Fish in Space Shedding Light on Gravitational Biology

Abstract

Space flight in an environment with reduced gravity has severe effects on the body. Astronauts suffer from a significant decrease in bone mineral density during space missions, but the molecular mechanisms responsible for such changes in bone density are unclear. To identify these mechanisms, unique experiments on medaka fish were performed twice at the International Space Station (ISS). One was a two-month long experiment for the analysis of bone growth, which revealed a decrease in the mineral density of pharyngeal bones. Another was a short-term experiment for live imaging of transgenic medaka lines and transcriptome analysis during 8 days, which revealed an increase in the expression levels of five genes. Overall, these studies on medaka fish provided an initial explanation of the process.