P29-5 Sat Jan 2 Mitochondrial capacity and reactive oxygen species production in response to short-term hypoxia and reoxygenation in the ocean quahog, Arctica islandica Steffen, JBM*; Haider, F; Sokolov, EP; Sokolova, IM; University of Rostock, Germany; University of Rostock, Germany; Leibniz-Institute for Baltic Research, Warnemuende, Germany; University of Rostock, Germany jennifer.steffen@uni-rostock.de
Oxygen fluctuation is a common phenomenon in marine waters. Hypoxia/reoxygenation (H/R) stress can negatively affect energy metabolism, since oxygen deficiency impairs mitochondrial ATP generation, whereas a surplus of oxygen causes mitochondrial damage by oxidative stress mechanisms. The long lived ocean quahog, Arctica islandica, is known for its hypoxia tolerance associated metabolic rate depression, yet the underlying mechanisms that sustain their mitochondrial integrity and function during oxygen fluctuations are not yet well understood. We used the top-down metabolic control analysis (MCA) to determine mitochondrial capacity and control of mitochondrial subsystems over bioenergetics in response to short-term hypoxia (24h <0.01% O2) and subsequent reoxygenation (1.5h 21% O2) in the hypoxia tolerant ocean quahog with control animals kept under normoxic conditions (21% O2). We hypothesised that the ocean quahog shows a coordinated reorganization of its mitochondrial subsystems and regulated reactive oxygen species (ROS) production to maintain mitochondrial functions contributing to its H/R resilience. To test these hypotheses, mitochondrial oxygen flux capacity and control over the respiratory flux of hepatopancreas mitochondria of the studied species were analysed by high resolution respirometry, along with simultaneous fluorometric ROS production associated with membrane potential changes. The results of this study shed light on mechanisms of mitochondrial flux control and resilience to hypoxia in stress-tolerant marine bivalves.
