The production of Reactive Oxygen Species (ROS) during desiccation processes is documented in bacteria and plants, whereas studies on animals are in practice lacking. In this study we investigated the response to dehydration with respect to the ROS production during the kinetic of the desiccation process and the short and long-time permanence in the anhydrobiotic state. We hypothesized that ROS production, and thus oxidative damage, may be greater in animals maintained desiccated for long-time than in animals maintained dry just for one day. The tardigrade Paramacrobiotus richtersi was used as a target animal. In parallel, oxidative stress was assessed in hydrated P. richtersi as control. Adults were experimentally dehydrated in laboratory using an optimal desiccation protocol to achieve a 100% survival rate of P. richtersi. Animals were maintained desiccated (at 3% RH and 20°C) from 1 to 40 days. Intracellular ROS production during rehydration was evaluated in the “storage cells” (free-floating cells in the tardigrade body cavity), after treatment of the tardigrades with the probe 2,7-dichlorodihydrofluorescein-diacetate (DCFH2-DA). The amount of green fluorescent oxidation product (DCF), which reflects the reaction of the probe with intracellular free radicals, was measure by a laser scanner confocal microscope. The desiccation process does not produce a high amount of ROS, even though previous studies on the same species, P. richtersi, demonstrated an increase of antioxidant enzyme activity in desiccated specimens with respect to hydrated ones. Instead, the long-time permanence in anhydrobiosis (20 days) produces a significant increase of ROS, as evidenced after three and twelve hours from rehydration. The collection of data about the permanence in anhydrobiosis for 40 days is in progress. The high amount of ROS detected in animals maintained dry for long-time, and consequently the oxidative molecular damages, justifies that tardigrade survival decreases with the time spent in a dry state.
Desiccation tolerance and production of Reactive Oxygen Species (ROS) in the anhydrobiotic water bear Paramacrobiotus richters / Giovannini, Ilaria; Guidetti, Roberto; Rebecchi, Lorena. - STAMPA. - 1:(2014), pp. 84-84. (Intervento presentato al convegno New Frontiers in anhydrobiosis tenutosi a Pornichet nel 23-27 March 2014).