Akira Kudo at Tokyo Tech and colleagues report that live-imaging and transcriptome analysis of medaka fish transgenic lines lead to immediate alteration of cells responsible for bone structure formation. These findings are important for assessing the effects microgravity on long term human space missions.
Space travel in a reduced gravity environment can have lasting effects on the body. For example, researches clearly show that astronauts undergo a significant drop in bone mineral density during space missions, but the precise molecular mechanisms responsible for such changes in bone structure are unclear.
Now, Akira Kudo at Tokyo Tech, together with scientists in Japan in support of other countries, performed remotely live-imaging (real time) for fluorescent signals derived from osteoblasts and osteoclasts of medaka fish after only one day of exposure to microgravity aboard the International Space Station (ISS). They found increases in both osteoblast and osteoclast specific promoter-driven GFP and DsRed signals one day after launch, and continued for up to eight days.
In their experiments, the team used four different double medaka transgenic lines focusing on up-regulation of fluorescent signals of osteoblasts and osteoclasts to clarify the effect of gravity on the interaction of osteoblast-osteoclast. They also studied changes in the gene expression in the transgenic fish by so-celled transcriptome analysis.
These findings suggest that exposure to microgravity induced an immediate “dynamic alteration of gene expressions in osteoblasts and osteoclasts.” Namely, these experiments based on real time imaging of medaka from Earth and transcriptome analysis could be the prelude to the establishment of new scientific areas of research in “gravitational biology”.