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

Plusieurs personnes ont contribué aux travaux décrits dans le présent document. CVG a construit le dispositif expérimental, et LS, SHC, et CVG a effectué les expériences. CVG et SHC a écrit le manuscrit. Tous les auteurs par la suite participé au processus de révision et approuvé la version finale du manuscrit. Nous remercions Paul Sternberg pour la souche GCaMP. Certaines souches de nématodes utilisées dans ce travail ont été fournies par le Centre de Caenorhabditis Genetics (CCG), qui est financé par le NIH Centre National de Ressources de recherche (NCRR). Le programme MATLAB analyse d&#39;image a été adaptée de celle utilisée dans 18 ans. Les auteurs ont été pris en charge par l&#39;Université de Boston et le Massachusetts Life Sciences Center.

1. Configuration optique <ol><li> Utiliser un microscope composé standard avec des capacités d&#39;imagerie à épifluorescence. Nous utilisons un Nikon Eclipse Ti-U microscope inversé avec un illuminateur Intensilight HG. </li><li> Pour une meilleure qualité d&#39;image et du signal utiliser un fort grossissement, objectif haute ouverture numérique. Nous utilisons généralement un Nikon X60 1.4 Objectif NA immersion dans l&#39;huile. Dans certains cas, il est possible d&#39;utiliser plus faible grossissement (X...

<ol>
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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+the+AFD+neuron+in+C.+elegans+thermotaxis+analyzed+using+femtosecond+laser+ablation.">The role of the AFD neuron in C. elegans thermotaxis analyzed using femtosecond laser ablation.</a> BMC Neurosci. 7, 30 (2006).</li><li>Nagai, T., Yamada, S., Tominaga, T., Ichikawa, M., Miyawaki, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expanded+dynamic+range+of+fluorescent+indicators+for+Ca(2+)+by+circularly+permuted+yellow+fluorescent+proteins.">Expanded dynamic range of fluorescent indicators for Ca(2+) by circularly permuted yellow fluorescent proteins.</a> Proc. Natl. Acad. Sci. U.S.A. 101, 10554-10559 (2004).</li><li>Kindt, K. S., Quast, K. B., Giles, A. C., De, S., Hendrey, D., Nicastro, I., Rankin, C. H., Schafer, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dopamine+mediates+context-dependent+modulation+of+sensory+plasticity+in+C.+elegans.">Dopamine mediates context-dependent modulation of sensory plasticity in C. elegans.</a> Neuron. 55, 662-676 (2007).</li><li>Chalasani, S. H., Chronis, N., Tsunozaki, M., Gray, J. M., Ramot, D., Goodman, M. B., Bargmann, C. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissecting+a+circuit+for+olfactory+behaviour+in+Caenorhabditis+elegans.">Dissecting a circuit for olfactory behaviour in Caenorhabditis elegans.</a> Nature. 450, 63-70 (2007).</li><li>Clark, D. A., Gabel, C. V., Gabel, H., Samuel, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temporal+activity+patterns+in+thermosensory+neurons+of+freely+moving+Caenorhabditis+elegans+encode+spatial+thermal+gradients.">Temporal activity patterns in thermosensory neurons of freely moving Caenorhabditis elegans encode spatial thermal gradients.</a> J. Neurosci. 27, 6083-6090 (2007).</li><li>Biron, D., Shibuya, M., Gabel, C., Wasserman, S. M., Clark, D. A., Brown, A., Sengupta, P., Samuel, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+diacylglycerol+kinase+modulates+long-term+thermotactic+behavioral+plasticity+in+C.+elegans.">A diacylglycerol kinase modulates long-term thermotactic behavioral plasticity in C. elegans.</a> Nat. Neurosci. 9, 1499-1505 (2006).</li><li>Ghosh-Roy, A., Wu, Z. L., Goncharov, A., Jin, Y. S., Chisholm, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calcium+and+Cyclic+AMP+Promote+Axonal+Regeneration+in+Caenorhabditis+elegans+and+Require+DLK-1+Kinase.">Calcium and Cyclic AMP Promote Axonal Regeneration in Caenorhabditis elegans and Require DLK-1 Kinase.</a> Journal of Neuroscience. 30, 3175-3183 (2010).</li><li>Bianchi, L., Gerstbrein, B., Frokjaer-Jensen, C., Royal, D. C., Mukherjee, G., Royal, M. A., Xue, J., Schafer, W. R., Driscoll, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neurotoxic+MEC-4(d)+DEG/ENaC+sodium+channel+conducts+calcium:+implications+for+necrosis+initiation.">The neurotoxic MEC-4(d) DEG/ENaC sodium channel conducts calcium: implications for necrosis initiation.</a> Nat. Neurosci. 7, 1337-1344 (2004).</li></ol>

Indicateurs de calcium génétiquement codés ont été largement utilisés dans C. elegans neurobiologie. De nombreux groupes ont utilisé ces techniques pour étudier la réponse des neurones sensoriels primaires à des stimuli externes comme démontré ici avec la réponse ASJ à un champ électrique. Exemples les plus notables figurent sensation du toucher mécanique, des produits chimiques spécifiques, de la température et un champ électrique 12, 16-19. L&#39;activité des interneurones et le...

Nous présentons ici des méthodes pratiques pour l&#39;imagerie in vivo de calcium dans C. neurones elegans. Le développement de la codés génétiquement sensible au calcium avec une grande fluorophores signal sur bruit rend C. elegans un système relativement simple et rentable pour la mesure de la neurophysiologie et de l&#39;activité. Notre formation d&#39;image est effectuée avec un microscope standard à l&#39;aide d&#39;imagerie à grand champ de fluorescence des fluorophores couramment disponibles. Nous présentons plusieurs techniques employant différents fluorophores et la préparation des échantillons différents, de discuter les forces et les faiblesses de chacun. Les données sont ensuite présentées à partir de deux expériences exemple. Une excellente ressource supplémentaire sur les techniques décrites ici peuvent être trouvés dans WormBook, &quot;Imagerie l&#39;activité des neurones et les muscles&quot; de R. Kerr, ( <a href="http://www.wormbook.org" target="_blank">http://www.wormbook.org</a> ) 3. Deux grandes classes d&#39;génétiquementment codées reporters fluorescents de calcium sont couramment utilisés dans C. elegans: GCaMP seul canal et FRET à base de cameleon. Nous allons décrire les méthodes et montrer des exemples de données générés par chacun. GCaMP est basé sur une modification de la protéine fluorescente verte (GFP) qui est sensible à la concentration de calcium environnante. Ceci est réalisé par fusion de la GFP et de la calmoduline de calcium de haute affinité protéine, de telle sorte que la fixation du calcium par la calmoduline de la molécule apporte une confirmation dans la GFP efficace fluorescent 2. Les récents progrès dans ces fluorophores générer taille exceptionnelle du signal avec une augmentation jusqu&#39;à 500% de l&#39;intensité de fluorescence dans une gamme physiologique de la calcémie et de la cinétique relativement rapide de ~ 95 ms de temps de montée et temps de descente ~ 650 msec 4. Sur des périodes de temps relativement courtes (minutes), ces signaux peuvent permettre grandes pour l&#39;imagerie basse résolution (faible grossissement) et, étant donné un sage init amesure de référence ial, nier la nécessité pour base continue ou mesures comparatives. Cameleon a l&#39;avantage d&#39;être un fluorophore FRET basée sur une mesure qui génère ratiométrique comparaison de deux canaux indépendants ou longueurs d&#39;onde 1. Il se compose de deux fluorophores séparés (cyan et jaune émettant des protéines fluorescentes, CFP et YFP) reliés par une protéine calmoduline. Le complexe est éclairé par la lumière bleue (440 nm) qui excite la PCP. Fixation du calcium apporte les fluorophores se rapprocher, ce qui augmente le transfert d&#39;énergie de fluorescence par résonance (FRET) à partir de la PCP (donneur) de la YFP (accepteur) et provoquer l&#39;émission de la PCP (480 nm) et pour diminuer l&#39;émission YFP (535 nm) pour augmenter . Le taux de calcium relatifs sont mesurés par le rapport de l&#39;intensité de la YFP / PCP. Cameleon cinétique est plus lente que celle de GCaMP, mesurée in vivo pour avoir un temps de montée d&#39;environ 1 s et un temps de décroissance de 3 ~ 5 sec. Cependant,le rapport des signaux en opposition mobiles augmente la taille du signal et pour compenser un certain nombre d&#39;objets possibles à cause de changements de concentration en fluorophore, de mouvement ou de la dérive et de mise au point de blanchiment. Génétiquement codés rapporteurs fluorescents annuler une grande partie de la préparation des échantillons avec des sondes exogènes administrées et C. elegans petit corps transparent permet l&#39;imagerie chez l&#39;animal intact en utilisant de simples fluorescence large champ. Le principal défi technique dans la préparation des échantillons est donc d&#39;immobiliser les animaux en toute sécurité. Il ya un certain nombre de différentes techniques couramment utilisées chacune avec des avantages et des inconvénients. L&#39;utilisation d&#39;un agent pharmacologique de paralyser les animaux est facile à mettre en œuvre et permet le montage de plusieurs animaux sur une préparation (lévamisole, un agoniste cholinergique qui provoque le tissu musculaire à saisir est généralement utilisé 6). C. elegans peut aussi être physiquement immobilisé par leur montagele raide 10% d&#39;agarose 7, 8. Cet impact réduit sur la physiologie des animaux, permet à long terme d&#39;imagerie (heures) et la récupération de plusieurs animaux, mais est techniquement plus difficile. Ces deux techniques limiter l&#39;accès physique aux animaux (qui sont sous une lamelle) et ne peut donc être utilisé avec certains stimuli expérimentaux (tels que la lumière, la température, champ électrique ou de dommage au laser). Pour les stimuli où l&#39;accès physique est nécessaire, comme le toucher ou l&#39;administration de produits chimiques, de nombreuses études ont réussi à coller C. elegans en place (en utilisant de la colle d&#39;vétérinaire) 9. Ce qui est techniquement plus difficile, est une préparation unique animal et ne permet pas la récupération des animaux. Enfin, de nombreux dispositifs microfluidiques ont été employées que physiquement contre C. elegans, la préservation de la physiologie animale, ce qui permet une exposition à la plupart des types de stimuli (en fonction de la conception du dispositif) et peut permettre l&#39;échange rapide et de récupération des animaux <sup&gt; 10, 11. Cependant microfluidique besoin d&#39;autres compétences techniques et des capacités dans la conception, la fabrication et la mise en œuvre. L&#39;activité animaux immobilisés et de relance de réponse peut généralement être mesurée en sensoriels et des interneurones. L&#39;activité des neurones moteurs nécessite des techniques plus sophistiquées d&#39;imagerie chez l&#39;animal en mouvement. Ici, nous allons présenter les méthodes détaillées utilisant les deux techniques les plus simples de la paralysie pharmacologique et immobilisation rigide agarose. Les méthodes présentées ici peuvent être utilisés pour mesurer l&#39;activité neuronale et la physiologie des cellules de C. elegans. Nous donnons un exemple de chaque: en utilisant GCaMP pour mesurer la réponse du neurone sensoriel ASJ à un champ électrique externe, et en utilisant cameleon pour mesurer la réponse physiologique au calcium endommagement laser d&#39;un neurone. Ces exemples montrent les avantages et les inconvénients des deux types de fluorophores et d&#39;illustrer ce qui est possible avec le système.

<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

Le ver nématode C. elegans est un organisme modèle idéal pour relativement simple, l&#39;imagerie à faible coût neuronale in vivo. Son petit corps transparentes et simples, bien caractérisé le système nerveux permet l&#39;identification et l&#39;imagerie de fluorescence d&#39;un neurone à l&#39;intérieur de l&#39;animal intact. Techniques d&#39;immobilisation simples avec un impact minimal sur la physiologie de l&#39;animal permettent prolongée imagerie time-lapse. Le développement de fluorophores calcium génétiquement encodés sensibles tels que cameleon 1 et 2 GCaMP permettre l&#39;imagerie in vivo de calcium neuronal concernant la physiologie cellulaire et l&#39;activité neuronale. De nombreuses souches transgéniques exprimant ces fluorophores dans des neurones spécifiques sont facilement disponibles ou peuvent être construits en utilisant des techniques bien établies. Ici, nous décrivons des procédures détaillées pour la mesure dynamique du calcium dans un seul neurone in vivo en utilisant à la fois GCaMP et caméléon. Nous discutons des avantages et des disadvantles âges de deux, ainsi que diverses méthodes de préparation des échantillons (immobilisation des animaux) et l&#39;analyse d&#39;image. Enfin, nous présentons les résultats de deux expériences: 1) Utilisation GCaMP pour mesurer la réponse d&#39;un neurone sensoriel spécifique à un champ électrique externe et 2) Utilisation cameleon pour mesurer la réponse physiologique de calcium d&#39;un neurone à l&#39;endommagement laser traumatique. Techniques d&#39;imagerie calcique comme ceux-ci sont largement utilisés dans C. elegans et ont été étendues aux mesures chez les animaux se déplaçant librement, les neurones multiples simultanément et de comparaison entre fonds génétiques. C. elegans présente un système robuste et flexible pour l&#39;imagerie neuronale in vivo avec des avantages par rapport aux systèmes d&#39;autres modèles de simplicité et de coût.

Nous présentons ici les résultats de deux expériences distinctes. Le premier emploie GCaMP pour mesurer la réponse d&#39;un neurone sensoriel spécifique à un stimulus externe définie, ce qui donne un bon exemple de la façon dont les journalistes de calcium fluorescents peuvent être utilisés pour surveiller optiquement l&#39;activité neuronale dans intacts C. elegans. La seconde emploie cameleon pour mesurer le calcium intracellulaire transitoire déclenché dans le neurone en réponse aux dommages la...

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

Avec son petit corps, transparent et documenté neuroanatomie et une foule de techniques génétiques qui se prêtent et réactifs,<em&gt; C. elegans</em&gt; Fait un organisme modèle idéal pour<em&gt; In vivo</em&gt; Imagerie neuronale utilisant relativement simples et peu coûteuses techniques. Nous décrivons ici l&#39;imagerie seul neurone dans les animaux adultes intacts génétiquement codés à l&#39;aide des indicateurs de calcium fluorescentes.

En imagerie calcique in vivo des neurones en 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.

In vivo laser axotomie en C. elegans

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

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Neurosciences

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.

Réponses d&#39;imagerie neuronale dans les préparations d&#39;organe voméronasal Slice Exprimant un capteur de calcium codées génétiquement

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.

Quantification automatisée de la fluorescence dans Synaptic<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.

Imagerie in vivo de Dauer spécifique neuronale Rénovation en 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.

In Vivo cérébrale fonctionnelle approche d&#39;imagerie à base de calcium Bioluminescent Indicateur GFP-aequorine

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.

En utilisant une puce olfactif microfluidique adapté pour l’imagerie de l’activité neuronale en réponse aux phéromones dans les neurones de tête mâle C. Elegans

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.

Imagerie biphotonique Calcium en Dendrites neuronales dans des tranches de cerveau

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;

Imagerie ratiométrique Calcium des neurones individuels en comportement 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.

En imagerie calcique Vivo des cellules ciliées ligne latérale chez le poisson zèbre larvaire

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.