title: Avian erythrocytes have functional mitochondria, opening novel perspectives for birds as animal models in the study of ageing.
abstract: BACKGROUND
  In contrast to mammalian erythrocytes, which have lost their nucleus and mitochondria during maturation, the erythrocytes of almost all other vertebrate species are nucleated throughout their lifespan. Little research has been done however to test for the presence and functionality of mitochondria in these cells, especially for birds. Here, we investigated those two points in erythrocytes of one common avian model: the zebra finch (Taeniopygia guttata).
  
  
  RESULTS
  Transmission electron microscopy showed the presence of mitochondria in erythrocytes of this small passerine bird, especially after removal of haemoglobin interferences. High-resolution respirometry revealed increased or decreased rates of oxygen consumption by erythrocytes in response to the addition of respiratory chain substrates or inhibitors, respectively. Fluorometric assays confirmed the production of mitochondrial superoxide by avian erythrocytes. Interestingly, measurements of plasmatic oxidative markers indicated lower oxidative stress in blood of the zebra finch compared to a size-matched mammalian model, the mouse.
  
  
  CONCLUSIONS
  Altogether, those findings demonstrate that avian erythrocytes possess functional mitochondria in terms of respiratory activities and reactive oxygen species (ROS) production. Interestingly, since blood oxidative stress was lower for our avian model compared to a size-matched mammalian, our results also challenge the idea that mitochondrial ROS production could have been one actor leading to this loss during the course of evolution. Opportunities to assess mitochondrial functioning in avian erythrocytes open new perspectives in the use of birds as models for longitudinal studies of ageing via lifelong blood sampling of the same subjects.
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, University of Strasbourg, Strasbourg, France. antoine.stier@gmail.com.
authors.forename: Antoine
authors.initials: A
authors.lastname: Stier
authors.forename: Pierre
authors.initials: P
authors.lastname: Bize
authors.forename: Quentin
authors.initials: Q
authors.lastname: Schull
authors.forename: Joffrey
authors.initials: J
authors.lastname: Zoll
authors.forename: François
authors.initials: F
authors.lastname: Singh
authors.forename: Bernard
authors.initials: B
authors.lastname: Geny
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gros
authors.forename: Cathy
authors.initials: C
authors.lastname: Royer
authors.forename: Sylvie
authors.initials: S
authors.lastname: Massemin
authors.forename: François
authors.initials: F
authors.lastname: Criscuolo