WASHINGTON, Sept. 9 (Xinhua) -- Water bears are the first animals in the world to have survived exposure to the vacuum and radiation of space, according to a report published Tuesday in U.S. journal Current Biology.

    Nearly a year ago, Ingemar Jonsson, an ecologist from Kristianstad University in Sweden, had some 3,000 microscopic water bears sent up on a 12-day space trip.

    The aim of the research project was to find out more about the basic physiology of tardigrades by seeing if they can survive in a space environment.

    Now Jonsson and his European colleagues reported their results." Our principal finding is that the space vacuum, which entails extreme dehydration, and cosmic radiation were not a problem for water bears. On the other hand, the ultraviolet radiation in spaceis harmful to water bears, although a few individual can even survive that," says Jonsson.

    The next challenge for the researchers is to try to understand the mechanisms behind this exceptional tolerance in water bears.

    Jonsson suspects that even the water bears that got through the space trip without any trouble may in fact have incurred DNA damage, but that the animals managed to repair this damage.

    "All knowledge involving the repair of genetic damage is central to the field of medicine," says Jonsson. "One problem with radiation therapy in treating cancer today is that healthy cells are also harmed. If we can document and show that there are special molecules involved in DNA repair in multicellular animals like tardigrades, we might be able to further the development of radiation therapy."

    Water bears are multicellular, invertebrate animals about one millimeter in size. They exist in nearly all ecosystems of the world. What makes them unique is that they can survive repeated dehydration and can lose nearly all the water they have in their bodies. When dehydrated, they enter into a dormant state in which the body contracts and metabolism ceases. In this death-like dormant state, water bears manage to maintain the structures in their cells until water is available and they can be active again.