Siamo grati al Dott. Karl-Heinz Krause e Vincent Jaquet per aiuto e consiglio per impostare questi protocolli, e ringraziamo anche Christoph Bauer e Jérôme Bosset dalla piattaforma Bioimmagini del PRN e il Dr. Navin Gopaldass per il loro supporto tecnico. La ricerca è supportata da una sovvenzione ProDoc della National Science Foundation svizzero.

1. Visualizzazione e misurazione qualitativa del ROS Produzione in fagosomi Le perle OBG-rivestite devono essere preparati in anticipo. Le procedure di rivestimento perline e la tecnica di sovrapposizione agar sono adattati dai riferimenti pubblicati 5,14. <ol><li> Aggiungere 1 ml di sospensione di 3,0 micron sfere di silice carbossilati (circa 1,8 x 10 9 sfere) in una provetta da 1,5 ml, lavare le perle 3x con 1 ml di PBS da giro veloce e vortex. </li><li> Risospendere le sfere in 1 ml di PBS contenente 25 mg / ml cianammide (per attivare le perle di silice carbossilati di legarsi in modo covalente prelabeled BSA), incubare su una ruota per 15 minuti. </li><li> Lavare 3x con 1 ml di tampone di accoppiamento (0,1 M borato di sodio, pH 8,0) mediante rotazione rapida (centrifugare a piena velocità in una mini centrifuga da tavolo per 5 sec oppure centrifugare a 2000 xg per 1 minuto in una centrifuga da tavolo) e vortex per rimuovere l&#39;eccesso cyanamide. </li><li> Mescolare le perline lavati con 500 ml di coupling tampone contenente 1 mg di OxyBurst Green (OBG) H2HFF (diidro-2 &#39;, 4,5,6,7,7&#39;-hexafluorofluorescein)-BSA, riempire il tubo con gas di azoto da un gas-can standard prima tappatura, e incubare su una ruota per 14 ore (una notte) a temperatura ambiente al buio. </li><li> Lavare le perline 2x con 1 ml di tampone di tempra (250 mM glicina in PBS) per rimuovere reagito OBG, e due volte con tampone di accoppiamento per rimuovere il tampone quenching dalla rotazione veloce e vortex. </li><li> Aggiungere 1 ml di tampone di accoppiamento contenenti 50 mg di Alexa Fluor 594 succinimidyl estere di coniugare al BSA. Riempire il tubo con azoto prima del livellamento, e incubare su una ruota per 1,5 ore a temperatura ambiente al buio. </li><li> Lavare le perline 3x con 1 ml di tempra buffer giro veloce e vortex per fermare la reazione, poi lavare le perle 3x con 1 ml di PBS da giro veloce e vortex. </li><li> Infine, risospendere le sfere in 1 ml di PBS con 2 ml di 10% w / v azide per conservazione a lungo termine. Misurare la concentration di perline in sospensione con un emocitometro (solitamente intorno 1-2 x 10 9 perline / ml), riempire il tubo con azoto prima del livellamento, e conservare a 4 ° C al buio. </li><li> L&#39;efficienza del rivestimento della fluoresceina OBG può essere verificata controllando lo spettro di emissione con eccitazione a 500 nm. Quando ossidato da H 2 O 2 in presenza di perossidasi di rafano (HRP), l&#39;intensità di fluorescenza di perline ossidati, al picco di emissione (538 nm), è 11-12x superiore a quella di perline rivestite nonoxidized. </li><li> Harvest esponenziale crescita delle cellule Dictyostelium da un piatto di 10 centimetri Petri, piastra diverse densità di celle su tre centimetri piatti con un materiale plastico otticamente trasparente o con fondo di vetro, e crescere durante la notte. Scegli i piatti che sono circa l&#39;80% confluenti per l&#39;esperimento. Un protocollo dettagliato per la coltivazione di cellule di Dictyostelium è stato pubblicato il 15. </li><li> Sostituire il terreno di coltura con LoFlo medio (LF), incubare per2 ore prima dell&#39;esperimento al fine di diminuire l&#39;autofluorescenza extracellulare e intraendosomal del terreno di coltura HL5C. </li><li> Parallelamente, sciogliere 10 ml 1,5% Bacto agar in mezzo LF, versare l&#39;agar su una superficie piana (cioè una lastra di vetro di 10 cm x 10 cm) in modo da formare uno strato di agar dello spessore di circa 1 mm attendere 10-15 min a solidificare. Tagliare lo strato di agar in 2 cm x 2 centimetri quadrati e posto in LF medio per un uso successivo. </li><li> Nel frattempo, preparare la filatura-disk o microscopio a campo largo, impostare la temperatura della camera ambientale a 22 ° C e regolare le impostazioni per questo esperimento. (Vedi ulteriori commenti nella discussione). </li><li> Dopo 2 ore di incubazione, aspirare il terreno LF dal piatto 3 cm, ma il monostrato cellulare dovrebbe ancora essere coperta da una pellicola sottile di supporto. Diluire le perle rivestite da 1,5 x 10 7 perline / ml e aggiungere 10 ml sullo strato di cellule. </li><li> Prendete un foglio agar quadrato, drenare i liquidi in eccesso, ma mantenere bagnato. Mettere delicatamente the agar quadrato sulla parte superiore dello strato di cellule. Non spostare la piazza agar quando è sdraiato sulle cellule. L&#39;agar molle viene utilizzato per aumentare il contatto tra le perle e cellule, migliorando così l&#39;assorbimento, ed inoltre comprime leggermente le cellule, mantenendoli meglio nel piano focale dell&#39;obiettivo. </li><li> Mettere il coperchio sul piatto, posizionarlo sul palco microscopio, e automaticamente scattare foto nei canali rosso, verde e fase ogni 1 min per 2 ore o più. </li><li> Selezionare e concentrarsi su eventi cellulari che contengono l&#39;intero processo di fagocitosi. Unire i 3 canali ottimizzati e assemblare le immagini in un filmato utilizzando software professionale di elaborazione delle immagini. Quantificare intensità di fluorescenza di ciascun perline selezionati canali rosso e verde, e il rapporto di verde / rosso rifletterà la phagosomal dinamica ROS produzione delle cellule. </li></ol> 2. Throughput medio quantitativa e misurazione dei intracellulare Superossido Produzione <ol><li> Raccogliere one 80% piatto confluenti di Dictyostelium in 10 ml di terreno HL5C. Cellule Centrifuga Dictyostelium a 850 xg per 5 minuti, con attenzione e completamente aspirare eccesso di terreno. Risospendere le cellule in tampone SS6.4 [0.12 M sorbitolo in tampone Sorensen (14,69 mM KH 2 PO 4 e 6,27 mM Na 2 HPO 4), pH 6,4], contare le celle e diluire ad una densità finale di 6 x 10 6 cellule / ml (vedi ulteriori commenti nella discussione). </li><li> Aggiungere 50 ml di sospensione cellulare in ciascun pozzetto di una non trasparente 96 pozzetti bianco (vedi ulteriori commenti nella discussione). </li><li> Diluire DHE magazzino (30 mM in DMSO) 500 volte con SS6.4, pipetta 50 ml di DHE diluito in ciascun pozzetto utilizzando una pipetta multicanale, se necessario. La concentrazione finale di DHE è di 30 micron. La reazione inizia immediatamente. </li><li> Stimoli o inibitori possono essere aggiunti a questo punto, o in altri punti temporali in funzione delle esigenze specifiche. </li><li> Utilizzare il punto &quot;top lettura &amp; # end34; modalità di un lettore di fluorescenza per micropiastre, con fluorescenza eccitazione / emissione a 522 nm nm/605, letto ogni 2 min per 1 ora, medio shake 5 sec / min, a 22 ° C. </li></ol> 3. Quantitativa e High Throughput Misura della extracellulare H 2 O 2 Produzione <ol><li> Seguire gli stessi passi descritti in 2.1 e 2.2. </li><li> Preparare HRP diluita con l&#39;aggiunta di 5 ml di HRP magazzino (100 U / ml in acqua distillata) in 10 ml di SS6.4, vortex o capovolgere la provetta per mescolare bene e tenere in ghiaccio per un uso successivo. La soluzione di HRP diluita è di 0,05 U / ml. </li><li> Preparare la miscela di reazione AUR miscelando il magazzino AUR (AUR 10 mM in DMSO) e la soluzione di HRP diluita in tampone SS6.4 alle concentrazioni finali di 6,25 mM, e 0.005 U / ml, rispettivamente. A titolo di esempio, per preparare la miscela di reazione per 40 reazioni, mescolare 1.600 ml di SS6.4 con 400 ml di HRP diluita e 2,5 ml di soluzione madre AUR. </li><li> Aggiungere 50 ml di mix AURTure in ogni pozzetto usando una pipetta multicanale, se necessario. Ora la reazione si inneschi. </li><li> Stimoli o inibitori possono essere aggiunti a questo punto, o in altri punti temporali in funzione delle esigenze specifiche. </li><li> Utilizzare il punto finale modalità &quot;lettura top&quot; di un lettore di fluorescenza piatto micro, con fluorescenza di eccitazione / emissione a 530 nm nm/590, leggere ogni 2 min per 1 ora, medio scossa 5 sec / min, a 22 ° C. </li></ol>

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Nessun conflitto di interessi dichiarati.

Rispetto ai metodi precedentemente descritti, il saggio OBG visualizza dinamicamente il processo di phagosomal generazione di ROS a livello di singola cellula, invece di misurare un segnale medio ROS da una popolazione di cellule. Tali metodi popolazione calcolo della media tendono a oscurare le informazioni critiche causate dalla fagocitosi nonsynchronous. Abbiamo adattato con successo DHE e AUR saggi di Dictyostelium e ottimizzato i protocolli. Soprattutto, abbiamo specificato i tipi e localizzazioni subcellu...

Le specie reattive dell&#39;ossigeno (ROS) sono coinvolti in una vasta gamma di processi biologici quali la difesa ospite, la segnalazione, lo sviluppo del tessuto e la risposta al danno, così come l&#39;ipertensione e il cancro. Il macchinario ossidasi phagosomal NADPH ben studiato è dedicato alla generazione di ROS rapido, conosciuto come il burst ossidativo, per uccidere i batteri ingeriti in phagosomes neutrofili &#39;1. Inoltre, la perdita di elettroni come sottoprodotto della catena respiratoria mitocondriale è stato precedentemente ritenuto responsabile solo per una fonte regolamentata di ROS. Ma di recente, è stato identificato come un importante meccanismo per contribuire all&#39;uccisione intraphagosomal dei batteri nei macrofagi del mouse 2. Negli ultimi anni, l&#39;ameba sociale, Dictyostelium, è diventata un modello potente e popolare per studiare i meccanismi cellulari intrinseche della risposta immunitaria innata. Infatti, Dictyostelium e fagociti umani condividono un sorprendentemente elevato livello di conservazione in moleculamacchinari r responsabili per i batteri rilevamento, fagocitazione e uccidendo 3,4. Gli omologhi di proteine ​​ed enzimi legati alla produzione di ROS o di detossificazione, come ossidasi NADPH, catalasi, superossido dismutasi, possono essere trovati in umano e Dictyostelium. Come l&#39;ameba più studiato, Dictyostelium presenta diversi vantaggi unici rispetto sistema modello mammiferi. Crescono a temperatura ambiente senza la necessità di CO 2, con un tempo di raddoppio di 8-10 ore. Possono essere facilmente mantenute come colture aderenti o sospensione. Inoltre, grazie alla loro genoma aploide completamente sequenziato e annotato, e alla manipolazione genetica facile, Dictyostelium è diventata una molto attraente sperimentale organismo modello. In studi precedenti, vari derivati ​​clorurati e fluorurati di fluoresceina (collettivamente noti come OxyBurst verde, OBG) che emettono fluorescenza dopo ossidazione da ROS, sono stati utilizzati come reporter ROS. Cell-permeante estDerivati ​​erified vengono utilizzati per misurare citoplasmatica ROS, che destrano-o derivati ​​cellule impermeant accoppiati a proteine ​​sono utilizzati per misurare extracellulare ROS. In particolare, perline OBG BSA-rivestite sono già stati utilizzati per rilevare phagosomal produzione di ROS in cellule di mammifero 5. Tuttavia, l&#39;approccio lettore-su micropiastra può solo dare una curva di generazione di ROS mediata da una popolazione di cellule. Con la presente protocollo base Dictyostelium, un fagocita professionale, e le condizioni sperimentali ottimizzate, otteniamo fagocitosi stabile ed efficiente senza coniugando qualsiasi opsonina sulle perline. DHE è stato utilizzato in vari sistemi modello, come neutrofili e macrofagi mammiferi, per rilevare la produzione di ROS 6-9. Nel frattempo, vi sono alcune controversie sulla specificità e sensibilità del metodo 8,10. Come una versione migliorata del Amplex Red, l&#39;intensità di fluorescenza di RUA è meno sensibile al pH, che lo rende più adatto da misurareROS in ambienti nonneutral o debolmente acide. AUR è stato recentemente applicato in diversi sistemi di mammifero 11,12, ma il suo uso in modelli non mammiferi, che spesso richiedono mezzi di crescita debolmente acido, non è stato ancora riportato. Inoltre, non esiste un protocollo pubblicato per quantitativamente e dinamicamente misurare la produzione di ROS e la localizzazione nel ameba sociale Dictyostelium. L&#39;obiettivo del set di protocolli presentato è quello di fornire una soluzione semplice e versatile per il controllo di diversi ROS e la loro localizzazione, e in seguito invia intuizioni meccanismi cellulari ROS-correlati. Per il saggio OBG, abbiamo usato la microscopia diretta a monitorare l&#39;intero processo di generazione phagosomal ROS, dopo l&#39;assorbimento di perline OBG rivestite da cellule di Dictyostelium, e fornito un nuovo approccio per studiare il meccanismo di uccisione intraphagosomal dei batteri. Abbiamo ottimizzato medio-throughput DHE e AUR saggi in Dictyostelium, per misurare superox intracellulareide extracellulare e H 2 O 2 produzione, rispettivamente, utilizzando LPS come un potente stimolatore ROS. Si noti che LPS è stato recentemente mostrato di aumentare l&#39;attività battericida del Dictyostelium verso batteri fagocitati 13. Inoltre, il trattamento con DEDTC e catalasi esplicitamente confermato che questi due metodi specificamente misurano diversi tipi e localizzazioni subcellulari di ROS in Dictyostelium. Infine, il saggio OBG può essere adattato a qualsiasi cellula fagocitica aderente per ulteriori opsonizzare le perline con ligandi per recettori di fagocitosi di cellule animali. In linea di principio, i saggi DHE e AUR può anche essere ottimizzati per misure in qualsiasi cella aderenti o non aderenti sotto appropriate condizioni sperimentali.

<table border="1">
	<tbody>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>REAGENTS</td>
		</tr>
		<tr>
			<td>OxyBURST Green H2HFF BSA</td>
			<td>Invitrogen</td>
			<td>O-13291</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa Fluor 594</td>
			<td>Invitrogen</td>
			<td>A-20004</td>
			<td></td>
		</tr>
		<tr>
			<td>Carboxylated silica beads</td>
			<td>Kisker Biotech</td>
			<td>PSi-3.0COOH</td>
			<td></td>
		</tr>
		<tr>
			<td>HL5C medium</td>
			<td>ForMedium</td>
			<td>HLC0102</td>
			<td></td>
		</tr>
		<tr>
			<td>LoFlo medium</td>
			<td>ForMedium</td>
			<td>LF1001</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto agar</td>
			<td>BD</td>
			<td>204010</td>
			<td></td>
		</tr>
		<tr>
			<td>Dihydroethidium</td>
			<td>Sigma</td>
			<td>37291-25MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Amplex UltraRed</td>
			<td>Invitrogen</td>
			<td>A36006</td>
			<td></td>
		</tr>
		<tr>
			<td>Horseradish peroxidase</td>
			<td>Roche</td>
			<td>10108090001</td>
			<td></td>
		</tr>
		<tr>
			<td>Diethyldithiocarbamate (DEDTC)</td>
			<td>Sigma</td>
			<td>D3506-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Catalase</td>
			<td>Sigma</td>
			<td>C9322-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyanamide</td>
			<td>Sigma</td>
			<td>187364-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Lipopolysaccharides</td>
			<td>Sigma</td>
			<td>L2630-25G</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>EQUIPMENT</td>
		</tr>
		<tr>
			<td>ibidi &#956;-Dish 35 mm, high</td>
			<td>ibidi</td>
			<td>81156</td>
			<td>Bottom made of optically clear plastic</td>
		</tr>
		<tr>
			<td>MatTek dish 35 mm</td>
			<td>MatTek corporation</td>
			<td>P35G-1.5-14-C</td>
			<td>Bottom made of a glass coverslip</td>
		</tr>
		<tr>
			<td>Scepter Cell Counter</td>
			<td>Merck Millipore</td>
			<td>PHCC00000</td>
			<td></td>
		</tr>
		<tr>
			<td>White 96 well plate</td>
			<td>Nunc</td>
			<td>236108</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>SORVALL</td>
			<td>Legend RT</td>
			<td></td>
		</tr>
		<tr>
			<td>Microplate reader</td>
			<td>BioTek</td>
			<td>Synergy Mx</td>
			<td></td>
		</tr>
	</tbody>
</table>

detecting, visualizing and quantitating the generation of reactive oxygen species in an amoeba model system

Le specie reattive dell&#39;ossigeno (ROS) comprendono una gamma di molecole contenenti ossigeno reattive e di breve durata, che sono interconvertiti o eliminati sia catalitica o spontaneamente in modo dinamico. A causa delle brevi durate di più ROS e la diversità delle loro fonti e localizzazioni subcellulari, un quadro completo può essere ottenuto solo da misure accurate utilizzando una combinazione di protocolli. Qui, vi presentiamo una serie di tre protocolli diversi con OxyBurst Green (OBG) rivestite perline, o dihydroethidium (DHE) e Amplex Ultrared (AUR), di monitorare qualitativamente e quantitativamente diversi ROS in fagociti professionali come Dictyostelium. Abbiamo ottimizzato le perline procedure di rivestimento e perle di OBG rivestite occasione e la microscopia diretta di visualizzare dinamicamente intraphagosomal generazione di ROS a livello di singola cellula. Abbiamo identificato lipopolisaccaride (LPS) da E. coli come stimolatore potente per la generazione di ROS in Dictyostelium. Inoltre, Dtempo reale eveloped, saggi medio-throughput utilizzando DHE e AUR per misurare quantitativamente superossido intracellulare ed extracellulare H 2 O 2 produzione, rispettivamente.

La generazione di ROS in fagosomi può essere visualizzato qualitativamente e dinamicamente mediante microscopia (S1 File). La fluorescenza rossa emessa da Alexa Fluor 594 è pH-sensibile e rimane costante nell&#39;ambiente phagosomal, mentre l&#39;ossidazione di OBG aumenta la fluorescenza nel canale verde. Gli spettri di emissione di in vitro ossidato e perline OBG rivestite nonoxidized sono confrontati in Figura 1B, mostrando un significativo aumento di intensità dopo l&#39...

Watch this Scientific Journal Video about Detecting, Visualizing and Quantitating the Generation of Reactive Oxygen Species in an Amoeba Model System at JoVE.com

Detecting, Visualizing and Quantitating the Generation of Reactive Oxygen Species in an Amoeba Model System

Abbiamo adattato una serie di protocolli per la misurazione delle specie reattive dell&#39;ossigeno (ROS) che possono essere applicate in vari modelli cellulari amebe e di mammifero per studi qualitativi e quantitativi.

Individuare, visualizzare e quantificare la generazione di specie reattive dell&#39;ossigeno in un modello di sistema di Amoeba

Reactive oxygen species (ROS) comprise a range of reactive and short-lived, oxygen-containing molecules, which are dynamically interconverted or ...

detecting-visualizing-quantitating-generation-reactive-oxygen-species

Research

JoVE Journal

Biology

16.0K Views.  University of Geneva.  Abbiamo adattato una serie di protocolli per la misurazione delle specie reattive dell'ossigeno (ROS) che possono essere applicate in vari modelli cellulari amebe e di mammifero per studi qualitativi e quantitativi. 

Video: Detecting, Visualizing and Quantitating the Generation of Reactive Oxygen Species in an Amoeba Model System

Visualizing the Beating Heart in Drosophila

The Drosophila heart has recently emerged as a good model system for examining the genetic, cellular, and molecular mechanisms underlying function in myogenic hearts. A key step in examining heart function in the fly is finding a way to access the heart in a manner that preserves its myogenic function while still allowing the beating heart organ to be observed and recorded. Two different methods for observing and recording the beating heart in both larva and adult Drosophila are described here. Our semi-intact preparation using adult flies allows clear visualization of the abdominal heart without interference from the pigmented cuticle and overlying fat bodies. To record larval heart beats it is necessary to immobilize the larva, which minimizes body wall movements thereby reducing heart movements that are not associated with myocardial contractions. Our methodologies produce stable adult and larval heart preparations that can beat for hours at rates of 1-3 Hz.

Visualizing the Beating Heart in Drosophila

Technique required for visualizing the beating heart in larval and adult Drosophila are presented. Each life stage requires a different methodology.

Visualizzare il cuore pulsante di Drosophila</em

The Drosophila heart has recently emerged as a good model system for examining the genetic, cellular, and molecular mechanisms underlying function in ...

Ricerca

Biologia

Electron Spin Resonance Micro-imaging of Live Species for Oxygen Mapping

This protocol describes an electron spin resonance (ESR) micro-imaging method for three-dimensional mapping of oxygen levels in the immediate environment of live cells with micron-scale resolution1. Oxygen is one of the most important molecules in the cycle of life. It serves as the terminal electron acceptor of oxidative phosphorylation in the mitochondria and is used in the production of reactive oxygen species. Measurements of oxygen are important for the study of mitochondrial and metabolic functions, signaling pathways, effects of various stimuli, membrane permeability, and disease differentiation. Oxygen consumption is therefore an informative marker of cellular metabolism, which is broadly applicable to various biological systems from mitochondria to cells to whole organisms. Due to its importance, many methods have been developed for the measurements of oxygen in live systems. Current attempts to provide high-resolution oxygen imaging are based mainly on optical fluorescence and phosphorescence methods that fail to provide satisfactory results as they employ probes with high photo-toxicity and low oxygen sensitivity. ESR, which measures the signal from exogenous paramagnetic probes in the sample, is known to provide very accurate measurements of oxygen concentration. In a typical case, ESR measurements map the probe's lineshape broadening and/or relaxation-time shortening that are linked directly to the local oxygen concentration. (Oxygen is paramagnetic; therefore, when colliding with the exogenous paramagnetic probe, it shortness its relaxation times.) Traditionally, these types of experiments are carried out with low resolution, millimeter-scale ESR for small animals imaging. Here we show how ESR imaging can also be carried out in the micron-scale for the examination of small live samples. ESR micro-imaging is a relatively new methodology that enables the acquisition of spatially-resolved ESR signals with a resolution approaching 1 micron at room temperature2. The main aim of this protocol-paper is to show how this new method, along with newly developed oxygen-sensitive probes, can be applied to the mapping of oxygen levels in small live samples. A spatial resolution of ~30 x 30 x 100 &mu;m is demonstrated, with near-micromolar oxygen concentration sensitivity and sub-femtomole absolute oxygen sensitivity per voxel. The use of ESR micro-imaging for oxygen mapping near cells complements the currently available techniques based on micro-electrodes or fluorescence/phosphorescence. Furthermore, with the proper paramagnetic probe, it will also be readily applicable for intracellular oxygen micro-imaging, a capability which other methods find very difficult to achieve.

This protocol describes a method for micron-scale three-dimensional imaging of oxygen concentration in the immediate environment of live cells by electron spin resonance microscopy.

Electron Spin Resonance micro-imaging delle specie dal vivo per la mappatura di ossigeno

This protocol describes an electron spin resonance (ESR) micro-imaging method for three-dimensional mapping of oxygen levels in the immediate environment ...

Do-It-Yourself Device for Recovery of Cryopreserved Samples Accidentally Dropped into Cryogenic Storage Tanks

Liquid nitrogen is colorless, odorless, extremely cold (-196 &deg;C) liquid kept under pressure. It is commonly used as a cryogenic fluid for long term storage of biological materials such as blood, cells and tissues 1,2. The cryogenic nature of liquid nitrogen, while ideal for sample preservation, can cause rapid freezing of live tissues on contact - known as 'cryogenic burn'2, which may lead to severe frostbite in persons closely involved in storage and retrieval of samples from Dewars. Additionally, as liquid nitrogen evaporates it reduces the oxygen concentration in the air and might cause asphyxia, especially in confined spaces2.
In laboratories, biological samples are often stored in cryovials or cryoboxes stacked in stainless steel racks within the Dewar tanks1. These storage racks are provided with a long shaft to prevent boxes from slipping out from the racks and into the bottom of Dewars during routine handling. All too often, however, boxes or vials with precious samples slip out and sink to the bottom of liquid nitrogen filled tank. In such cases, samples could be tediously retrieved after transferring the liquid nitrogen into a spare container or discarding it. The boxes and vials can then be relatively safely recovered from emptied Dewar. However, the cryogenic nature of liquid nitrogen and its expansion rate makes sunken sample retrieval hazardous. It is commonly recommended by Safety Offices that sample retrieval be never carried out by a single person. Another alternative is to use commercially available cool grabbers or tongs to pull out the vials3. However, limited visibility within the dark liquid filled Dewars poses a major limitation in their use.
In this article, we describe the construction of a Cryotolerant DIY retrieval device, which makes sample retrieval from Dewar containing cryogenic fluids both safe and easy.

Here we present a low cost, durable cryotolerant device for sample retrieval from Dewar tanks filled with liquid nitrogen. The ease of construction and modular design of the device makes the process of sample retrieval from cryogenic tanks safe and easy.

Do-It-Yourself dispositivo per il recupero di campioni crioconservati cadere accidentalmente nelle cisterne criogeniche

Liquid nitrogen is colorless, odorless, extremely cold (-196 &deg;C) liquid kept under pressure. It is commonly used as a cryogenic fluid for long term ...

Generation, Purification, and Characterization of Cell-invasive DISC1 Protein Species

Protein aggregation is seen as a general hallmark of chronic, degenerative brain conditions like, for example, in the neurodegenerative diseases Alzheimer's disease (A&beta;, tau), Parkinson's Disease (&alpha;-synuclein), Huntington's disease (polyglutamine, huntingtin), and others. Protein aggregation is thought to occur due to disturbed proteostasis, i.e. the imbalance between the arising and degradation of misfolded proteins. Of note, the same proteins are found aggregated in sporadic forms of these diseases that are mutant in rare variants of familial forms.
Schizophrenia is a chronic progressive brain condition that in many cases goes along with a permanent and irreversible cognitive deficit. In a candidate gene approach, we investigated whether Disrupted-in-schizophrenia 1 (DISC1), a gene cloned in a Scottish family with linkage to chronic mental disease1, 2, could be found as insoluble aggregates in the brain of sporadic cases of schizophrenia3. Using the SMRI CC, we identified in approximately 20 % of cases with CMD but not normal controls or patients with neurodegenerative diseases sarkosyl-insoluble DISC1 immunoreactivity after biochemical fractionation. Subsequent studies in vitro revealed that the aggregation propensity of DISC1 was influenced by disease-associated polymorphism S704C4, and that DISC1 aggresomes generated in vitro were cell-invasive5, similar to what had been shown for A&beta;6, tau7-9, &alpha;-synuclein10, polyglutamine11, or SOD1 aggregates12. These findings prompted us to propose that at least a subset of cases with CMD, those with aggregated DISC1 might be protein conformational disorders.
 Here we describe how we generate DISC1 aggresomes in mammalian cells, purify them on a sucrose gradient and use them for cell-invasiveness studies. Similarly, we describe how we generate an exclusively multimeric C-terminal DISC1 fragment, label and purify it for cell invasiveness studies. Using the recombinant multimers of DISC1 we achieve similar cell invasiveness as for a similarly labeled synthetic &alpha;-synuclein fragment. We also show that this fragment is taken up in vivo when stereotactically injected into the brain of recipient animals.

The generation, purification and cell invasion of intracellular, cytoplasmic full length DISC1 protein aggresomes from cell cultures and of a labeled, multimeric recombinant DISC1 protein fragment in E. coli are described. Cell invasiveness is shown for recipient cells in cell culture and for neurons in vivo after stereotactical brain inoculation.

Generazione, purificazione e caratterizzazione di specie DISC1 Cell-invasive Protein

Protein aggregation is seen as a general hallmark of chronic, degenerative brain conditions like, for example, in the neurodegenerative diseases ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

Generation of Marked and Markerless Mutants in Model Cyanobacterial Species

Cyanobacteria are ecologically important organisms and potential platforms for production of biofuels and useful industrial products. Genetic manipulation of cyanobacteria, especially model organisms such as Synechocystis sp. PCC6803 and Synechococcus sp. PCC7002, is a key tool for both basic and applied research. Generation of unmarked mutants, whereby chromosomal alterations are introduced into a strain via insertion of an antibiotic resistance cassette (a manipulatable fragment of DNA containing one or more genes), followed by subsequent removal of this cassette using a negative selectable marker, is a particularly powerful technique. Unmarked mutants can be repeatedly genetically manipulated, allowing as many alterations to be introduced into a strain as desired. In addition, the absence of genes encoding antibiotic resistance proteins in the mutated strain is desirable, as it avoids the possibility of 'escape' of antibiotic resistant organisms into the environment. However, detailed methods for repeated rounds of genetic manipulation of cyanobacteria are not well described in the scientific literature. Here we provide a comprehensive description of this technique, which we have successfully used to generate mutants with multiple deletions, single point mutations within a gene of interest and insertion of novel gene cassettes.

Introducing multiple genomic alterations into cyanobacteria is an essential tool in the development of strains for industrial and basic research purposes. We describe a system for generating unmarked mutants in the model cyanobacterial species Synechocystis sp. PCC6803 and marked mutants in Synechococcus sp. PCC7002.

Generazione di marcato e markerless Mutanti nel modello di cianobatteri Specie

Cyanobacteria are ecologically important organisms and potential platforms for production of biofuels and useful industrial products. Genetic manipulation ...

Rodent Working Heart Model for the Study of Myocardial Performance and Oxygen Consumption

Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways that cannot be accomplished in vivo. For example, inotropic medications commonly also affect preload and afterload, precluding load-independent assessments of their myocardial effects in vivo. Additionally, this model allows for sampling of coronary sinus effluent without contamination from systemic venous return, permitting assessment of myocardial oxygen consumption. Further, the advent of miniaturized pressure-volume catheters has allowed for the precise quantification of markers of both systolic and diastolic performance. We describe a model in which the left ventricle can be studied while performing both volume and pressure work under controlled conditions. 
In this technique, the heart and lungs of a Sprague-Dawley rat (weight 300-500 g) are removed en bloc under general anesthesia. The aorta is dissected free and cannulated for retrograde perfusion with oxygenated Krebs buffer. The pulmonary arteries and veins are ligated and the lungs removed from the preparation. The left atrium is then incised and cannulated using a separate venous cannula, attached to a preload block. Once this is determined to be leak-free, the left heart is loaded and retrograde perfusion stopped, creating the working heart model. The pulmonary artery is incised and cannulated for collection of coronary effluent and determination of myocardial oxygen consumption. A pressure-volume catheter is placed into the left ventricle either retrograde or through apical puncture. If desired, atrial pacing wires can be placed for more precise control of heart rate. This model allows for precise control of preload (using a left atrial pressure block), afterload (using an afterload block), heart rate (using pacing wires) and oxygen tension (using oxygen mixtures within the perfusate).

Isolated working heart models can be used to measure the effect of loading conditions, heart rate, and medications on myocardial performance and oxygen consumption. We describe methods for preparation of a rodent left heart working model that permits study of systolic and diastolic performance and oxygen consumption under various conditions.

Roditore Working Model Cuore per lo Studio della performance miocardica e consumo di ossigeno

Isolated working heart models have been used to understand the effects of loading conditions, heart rate and medications on myocardial performance in ways ...

Visualizing the Early Stages of Phagocytosis

The mammalian body is equipped with various layers of mechanisms that help to defend itself from pathogen invasions. Professional phagocytes of the immune system &#8212; such as neutrophils, dendritic cells, and macrophages &#8212; retain the innate ability to detect and clear such invading pathogens through phagocytosis1. Phagocytosis involves choreographed events of membrane reorganization and actin remodeling at the cell surface2,3. Phagocytes successfully internalize and eradicate foreign molecules only when all stages of phagocytosis are fulfilled. These steps include recognition and binding of the pathogen by pattern recognition receptors (PRRs) residing at the cell surface, formation of phagocytic cup through actin-enriched membranous protrusions (pseudopods) to surround the particulate, and scission of the phagosome followed by phagolysosome maturation that results in the killing of the pathogen3,4.
Imaging and quantification of various stages of phagocytosis is instrumental for elucidating the molecular mechanisms of this cellular process. The present manuscript reports methods to study the different phases of phagocytosis. We describe a microscope-based approach to visualize and quantify the binding, phagocytic cup formation, and the internalization of particulate by phagocytes. As phagocytosis occurs when innate receptors on phagocytic cells encounter ligands on a target particle bigger than 0.5 &#181;m, the assays we present here comprise the use of pathogenic fungi Candida albicans and other particulates such as zymosan and IgG-coated beads.

Here we describe a microscope-based technique to visualize and quantify the early cascades of events during phagocytosis of pathogens such as the fungi Candida albicans and particulates that are larger than 0.5 &#181;m including zymosan and IgG-coated beads.

Visualizzare le fasi iniziali della fagocitosi

The mammalian body is equipped with various layers of mechanisms that help to defend itself from pathogen invasions. Professional phagocytes of the immune ...

Establishment of an Extracellular Acidic pH Culture System

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the role of acidic extracellular pH in tumor aggressiveness and its underlying mechanism has not been extensively studied compared to hypoxic or nutrient starvation conditions. In addition, a well-defined culture method to mimic the acidic extracellular tumor microenvironment has not been fully reported.
Here we present a simple in vitro culture method to maintain acidic extracellular pH using reduced bicarbonate and increased lactate or HCl concentrations in the culture medium. The medium pH was sustained for at least 24 h and gradually decreased by 72 h following culture of PANC-1 and AsPC-1 pancreatic cancer cells. Three distinct acidic media conditions in this study highly upregulated pH-responsive genes such as MSMO1, INSIG1, and IDI1 compared to hypoxia or nutrient starvation. The upregulation of these genes can be used as a marker of acidic pH. These simple techniques are beneficial to elucidate underlying mechanisms of tumor malignancy under acidic tumor microenvironment. Therefore, our extracellular acidic pH culture system enables discovery of cellular acidic pH responses not only in cancer cells but also in primary cells, such as renal tubular cells, in relation to the other acidic disorders including, diabetic ketoacidosis, lactic acidosis, renal tubular acidosis, and respiratory acidosis.

The acidic tumor microenvironment plays critical roles in tumor progression. To assess the effects of acidic extracellular pH on cancer cells in vitro, we established simple acidic culture systems.

Istituzione di un pH extracellulare acido sistema cultura

Conditions of the tumor microenvironment, such as hypoxia or nutrient starvation, play critical roles in cancer progression and malignancy. However, the ...

Stimulation of Stem Cell Niches and Tissue Regeneration in Mouse Skin by Switchable Protoporphyrin IX-Dependent Photogeneration of Reactive Oxygen Species In Situ

Here, we describe a protocol to induce switchable in vivo photogeneration of endogenous reactive oxygen species (ROS) in mouse skin. This transient production of ROS in situ efficiently activates cell proliferation in stem cell niches and stimulates tissue regeneration as strongly manifested through the acceleration of burn healing and hair follicle growth processes. The protocol is based on a regulatable photodynamic treatment that treats the tissue with precursors of the endogenous photosensitizer protoporphyrin IX and further irradiates the tissue with red light under tightly controlled physicochemical parameters. Overall, this protocol constitutes an interesting experimental tool to analyze ROS biology.

The aim of this protocol is to induce transient in vivo production of nonlethal levels of reactive oxygen species (ROS) in mouse skin, further promoting physiological responses in the tissue.

Stimolazione di nicchie di cellule staminali e rigenerazione tissutale nella pelle di topo mediante fotogenerazione commutabile protoporfirina IX-dipendente di specie reattive dell'ossigeno in situ

Here, we describe a protocol to induce switchable in vivo photogeneration of endogenous reactive oxygen species (ROS) in mouse skin. This transient ...