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Rees J. F.ANTIOXIDANT SYSTEMS: BASIC AND APPLIED ASPECTS GROUP LEADER
RESEARCH OVERVIEW The deep-sea has been long considered as a biological desert, if not as the place where the Devil himself resides. This view was changed by explorations starting near the end of the 19th Century, followed by the development of sophisticated fishing gears and submersibles. The slow and still very partial exploration demonstrated that the deep sea is far from being a vast barren ecosystem, and to the contrary, contains most of the Earth's biomass and biodiversity. Still, this environment remains very mysterious, and so are the physiological and biochemical adaptations of the organisms inhabiting this world. Research in the last 20 years revealed that an important parameter for any living organism on earth is related to oxygen toxicity. Indeed, reactive oxygen species (ROS) are a normal by-product of oxygen utilization by metabolic processes. Since ROS are far more powerful oxidants than triplet oxygen, they can react by most cell and tissue constituents, and either destroy the cell of inflict mutations in important genes. Transition metals are also key players in oxygen toxicity as they favour redox-processes leading to the production of highly toxic ROS. Acting as a barrier against these damages, antioxidative defence mechanisms are essential for cell survival. On one hand, they consist in an array of antioxidants (e.g. tocopherols, ascorbic acid) acting as stoechiometric scavengers of ROS. These ROS are now known to be key players in many pathological processes. On the other hand, they are organised as a intracellular compartimentalised, integrated, array of detoxification enzymes. The antioxidant status of deep-sea organisms should be an important factor affecting their survival and their depth-distribution. This had not received attention until very recently. Our research project is devoted to the fundamental and applied aspects of antioxidants in marine animals living in extreme environments. We are focusing our attention on pelagic and demersal deep-sea (250-5000 m) fishes on one hand, and on the fauna occurring at hydrothermal vents on the other. In the first case, our objective is the study of antioxidative mechanisms and their relationships with respiratory activity, either measured in situ with respirometers or estimated from metabolic indicators; Correlations between organochlorine contamination and levels of antioxidants are also studied. In the case of the hydrothermal organisms, our goal is to characterise their antioxidant arsenal in terms of enzymes types, structures and levels of expression, and small stoechiometric antioxidants.
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4/11/2011
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