Diese Arbeit wurde unterstützt von NIH DK092408 und DK100227, Herst AJR wurde von T32-DK007013 unterstützt. Möchten die Autoren danken Dr. Julian A.T. Dow für die CapaR-GAL4 und c724-GAL4 Drosophila Bestände. Wir danken auch Jacob B. Anderson für die Unterstützung, die Aufrechterhaltung der experimenteller fliegen Kreuzungen.

Die Autoren haben nichts preisgeben.

Der Erfolg der Quantifizierung der pH-Wertich in Drosophila MTs hängt ganz von der Gesundheit der extrahierten MTs und die Qualität der Montage und Zerlegung (Abbildung A – C). So ist der sorgsame Umgang mit Gewebe wie beschrieben zwingend. Folien, die frisch in PLL beschichtet Folien wesentlich Hilfe MT Montage, wie sie neigen dazu, viel mehr Kleber als die zuvor ausgesetzt waren auf Lösung. Sorgfältige Montage hilft auch bei der Identifizier...

Das Ziel dieses Protokolls ist es, Quantifizierung von intrazellulären pH (pHi) mit einer genetisch codierte pH-Indikator (GEpHI) zu beschreiben und zeigen, wie diese Methode zur basolateralen H+ Transport in einem Modell Insekt (D. Beurteilung herangezogen werden können Melanogaster) renal Struktur, Malpighian Röhrchen (MT). MTs dienen als die Ausscheidungsorgane der Fruchtfliege und sind funktionell ähnlich der Säugetier-Nephron in einigen wesentlichen Punkten1. MTs sind als 2 Paare der Tubuli (Front- und Seitenzahnbereich) in den Thorax und Abdomen der Fliege angeordnet. Die einzelligen epitheliale Röhre von jeder MT besteht aus metabolisch aktiven wichtigsten Zellen mit deutlichen apikalen (luminalen) sowie basolateralen (Salzhaushalts) Polarität und eingefügten Ganglion Zellen. Vorderen MTs bestehen aus 3 morphologisch, funktionell und entwicklungsgeschichtlich verschiedene Segmente, vor allem die anfängliche geweitet, Segment, Übergangs-Segment und sekretorischen Hauptsegment, verbindet die Harnleiter-2. Auf der zellulären Ebene Trans-epithelialen Ionentransport in das Lumen wird erreicht, indem eine apikale Plasmamembran V-ATPase3 sowie eine Alkali-Metall/H+ -Wärmetauscher und einen basolateralen Na+-K+-ATPase4, nach innen-Gleichrichter-K+ Kanäle5, Na+-getrieben Cl−/HCO3− Wärmetauscher (NDAE1)6und Na+-K+-2 Cl− Cotransporter (NKCC; Ncc69)7, während Ganglion Zellen Cl– vermitteln und Wassertransport8,9. Dieses komplexe, aber zugänglich physiologische System bietet hervorragende Möglichkeiten zur Untersuchung der endogenen Ion Transportmechanismen in Kombination mit den vielfältigen genetischen und Verhaltensstörungen Toolsets von Drosophila.
Die Gründe für dieses Protokoll war ein genetisch formbar System für das Studium der epithelialen Ionentransport mit Potenzial für die Integration von Zelle zu Verhalten und Export von Werkzeugen zu Fremdsystemen Modell zu beschreiben. Ausdruck von pHerry10, erlaubt ein GEpHI abgeleitet aus einer Fusion von grünen pH-Sensitive Super-Ekliptik pHluorin11,12 (SEpH) und rote pH-unempfindliche mCherry13, in MTs Quantifizierung der H+ Transport in MT-Einzelzellen durch die hohe K+/nigericin Kalibrierung Technik14. Wie viele Ionen-Transporter H+ äquivalente bewegen, dient Quantifizierung der intrazellulären pHich als eine funktionelle Darstellung der Ionenbewegung über eine Vielzahl von Transportern. Die Drosophila MT-Modell-System bietet auch genetische Werkzeuge in gewebespezifischen Transgene15 und RNA-Interferenz (RNAi)16 Ausdruck, die zelluläre Bildgebung mit ganz-Orgel-Assays17 kombiniert werden können , 18 , 19 der Röhrchen-Funktion, erstellen Sie eine robusteste Toolset mit vertikalen Integration von Molekülen zu Verhalten. Dies steht im Gegensatz zu vielen anderen Protokollen zur Beurteilung epithelialen Biologie, wie historisch solche Messungen auf komplizierte verlassen haben und erschreckend, Mikro-Dissektion, anspruchsvolle ionenselektive Elektroden20,21, und teure pH-sensitiven Farbstoffen22 mit restriktiven laden Anforderungen und schlechte zelluläre Spezifität in heterogenen Geweben. GEpHIs wurden verwendet, um ausgiebig pHich in einer Vielzahl der Zelle Arten23messen. Frühwerk ausgenutzt die inhärente pH-Empfindlichkeit von Green Fluorescent Protein (GFP) pH-Wertich in kultivierten Epithelzellen24 überwachen, aber zwei Jahrzehnte habe GEpHIs verwendet in Neuronen25, Glia26, Pilze27 , und Pflanzenzellen28. Die Kombination des Potenzials für zelluläre targeting der genetischen Konstrukte durch die GAL4/UAS Ausdruck System15 und die physiologische Zugänglichkeit der Drosophila MT machen dies eine ideale Vorbereitung für Untersuchungen von pHich Regulierung und epithelialen Ionentransport.
pH-Wertesich wurde seit Jahrzehnten untersucht und ist lebenswichtig. Die MT-Vorbereitung bietet ein stabiles Modell zur Physiologie des pH-Wertesich Lehren aber auch anspruchsvolle Untersuchungen von pHi Verordnung ex-Vivo - und in Vivo. Dieses Protokoll beschreibt Quantifizierung der H+ -Bewegung in der basolateralen Membran der Epithelzellen der Drosophila MT mit NH4Cl Puls Säure laden Technik21, aber als pH-Indikator ist genetisch codiert, können diese Methoden und ihre theoretischen Rahmen zur Vorbereitung zu Transgenese und live-Imaging angewendet werden.

<table>
	<tbody>
		<tr>
			<td>Poly-L-Lysine Solution</td>
			<td>Sigma-Aldrich</td>
			<td>P4832</td>
			<td>Store at 4 &#176;C, can be reused.</td>
		</tr>
		<tr>
			<td>Nigericin Sodium Salt</td>
			<td>Sigma-Aldrich</td>
			<td>N7143</td>
			<td>CAUTION: Handle with gloves. Store as aliquots of 20 mM stock solution in DMSO at 4 &#176;C.</td>
		</tr>
		<tr>
			<td>Adhesive Perfusion Chamber Covers, adhesive size 1 mm, chamber diameter &#215; thickness 9 mm &#215; 0.9 mm, ports diameter 1.5 mm</td>
			<td>Sigma-Aldrich</td>
			<td>GBL622105</td>
			<td>Can be substituted as needed to match perfusion system.</td>
		</tr>
		<tr>
			<td>Sylgard 184 Silicone Elastomer Kit</td>
			<td>Ellsworth Adhesives</td>
			<td>184 SIL ELAST KIT 0.5KG</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Helping Hands Soldering Stands</td>
			<td>Harbor Freight Tools</td>
			<td>60501</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Open Gravity-fed Perfusion System with Valve Controller, 8 to 1 Manifold and Reserviors</td>
			<td>Bioscience Tools</td>
			<td>PS-8S</td>
			<td>Any comparable perfusion system can be used.</td>
		</tr>
		<tr>
			<td>Flow Regulator</td>
			<td>Warner Instruments</td>
			<td>64-0221</td>
			<td>Can be substituted as needed to match perfusion system.</td>
		</tr>
		<tr>
			<td>Schneider&#39;s Medium</td>
			<td>Fisher Scientific</td>
			<td>21720024</td>
			<td>Store at 4 &#176;C in sterile aliquots.</td>
		</tr>
		<tr>
			<td>#5 Inox Steel Forceps</td>
			<td>Fine Science Tools</td>
			<td>11252-20</td>
			<td>Can be substituted based on experimenter comfort.</td>
		</tr>
		<tr>
			<td>35 mm x 10 mm polystyrene Petri dish</td>
			<td>Corning Life Sciences</td>
			<td>Fisher Scientific 08-757-100A</td>
			<td>Exact brand and size are unimportant.</td>
		</tr>
		<tr>
			<td>75 x 25 mm Microscope Slides</td>
			<td>Corning Life Sciences</td>
			<td>2949-75X25</td>
			<td>Exact brand and size can vary as long as perfusion wells are compatible.</td>
		</tr>
		<tr>
			<td>Filimented Borosilicate Capillary Glass, ID 1.5 mm, OD 0.86 mm, thickness 0.32 mm</td>
			<td>Warner Instruments</td>
			<td>64-0796</td>
			<td>Filiment not necessary, glass can be substituted to match perfusion tubing and perfusion wells.</td>
		</tr>
		<tr>
			<td>Tygon Tubing, ID 1/16 inch, OD 1/8 inch, thickness 1/32 inch</td>
			<td>Fisher Scientific</td>
			<td>14-171-129</td>
			<td>Available from multiple vendors, can be substituted to match perfusion system.</td>
		</tr>
		<tr>
			<td>Vacuum Silicone Grease</td>
			<td>Sigma-Aldrich</td>
			<td>Z273554</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Plastic Flow Control Clamp</td>
			<td>Fisher Scientific</td>
			<td>05-869</td>
			<td>Available from multiple vendors, sterility not required</td>
		</tr>
		<tr>
			<td>Glass rods, 5 mm diameter</td>
			<td>delphiglass.com</td>
			<td>9198</td>
			<td>Exact size is personal preference, multiple vendors available</td>
		</tr>
		<tr>
			<td>PAP Hydrophobic Pen</td>
			<td>Sigma-Aldrich</td>
			<td>Z377821</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Sealing Film</td>
			<td>Sigma-Aldrich</td>
			<td>P7668</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>15 mL Falcon tube</td>
			<td>BD Falcon</td>
			<td>352096</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>50 mL Falcon tube</td>
			<td>BD Falcon</td>
			<td>352070</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>HEPES; 4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid</td>
			<td>Sigma-Aldrich</td>
			<td>H3375</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>MES; 4-Morpholineethanesulfonic acid monohydrate</td>
			<td>Sigma-Aldrich</td>
			<td>69892</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>TAPS; N-[Tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid</td>
			<td>Sigma-Aldrich</td>
			<td>T5130</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>10x/0.45 Air Objective</td>
			<td>Zeiss</td>
			<td>000000-1063-139</td>
			<td>Comparable objectives can be substituted. 40x objectives can be used for single cell imaging.</td>
		</tr>
		<tr>
			<td>Dissecting Stereoscope</td>
			<td>Zeiss</td>
			<td>Discovery.V8</td>
			<td>Any dissecting stereoscope can be used.</td>
		</tr>
		<tr>
			<td>UAS-pHerry transgenic Drosophila melagnogaster</td>
			<td>Available from Romero Lab</td>
			<td></td>
			<td>First published: Citation 10</td>
		</tr>
		<tr>
			<td>capaR-GAL4 driver line Drosophila melagnogaster</td>
			<td>Available from Romero Lab</td>
			<td></td>
			<td>First published: Citation 32</td>
		</tr>
		<tr>
			<td>c724-GAL4 driver line Drosophila melagnogaster</td>
			<td>Available from Romero Lab</td>
			<td></td>
			<td>First published: Citation 2</td>
		</tr>
		<tr>
			<td>Monochromatic High Sensitivity Digital Camera</td>
			<td>Zeiss</td>
			<td>Axiocam 506 mono</td>
			<td>Exact brand and model can vary, can be replaced with any monochromatic high-sensitivity camera suited to live cellular imaging.</td>
		</tr>
		<tr>
			<td>GFP/FITC filter set, 470/40 nm ex., 515 nm longpass em., 500 nm dichroic</td>
			<td>Chroma</td>
			<td>CZ909</td>
			<td>Any GFP/FITC filer set can be substituted.</td>
		</tr>
		<tr>
			<td>RFP/TRITC filter set, 546/10 nm ex., 590 nm longpass em., 565 nm dichroic</td>
			<td>Chroma</td>
			<td>CZ915</td>
			<td>Any GFP/FITC filer set can be substituted.</td>
		</tr>
		<tr>
			<td>Inverted Epifluoescent Microscope</td>
			<td>Zeiss</td>
			<td>Axio Observer Z.1</td>
			<td>Any comparable microscope with motorized filter switching can be used. Upright microscopes can be used with open perfusion baths and water-immersion objectives.</td>
		</tr>
		<tr>
			<td>Statistical Analysis Software</td>
			<td>Microcal</td>
			<td>Origin 6.0</td>
			<td>Any software with comparable functionality can be substituted</td>
		</tr>
		<tr>
			<td>Image Analysis Software</td>
			<td>National Institutes of Health</td>
			<td>ImageJ 1.50i</td>
			<td>Any software with comparable functionality can be substituted</td>
		</tr>
		<tr>
			<td>Image Acquisition Software</td>
			<td>Zeiss</td>
			<td>Zen 1.1.2.0</td>
			<td>Any software with comparable functionality can be substituted</td>
		</tr>
		<tr>
			<td>Single-edged Carbon Steel Razor Blade</td>
			<td>Electron Microscopy Sciences</td>
			<td>71960</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Microscopy Slide Folder</td>
			<td>Fisher Scientific</td>
			<td>16-04</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Bunsen Burner</td>
			<td>Fisher Scientific</td>
			<td>50-110-1231</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>Polystrene Drosophila Rearing Vials with Flugs</td>
			<td>Genesee Scientific</td>
			<td>32-109BF</td>
			<td>Comparable items can be substituted.</td>
		</tr>
		<tr>
			<td>2.5 L Laboratory Ice Bucket</td>
			<td>Fisher Scientific</td>
			<td>07-210-129</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>NMDG; N-Methyl-D-glucamine</td>
			<td>Sigma-Aldrich</td>
			<td>M2004</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>200 uL barrier pipette tips</td>
			<td>MidSci</td>
			<td>AV200</td>
			<td>Available from multiple vendors.</td>
		</tr>
		<tr>
			<td>200 uL variable volume pipette</td>
			<td>Gilson Incorporated</td>
			<td>PIPETMAN P200</td>
			<td>Available from multiple vendors.</td>
		</tr>
	</tbody>
</table>

optical quantification of intracellular ph in drosophila melanogaster malpighian tubule epithelia with a fluorescent genetically-encoded ph indicator

Epitheliale Ionentransport unbedingt systemische Ion Homöostase sowie Wartung von wesentliche zelluläre elektrochemischen Gradienten. Intrazelluläre pH-Wert (pHich) wird von vielen Ionen-Transporter beeinflusst und somit pHich Überwachung ist ein nützliches Werkzeug für die Beurteilung der Transporter Aktivität. Moderne genetisch codierte pH-Indikatoren (GEpHIs) bieten optische Quantifizierung der pH-Wertich in intakten Zellen auf zellulärer und subzellulärer Ebene. Dieses Protokoll beschreibt in Echtzeit Quantifizierung der zellulärenich pH-Wertes in Malpighian Tubuli (MTs) von Drosophila Melanogaster durch ex-Vivo Leben-Bildgebung von pHerry, ein Pseudo-ratiometrischen GEpHI mit einem p-Kein gut geeignet zum Nachverfolgen von Änderungen der pH-Wert in der Zellflüssigkeit. Extrahierten Erwachsenen Fliege MTs bestehen aus morphologisch und funktionell unterschiedliche Abschnitte der einzellige Schicht Epithelien und dient als Modell für die Untersuchung von epithelialen Transport zugänglich und genetisch gefügig. GEpHIs bieten mehrere Vorteile gegenüber herkömmlichen pH-Sensitive fluoreszierende Farbstoffe und ionenselektive Elektroden. GEpHIs können unterschiedliche Zellpopulationen beschriften, sofern entsprechende Promotor Elemente verfügbar sind. Diese Kennzeichnung ist besonders nützlich in ex Vivo, in Vivound in Situ Präparate, die von Natur aus heterogen sind. GEpHIs erlauben auch die Quantifizierung der pHi im intakten Gewebe im Laufe der Zeit ohne Notwendigkeit einer Behandlung oder Gewebe Externalisierung wiederholte Farbstoff. Der Hauptnachteil des aktuellen GEpHIs ist die Tendenz zu aggregieren in cytosolischen Einschlüssen in Reaktion auf Gewebeschäden und Überexpression zu konstruieren. Diese Mängel, Lösungen und die Vorteile des GEpHIs werden in diesem Protokoll durch Bewertung der basolateralen (H+) Protonentransport in funktionell unterschiedliche Haupt- und Ganglion Zellen der extrahierten Fliege MTs demonstriert. Die Techniken und Analyse beschrieben sind leicht anpassbar an eine Vielzahl von Wirbeltieren und Wirbellosen Vorbereitungen und die Raffinesse des Assays kann von der Lehre Labs, um komplizierte Bestimmung der Ionen-Fluss über spezifische Transporter skaliert werden.

Gesundes Gewebe und korrekte Kennzeichnung der vorderen MTs sind entscheidend für den Erfolg dieses Protokolls. Während der Dissektion sollte darauf geachtet werden, nicht direkt berühren die MTs und einzige Griff führt sie durch den Harnleiter als greifen die MTs direkt zum Bruch (– Abbildung 4A B). Wenn MTs flach auf der Folie gekehrt werden, die Tubuli darf so wenig wie möglich berührt werden und überflüssige Bew...

Watch this Scientific Journal Video about Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator at JoVE.

Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator

Zelluläre Ionentransport durch die Überwachung der intrazellulären pH-Wert oft beurteilt werden kann (pHich(). Genetisch bieten codiert pH-Indikatoren (GEpHIs) optische Quantifizierung von intrazellulären pH in intakten Zellen. Dieses Protokoll beschreibt die Quantifizierung von intrazellulären pH durch zelluläre ex Vivo Leben-Bildgebung von Malpighian Tubuli von Drosophila Melanogaster mit pHerry, ein Pseudo-ratiometrischen genetisch codiert pH-Indikator.

Optische Quantifizierung der intrazellulären pH in Drosophila Melanogaster Malpighian Röhrchen Epithelien mit einem fluoreszierenden genetisch codierte pH Indikator

Epithelial ion transport is vital to systemic ion homeostasis as well as maintenance of essential cellular electrochemical gradients. Intracellular pH ...

optical-quantification-intracellular-ph-drosophila-melanogaster

Research

JoVE Journal

Biology

Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator

10.1K Aufrufe.  Mayo Clinic College of Medicine. Zelluläre Ionentransport durch die Überwachung der intrazellulären pH-Wert oft beurteilt werden kann (pHich(). Genetisch bieten codiert pH-Indikatoren (GEpHIs) optische Quantifizierung von intrazellulären pH in intakten Zellen. Dieses Protokoll beschreibt die Quantifizierung von intrazellulären pH durch zelluläre ex Vivo Leben-Bildgeb...

Serie: Optical Quantification of Intracellular pH in Drosophila melanogaster Malpighian Tubule Epithelia with a Fluorescent Genetically-encoded pH Indicator

Dissection of Larval CNS in Drosophila Melanogaster

The central nervous system (CNS) of Drosophila larvae is complex and poorly understood.  One way to investigate the CNS is to use immunohistochemistry to examine the expression of various novel and marker proteins.  Staining of whole larvae is impractical because the tough cuticle prevents antibodies from penetrating inside the body cavity.  In order to stain these tissues it is necessary to dissect the animal prior to fixing and staining.  In this article we demonstrate how to dissect Drosophila larvae without damaging the CNS.  Begin by tearing the larva in half with a pair of fine forceps, and then turn the cuticle "inside-out" to expose the CNS.  If the dissection is performed carefully the CNS will remain attached to the cuticle.  We usually keep the CNS attached to the cuticle throughout the fixation and staining steps, and only completely remove the CNS from the cuticle just prior to mounting the samples on glass slides.  We also show some representative images of a larval CNS stained with Eve, a transcription factor expressed in a subset of neurons in the CNS.  The article concludes with a discussion of some of the practical uses of this technique and the potential difficulties that may arise.

In this article we demonstrate how to dissect the central nervous system from third instar Drosophila larvae.

Dissection der Larven ZNS von Drosophila melanogaster

The central nervous system (CNS) of Drosophila larvae is complex and poorly understood.  One way to investigate the CNS is to use immunohistochemistry to ...

Forschung

Biologie

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained and restrained whole larvae. For direct control of the environment around the heart another approach utilizes the dissected larvae and removal of the internal organs in order to bathe the heart in desired compounds. The exposed heart also allows membrane potentials to be monitored which can give insight of the ionic currents generated by the myocytes and for electrical conduction along the heart tube. These approaches have various advantages and disadvantages for future experiments that are discussed. The larval heart preparation provides an additional model besides the Drosophila skeletal NMJ to investigate the role of intracellular calcium regulation on cellular function. Learning more about the underlying ionic currents that shape the action potentials in myocytes in various species, one can hope to get a handle on the known ionic dysfunctions associated to specific genes responsible for various diseases in mammals.

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various ways to monitor heart function in the larva of Drosophila for assessing questions dealing with the function of gap junctions, ion channel mutations, modulation of pacemaker activity and pharmacological studies.

Überwachung Herzfunktion Larven Drosophila melanogaster Für physiologische Untersuchungen

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained  and  ...

Monitoring Dynamic Changes In Mitochondrial Calcium Levels During Apoptosis Using A Genetically Encoded Calcium Sensor

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, differentiation, and apoptosis1. During apoptosis, calcium accumulation in mitochondria promotes the release of pro-apoptotic factors from the mitochondria into the cytosol2. It is therefore of interest to directly measure mitochondrial calcium in living cells in situ during apoptosis. High-resolution fluorescent imaging of cells loaded with dual-excitation ratiometric and non-ratiometric synthetic calcium indicator dyes has been proven to be a reliable and versatile tool to study various aspects of intracellular calcium signaling. Measuring cytosolic calcium fluxes using these techniques is relatively straightforward. However, measuring intramitochondrial calcium levels in intact cells using synthetic calcium indicators such as rhod-2 and rhod-FF is more challenging. Synthetic indicators targeted to mitochondria have blunted responses to repetitive increases in mitochondrial calcium, and disrupt mitochondrial morphology3. Additionally, synthetic indicators tend to leak out of mitochondria over several hours which makes them unsuitable for long-term experiments. Thus, genetically encoded calcium indicators based upon green fluorescent protein (GFP)4 or aequorin5 targeted to mitochondria have greatly facilitated measurement of mitochondrial calcium dynamics. Here, we describe a simple method for real-time measurement of mitochondrial calcium fluxes in response to different stimuli. The method is based on fluorescence microscopy of 'ratiometric-pericam' which is selectively targeted to mitochondria. Ratiometric pericam is a calcium indicator based on a fusion of circularly permuted yellow fluorescent protein and calmodulin4. Binding of calcium to ratiometric pericam causes a shift of its excitation peak from 415 nm to 494 nm, while the emission spectrum, which peaks around 515 nm, remains unchanged. Ratiometric pericam binds a single calcium ion with a dissociation constant in vitro of ~1.7 &mu;M4. These properties of ratiometric pericam allow the quantification of rapid and long-term changes in mitochondrial calcium concentration. Furthermore, we describe adaptation of this methodology to a standard wide-field calcium imaging microscope with commonly available filter sets. Using two distinct agonists, the purinergic agonist ATP and apoptosis-inducing drug staurosporine, we demonstrate that this method is appropriate for monitoring changes in mitochondrial calcium concentration with a temporal resolution of seconds to hours. Furthermore, we also demonstrate that ratiometric pericam is also useful for measuring mitochondrial fission/fragmentation during apoptosis. Thus, ratiometric pericam is particularly well suited for continuous long-term measurement of mitochondrial calcium dynamics during apoptosis.

This protocol describes a method for real-time measurement of mitochondrial calcium fluxes by fluorescent imaging. The method takes advantage of a circularly permutated YFP-based dual-excitation ratiometric calcium sensor (ratiometric pericam-mt) selectively expressed in mitochondria.

Überwachung dynamischen Veränderungen in der mitochondrialen Kalzium während der Apoptose mit einem genetisch kodierten Kalzium-Sensor

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, ...

Measurement of Lifespan in Drosophila melanogaster

Aging is a phenomenon that results in steady physiological deterioration in nearly all organisms in which it has been examined, leading to reduced physical performance and increased risk of disease. Individual aging is manifest at the population level as an increase in age-dependent mortality, which is often measured in the laboratory by observing lifespan in large cohorts of age-matched individuals. Experiments that seek to quantify the extent to which genetic or environmental manipulations impact lifespan in simple model organisms have been remarkably successful for understanding the aspects of aging that are conserved across taxa and for inspiring new strategies for extending lifespan and preventing age-associated disease in mammals.
The vinegar fly, Drosophila melanogaster, is an attractive model organism for studying the mechanisms of aging due to its relatively short lifespan, convenient husbandry, and facile genetics. However, demographic measures of aging, including age-specific survival and mortality, are extraordinarily susceptible to even minor variations in experimental design and environment, and the maintenance of strict laboratory practices for the duration of aging experiments is required. These considerations, together with the need to practice careful control of genetic background, are essential for generating robust measurements. Indeed, there are many notable controversies surrounding inference from longevity experiments in yeast, worms, flies and mice that have been traced to environmental or genetic artifacts1-4. In this protocol, we describe a set of procedures that have been optimized over many years of measuring longevity in Drosophila using laboratory vials. We also describe the use of the dLife software, which was developed by our laboratory and is available for download (<a href="http://sitemaker.umich.edu/pletcherlab/software">http://sitemaker.umich.edu/pletcherlab/software</a>). dLife accelerates throughput and promotes good practices by incorporating optimal experimental design, simplifying fly handling and data collection, and standardizing data analysis. We will also discuss the many potential pitfalls in the design, collection, and interpretation of lifespan data, and we provide steps to avoid these dangers.

Measurement of Lifespan in Drosophila melanogaster

Drosophila melanogaster is a powerful model organism for exploring the molecular basis of longevity regulation. This protocol will discuss the steps involved in generating a reproducible, population-based measurement of longevity as well as potential pitfalls and how to avoid them.

Messung der Lebensdauer in<em&gt; Drosophila melanogaster</em

Aging is a phenomenon that results in steady physiological deterioration in nearly all organisms in which it has been examined, leading to reduced ...

Measurement of Vacuolar and Cytosolic pH In Vivo in Yeast Cell Suspensions

Vacuolar and cytosolic pH are highly regulated in yeast cells and occupy a central role in overall pH homeostasis. We describe protocols for ratiometric measurement of pH in vivo using pH-sensitive fluorophores localized to the vacuole or cytosol. Vacuolar pH is measured using BCECF, which localizes to the vacuole in yeast when introduced into cells in its acetoxymethyl ester form. Cytosolic pH is measured with a pH-sensitive GFP expressed under control of a yeast promoter, yeast pHluorin. Methods for measurement of fluorescence ratios in yeast cell suspensions in a fluorimeter are described. Through these protocols, single time point measurements of pH under different conditions or in different yeast mutants have been compared and changes in pH over time have been monitored. These methods have also been adapted to a fluorescence plate reader format for high-throughput experiments. Advantages of ratiometric pH measurements over other approaches currently in use, potential experimental problems and solutions, and prospects for future use of these techniques are also described.

Measurement of Vacuolar and Cytosolic pH In Vivo in Yeast Cell Suspensions

Vacuolar and cytosolic pH can be measured in live yeast (S. cerevisiae) cells using ratiometric fluorescent dyes localized to specific cellular compartments. We describe procedures for measuring vacuolar pH with BCECF-AM, which localizes to the vacuole in yeast, and cytosolic pH with a cytosolic ratiometric pH-sensitive GFP (yeast pHluorin).

Messung von pH Vacuolar und Cytosolic<em&gt; In Vivo</em&gt; In Hefe Zellsuspensionen

Vacuolar and  cytosolic pH are highly regulated in yeast cells and occupy a central role in  overall pH homeostasis. We describe  protocols for ...

Genetically-encoded Molecular Probes to Study G Protein-coupled Receptors

To facilitate structural and dynamic studies of G protein-coupled receptor (GPCR) signaling complexes, new approaches are required to introduce informative probes or labels into expressed receptors that do not perturb receptor function. We used amber codon suppression technology to genetically-encode the unnatural amino acid, p-azido-L-phenylalanine (azF) at various targeted positions in GPCRs heterologously expressed in mammalian cells. The versatility of the azido group is illustrated here in different applications to study GPCRs in their native cellular environment or under detergent solubilized conditions. First, we demonstrate a cell-based targeted photocrosslinking technology to identify the residues in the ligand-binding pocket of GPCR where a tritium-labeled small-molecule ligand is crosslinked to a genetically-encoded azido amino acid. We then demonstrate site-specific modification of GPCRs by the bioorthogonal Staudinger-Bertozzi ligation reaction that targets the azido group using phosphine derivatives. We discuss a general strategy for targeted peptide-epitope tagging of expressed membrane proteins in-culture and its detection using a whole-cell-based ELISA approach. Finally, we show that azF-GPCRs can be selectively tagged with fluorescent probes. The methodologies discussed are general, in that they can in principle be applied to any amino acid position in any expressed GPCR to interrogate active signaling complexes.

We genetically-encode the unnatural amino acid, p-azido-L-phenylalanine at various targeted positions in GPCRs and show the versatility of the azido group in different applications. These include a targeted photocrosslinking technology to identify residues in the ligand-binding pocket of a GPCR, and site-specific bioorthogonal modification of GPCRs with a peptide-epitope tag or fluorescent probe.

Genetisch kodierte Molecular Probes, um G-Protein-gekoppelte Rezeptoren Studieren

To facilitate structural and dynamic studies of G protein-coupled receptor (GPCR) signaling complexes, new approaches are required to introduce ...

Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule

Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The Drosophila&#160;melanogaster Malpighian (renal) tubule offers an unparalleled opportunity to study the molecular mechanisms of epithelial ion transport, due to the powerful genetics of this organism and the accessibility of its renal tubules to physiological study. Here, we describe the use of the Ramsay assay to measure fluid secretion rates from isolated fly renal tubules, with the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid. This assay allows study of transepithelial fluid and ion fluxes of ~20 tubules at a time, without the need to transfer the secreted fluid to a separate apparatus to measure ion concentrations. Genetically distinct tubules can be analyzed to assess the role of specific genes in transport processes. Additionally, the bathing saline can be modified to examine the effects of its chemical characteristics, or drugs or hormones added. In summary, this technique allows the molecular characterization of basic mechanisms of epithelial ion transport in the Drosophila tubule, as well as regulation of these transport mechanisms.

Use of the Ramsay Assay to Measure Fluid Secretion and Ion Flux Rates in the Drosophila melanogaster Malpighian Tubule

This protocol describes the use of the Ramsay assay to measure fluid secretion rates from isolated Malpighian (renal) tubules from Drosophila melanogaster. In addition, the use of ion-specific electrodes to measure sodium and potassium concentrations in the secreted fluid, allowing calculation of transepithelial ion flux, is described.

Die Nutzung der Ramsay Assay zu Flüssigkeitssekretion und Ionenfluss Preise in der Maßnahme<em&gt; Drosophila melanogaster</em&gt; Malpighischen Tubulus

Modulation of renal epithelial ion transport allows organisms to maintain ionic and osmotic homeostasis in the face of varying external conditions. The ...

Maintenance of a Drosophila melanogaster Population Cage

Large quantities of DNA, RNA, proteins and other cellular components are often required for biochemistry and molecular biology experiments. The short life cycle of Drosophila enables collection of large quantities of material from embryos, larvae, pupae and adult flies, in a synchronized way, at a low economic cost. A major strategy for propagating large numbers of flies is the use of a fly population cage. This useful and common tool in the Drososphila community is an efficient way to regularly produce milligrams to tens of grams of embryos, depending on uniformity of developmental stage desired. While a population cage can be time consuming to set up, maintaining a cage over months takes much less time and enables rapid collection of biological material in a short period. This paper describes a detailed and flexible protocol for the maintenance of a Drosophila melanogaster population cage, starting with 1.5 g of harvested material from the previous cycle.

Maintenance of a Drosophila melanogaster Population Cage

This manuscript reports a detailed protocol for culturing, on a regular basis, a population of Drosophila melanogaster using a fly population cage.

Aufrechterhaltung eines<em&gt; Drosophila melanogaster</em&gt; Bevölkerung Cage

Large quantities of DNA, RNA, proteins and other cellular components are often required for biochemistry and molecular biology experiments. The short life ...

Application of Genetically Encoded Fluorescent Nitric Oxide (NO&#8226;) Probes, the geNOps, for Real-time Imaging of NO&#8226; Signals in Single Cells

Nitric Oxide (NO&#8226;) is a small radical, which mediates multiple important cellular functions in mammals, bacteria and plants. Despite the existence of a large number of methods for detecting NO&#8226; in vivo and in vitro, the real-time monitoring of NO&#8226; at the single-cell level is very challenging. The physiological or pathological effects of NO&#8226; are determined by the actual concentration and dwell time of this radical. Accordingly, methods that allow the single-cell detection of NO&#8226; are highly desirable. Recently, we expanded the pallet of NO&#8226; indicators by introducing single fluorescent protein-based genetically encoded nitric oxide (NO&#8226;) probes (geNOps) that directly respond to cellular NO&#8226; fluctuations and, hence, addresses this need. Here we demonstrate the usage of geNOps to assess intracellular NO&#8226; signals in response to two different chemical NO&#8226;-liberating molecules. Our results also confirm that freshly prepared 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC-7) has a much higher potential to evoke change in intracellular NO&#8226; levels as compared with the inorganic NO&#8226; donor sodium nitroprusside (SNP). Furthermore, dual-color live-cell imaging using the green geNOps (G-geNOp) and the chemical Ca2+ indicator fura-2 was performed to visualize the tight regulation of Ca2+-dependent NO&#8226; formation in single endothelial cells. These representative experiments demonstrate that geNOps are suitable tools to investigate the real-time generation and degradation of single-cell NO&#8226; signals in diverse experimental setups.

This manuscript presents protocols for the application of novel genetically encoded nitric oxide (NO&#8226;) probes (geNOps) to monitor single cell NO&#8226; fluctuations in real-time using fluorescence microscopy. The Ca2+-triggered NO&#8226; formation on the level of individual endothelial cells was visualized by combining geNOps with a chemical Ca2+ sensor.

Die Anwendung von genetisch kodierter Fluorescent Stickstoffmonoxid (NO) • Sonden, die geNOps, für Echtzeit-Imaging von NO • Signale in Einzelzellen

Nitric Oxide (NO&#8226;) is a small radical, which mediates multiple important cellular functions in mammals, bacteria and plants. Despite the existence ...

Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles

Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight muscles (IFMs) of flies, specifically the dorso-longitudinal muscles (DLM), as the experimental subject to measure the atrophic phenotype brought about by different genetic causes. In this protocol, we describe how to embed fly thorax muscles for semi thin sectioning, how to obtain a good contrast between muscle and the surrounding tissue, and how to process optical microscope images for semiautomatic acquisition of quantifiable data and analysis. We describe three specific applications of the methodological pipeline. First, we show how the method can be applied to quantify muscle degeneration in a myotonic dystrophy fly model; second, measurement of muscle cross-sectional area can help to identify genes that either promote or prevent muscle atrophy and/or muscle degeneration; third, this protocol can be applied to determine whether a candidate compound is able to significantly modify a given atrophic phenotype induced by a disease-causing mutation or by an environmental trigger.

Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles

We report a method to quantify muscle area, which is an indirect method to determine muscle mass in Drosophila adults. We demonstrate the application of our methodology by analyzing the indirect flight muscles in a Drosophila model of Myotonic Dystrophy disease.

Optische Cross-sectional Muskel Bereich Bestimmung von Drosophila Melanogaster Erwachsenen indirekten Flugmuskeln

Muscle mass wasting, known as muscle atrophy, is a common phenotype in Drosophila models of neuromuscular diseases. We have used the indirect flight ...