title: Discrimination of respiratory dysfunction in yeast mutants by confocal microscopy, image, and flow cytometry.
abstract: Living yeast cells can be selectively stained with the lipophilic cationic cyanine dye DiOC6(3) in a mitochondrial membrane potential-dependent manner. Our study extends the use of flow cytometric analysis and sorting to DiOC6(3)-stained yeast cells. Experimental conditions were developed that prevented the toxic side effect of the probe and gave a quantitative correlation between fluorescence and mitochondrial membrane potential, without any staining of other membranes. The localization of the fluorochrome was checked by confocal microscopy and image cytometry. The mitochondrial membrane alterations were also tested through cardiolipin staining with nonyl acridine orange. Differences in light scattering and in fluorescence were detected in mutants (rho-, rho degrees, mit-, or pet-) and wild-type (rho+mit+) populations of yeast. The dye uptake of respiratory-deficient yeast strains was significantly reduced as compared to that of the wild-type. Application of an uncoupler (mCICCP), which collapsed the mitochondrial membrane potential (alphapsi(m)), led to a drastic reduction of the dye uptake. It was observed that a decrease in deltapsi(m), was usually correlated with a decrease in cardiolipin stainability by nonyl acridine orange (NAO). Quantitative flow cytometry is a fast and reproducible technique for rapid screening of yeast strains that might be suspected of respiratory dysfunction and/or mitochondrial structural changes. We give evidence that it is an adequate method to characterize and isolate respiratory mutants through sorting procedure, with selective enrichment of the population studied in respiring or non-respiring yeast cells. Confocal microscopy and image cytometry corroborate the flow cytometry results.
authors.affiliation: Centre de Génétique Moléculaire, CNRS UPR 2420 associé a l'Université Pierre et Marie Curie Gif-sur-Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Petit
authors.forename: N
authors.initials: N
authors.lastname: Glab
authors.forename: D
authors.initials: D
authors.lastname: Marie
authors.forename: H
authors.initials: H
authors.lastname: Kieffer
authors.forename: P
authors.initials: P
authors.lastname: Métézeau
mesh_terms: D000165:Acridine Orange / Q000031:analogs & derivatives* / Q000494:pharmacology; D002232:Carbocyanines; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002308:Cardiolipins / Q000378:metabolism; D002455:Cell Division / Q000235:genetics; D019069:Cell Respiration / Q000187:drug effects / Q000235:genetics*; D002478:Cells, Cultured; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods*; D005456:Fluorescent Dyes; D019044:Image Cytometry / Q000295:instrumentation / Q000379:methods*; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009154:Mutation / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D002232:Carbocyanines; D002308:Cardiolipins; D005456:Fluorescent Dyes; D014475:Uncoupling Agents; C056258:N(10)-nonylacridine orange; C007392:3,3'-dihexyl-2,2'-oxacarbocyanine; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000165:Acridine Orange