Molecular biology via epigenetics in space: the cosmonaut’s genes

After a year in space, the genes of U.S. astronaut Scott Kelly have changed, NASA reports. Dirk Schubeler explains why.

Suddenly seven percent different from his twin: US astronaut Scott Kelly Photo: dpa

site: Mr. Schubeler, after a year on the International Space Station, the genes of NASA astronaut Scott Kelly have changed by seven percent compared to those of his identical twin brother on Earth. Why does life in space change our genes?

Dirk Schubeler: It’s not the genetic sequence that has changed. If that were the case, no Austronaut could survive in space. Rather, the genes have been changed epigenetically. That is, which genes are active and which are not. There are chemical modifications to the DNA and RNA, so-called methyl groups, that have changed.

How does that happen?

Our gene expression, that is, which of our genes are active, depends, among other things, on our living conditions, our diet, our environment. The environment is of course completely different in space, and this also changes the epigenetic patterns. For example, the oxygen saturation is lower there, which is a stress situation for the body. The body finds a response to that, and changes the composition of the blood cells, for example.

I suspect if you took the one twin into high alpine territory, you would see similar changes. So how much the result has to do with space per se is something we can’t say until the data is available in detail. So far, NASA has not published its study and has been vague.

Do we inherit these epigentic changes?

I am skeptical. If anything, only a very small part is heritable. In the germ line, i.e. when the egg and sperm are produced, these markers actually disappear completely. How completely, that is the question. But the evidence that epigenetic changes are inherited is thin. I am among those who are rather critical of this thesis, given the current data.

is a professor of molecular biology at the Friedrich Miescher Institute for Biomedical Research in Basel and researches gene expression.

Can a positive mutation also result from the changes in space?

We speak of a mutation when the DNA sequence changes. A mutation is initially something random, it’s like a shotgun blast. Mutations are of course the source of variations that ultimately produce evolutionary changes, but first of all the vast majority of them are harmful. It is not for nothing that we avoid, among other things, radioactive radiation, which triggers mutations.

For example, you don’t see the chance of adapting better to life in space over time?

Not really. Rather, we will try to adapt the conditions in space in such a way that the organism is stressed as little as possible. That’s exactly what NASA wants to research with this and similar studies: How much stress space travel means for the human body – and whether longer journeys through space are at all justifiable.