Preventive antioxidant responses to extreme oxygen level fluctuation in a subterranean crustacean

The principal aim of this work was to explore the responses of the groundwater crustacean Niphargus rhenorhodanensis to oxidative stress caused by short- and long-term drastic variations in oxygen level. To this end, we investigated thiobarbituric acid reactive substances (TBARS) levels and anti-oxidative enzyme (SOD and GPx) activities during 24 h anoxia and post-anoxia recovery, and during 10 days of severe hypoxia and post-hypoxia recovery. We observed a decrease in TBARS amounts during recovery from severe hypoxia. Parallel to these results, we observed an overactivation of SOD activity after a 24 h anoxic stress. GPx activity measured at the end of anoxia or severe hypoxia and in the early hours of post-stress recovery also showed an overactivation compared to the control group. We can hypothesize that this overproduction of GPx corresponded to an anticipatory mechanism coping with the overproduction of reactive oxygen species (ROS) during the recovery phase in subterranean animals. This response could be considered as a major asset for life in alternately normoxic and hypoxic conditions, and therefore in extreme biotopes such as groundwaters.