I am grateful to Dr. Masaru Fujimoto for his technical suggestions for VAEM. I am also grateful to Prof. Koh Iba and Dr. Mimi Hashimoto-Sugimoto for providing GFP-PATROL1 transgenic plants, and discussions about PATROL1. I thank Prof. Seiichiro Hasezawa for his continuing support of my work. This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI grant number 25711017.

1. Herstellung von Jungpflanzen <ol><li> Sterilisieren Sie die Samen. <ol><li> Vorbereitung der Sterilisationslösung durch Zugabe von 500 &amp; mgr; l NaClO (verfügbares Chlor: 5,0%) und 1 ul 10% Triton X-100 und 500 &amp; mgr; l sterilem Wasser. </li><li> Platz ca. 10 transgenen A. thaliana Samen tragenden GFP-PATROL1 8 in ein 1,5-ml-Tube. </li><li> 1 ml 70% Ethanol-Lösung, und gut mischen durch Invertieren fünfmal. Lassen Sie für 1 min. </li><li> Beobachten die Samen zu Boden sinken, der Röhre. In einem sauberen Sterilbank, entfernen Sie vorsichtig die 70% Ethanol mit einer Mikropipette, und fügen Sie 1 ml Sterilisationslösung. Gut mischen durch Invertieren fünf Mal und lassen Sie für 5 min. </li><li> Die Samen zu waschen. Arbeiten noch unter aseptischen Bedingungen auf einer sauberen Werkbank, entfernen Sie vorsichtig die Lösung mit einer Mikropipette, und fügen Sie 1 ml sterilem Wasser. Wiederholen Sie dies fünf Mal. Die sterilisierten Samen können in sterilem Wasser bei 4 ° C für 2 Tage aufbewahrt werden. </li></ol></li><li> Alsow den sterilisierten Samen auf einem 0,5% Gellangummi verfestigt 1/2 Murashige und Skoog Medium Platte (pH 5,8) 9. Band der Deckel auf die Platte unter Verwendung von zwei Schichten von chirurgischem Band. </li><li> Inkubieren der Platte in der Dunkelheit bei 4 ° C mit einem kalten Speicherraum, O / N. </li><li> Übertragen Sie die Platte in eine Wachstumskammer bei 23,5 ° C mit einer 12-Stunden / 12-Stunden-Hell-Dunkel-Zyklus unter Verwendung von 100 &amp; mgr; mol m -2 s -1 weiße Lichter gesetzt, und Inkubation für 7 Tage. Sämlinge mit Keimblättern von etwa 1 mm lang kann dann geerntet werden. </li></ol> 2. Sky Tropfen Montage der Cotyledon Proben HINWEIS: Ein wichtiger Faktor bei der Probenvorbereitung für vaem Beobachtung wird die Vermeidung der Einschluss von Luftblasen zwischen der Probe und dem Deckglas. Bubbles die Bildqualität von vaem erheblich reduzieren, indem Unterschiede im Brechungsindex. Eine einfache Methode, die wir &quot;Himmel Drop&quot; genannt Montage kann verwendet werden, um Blasen zu vermeidenzwischen der A. thaliana Keimblätter und das Deckglas. Dieses ist unmittelbar vor der Beobachtung durchgeführt werden. <ol><li> Werden 30 ul Basalpuffer [5 mM 2- (N-Morpholino) ethansulfonsäure-Tris (MES-Tris) bei pH 6,5, 50 mM KCl, 100 uM CaCl &amp; sub2;] auf dem Zentrum eines Glasobjektträgers (Größe: 76 × 26 mm, Dicke: 1,0 bis 1,2 mm). </li><li> Entfernen Sie ein Keimblatt aus einem 7-Tage-alten Keimling mit Präparierscheren. Schwimmer den Kotyledonen mit der Beobachtungsseite nach oben auf dem Basalpuffer Abfall (Abbildung 1, Schritt 1). </li><li> Werden 30 ul Basalpuffer auf der Mitte eines Deckglases (Größe: 18 × 18 mm, Dicke: 0,12-0,17 mm) (Abbildung 1, Schritt 2). Drehen Sie das Deckglas auf den Kopf sanft. Die Oberflächenspannung wird die Puffertropfen herunterfällt. Halten Sie das Deckglas mit einer Pinzette an einer Kante. Platzieren der gegenüberliegenden Kante auf dem Glasträger, so dass der Puffer Abfall ist etwa über dem Keimblatt. </li><li>Mit der Kante des Deckglases noch auf der Folie, und immer noch das gegenüberliegende Kante mit einer Pinzette, passen die Position des Pufferabfall unter dem Deckglas, so daß es unmittelbar oberhalb des Keimblattprobe (1, Schritt 3). Lassen Sie das Deckglas. Montieren Sie einen Tropfen auf die Probe, was zu einem Präparat ohne Luftblasen. </li><li> Wischen Sie überschüssiges Puffer mit fusselfreien Gewebe. Beobachten Sie sofort die Vorbereitung (siehe Schritt 3). HINWEIS: Es ist nicht notwendig, um die Proben zu versiegeln. </li></ol> 3. vaem Beobachtung und Film-Übernahme HINWEIS: Ein invertiertes Mikroskop ist mit einem TIRF Einheit und einer TIRF Objektivlinse mit einer numerischen Apertur von 1,49 ausgestattet: Die TIRF Mikroskopsystem 9 in der vorliegenden Studie verwendet wird wie folgt beschrieben. Für computergestützte Steuerung der Lasereintrittswinkel wird ein Steuerfeld verwendet. Grün fluoreszierendes Protein (GFP) erregt wird mit einer 488 nm optisch gepumpte Halbleiterlaser und ter Fluoreszenz wird durch einen 510-550 nm Bandpassfilters erfasst wird, um die Autofluoreszenz von Chloroplasten verhindern. Die gemessene Maximalwert des Faserausgangsleistung von 13,0 bis 13,5 mW. Für den Nachweis, eine Elektronenvervielfachungs charge-coupled device (EM-CCD) Kamera-Kopf-System und ein C-Mount-Kamera Vergrößerungsänderungseinheit verwendet. <ol><li> Kalibrieren der Laser Zentrierung und Fokussierung entsprechend den Anweisungen des Herstellers. HINWEIS: Dieser Schritt ist entscheidend für eine präzise vaem Beobachtungen. Es wird dringend empfohlen, dass regelmäßige Kontrollen der Laserpfad Bereinigungsverfahren, die zu Ihrem Mikroskop durchgeführt werden. <ol><li> Bestimmen Sie die zentrale Lage mit einer Objektivlinse freie Lichtpfad an der Decke der Mikroskopie Raum beleuchtet. Um die zentrale Position zu markieren, setzen Sie einen farbigen Kreis Dichtung an der Decke (Abbildung 2, Stufe 1, 2). </li><li> Beleuchten die Decke mit einer Objektivlinse (Abbildung 2, Schritt 3, 4). Bewegen Sie den illuminated Region in die Mittelstellung (Abbildung 2, Schritt 5). Fokus des Lasers (Abbildung 2, Schritt 6). Feinabstimmung der Position des fokussierten Laserstrahls auf die Mitte (Abbildung 2, Schritt 7). </li></ol></li><li> Legen Sie ein Objekt auf den Tisch des Mikroskops und wählen Sie Zellen für die Beobachtung mit Hellfeldbeleuchtung. </li><li> Überprüfen Sie, dass das fluoreszierende Protein in den Zellen beobachtet werden, und stellen Sie die z-Achse Position an der Zelloberfläche unter Verwendung von Epifluoreszenz-Beleuchtung (3A). </li><li> Führen vaem Beobachtungen. <ol><li> Neigen Sie den Eintrittswinkel des Laserstrahls allmählich mit der Controller-Box. Zur gleichen Zeit, zu überwachen das Live-Bild sorgfältig. Zunächst wird das Bild unscharf werden (3B). </li><li> Da die Laserwinkel zunimmt, wird die vaem Bild weniger unscharf werden, was schließlich eine klare Bild (3C und D). An dieser Stelle aufhören Increasingen die Laserwinkel. Wenn das Fluoreszenz-Signal verloren gegangen ist, zu verringern, um einen flacheren Winkel. </li><li> Feinabstimmung der Lasereintrittswinkel, um ein besseres Bild zu erhalten. Feinabstimmung der Z-Achsen-Position kann auch das Bild zu verbessern. Passen Sie bei Bedarf die optischen Parameter (Laserleistung, Wellenlänge und Filtersatz) und die Bildsensorparameter [Bildgröße, Belichtungszeit, Verstärkung, Digitizer und Elektronen-Multiplikation (EM) Verstärkung]. HINWEIS: In dem oben beschriebenen Fall der TIRF Mikroskopausrüstung, sind wie folgt repräsentativen Parametern. Vergrößerung der Linse direkt vor der Kamera: 2X; Laserleistung: 1,0 mW; Bildgröße: 512 x 512 Pixel; Belichtungszeit: 100 ms; Gewinnen: 5 x; Digitizer: 11 MHz; und EM-Gewinn: 100. </li></ol></li><li> Erwerben Sie einen Film als eine mehrseitige TIFF-Image-Datei mit der kommerziellen Mikroskop-Software. Hierbei ist von GFP-markierten Punkte blinkt auf der Oberfläche der Spaltöffnungszellen der Film. HINWEIS: Vertreter Bildaufnahme Bedingungen sind wie folTiefen. Erfassungsmodus: Strom in den RAM; Anzahl der Frames: 600; und mehrseitige TIFF-Dateigröße: ~ 302 MB. </li></ol> 4. Kymograph Analyse zur Quantifizierung von GFP-markierten Dot Verweilzeit Mit Fiji Software <ol><li> Installieren Fidschi (&quot;Fidschi ist nur ImageJ) Software 10 Verwendung der Autoren Anweisungen (http://fiji.sc/Fiji). </li><li> Führen Fiji und öffnen Sie die erworbenen mehrseitige TIFF-Datei mit Hilfe des Fidschi-Menü &quot;Datei-Öffnen&quot;. </li><li> Platzieren Sie eine Linie auf der Stelle von Interesse, mit der Fidschi-Werkzeugleiste Menü &quot;Straight Line Selection Tool&quot;. Optional können Sie die &quot;Segmented Linie Selection Tool&quot; oder &quot;Freihandlinie Selection Tool&quot;. In den hier vorgestellten Ergebnisse, wurde eine gerade Linie von 100 Pixeln (entsprechend 8,0 &amp; mgr; m) auf einer Tochterzelle (4A) platziert. </li><li> Einen kymograph Bildes im Menü Fiji &quot;Bild-Stacks-Dynamische Reslice </em&gt; &quot;(http://fiji.sc/Dynamic_Reslice) (4B). Optional &quot;Vertikal spiegeln&quot; und &quot;Um 90 Degrees&quot; in einem Kontrollkästchen Fenster sind ebenfalls verfügbar (nicht in den hier vorgestellten Ergebnisse verwendet). Die x- und y-Achse in der kymograph Bild zeigen die Linienposition (100 Pixeln entsprechend 8,0 &amp; mgr; m) und Beobachtungszeit (600 Pixel entsprechend 60 sec) bezeichnet. Wenn die kymograph Bild nicht zufriedenstellend ist, die Position und die Art (gerade, segmentiert und Freihand) der Linie auf mehrseitige Bild der geändert werden kann. Als die Linie ändert, ändert dynamisch die kymograph Bild. Speichern Sie eine kymograph Bild als TIFF-Datei über das Menü Fiji &quot;Datei-Speichern unter-Tiff&quot;. </li><li> Messen der Länge des Tropfens in der Ausrichtung der Zeitachse. <ol><li> Zur Geräuschreduzierung durchführen, tragen Sie eine Gauß-Filter auf die kymograph Bilder mit der Fidschi-Menü &quot;Process-Filter-Gaußschen Weichzeichner&quot;. Die &quot;Sigma (Radius) &quot;Parameter abstimmbar (1 Pixel Radius wird für die vorgestellten Ergebnisse verwendet). </li><li> Segment die Signalbereiche durch Schwellen, über das Menü Fiji &quot;Bild-Adjust-Threshold&quot;. HINWEIS: Es gibt mehrere Schwellen Algorithmen zur Auswahl. Dargestellt Ergebnissen wurde die &quot;Yen&quot; Algorithmus ausgewählt (4C). </li><li> Bereiten Sie, um die Zeit (y) messen -Achse Länge des Blobs über das Menü &quot;Analysieren-Set Messungen&quot;. Überprüfen Sie die &quot;Begrenzungsrechteck&quot; im Fenster &quot;Set Messungen&quot;. Im Idealfall sollte die Fläche so klein wie möglich sein, um Rauschen auszuschließen. Hier wurde die Mindestfläche auf 50 Pixel festgelegt. Messen Sie die Zeit (y) -Achse Länge des Blobs über das Menü &quot;Analysieren Analysieren-Particles&quot;. Um die Ergebniswerte zu erhalten und zu beweisen, Glaubwürdigkeit der Messbereiche, überprüfen Sie die &quot;Ergebnisse&quot; und &quot;In-Manager &lt;/ em&gt; &quot;Boxen. </li><li> Werte in der Spalte &quot;Größe&quot; gibt die Zeit (y) -Achse Längen für die gemessene Blob (4D). Speichern Sie die Werte mit der Ergebnistabelle Menü &quot;Datei-Speichern unter&quot; und berechnen und zu verarbeiten, die Datenmenge der Bild blob Dauern unter Verwendung eines statistischen Verpackung und / oder Tabellenkalkulationsprogramm (4E). </li></ol></li></ol>

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Der Autor hat nichts zu offenbaren.

In diesem Video-Artikel werden Protokolle zur Überwachung und Messung des dynamischen Verhaltens des GFP-PATROL1 Punkte auf der Stomata Komplex aus Arabidopsis thaliana angegeben. Wie hier gezeigt, ist vaem Beobachtung ein leistungsfähiges Werkzeug für Live-Imaging von Pflanzenzelloberflächen. Unter den für die GFP-PATROL1 Überwachungs hier verwendeten experimentellen Bedingungen gab es sehr wenig Fluoreszenzphotobleichen in der Probe für 1 Minute zur Videoaufzeichnung verwendet wird, weil die hochsensib...

The plant cell surface, including the plasma membrane and its immediately adjacent cytoplasm, is the main region of a plant cell&#8217;s perception and integration of biotic and abiotic cues from the extracellular environment. In response to these cues, cell surface components including plasma membrane proteins and the cortical cytoskeleton undergo dynamic changes, on a time scale of seconds to minutes1-4. Thus, real-time and high-resolution imaging of fluorescent proteins on the cell surface can illuminate a plant&#8217;s responses to environmental cues at the molecular level.
Confocal laser scanning microscopy is a powerful tool for determination of fluorescently-tagged protein localization3, however, it is often difficult to monitor the real-time protein dynamics because of its relatively long capturing times. An emerging technique for real-time monitoring of proteins in the plant cell is variable angle epifluorescence microscopy (VAEM), which is an adaptation of equipment usually used for total internal reflection fluorescence (TIRF) microscopy. In TIRF microscopy, the fluorescence-excitation light source is an evanescent light field that is generated when the entry angle of the laser is shallow enough to totally internally reflect light at the glass&#8211;water interface. The penetration depth of the evanescent light field is around 100 nm. TIRF microscopy is an outstanding tool for single molecule imaging, such as the detection of exocytosis in animal cells5. However, evanescent light cannot reach plasma membranes or the cortical cytoplasm in plant cells, because they have thick cell walls. Recently, TIRF microscopy equipment has been adapted by plant cell biologists, observing that a laser, if angled slightly more deeply than when being used to induce total internal reflection phenomena, could excite the surface of plant cell samples, resulting in high-quality plant cell imaging6,7. The excitation illumination depth is varied by adjusting the entry angle of the laser; therefore, this technique is described as VAEM. This optical system is also called variable angle TIRF microscopy (VA-TIRFM) because there is a possibility that total reflection may take place at the cell wall-periplasm interface7, however, the term VAEM is used in this article, as per the first report in plants6.
The goal of this protocol is to demonstrate practical procedures for using VAEM to visualize fluorescently-tagged protein dynamics on plant cell surfaces. Additionally, an image analysis protocol to quantify the residence time (duration of presence) of molecules is described for VAEM movie analysis. GFP-PATROL1 dot blinking on stomatal complex cells in Arabidopsis thaliana cotyledons is used as an example. PATROL1 was identified by forward genetic approaches as a causal gene of a stomatal response defect mutant in A. thaliana8. PATROL1 is a plant homolog of MUNC-13, which is a priming factor in synapse vesicle exocytosis8. In response to environmental cues, such as light or humidity, it is thought that PATROL1 reversibly regulates the delivery of a proton pump to plasma membranes in the stomatal complex. Stomatal complexes each comprise a pair of guard cells8 and subsidiary cells9, and they require a proton pump for stomatal movement. In these cells, GFP-tagged PATROL1 localizes to dot-like structures that remain on the plasma membrane for less than 1 min9.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Inverted microscope</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">IX-73</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TIRF unit</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">IX3-RFAEVAW</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">TIRF objective lens&#160;</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">UAPON 100 &#215; OTIRF&#160;</td>
			<td>NA = 1.49</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Laser angle control box</td>
			<td style="width:71px;">Chuo Seiki</td>
			<td style="width:119px;">QT-AK</td>
			<td></td>
		</tr>
		<tr height="64">
			<td height="64" style="height:64px;width:216px;">Optically pumped semiconductor laser</td>
			<td style="width:71px;">Coherent</td>
			<td style="width:119px;">SapphireTM LP USB 488-20 CDRH Laser</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">510&#8211;550 nm band-pass filter</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">U-FBNA</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">EM CCD camera</td>
			<td style="width:71px;">Hamamatsu Photonics</td>
			<td style="width:119px;">ImagEM C9100-13</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">C-mount camera magnification change unit&#160;</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">U-TVCAC</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">MetaMorph software</td>
			<td style="width:71px;">Molecular Devices</td>
			<td style="width:119px;">MetaMorph version 7.7.11.0</td>
			<td></td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">TIRF microscopy manual</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">AX7385</td>
			<td style="width:167px;">Instructions: Total Internal Reflection Illumination System (Printed in Japan on August 24, 2012)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Immersion oil</td>
			<td style="width:71px;">Olympus</td>
			<td style="width:119px;">Immersion Oil Typr-F</td>
			<td>ne = 1.518 (23 degrees)</td>
		</tr>
	</tbody>
</table>

real-time imaging of plant cell surface dynamics with variable-angle epifluorescence microscopy

A plant&#8217;s cell surface is its interface for perceiving environmental cues; it responds with cell biological changes such as membrane trafficking and cytoskeletal rearrangement. Real-time and high-resolution image analysis of such intracellular events will increase the understanding of plant cell biology at the molecular level. Variable angle epifluorescence microscopy (VAEM) is an emerging technique that provides high-quality, time-lapse images of fluorescently-labeled proteins on the plant cell surface. In this article, practical procedures are described for VAEM specimen preparation, adjustment of the VAEM optical system, movie capturing and image analysis. As an example of VAEM observation, representative results are presented on the dynamics of PATROL1. This is a protein essential for stomatal movement, thought to be involved in proton pump delivery to plasma membranes in the stomatal complex of Arabidopsis thaliana. VAEM real-time observation of guard cells and subsidiary cells in A. thaliana cotyledons showed that fluorescently-tagged PATROL1 appeared as dot-like structures on plasma membranes for several seconds and then disappeared. Kymograph analysis of VAEM movie data determined the time distribution of the presence (termed &#8216;residence time&#8217;) of the dot-like structures. The use of VAEM is discussed in the context of this example.

In diesem Video-Artikel, der Protokolle für vaem Beobachtung der GFP-PATROL1 in A. thaliana cotyledon Stomata komplexen Zellen werden zur Verfügung gestellt. Sky Drop Montage ist ein einfaches Herstellungsverfahren, die dazu beitragen, das Auftreten von Luftblasen in vaem Zubereitungen von A. kann thaliana Cotyledonen (Abbildung 1). Hoher Neigungswinkel der Eintritts Laser und / oder z-Positionierung von Proben für vaem liefert ein unklares Bild. Wenn das geschieht, ist es ...

Watch this Scientific Journal Video about Real-time Imaging of Plant Cell Surface Dynamics with Variable-angle Epifluorescence Microscopy at JoVE.com

Real-time Imaging of Plant Cell Surface Dynamics with Variable-angle Epifluorescence Microscopy

Das Ziel des Protokolls ist es, zu demonstrieren, wie fluoreszenzmarkierte Proteindynamik zu Pflanzenzelloberflächen mit variablem Winkel Epifluoreszenzmikroskopie, die blinkende Punkte von GFP-markiertem PATROL1 ein Membrantransportprotein zu überwachen, in der Zelle Kortex der Stomata Komplex in Arabidopsis thaliana.

Echtzeit-Imaging von Plant Cell Oberflächen Dynamics mit variabler Winkel Epifluoreszenzmikroskopie

A plant&#8217;s cell surface is its interface for perceiving environmental cues; it responds with cell biological changes such as membrane trafficking and ...

real-time-imaging-plant-cell-surface-dynamics-with-variable-angle

Research

JoVE Journal

Biology

8.9K Aufrufe.  The University of Tokyo.  Das Ziel des Protokolls ist es, zu demonstrieren, wie fluoreszenzmarkierte Proteindynamik zu Pflanzenzelloberflächen mit variablem Winkel Epifluoreszenzmikroskopie, die blinkende Punkte von GFP-markiertem PATROL1 ein Membrantransportprotein zu überwachen, in der Zelle Kortex der Stomata Komplex in Arabidopsis thaliana. 

Serie: Real-time Imaging of Plant Cell Surface Dynamics with Variable-angle Epifluorescence Microscopy

Live Cell Imaging of F-actin Dynamics via Fluorescent Speckle Microscopy (FSM)

In this protocol we describe the use of Fluorescent Speckle Microscopy (FSM) to capture high-resolution images of actin dynamics in PtK1 cells. A unique advantage of FSM is its ability to capture the movement and turnover kinetics (assembly/disassembly) of the F-actin network within living cells. This technique is particularly useful in deriving quantitative measurements of F-actin dynamics when paired with computer vision software (qFSM).  We describe  the selection, microinjection and visualization of fluorescent actin probes in living cells. Importantly, similar procedures are applicable to visualizing other macomolecular assemblies. FSM has been demonstrated for microtubules, intermediate filaments, and adhesion complexes.  

Live Cell Imaging of F-actin Dynamics via Fluorescent Speckle Microscopy FSM

Selection, microinjection, and imaging of fluorescently-labeled F-actin via fluorescent speckle microscopy (FSM).

Live Cell Imaging von F-Aktin Dynamics über Fluorescent Speckle Microscopy (FSM)

In this protocol we describe the use of Fluorescent Speckle Microscopy (FSM) to capture high-resolution images of actin dynamics in PtK1 cells. A unique ...

Forschung

Biologie

Assembly, Loading, and Alignment of an Analytical Ultracentrifuge Sample Cell

The analytical ultracentrifuge (AUC) is a powerful biophysical tool that allows us to record macromolecular sedimentation profiles during high speed centrifugation. When properly planned and executed, an AUC sedimentation velocity or sedimentation equilibrium experiment can reveal a great deal about a protein in regards to size and shape, sample purity, sedimentation coefficient, oligomerization states and protein-protein interactions.
This technique, however, requires a rigorous level of technical attention. Sample cells hold a sectored center piece sandwiched between two window assemblies. They are sealed with a torque pressure of around 120-140 in/lbs. Reference buffer and sample are loaded into the centerpiece sectors and then after sealing, the cells are precisely aligned into a titanium rotor so that the optical detection systems scan both sample and reference buffer in the same radial path midline through each centerpiece sector while rotating at speeds of up to 60, 000 rpm and under very high vacuum
Not only is proper sample cell assembly critical, sample cell components are very expensive and must be properly cared for to ensure they are in optimum working condition in order to avoid leaks and breakage during experiments. Handle windows carefully, for even the slightest crack or scratch can lead to breakage in the centrifuge. The contact between centerpiece and windows must be as tight as possible; i.e. no Newton s rings should be visible after torque pressure is applied. Dust, lint, scratches and oils on either the windows or the centerpiece all compromise this contact and can very easily lead to leaking of solutions from one sector to another or leaking out of the centerpiece all together. Not only are precious samples lost, leaking of solutions during an experiment will cause an imbalance of pressure in the cell that often leads to broken windows and centerpieces. In addition, plug gaskets and housing plugs must be securely in place to avoid solutions being pulled out of the centerpiece sector through the loading holes by the high vacuum in the centrifuge chamber. Window liners and gaskets must be free of breaks and cracks that could cause movement resulting in broken windows.
This video will demonstrate our procedures of sample cell assembly, torque, loading and rotor alignment to help minimize component damage, solution leaking and breakage during the perfect AUC experiment.

The analytical ultracentrifuge (AUC) sample cell holds sample and reference buffer and during experiments and is exposed to high vacuum and rotor speeds up to 60,000 rpm. This video will demonstrate the rigorous attention to detail necessary for assembly, loading and alignment of this very important component of an AUC experiment.

Montage-, Lade-und Alignment einer analytischen Ultrazentrifuge Messkammerdirektanschluss

The analytical ultracentrifuge (AUC) is a powerful biophysical tool that allows us to record macromolecular sedimentation profiles during high speed ...

Cell Electrofusion Visualized with Fluorescence Microscopy

Cell electrofusion is a safe, non-viral and non-chemical method that can be used for preparing hybrid cells for human therapy. Electrofusion involves application of short high-voltage electric pulses to cells that are in close contact. Application of short, high-voltage electric pulses causes destabilization of cell plasma membranes. Destabilized membranes are more permeable for different molecules and also prone to fusion with any neighboring destabilized membranes. Electrofusion is thus a convenient method to achieve a non-specific fusion of very different cells in vitro. In order to obtain fusion, cell membranes, destabilized by electric field, must be in a close contact to allow merging of their lipid bilayers and consequently their cytoplasm. In this video, we demonstrate efficient electrofusion of cells in vitro by means of modified adherence method. In this method, cells are allowed to attach only slightly to the surface of the well, so that medium can be exchanged and cells still preserve their spherical shape. Fusion visualization is assessed by pre-labeling of the cytoplasm of cells with different fluorescent cell tracker dyes; half of the cells are labeled with orange CMRA and the other half with green CMFDA. Fusion yield is determined as the number of dually fluorescent cells divided with the number of all cells multiplied by two.

In this video we demonstrate efficient electrofusion of cells in vitro by means of modified adherence method using electroporation and the subsequent detection of fused cells visualization with fluorescence microscopy.

Zell Elektroschweißmuffe Visualisierte mit Fluoreszenz-Mikroskopie

Cell electrofusion is a safe, non-viral and non-chemical method that can be used for preparing hybrid cells for human therapy. Electrofusion involves ...

Avidity-based Extracellular Interaction Screening (AVEXIS) for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ensuring cohesion within multicellular organisms. Proteins predicted to form extracellular interactions are encoded by approximately a quarter of human genes1, but despite their importance and abundance, the majority of these proteins have no documented binding partner. Primarily, this is due to their biochemical intractability: membrane-embedded proteins are difficult to solubilise in their native conformation and contain structurally-important posttranslational modifications. Also, the interaction affinities between receptor proteins are often characterised by extremely low interaction strengths (half-lives &lt; 1 second) precluding their detection with many commonly-used high throughput methods2. 
Here, we describe an assay, AVEXIS (AVidity-based EXtracellular Interaction Screen) that overcomes these technical challenges enabling the detection of very weak protein interactions (t1/2 &le; 0.1 sec) with a low false positive rate3. The assay is usually implemented in a high throughput format to enable the systematic screening of many thousands of interactions in a convenient microtitre plate format (Fig. 1). It relies on the production of soluble recombinant protein libraries that contain the ectodomain fragments of cell surface receptors or secreted proteins within which to screen for interactions; therefore, this approach is suitable for type I, type II, GPI-linked cell surface receptors and secreted proteins but not for multipass membrane proteins such as ion channels or transporters.
The recombinant protein libraries are produced using a convenient and high-level mammalian expression system4, to ensure that important posttranslational modifications such as glycosylation and disulphide bonds are added. Expressed recombinant proteins are secreted into the medium and produced in two forms: a biotinylated bait which can be captured on a streptavidin-coated solid phase suitable for screening, and a pentamerised enzyme-tagged (&beta;-lactamase) prey. The bait and prey proteins are presented to each other in a binary fashion to detect direct interactions between them, similar to a conventional ELISA (Fig. 1). The pentamerisation of the proteins in the prey is achieved through a peptide sequence from the cartilage oligomeric matrix protein (COMP) and increases the local concentration of the ectodomains thereby providing significant avidity gains to enable even very transient interactions to be detected. By normalising the activities of both the bait and prey to predetermined levels prior to screening, we have shown that interactions having monomeric half-lives of 0.1 sec can be detected with low false positive rates3.

Avidity-based Extracellular Interaction Screening AVEXIS for the Scalable Detection of Low-affinity Extracellular Receptor-Ligand Interactions

AVEXIS is a high throughput protein interaction assay developed to systematically screen for novel extracellular receptor-ligand pairs involved in cellular recognition processes. It is specifically designed to detect transient protein interactions that are difficult to identify using other high throughput approaches.

Avidität-basierte extrazelluläre Wechselwirkung Screening (AVEXIS) für die Erkennung von Scalable Low-Affinität extrazellulären Rezeptor-Ligand-Wechselwirkungen

Extracellular protein:protein interactions between secreted or membrane-tethered proteins are critical for both initiating intercellular communication and ...

Tandem High-pressure Freezing and Quick Freeze Substitution of Plant Tissues for Transmission Electron Microscopy

Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, because of laborious and time-consuming protocols that also demand experience in preparation of artifact-free samples, TEM is not considered a user-friendly technique. Traditional sample preparation for TEM used chemical fixatives to preserve cellular structures. High-pressure freezing is the cryofixation of biological samples under high pressures to produce very fast cooling rates, thereby restricting ice formation, which is detrimental to the integrity of cellular ultrastructure. High-pressure freezing and freeze substitution are currently the methods of choice for producing the highest quality morphology in resin sections for TEM. These methods minimize the artifacts normally associated with conventional processing for TEM of thin sections. After cryofixation the frozen water in the sample is replaced with liquid organic solvent at low temperatures, a process called freeze substitution. Freeze substitution is typically carried out over several days in dedicated, costly equipment. A recent innovation allows the process to be completed in three hours, instead of the usual two days. This is typically followed by several more days of sample preparation that includes infiltration and embedding in epoxy resins before sectioning. Here we present a protocol combining high-pressure freezing and quick freeze substitution that enables plant sample fixation to be accomplished within hours. The protocol can readily be adapted for working with other tissues or organisms. Plant tissues are of special concern because of the presence of aerated spaces and water-filled vacuoles that impede ice-free freezing of water. In addition, the process of chemical fixation is especially long in plants due to cell walls impeding the penetration of the chemicals to deep within the tissues. Plant tissues are therefore particularly challenging, but this protocol is reliable and produces samples of the highest quality.

Obtaining high-quality transmission electron microscopy images is challenging, especially in the case of plant cells, which have abundant large water-filled vacuoles and aerated spaces. Tandem high-pressure freezing and quick freeze substitution greatly reduce preparation time of plant samples for TEM while producing samples with excellent ultrastructural preservation.

Tandem-Hochdruck-Schnell Einfrieren und Gefriersubstitution von Pflanzengeweben für die Transmissionselektronenmikroskopie

Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, ...

Real Time Measurements of Membrane Protein:Receptor Interactions Using Surface Plasmon Resonance (SPR)

Protein-protein interactions are pivotal to most, if not all, physiological processes, and understanding the nature of such interactions is a central step in biological research. Surface Plasmon Resonance (SPR) is a sensitive detection technique for label-free study of bio-molecular interactions in real time. In a typical SPR experiment, one component (usually a protein, termed 'ligand') is immobilized onto a sensor chip surface, while the other (the 'analyte') is free in solution and is injected over the surface. Association and dissociation of the analyte from the ligand are measured and plotted in real time on a graph called a sensogram, from which pre-equilibrium and equilibrium data is derived. Being label-free, consuming low amounts of material, and providing pre-equilibrium kinetic data, often makes SPR the method of choice when studying dynamics of protein interactions. However, one has to keep in mind that due to the method's high sensitivity, the data obtained needs to be carefully analyzed, and supported by other biochemical methods. 
SPR is particularly suitable for studying membrane proteins since it consumes small amounts of purified material, and is compatible with lipids and detergents. This protocol describes an SPR experiment characterizing the kinetic properties of the interaction between a membrane protein (an ABC transporter) and a soluble protein (the transporter's cognate substrate binding protein).

Real Time Measurements of Membrane Protein:Receptor Interactions Using Surface Plasmon Resonance SPR

Surface Plasmon Resonance (SPR) is a label-free method for detecting bio-molecular interactions in real time. Herein, a protocol for a membrane protein:receptor interaction experiment is described, while discussing the pros and cons of the technique.

Echtzeit-Messungen von Membranprotein: Rezeptor-Wechselwirkungen Mit Oberflächenplasmonenresonanz (SPR)

Protein-protein interactions are pivotal to most, if not all, physiological processes, and  understanding the nature of such interactions is a central ...

Real Time Analysis of Metabolic Profile in Ex Vivo Mouse Intestinal Crypt Organoid Cultures

The small intestinal mucosa exhibits a repetitive architecture organized into two fundamental structures: villi, projecting into the intestinal lumen and composed of mature enterocytes, goblet cells and enteroendocrine cells; and crypts, residing proximal to the submucosa and the muscularis, harboring adult stem and progenitor cells and mature Paneth cells, as well as stromal and immune cells of the crypt microenvironment. Until the last few years, in vitro studies of small intestine was limited to cell lines derived from either benign or malignant tumors, and did not represent the physiology of normal intestinal epithelia and the influence of the microenvironment in which they reside. Here, we demonstrate a method adapted from Sato et al. (2009) for culturing primary mouse intestinal crypt organoids derived from C57BL/6 mice. In addition, we present the use of crypt organoid cultures to assay the crypt metabolic profile in real time by measurement of basal oxygen consumption, glycolytic rate, ATP production and respiratory capacity. Organoids maintain properties defined by their source and retain aspects of their metabolic adaptation reflected by oxygen consumption and extracellular acidification rates. Real time metabolic studies in this crypt organoid culture system are a powerful tool to study crypt organoid energy metabolism, and how it can be modulated by nutritional and pharmacological factors.

Real Time Analysis of Metabolic Profile in Ex Vivo Mouse Intestinal Crypt Organoid Cultures

Small intestinal crypt organoids cultured ex vivo provide a tissue culture system that recapitulates growth of crypts dependent on stem cells and their niche. We established a method to assay the metabolic profile in real time in primary mouse crypt organoids. We found organoids maintain physiological properties defined by their source.

Echtzeit-Analyse von Stoffwechselprofil in<em&gt; Ex Vivo</em&gt; Maus Intestinale Crypt Organoide Kulturen

The small intestinal mucosa exhibits a repetitive architecture organized into two fundamental structures: villi, projecting into the intestinal lumen and ...

Visualizing Stromule Frequency with Fluorescence Microscopy

Stromules, or "stroma-filled tubules", are narrow, tubular extensions from the surface of the chloroplast that are universally observed in plant cells but whose functions remain mysterious. Alongside growing attention on the role of chloroplasts in coordinating plant responses to stress, interest in stromules and their relationship to chloroplast signaling dynamics has increased in recent years, aided by advances in fluorescence microscopy and protein fluorophores that allow for rapid, accurate visualization of stromule dynamics. Here, we provide detailed protocols to assay stromule frequency in the epidermal chloroplasts of Nicotiana benthamiana, an excellent model system for investigating chloroplast stromule biology. We also provide methods for visualizing chloroplast stromules in vitro by extracting chloroplasts from leaves. Finally, we outline sampling strategies and statistical approaches to analyze differences in stromule frequencies in response to stimuli, such as environmental stress, chemical treatments, or gene silencing. Researchers can use these protocols as a starting point to develop new methods for innovative experiments to explore how and why chloroplasts make stromules.

Protocols to investigate the dynamics of chloroplast stromules, the stroma-filled tubules that extend from the surface of chloroplasts, are described.

Visualizing Stromulus Frequenz mit Fluoreszenzmikroskopie

Stromules, or "stroma-filled tubules", are narrow, tubular extensions from the surface of the chloroplast that are universally observed in plant cells but ...

Light Sheet Fluorescence Microscopy of Plant Roots Growing on the Surface of a Gel

One of the key questions in understanding plant development is how single cells behave in a larger context of the tissue. Therefore, it requires the observation of the whole organ with a high spatial- as well as temporal resolution over prolonged periods of time, which may cause photo-toxic effects. This protocol shows a plant sample preparation method for light-sheet microscopy, which is characterized by mounting the plant vertically on the surface of a gel. The plant is mounted in such a way that the roots are submerged in a liquid medium while the leaves remain in the air. In order to ensure photosynthetic activity of the plant, a custom-made lighting system illuminates the leaves. To keep the roots in darkness the water surface is covered with sheets of black plastic foil. This method allows long-term imaging of plant organ development in standardized conditions.

This protocol shows a plant sample preparation method for light-sheet microscopy. The setup is characterized by mounting the plant vertically on the surface of a gel and letting it grow in controlled bright conditions. This allows long-term observation of plant organ development in standardized conditions.

Lichtblatt Fluoreszenzmikroskopie von Pflanzenwurzeln wachsen auf der Oberfläche eines Gel

One of the key questions in understanding plant development is how single cells behave in a larger context of the tissue. Therefore, it requires the ...

Flash-and-Freeze: A Novel Technique to Capture Membrane Dynamics with Electron Microscopy

Cells constantly change their membrane architecture and protein distribution, but it is extremely difficult to visualize these events at a temporal and spatial resolution on the order of ms and nm, respectively. We have developed a time-resolved electron microscopy technique, &#34;flash-and-freeze,&#34; that induces cellular events with optogenetics and visualizes the resulting membrane dynamics by freezing cells at defined time points after stimulation. To demonstrate this technique, we expressed channelrhodopsin, a light-sensitive cation channel, in mouse hippocampal neurons. A flash of light stimulates neuronal activity and induces neurotransmitter release from synaptic terminals through the fusion of synaptic vesicles. The optogenetic stimulation of neurons is coupled with high-pressure freezing to follow morphological changes during synaptic transmission. Using a commercial instrument, we captured the fusion of synaptic vesicles and the recovery of the synaptic vesicle membrane. To visualize the sequence of events, large datasets were generated and analyzed blindly, since morphological changes were followed in different cells over time. Nevertheless, flash-and-freeze allows the visualization of membrane dynamics in electron micrographs with ms temporal resolution.

We developed a novel technique in electron microscopy, &#34;flash-and-freeze,&#34; that enables the visualization of membrane dynamics with ms temporal resolution. This technique combines the optogenetic stimulation of neurons with high-pressure freezing. Here, we demonstrate the procedures and describe the protocols in detail.

Flash-and-Freeze-: eine neuartige Technik Membrandynamik mit Elektronenmikroskopie zu erfassen

Cells constantly change their membrane architecture and protein distribution, but it is extremely difficult to visualize these events at a temporal and ...