|Enfer et paradis: la toxicité de l'oxygène chez les organismes abyssaux = Heaven and Hell: Oxygen toxicity in abyssal organisms|
Rees, J.F.; Zal, F.; Thomé, J.P. (2007). Enfer et paradis: la toxicité de l'oxygène chez les organismes abyssaux = Heaven and Hell: Oxygen toxicity in abyssal organisms. Océanis (Paris) 30(3): 277-291
In: Océanis (Paris). Institut Océanographique: Paris. ISSN 0182-0745, more
Abyssal zone; Oxygen; Toxicity; Marine
abyss; antioxidant; hydrothermal vents; bioluminescence
Oxygen, although an essential molecule for animal life, may become toxic when converted into reactive species, notably during mitochondrial respiration. These compounds react with most cellular components and may result in cell death or carcinogenesis. Whereas resistance of terrestrial organisms to oxygen toxicity is fairly well studied and understood, notably in the framework of pathological studies, it is largely unexplored in deep-sea organisms. There, contrasted situations occur. It may be Heaven for pelagic animals with a lowered body temperature and a lesser environmental oxygen concentration, sheltered from photochemical reactions that generate singulet oxygen and hydrogen peroxide in surface seawater. Moreover, respiratory metabolism decreases exponentially with depth. Consequently these animals face a much reduced oxidative stress. Bioluminescence, fairly common in deep sea animals, may be derived from antioxidant defence systems which have become less necessary with the colonization of deep sea. However, these animals could be threatened by pollution, some pollutants such as organochloride compounds generating oxidative stress. But it may be Hell for deep-sea hydrothermal vent animals where high temperatures and elevated concentration of metals and radioactive elements prevail, and where sulfur compounds may counter antioxidative mechanisms. Their enzymatic defences are specific with some enzymes being directed towards oxygen reactive species originating from respiratory metabolism while others could be directed towards exogenous threats.