Siamo grati al dottor Stephen Robinson e la Sig.ra Hania Czerwinska (Monash University) per la generosa offerta di culture astrociti.

1. Determinare ascorbato intracellulare in cellule in coltura <ol><li> Coltura cellulare e la raccolta <ol><li> Grow sospensione (ad esempio eritroleucemia umana, K562) o cellule aderenti (ad esempio astrociti primari) utilizzando le procedure standard di coltura 19-21,32,38. Nota: per garantire le cellule contengono acido ascorbico, caricare cellule in coltura con l&#39;ascorbato sia come ascorbato o DHA 33,39. </li></ol></li><li> Creare un estratto cellulare-ascorbato contenente <ol><li> Incubare un numero adeguato di PBS sospensione (PBS)-lavati o cellule aderenti con 450 ml di ghiacciata cellulare Permeabilization Buffer [CPB; 0,1% (w / v) in PBS saponina; 4 ° C]. Nota: determinare il numero di cellule necessario per ottenere un valore di assorbanza nell&#39;intervallo lineare del test (vedi sotto) empiricamente l&#39;utente finale. Nota: estratti di tessuto possono anche essere utilizzati (vedi la discussione per ulteriori dettagli). </li><li> Agitazionecellule te in ghiaccio per 10 minuti al fine di garantire lisi cellulare approfondita. </li><li> Creare un estratto intracellulare-ascorbato contenente chiarito rimuovendo detriti cellulari mediante centrifugazione del lisato grezzo a 16.000 xg per 5 minuti in una microcentrifuga refrigerata (4 ° C). </li><li> Rimuovere accuratamente 4 x aliquote di 100 microlitri di ciascun campione e aggiungere a una sequenza orizzontale di pozzetti in una piastra a 96 pozzetti fondo piatto che contiene sia 25 pl / pozzetto di PBS (&quot;-AO&quot;) solo o 25 ml / pozzetto di 45,5 U / ml soluzione stock di L-ascorbato ossidasi (AO) in PBS (&quot;+ AO&quot;). Nota: questo dovrebbe essere fatto in parallelo con la preparazione degli standard (vedi sotto). </li></ol></li><li> L&#39;ascorbato costruzione standard-curva (deve essere costruito di nuovo per ogni test) <ol><li> Preparare una soluzione stock di 10 mM acido ascorbico in PBS freddo. Nota: Controllare la concentrazione di ascorbato spettrofotometricamente utilizzando una cuvetta di quarzo con un 1cm percorso di lunghezza a 265 nm (coefficiente di estinzione = 14.5 mM -1 cm -1) 40. </li><li> Preparare con cura una serie di standard ascorbato tra 0 e 20 micron. </li><li> In parallelo con il punto 1.2.4, rimuovere con cautela 4 × aliquote da 100 microlitri da ogni standard e aggiungere a una sequenza orizzontale di pozzetti in una piastra di fondo 96 pozzetti flat che contiene 25 ml / pozzetto di PBS (&quot;-AO&quot;) o un soluzione madre 45,5 U / ml di AO in PBS (&quot;+ AO&quot;). Nota: 100 ml di norme di ascorbato di cui sopra conterrà 0-2 nmole di ascorbato. Si prega di notare, lo scopo della AO è quello di controllare il contributo di riducenti non ascorbato di ferricianuro di riduzione. </li></ol></li><li> Determinare ascorbato intracellulare - Fase 1: rimuovere selettivamente ascorbato e quantitativamente ossidare ascorbato con ferricianuro <ol><li> Orbitally mescolare la piastra a 96 pozzetti a 550 rpm a temperatura ambiente per 5 minuti al buio coprendo la piastra in alluminio. Nota: Til suo passo dovrebbe ossidare tutti ascorbato nei pozzi &quot;+ AO&quot; al DHA. I pozzi &quot;-AO&quot; dovrebbero essere influenzate. </li><li> Aggiungere 50 ml di ferricianuro di potassio 3,5 mm (in appresso denominate &quot;ferricianuro&quot;) in PBS a tutti i pozzetti. La finale [ferricianuro] = 1 mm. Nota: Utilizzare un multipipettor. </li><li> Orbitally mescolare la piastra a 550 rpm a temperatura ambiente per altri 5 minuti al buio. Nota: Questo passo dovrebbe comportare la riduzione di ferricianuro di Ferrocianuro da ascorbato in un rapporto stechiometrico di 2 molecole di ferricianuro ridotti per 1 molecola di ascorbato ossidato. </li><li> Immediatamente aggiungere 25 ml di una soluzione recente costruzione contenente 50% (v / v) di acido acetico e 30% (w / v) di acido tricloroacetico (TCA). Nota: Utilizzare un multipipettor. </li></ol></li><li> Determinare ascorbato intracellulare - Fase 2: quantificare la quantità di ferrocianuro formato 37 <ol><li> Aggiungere 100 ml di soluzione di determinazione ferrocianuro di 37 each bene. Nota: Una soluzione di lavoro deve essere effettuata immediatamente prima dell&#39;uso: 2 ml di 3 M Na-acetato (pH 6.0); 0,5 ml di acido acetico glaciale (~ 17.4 M di acido acetico); 2 ml di 0,2 M di acido citrico; 2 ml di 3,3 FeCl mm 3 a 0,1 M di acido acetico; 1 ml di 30 mM ferene-S. Il volume finale di questa soluzione di lavoro dovrebbe essere di 7,5 ml. </li><li> Orbitally mescolare la piastra al buio a 550 rpm per 30 min a temperatura ambiente. </li><li> Leggere i valori di assorbanza dei pozzetti a 593 nm (cioè il massimo assorbimento del Fe (II) (Ferene-S) 3 complesso). </li><li> Calcolare la quantità di acido ascorbico intracellulare come nmoli di ascorbato per milione di cellule sottraendo inizialmente i valori A 593 nm per pozzi &#39;+ AO&#39; dai corrispondenti - pozzi &#39;AO&#39; per ogni campione e poi interpolazione dalla curva standard ascorbato (vedi punto 1.3 ). Quando la costruzione della curva standard, tracciare questa &quot;differenza di valore&quot; per ogni standard contro l&#39;importo di ascorbmangiato per pozzetto. </li></ol></li></ol> 2. Determinazione della ascorbato-efflusso da cellule in coltura <ol><li> Coltura cellulare e la raccolta <ol><li> Crescere sospensione o cellule aderenti come sopra (vedi punto 1.1). Nota: effettuare il saggio di seguito in un formato piattaforma 24 pozzetti con sospensione e cellule aderenti per i migliori risultati. </li><li> Risospendere le cellule in sospensione, o sovrapporre cellule aderenti, con 400 ml di pre-riscaldato soluzione salina tamponata con HEPES, con o senza calcio e magnesio, e contenente 5 mM D-glucosio (HBS / D; pH 7.3, 37 ° C) in pozzetti di una piastra da 24 pozzetti. Aggiungere lo stesso volume di HBS / D per pozzetti esenti cella specificata di ciascun piastra da 24 pozzetti da esaminare. Nota: quest&#39;ultimo servirà come controlli privi di cellule per la reazione di base (vedi sotto). </li></ol></li></ol> 3. Determinano la quantità di ascorbato Rilasciato <ol><li> Le seguenti soluzioni madre devono essere preparate in anticipo: 120U / ml AO in HBS / D (preparare fresco); 2.4 mM Ferene-S in HBS / D; 120 micron FeCl 3 e 600 mM Na-citrato in HBS / D (preparare immediatamente da soluzioni stock più concentrate). </li><li> Per avviare la reazione ferrireduction (volume finale per bene dovrebbe essere di 600 ml), aggiungere i seguenti volumi di reagenti ai singoli pozzetti già contenenti 400 ml di HBS / D: <ol><li> Aggiungere 50 ml di AO (120 U / ml) o HBS / D per accoppiato pozzetti in triplicato. La concentrazione finale AO dovrebbe essere di 10 U / ml. Nota: Label accoppiato pozzi come &quot;- AO&quot; e &quot;+ AO&quot;. </li><li> Mescolare le piastre con miscelazione delicata orbitale per 5 min a 37 ° C. </li><li> Aggiungere 50 ml di 2,4 mm ferene-S in tutti i pozzetti. La concentrazione finale ferene-S dovrebbe essere di 200 micron. Mescolare le piastre come sopra per 5 min a 37 ° C. </li><li> Aggiungere 50 ml di preparato fresco da 120 micron citrato ferrico. Il ferro finale e le concentrazioni di citrato dovrebbe essere di 10 micron di ferro e 50 micron citrato. Mescolare bene. </li></ol&gt; </li><li> In tre pozzetti di controllo triplicato, aspirare il terreno sovrastante e aggiungere 600 microlitri HBS / D contenente 0,1% di saponina. Nota: Questi risultati serviranno come &quot;cell-lisi 100%&quot; controlli di lattato deidrogenasi (LDH) rilascio da condurre in parallelo (vedi sotto). </li><li> Incubare per 60 minuti al buio a 37 ° C. </li><li> Al termine del dosaggio ascorbato-efflusso, rapidamente aspirare 500 microlitri da ogni pozzetto e aggiungere al opportunamente etichettati pozzetti in una piastra da 24 pozzetti. Nota: per cellule in sospensione, inizialmente rimuovere le cellule per centrifugazione a 4 ° C. </li><li> Aggiungere 300 microlitri aliquote di surnatante in una piastra a 96 pozzetti e poi leggere a 593 nm. </li></ol> 4. Determinazione di ascorbato extracellulare <ol><li> Leggere i valori di assorbanza dei pozzetti a 593 nm. </li><li> Calcolare la quantità di ascorbato extracellulare come nmoli ascorbato per mg di proteina (o per milione di cellule) come descritto per la determinazione di ascorbato intracellularenel passaggio 1.5.4. Nota: l&#39;utente finale deve ottimizzare le condizioni in modo che il rilascio ascorbato non è limitato dalla ascorbato intracellulare. </li></ol> 5. Determinazione della LDH uscita <ol><li> Con i restanti 200 ml di soluzione extracellulare da ciascun campione condurre un saggio di rilascio di LDH 32,41 per determinare l&#39;entità della lisi cellulare. Nota: il calcolo in% del totale LDH rilasciabile. Determinare LDH rilasciabile dai campioni che sono stati trattati con 0,1% di saponina. </li></ol>

<ol>
	<li>Buettner, G. R., Schafer, F. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Albert+Szent-Gy&#246;rgyi:+vitamin+C+identification.">Albert Szent-Gy&#246;rgyi: vitamin C identification.</a> Biochem. J. , (2006).</li><li>Padayatty, S. J., Levine, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+insights+into+the+physiology+and+pharmacology+of+vitamin.">New insights into the physiology and pharmacology of vitamin.</a> C. Can. Med. Assoc. J. 164, 353-355 (2001).</li><li>Flashman, E., Davies, S. L., Yeoh, K. K., Schofield, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Investigating+the+dependence+of+the+hypoxia-inducible+factor+hydroxylases+(factor+inhibiting+HIF+and+prolyl+hydroxylase+domain+2)+on+ascorbate+and+other+reducing+agents.">Investigating the dependence of the hypoxia-inducible factor hydroxylases (factor inhibiting HIF and prolyl hydroxylase domain 2) on ascorbate and other reducing agents.</a> Biochem. J. 427, 135-142 (2010).</li><li>Manning, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vitamin+C+Promotes+Maturation+of+T-Cells.">Vitamin C Promotes Maturation of T-Cells.</a> Antioxid. Redox Signal. 19, 2054-2067 (2013).</li><li>Asard, H., et al., Banerjee, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Redox Biochemistry. , 22-37 (2007).</li><li>Aguirre, R., May, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+in+the+vascular+bed:+Importance+of+vitamin.">Inflammation in the vascular bed: Importance of vitamin.</a> C. Pharmacol. Ther. 119, 96-103 (2008).</li><li>May, J. M., Qu, Z. -. c., Mendiratta, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protection+and+recycling+of+a-tocopherol+in+human+erythrocytes+by+intracellular+ascorbic+acid.">Protection and recycling of a-tocopherol in human erythrocytes by intracellular ascorbic acid.</a> Arch. Biochem. Biophys. 349, 281-289 (1998).</li><li>Chatterjee, I. B., Majumder, A. K., Nandi, B. K., Subramanian, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+some+major+functions+of+vitamin+C+in+animals.">Synthesis and some major functions of vitamin C in animals.</a> Ann. N. Y. Acad. Sci. 258, 24-47 (1975).</li><li>Rumsey, S. C., Levine, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Absorption+transport+and+disposition+of+ascorbic+acid+in+humans.">Absorption transport and disposition of ascorbic acid in humans.</a> J. Nutr. Biochem. 9, 116-130 (1998).</li><li>Nishikimi, M., Fukuyama, R., Minoshima, S., Shimizu, N., Yagi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cloning+and+chromosomal+mapping+of+the+human+nonfunctional+gene+for+L-gulono-g-lactone+oxidase,+the+enzyme+for+L-ascorbic+acid+biosynthesis+missing+in+man.">Cloning and chromosomal mapping of the human nonfunctional gene for L-gulono-g-lactone oxidase, the enzyme for L-ascorbic acid biosynthesis missing in man.</a> J. Biol. Chem. 269, 13685-13688 (1994).</li><li>Challem, J. J., Taylor, E. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retroviruses,+ascorbate,+mutations,+in+the+evolution+of+Homo+sapiens.">Retroviruses, ascorbate, mutations, in the evolution of Homo sapiens.</a> Free Radic. Biol. Med. 25, 130-132 (1998).</li><li>Nishikimi, M., Yagi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+basis+for+the+deficiency+in+humans+of+gulonolactone+oxidase,+a+key+enzyme+for+ascorbic+acid+biosynthesis.">Molecular basis for the deficiency in humans of gulonolactone oxidase, a key enzyme for ascorbic acid biosynthesis.</a> Am. J. Clin. Nutr. 54, 12038-12088 (1991).</li><li>Linster, C. L., Biosynthesis Van Schaftingen, E. V. i. t. a. m. i. n. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=recycling+and+degradation+in+mammals.">recycling and degradation in mammals.</a> FEBS J. 274, 1-22 (2007).</li><li>May, J. M., Qu, Z. -. c., Qiao, H., Koury, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maturational+loss+of+the+vitamin+C+transporter+in+erythrocytes.">Maturational loss of the vitamin C transporter in erythrocytes.</a> Biochem. Biophys. Res. Commun. 360, 295-298 (2007).</li><li>Wilson, J. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+vitamin+C+transport.">Regulation of vitamin C transport.</a> Annu. Rev. Nutr. 25, 105-125 (2005).</li><li>Buettner, G. 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+pecking+order+of+free+radicals+and+antioxidants:+lipid+peroxidation,+a-tocopherol,+and+ascorbate.">The pecking order of free radicals and antioxidants: lipid peroxidation, a-tocopherol, and ascorbate.</a> Arch. Biochem. Biophys. 300, 535-543 (1993).</li><li>May, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Is+ascorbic+acid+an+antioxidant+for+the+plasma+membrane.">Is ascorbic acid an antioxidant for the plasma membrane.</a> FASEB J. 13, 995-1006 (1999).</li><li>Atanassova, B. D., Tzatchev, K. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbic+acid+-+important+for+iron+metabolism.">Ascorbic acid - important for iron metabolism.</a> Folia Med. (Plovdiv). 50, 11-16 (2008).</li><li>Lane, D. J. R., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-transferrin+iron+reduction+and+uptake+are+regulated+by+transmembrane+ascorbate+cycling+in+K562+cells).">Non-transferrin iron reduction and uptake are regulated by transmembrane ascorbate cycling in K562 cells).</a> J. Biol. Chem. 283, 12701-12708 (2008).</li><li>Lane, D. J. R., Robinson, S. R., Czerwinska, H., Bishop, G. M., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two+routes+of+iron+accumulation+in+astrocytes:+ascorbate-dependent+ferrous+iron+uptake+via+the+divalent+metal+transporter+(DMT1)+plus+an+independent+route+for+ferric+iron.">Two routes of iron accumulation in astrocytes: ascorbate-dependent ferrous iron uptake via the divalent metal transporter (DMT1) plus an independent route for ferric iron.</a> Biochem. J. 432, 123-132 (2010).</li><li>Lane, D. J. R., Chikhani, S., Richardson, V., Richardson, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transferrin+iron+uptake+is+stimulated+by+ascorbate+via+an+intracellular+reductive+mechanism.">Transferrin iron uptake is stimulated by ascorbate via an intracellular reductive mechanism.</a> Biochim. Biophys. Acta. 1833, 1527-1541 (2013).</li><li>Lawen, A., Lane, D. J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammalian+iron+homeostasis+in+health+and+disease:+uptake,+storage,+transport,+and+molecular+mechanisms+of+action.">Mammalian iron homeostasis in health and disease: uptake, storage, transport, and molecular mechanisms of action.</a> Antioxid. Redox Signal. 18, 2473-2507 (2013).</li><li>Gr&#252;newald, 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=Ascorbic+acid+in+the+brain.">Ascorbic acid in the brain.</a> Brain Res. Brain Res. Rev. 18, 123-133 (1993).</li><li>Harrison, F. E., May, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vitamin+C+function+in+the+brain:+vital+role+of+the+ascorbate+transporter+SVCT2.">Vitamin C function in the brain: vital role of the ascorbate transporter SVCT2.</a> Free Radic. Biol. Med. 46, 719-730 (2009).</li><li>Rebec, G. V., Pierce, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+vitamin+as+neuromodulator:+ascorbate+release+into+the+extracellular+fluid+of+the+brain+regulates+dopaminergic+and+glutamatergic+transmission.">A vitamin as neuromodulator: ascorbate release into the extracellular fluid of the brain regulates dopaminergic and glutamatergic transmission.</a> Prog. Neurobiol. 43, 537-565 (1994).</li><li>Hediger, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+view+at+C.">New view at C.</a> Nat. Med. 8, 445-446 (2002).</li><li>Du, J., Cullen, J. J., Buettner, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbic+acid:+Chemistry,+biology+and+the+treatment+of+cancer.">Ascorbic acid: Chemistry, biology and the treatment of cancer.</a> Biochim. Biophys. Acta. 1826, 443-457 (2012).</li><li>Wilson, J. X., Peters, C. E., Sitar, S. M., Daoust, P., Gelb, A. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutamate+stimulates+ascorbate+transport+by+astrocytes.">Glutamate stimulates ascorbate transport by astrocytes.</a> Brain Res. 858, 61-66 (2000).</li><li>Danbolt, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutamate+uptake.">Glutamate uptake.</a> Prog. Neurobiol. 65, 1-105 (2001).</li><li>May, J. M., Li, L., Hayslett, K., Qu, Z. -. c. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbate+transport+and+recycling+by+SH-SY5Y+neuroblastoma+cells:+response+to+glutamate+toxicity.">Ascorbate transport and recycling by SH-SY5Y neuroblastoma cells: response to glutamate toxicity.</a> Neurochem. Res. 31, 785-794 (2006).</li><li>Rice, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbate+regulation+and+its+neuroprotective+role+in+the+brain.">Ascorbate regulation and its neuroprotective role in the brain.</a> Trends Neurosci. 23, 209-216 (2000).</li><li>Lane, D. J. R., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+glutamate+aspartate+transporter+(GLAST)+mediates+L-glutamate-stimulated+ascorbate-release+via+swelling-activated+anion+channels+in+cultured+neonatal+rodent+astrocytes.">The glutamate aspartate transporter (GLAST) mediates L-glutamate-stimulated ascorbate-release via swelling-activated anion channels in cultured neonatal rodent astrocytes.</a> Cell. Biochem. Biophys. 65, 107-119 (2012).</li><li>Lane, D. J. R., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbate+and+plasma+membrane+electron+transport+-+enzymes+vs+efflux.">Ascorbate and plasma membrane electron transport - enzymes vs efflux.</a> Free Radic. Biol. Med. 47, 485-495 (2009).</li><li>Davies, A. R. L., Belsey, M. J., Kozlowski, R. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Volume-sensitive+organic+osmolyte/anion+channels+in+cancer:+novel+approaches+to+studying+channel+modulation+employing+proteomics+technologies.">Volume-sensitive organic osmolyte/anion channels in cancer: novel approaches to studying channel modulation employing proteomics technologies.</a> Ann. N.Y. Acad. Sci. 1028, 38-55 (2004).</li><li>Novakova, L., Solich, P., Solichova, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HPLC+methods+for+simultaneous+determination+of+ascorbic+and+dehydroascorbic+acids.">HPLC methods for simultaneous determination of ascorbic and dehydroascorbic acids.</a> Trends Anal. Chem. 27, 942-958 (2008).</li><li>Vislisel, J. M., Schafer, F. Q., Buettner, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+and+sensitive+assay+for+ascorbate+using+a+plate+reader.">A simple and sensitive assay for ascorbate using a plate reader.</a> Anal. Biochem. 365, 31-39 (2007).</li><li>Lane, D. J. R., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+highly+sensitive+colorimetric+microplate+ferrocyanide+assay+applied+to+ascorbate-stimulated+transplasma+membrane+ferricyanide+reduction+and+mitochondrial+succinate+oxidation.">A highly sensitive colorimetric microplate ferrocyanide assay applied to ascorbate-stimulated transplasma membrane ferricyanide reduction and mitochondrial succinate oxidation.</a> Anal. Biochem. 373, 287-295 (2008).</li><li>Lane, D. J. R., Robinson, S. R., Czerwinska, H., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+Na+/H++exchangers+and+intracellular+pH+in+regulating+vitamin+C-driven+electron+transport+across+the+plasma+membrane.">A role for Na+/H+ exchangers and intracellular pH in regulating vitamin C-driven electron transport across the plasma membrane.</a> Biochem. J. 428, 191-200 (2010).</li><li>Corti, A., Casini, A. F., Pompella, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+pathways+for+transport+and+efflux+of+ascorbate+and+dehydroascorbate.">Cellular pathways for transport and efflux of ascorbate and dehydroascorbate.</a> Arch. Biochem. Biophys. 500, 107-115 (2010).</li><li>Laroff, G. P., Fessenden, R. W., Schuler, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+electron+spin+resonance+spectra+of+radical+intermediates+in+the+oxidation+of+ascorbic+acid+and+related+substances.">The electron spin resonance spectra of radical intermediates in the oxidation of ascorbic acid and related substances.</a> J. Am. Chem. Soc. 94, 9062-9073 (1972).</li><li>Dringen, R., Kussmaul, L., Hamprecht, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detoxification+of+exogenous+hydrogen+peroxide+and+organic+hydroperoxides+by+cultured+astroglial+cells+assessed+by+microtiter+plate+assay.">Detoxification of exogenous hydrogen peroxide and organic hydroperoxides by cultured astroglial cells assessed by microtiter plate assay.</a> Brain Res. Brain Res. Protoc. 2, 223-228 (1998).</li><li>Lane, D. J. R., Lawen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplasma+membrane+electron+transport+comes+in+two+flavors.">Transplasma membrane electron transport comes in two flavors.</a> Biofactors. 34, 191-200 (2009).</li><li>Lin, S., Lin, D. C., Flanagan, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specificity+of+the+effects+of+cytochalasin+B+on+transport+and+motile+processes.">Specificity of the effects of cytochalasin B on transport and motile processes.</a> Proc. Natl. Acad. Sci. USA. 75, 329-333 (1978).</li><li>May, J. M., Qu, Z. C., Juliao, S., Cobb, C. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ascorbic+acid+decreases+oxidant+stress+in+endothelial+cells+caused+by+the+nitroxide+tempol.">Ascorbic acid decreases oxidant stress in endothelial cells caused by the nitroxide tempol.</a> Free Radic. Res. 39, 195-202 (2005).</li><li>Avron, M., Shavit, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+sensitive+and+simple+method+for+determination+of+ferrocyanide.">A sensitive and simple method for determination of ferrocyanide.</a> Anal. Biochem. 6, 549-554 (1963).</li></ol>

Gli autori hanno nulla da rivelare.

In questo articolo presentiamo due test colorimetrici micropiastre rapidi, specifici e relativamente sensibili per la determinazione di ascorbato derivato dai compartimenti intra ed extracellulari nelle cellule in coltura. Le analisi possono essere completate con accesso alla normale attrezzatura da laboratorio e reagenti. Il reagente solo moderatamente costosa necessaria per il dosaggio è AO, che è essenziale in quanto conferisce un elevato grado di specificità analita verso L-ascorbato.</spa...

La scoperta della natura chimica di acido ascorbico (vitamina C), e la sua identificazione come il tanto ricercato &quot;fattore anti-scorbutico&quot;, di Albert Szent-Györgyi e altri in articoli pubblicati 1928-1934 1 sono stati eventi significativi nella storia di biochimica. Infatti, queste scoperte hanno contribuito a Szent-Györgyi stato assegnato il Premio Nobel per la Fisiologia e Medicina nel 1937. La suite in continua espansione dei ruoli per ascorbato di animali e fisiologia vegetale, così come la salute umana, continuano ad essere i soggetti di attivi scientifica indagini e polemiche. L-ascorbato è un abbondante riducente fisiologico e enzima cofattore nei mammiferi, e contribuisce a numerose reazioni enzimatiche ben definiti che coinvolgono il collagene idrossilazione, carnitina e noradrenalina biosintesi, metabolismo della tirosina e ormone peptidico amidazione 2. Curiosamente, Evide di montaggioSNO suggerisce che ascorbato svolge un ruolo nello stimolare altri diossigenasi ferro-dipendenti, come prolina e asparaginyl idrossilasi coinvolti nella idrossilazione e mira dei fattori inducibili (HIF) 1α e 2α 3. Un recente rapporto suggerisce che l&#39;ascorbato svolge un ruolo nella maturazione delle cellule T attraverso colpisce cromatina demetilazione attraverso la sua attività nello stimolare i idrossilasi nucleari, Jumonji C (JmjC) proteine ​​dominio; l&#39;ultimo dei quali sembrano richiedere ascorbato di piena attività 4. Infatti, la stimolazione di tali enzimi da ascorbato sembra verificarsi con un meccanismo simile alla stimolazione da ascorbato delle HIF e collagene idrossilasi. Tra gli altri effetti classici, ascorbato contribuisce significativamente antiossidazione cellulare come una catena-rottura radical scavenger idrosolubile 5 e al riciclo di membrana plasmatica α-tocoferolo (vitamina E) attraverso la riduzione della α-tocopheroxyl radicale 6, which è importante nella protezione contro la perossidazione dei lipidi di membrana 7. È importante sottolineare che, sebbene la maggior parte dei mammiferi sono in grado di sintesi de novo epatica di ascorbato da D-glucosio, primati superiori, cavie e alcuni pipistrelli dipendono da fonti alimentari di vitamina 8. Ciò è dovuto alla inattivazione del gene Gulo, gli ortologhi di cui nei mammiferi affetti codificano l&#39;enzima, γ-gulono-lattone ossidasi 9-13. Questo enzima è necessario per la reazione finale in ascorbato biosintesi di glucosio 13. Dopo l&#39;assorbimento trasportatore mediata dal lume intestinale nell&#39;uomo, ascorbato è distribuito in tutto il corpo attraverso il sistema circolatorio. La vitamina si trova in genere nella sua forma ridotta a millimolari concentrazione intracellulare (con la notevole eccezione di eritrociti in cui le concentrazioni sono in genere simili a concentrazione plasmatica prevalente), e al conc micromolarentrations (ad esempio 50-200 micron) nella maggior parte dei fluidi extracellulari 14,15. In condizioni fisiologiche, ascorbato subisce generalmente reversibile un elettrone ossidazione al ascorbil radicale libero (AFR, noto anche come monodehydroascorbate o semidehydroascorbate). Mentre l&#39;AFR è relativamente stabile radicale 16, in assenza della sua rapida riduzione enzimatica di un elettrone ritorna ascorbato, due AFR può ulteriormente dismutate una ascorbato e una deidroascorbato (DHA) 9,13,17. Entro l&#39;interno della cellula, l&#39;ossidazione del prodotto a due elettroni di ascorbato, DHA, può essere rapidamente ridotta ritorna ascorbato da glutatione-e NAD (P) H enzimatico-dipendente e reazioni non enzimatiche 13. Mentre è classicamente accettato che solo il ruolo significativo di ascorbato nel metabolismo del ferro è di stimolare l&#39;assorbimento alimentare di ferro non-eme 18, noi ed altri abbiamo fornito prove strongly suggerendo che ascorbato gioca un ruolo notevolmente ampliato nel metabolismo di questo metallo. Primo, ascorbato che viene rilasciato da cellule ascorbato-piene sembra giocare un ruolo importante nel modulare l&#39;assorbimento di ferro non legato alla transferrina dalle cellule 19,20, e molto recenti evidenze indicano che l&#39;ascorbato modula anche l&#39;assorbimento di ferro legato alla transferrina da celle 21, l&#39;ultima delle quali corrisponde ad una maggiore fisiologica percorso ferro-uptake 22. L&#39;ascorbato è essenziale per la normale funzione del sistema nervoso centrale dei mammiferi 23,24. Insieme con la corteccia surrenale, ghiandola pituitaria, il timo, retina e corpo luteo, il cervello contiene alte concentrazioni di ascorbato rispetto ad altri tessuti del corpo 23,25-27. Inoltre, l&#39;esposizione di entrambi 28,29 astrociti e cellule simili ai neuroni 30 al glutammato è noto per innescare il rilascio di ascorbato nello spazio extracellulare, dove il ascorbate è pensato per aiutare a proteggere i neuroni contro glutammato indotta da disfunzione neuronale 31. Sebbene l&#39;esatto meccanismo di glutammato indotto ascorbato di liberazione dagli astrociti è sconosciuto, di recente abbiamo fornito prove che indicano il coinvolgimento di cellule gonfiore causato da glutammato assorbimento da parte del glutammato astrociti e aspartato trasportatore (GLAST, noto anche aminoacido eccitatorio trasportatore isoforma 1 [EAAT1 ] nell&#39;uomo) e conseguente attivazione di osmolyte e anionici canali di volume sensibile (VSOACs) che sono permeabili alle piccole anioni organici come ascorbato 32. Le identità molecolari dei condotti membrana plasmatica coinvolti nella formazione VSOAC restano da identificare 33,34. Sebbene molti saggi sono stati sviluppati per la determinazione di ascorbato in campioni biologici, che comprendono spettrofotometriche, cromatografiche fluorimetrica e saggi 35,36, c&#39;è molto variabilità specificità, sensibilità, interference da contaminanti chimici, range lineare efficace e stabilità dell&#39;analita endpoint. Inoltre, altri fattori importanti che influenzano la scelta del saggio sono rapidità, facilità d&#39;uso e l&#39;accesso alle apparecchiature relativamente specializzata come una cromatografia liquida ad alta prestazione (HPLC) apparecchi. Presentiamo qui un saggio colorimetrico per micropiastre semplice e altamente specifico per la determinazione di ascorbato intracellulare in cellule in coltura, così come un test separato per la determinazione di ascorbato-efflusso da cellule coltivate. Il secondo test ha lo scopo di aggirare il problema della sottovalutazione del rilascio ascorbato dalle cellule a causa del rapido re-uptake di ascorbato rilasciato da trasportatori ascorbato di sodio-dipendente (SVCTs). Sebbene entrambi questi metodi sono apparsi in alcune delle nostre precedenti pubblicazioni 19,20,32,37,38, questo manoscritto fornisce un insieme esplicito di istruzioni e linee guida per la loro esecuzione effettiva.

<table border="0" cellpadding="0" cellspacing="0" width="678">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="60">
			<td height="60" style="height:60px;width:284px;">Nunc 96-well flat-bottom plates</td>
			<td style="width:135px;">Thermo</td>
			<td style="width:127px;">269620</td>
			<td style="width:132px;">Any flat-bottom 96-well plate can be used</td>
		</tr>
		<tr height="140">
			<td height="140" style="height:140px;width:284px;">Refrigerated benchtop microcentrifuge</td>
			<td style="width:135px;">Eppendorf&#160;</td>
			<td style="width:127px;">5415D</td>
			<td style="width:132px;">A non-refrigerated microcentrifuge that has been equilibrated to temperature in a cold room can also be used</td>
		</tr>
		<tr height="73">
			<td height="73" style="height:74px;width:284px;">Refrigerated bench-top centrifuge</td>
			<td style="width:135px;">Eppendorf&#160;</td>
			<td style="width:127px;">5810R</td>
			<td style="width:132px;">Swing-bucket</td>
		</tr>
		<tr height="260">
			<td height="260" style="height:260px;width:284px;">Bio-Rad Benchmark Plus Microplate Spectrophotometer</td>
			<td style="width:135px;">Bio-Rad</td>
			<td style="width:127px;"></td>
			<td style="width:132px;">Any microplate spectrophotometer capable of reading at 593 nm can be used and is recommended. If a filter-based plate reader is used, choose the closest wavelength possible and use the standard-curve method.</td>
		</tr>
		<tr height="120">
			<td height="120" style="height:120px;width:284px;">Ependorf MixMate (microplate orbital mixer)</td>
			<td style="width:135px;">Eppendorf&#160;</td>
			<td style="width:127px;"></td>
			<td style="width:132px;">This is a very versatile and reliable microplate mixer and works very well for these assays</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">General-purpose buffers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">Phosphate-buffered saline (PBS), pH 7.4</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="43">
			<td height="43" style="height:43px;width:284px;">MOPS-buffered saline (MBS); 137 mM NaCl, 2.7 mM KCl, 15 mM MOPS-Na+, pH 7.3</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">MBS + 5 mM D-glucose (MBS/D)</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="87">
			<td height="87" style="height:87px;width:284px;">HEPES-buffered saline + 5 mM D-glucose (HBS/D); 137 mM NaCl, 5.2 mM KCl, 1.8 mM CaCl2&#8226;2 H2O, 0.8 mM MgSO4&#8226;7 H2O, 5 mM D-glucose, 20 mM HEPES-Na+, pH 7.3)</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:284px;">Cell permeabilisation buffer (CPB; 0.1% saponin in PBS)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">General chemicals</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:284px;">L-ascorbic acid or sodium L-ascorbate</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;"></td>
			<td style="width:132px;">Highest purity preparations should be obtained</td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:284px;">Dehydro-L-ascorbic acid (DHA) dimer</td>
			<td>Sigma-Aldrich</td>
			<td>30790</td>
			<td style="width:132px;">Aqueous solutions theoretically yield 2 moles of DHA monomer per mole of DHA dimer</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;width:284px;">Cytochalasin B</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;">C6762</td>
			<td style="width:132px;">Stock solutions prepared in DMSO or ethanol</td>
		</tr>
		<tr height="100">
			<td height="100" style="height:100px;width:284px;">Ascorbate oxidase (AO)</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;">A0157</td>
			<td style="width:132px;">Stock solutions (120 U/ml) can be prepared in PBS or MBS and then frozen in aliquots</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">Potassium ferricyanide (FIC)</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;">455989</td>
			<td style="width:132px;">Trihydrate</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:284px;">Ferene-S (3-(2-Pyridyl)-5,6-di(2-furyl)-1,2,4-triazine-5&#8242;,5&#8242;&#8242;-disulfonic acid disodium salt)</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;">92940</td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">Sodium L-glutamate</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">L-glutamine</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:284px;">Saponin</td>
			<td style="width:135px;">Sigma-Aldrich</td>
			<td style="width:127px;">47036</td>
			<td style="width:132px;">Prepare a 0.1% stock solution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;"></td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:284px;">Stock solutions for intracellular ascorbate determination assay</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">3 M sodium acetate (pH 6.0)</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">Glacial acetic acid</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">0.2 M citric acid</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:284px;">3.3 mM FeCl3 in 0.1 M acetic acid</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">30 mM ferene-S</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:284px;">50% (v/v) acetic acid + 30% (w/v) trichloroacetic acid (TCA)</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;"></td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Stock solutions for ascorbate-efflux assay</td>
			<td style="width:135px;"></td>
			<td style="width:127px;"></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">AO (120 U/ml)</td>
			<td></td>
			<td></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">2.4 mM ferene-S</td>
			<td></td>
			<td></td>
			<td style="width:132px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:284px;">0.12 mM FeCl3 in 0.6 mM sodium-citrate</td>
			<td></td>
			<td></td>
			<td style="width:132px;"></td>
		</tr>
	</tbody>
</table>

a rapid and specific microplate assay for the determination of intra- and extracellular ascorbate in cultured cells

Vitamina C (acido ascorbico) svolge numerosi ruoli importanti nel metabolismo cellulare, molti dei quali sono venuti alla luce solo negli ultimi anni. Ad esempio, all&#39;interno del cervello, ascorbato agisce in maniera neuroprotettivo e neuromodulatori che coinvolge l&#39;ascorbato bicicletta tra i neuroni e astrociti vicinali - un rapporto che sembra essere cruciale per l&#39;ascorbato cervello omeostasi. Inoltre, prove emergenti suggeriscono fortemente che l&#39;ascorbato ha un ruolo notevolmente ampliato nella regolazione del metabolismo del ferro cellulare e sistemica di quanto è riconosciuto in stile classico. La crescente riconoscimento del ruolo fondamentale di ascorbato di fisiologia cellulare e organismal normale e deregolamentato richiede una serie di media-throughput e alta sensibilità tecniche analitiche che possono essere eseguiti senza la necessità di attrezzature specialistiche altamente costosi. Qui forniamo istruzioni esplicite per un mezzo di throughput, specifico e relativamente poco costoso test micropiastra per la determinazione dei both ascorbato intra ed extracellulare nelle cellule in coltura.

Determinazione del ascorbato intracellulare in cellule in sospensione coltivate Nel primo test (Figura 1), ascorbato intracellulare viene determinata, seguendo ascorbato-specifica (cioè AO-sensitive) riduzione del ferricianuro di Ferrocianuro, utilizzando la determinazione altamente sensibile di ferrocianuro da una procedura pubblicata 37. Il rilevamento di ascorbato si basa sulla chelazione colorimetrica del ferro ferroso che viene generato dalla riduzione...

Watch this Scientific Journal Video about A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells at JoVE.com

A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells

L&#39;ascorbato interpreta numerosi ruoli importanti nel metabolismo cellulare, molti dei quali sono venuti alla luce solo negli ultimi anni. Qui si descrive un medium-throughput specifico e poco costoso saggio micropiastra per la determinazione di entrambi ascorbato intra ed extracellulare in coltura cellulare.

Una rapida e specifica Microplate Assay per la determinazione di ascorbato intra-ed extracellulare in cellule in coltura

Vitamin C (ascorbate) plays numerous important roles in cellular metabolism, many of which have only come to light in recent years. For instance, within ...

a-rapid-specific-microplate-assay-for-determination-intra

Research

JoVE Journal

Biology

13.4K Views.  University of Sydney.  L'ascorbato interpreta numerosi ruoli importanti nel metabolismo cellulare, molti dei quali sono venuti alla luce solo negli ultimi anni. Qui si descrive un medium-throughput specifico e poco costoso saggio micropiastra per la determinazione di entrambi ascorbato intra ed extracellulare in coltura cellulare. 

Video: A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells

Counting and Determining the Viability of Cultured Cells

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. A hemacytometer is a thick glass slide with a central area designed as a counting chamber. Cell suspension is applied to a defined area and counted so cell density can be calculated. 

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. In this video, we demonstrate how cells are counted using a hemacytometer.

Conteggio e determinazione della vitalità delle cellule in coltura

Determining the number of cells in culture is important in standardization of culture conditions and in performing accurate quantitation experiments. A ...

Ricerca

Biologia

Clonogenic Assay: Adherent Cells

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture1. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811)2. Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant formulation.

The applicability of the clonogenic assay for evaluating reproductive viability has been established for more than 50 years. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cells.

Clonogenica saggio: cellule aderenti

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 19561. ...

Isolation and Functional Analysis of Mitochondria from Cultured Cells and Mouse Tissue

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of cell heath due to their role in both cell metabolism and energy production as well as control of apoptosis. Therefore, direct evaluation of isolated mitochondria and mitochondrial perturbation offers the ability to determine if organelle-specific (dys)function is occurring. The methods described in this protocol include isolation of intact, functional mitochondria from HEK cultured cells and mouse liver and spinal cord, but can be easily adapted for use with other cultured cells or animal tissues. Mitochondrial function assessed by TMRE and the use of common mitochondrial uncouplers and inhibitors in conjunction with a fluorescent plate reader allow this protocol not only to be versatile and accessible to most research laboratories, but also offers high throughput.

Comparison of mitochondrial membrane potential between samples yields valuable information about cellular status. Detailed steps for isolating mitochondria and assessing response to inhibitors and uncouplers using fluorescence are described. The method and utility of this protocol are illustrated by use of a cell culture and animal model of cellular stress.

Isolamento e analisi funzionale dei mitocondri da cellule in coltura e Tissue mouse

Comparison between two or more distinct groups, such as healthy vs. disease, is necessary to determine cellular status. Mitochondria are at the nexus of ...

Detection of Intracellular Gene Expression in Live Cells of Murine, Human and Porcine Origin Using Fluorescence-labeled Nanoparticles

The reprogramming of somatic cells to induced pluripotent stem cells (iPS) has successfully been performed in different mammalian species including mouse, rat, human, pig and others. The verification of iPS clones mainly relies on the detection of the endogenous expression of different pluripotency genes. These genes mostly represent transcription factors which are located in the cell nucleus. Traditionally, the proof of their endogenous expression is supplied by immunohistochemical staining after fixation of the cells. This approach requires replicate cultures of each clone at this early stage to preserve validated clones for further experiments. The present protocol describes an approach with gene-specific nanoparticles which allows the evaluation of intracellular gene expression directly in live cells by fluorescence. The nanoparticles consist of a central gold particle coupled to a capture strand carrying a sequence complementary to the target mRNA as well as a quenched reporter strand. These nanoparticles are actively endocytosed and the target mRNA displaces the reporter strand which then start to fluoresce. Therefore, specific target gene expression can be detected directly under the microscope. In addition, the emitted fluorescence allows the identification, isolation and enrichment of cells expressing a specific gene by flow cytometry. This method can be applied directly to live cells in culture without any manipulation of the target cells.

This manuscript describes a novel technique which allows the detection of intracellular gene expression after endocytosis of fluorescence-labeled nanoparticles directly in live cells. The method does not require manipulation of the cells and is not restricted with respect to the target gene or species.

Rilevazione di intracellulare genica in cellule vive di murini, umana e suina origine utilizzando nanoparticelle di fluorescenza marcata

The reprogramming of somatic cells to induced pluripotent stem cells (iPS) has successfully been performed in different mammalian species including mouse, ...

Nephrotoxin Microinjection in Zebrafish to Model Acute Kidney Injury

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid decline in renal function and development of the clinical syndrome known as acute kidney injury (AKI). Pharmacological agents used to treat medical circumstances ranging from bacterial infection to cancer, when administered individually or in combination with other drugs, can initiate AKI. Zebrafish are a useful animal model to study the chemical effects on renal function in vivo, as they form an embryonic kidney comprised of nephron functional units that are conserved with higher vertebrates, including humans. Further, zebrafish can be utilized to perform genetic and chemical screens, which provide opportunities to elucidate the cellular and molecular facets of AKI and develop therapeutic strategies such as the identification of nephroprotective molecules. Here, we demonstrate how microinjection into the zebrafish embryo can be utilized as a paradigm for nephrotoxin studies.

Renal injuries incurred from nephrotoxins, which include drugs ranging from antibiotics to chemotherapeutics, can result in complex disorders whose pathogenesis remains incompletely understood. This protocol demonstrates how zebrafish can be used for disease modeling of these conditions, which can be applied to the identification of renoprotective measures.

Nefrotossina microiniezione in Zebrafish per creare un modello danno renale acuto

The kidneys are susceptible to harm from exposure to chemicals they filter from the bloodstream. This can lead to organ injury associated with a rapid ...

Filtration Isolation of Nucleic Acids:  A Simple and Rapid DNA Extraction Method

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad to extract cellular DNA from whole blood in less than 2 min. The blood specimen is treated with detergent, mixed briefly and applied by pipet to the separation membrane. The lysate wicks into the blotting pad due to capillary action, capturing the genomic DNA on the surface of the separation membrane. The extracted DNA is retained on the membrane during a simple wash step wherein PCR inhibitors are wicked into the absorbent blotting pad. The membrane containing the entrapped DNA is then added to the PCR reaction without further purification. This simple method does not require laboratory equipment and can be easily implemented with inexpensive laboratory supplies. Here we describe a protocol for highly sensitive detection and quantitation of HIV-1 proviral DNA from 100 &#181;l whole blood as a model for early infant diagnosis of HIV that could readily be adapted to other genetic targets.

We describe here a simple and rapid paper-based DNA extraction method of HIV proviral DNA from whole blood detected by quantitative PCR. This protocol can be extended for use in detecting other genetic markers or using alternative amplification methods.

L&#39;isolamento di filtrazione di acidi nucleici: DNA metodo di estrazione semplice e veloce

FINA, filtration isolation of nucleic acids, is a novel extraction method which utilizes vertical filtration via a separation membrane and absorbent pad ...

A Rapid, Scalable Method for the Isolation, Functional Study, and Analysis of Cell-derived Extracellular Matrix

The extracellular matrix (ECM) is recognized as a diverse, dynamic, and complex environment that is involved in multiple cell-physiological and pathological processes. However, the isolation of ECM, from tissues or cell culture, is complicated by the insoluble and cross-linked nature of the assembled ECM and by the potential contamination of ECM extracts with cell surface and intracellular proteins. Here, we describe a method for use with cultured cells that is rapid and reliably removes cells to isolate a cell-derived ECM for downstream experimentation.
Through use of this method, the isolated ECM and its components can be visualized by in situ immunofluorescence microscopy. The dynamics of specific ECM proteins can be tracked by tracing the deposition of a tagged protein using fluorescence microscopy, both before and after the removal of cells. Alternatively, the isolated ECM can be extracted for biochemical analysis, such as sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. At larger scales, a full proteomics analysis of the isolated ECM by mass spectrometry can be conducted. By conducting ECM isolation under sterile conditions, sterile ECM layers can be obtained for functional or phenotypic studies with any cell of interest. The method can be applied to any adherent cell type, is relatively easy to perform, and can be linked to a wide repertoire of experimental designs.

The extracellular matrix plays a major role in defining the microenvironment of cells and in modulating cell behavior and phenotype. We describe a rapid method for the isolation of cell-derived extracellular matrix, which can be adapted to different scales for microscopic, biochemical, proteomic, or functional studies.

A Rapid, metodo scalabile per l&#39;isolamento, studio funzionale, e analisi di Cell-derivati ​​matrice extracellulare

The extracellular matrix (ECM) is recognized as a diverse, dynamic, and complex environment that is involved in multiple cell-physiological and ...

A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex signaling mechanisms underlying filopodial initiation, elongation and subsequent stabilization or retraction, it is crucial to determine the spatio-temporal protein activity in these dynamic structures. To analyze protein function in filopodia, we recently developed a semi-automated tracking algorithm that adapts to filopodial shape-changes, thus allowing parallel analysis of protrusion dynamics and relative protein concentration along the whole filopodial length. Here, we present a detailed step-by-step protocol for optimized cell handling, image acquisition and software analysis. We further provide instructions for the use of optional features during image analysis and data representation, as well as troubleshooting guidelines for all critical steps along the way. Finally, we also include a comparison of the described image analysis software with other programs available for filopodia quantification. Together, the presented protocol provides a framework for accurate analysis of protein dynamics in filopodial protrusions using image analysis software.

We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.

Un&#39;interfaccia utente grafica per il monitoraggio assistito della concentrazione di proteine ​​in protrusioni cellulari dinamiche

Filopodia are dynamic, finger-like cellular protrusions associated with migration and cell-cell communication. In order to better understand the complex ...

Transient Expression and Cellular Localization of Recombinant Proteins in Cultured Insect Cells

Heterologous protein expression systems are used for the production of recombinant proteins, the interpretation of cellular trafficking/localization, and the determination of the biochemical function of proteins at the sub-organismal level. Although baculovirus expression systems are increasingly used for protein production in numerous biotechnological, pharmaceutical, and industrial applications, nonlytic systems that do not involve viral infection have clear benefits but are often overlooked and underutilized. Here, we describe a method for generating nonlytic expression vectors and transient recombinant protein expression. This protocol allows for the efficient cellular localization of recombinant proteins and can be used to rapidly discern protein trafficking within the cell. We show the expression of four&#160;recombinant proteins in a commercially available insect cell line, including two aquaporin proteins from the insect Bemisia tabaci, as well as subcellular marker proteins specific for the cell plasma membrane and for intracellular lysosomes. All recombinant proteins were produced as chimeras with fluorescent protein markers at their carboxyl termini, which allows for the direct detection of the recombinant proteins. The double transfection of cells with plasmids harboring constructs for the genes of interest and a known subcellular marker allows for live cell imaging and improved validation of cellular protein localization.

Nonlytic insect cell expression systems are underutilized for production, cellular trafficking/localization, and recombinant protein functional analysis. Here, we describe methods to generate expression vectors and subsequent transient protein expression in commercially available lepidopteran cell lines. The co-localization of Bemisia tabaci aquaporins with subcellular fluorescent marker proteins is also presented.

Espressione transitoria e Localizzazione cellulare di proteine ​​ricombinanti in cellule in coltura per insetti

Heterologous protein expression systems are used for the production of recombinant proteins, the interpretation of cellular trafficking/localization, and ...

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions

Low oxygen levels (hypoxia) trigger a variety of adaptive responses with the Hypoxia-inducible factor 1 (HIF-1) complex acting as a master regulator. HIF-1 consists of a heterodimeric oxygen-regulated &#945; subunit (HIF-1&#945;) and constitutively expressed &#946; subunit (HIF-1&#946;) also known as aryl hydrocarbon receptor nuclear translocator (ARNT), regulating genes involved in diverse processes including angiogenesis, erythropoiesis and glycolysis. The identification of HIF-1 interacting proteins is key to the understanding of the hypoxia signaling pathway. Besides the regulation of HIF-1&#945; stability, hypoxia also triggers the nuclear translocation of many transcription factors including HIF-1&#945; and ARNT. Notably, most of the current methods used to study such protein-protein interactions (PPIs) are based on systems where protein levels are artificially increased through protein overexpression. Protein overexpression often leads to non-physiological results arising from temporal and spatial artifacts. Here we describe a modified co-immunoprecipitation protocol following hypoxia treatment using endogenous nuclear proteins, and as a proof of concept, to show the interaction between HIF-1&#945; and ARNT. In this protocol, the hypoxic cells were harvested under hypoxic conditions and the Dulbecco's Phosphate-Buffered Saline (DPBS) wash buffer was also pre-equilibrated to hypoxic conditions before usage to mitigate protein degradation or protein complex dissociation during reoxygenation. In addition, the nuclear fractions were subsequently extracted to concentrate and stabilize endogenous nuclear proteins and avoid possible spurious results often seen during protein overexpression. This protocol can be used to demonstrate endogenous and native interactions between transcription factors and transcriptional co-regulators under hypoxic conditions.

Here we describe a co-immunoprecipitation protocol to study protein-protein interactions between endogenous nuclear proteins under hypoxic conditions. This method is suitable for demonstration of the interactions between transcription factors and transcriptional co-regulators at hypoxia.

Analisi di co-immunoprecipitazione utilizzando proteine endogene nucleari da cellule coltivate in condizioni di ipossia

Low oxygen levels (hypoxia) trigger a variety of adaptive responses with the Hypoxia-inducible factor 1 (HIF-1) complex acting as a master regulator. ...