NASA scientists in an unprecedented study have found that space travel may alter gene expression. The study involved astronaut Scott Kelly, who spent a year in space and his identical twin Mark who stayed on Earth. From the lengths of the twins’ chromosomes to the microbiomes in their guts, “almost everyone is reporting that we see differences”, Christopher Mason, a geneticist at Weill Cornell Medical College in New York City, was quoted as saying to scientificamerican.com.
The changes that are likely attributable to Scott’s time in orbit include alterations to gene expression, DNA methylation — the reversible addition of a chemical marker that can affect gene expression — and other biological markers. DNA methylation decreased in Scott during flight and increased in Mark over the same period. Levels for both men returned close to pre-flight levels after Scott came back to Earth, according to the preliminary results published in the journal Nature. “What this means isn’t yet clear,” said Andrew Feinberg, a geneticist at Johns Hopkins University in Maryland, US.