Name: in vivo neuronal calcium imaging in c. elegans
Uploaded: 2013-04-10T13:00:00
Description: Watch this Scientific Journal Video about In vivo Neuronal Calcium Imaging in C. elegans at JoVE.com

Flere personer bidratt i arbeidet er beskrevet i denne artikkelen. CVG bygget eksperimentelle oppsett, og LS, SHC, og CVG utført forsøkene. CVG og SHC skrev manuskriptet. Alle forfatterne senere deltok i revisjonsprosessen og godkjent den endelige kopien av manuskriptet. Vi takker Paul Sternberg for GCaMP belastning. Noen nematode stammer som brukes i dette arbeidet ble gitt av Caenorhabditis Genetics Center (CGC), som er finansiert av NIH National Center for Research Resources (NCRR). MATLAB bildeanalyse programmet ble tilpasset fra det som brukes i 18. Forfatterne ble støttet av Boston University og Massachusetts Life Sciences Center.

1. Optisk oppsett <ol><li> Bruk en standard forbindelse mikroskop med epifluorescence imaging evner. Vi bruker et Nikon Eclipse Ti-U invertert mikroskop med en Intensilight HG Illuminator. </li><li> For beste bilde og signalkvalitet bruke en høy forstørrelse, høy numerisk apertur mål. Vi bruker vanligvis en Nikon X60 1,4 NA neddyppingsobjektivet. I noen tilfeller er det mulig å bruke lavere forstørrelse (X40, X20) avhengig ekspresjon nivå av fluoroforen og signalstyrke. </li><li> Bruk en høy følsomhet avkjøl...

<ol>
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Genetisk kodet kalsium indikatorer har vært mye brukt i C. elegans nevrobiologi. Tallrike grupper har anvendt disse teknikkene for å studere respons av primære sensoriske nevroner på ytre stimuli som demonstrert her med ASJ responsen til et elektrisk felt. Prominent eksempler er følelsen av mekanisk berøring, bestemte kjemikalier, temperatur og en elektrisk 12 felt, 16-19. Aktivitet av interneuron og muskelceller har også blitt overvåket både som reaksjon på stimuli og i kontroll av dyrs at...

Her presenterer vi praktiske metoder for in vivo kalsium bildebehandling i C. elegans nerveceller. Utviklingen av genetisk kodede kalsium-sensitive fluoroforer med høyt signal-til-støy-forhold gjør C. elegans en forholdsvis grei og kostnadseffektivt system for måling av nevrofysiologi og aktivitet. Vår bildebehandling er gjort med en standard forbindelse mikroskop med wide-feltet fluorescens avbildning av lett tilgjengelige fluoroforer. Vi presenterer flere teknikker ansette ulike fluoroforer og ulike eksempler preparater, diskutere styrker og svakheter ved hver. Data blir deretter presentert fra to eksempel eksperimenter. En utmerket ytterligere ressurs på teknikkene som er beskrevet her kan bli funnet i WormBook, &quot;Imaging aktiviteten av nevroner og muskler&quot; av R. Kerr, ( <a href="http://www.wormbook.org" target="_blank">http://www.wormbook.org</a> ) 3. To store klasser av genetisktisk kodet fluorescerende kalsium journalister er ofte brukt i C. elegans: enkelt kanal GCaMP og FRET-baserte Cameleon. Vi vil beskrive metoder og vise eksempler for data generert av hver. GCaMP er basert på en modifisert grønt fluorescerende protein (GFP) som er følsom for den omgivende kalsiumkonsentrasjon. Dette oppnås ved fusjon av GFP og den høye kalsium affinitet protein kalmodulin, slik at bindingen av kalsium ved kalmodulin bringer GFP molekylet til en effektiv fluorescerende bekreftelse 2. De siste fremskritt i disse fluoroforer generere eksepsjonell signal størrelse med opptil 500% økning i fluorescens intensitet over en fysiologisk spekter av kalsium og rimelig rask kinetikk ~ 95 msek økning tid og ~ 650 msek desintegrasjonstid 4. Over relativt korte tidsperioder (minutter), kan disse store signaler tillate lavere oppløsning imaging (lavere forstørrelse), og gitt en veloppdragen initial baseline måling, negere nødvendigheten for kontinuerlig baseline eller komparative målinger. Cameleon har fordelen av å være en FRET-basert fluorofor som genererer en Proporsjonal måling sammenligner to uavhengige kanaler eller bølgelengder 1. Den består av to separate fluoroforer (cyan-og gul-utslipp selvlysende proteiner, CFP og YFP) forbundet med en calmodulin protein. Komplekset er belyst med blått lys (440 nm) som interesserer CFP. Bindingen av kalsium bringer fluoroforer tettere sammen, øker fluorescens resonans energi overføring (FRET) fra CFP (donor) til YFP (akseptorfasen) og forårsaker CFP utslipp (480 nm) for å redusere og YFP utslipp (535 nm) for å øke . Relative kalsiumnivåer måles som forholdet mellom den YFP / CFP intensitet. Cameleon kinetikk er tregere enn GCaMP, målt in vivo for å ha en stigningstid på ~ 1 sekund og en desintegrasjonstid på ~ 3 sek 5. Imidlertidforholdet motsatt bevegelige signaler øker signalet størrelse og kompenserer for en rekke mulige artefakter som skyldes endringer i fluorofor konsentrasjon, bevegelse eller fokus avdrift og bleking. Genetisk kodet fluorescerende reportere negere mye av prøveopparbeidelse nødvendig med eksogent administrert prober og C. elegans liten gjennomsiktig kroppen tillater bildebehandling i intakt dyret ved hjelp av enkle bredt felt fluorescens. De viktigste tekniske utfordringen i prøveopparbeidelse er derfor å trygt immobilisere dyrene. Det finnes en rekke forskjellige brukte teknikker hver med fordeler og ulemper. Ved hjelp av en farmakologisk middel å lamme dyrene er lett å implementere og tillater montering av flere dyr på en prepareringsåpning (Levamisole, et kolinerg agonist som forårsaker muskelvev å gripe brukes typisk 6). C. elegans kan også være fysisk immobilisert ved monterer dempå stiv 10% 7 agarose, 8. Dette minimerer tyngre dyrefysiologi, tillater langvarig imaging (timer) og gjenvinning av flere dyr, men er mer teknisk vanskelig. Begge disse teknikkene begrense fysisk tilgang til dyrene (som er under et dekkglass) og kan derfor bare brukes med visse eksperimentelle stimuli (slik som lys, temperatur, elektrisk felt eller laser skade). For stimuli der fysisk tilgang kreves, for eksempel berøring eller administrasjon av kjemikalier, har mange studier hell limt C. elegans på plass (med veterinær klasse lim) 9. Dette er teknisk mer krevende, er et enkelt dyr forberedelse og tillater ikke dyr utvinning. Endelig har mange microfluidic enheter vært ansatt som fysisk begrense C. elegans, kan bevare dyr fysiologi, slik eksponering for de fleste typer stimuli (avhengig av enheten design) og muliggjøre rask utveksling og gjenvinning av dyrene <sup&gt; 10, 11. Men MicroFluidics krever flere tekniske ferdigheter og evner innen design, fabrikasjon og gjennomføring. I immobilisert dyr aktivitet og stimulans respons kan vanligvis måles i sensorisk og interneurons. Aktivitet av motoriske nevroner krever mer sofistikerte teknikker for bildebehandling i bevegelse dyr. Her vil vi presentere detaljerte metoder ansette de to mest enkle teknikker for farmakologisk paralyzation og immobilisering med stiv agarose. Metodene som presenteres her kan brukes til å måle neuronal aktivitet og cellefysiologi i C. elegans. Vi gir et eksempel på hver: bruke GCaMP å måle den sensoriske respons av ASJ nervecelle til en ekstern elektrisk felt, og bruke Cameleon å måle den fysiologiske kalsium respons laser skade av et nevron. Disse eksempler viser de fordeler og ulemper ved de to typene fluoroforer og illustrere hva som er mulig med systemet.

<table border="1">
 <tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Eclipse Ti-U inverted 
 microscope</td>
 <td>Nikon</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Intensilight HG Illuminator</td>
 <td>Nikon</td>
 <td>C-HGFI</td>
 <td>Fluorescent light source</td>
 </tr>
 <tr>
 <td>CFI Plan Apo VC 60X Oil</td>
 <td>Nikon</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Optical table or 3'X3' optical 
 grade breadboard</td>
 <td>Thor Labs</td>
 <td>&nbsp;</td>
 <td>If an optical table is not used an 
 optical grade breadboard on a 
 solid laboratory bench should 
 suffice.</td>
 </tr>
 <tr>
 <td>Clara Interline Camera</td>
 <td>Andor 
 Technology</td>
 <td>&nbsp;</td>
 <td>High-sensitivity CCD camera</td>
 </tr>
 <tr>
 <td>wtGFP Longpass Emission</td>
 <td>Chroma Technology 
 Corp.</td>
 <td>41015</td>
 <td>GFP filter set for imaging GCaMP</td>
 </tr>
 <tr>
 <td>Filter 440 +/- 10 nm</td>
 <td>Chroma</td>
 <td>D440/20x EX</td>
 <td>excitation filter for cameleon</td>
 </tr>
 <tr>
 <td>Dichroic mirror &gt; 455 nm 
 longpass</td>
 <td>Chroma</td>
 <td>455DCLP BS</td>
 <td>microscope dichroic for cameleon 
 imaging</td>
 </tr>
 <tr>
 <td>Dichroic mirror &gt; 515 nm 
 longpass</td>
 <td>Chroma</td>
 <td>515DCLP BS</td>
 <td>dichroic mirror for cameleon 
 imaging</td>
 </tr>
 <tr>
 <td>Filter 535 +/- 15 nm</td>
 <td>Chroma</td>
 <td>D535/30m EM</td>
 <td>YFP emission filter</td>
 </tr>
 <tr>
 <td>Filter 480 +/- 20 nm</td>
 <td>Chroma</td>
 <td>D485/40m EM</td>
 <td>CFP emission filter</td>
 </tr>
 <tr>
 <td>Lens, 200 mm, Achromat</td>
 <td>Thor Labs</td>
 <td>AC508-200-A1</td>
 <td>Relay lens for FRET optics (3)</td>
 </tr>
 <tr>
 <td>Silver broadband mirror</td>
 <td>Thor Labs</td>
 <td>ME2S-P01</td>
 <td>FRET optics (2)</td>
 </tr>
 <tr>
 <td>NGM buffer</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Levamisole</td>
 <td>Sigma</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Polybead Microspheres</td>
 <td>Polysciences, Inc.</td>
 <td>08691-10, 2.5% by 
 volume, 50 nm 
 diameter</td>
 <td>polystyrene nanoparticles for C. 
 elegans immobilization</td>
 </tr>
 <tr>
 <td>Transgenic strain, Strain 
 gpa-9::GCaMP3(in pha-1; 
 him-5 bkg) </td>
 <td>Sternberg Lab</td>
 <td>Strain PS6388</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Transgenic strain, mec- 
 4::YC3.60</td>
 <td>Gabel Lab</td>
 <td>Strain CG1B</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>

in vivo neuronal calcium imaging in c. elegans

Hvalkveisen ormen C. elegans er en ideell modell organisme for relativt enkel, rimelig neuronal bildebehandling in vivo. Sine små transparent kropp og enkel, tillater godt karakterisert nervesystemet identifikasjon og fluorescens bildebehandling av enhver Nevron innenfor intakt dyret. Enkle immobilisering teknikker med minimal innvirkning på dyrets fysiologi gir ekstra time-lapse imaging. Utviklingen av genetisk kodede kalsium sensitive fluoroforer som Cameleon 1 og GCaMP 2 tillater in vivo avbildning av neuronal kalsium knyttet både celle fysiologi og neuronal aktivitet. Tallrike transgene stammer som uttrykker disse fluoroforer i bestemte nevroner er lett tilgjengelig eller kan bli konstruert ved hjelp av veletablerte teknikker. Her beskriver vi detaljerte prosedyrer for måling kalsium dynamikk innenfor en enkelt nervecelle i vivo ved hjelp av både GCaMP og Cameleon. Vi diskuterer fordeler og disadvantalderen både samt ulike metoder for prøveopparbeidelse (dyr immobilisering) og bildeanalyse. Endelig, presenterer vi resultater fra to eksperimenter: 1) Ved hjelp av GCaMP å måle sensorisk responsen for en spesifikk nervecelle til en ekstern elektrisk felt og 2) Bruk Cameleon å måle den fysiologiske kalsium respons av en nervecelle til traumatisk laser skade. Kalsium imaging teknikker som disse er brukt mye i C. elegans og har blitt utvidet til målinger i fritt bevegelige dyr, flere nevroner samtidig og sammenligning på tvers av genetiske bakgrunn. C. elegans presenterer en robust og fleksibelt system for in vivo neuronal avbildning med fordeler fremfor andre modellsystemer i teknisk enkelhet og kostnadseffektivitet.

Her presenterer vi resultater fra to separate eksperimenter. Den første benytter GCaMP å måle responsen av en spesifikk sensorisk nevron til en definert ytre stimuli, noe som gir et godt eksempel på hvordan fluorescerende kalsium reportere kan brukes til optisk overvåke neuronal aktivitet i intakte C. elegans. Den andre benytter Cameleon å måle intracellulær kalsium forbigående utløst innenfor et nevron i respons til spesifikke laser skade, og dermed viser hvordan kalsium fysiologi kan måles innenfor...

Watch this Scientific Journal Video about In vivo Neuronal Calcium Imaging in C. elegans at JoVE.com

In vivo Neuronal Calcium Imaging in C. elegans

Med sin lille transparent kropp, veldokumentert nevroanatomi og en rekke mottagelig genetiske teknikker og reagenser,<em&gt; C. elegans</em&gt; Gjør en ideell modell organisme for<em&gt; In vivo</em&gt; Neuronal bildebehandling ved hjelp av relativt enkle, rimelige teknikker. Her beskriver vi enkelt Nevron bildebehandling innen intakte voksne dyr ved hjelp genetisk kodet fluorescerende kalsium indikatorer.

In vivo Neuronal Kalsium Imaging i C. elegans

The nematode worm C. elegans is an ideal model organism  for relatively simple, low cost neuronal imaging in vivo. Its small transparent body and simple, ...

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Neuroscience

In vivo Neuronal Calcium Imaging in C. elegans

In vivo Laser Axotomy in C. elegans

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron is damaged by injury or disease, it may regenerate. Cell-intrinsic and extrinsic factors influence the ability of a neuron to regenerate and restore function. Recently, the nematode C. elegans has emerged as an excellent model organism to identify genes and signaling pathways that influence the regeneration of neurons1-6. The main way to initiate neuronal regeneration in C. elegans is laser-mediated cutting, or axotomy. During axotomy, a fluorescently-labeled neuronal process is severed using high-energy pulses. Initially, neuronal regeneration in C. elegans was examined using an amplified femtosecond laser5. However, subsequent regeneration studies have shown that a conventional pulsed laser can be used to accurately sever neurons in vivo and elicit a similar regenerative response1,3,7.
We present a protocol for performing in vivo laser axotomy in the worm using a MicroPoint pulsed laser, a turnkey system that is readily available and that has been widely used for targeted cell ablation. We describe aligning the laser, mounting the worms, cutting specific neurons, and assessing subsequent regeneration. The system provides the ability to cut large numbers of neurons in multiple worms during one experiment. Thus, laser axotomy as described herein is an efficient system for initiating and analyzing the process of regeneration.

In vivo Laser Axotomy in C. elegans

A protocol to cut neurons in C. elegans with a MicroPoint pulsed laser is presented. We describe setting up the system, immobilizing worms, and severing labeled neurons. Advantages include a relatively low-cost system and the ability to sever neuronal processes or ablate cells in vivo.

Neurons communicate with other cells via axons and dendrites, slender membrane extensions that contain pre- or post-synaptic specializations. If a neuron ...

Imaging Neuronal Responses in Slice Preparations of Vomeronasal Organ Expressing a Genetically Encoded Calcium Sensor

The vomeronasal organ (VNO) detects chemosensory signals that carry information about the social, sexual and reproductive status of the individuals within the same species 1,2. These intraspecies signals, the pheromones, as well as signals from some predators 3, activate the vomeronasal sensory neurons (VSNs) with high levels of specificity and sensitivity 4. At least three distinct families of G-protein coupled receptors, V1R, V2R and FPR 5-14, are expressed in VNO neurons to mediate the detection of the chemosensory cues. To understand how pheromone information is encoded by the VNO, it is critical to analyze the response profiles of individual VSNs to various stimuli and identify the specific receptors that mediate these responses.
The neuroepithelia of VNO are enclosed in a pair of vomer bones. The semi-blind tubular structure of VNO has one open end (the vomeronasal duct) connecting to the nasal cavity. VSNs extend their dendrites to the lumen part of the VNO, where the pheromone cues are in contact with the receptors expressed at the dendritic knobs. The cell bodies of the VSNs form pseudo-stratified layers with V1R and V2R expressed in the apical and basal layers respectively 6-8. Several techniques have been utilized to monitor responses of VSNs to sensory stimuli 4,12,15-19. Among these techniques, acute slice preparation offers several advantages. First, compared to dissociated VSNs 3,17, slice preparations maintain the neurons in their native morphology and the dendrites of the cells stay relatively intact. Second, the cell bodies of the VSNs are easily accessible in coronal slice of the VNO to allow electrophysiology studies and imaging experiments as compared to whole epithelium and whole-mount preparations 12,20. Third, this method can be combined with molecular cloning techniques to allow receptor identification.
Sensory stimulation elicits strong Ca2+ influx in VSNs that is indicative of receptor activation 4,21. We thus develop transgenic mice that express G-CaMP2 in the olfactory sensory neurons, including the VSNs 15,22. The sensitivity and the genetic nature of the probe greatly facilitate Ca2+ imaging experiments. This method has eliminated the dye loading process used in previous studies 4,21. We also employ a ligand delivery system that enables application of various stimuli to the VNO slices. The combination of the two techniques allows us to monitor multiple neurons simultaneously in response to large numbers of stimuli. Finally, we have established a semi-automated analysis pipeline to assist image processing.

The vomeronasal organ (VNO) detects intraspecies chemical signals that convey social and reproductive information. We have performed Ca2+ imaging experiments using transgenic mice expressing G-CaMP2 in VNO tissue. This approach allows us to analyze the complicated response patterns of the vomeronasal neurons to large numbers of pheromone stimuli.

Imaging neuronal Responses i Slice Produkter av vomeronasal Organ uttrykker en Genetisk Encoded Kalsium Sensor

The vomeronasal organ (VNO) detects chemosensory signals that carry information about the social, sexual and reproductive status of the individuals within ...

Automated Quantification of Synaptic Fluorescence in C. elegans

Synapse strength refers to the amplitude of postsynaptic responses to presynaptic neurotransmitter release events, and has a major impact on overall neural circuit function. Synapse strength critically depends on the abundance of neurotransmitter receptors clustered at synaptic sites on the postsynaptic membrane. Receptor levels are established developmentally, and can be altered by receptor trafficking between surface-localized, subsynaptic, and intracellular pools, representing important mechanisms of synaptic plasticity and neuromodulation. Rigorous methods to quantify synaptically-localized neurotransmitter receptor abundance are essential to study synaptic development and plasticity. Fluorescence microscopy is an optimal approach because it preserves spatial information, distinguishing synaptic from non-synaptic pools, and discriminating among receptor populations localized to different types of synapses. The genetic model organism Caenorhabditis elegans is particularly well suited for these studies due to the small size and relative simplicity of its nervous system, its transparency, and the availability of powerful genetic techniques, allowing examination of native synapses in intact animals.
Here we present a method for quantifying fluorescently-labeled synaptic neurotransmitter receptors in C. elegans. Its key feature is the automated identification and analysis of individual synapses in three dimensions in multi-plane confocal microscope output files, tabulating position, volume, fluorescence intensity, and total fluorescence for each synapse. This approach has two principal advantages over manual analysis of z-plane projections of confocal data. First, because every plane of the confocal data set is included, no data are lost through z-plane projection, typically based on pixel intensity averages or maxima. Second, identification of synapses is automated, but can be inspected by the experimenter as the data analysis proceeds, allowing fast and accurate extraction of data from large numbers of synapses. Hundreds to thousands of synapses per sample can easily be obtained, producing large data sets to maximize statistical power. Considerations for preparing C. elegans for analysis, and performing confocal imaging to minimize variability between animals within treatment groups are also discussed. Although developed to analyze C. elegans postsynaptic receptors, this method is generally useful for any type of synaptically-localized protein, or indeed, any fluorescence signal that is localized to discrete clusters, puncta, or organelles.
The procedure is performed in three steps: 1) preparation of samples, 2) confocal imaging, and 3) image analysis. Steps 1 and 2 are specific to C. elegans, while step 3 is generally applicable to any punctate fluorescence signal in confocal micrographs.

Automated Quantification of Synaptic Fluorescence in C. elegans

The abundance of neurotransmitter receptors clustered at synapses strongly influences synaptic strength. This method quantifies fluorescently-labeled neurotransmitter receptors in three dimensions with single-synapse resolution in C. elegans, allowing hundreds of synapses to be rapidly characterized within a single sample without distortions introduced by z-plane projection.

Automatisert Kvantifisering av Synaptic fluorescens i<em&gt; C. elegans</em

Synapse strength refers to the amplitude of postsynaptic responses to presynaptic neurotransmitter release events, and has a major impact on overall ...

In Vivo Imaging of Dauer-specific Neuronal Remodeling in C. elegans

The mechanisms controlling stress-induced phenotypic plasticity in animals are frequently complex and difficult to study in vivo. A classic example of stress-induced plasticity is the dauer stage of C. elegans. Dauers are an alternative developmental larval stage formed under conditions of low concentrations of bacterial food and high concentrations of a dauer pheromone. Dauers display extensive developmental and behavioral plasticity. For example, a set of four inner-labial quadrant (IL2Q) neurons undergo extensive reversible remodeling during dauer formation. Utilizing the well-known environmental pathways regulating dauer entry, a previously established method for the production of crude dauer pheromone from large-scale liquid nematode cultures is demonstrated. With this method, a concentration of 50,000 - 75,000 nematodes/ml of liquid culture is sufficient to produce a highly potent crude dauer pheromone. The crude pheromone potency is determined by a dose-response bioassay. Finally, the methods used for in vivo time-lapse imaging of the IL2Qs during dauer formation are described.

In Vivo Imaging of Dauer-specific Neuronal Remodeling in C. elegans

Following exposure to specific environmental stressors, the nematode Caenorhabditis elegans undergoes extensive phenotypic plasticity to enter into a stress-resistant &#8216;dauer&#8217; juvenile stage. We present methods for the controlled induction and imaging of neuroplasticity during dauer.

In vivo avbildning av Dauer-spesifikke nevronale ombygging i C. elegans

The mechanisms controlling stress-induced phenotypic plasticity in animals are frequently complex and difficult to study in vivo. A classic example of ...

In Vivo Functional Brain Imaging Approach Based on Bioluminescent Calcium Indicator GFP-aequorin

Functional in vivo imaging has become a powerful approach to study the function and physiology of brain cells and structures of interest. Recently a new method of Ca2+-imaging using the bioluminescent reporter GFP-aequorin (GA) has been developed. This new technique relies on the fusion of the GFP and aequorin genes, producing a molecule capable of binding calcium and&#160;&#8212; with the addition of its cofactor coelenterazine &#8212; emitting bright light that can be monitored through a photon collector. Transgenic lines carrying the GFP-aequorin gene have been generated for both mice and Drosophila. In Drosophila, the GFP-aequorin gene has been placed under the control of the GAL4/UAS binary expression system allowing for targeted expression and imaging within the brain. This method has subsequently been shown to be capable of detecting both inward Ca2+-transients and Ca2+-released from inner stores. Most importantly it allows for a greater duration in continuous recording, imaging at greater depths within the brain, and recording at high temporal resolutions (up to 8.3 msec). Here we present the basic method for using bioluminescent imaging to record and analyze Ca2+-activity within the mushroom bodies, a structure central to learning and memory in the fly brain.

In Vivo Functional Brain Imaging Approach Based on Bioluminescent Calcium Indicator GFP-aequorin

Here we present a novel Ca2+-imaging approach using a bioluminescent reporter. This approach uses a fused construct GFP-aequorin which binds to Ca2+ and emits light, eliminating the need for light excitation. Significantly this method permits long continuous imaging, access to deep brain structures and high temporal resolution.

I Vivo Functional Brain Imaging tilnærming basert på Bioluminescent Kalsium Indicator GFP-aequorin

Functional in vivo imaging has become a powerful approach to study the function and physiology of brain cells and structures of interest. Recently a new ...

Using an Adapted Microfluidic Olfactory Chip for the Imaging of Neuronal Activity in Response to Pheromones in Male C. Elegans Head Neurons

The use of calcium indicators has greatly enhanced our understanding of neural dynamics and regulation. The nematode Caenorhabditis elegans, with its completely mapped nervous system and transparent anatomy, presents an ideal model for understanding real-time neural dynamics using calcium indicators. In combination with microfluidic technologies and experimental designs, calcium-imaging studies using these indicators are performed in both free-moving and trapped animals. However, most previous studies utilizing trapping devices, such as the olfactory chip described in Chronis et al., have devices designed for use in the more common hermaphrodite, as the less common male is both morphologically and structurally dissimilar. An adapted olfactory chip was designed and fabricated for increased efficiency in male neuronal imaging with using young adult animals. A turn was incorporated into the worm loading port to rotate the animals and to allow for the separation of the individual neurons within a bilateral pair in 2D imaging. Worms are exposed to a controlled flow of odorant within the microfluidic device, as described in previous hermaphrodite studies. Calcium transients are then analyzed using the open-source software ImageJ. The procedure described herein should allow for an increased amount of male-based C. elegans calcium imaging studies, deepening our understanding of the mechanisms of sex-specific neuronal signaling.

Using an Adapted Microfluidic Olfactory Chip for the Imaging of Neuronal Activity in Response to Pheromones in Male C. Elegans Head Neurons

The use of an adapted &#34;olfactory chip&#34; for the efficient calcium imaging of C. elegans males is described here. Studies of male exposure to glycerol and a pheromone are also shown.

Bruke en tilpasset Microfluidic Olfactory Chip for avbilding av Neuronal aktivitet svar feromoner i mannlige C. Elegans hodet nerveceller

The use of calcium indicators has greatly enhanced our understanding of neural dynamics and regulation. The nematode Caenorhabditis elegans, with its ...

Two-photon Calcium Imaging in Neuronal Dendrites in Brain Slices

Calcium (Ca2+) imaging is a powerful tool to investigate the spatiotemporal dynamics of intracellular Ca2+ signals in neuronal dendrites. Ca2+ fluctuations can occur through a variety of membrane and intracellular mechanisms and play a crucial role in the induction of synaptic plasticity and regulation of dendritic excitability. Hence, the ability to record different types of Ca2+ signals in dendritic branches is valuable for groups studying how dendrites integrate information. The advent of two-photon microscopy has made such studies significantly easier by solving the problems inherent to imaging in live tissue, such as light scattering and photodamage. Moreover, through combination of conventional electrophysiological techniques with two-photon Ca2+ imaging, it is possible to investigate local Ca2+ fluctuations in neuronal dendrites in parallel with recordings of synaptic activity in soma. Here, we describe how to use this method to study the dynamics of local Ca2+ transients (CaTs) in dendrites of GABAergic inhibitory interneurons. The method can be also applied to studying dendritic Ca2+ signaling in different neuronal types in acute brain slices.

We present a method combining whole-cell patch-clamp recordings and two-photon imaging to record Ca2+ transients in neuronal dendrites in acute brain slices.

To-fotonet kalsium Imaging i Neuronal Dendrites i hjernen skiver

Calcium (Ca2+) imaging is a powerful tool to investigate the spatiotemporal dynamics of intracellular Ca2+ signals in neuronal dendrites. Ca2+ ...

Ratiometric Calcium Imaging of Individual Neurons in Behaving Caenorhabditis Elegans

It has become increasingly clear that neural circuit activity in behaving animals differs substantially from that seen in anesthetized or immobilized animals. Highly sensitive, genetically encoded fluorescent reporters of Ca2+ have revolutionized the recording of cell and synaptic activity using non-invasive optical approaches in behaving animals. When combined with genetic and optogenetic techniques, the molecular mechanisms that modulate cell and circuit activity during different behavior states can be identified.
Here we describe methods for ratiometric Ca2+ imaging of single neurons in freely behaving Caenorhabditis elegans worms. We demonstrate a simple mounting technique that gently overlays worms growing on a standard Nematode Growth Media (NGM) agar block with a glass coverslip, permitting animals to be recorded at high-resolution during unrestricted movement and behavior. With this technique, we use the sensitive Ca2+ reporter GCaMP5 to record changes in intracellular Ca2+ in the serotonergic Hermaphrodite Specific Neurons (HSNs) as they drive egg-laying behavior. By co-expressing mCherry, a Ca2+-insensitive fluorescent protein, we can track the position of the HSN within ~ 1 &#181;m and correct for fluctuations in fluorescence caused by changes in focus or movement. Simultaneous, infrared brightfield imaging allows for behavior recording and animal tracking using a motorized stage. By integrating these microscopic techniques and data streams, we can record Ca2+ activity in the C. elegans egg-laying circuit as it progresses between inactive and active behavior states over tens of minutes.

Ratiometric Calcium Imaging of Individual Neurons in Behaving Caenorhabditis Elegans

This protocol describes the use of genetically encoded Ca2+ reporters to record changes in neural activity in behaving Caenorhabditis elegans worms. &#8195;

Ratiometric kalsium avbilding av individuelle Neurons i oppfører seg Caenorhabditis Elegans

It has become increasingly clear that neural circuit activity in behaving animals differs substantially from that seen in anesthetized or immobilized ...

In Vivo Calcium Imaging of Lateral-line Hair Cells in Larval Zebrafish

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory stimuli that mechanically deflect apical protrusions called hair bundles. Deflection opens mechanotransduction (MET) channels in hair bundles, leading to an influx of cations, including calcium. This cation influx depolarizes the cell and opens voltage-gated calcium channels located basally at the hair-cell presynapse. In mammals, hair cells are encased in bone, and it is challenging to functionally assess these activities in vivo. In contrast, larval zebrafish are transparent and possess an externally located lateral-line organ that contains hair cells. These hair cells are functionally and structurally similar to mammalian hair cells and can be functionally assessed in vivo. This article outlines a technique that utilizes a genetically encoded calcium indicator (GECI), GCaMP6s, to measure stimulus-evoked calcium signals in zebrafish lateral-line hair cells. GCaMP6s can be used, along with confocal imaging, to measure in vivo calcium signals at the apex and base of lateral-line hair cells. These signals provide a real-time, quantifiable readout of both mechanosensation- and presynapse-dependent calcium activities within these hair cells. These calcium signals also provide important functional information regarding how hair cells detect and transmit sensory stimuli. Overall, this technique generates useful data about relative changes in calcium activity in vivo. It is less well-suited for quantification of the absolute magnitude of calcium changes. This in vivo technique is sensitive to motion artifacts. A reasonable amount of practice and skill are required for proper positioning, immobilization, and stimulation of larvae. Ultimately, when properly executed, the protocol outlined in this article provides a powerful way to collect valuable information about the activity of hair-cells in their natural, fully integrated states within a live animal.

The zebrafish is a model system that has many valuable features including optical clarity, rapid external development, and, of particular importance to the field of hearing and balance, externally located sensory hair cells. This article outlines how transgenic zebrafish can be used to assay both hair-cell mechanosensation and presynaptic function in toto.

I Vivo kalsium bildebehandling av Lateral linje hårcellene i larver sebrafisk

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory ...

Quantitative Approaches for Scoring in vivo Neuronal Aggregate and Organelle Extrusion in Large Exopher Vesicles in C. elegans

Toxicity of misfolded proteins and mitochondrial dysfunction are pivotal factors that promote age-associated functional neuronal decline and neurodegenerative disease across species. Although these neurotoxic challenges have long been considered to be cell-intrinsic, considerable evidence now supports that misfolded human disease proteins originating in one neuron can appear in neighboring cells, a phenomenon proposed to promote pathology spread in human neurodegenerative disease.
C. elegans adult neurons that express aggregating proteins can extrude large (~4 &#181;m) membrane-surrounded vesicles that can include the aggregated protein, mitochondria, and lysosomes. These large vesicles are called &#8220;exophers&#8221; and are distinct from exosomes (which are about 100x smaller and have different biogenesis). Throwing out cellular debris in exophers may occur by a conserved mechanism that constitutes a fundamental, but formerly unrecognized, branch of neuronal proteostasis and mitochondrial quality control, relevant to processes by which aggregates spread in human neurodegenerative diseases.
While exophers have been mostly studied in animals that express high copy transgenic mCherry within touch neurons, these protocols are equally useful in the study of exophergenesis using fluorescently tagged organelles or other proteins of interest in various classes of neurons.
Described here are the physical features of C. elegans exophers, strategies for their detection, identification criteria, optimal timing for quantitation, and animal growth protocols that control for stresses that can modulate exopher production levels. Together, details of protocols outlined here should serve to establish a standard for quantitative analysis of exophers across laboratories. This document seeks to serve as a resource in the field for laboratories seeking to elaborate molecular mechanisms by which exophers are produced and by which exophers are reacted to by neighboring and distant cells.

Quantitative Approaches for Scoring in vivo Neuronal Aggregate and Organelle Extrusion in Large Exopher Vesicles in C. elegans

This protocol describes approaches for detection and quantitation of large aggregate and/or organelle extrusions (~4 &#181;m) produced by C. elegans cells in the form of membrane-bound exophers. We describe strains, growth conditions, scoring criteria, timing, and microscopy considerations needed to facilitate dissection of this debris expulsion mechanism.