Experiment

JAXA's 3rd Mouse breeding mission finished

The 3rd Mouse breeding mission (for 31 days from April 4 to May 5), which had been conducted on board the Pressurized Module of Japanese Experiment Module (JEM) "Kibo" , completed and the space-bred mice returned to Earth aboard the Dragon spacecraft (SpX-14) on May 6 (Japan Standard Time, JST).

On May 7, the mouse cage for return was handed over from NASA to JAXA, which subsequently confirmed the survival of all mice. In this mission, six knock-out mice with deleted the genes of Nrf2, a control factor involved in biological stress defense, (mice highly sensitive to stress) and six control mice that were native, 12 mice in total, had been bred in space for a long term. The mission has brought the world's first achievement of the long duration stay in space and return all alive of gene-knockout mice.

While staying in space, humans face many kinds of medical risks, so-called space stresses, including oxidative stress, DNA disorder, and cell death caused by cosmic radiation and interference in intracellular signal transduction caused by mechanical stress due to the microgravity environment.
To elucidate these risks, avoid the space stresses, and examine the measures is an essential issue to space exploration.

This breeding mission focuses on Nrf2, a transcription factor which controls a group of biological defense genes and is expected to play a defensive role in space stress. The mission is intended to return Nrf2-deficient mice and native mice to Earth after being bred on board for a long term, about 30 days, clarify the contribution of activated Nrf2 contributes to biological defense to space stress, and demonstrate the effectiveness of Nrf2-inducing agent in reducing risks in space.

In addition,　the success achieved by the mission opened up a new way by analyzing how space stress affects the impact of deletion of each gene on many gene-knockout mouse strains which are being produced around the world aimed for human pathology research. We are now literally in the Decade of Space Mouse. In that decade, for example, studies on promotion of health and longevity on Earth is expected to be further advanced by utilizing the space environment where bone loss and sarcopenia are accelerated.

*All times are Japan Standard Time (JST)