Resistance of the anhydrobiotic eutardigrade Paramacrobiotus richtersi to space flight (LIFE-TARSE mission on FOTON-M3)

The project 'TArdigrade Resistance to Space Effects (TARSE)' analysed the effects of space microgravity and radiations stresses on the eutardigrade Paramacrobiotus richtersi allowing, for the first time, a comparison between hydrated and desiccated animals. TARSE experiments were part of the mission LIFE on FOTON-M3 that flew at an altitude between 250 and 290km (Low-Earth Orbit) for 12days in September 2007. The experimental units of the TARSE project were housed in the BIOKON facility installed inside the Russian spacecraft FOTON-M3. In this paper, data on survival rate, Hsps expression (70 and 90kDa) and genomic DNA integrity (double-strand breaks) of flown desiccated animals, and from specimens of ground control experiments are presented. For the flown experiments, microcosms of dry leaf litter collected in the field containing naturally desiccated specimens and blot filter papers containing specimens desiccated in laboratory under controlled conditions were used. After the space flight, desiccated animals had high survival rates (from 79% to 95%) showing a similar survival rate to that observed in ground controls. No visible damages to double-strand genomic DNA were observed in all desiccated samples, whereas Hsp70 and Hsp90 levels of flown tardigrades were higher than those of ground controls. These data combined with earlier published results on hydrated specimens of P. richtersi indicate that tardigrades have the ability to tolerate for a short time period stresses typical of the extraterrestrial environment such as microgravity and radiations.