title: Mitochondrial uncoupling as a regulator of life-history trajectories in birds: an experimental study in the zebra finch.
abstract: Mitochondria have a fundamental role in the transduction of energy from food into ATP. The coupling between food oxidation and ATP production is never perfect, but may nevertheless be of evolutionary significance. The 'uncoupling to survive' hypothesis suggests that 'mild' mitochondrial uncoupling evolved as a protective mechanism against the excessive production of damaging reactive oxygen species (ROS). Because resource allocation and ROS production are thought to shape animal life histories, alternative life-history trajectories might be driven by individual variation in the degree of mitochondrial uncoupling. We tested this hypothesis in a small bird species, the zebra finch (Taeniopygia guttata), by treating adults with the artificial mitochondrial uncoupler 2,4-dinitrophenol (DNP) over a 32-month period. In agreement with our expectations, the uncoupling treatment increased metabolic rate. However, we found no evidence that treated birds enjoyed lower oxidative stress levels or greater survival rates, in contrast to previous results in other taxa. In vitro experiments revealed lower sensitivity of ROS production to DNP in mitochondria isolated from skeletal muscles of zebra finch than mouse. In addition, we found significant reductions in the number of eggs laid and in the inflammatory immune response in treated birds. Altogether, our data suggest that the 'uncoupling to survive' hypothesis may not be applicable for zebra finches, presumably because of lower effects of mitochondrial uncoupling on mitochondrial ROS production in birds than in mammals. Nevertheless, mitochondrial uncoupling appeared to be a potential life-history regulator of traits such as fecundity and immunity at adulthood, even with food supplied ad libitum.
authors: University of Angers, Groupe Écologie et Conservation des Vertébrés (GECCO), 49045 Angers, Cedex 01, France antoine.stier@gmail.com.
authors: Antoine
authors: A
authors: Stier
authors: Department of Ecology and Evolution, University of Lausanne, Biophore 1015 Lausanne-Dorigny, Switzerland.
authors: Pierre
authors: P
authors: Bize
authors: Laboratoire d'Écologie des Hydrosystèmes Naturels et Anthropisés, CNRS UMR 5023, Université de Lyon, 69622 Villeurbanne Cedex, France.
authors: Damien
authors: D
authors: Roussel
authors: University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors: Quentin
authors: Q
authors: Schull
authors: University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors: Sylvie
authors: S
authors: Massemin
authors: University of Strasbourg, Institut Pluridisciplinaire Hubert Curien, 67037 Strasbourg Cedex, France Département d'Ecologie, Physiologie et Ethologie (DEPE), CNRS UMR 7178, 23 rue Becquerel, 67087 Strasbourg Cedex 2, France.
authors: François
authors: F
authors: Criscuolo
mesh_terms: D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D005298:Fertility; D046369:Finches / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D007113:Immunity, Innate; D007249:Inflammation; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D019297:2,4-Dinitrophenol
keywords: Bird; Free radical theory of ageing; Life-history trade-off; Mitochondria; Oxidative stress; Reactive oxygen species; Uncoupling