The NASA Twins Study has found that being in space leads to DNA methylation and expression changes, Space.com reports.
Astronaut Scott Kelly spent about a year in space at the International Space Station, while his twin brother Mark Kelly, a former astronaut, stayed behind on Earth. As part of the study, NASA conducted pre-, during, and post-flight tests on the brothers — including sequencing their genomes — with the aim of discovering how being in space affects the human body.
Earlier this year, researchers reported that Scott Kelly's telomeres appeared to have lengthened during his time in space, as compared to Mark's, contrary to what the researchers had expected. Preliminary reports had also previously indicated differences in methylation and gene expression within samples from Scott Kelly, suggesting that being in space is stressful.
Weill Cornell Medicine's Christopher Mason now says that this increase in methylation and gene expression appears to occur upon arrival in space and persists for a while after returning to Earth. "Some of the most exciting things that we've seen from looking at gene expression in space is that we really see an explosion, like fireworks taking off, as soon as the human body gets into space," Mason says in a statement.
NASA officials tell Space.com that they expect to publish their final results next year.