title: In situ quantification of mitochondrial respiration in permeabilized fibers of a marine invertebrate with low aerobic capacity.
abstract: The aim of this study was to design a protocol to allow the assessment of normal and alternative pathways for electron transport in mitochondria using an in situ approach (on permeabilized fibers) in high-resolution respirometry. We measured the oxygen consumption of permeabilized fibers from Nereis (Neanthes) virens with different substrates and the presence of ADP. To estimate the alternative oxidase (AOX) activity, antimycin A was introduced in order to inhibit complex III. Moreover, the apparent complex IV (COX) excess capacity was evaluated using different substrates to assess the implication of this complex in the partitioning of electrons during its progressive inhibition. Our in situ method enabled to quantify the activity of the normal COX pathway as well as the AOX pathway when different substrates were oxidized by either complex I, complex II or both. Using this approach, we confirmed that according to the substrates used, each pathway has a different role and consequently is otherwise involved in the partitioning of electrons through the electron transport system, and suggested that the AOX activity is triggered not only by the redox state of the cell but also by the type of substrates provided to mitochondria.
authors.affiliation: Laboratoire de biologie intégrative, Département de Biologie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, Québec, Canada G5L 3A1. n.pichaud@unsw.edu.au
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pichaud
authors.forename: Pierre
authors.initials: P
authors.lastname: Rioux
authors.forename: Pierre U
authors.initials: PU
authors.lastname: Blier
mesh_terms: D000332:Aerobiosis; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D002463:Cell Membrane Permeability; D019069:Cell Respiration; D045222:Electron Transport Chain Complex Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004734:Energy Metabolism; D007700:Kinetics; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D011077:Polychaeta / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D045222:Electron Transport Chain Complex Proteins; D000968:Antimycin A; D010088:Oxidoreductases