Ringraziamo Scienze della Vita e la Facoltà di Arti e della Scienza presso l&#39;Università Queen per il finanziamento di questo lavoro. Come pure, ringraziamo il laboratorio Chin-Sang per fornire i reagenti necessari, le attrezzature e il supporto tecnico. Ringraziamo anche QGEM 2011, soprattutto Tony Lui per il suo contributo alla discussione.

1. Preparazione / lavaggio dei Worms <ol><li> Sincronizzare i vermi a giovane adulto 11. </li><li> Pipettare 2 ml di basale S su una piastra 5 cm Chemiotassi di scena vermi che hanno appena eliminato il prato di OP50 E. coli. Inclinare la piastra come necessario per garantire i vermi vengono lavati dalla superficie della piastra nel buffer. </li><li> Pipettare 1 ml della soluzione Basal verme-S in una provetta da microcentrifuga. </li><li> Centrifugare per 10 secondi utilizzando un PicoFuge a 6.600 giri al minuto. </li><li> Aspirare il basale S, lasciando il pellet di vermi indisturbati. </li><li> Aggiungere 1 ml di soluzione S basale alla provetta, capovolgere un paio di volte per lavare i vermi. </li><li> Ripetere i passaggi 1,4-1,6 altre tre volte. </li><li> Centrifugare per 10 sec una quinta volta, questa volta aspirando il supernatante in un volume finale di ca. 100 l. </li><li> Pipettare 2 ml di vermi su una piastra NGM per garantire non ci sono tra i 50 ei 250 vermi in ciascun campione 2 microlitri. Regolarela concentrazione di vermi nella basale S come richiesto da risospendere i vermi in un volume più piccolo o più grande di S basale. </li><li> Utilizzare i vermi nel test subito dopo il lavaggio i vermi per un massimo di 1 ora. </li></ol> 2. Preparazione delle piastre di prova <ol><li> Marcatura la parte inferiore di una piastra 5 cm, dividere il piatto in 4 quadranti uguali. Agar chemiotassi o NGM possono essere utilizzati. Un minimo di 3 studi sono necessari per ceppo genetico in fase di test. </li><li> Segnare un cerchio di raggio 0,5 centimetri circa l&#39;origine (Figura 1). </li><li> Segnare un punto in ogni quadrante sia con una &quot;T&quot; per &quot;Test&quot; o una &quot;C&quot; per &quot;controllo&quot;, assicurando che i siti sono equidistanti dalla provenienza e l&#39;altro. I punti devono essere di almeno 2 cm di distanza dall&#39;origine. Segna i primi quadranti a sinistra e in basso come quadranti di prova e in alto a destra e quadranti in basso a sinistra come controlli (Figura 1). </li></ol> 3. Esecuzione del test </p&gt; <ol><li> Miscelare la soluzione di prova, combinando volumi uguali del composto in esame e 0,5 M azide (un anestetico utilizzato per arrestare i vermi al raggiungimento di un quadrante). Miscelare la soluzione di controllo, combinando il solvente usato per diluire il composto in esame con 0,5 M azide. </li><li> Pipettare 2 ml di soluzione di vite senza fine (preparato in 1.8) dal pellet sulla origine (dove le due linee si intersecano). </li><li> Immediatamente dopo, pipetta 2 ml di soluzione di prova sulle due siti &quot;T&quot;. Analogamente, pipettare la stessa quantità della soluzione di controllo sui due siti &quot;C&quot;. </li><li> Una volta che i vermi e odorante gocce sono stati assorbiti in agar, sostituire i coperchi e capovolgere le piastre. </li><li> Dopo 60 minuti, mettere i vermi in un 4 ° C incubatore. Rimuovere solo una targa dal termostato quando può essere contato. Lasciando i vermi a temperatura ambiente, può consentire loro di mobilitarsi nuovamente. </li><li> Registrare il numero di vermi in ogni quadrante che ha attraversato completamente la circ interioreLe. </li><li> Ripetere i punti da 3.2 a 3.6 utilizzando la soluzione di controllo sia nel test di controllo e quadranti. Questo servirà come la piastra di controllo. Tre di tali piastre dovrebbero essere fatte e corrono per servire come un controllo appropriato. </li></ol> 4. Interpretazione dei punteggi / determinare l&#39;indice di chemiotassi <ol><li> Calcolare l&#39;indice di chemiotassi utilizzando l&#39;equazione 1. Questo produrrà un indice chemiotattica tra -1.0 e +1.0. </li></ol> (1) Chemiotassi Index = (# Worms in entrambi i quadranti di prova - # Worms in entrambi i quadranti di controllo) / (Totale # di Segnate Worms) Un punteggio di 1,0 indica attrazione massima verso il bersaglio e rappresenta il 100% dei vermi che arrivano nei quadranti contenenti il ​​bersaglio chimico. Un indice di -1.0 è la prova di repulsione massima. Metodi di analisi simili sono già stati impiegati 3 (Tabella 1). <ol start="2"><li> Segnala il Chemotaxi medias Index (CI) ed errore standard della media (SEM). Eseguire confronto T-test di Student i dati dalle piastre di prova e di controllo. </li></ol>

<ol>
	<li>Bargmann, C. I., Hartwieg, E., Horvitz, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Odorant-selective+genes+and+neurons+mediate+olfaction+in+C.+elegans.">Odorant-selective genes and neurons mediate olfaction in C. elegans.</a> Cell. 74, 515-527 (1993).</li><li>Bargmann, C. I., Horvitz, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemosensory+neurons+with+overlapping+functions+direct+chemotaxis+to+multiple+chemicals+in+C.+elegans.">Chemosensory neurons with overlapping functions direct chemotaxis to multiple chemicals in C. elegans.</a> Neuron. 7, 729-742 (1991).</li><li>Lee, J., Jee, C., McIntire, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ethanol+preference+in+C.+elegans.">Ethanol preference in C. elegans.</a> Genes Brain Behav. 8, 578-585 (2009).</li><li>Swierczek, N. A., Giles, A. C., Rankin, C. H., Kerr, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+behavioral+analysis+in+C.+elegans.">High-throughput behavioral analysis in C. elegans.</a> Nat. Methods. 8, 592-598 (2011).</li><li>Ward, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemotaxis+by+the+nematode+Caenorhabditis+elegans:+identification+of+attractants+and+analysis+of+the+response+by+use+of+mutants.">Chemotaxis by the nematode Caenorhabditis elegans: identification of attractants and analysis of the response by use of mutants.</a> Proc. Natl. Acad. Sci. U.S.A. 70, 817-821 (1973).</li><li>Colbert, H. A., 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=Odorant-specific+adaptation+pathways+generate+olfactory+plasticity+in+C.+elegans.">Odorant-specific adaptation pathways generate olfactory plasticity in C. elegans.</a> Neuron. 14, 803-812 (1995).</li><li>Kauffman, A., Parsons, L., Stein, G., Wills, A., Kaletsky, R., Murphy, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=C.+elegans+Positive+Butanone+Learning,+Short-term,+and+Long-term+Associative+Memory+Assays.">C. elegans Positive Butanone Learning, Short-term, and Long-term Associative Memory Assays.</a> J. Vis. Exp. (49), e2490 (2011).</li><li>Troemel, E. R., Kimmel, B. E., 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=Reprogramming+chemotaxis+responses:+sensory+neurons+define+olfactory+preferences+in+C.+elegans.">Reprogramming chemotaxis responses: sensory neurons define olfactory preferences in C. elegans.</a> Cell. 91, 161-169 (1997).</li><li>Pierce-Shimomura, J. T., Morse, T. M., Lockery, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fundamental+role+of+pirouettes+in+Caenorhabditis+elegans+chemotaxis.">The fundamental role of pirouettes in Caenorhabditis elegans chemotaxis.</a> J Neurosci. 19, 9557-9569 (1999).</li><li>Frokjaer-Jensen, C., Ailion, M., Lockery, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonium-acetate+is+sensed+by+gustatory+and+olfactory+neurons+in+Caenorhabditis+elegans.">Ammonium-acetate is sensed by gustatory and olfactory neurons in Caenorhabditis elegans.</a> PLoS One. 3, e2467 (2008).</li><li>Porta-de-la-Riva, M., Fontrodona, L., Villanueva, A., Cer&#243;n, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Basic+Caenorhabditis+elegans+Methods:+Synchronization+and+Observation.">Basic Caenorhabditis elegans Methods: Synchronization and Observation.</a> J. Vis. Exp. (64), e4019 (2012).</li><li>Sengupta, P., 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=Cell+fate+specification+and+differentiation+in+the+nervous+system+of+Caenorhabditis+elegans.">Cell fate specification and differentiation in the nervous system of Caenorhabditis elegans.</a> Dev. Genet. 18, 73-80 (1996).</li><li>Hart, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavior.">Behavior.</a> WormBook. , (1895).</li></ol>

Non abbiamo nulla da rivelare.

Chemiotassi, anche se controllato da un complesso insieme di meccanismi neuronali e cellulari, può essere facilmente e oggettivamente quantificato utilizzando saggi di chemiotassi. Per ottenere i migliori risultati da saggi, alcuni passaggi critici devono essere prese. In primo luogo, mettendo in scena i vermi è essenziale per produrre risultati sperimentali coerenti. Worms in diverse fasi della vita comportano in modo diverso 13; worm stage in modo misto può risultati sperimentali skew. In secondo luogo, ...

Ward primo sviluppato il saggio di chemiotassi nel 1973 5, e da allora ha avuto vasta portata delle applicazioni. Neurobiologia è un campo che ha beneficiato di utilizzare una varietà di saggi di chemiotassi. Adattamento olfattivo, una semplice forma di apprendimento e memoria, è stata dimostrata in C. elegans utilizzando saggi di chemiotassi 6. Essi sono stati utilizzati anche per dimostrare che C. elegans possono sviluppare tolleranza etanolo-un risultato che dimostra non solo la plasticità comportamentale dei vermi, ma che mostra anche che i vermi possono essere molto utile nello studio della dipendenza umana 3. I saggi sono stati anche sviluppati per dimostrare la capacità di C. elegans per memorizzare breve e memoria a lungo termine, mostrando che le associazioni sono fatte dai vermi tra fattori chemiotattici e cibo (OP50) 7. Inoltre, data la vasta informazioni attualmente disponibili per quanto riguarda la C. elegans genoma, il chemotaxis comportamento di C. elegans è stato modificato numerose volte inducendo mutazioni 1,8. Ciò consente molte possibilità ingegneria eccitanti, come lo sviluppo di C. elegans come strumento di biorisanamento. Così, dal momento che lo sviluppo iniziale del saggio chemiotassi nel 1973, è stato spesso modificato e utilizzato per spiegare i misteri in una varietà di discipline. Alcuni saggi volti alla scoperta del percorso specifico assunto dai vermi verso un bersaglio. Il saggio prototipo di questo tipo è stato sviluppato da Ward 5. Tre i vermi sono stati collocati su agar fuso per 15 min. I loro movimenti furono rilevati dalla impronta hanno lasciato mentre viaggiavano dalla periferia della piastra un gradiente fino a un attrattivo al centro della piastra. Tutti i vermi sulla piastra sono stati arrestati utilizzando cloroformio alla fine di ogni prova. Uno discendente di questo metodo collocato un singolo verme nel mezzo della piastra con l&#39;attrattiva e il controllo di unt distanze uguali e contrarie dall&#39;origine 2. Pierce-Shimomura et al. sviluppato un saggio per osservare l&#39;esatta natura del movimento coinvolti nella chemiotassi 9. Vermi individuali sono stati collocati in nove centimetri piastre di Petri o che contengono una concentrazione uniforme di una sostanza attrattiva o una sfumatura a forma radiale, che si conclude con la fonte di una sostanza attrattiva. Un programma software per computer che riconosce il verme è stata usata per registrare il comportamento osservato. Una videocamera collegata ad un microscopio lavorato in collaborazione con la fase di regolare automaticamente la piastra Petri come dosaggio corse a garantire il verme rimasto nel campo visivo. Da questo, le informazioni più dettagliate è stata scoperta per quanto riguarda la causa di piroette visualizzati da C. elegans. Altri saggi, più simile a quello descritto qui, testato la risposta di una vasta popolazione di vermi a composti di prova. Due quadranti chemiotassi test sono statiutilizzati per esplorare i ruoli che i vari neuroni, recettori e molecole di trasduzione del segnale riprodotti quando C. elegans è stato esposto a vari composti 1. Tra 20-50 vermi lavate sono state collocate vicino al centro del piatto con una attrattiva e un controllo ad estremità polari insieme con l&#39;anestetico, sodio azide (NaN 3). Dopo 60 minuti, un indice chemiotattica con valori da -1.0 a +1.0 è stata generata sulla base della differenza tra il numero di vermi venivano apposta sul attrattivo o il controllo. Un indice chemiotattica simile è stato utilizzato nel saggio riportato in questo articolo, sebbene il saggio precedenza omesso di valutare rigorosamente vermi non mobili. Questo saggio è stato poi ulteriormente applicata a testare gli effetti di ablazione neuronale sulla chemiotassi. Un&#39;altra variante del citato saggio è stato eseguito dove 100-200 vermi sono stati collocati al centro di una piastra contenente quattro quadranti 3. Quadranti adiacenti o contenevano il test ocontrollare la sostanza. Come in saggi precedenti, i vermi state immobilizzate con l&#39;azione del sodio azide prima di essere ottenuto. Un metodo simile è descritto qui come un modo per valutare la risposta di C. elegans a vari composti. Tuttavia, il metodo seguito ha il vantaggio di valutare solo i vermi che hanno superato una distanza limite che separa cellulare da vermi immobili. Altri test hanno incorporato linee guida simili per ignorare i vermi immobili. Frøkjær-Jensen et al. sviluppato un saggio versatile che può essere utilizzato per testare composti solubili sia volatili e acqua 10. Un piatto Petri è stata divisa in quattro quadranti. I quadranti superiore e inferiore non contengono solventi. Il quadrante di sinistra conteneva acqua, e il diritto di cui il attrattivo. Quando si testano odoranti volatili, l&#39;analita è stato posto sul coperchio del piatto, sulla corretta quadrante, mentre i composti solubili in acqua sono stati posizionati direttamente sul agar. I metodi attualmente esistenti per valutare la risposta chemiotattica di C. elegans sono costantemente in fase di perfezionamento per ottimizzare la loro facilità d&#39;uso, efficienza e precisione. Così, mentre il saggio descritto qui ha la capacità di valutare il maggior numero di vermi (massimo throughput:. 250 vermi / ora per piastra, leggermente maggiore della velocità dimostrata da Lee et al 3); la vera forza di questo metodo è l&#39; succinta culmine di molti degli attributi di test precedenti (Tabella 1).

<table border="1">
 <tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalogue Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>S Basal (- cholesterol) [5.8 g NaCl; 1 M K phosphate buffer, pH 6.0; dH2O to 1 liter.] Autoclave</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>PicoFuge</td>
 <td>Stratagene</td>
 <td>400552</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Microscopes</td>
 <td>Leica</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Dissecting</td>
 <td>Leica</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>P1000 Pipette</td>
 <td>Gilson</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>P10 Pipette</td>
 <td>Gilson</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>0.5 M Sodium Azide</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Chemotaxis Agar [1.6% BBL-agar (Benton-Dickinson) or 2% Difco-agar. Autoclave. Add 5 mM potassium phosphate, pH 6.0; 1 mM CaCl2, 1 mM MgSO4]</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Ethanol/Distilled Water</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Test Compounds (eg. 0.5% diacetyl)</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Agar</td>
 <td>Bio-Rad</td>
 <td>166-0600</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>NH4Cl</td>
 <td>Amresco</td>
 <td>CA97062-046</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>MOPS</td>
 <td>VWR</td>
 <td>CA12001-120</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>NH4OH</td>
 <td>BDH</td>
 <td>CABDH8641-2</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>0.25% Tween 20</td>
 <td>Bio-Rad</td>
 <td>170-6531</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>

c. elegans chemotaxis assay

Molti organismi utilizzare chemiotassi a cercare fonti di cibo, evitare sostanze nocive, e trovare compagni. Caenorhabditis elegans è impressionante comportamento chemiotassi. La premessa dietro testare la risposta dei vermi a un odorizzante è quello di metterli in una zona e osservare il movimento evocata in risposta a un odorizzante. Anche con i molti saggi disponibili, ottimizzando verme partendo posizione rispetto sia al controllo e aree di test, minimizzando l&#39;interazione di vermi con l&#39;altro, pur mantenendo dimensioni significative campione rimane un lavoro in corso 1-10. Il metodo qui descritto mira a risolvere questi problemi modificando il saggio sviluppato da Bargmann et al. 1. Una capsula di Petri è diviso in quattro quadranti, due quadranti opposti contrassegnati &quot;Test&quot; e due sono designati &quot;Control&quot;. Anestetico viene posto in tutti i test e siti di controllo. I vermi sono collocati nel centro del piatto con un circle segnato attorno all&#39;origine per garantire che i vermi non mobili saranno ignorati. Utilizzando un sistema a quattro quadranti piuttosto che uno o due 2 1 elimina polarizzazione nel movimento dei vermi, come sono equidistanti dai campioni di prova e di controllo, indipendentemente da quale lato della provenienza cominciarono. Questo aggira il problema di vermi essere costretti a viaggiare attraverso un cluster di altri worm per rispondere a un odorizzante, che può ritardare vermi o costringerli a prendere un percorso più tortuoso, ottenendo una interpretazione non corretta del loro percorso previsto. Questo metodo presenta anche vantaggi pratici da avere un campione più ampio e che consente al ricercatore di eseguire il test incustodito e segnare i vermi una volta che il tempo a disposizione è scaduto.

Confrontando wild-type (N2) C. elegans alla ODR-10 (KY10) mutante. Abbiamo usato diacetile, un noto C. elegans chemiotattico, confrontare vermi tipo selvatico a quello di un mutante che manca il recettore per diacetile 1,12. Per tipo selvatico (N2) vermi l&#39;indice chemiotattico era 0.100 ± 0.066 per l&#39;etanolo, e 0,839 ± 0,031-0,5% diacetile. Come previsto, diacetile provoca una risposta chemoattractive significativo da worm wild-type (p &l...

Watch this Scientific Journal Video about C. elegans Chemotaxis Assay at JoVE.com

C. elegans Chemotaxis Assay

Un metodo di valutazione quantitativa della risposta chemiotattica dei<em&gt; Caenorhabditis elegans</em&gt; È descritto. Un indice chemiotattico (CI) è stato impiegato come un modo per valutare con precisione la risposta dei vermi a determinati obiettivi, e servire da piattaforma di confronto tra i ceppi e composti di interesse.

C. elegans Chemiotassi Assay

Many organisms use chemotaxis to seek out food sources, avoid noxious substances, and find mates.  Caenorhabditis elegans has impressive chemotaxis ...

Research

JoVE Journal

Biology

C. elegans Chemotaxis Assay

45.0K Views.  Queen's University. Un metodo di valutazione quantitativa della risposta chemiotattica dei Caenorhabditis elegans È descritto. Un indice chemiotattico (CI) è stato impiegato come un modo per valutare con precisione la risposta dei vermi a determinati obiettivi, e servire da piattaforma di confronto tra i ceppi e composti di interesse.

Video: C. elegans Chemotaxis Assay

Generation of Stable Transgenic C. elegans Using Microinjection

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1. The plasmid DNA rearranges to form extrachromosomal concatamers that are stably inherited, though not with the same efficiency as actual chromosomes 2. A gene of interest is co-injected with an obvious phenotypic marker, such as rol-6 or GFP, to allow selection of transgenic animals under a dissecting microscope. The exogenous gene may be expressed from its native promoter for cellular localization studies. Alternatively, the transgene can be driven by a different tissue-specific promoter to assess the role of the gene product in that particular cell or tissue. This technique efficiently drives gene expression in all tissues of C. elegans except for the germline or early embryo 3. Creation of transgenic animals is widely utilized for a range of experimental paradigms. This video demonstrates the microinjection procedure to generate transgenic worms. Furthermore, selection and maintenance of stable transgenic C. elegans lines is described.

This video demonstrates the technique of microinjection into the gonad of C. elegans to create transgenic animals.

Generazione di Stabile transgenici C. elegans Utilizzando Microiniezione

Transgenic Caenorhabditis elegans can be readily created via microinjection of a DNA plasmid solution into the gonad 1.  The plasmid DNA rearranges to ...

Ricerca

Biologia

Application of a C. elegans Dopamine Neuron Degeneration Assay for the Validation of Potential Parkinson's Disease Genes

Improvements to the diagnosis and treatment of Parkinson's disease (PD) are dependent upon knowledge about susceptibility factors that render populations at risk. In the process of attempting to identify novel genetic factors associated with PD, scientists have generated many lists of candidate genes, polymorphisms, and proteins that represent important advances, but these leads remain mechanistically undefined. Our work is aimed toward significantly narrowing such lists by exploiting the advantages of a simple animal model system. While humans have billions of neurons, the microscopic roundworm Caenorhabditis elegans has precisely 302, of which only eight produce dopamine (DA) in hemaphrodites. Expression of a human gene encoding the PD-associated protein, alpha-synuclein, in C. elegans DA neurons results in dosage and age-dependent neurodegeneration.
Worms expressing human alpha-synuclein in DA neurons are isogenic and express both GFP and human alpha-synuclein under the DA transporter promoter (Pdat-1). The presence of GFP serves as a readily visualized marker for following DA neurodegeneration in these animals. We initially demonstrated that alpha-synuclein-induced DA neurodegeneration could be rescued in these animals by torsinA, a protein with molecular chaperone activity 1. Further, candidate PD-related genes identified in our lab via large-scale RNAi screening efforts using an alpha-synuclein misfolding assay were then over-expressed in C. elegans DA neurons. We determined that five of seven genes tested represented significant candidate modulators of PD as they rescued alpha-synuclein-induced DA neurodegeneration 2. Additionally, the Lindquist Lab (this issue of JoVE) has performed yeast screens whereby alpha-synuclein-dependent toxicity is used as a readout for genes that can enhance or suppress cytotoxicity. We subsequently examined the yeast candidate genes in our C. elegans alpha-synuclein-induced neurodegeneration assay and successfully validated many of these targets 3, 4.
Our methodology involves generation of a C. elegans DA neuron-specific expression vector using recombinational cloning of candidate gene cDNAs under control of the Pdat-1 promoter. These plasmids are then microinjected in wild-type (N2) worms, along with a selectable marker for successful transformation. Multiple stable transgenic lines producing the candidate protein in DA neurons are obtained and then independently crossed into the alpha-synuclein degenerative strain and assessed for neurodegeneration, at both the animal and individual neuron level, over the course of aging.

Application of a C. elegans Dopamine Neuron Degeneration Assay for the Validation of Potential Parkinson&#039;s Disease Genes

This video demonstrates how to use C. elegans to assess dopaminergic neuron neurodegeneration as a model for Parkinson's disease. Furthermore, genetic screens are used to identify factors that either enhance degeneration or are neuroprotective.

L&#39;applicazione di una degenerazione C. elegans Dopamina Saggio Neuron per la convalida dei potenziali morbo di Parkinson geni

Improvements to the diagnosis and treatment of Parkinson's disease (PD) are dependent upon knowledge about susceptibility factors that render populations ...

Paradigms for Pharmacological Characterization of C. elegans Synaptic Transmission Mutants

The nematode, Caenorhabditis elegans, has become an expedient model for studying neurotransmission. C. elegans is unique among animal models, as the anatomy and connectivity of its nervous system has been determined from electron micrographs and refined by pharmacological assays. In this video, we describe how two complementary neural stimulants, an acetylcholinesterase inhibitor, called aldicarb, and a gamma-aminobutyric acid (GABA) receptor antagonist, called pentylenetetrazole (PTZ), may be employed to specifically characterize signaling at C. elegans neuromuscular junctions (NMJs) and facilitate our understanding of antagonistic neural circuits.
Of 302 C. elegans neurons, nineteen GABAergic D-type motor neurons innervate body wall muscles (BWMs), while four GABAergic neurons, called RMEs, innervate head muscles. Conversely, thirty-nine motor neurons express the excitatory neurotransmitter, acetylcholine (ACh), and antagonize GABA transmission at BWMs to coordinate locomotion. The antagonistic nature of GABAergic and cholinergic motor neurons at body wall NMJs was initially determined by laser ablation and later buttressed by aldicarb exposure. Acute aldicarb exposure results in a time-course or dose-responsive paralysis in wild-type worms. Yet, loss of excitatory ACh transmission confers resistance to aldicarb, as less ACh accumulates at worm NMJs, leading to less stimulation of BWMs. Resistance to aldicarb may be observed with ACh-specific or general synaptic function mutants. Consistent with antagonistic GABA and ACh transmission, loss of GABA transmission, or a failure to negatively regulate ACh release, confers hypersensitivity to aldicarb. Although aldicarb exposure has led to the isolation of numerous worm homologs of neurotransmission genes, aldicarb exposure alone cannot efficiently determine prevailing roles for genes and pathways in specific C. elegans motor neurons. For this purpose, we have introduced a complementary experimental approach, which uses PTZ.
Neurotransmission mutants display clear phenotypes, distinct from aldicarb-induced paralysis, in response to PTZ. Wild-type worms, as well as mutants with specific inabilities to release or receive ACh, do not show apparent sensitivity to PTZ. However, GABA mutants, as well as general synaptic function mutants, display anterior convulsions in a time-course or dose-responsive manner. Mutants that cannot negatively regulate general neurotransmitter release and, thus, secrete excessive amounts of ACh onto BWMs, become paralyzed on PTZ. The PTZ-induced phenotypes of discrete mutant classes indicate that a complementary approach with aldicarb and PTZ exposure paradigms in C. elegans may accelerate our understanding of neurotransmission. Moreover, videos demonstrating how we perform pharmacological assays should establish consistent methods for C. elegans research.

This video demonstrates how to employ two neural stimulants, aldicarb and pentylenetetrazole (PTZ), in complementary ways to study synaptic function in the nematode, C. elegans. This complementary approach may also be used to shed light on evolutionarily conserved mechanisms for modulating neuronal synchrony and has implications for epilepsy and seizures.

Paradigmi per la caratterizzazione farmacologica di C. elegans Mutanti trasmissione sinaptica

The nematode, Caenorhabditis elegans, has become an expedient model for studying neurotransmission. C. elegans is unique among animal models, as the ...

Dissecting and Recording from The C. Elegans Neuromuscular Junction

Neurotransmission is the process by which neurons transfer information via chemical signals to their post-synaptic targets, on a rapid time scale. This complex process requires the coordinated activity of many pre- and post-synaptic proteins to ensure appropriate synaptic connectivity, conduction of electrical signals, targeting and priming of secretory vesicles, calcium sensing, vesicle fusion, localization and function of postsynaptic receptors and finally, recycling mechanisms. As neuroscientists it is our goal to elucidate which proteins function in each of these steps and understand their mechanisms of action. Electrophysiological recordings from synapses provide a quantifiable read out of the underlying electrical events that occur during synaptic transmission. By combining this technique with the powerful array of molecular and genetic tools available to manipulate synaptic proteins in C. elegans, we can analyze the resulting functional changes in synaptic transmission. 
The C. elegans NMJs formed between motor neurons and body wall muscles control locomotion, therefore, mutants with uncoordinated locomotory phenotypes (known as unc s) often perturb synaptic transmission at these synapses 1. Since unc mutants are maintained on a rich supply of a bacterial food source, they remain viable as long as they retain some pharyngeal pumping ability to ingest food. This, together with the fact that C. elegans exist as hermaphrodites, allows them to pass on mutant progeny without the need for elaborate mating behaviors. These attributes, coupled with our recent ability to record from the worms NMJs 2,3,7 make this an excellent model organism in which to address precisely how unc mutants impact neurotransmission. 
The dissection method involves immobilizing adult worms using a cyanoacrylic glue in order to make an incision in the worm cuticle exposing the NMJs. Since C. elegans adults are only 1 mm in length the dissection is performed with the use of a dissecting microscope and requires excellent hand-eye coordination. NMJ recordings are made by whole-cell voltage clamping individual body wall muscle cells and neurotransmitter release can be evoked using a variety of stimulation protocols including electrical stimulation, light-activated channel-rhodopsin-mediated depolarization 4 and hyperosmotic saline, all of which will be briefly described.

Application of electrophysiology to accessible synapses provides a quantifiable measure of synaptic activity, useful in analyzing synaptic mutants. This article describes a dissection method used to expose the neuromuscular junctions (NMJ) of Caenorhabditis elegans (C. elegans) and briefly discusses some of the uses to which this preparation can be applied.

Dissezione e registrazione dal bivio C. Elegans neuromuscolare

Neurotransmission is the process by which neurons transfer information via chemical signals to their post-synaptic targets, on a rapid time scale.   This ...

Generation of Transgenic C. elegans by Biolistic Transformation

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Generation of Transgenic C. elegans by Biolistic Transformation

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

Generazione di transgenici C. elegans Di Trasformazione Biolistic

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid ...

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated tools and resources for studies in this system are facilitating continued discovery of genes with more subtle phenotypes or roles. 
Here we present a generalized protocol we adapted for identifying C. elegans genes with postembryonic phenotypes of interest using RNAi2. This procedure is easily modified to assay the phenotype of choice, whether by light or fluorescence optics on a dissecting or compound microscope. This screening protocol capitalizes on the physical assets of the organism and molecular tools the C. elegans research community has produced. As an example, we demonstrate the use of an integrated transgene that expresses a fluorescent product in an RNAi screen to identify genes required for the normal localization of this product in late stage larvae and adults. First, we used a commercially available genomic RNAi library with full-length cDNA inserts. This library facilitates the rapid identification of multiple candidates by RNAi reduction of the candidate gene product. Second, we generated an integrated transgene that expresses our fluorecently tagged protein of interest in an RNAi-sensitive background. Third, by exposing hatched animals to RNAi, this screen permits identification of gene products that have a vital embryonic role that would otherwise mask a post-embryonic role in regulating the protein of interest. Lastly, this screen uses a compound microscope equipped for single cell resolution.

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

We describe a sensitized method to identify postembryonic regulators of protein expression and localization in C. elegans using an RNAi-based genomic screen and an integrated transgene that expresses a functional, fluorescently tagged protein.

RNAi di screening per identificare fenotipi postembrionale in C. elegans</em

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated ...

Basic Caenorhabditis elegans Methods: Synchronization and Observation

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has since been used extensively as a model organism 1. C. elegans possesses key attributes such as simplicity, transparency and short life cycle that have made it a suitable experimental system for fundamental biological studies for many years 2. Discoveries in this nematode have broad implications because many cellular and molecular processes that control animal development are evolutionary conserved 3.
C. elegans life cycle goes through an embryonic stage and four larval stages before animals reach adulthood. Development can take 2 to 4 days depending on the temperature. In each of the stages several characteristic traits can be observed. The knowledge of its complete cell lineage 4,5 together with the deep annotation of its genome turn this nematode into a great model in fields as diverse as the neurobiology 6, aging 7,8, stem cell biology 9 and germ line biology 10. 
An additional feature that makes C. elegans an attractive model to work with is the possibility of obtaining populations of worms synchronized at a specific stage through a relatively easy protocol. The ease of maintaining and propagating this nematode added to the possibility of synchronization provide a powerful tool to obtain large amounts of worms, which can be used for a wide variety of small or high-throughput experiments such as RNAi screens, microarrays, massive sequencing, immunoblot or in situ hybridization, among others. 
Because of its transparency, C. elegans structures can be distinguished under the microscope using Differential Interference Contrast microscopy, also known as Nomarski microscopy. The use of a fluorescent DNA binder, DAPI (4',6-diamidino-2-phenylindole), for instance, can lead to the specific identification and localization of individual cells, as well as subcellular structures/defects associated to them.

Basic Caenorhabditis elegans Methods: Synchronization and Observation

The easiness of maintaining and propagating the nematode C. elegans make it a nice model organism to work with. The possibility of synchronizing worms allows the work with a significant amount of subjects at the same developmental stage, what facilitates the study of one particular process in many animals.

Di base<em&gt; Caenorhabditis elegans</em&gt; Metodi: sincronizzazione e di osservazione

Research into the molecular and developmental biology of the nematode Caenorhabditis elegans was begun in the early seventies by Sydney Brenner and it has ...

A Method for Culturing Embryonic C. elegans Cells

C. elegans is a powerful model system, in which genetic and molecular techniques are easily applicable. Until recently though, techniques that require direct access to cells and isolation of specific cell types, could not be applied in C. elegans. This limitation was due to the fact that tissues are confined within a pressurized cuticle which is not easily digested by treatment with enzymes and/or detergents. Based on early pioneer work by Laird Bloom, Christensen and colleagues 1 developed a robust method for culturing C. elegans embryonic cells in large scale. Eggs are isolated from gravid adults by treatment with bleach/NaOH and subsequently treated with chitinase to remove the eggshells. Embryonic cells are then dissociated by manual pipetting and plated onto substrate-covered glass in serum-enriched media. Within 24 hr of isolation cells begin to differentiate by changing morphology and by expressing cell specific markers. C. elegans cells cultured using this method survive for up 2 weeks in vitro and have been used for electrophysiological, immunochemical, and imaging analyses as well as they have been sorted and used for microarray profiling.

A Method for Culturing Embryonic C. elegans Cells

We describe here a revised protocol for large-scale culture of embryonic C. elegans cells. Embryonic C. elegans cells cultured in vitro using this method, appear to differentiate and recapitulate the expression of genes in a cell specific manner. Techniques that require direct access to the cells or isolation of specific cell types from the other tissues can be applied on C. elegans cultured cells.

Un metodo per la coltura embrionale<em&gt; C. elegans</em&gt; Celle

C. elegans is a powerful model system, in which genetic and molecular techniques are easily applicable. Until recently though, techniques that require ...

Antibody Staining in C. Elegans Using &quot;Freeze-Cracking&quot;

To stain C. elegans with antibodies, the relatively impermeable cuticle must be bypassed by chemical or mechanical methods. "Freeze-cracking" is one method used to physically pull the cuticle from nematodes by compressing nematodes between two adherent slides, freezing them, and pulling the slides apart. Freeze-cracking provides a simple and rapid way to gain access to the tissues without chemical treatment and can be used with a variety of fixatives. However, it leads to the loss of many of the specimens and the required compression mechanically distorts the sample. Practice is required to maximize recovery of samples with good morphology. Freeze-cracking can be optimized for specific fixation conditions, recovery of samples, or low non-specific staining, but not for all parameters at once. For antibodies that require very hard fixation conditions and tolerate the chemical treatments needed to chemically permeabilize the cuticle, treatment of intact nematodes in solution may be preferred. If the antibody requires a lighter fix or if the optimum fixation conditions are unknown, freeze-cracking provides a very useful way to rapidly assay the antibody and can yield specific subcellular and cellular localization information for the antigen of interest.

Antibody Staining in C. Elegans Using &quot;Freeze-Cracking&quot;

"Freeze-cracking," a method for exposing the inner tissues of the nematode C. elegans to antibodies for protein localization, is demonstrated.

Antibody colorazione in<em&gt; C. Elegans</em&gt; Uso di &quot;Freeze-Cracking&quot;

To stain C.  elegans with antibodies, the relatively impermeable cuticle must be  bypassed by chemical or mechanical methods.  "Freeze-cracking" is one ...

Measuring the Effects of Bacteria on C. Elegans Behavior Using an Egg Retention Assay

C. elegans egg-laying behavior is affected by environmental cues such as osmolarity1 and vibration2. In the total absence of food C. elegans also cease egg-laying and retain fertilized eggs in their uterus3. However, the effect of different sources of food, especially pathogenic bacteria and particularly Enterococcus faecalis, on egg-laying
	behavior is not well characterized. The egg-in-worm (EIW) assay is a useful tool to quantify the effects of different types of bacteria, in this case E. faecalis, on egg- laying behavior.
	
	EIW assays involve counting the number of eggs retained in the uterus of C. elegans4. The EIW assay involves bleaching staged, gravid adult C. elegans to remove the cuticle and separate the retained eggs from the animal. Prior to bleaching, worms are exposed to bacteria (or any type of environmental cue) for a fixed period of time. After bleaching, one is very easily able to count the number of eggs retained inside the uterus of the worms. In this assay, a quantifiable increase in egg retention after E. faecalis exposure can be easily measured. The EIW assay is a behavioral assay that may be used to screen for potentially pathogenic bacteria or the presence of environmental toxins. In addition, the EIW assay may be a tool to screen for drugs that affect neurotransmitter signaling since egg-laying behavior is modulated by neurotransmitters such as serotonin and acetylcholine5-9.

Measuring the Effects of Bacteria on C. Elegans Behavior Using an Egg Retention Assay

An egg-in-worm (EIW) assay is a useful method to quantify egg-laying behavior. Alterations in egg laying can be a behavioral response of the model organism Caenorhabditis elegans to potentially harmful environmental substances such as those produced by pathogenic bacteria.

Misurare gli effetti dei batteri su<em&gt; C. Elegans</em&gt; Comportamento utilizzando un saggio di ritenzione dell&#39;uovo

C. elegans egg-laying behavior is  affected by environmental cues such as osmolarity1 and  vibration2. In the total absence of food C. elegans also cease ...