Rotifer in space (RISE): a model organism for extreme stress conditions

Bdelloid rotifers are micro-invertebrates distributed worldwide, from temperate to most extreme areas of the planet like Antarctica or Atacama Desert. They have colonized any habitat where liquid water is temporarily available, including terrestrial environments such as soil, mosses and lichens, tolerating desiccation and other stress such as high doses of ionizing radiations thanks to their ability to repair DNA double strand breaks (DSBs).
Space exposure experiments from the last fifteen years have unexpectedly shown that several terrestrial organisms, including some multi-cellular species, are able to survive in open space without protection. The robustness of bdelloid rotifers suggests that these tiny creatures can possibly be added to the still restricted list of animals that can deal with the exposure to harsh condition of space. Adineta vaga, with its unique characteristics and a draft genome available, was selected by ESA (European Space Agency) as a model system to study extreme resistance of organisms exposed to space environment. Through ground experiments, we documented the resistance of desiccated A. vaga individuals exposed to increasing doses of X-ray, protons and Fe ions, as well as simulated space environment (high vacuum, temperature cycles, simulated solar spectrum) in order to design optimally further astrobiology experiments.
The RISE project aims to answer the following key questions:
• Rob-1 flight (using hydrated Adineta vaga rotifers inside ISS): how is this micro-organism affected by space travel?
• Rob-2 flight (using desiccated Adineta vaga rotifers inside ISS): are DNA repair mechanisms affected by space environment? Can rotifers with a broken genome be rehydrated in microgravity and start DNA repair, as on earth? Do they reproduce and are the descendants still identical to the parental line?
• Rotifer-A flight (using desiccated rotifers exposed to the space environment outisde ISS, scheduled in 2025): Can bdelloid rotifers survive space vacuum, UV, cosmic radiation exposure and through what mechanisms? Ultimately, what are the limits of life?
Rob-1 and Rob-2 samples were successfully recovered and data analysis is ongoing.