Diese Arbeit wurde vom NIH Grant EY 14990 unterstützt.

Teil 1: Dissection und Bipolar Zellisolation <ol><li> Bereiten Sie Lösungen in Tabelle 2 aufgeführt; Der pH-Wert von Beringer &quot;(extern)-Lösungen sollten mit NaOH auf 7,4 eingestellt und der pH-Wert der internen Lösung sollte auf 7,2 mit CsOH eingestellt werden. Schützen interne Lösung vor Licht mit Alufolie und halten Sie sie bei 4 ° C bis zur Verwendung; </li><li> Dark-Anpassung einen Goldfisch für mindestens 30 Minuten vor der Dissektion; </li><li> Während das Tier dunkel passt, bereiten 5 mL der Hyaluronidase (Typ V Hyaluronidase, 1100 Einheiten / ml in niedrigen Ca 2 + Ringer; Sigma, St. Louis, MO) und 10 ml der L-Cystein (0,5 mg / mL in niedrigen Ca 2 + Ringer-) Lösungen und wiegen das Papain (gefriergetrocknetes Pulver, 40 Einheiten / ml, Sigma, St. Louis, MO) für 5 ml der Verdauung Lösung; </li><li> Euthanize die Goldfische durch schnelle Enthauptung mit chirurgischer Schere und zerstören das Gehirn und das Rückenmark mit einem # 11 Skalpell; </li><li> Entfernen Sie die Augen durch die Zerstörung der extra-Augenmuskeln mit Hilfe eines # 7 gebogenen Pinzette Dumont und Schneiden des Sehnervs mit Iris Schere; </li><li> Legen Sie ein Auge Glühbirne auf einem Stück Filterpapier und Punktion der Sclerallimbus mit der Spitze eines Nr. 11 Skalpell; </li><li> Führen Sie die Klinge aus einem Paar von Vannas Schere innerhalb der punktierten ganzen und schneiden Sie die ganze vordere Segment entfernt; </li><li> Legen Sie ein kleines Stück Filterpapier auf der Oberseite des restlichen Augenbecher und üben einen gewissen Druck, um das Papier mit Glaskörper einweichen; </li><li> Heben Sie das Filterpapier mit der Netzhaut verbunden ist und schneiden Sie den Sehnerv mit einem Nennwert von Vannas Schere; </li><li> Legen Sie das Filterpapier mit der Netzhaut in einem 35 mm Kunststoff-Kulturschale mit Hyaluronidase-Lösung und Abziehen der Netzhaut vom Filterpapier mit Hilfe von # 7 Dumont Pinzetten; </li><li> Cut der Netzhaut in 4-6 Stücke mit der Hälfte der industriellen Stahl einseitig geschliffene Klinge und ließ es in die Hyaluronidase-Lösung für 20 Minuten zu sitzen; </li><li> Während des Wartens auf Hyaluronidase in Kraft treten, 5 ml der L-Cystein-Lösung, die Papain und lassen Sie es sich, bis die Flüssigkeit transparent (ca. 5-10 Minuten); </li><li> Waschen Sie die Teile der Netzhaut 3x in niedrigen Ca 2 + Ringer und ließ sie in der Papain-Lösung setzen sie für 30-35 Minuten; </li><li> Waschen Sie die Teile der Netzhaut 3x in niedrigen Ca 2 + Ringer und lagern Sie sie bis zur Verwendung bei 4 ° C in einer 35 mm Kunststoff-Kulturschale mit niedrigem Ca 2 + Ringer; </li><li> Um distanzieren die Zellen, legen Sie ein Stück der Netzhaut in einem Mikrozentrifugenröhrchen mit 500 ml niedrige Ca 2 + Ringer und langsam verreiben der Netzhaut durch Pipettieren es rauf und runter mit einem Glas Dissoziation Pipette vorsichtig, keine Luftblasen zu produzieren. Dissoziation Pipetten werden durch Aufheizen der Spitze einer Glas-Pasteurpipette mit einem Bunsenbrenner und leicht verbiegen mit Hilfe der anatomischen Pinzette hergestellt; </li><li> Platte die isolierten Zellen durch Zugabe von einem Tropfen des retinalen Suspension auf eine hausgemachte Aufnahme Kammer zuvor mit 2 ml niedrige Ca 2 + Ringer gefüllt. Die Kammer besteht aus der unteren Hälfte eines 35-mm-Kunststoff-Kulturschale mit einem kreisrunden Loch in der Mitte und einem runden Deckglas von 1,78 Brechungsindex Glas (PlanOptik, Deutschland) geklebt, um den Boden mit einem Silizium-Elastomer (Sylgard 184; Dow Corning , Midland, MI). </li></ol> Teil 2: Bipolarzelle Be-und Wash Out TIRF Bildgebung von synaptischen Vesikeln erfolgt am besten mit Hilfe einer objektiven Typ TIRFM Mikroskop mit einer sehr hohen NA objektive und einer empfindlichen Kamera durchgeführt. Für unsere Experimente, wählen wir ein 1,65 NA Objektiv (Apo x100 O HR, NA 1,65, Olympus, Japan) mit einem EMCCD (Cascade 512B, Roper Scientific, Tucson, AZ) zu verwenden. Die Verwendung der sehr hohen NA Ziel erfordert den Einsatz von hohem Brechungsindex Deckgläser und Immersionsflüssigkeit (di-Iodmethan mit Schwefel). Unter unseren Bedingungen ist Anregungslicht zu einer exponentiell abklingenden Feld mit einer Länge konstant von ca. 50 nm beschränkt. <ol><li> Fügen Sie einen Tropfen Flüssigkeit mit hohem Brechungsindex (M-Serie, Brechungsindex = 1,7800, Cargille Labs, Cedar Grove, NJ), die Mikroskop-Objektiv; </li><li> Legen Sie die Aufnahme Kammer vorsichtig auf der Oberseite des Mikroskop-Objektivs und vorsichtig montieren Masseelektrode und Superfusion Ausfahrt Rohr Kammer; </li><li> Lassen Kammer Mikroskop sitzen für 10-20 Minuten, damit Zellen zu sinken und sich an der Unterseite; </li><li> In der Zwischenzeit bereiten 5 ml einer 1 mM Trolox ® ((±)- 6-Hydroxy-2 ,5,7,8-tetramethylchromane-2-carbonsäure; Sigma, St. Louis, MO)-Lösung in hoher K + Ringer- . Beschallen, bis es gelöst; </li><li> Bereiten Sie 15 ml ADVASEP-7 Waschlösung: 1 mM ADVASEP-7 (Sigma, St. Louis, MO) in niedrigen Ca 2 + Ringer. Beachten Sie, dass ADVASEP-7 Verwendung optional ist und kann bei Bedarf unterdrückt werden; </li><li> Spülen Sie die Superfusion lines und fügen ADVASEP-7 Waschlösung, niedrige Ca 2 + Ringer und Ringer-Kontrolle der Superfusion System; </li><li> Pull loading Pipetten aus dünnwandigen Borosilikatglas (Kwik-Fil ® TW150-3; WPI, Sarasota, FL). Puffer Pipette Widerstände sind in den 1,5-2,5 MOhm-Bereich; </li><li> Bereiten Sie den FM1-43 ® (N-(3-triethylammoniumpropyl) -4 - (4 - (dibutylamino) Styryl) pyridinium Dibromid &quot;, eine spezielle Verpackung&quot;; Invitrogen, Carlsbad, CA)-Lösungen. Stellen Sie zunächst eine 1 mM Lager von zusätzlich 160 ul destilliertem Wasser auf ein Fläschchen (100 mg) des FM1-43 ®. Diese Aktie kann bei 4 ° C aufbewahrt werden bis zu einer Woche. Anschließend 5 ul des FM1-43 ® bis 1 mL hohen K + Ringer + 1mM Trolox ®. Protect-Lösung von Licht mit Aluminiumfolie und halten Sie sie bei 4 ° C bis zur Verwendung; </li><li> Schalten Sie das Mikroskop Hellfeld Licht auf und die Suche nach intakter bipolaren Zellen. Leicht tippen Sie auf das Mikroskop, um sicherzustellen, dass die Neuronen fest an den Boden der Kammer angebracht ist; </li><li> Positionieren Sie die Superfusion Stift in der Nähe der Zelle von Interesse und kontinuierlich versorgen die Vorbereitung mit niedrigen Ca 2 + Ringer; </li><li> Schalten Sie die Raumbeleuchtung und fügen Sie einen roten langen Pass Filter (dh RG630, Schott, Deutschland), um den optischen Pfad zur Anregung des FM Farbstoff zu minimieren; </li><li> Füllen Sie einen Laden Pipette mit 10 ul der FM Farbstofflösung, montieren Sie die Pipette in den Mikromanipulator und senken Sie die Pipette auf die Vorbereitung ohne Überdruck, bis sie an der gleichen Bildebene als die bipolare Zelle, die Sie laden möchten, ist. Vergewissern Sie sich, mindestens zwei Elektrodenhalter: die eine für den FM-Farbstoff kann nicht für Patch-Clamp verwendet werden, oder es kann die intrazelluläre Lösung verunreinigen; </li><li> Position der Puffer Öffnung in einem Abstand von etwa 10 pm aus der Axonterminal, drehen Sie die Superfusion System aus und puff der Farbstoff-Lösung für 10 Sekunden durch Drehen der Pipette Überdruck auf; </li><li> Drehen Sie den Überdruck ab und, ohne Bewegung der Pipette, 30 Sekunden warten; </li><li> Schalten Sie die Superfusion auf und tauchen den Raum in ADVASEP-7-Lösung für 5 Minuten. In der Zwischenzeit, entfernen Sie den Puffer Pipette aus dem Bad; </li><li> Nach 5 Minuten zu niedrigen Ca 2 + Ringer-Schalter und versorgen die Kammer für 25-30 Minuten, um das Entfernen von überschüssigem Farbstoff zu ermöglichen. </li></ol> Teil 3: Patch-Clamp-und TIRFM Imaging <ol><li> Während der Vorbereitung ist das Auswaschen, ziehen Patch-Pipetten aus dickwandigem Borosilikatglas (B150-86 bis 10; Sutter Instrument Company, Novato, CA). Patch-Pipette Widerstände sind in der 8-10 MOhm-Bereich; </li><li> Nach Auswaschen beendet ist, legen Sie das Axon-Terminal in der Mitte des Sichtfeldes; </li><li> Füllen Sie ein Patch-Pipette mit 7μL der internen Lösung, tippen Sie auf die Pipette, um loszuwerden, Luftblasen, Mantel der Pipette mit geschmolzenem Dentalwachs (Sticky Wax; Kerr Corporation, Orange, CA) und montieren Sie ihn in den Mikromanipulator; </li><li> Schalten Sie die Pipette Überdruck auf und senken Sie die Pipette langsam auf die Vorbereitung. Überprüfen Pipette Widerstand in den Verstärker und richtige Pipette Offsets und Kapazität mit dem jeweiligen Verstärker steuert; </li><li> Schalten Sie die Superfusion auf Ringer-Kontrolle. So erstellen Sie eine Gigaseal zwischen der Pipette und der Zelle, leicht berühren die Spitze der Elektrode gegen die Zellkörper und drehen Sie die Pipette Überdruck ab, während sanft Anlegen von Unterdruck an der Elektrode; </li><li> Während versiegelt, wählen Sie &quot;ganze Zelle&quot;-Modus in den Verstärker und setzen Sie die Zelle Haltepotential bis -60 mV; </li><li> Wählen Sie eine Region von Interesse, mit der Imaging-Software, die die ganze Axonterminal umfasst, schalten Sie das Hellfeld Licht aus und durch kurzes Aussetzen (30 ms) das Terminal mit dem 488 nm Laser, finden Sie den richtigen Brennebene für TIRF Bildgebung; </li><li> Pause in die Zelle, indem Sie die &quot;zappen&quot;-Befehl des Verstärkers während der Anwendung leicht negativen Druck auf die Pipette; </li><li> Richtig für die Zell-Kapazität und Vorwiderstand, und wenden Sie dann die Spannung Protokoll von Interesse, während die Abbildung der Bewegung von synaptischen Vesikeln. Es ist in dieser Phase wichtig, dass die Spannung Protokoll, um die Bildrate synchronisiert. In unserem Fall, jedes Bild 30 ms lang ist, so dass die Spannung Veränderungen in Vielfachen dieses Wertes (dh alle 300 ms oder 10 Frames); </li><li> Warten Sie mindestens 40 Sekunden zwischen den Prüfungen für die Wiederherstellung zu ermöglichen; </li><li> So überprüfen Sie die Position der synaptischen Bänder, fotografieren, während Sie den 561 nm Laser auf. </li></ol><img src="/files/ftp_upload/1305/fig1.jpg" alt="Abbildung 1" /> Abbildung 1: Der Versuchsaufbau. A 488 nm-Laser (blau) wird an die Peripherie der hinteren Brennebene des Objektivs ausgerichtet und leidet unter Totalreflexion, wenn es das Glas-wässrigen Medium-Schnittstelle erreicht. Das elektromagnetische Feld des reflektierten Strahls erzeugt regt das Fluorophor in den synaptischen Vesikeln am nächsten an der bott geladenom des Glases Kammer, die dann fluoreszieren (grün). Das Fluoreszenzlicht wird dann auf das Auge des Beobachters (siehe Bild) oder zu einer CCD-Kamera geleitet. Das Membranpotential der abgebildeten Zellen gleichzeitig von Patch-Clamp ihnen kontrolliert. Dieser Ansatz ermöglicht die Untersuchung der Beziehung zwischen eingehenden Signale (die Membran-Spannung) und der neuronalen Ausgang (Exozytose). <img src="/files/ftp_upload/1305/fig2.jpg" alt="Abbildung 2" /> Abbildung 2: Typische Ergebnisse. Links: Hellfeldbild eines isolierten Goldfisch bipolaren Zellen. Oben rechts: TIRF Bild von den synaptischen Vesikeln in der bipolaren Zellen Axonterminal mit FM 1-43 geladen ® und abgebildet mit der 488 nm-Laser (FM Farbstoff). Unten rechts: Bild der gleichen Klemme nach dem Patchen der Zelle und die Abbildung der Axon-Terminal mit dem 561 nm-Laser. Synaptic Bänder werden durch die Rhodamin-basierte RIBEYE-bindende Peptid (Rpep_rhod) gekennzeichnet. Tabelle 1: Spezifische Reagenzien und Geräte. <table border="1" cellspacing="0" cellpadding="0"><tbody><tr><td> Name </td><td> Typ </td><td> Hersteller </td><td> Katalog </td><td> Kommentar </td></tr><tr><td> - </td><td> Air Table </td><td> Newport Corporation </td><td> - </td><td> - </td></tr><tr><td> IX70 </td><td> Inverses Mikroskop </td><td> Olymp </td><td> - </td><td> Ausgestattet mit einer Wolfram-Lampe für Hellfeld und eine seitliche Öffnung Port für TIRF </td></tr><tr><td> TH4-100 </td><td> Lamp Power Source </td><td> Olymp </td><td> - </td><td> - </td></tr><tr><td> FF498_581-DI01 </td><td> Dichroitische Filter </td><td> Semrock </td><td> - </td><td> - </td></tr><tr><td> NF01-405_488_568 </td><td> Emission Filter </td><td> Semrock </td><td> - </td><td> - </td></tr><tr><td> Apo x100 O HR </td><td> Ziel </td><td> Olymp </td><td> - </td><td> NA 1,65 </td></tr><tr><td> RG630 </td><td> Red Glass Filter </td><td> Schott </td><td> - </td><td> - </td></tr><tr><td> - </td><td> 488 nm Laser </td><td> Kohärent </td><td> - </td><td> Verwenden Sie bei minimalem Stromverbrauch </td></tr><tr><td> - </td><td> Verschluss </td><td> Uniblitz </td><td> - </td><td> - </td></tr><tr><td> VMM-D1 </td><td> Shutter-Treiber </td><td> Uniblitz </td><td> - </td><td> - </td></tr><tr><td> - </td><td> 561 nm Laser </td><td> Melles Griot </td><td> - </td><td> - </td></tr><tr><td> - </td><td> Verschluss </td><td> Uniblitz </td><td> - </td><td> - </td></tr><tr><td> VMM-D3 </td><td> Shutter-Treiber </td><td> Uniblitz </td><td> - </td><td> - </td></tr><tr><td> Perfusion Pressure Kit </td><td> Superfusion-System </td><td> Automatisieren Scientific </td><td> 09-04 </td><td> - </td></tr><tr><td> Perfusion Pen </td><td> Superfusion-System </td><td> Automatisieren Scientific </td><td> - </td><td> - </td></tr><tr><td> ValveLink 8 </td><td> Superfusion System Controller </td><td> Automatisieren Scientific </td><td> - </td><td> - </td></tr><tr><td> Cascade 512B </td><td> EM-CCD-Kamera </td><td> Roper Scientific </td><td> - </td><td> - </td></tr><tr><td> Metamorph 7,1 </td><td> Imaging Software </td><td> Molecular Devices </td><td> - </td><td> - </td></tr><tr><td> EPC-9 </td><td> Patch-Clamp-Verstärker </td><td> HEKA Elektronik </td><td> - </td><td> - </td></tr><tr><td> Puls </td><td> Verstärker Software </td><td> HEKA Elektronik </td><td> - </td><td> - </td></tr><tr><td> MP-285 </td><td> Mikromanipulator </td><td> Sutter Instrument </td><td> - </td><td> - </td></tr><tr><td> - </td><td> Elektrodenhalter </td><td> HEKA Elektronik </td><td> - </td><td> Für 1,5 mm OD Glas, 2 Stück </td></tr><tr><td> Kwik-Fil ® TW150-3 </td><td> Borosilikat Capillary Glass </td><td> WPI </td><td> - </td><td> Ohne Faden </td></tr><tr><td> B150-86 bis 10 </td><td> Borosilikat Capillary Glass </td><td> Sutter Instrument </td><td> - </td><td> Mit Filament </td></tr><tr><td> P-97 </td><td> Mikroelektroden-Puller </td><td> Sutter Instrument </td><td> - </td><td> Ausgestattet mit 3x3 Kästchen Filament-und Klimakammer </td></tr><tr><td> - </td><td> Pressure Vacuum Air Pump </td><td> Thomas Scientific </td><td> 7893B05 </td><td> Erstellt Vakuum, Flüssigkeiten von Kammer-und Überdruck für Pipetten entfernen </td></tr><tr><td> MatLab R2008a </td><td> Analyse-Software </td><td> MathWorks </td><td> - </td><td> - </td></tr><tr><td> 353001 </td><td> 35 mm Kunststoff-Petrischalen </td><td> Falke </td><td> - </td><td> - </td></tr><tr><td> - </td><td> High Refractive Index Glass </td><td> PlanOptik </td><td> - </td><td> Brechungsindex 488 nm = 1,78 </td></tr><tr><td> Serie M </td><td> High Refractive Index Flüssigkeit </td><td> Cargille Labs </td><td> - </td><td> Brechungsindex = 1,78 </td></tr><tr><td> Sylgard 184 </td><td> Silicon-Elastomer-Kit </td><td> Dow Corning </td><td> - </td><td> - </td></tr><tr><td> Glutathion </td><td> Tripeptide </td><td> EMD Chemicals </td><td></td><td> Kostenlose radical scavenger </td></tr><tr><td> Hyaluronidase </td><td> Enzym </td><td> Sigma </td><td> H6254 </td><td> Typ V </td></tr><tr><td> L-Cystein </td><td> Aminosäure </td><td> Fluka </td><td> 30090 </td><td> Aktiviert Papain </td></tr><tr><td> Papain </td><td> Enzym </td><td> Fluka </td><td> 76220 </td><td> Von Carica papaya </td></tr><tr><td> Trolox ® </td><td> Vitamin E </td><td> Sigma </td><td> 56510 </td><td> Radikalfänger </td></tr><tr><td> ADVASEP-7 </td><td> Sulfoniertes B-Cyclodextrin-Derivat </td><td> Sigma </td><td> A3723 </td><td> Reduziert FM 1-43 ® Hintergrundfluoreszenz </td></tr><tr><td> FM 1-43 ® </td><td> Fluoreszenzfarbstoff </td><td> Invitrogen </td><td> T35356 </td><td> &quot;Special Packaging&quot; </td></tr><tr><td> Sticky Wax </td><td> Pipette Beschichtungsmittel </td><td> Kerr Corporation </td><td> - </td><td> Verringert Pipette Kapazität </td></tr></tbody></table> Tabelle 2: Physiologische Lösungen in dieser Studie verwendet. <table border="1" cellspacing="0" cellpadding="0"><tbody><tr><td> Substanz </td><td> Low Ca 2 + Ringer- </td><td> Control-Ringer- </td><td> Hohe K + Ringer- </td><td> Interne Lösung </td></tr><tr><td> NaCl </td><td> 120 mM </td><td> 120 mM </td><td> 97,5 mm </td><td> - </td></tr><tr><td> KCl </td><td> 2,5 mM </td><td> 2,5 mM </td><td> 25 mM </td><td> - </td></tr><tr><td> MgCl 2 </td><td> 1 mM </td><td> 1 mM </td><td> 1 mM </td><td> 4 mM </td></tr><tr><td> CaCl 2 </td><td> 0,5 mM </td><td> 2,5 mM </td><td> 2,5 mM </td><td> - </td></tr><tr><td> HEPES </td><td> 10 mM </td><td> 10 mM </td><td> 10 mM </td><td> 10 mM </td></tr><tr><td> EGTA </td><td> 0,75 mM </td><td> - </td><td> - </td><td> 0,5 mM </td></tr><tr><td> Glucose </td><td> 10 mM </td><td> 10 mM </td><td> - </td><td> - </td></tr><tr><td> Glutathion </td><td> 2 mM </td><td> 2 mM </td><td> - </td><td> 1 mM </td></tr><tr><td> CH 3 CsO 3 S * </td><td> - </td><td> - </td><td> - </td><td> 100 mM </td></tr><tr><td> TEACl </td><td> - </td><td> - </td><td> - </td><td> 10 mM </td></tr><tr><td> ATP-Mg </td><td> - </td><td> - </td><td> - </td><td> 10 mM </td></tr><tr><td> GTP-Li </td><td> - </td><td> - </td><td> - </td><td> 1 mM </td></tr><tr><td> Rpep-rhod ** </td><td> - </td><td> - </td><td> - </td><td> 5 mM </td></tr><tr><td> Volumen </td><td> 200 mL </td><td> 100 mL </td><td> 5 ul </td><td> 100 ul </td></tr></tbody></table> * Cäsium Methansulfonat. ** RIBEYE-bindende Peptid: Rhodamin + EQTVPVDLSVARDR-COOH (mw 1.997,75).

<ol>
	<li>Axelrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Total+internal+reflection+fluorescence+microscopy+in+cell+biology.">Total internal reflection fluorescence microscopy in cell biology.</a> Traffic. 2, 764-774 (2001).</li><li>Zenisek, D., Steyer, J. A., Almers, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport,+capture+and+exocytosis+of+single+synaptic+vesicles+at+active+zones.">Transport, capture and exocytosis of single synaptic vesicles at active zones.</a> Nature. 406, 849-854 (2000).</li><li>Zenisek, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vesicle+association+and+exocytosis+at+ribbon+and+extraribbon+sites+in+retinal+bipolar+cell+presynaptic+terminals.">Vesicle association and exocytosis at ribbon and extraribbon sites in retinal bipolar cell presynaptic terminals.</a> Proc. Natl. Acad. Sci. U. S. A. 105, 4922-4927 (2008).</li><li>Zenisek, D., Horst, N. K., Merrifield, C., Sterling, P., Matthews, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualizing+synaptic+ribbons+in+the+living+cell.">Visualizing synaptic ribbons in the living cell.</a> J. Neurosci. 24, 9752-9759 (2004).</li><li>Axelrod, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+imaging+of+surface+fluorescence+with+very+high+aperture+microscope+objectives.">Selective imaging of surface fluorescence with very high aperture microscope objectives.</a> J. Biomed. Opt. 6, 6-13 (2001).</li><li>Rouze, N. C., Schwartz, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continous+and+transient+vesicle+cycling+at+a+ribbon+synapse.">Continous and transient vesicle cycling at a ribbon synapse.</a> J. Neurosci. 18, 8614-8624 (1998).</li></ol>

Die Vorteile der Ziel-Typ TIRF-Mikroskopie werden, dass 1) es hervorragende optische Schnitte bietet durch die Beschränkung Anregungslicht auf einen schmalen Bereich in der Brennebene des Objektivs und minimiert dadurch out-of-focus Licht, 2), da Licht fällt exponentiell mit der Entfernung kann eine Bewegung in vertikaler Richtung als eine Änderung in der Fluoreszenz-Intensität überwacht werden; 3) effiziente Lichtausbeute durch die hohe numerische Apertur Ziel 1,5. Der größte Nachteil dieser Technik ist, dass es z...

imaging exocytosis in retinal bipolar cells with tirf microscopy

Insgesamt internen Reflexion Fluoreszenz (TIRF)-Mikroskopie ist eine Technik, dass die Studie die Geschehnisse an der Zellmembran ermöglicht, durch selektive Darstellung von fluoreszierenden Molekülen, die zu einem hohen Brechungsindex Substanz wie Glas am nächsten sind,<sup&gt; 1</sup&gt;. In diesem Artikel wenden wir diese Technik, um Bild Exozytose synaptischer Vesikel in der Netzhaut bipolaren Zellen aus dem Goldfisch Netzhaut isoliert. Diese Neuronen sind sehr geeignet für diese Art der Studie aufgrund ihrer großen Axonterminalen. Durch die gleichzeitige Patch-Clamp der bipolaren Zellen, ist es möglich, die Beziehung zwischen präsynaptischen Spannung und synaptische Freisetzung untersuchen<sup&gt; 2,3</sup&gt;. Synaptischer Vesikel innerhalb der bipolaren Zellen Terminals sind mit einem Fluoreszenzfarbstoff (FM 1-43 ®) von geladenen Co-schnaufend dem Farbstoff und einem Ringer-Lösung mit einem hohen K<sup&gt; +</sup&gt; Konzentration auf die synaptischen Terminals. Dies depolarisiert die Zellen und regt die Endozytose und damit Farbstoffaufnahme in die glutamaterge Vesikel. Nach dem Waschen der überschüssige Farbstoff entfernt für etwa 30 Minuten werden die Zellen bereit für sein Patch gespannt und bebildert gleichzeitig mit einem 488 nm-Laser. Die Patch-Pipette Lösung enthält ein Rhodamin-basierte Peptid, das selektiv an den synaptischen Bandes Protein RIBEYE<sup&gt; 4</sup&gt;, Damit die Kennzeichnung Bänder speziell, wenn die Klemmen mit einem 561 nm Laser abgebildet werden. Dies ermöglicht die genaue Lokalisierung der aktiven Zonen und die Trennung von synaptischen aus extra-synaptischen Ereignisse.

Watch this Scientific Journal Video about Imaging Exocytosis in Retinal Bipolar Cells with TIRF Microscopy at JoVE.com

Imaging Exocytosis in Retinal Bipolar Cells with TIRF Microscopy

In diesem Video zeigen wir, wie Label und visualisieren einzelne synaptische Vesikel Exozytose und Menschenhandel in Goldfische Netzhaut bipolaren Zellen mit insgesamt internen Reflexion Fluoreszenz (TIRF)-Mikroskopie.

Imaging Exocytose in Retinal bipolaren Zellen mit TIRF-Mikroskopie

Total internal reflectance fluorescence (TIRF) microscopy is a technique that allows the study of events happening at the cell membrane, by selective ...

imaging-exocytosis-in-retinal-bipolar-cells-with-tirf-microscopy

Research

JoVE Journal

Biology

11.6K Aufrufe.  Yale University School of Medicine. In diesem Video zeigen wir, wie Label und visualisieren einzelne synaptische Vesikel Exozytose und Menschenhandel in Goldfische Netzhaut bipolaren Zellen mit insgesamt internen Reflexion Fluoreszenz (TIRF)-Mikroskopie.

Serie: Imaging Exocytosis in Retinal Bipolar Cells with TIRF Microscopy

Measuring Exocytosis in Neurons Using FM Labeling

The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission.  Here we used real-time imaging of vesicles labeled with FM dye to monitor the rate of presynaptic vesicle release.  FM4-64 is a red fluorescent amphiphilic styryl dye that embeds into the membranes of synaptic vesicles as endocytosis is stimulated.  Lipophilic interactions cause the dye to greatly increase in fluorescence, thus emitting a bright signal when associated with vesicles and a nominal one when in the extracellular fluid. After a wash step is used to help remove external dye within the plasma membrane, the remaining FM is concentrated within the vesicles and is then expelled when exocytosis is induced by another round of electrical stimulation. The rate of vesicles release is measured from the resulting decrease in fluorescence.  Since FM dye can be applied external and transiently, it is a useful tool for determining rates of exocytosis in neuronal cultures, especially when comparing the rates between transfected synapses and neighboring control boutons.



The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission. Here we used real-time imaging of vesicles labeled with the red fluorescent dye FM 4-64 to measure the rate of presynaptic vesicle release in hippocampal neuronal cultures.

Mess-Exocytose in Neuronen mit FM Labeling

The ability to measure the kinetics of vesicle release can help provide insight into some of the basics of neurotransmission.  Here we used real-time ...

Forschung

Biologie

Long-term Imaging Mammalian Cells using Wide-Field Microscopy

Actually what I'm gonna do, mount it in here first and then swap out You. So now I'm gonna aspirate try and be as gentle as possible.Okay. A few seconds just holding.Okay.Alright.So the important features of our lifestyle imaging grid are that, so it's an inverted scope, which means the objective, the samples here in the objective is underneath. So the objective is pointing up and the whole scope, or practically the whole, practically the whole scope, including the objectives and the sample are at 37 degrees. So everything in this plastic box is at 37 degrees.And right on top of the stage we have an air and CO2 mix. That is 5%CO2. So the idea is that the sample is actually in a cell, it's like a cell incubator.And so we have, this is our mixer for the air and the CO2 and, and it gets humidified and heated and then piped onto the, the sample on the stage.Okay. And today we're just gonna be doing fluorescence one channel GFP fluorescence. This is the hose that the CO2 and 5%CO2 goes in and it just fits into the stage holder.That's important. And then we can close these, take these down, and then we go to our first position. And what I'm gonna do is go to the first field, which is my control sample, and I'll pick positions based on what I see on the screen.So I just make sure I actually look into the microscope in each new, well, because the focal plane for each of the wells is different, the, the dish is not perfectly flat on the bottom. So you will need to make fine adjustments when you move from well to the well. So right now I'm on the first, well, what I'll do is I'll focus, so I just hit, I just told, I just turned on the light, the transmitted light for the microscope.And I have make sure all the light is going to the eye pieces. And so I just look in, make sure I get a nice clean field. And then what I'll do is turn that light off, turn the fluorescence light on, make sure the cells that I'm looking at look healthy and they're not apoptotic.And, and I turn that off. And what I do next is send, so now I'm gonna start picking positions, which means I have to te send the light path to the camera. This is the camera right here.So I tell the microscope to send all the camera, they don't see anything in the eye pieces. What I'll do is in the software controlling the microscope, I'll choose the right filter set, which for our purposes is psy. And then set an exposure time.And I know these cells very well and I know that they take a 0.2 second exposure time. So I tell, that's what I tell the software to do. And what I'll do is hit focus.This is, and it's basically just alive. The, A light will turn on and you can, oh, I don't know if you can see cells, but the reason this is a good field is because there's, all the cells are, even in terms of their fluorescence, There are no apoptotic cells. Apoptotic cells tend to be very bright and there's no dirt or schmutz in the field.And you can see that they're actually, this is a metaphase cell and that's a metaphase cell, that's a cell that's probably just exited mitosis. And I can just tell that because it looks like those are, those two sets of chromatin are very nicely oriented to each other. Like they just exited an face.So that's a good field. So, and now that I know that the exposure time and the filter set is correct, and this is gonna be software specific, I'll go and I'll take positions and now the software has memorized the X, Y, Z position of that field. And then when I do pick another field, it's, and I'll, so when I'm picking, when I'm picking new fields, but in the same, well, I'll use the, I'll move the i'll, I'll turn the shutter, I'll open the shutter and I'll look to see what I see on the screen and I'll pick fields based on that versus looking in the field.So I don't see any of my tonics in there. But again, even nicely centered, these cells will go through my PS I continue, here's a good example. Here's a good example of what I would avoid that, see how bright that is?That's very bright. That's probably remnants of an apoptotic cell. And the reason I would avoid that is because since it's so bright, when the software auto focuses, it will autofocus just on that and it won't be in the same plane as all these other cells.And so I won't get any information from that field. That looks nice. There's a, this is a pro metaphase right here, That's A metaphase.So, and I'm gonna take three positions per well. So that was three positions and now I'm going to go to my next Well, so you can, so what I will probably do is take images every 10 minutes. So it's a compromise.Lifestyle imaging is always a compromise, right? You have to image, you have to keep the cells healthy, especially if you're interested in mitosis. So you have to minimize their exposure to the fluorescent line.And, but you wanna get information. So you have to take images, you have to, so you have to compromise, you have to make a choice about what you want to capture, what kind of information you wanna capture. For our purposes, mitosis tends to take about an hour.So if we're taking 10 minute intervals, that's pretty good. We see prophase, we see metaphase, we see anaphase, and we can, we can see when there are, there are treatments or drugs or siRNAs that affect those specific cell cycle stages. So for our purposes, that's enough, but we always want more.We always want more positions or finer time and interval or something like that. So it's a compromise. So, and then I'll hit start.And so our software, it does an autofocusing pass on the first pass. So once I hit start, it should start auto autofocusing and you'll see the shutter open, open and close between auto focusing. So I'll hit start.So that's the shutter opening and closing. The Z motor is engaging and it's actually trying to find the plane with the most contrast, which will be the most in focus. You can actually see on the screen going in and out of finding the best plane of focus that might be worrisome.So what it does is it, it drives the Z motor to find the best, the most in focus plane focus, well the most in image. And then it acquires picture there and then it learns that Z position. And then we'll use that Z position for the next 12 passes.And then we'll do the auto focusing pass again. What Kind of experiments do they do? Okay, so our lab is mostly interested in understanding what regulates mitic progression, or at least I'm most interested in understanding that.So with live cell imaging and especially our multi position, long-term imaging scope, you can take, you can film cells for two or three days entering anding mitosis, and you can image multiple rounds of mitosis so you can understand. And then you can put drugs or RNAs or any kind of perturbations on the cells that you would like to study. So you can understand how, how those drugs or, or genes are, are important in regulating mitotic progression.Because it's not fixed cell work and live cell work, you can understand what, when you need to have a perturbation to affect mitosis or what stage of mitosis is affected. So it's really powerful in that respect. What, what are the main technical elements of this experiments?What are the possible problems? Well, the biggest problem besides getting the rig set up, getting the rig set up is not trivial. A lot of people have the rig, but just making sure it works well for your application.The financial element is not, you know, is not small. So there's the setting up of the apparatus and then, and then once you gather the data, there's a real data analysis issue. It takes these movie, if, so, if you're gathering 40 movies each with 30 cells, so you have 40 in 40 fields that you just filmed and each of those fields has 30 cells, then you have to sit down with each one of those movies and look at each one of those cells in that movie.So it takes a really long time to do data analysis. And that's, so it takes a week to analyze data that it took you two days to collect. So there's a, that's a very big obstacle in terms of gathering lots of data.So it's not, while it's high throughput data collection, it's not high throughput analysis. So what would you make to make this experiment really high throughput? So our lab is in the process of developing a program that does the data analysis automatically.And it's a pretty decent program. It's not perfect. The human eye is always better, but it's getting there.So What are the interesting application of this experiment? Maybe other fields you can mention? Besides cell division?You mean for the, oh, for the live cell imaging? Yes.Well, you can do cell motility assays. You can, depending on the, the microscopy that's involved, you can, you know, look at how cells, you could look at tumor development if you really wanted to.But there, you, you're, if as long as you have the right imaging set up, you can, you're pretty much not limited in terms of anything. Our scope happens to be just a wide field and we use 20 by 20 x objective. So it's a pretty low resolution set up, but that's sufficient for what we need to see.So there are, but there definitely aren't, you wouldn't be limited. Anything that has any dynamic kind of experiment, which is biology, it would be, would really benefit from lifestyle imaging. So calcium imaging, although you couldn't do it on our apparatus, that's a live cell.You definitely need live cell imaging for that. Like I said, patient assays, motility assays, those kinds of things would really benefit from live cell imaging. Would you like to tell a few words about your previous experience?How long do you work on these techniques? What do you you work on before? Wow.So in my PhD I didn't work.I did a lot of confocal microscopy, but no lifestyle imaging. And so during my postdoc I was, I helped Dr.King get this apparatus that, that we just used to set up these fragment, get that up and running. And, and so during my postdoc, I had a lot of experience with both widefield with TimeLapse imaging on our scope, which is the widefield and also TimeLapse imaging with confocal microscopy.And I would say that it's really powerful. You get a lot of information, but it's not easy to get working perfectly. So it really requires a lot of attention and a lot of attention to details at every little step of the process.And, and then you still have problems. So it's a tough application, but you can really get, if, if it's what you need to have to, to study your problem, your scientific problem, then it, it's invaluable in that respect, but it's tough. So find someone who knows what they're doing and use them.That's my advice. So good.

Langfristige Imaging Säugetierzellen mit Wide-Field-Mikroskopie

Time-lapse Imaging of Mitosis After siRNA Transfection

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and cellular content. Hallmark events of mitosis, such as chromosome movement, can be readily tracked on an individual cell basis using time-lapse fluorescence microscopy of mammalian cell lines expressing specific GFP-tagged proteins. In combination with RNAi-based depletion, this can be a powerful method for pinpointing the stage(s) of mitosis where defects occur after levels of a particular protein have been lowered. In this protocol, we present a basic method for assessing the effect of depleting a potential mitotic regulatory protein on the timing of mitosis. Cells are transfected with siRNA, placed in a stage-top incubation chamber, and imaged using an automated fluorescence microscope. We describe how to use software to set up a time-lapse experiment, how to process the image sequences to make either still-image montages or movies, and how to quantify and analyze the timing of mitotic stages using a cell-line expressing mCherry-tagged histone H2B. Finally, we discuss important considerations for designing a time-lapse experiment. This strategy is complementary to other approaches and offers the advantages of 1) sensitivity to changes in kinetics that might not be observed when looking at cells as a population and 2) analysis of mitosis without the need to synchronize the cell cycle using drug treatments. The visual information from such imaging experiments not only allows the sub-stages of mitosis to be assessed, but can also provide unexpected insight that would not be apparent from cell cycle analysis by FACS.

Here we describe a basic protocol to image and quantify the mitotic timing of live mammalian tissue culture cells after siRNA transfection.

Zeitraffer-Imaging der Mitose Nach siRNA-Transfektion

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and ...

Fluorescence-based Measurement of Store-operated Calcium Entry in Live Cells: from Cultured Cancer Cell to Skeletal Muscle Fiber

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to replenish depleted endoplasmic reticulum (ER) or sarcoplasmic reticulum (SR) Ca2+ stores1,2. Since Ca2+ is a ubiquitous second messenger, it is not surprising to see that SOCE plays important roles in a variety of cellular processes, including proliferation, apoptosis, gene transcription and motility. Due to its wide occurrence in nearly all cell types, including epithelial cells and skeletal muscles, this pathway has received great interest3,4. However, the heterogeneity of SOCE characteristics in different cell types and the physiological function are still not clear5-7.
The functional channel properties of SOCE can be revealed by patch-clamp studies, whereas a large body of knowledge about this pathway has been gained by fluorescence-based intracellular Ca2+ measurements because of its convenience and feasibility for high-throughput screening. The objective of this report is to summarize a few fluorescence-based methods to measure the activation of SOCE in monolayer cells, suspended cells and muscle fibers5,8-10. The most commonly used of these fluorescence methods is to directly monitor the dynamics of intracellular Ca2+ using the ratio of F340nm and F380nm (510 nm for emission wavelength) of the ratiometric Ca2+ indicator Fura-2. To isolate the activity of unidirectional SOCE from intracellular Ca2+ release and Ca2+ extrusion, a Mn2+ quenching assay is frequently used. Mn2+ is known to be able to permeate into cells via SOCE while it is impervious to the surface membrane extrusion processes or to ER uptake by Ca2+ pumps due to its very high affinity with Fura-2. As a result, the quenching of Fura-2 fluorescence induced by the entry of extracellular Mn2+ into the cells represents a measurement of activity of SOCE9. Ratiometric measurement and the Mn+2 quenching assays can be performed on a cuvette-based spectrofluorometer in a cell population mode or in a microscope-based system to visualize single cells. The advantage of single cell measurements is that individual cells subjected to gene manipulations can be selected using GFP or RFP reporters, allowing studies in genetically modified or mutated cells. The spatiotemporal characteristics of SOCE in structurally specialized skeletal muscle can be achieved in skinned muscle fibers by simultaneously monitoring the fluorescence of two low affinity Ca2+ indicators targeted to specific compartments of the muscle fiber, such as Fluo-5N in the SR and Rhod-5N in the transverse tubules9,11,12.

The extent of store-operated Ca2+ entry (SOCE) can be monitored using fluorescent Ca2+ indicators. Mn2+ quenching of such indicators assays SOCE in cultured cells and skeletal muscle fibers. A technique allowing spatial and temporal resolution of SOCE by confocal imaging of mechanically skinned muscle fibers is also described.

Fluoreszenz-basierte Messung von Calcium-Shop-Eintrag in lebenden Zellen: aus kultivierten Krebszelle zu Skelettmuskelfaser

Store operated Ca2+ entry (SOCE), earlier termed capacitative Ca2+ entry, is a tightly regulated mechanism for influx of extracellular Ca2+ into cells to ...

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) maintain the turnover of all mature blood cell lineages. The coordination of the complex signals leading to specific HSC fates relies upon the interaction between HSCs and the intricate bone marrow microenvironment, which is still poorly understood[1-2].
We describe how by combining a newly developed specimen holder for stable animal positioning with multi-step confocal and two-photon in vivo imaging techniques, it is possible to obtain high-resolution 3D stacks containing HSPCs and their surrounding niches and to monitor them over time through multi-point time-lapse imaging. High definition imaging allows detecting ex vivo labeled hematopoietic stem and progenitor cells (HSPCs) residing within the bone marrow. Moreover, multi-point time-lapse 3D imaging, obtained with faster acquisition settings, provides accurate information about HSPC movement and the reciprocal interactions between HSPCs and stroma cells.
Tracking of HSPCs in relation to GFP positive osteoblastic cells is shown as an exemplary application of this method. This technique can be utilized to track any appropriately labeled hematopoietic or stromal cell of interest within the mouse calvarium bone marrow space.

In Vivo 4-Dimensional Tracking of Hematopoietic Stem and Progenitor Cells in Adult Mouse Calvarial Bone Marrow

The nature of the interactions between hematopoietic stem and progenitor cells (HSPCs) and bone marrow niches is poorly understood. Custom hardware modifications and a multi-step acquisition protocol allow the use of two-photon and confocal microscopy to image ex vivo labeled HSPCs homed within bone marrow areas, tracking interactions and movement.

In-vivo-4-Dimensional-Tracking von hämatopoetischen Stamm-und Vorläuferzellen im erwachsenen Maus Schädeldachknochenmark

Through a delicate balance between quiescence and proliferation, self renewal and production of differentiated progeny, hematopoietic stem cells (HSCs) ...

Fluorescence Imaging with One-nanometer Accuracy (FIONA)

Fluorescence imaging with one-nanometer accuracy (FIONA) is a simple but useful technique for localizing single fluorophores with nanometer precision in the x-y plane. Here a summary of the FIONA technique is reported and examples of research that have been performed using FIONA are briefly described. First, how to set up the required equipment for FIONA experiments, i.e., a total internal reflection fluorescence microscopy (TIRFM), with details on aligning the optics, is described. Then how to carry out a simple FIONA experiment on localizing immobilized Cy3-DNA single molecules using appropriate protocols, followed by the use of FIONA to measure the 36 nm step size of a single truncated myosin Va motor labeled with a quantum dot, is illustrated. Lastly, recent effort to extend the application of FIONA to thick samples is reported. It is shown that, using a water immersion objective and quantum dots soaked deep in sol-gels and rabbit eye corneas (&#62;200 &#181;m), localization precision of 2-3 nm can be achieved.

Fluorescence Imaging with One-nanometer Accuracy FIONA

Single fluorophores can be localized with nanometer precision using FIONA. Here a summary of the FIONA technique is reported, and how to carry out FIONA experiments is described.

Fluoreszenz-Imaging mit One-Nanometer-Genauigkeit (FIONA)

Fluorescence imaging with one-nanometer accuracy (FIONA) is a simple but useful technique for localizing single fluorophores with nanometer precision in ...

Visualizing Clathrin-mediated Endocytosis of G Protein-coupled Receptors at Single-event Resolution via TIRF Microscopy

Many important signaling receptors are internalized through the well-studied process of clathrin-mediated endocytosis (CME). Traditional cell biological assays, measuring global changes in endocytosis, have identified over 30 known components participating in CME, and biochemical studies have generated an interaction map of many of these components. It is becoming increasingly clear, however, that CME is a highly dynamic process whose regulation is complex and delicate. In this manuscript, we describe the use of Total Internal Reflection Fluorescence (TIRF) microscopy to directly visualize the dynamics of components of the clathrin-mediated endocytic machinery, in real time in living cells, at the level of individual events that mediate this process. This approach is essential to elucidate the subtle changes that can alter endocytosis without globally blocking it, as is seen with physiological regulation. We will focus on using this technique to analyze an area of emerging interest, the role of cargo composition in modulating the dynamics of distinct clathrin-coated pits (CCPs). This protocol is compatible with a variety of widely available fluorescence probes, and may be applied to visualizing the dynamics of many cargo molecules that are internalized from the cell surface.

Clathrin-mediated endocytosis, a rapid and highly dynamic process internalizes many proteins, including signaling receptors. The protocol described here directly visualizes the kinetics of individual endocytic events. This is essential for understanding how core members of the endocytic machinery coordinate with each other, and how protein cargo influence this process.

Visualisierung Clathrin-vermittelte Endozytose von G-Protein-gekoppelten Rezeptoren an Einzelereignis Resolution über TIRF-Mikroskopie

Many important signaling receptors are internalized through the well-studied process of clathrin-mediated endocytosis (CME). Traditional cell biological ...

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.

Eine grafische Benutzeroberfläche für die softwaregestützte Verfolgung der Proteinkonzentration in dynamischen zellulären Vorsprüngen

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex ...

Imaging FITC-dextran as a Reporter for Regulated Exocytosis

Regulated exocytosis is a process by which cargo, which is stored in secretory granules (SGs), is released in response to a secretory trigger. Regulated exocytosis is fundamental for intercellular communication and is a key mechanism for the secretion of neurotransmitters, hormones, inflammatory mediators, and other compounds, by a variety of cells. At least three distinct mechanisms are known for regulated exocytosis: full exocytosis, where a single SG fully fuses with the plasma membrane, kiss-and-run exocytosis, where a single SG transiently fuses with the plasma membrane, and compound exocytosis, where several SGs fuse with each other, prior to or after SG fusion with the plasma membrane. The type of regulated exocytosis undertaken by a cell is often dictated by the type of secretory trigger. However, in many cells, a single secretory trigger can activate multiple modes of regulated exocytosis simultaneously. Despite their abundance and importance across cell types and species, the mechanisms that determine the different modes of secretion are largely unresolved. One of the main challenges in investigating the different modes of regulated exocytosis, is the difficulty in distinguishing between them as well as exploring them separately. Here we describe the use of fluorescein isothiocyanate (FITC)-dextran as an exocytosis reporter, and live cell imaging, to differentiate between the different pathways of regulated exocytosis, focusing on compound exocytosis, based on the robustness and duration of the exocytic events.

Here we detail a method for live cell imaging of regulated exocytosis. This method utilizes FITC-dextran, which accumulates in lysosome-related organelles, as a reporter. This simple method also allows distinguishing between different modes of regulated exocytosis in cells that are difficult to manipulate genetically.

Imaging-FITC-Dextran als Reporter für regulierte Exozytose

Regulated exocytosis is a process by which cargo, which is stored in secretory granules (SGs), is released in response to a secretory trigger. Regulated ...

Biological Sample Preparation by High-pressure Freezing, Microwave-assisted Contrast Enhancement, and Minimal Resin Embedding for Volume Imaging

The described sample preparation technique is designed to combine the best quality of ultrastructural preservation with the most suitable contrast for the imaging modality in a focused ion beam scanning electron microscope (FIB-SEM), which is used to obtain stacks of sequential images for 3D reconstruction and modelling. High-pressure freezing (HPF) allows close to native structural preservation, but the subsequent freeze substitution often does not provide sufficient contrast, especially for a bigger specimen, which is needed for high-quality imaging in the SEM required for 3D reconstruction. Therefore, in this protocol, after the freeze substitution, additional contrasting steps are carried out at room temperature. Although these steps are performed in a microwave, it is also possible to follow traditional bench processing, which requires longer incubation times.The subsequent embedding in minimal amounts of resin allows for faster and more precise targeting and preparation inside the FIB-SEM. This protocol is especially useful for samples that require preparation by high-pressure freezing for a reliable ultrastructural preservation but do not gain enough contrast during the freeze substitution for volume imaging using FIB-SEM. In combination with the minimal resin embedding, this protocol provides an efficient workflow for the acquisition of high-quality volume data.

Here we present a protocol for combining two sample processing techniques, high-pressure freezing and microwave-assisted sample processing, followed by minimal resin embedding for acquiring data with a focused ion beam scanning electron microscope (FIB-SEM). This is demonstrated using a mouse tibial nerve sample and Caenorhabditis elegans.

Biologische Probenvorbereitung durch Hochdruck gefrieren, Mikrowellen-gestützte Kontrastverstärkung und minimale Harz einbetten für Volume Imaging

The described sample preparation technique is designed to combine the best quality of ultrastructural preservation with the most suitable contrast for the ...