hat genug Fläche nur für eine Aufnahme, die Mikropartikel erstreckt sich über eine Fläche von 10-12 mm im Durchmesser. Bei größeren N. benthamiana und Tabakblättern, mehrere Bombardierungen der selben Blatt sind möglich, jedoch müssen sie bei der symmetrischen Positionen auf jeder Seite der Mittelrippe, die Blattflächen auf derselben Entwicklungsstufe Ziel (siehe Diskussion) durchgeführt werden. </li><li> Entfernen Sie die Blätter aus dem Styropor Oberfläche und sie inicht eine Petrischale auf 3 Schichten nassen Whatman Filterpapier, versiegeln Sie die Petrischale mit Parafilm, und inkubieren Sie bei Raumtemperatur für 36-48 Stunden, um die Expression der Transgene geliefert und das Potenzial von Zelle zu Zelle Bewegung ihrer Eiweiss-Produkte ermöglichen . </li></ol> 4) Imaging of Protein Expression Das Fluoreszenzsignal des transient exprimiert markierte Proteine ​​visualisiert durch konfokale Mikroskopie. Es sollte darauf geachtet, um eine optimale Mikroskopie Einstellungen für die Erkennung der jeweils getesteten Protein zu finden. Zum Beispiel Proteine, die begrenzte intrazelluläre Akkumulation Show mit schwachen Signalintensitäten, wie die plasmodesmal Lokalisation des Tabak-Mosaik-Virus Bewegung Protein (TMV MP) 1-3,6, sollten unter einem 40x Objektiv, das eine höhere Auflösung und bietet beobachtet werden Empfindlichkeit, während Proteine, die zytoplasmatische Verteilung zeigen, mit starken Signalintensitäten, wie freie YFP, kann unter einem 10x Objektiv mit konfokaler Zoom-Funktion für eine schnellere Bildgebung (siehe Abbildung 1) visualisiert. Symplastisch Transport aus dem Auftreten von mehrzelligen Cluster, dass die Fluoreszenz-Signal enthalten abgeleitet. Die Zahl solcher Cluster und die Anzahl der Zellen in jedem Cluster ist bezeichnend für das Ausmaß der Zelle zu Zelle zu transportieren. Um zuverlässige Daten, sollte mindestens 100 Ausdruck Cluster pro experimentelles System erfasst werden. Zum Beispiel sollte, wenn die Zelle zu Zelle Bewegung eines Proteins ist in zwei unterschiedlichen genetischen Hintergründen (zB Wildtyp und transgenen Pflanzen), mit einem Gesamtwert von 200 Expressions-Clustern verglichen aufgezeichnet werden. Wichtig ist, dass Versuche, sollten die Ergebnisse, die miteinander verglichen werden, sind gleichzeitig durchgeführt werden. 5. Repräsentative Ergebnisse Die folgende Abbildung zeigt repräsentative Experimente zum Nachweis von symplastisch Transport von fluoreszenzmarkierten Proteinen. Die Abbildungen A und B zeigen die typische konfokale Bilder, die folgenden microbombardment einer N. gewonnen werden benthamiana Blatt mit einem TMV MP-YFP-exprimierenden konstruieren. In Panel A, symplastisch Bewegung der TMV MP-YFP wird basierend auf dem Aussehen der multicell Cluster der YFP-Signal beobachtet. Nicht alle transient exprimiert TMV MP-YFP ist in der Lage sich zu bewegen, wie Single-Cell-Signal in einigen microbombardments (Panel B) zeigt. Statistisch gesehen, in &lt;40% der gezählten Signal-Cluster ist TMV MP-YFP nicht zwischen den Zellen während bewegen sich in&gt; 60% der Cluster, bewegt sich das Protein zwischen 2-5 Zellen, wobei die beiden Zellen verteilt die häufigste (ca. ~ 50% der Fälle) (Abbildung 1C). Die Proteine ​​mit relativ kleinen Molekülgröße, ohne angeborene Bewegung Aktivität kann durch PD diffuse, um von Zelle zu Zelle bewegen. Zum Beispiel, breitet sich kostenlos YFP oder 1xYFP (ca. 27 kDa, Panel D), zwischen mehreren Zellen in 30% der gezählten Cluster (Panels C). Diese unspezifische Diffusion nicht für eine translationale YFP Dimmer oder 2xYFP (54 kDa, Panel E), die in der Größe vergleichbar ist, TMV MP-YFP-Fusionsprotein (57 kDa), und die vollständig zellautonome auftreten (Abb. 1C). <img src="/files/ftp_upload/2208/2208fig1.jpg" alt="Abbildung 1" /> Abbildung 1. Typische Ergebnisse aus der symplastisch Transport-Assay in N. erhalten benthamiana Blattgewebe. (A, B) Visualisierung von TMV MP-YFP. (C) Quantifizierung der Signal-Cluster. 1xYFP und 2xYFP, frei YFP und translationale YFP Dimer bzw.. (D) Visualisierung von 1xYFP. (E) Visualisierung von 2xYFP. In Aufnahmen zeigen die linken Panels der YFP-Signal und das Recht Tafeln zeigen fusionierten Bilder von YFP (in grün) und Chloroplasten-Autofluoreszenz (in weiß) Signale. Die Bilder werden einzelne konfokale Schnitte. Sternchen in den Aufnahmen zeigen die Epidermiszellen zeigt YFP-Signal. Bars = 50 um.

<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. 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Der Schlüssel für den Erfolg der symplastisch Transport-Assay ist eine hohe Transformationseffizienz, die Produktion von statistisch signifikant und leicht nachweisbaren Signal-Cluster ermöglicht zu erhalten. Dies kann erreicht werden mit den Blättern von gesunden, robusten Pflanzen geerntet, und die Vorbereitung Goldpartikel durch eine reine und konzentrierte DNA-Präparation beschichtet werden. Mit den Blättern an der gleichen Wachstumsphase ist auch entscheidend für den Test Zuverlässigkeit. Plasmodesmal Blende ist bekannt, differentiell reguliert werden, je nach Entwicklungsstadium des Gewebes 7-11. Blättern vieler Pflanzenarten entwickeln basipetal, von der Spitze zur Basis, mit der apikalen Teil des Blattes wird reifer als ihre basalen Teil 12. So sollte nicht nur das Entwicklungsstadium der Blätter (in der Regel durch ihre Größe und Position auf dem Schaft reflektiert) für jede Gruppe von ausgewählten Experimente identisch sein, aber das Blatt Bereichen microbombardment gezielte sollte an der identischen Positionen befinden. Einige frühere Studien haben zellautonome Marker, wie das endoplasmatische Retikulum-band GFP (erGFP) 11, eingesetzt werden, um zunächst transformierten Zellen von denjenigen, denen die getesteten Protein wurde von symplastisch Transportmittel bewegt zu unterscheiden. Allerdings ergab eine spätere Studie, dass die gleichzeitige Expression von einigen Nicht-Zell-autonome Proteine ​​mit erGFP könnte seine Zelle zu Zelle Bewegungsrichtung 13 zu induzieren, Infragestellung der Zuverlässigkeit der erGFP als erste Transformation Marker und eine erhebliche Erhöhung der Schwierigkeit bei der Interpretation der Daten aus wie Koexpression Experimente. So ziehen wir es vermeiden, die Einführung Ausdruck eines anderen Proteins in unserer Bewegung Assay, und stattdessen verlassen sich auf die statistische Analyse von Signal-Cluster-Nummern.

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

Hier stellen wir ein einfaches und schnelles Protokoll zu erkennen und zu beurteilen, das Ausmaß der Zell-Zell-makromolekularen Transport in planta. In diesem Protokoll wird ein fluoreszenzmarkierten-Protein von Interesse vorübergehend in Pflanzengewebe folgenden biolistischen Auslieferung der kodierenden DNA-Konstrukt zum Ausdruck gebracht. Die intra-und interzelluläre Verteilung der markierte Protein wird dann durch konfokale Mikroskopie analysiert. Wir beschreiben diese Technik im Detail und bietet Schritt-für-Schritt-Protokolle Assay und der Beurteilung von symplastisch Transport von Proteinen in drei Pflanzenarten, Arabidopsis thaliana, Nicotiana benthamiana und N. tabacum (Tabak).

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

Makromolekulare Handel zwischen Pflanzenzellen können durch transiente Expression eines Fluoreszenz-markierten Proteins von Interesse und die Analyse ihrer intra-und interzelluläre Verteilung durch konfokale Mikroskopie beurteilt werden.

Ein Cell-to-cell Makromolekulare Transport Assay In Planta Verwendung Biolistic Bombardment

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

Nanyang Technological University

Research

JoVE Journal

Biology

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

11.8K Aufrufe.  State University of New York at Stony Brook. Makromolekulare Handel zwischen Pflanzenzellen können durch transiente Expression eines Fluoreszenz-markierten Proteins von Interesse und die Analyse ihrer intra-und interzelluläre Verteilung durch konfokale Mikroskopie beurteilt werden.

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

Preparation of Gene Gun Bullets and Biolistic Transfection of Neurons in Slice Culture

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed protocol for biolistic transfection of rat hippocampal slices, from the initial preparation of DNA coated bullets to the final shooting of the organotypic slice cultures using a gene gun. Gene gun transfection is an efficient and easy means of transfecting neurons and is especially useful for fluorescently labeling a small subset of cells in tissue slice. In this video, we first outline the steps required to coat gold particles with DNA. We next demonstrate how to line the inside of plastic tubing with the gold/DNA bullets, and how to cut this tubing to obtain the plastic cartridges for loading into the gene gun. Finally, we perform biolistic transfection of rat hippocampal slice cultures, demonstrating handling of the Bio-Rad Helios gene gun, and offering trouble shooting advice to obtain healthy and optimally transfected tissue slices.  

We describe a method for preparing DNA coated gold bullets and demonstrate the use of such bullets to biolistically transfect neurons in cultured hippocampal slices.

Vorbereitung der Gene Gun und Aufzählungszeichen Biolistic Transfektion von Neuronen in Scheiben Kultur

Biolistic transfection is a physical means of transfecting cells by bombarding tissue with high velocity DNA coated particles. We provide a detailed ...

Forschung

Biologie

Window on a Microworld: Simple Microfluidic Systems for Studying Microbial Transport in Porous Media

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in the environment, as well as directly for the transmission of pathogens to drinking water supplies. Natural porous media is composed of an intricate physical topology, varied surface chemistries, dynamic gradients of nutrients and electron acceptors, and a patchy distribution of microbes. These features vary substantially over a length scale of microns, making the results of macro-scale investigations of microbial transport difficult to interpret, and the validation of mechanistic models challenging. Here we demonstrate how simple microfluidic devices can be used to visualize microbial interactions with micro-structured habitats, to identify key processes influencing the observed phenomena, and to systematically validate predictive models. Simple, easy-to-use flow cells were constructed out of the transparent, biocompatible and oxygen-permeable material poly(dimethyl siloxane). Standard methods of photolithography were used to make micro-structured masters, and replica molding was used to cast micro-structured flow cells from the masters. The physical design of the flow cell chamber is adaptable to the experimental requirements: microchannels can vary from simple linear connections to complex topologies with feature sizes as small as 2 &mu;m. Our modular EcoChip flow cell array features dozens of identical chambers and flow control by a gravity-driven flow module. We demonstrate that through use of EcoChip devices, physical structures and pressure heads can be held constant or varied systematically while the influence of surface chemistry, fluid properties, or the characteristics of the microbial population is investigated. Through transport experiments using a non-pathogenic, green fluorescent protein-expressing Vibrio bacterial strain, we illustrate the importance of habitat structure, flow conditions, and inoculums size on fundamental transport phenomena, and with real-time particle-scale observations, demonstrate that microfluidics offer a compelling view of a hidden world.

Microfluidic devices can be used to visualize complex natural processes in real time and at the appropriate physical scales. We have developed a simple microfluidic device that mimics key features of natural porous media for studying growth and transport of bacteria in the subsurface.

Fenster an einem Microworld: Einfache mikrofluidische Systeme für Studium Mikrobielle Transport in porösen Medien

Microbial growth and transport in porous media have important implications for the quality of groundwater and surface water, the recycling of nutrients in ...

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.

Erzeugung von transgenen C. elegans Nach 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 ...

Agrobacterium-Mediated Virus-Induced Gene Silencing Assay In Cotton

Cotton (Gossypium hirsutum) is one of the most important crops worldwide. Considerable efforts have been made on molecular breeding of new varieties. The large-scale gene functional analysis in cotton has been lagged behind most of the modern plant species, likely due to its large size of genome, gene duplication and polyploidy, long growth cycle and recalcitrance to genetic transformation1. To facilitate high throughput functional genetic/genomic study in cotton, we attempt to develop rapid and efficient transient assays to assess cotton gene functions.
Virus-Induced Gene Silencing (VIGS) is a powerful technique that was developed based on the host Post-Transcriptional Gene Silencing (PTGS) to repress viral proliferation2,3. Agrobacterium-mediated VIGS has been successfully applied in a wide range of dicots species such as Solanaceae, Arabidopsis and legume species, and monocots species including barley, wheat and maize, for various functional genomic studies3,4. As this rapid and efficient approach avoids plant transformation and overcomes functional redundancy, it is particularly attractive and suitable for functional genomic study in crop species like cotton not amenable for transformation.
In this study, we report the detailed protocol of Agrobacterium-mediated VIGS system in cotton. Among the several viral VIGS vectors, the tobacco rattle virus (TRV) invades a wide range of hosts and is able to spread vigorously throughout the entire plant yet produce mild symptoms on the hosts5. To monitor the silencing efficiency, GrCLA1, a homolog gene of Arabidopsis Cloroplastos alterados 1 gene (AtCLA1) in cotton, has been cloned and inserted into the VIGS binary vector pYL156. CLA1 gene is involved in chloroplast development6, and previous studies have shown that loss-of-function of AtCLA1 resulted in an albino phenotype on true leaves7, providing an excellent visual marker for silencing efficiency. At approximately two weeks post Agrobacterium infiltration, the albino phenotype started to appear on the true leaves, with 100% silencing efficiency in all replicated experiments. The silencing of endogenous gene expression was also confirmed by RT-PCR analysis. Significantly, silencing could potently occur in all the cultivars we tested, including various commercially grown varieties in Texas. This rapid and efficient Agrobacterium-mediated VIGS assay provides a very powerful tool for rapid large-scale analysis of gene functions at genome-wide level in cotton.

We present the detailed protocol for Agrobacterium-mediated virus-induced gene silencing (VIGS) assay in cotton. The tobacco rattle virus (TRV)-derived VIGS vectors were deployed to induce RNA silencing of cotton GrCLA1, Cloroplastos alterados 1 gene. The albino phenotype caused by silencing GrCLA1 was observed at the seedling stage within 2 weeks after inoculation.

Agrobacterium-vermittelte Virus-induced gene silencing Assay In Cotton

Cotton (Gossypium hirsutum) is one of the most important crops worldwide. Considerable efforts have been made on molecular breeding of new varieties.  The ...

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.

In-vitro-Analyse der PDZ-abhängigen CFTR Makromolekulare Signalkomplexe

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.

Die Züchtung<em&gt; Caenorhabditis elegans</em &gt; In Axenic Flüssige Medien und Erstellung von transgenen Worms durch Mikropartikelbeschuss

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 High Content Analyse Unter Verwendung Automatische Fluorescence Lifetime Imaging Mikroskopie

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

Methods to Study Epithelial Transport Protein Function and Expression in Native Intestine and Caco-2 Cells Grown in 3D

The intestinal epithelium has important transport and barrier functions that play key roles in normal physiological functions of the body while providing a barrier to foreign particles. Impaired epithelial transport (ion, nutrient, or drugs) has been associated with many diseases and can have consequences that extend beyond the normal physiological functions of the transporters, such as by influencing epithelial integrity and the gut microbiome. Understanding the function and regulation of transport proteins is critical for the development of improved therapeutic interventions. The biggest challenge in the study of epithelial transport is developing a suitable model system that recapitulates important features of the native intestinal epithelial cells. Several in vitro cell culture models, such as Caco-2, T-84, and HT-29-Cl.19A cells are typically used in epithelial transport research. These cell lines represent a reductionist approach to modeling the epithelium and have been used in many mechanistic studies, including their examination of epithelial-microbial interactions. However, cell monolayers do not accurately reflect cell-cell interactions and the in vivo microenvironment. Cells grown in 3D have shown to be promising models for drug permeability studies. We show that Caco-2 cells in 3D can be used to study epithelial transporters. It is also important that studies in Caco-2 cells are complemented with other models to rule out cell specific effects and to take into account the complexity of the native intestine. Several methods have been previously used to assess the functionality of transporters, such as everted sac and uptake in isolated epithelial cells or in isolated plasma membrane vesicles. Taking into consideration the challenges in the field with respect to models and the measurement of transport function, we demonstrate here a protocol to grow Caco-2 cells in 3D and describe the use of an Ussing chamber as an effective approach to measure serotonin transport, such as in intact polarized intestinal epithelia.

We describe simple methods to study the regulation of intestinal serotonin transporter (SERT) function and expression using an in vitro cell culture model of Caco-2 cells grown in 3D&#160;and an ex vivo model of mouse intestines. These methods are applicable to the study of other epithelial transporters.

Methoden Epithelial Transportprotein Funktion und Expression in Mutterdarm und Caco-2-Zellen gezüchtet in 3D zu studieren

The intestinal epithelium has important transport and barrier functions that play key roles in normal physiological functions of the body while providing ...

Quantifying Spatiotemporal Parameters of Cellular Exocytosis in Micropatterned Cells

Live imaging of the pHluorin tagged Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (v-SNARE) Vesicle-associated membrane protein 7 (VAMP7) by total internal reflection fluorescence microscopy (TIRFM) is a straightforward way to explore secretion from the lysosomal compartment. Taking advantage of cell culture on micropatterned surfaces to normalize cell shape, a variety of statistical tools were employed to perform a spatial analysis of secretory patterns. Using Ripley&#8217;s K function and a statistical test based on the nearest neighbor distance (NND), we confirmed that secretion from lysosomes is not a random process but shows significant clustering. Of note, our analysis revealed that exocytosis events are also clustered in nonadhesion areas, indicating that adhesion molecules are not the only structures that can induce secretory hot spots at the plasma membrane. Still, we found that cell adhesion enhances clustering. In addition to precisely defined adhesive and nonadhesive areas, the circular geometry of these micropatterns allows the use of polar coordinates, simplifying analyses. We used Kernel Density Estimation (KDE) and the cumulative distribution function on polar coordinates of exocytosis events to identify enriched areas of exocytosis. In ring-shaped micropattern cells, clustering occurred at the border between the adhesive and nonadhesive areas. Our analysis illustrates how statistical tools can be employed to investigate spatial distributions of diverse biological processes.

Live imaging of lysosomal exocytosis on micropatterned cells allows a spatial quantification of this process. Morphology normalization using micropatterns is an outstanding tool to uncover general rules about the spatial distribution of cellular processes.

Quantifizierung der raumzeitlichen Parameter der zellulären Exozytose in mikrogemusterten Zellen

Live imaging of the pHluorin tagged Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (v-SNARE) Vesicle-associated membrane protein 7 ...

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.