Oxygen, telomeres and sex: experimental elucidation of oxidative stress effects in life history evolution

Description du projet

Impact in vivo du stress oxydatif

Le stress oxydatif est généré par une quantité excessive de radicaux libres, qui sont susceptibles d’endommager les cellules. Il reste toutefois à déterminer si le stress oxydatif exerce une influence sur les processus in vivo que sont notamment la croissance, la reproduction et la survie. Pour combler cette lacune, le projet UnravelOxStress, financé par l’UE, étudie l’effet direct du stress oxydatif sans interventions pharmacologiques, qui sont couramment utilisées dans le cadre des expériences. Les chercheurs soumettront les oiseaux à des niveaux d’oxygène plus élevés (air hyperoxique) afin d’augmenter le stress oxydatif et d’analyser l’aptitude à la reproduction et le vieillissement cellulaire à l’aide de la longueur des télomères. L’approche d’UnravelOxStress contournera les limites expérimentales précédentes, notamment les effets secondaires des médicaments utilisés pour induire le stress oxydatif.

Objectif

Oxidative stress -the imbalance between antioxidants and reactive oxygen species (ROS) generated during aerobic respiration- has often been hypothesized to play a central role in disease and life history evolution, including ageing. However, whether oxidative stress modulates patterns of growth, reproduction and survival is still an enigma, largely because the high reactivity of ROS makes oxidative stress difficult to measure. In addition to this, the experimental manipulation of oxidative stress levels without toxic side-effects has also proven difficult. I propose to elucidate oxidative stress effects on (cellular) ageing and key fitness components using a novel non-invasive experimental approach that bypasses side effects of pharmacological approaches. To this end, I will expose birds to hyperoxic air, which is known to increase oxidative stress. This will be combined with alleviation of oxidative stress through the administration of antioxidants in a 2x2 design, to verify that the observed effects of hyperoxia can be attributed to oxidative stress. First, I will test the effect of both interventions on sexual ornamentation, sperm quality and future reproduction using captive adult zebra finches. Second, by applying the same 2x2 design to nestlings I will test how oxidative stress affects future reproduction and cellular ageing (telomere attrition). The latter aims to resolve the long-standing question whether the effect of oxidative stress in vitro is also observed in vivo, at physiological oxidative stress levels. In this way, this Action will shed light on the conundrum of the roles of oxidative stress in life history evolution and telomere dynamics. Moreover, through mutual knowledge transfer and the extension of my scientific network (both in the host institution and through dissemination events that I will organize around Europe), this Action will critically advance my career towards the establishment as independent researcher.