One Identical Twin Spent 1 year in Space and It May Have Permanently Changed 7 Percent of His DNA
Scott and Mark Kelly are identical twins with the same two sets of matching DNA. In a unique experiment, NASA sent Scott into space for 1 year in order for them to observe how space flight changes the human body and brain.
When Scott Kelly, a veteran astronaut of 4 space flights, stood up on stage after 1 year in space, he was 2 inches taller. This newfound height actually turned out to be a temporary and was caused by his spine being physically stretched in a gravity-free environment and not as a result of his genes being altered.
After further research, NASA are reporting many tweaks in his genes that are not present in his brother Mark, some temporary but others have been longer lasting.
“When he went up into space it was like fireworks of gene expression," Christopher Mason, a principal investigator on the NASA twins study. But the changes that seem to have stuck around include changes in immune system function and retinal function related to his eye health."
According to Mason, some 7% of Scott's genes have not returned to normal since he landed back on Earth more than two years ago. Those changes appear to have occurred in genes that control functions related to Kelly's immune system, bone formation, and DNA repair, as well as in those involved in responding to an oxygen-depleted or carbon-dioxide rich environment.
"With a lot of these changes, it's as if the body is trying to understand this, quite literally, alien environment and respond to that" Mason said.In many respects, “Kelly's genes display the hallmarks of a body reacting to what it perceives as a threat” he added. "Oftentimes when the body encounters something foreign, an immune response is activated. The body thinks there’s a reason to defend itself. We know there are aspects of being in space that are not a pleasant experience, and this is the molecular manifestation of the body responding to that stress."
Whilst NASA is yet to make all of the study results available to the public, some of the interesting findings we know about include:
- Scott's telomeres got longer, then shrunk back to normal: The caps on the of Scott’s chromosomes (telomeres) became longer than Mark’s whilst in space, they quickly returned to their normal length back on earth. “That is exactly the opposite of what we thought,” Susan Bailey, a radiation biologist at Colorado State University in Fort Collins. This was because shorter telomeres are generally associated with getting older. Scientists are still studying what this means, but it could be linked to getting more exercise and eating fewer calories while in space, according to NASA.
- Scott's genetic expression changed in a variety of ways: Scott's genes showed both increased and decreased levels of methylation, a process that results in genes getting turned on and off. “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,”. This could indicate that genes are more sensitive to a changing environment whether on Earth or in space.
- The twins hosted different gut bacteria: Researchers noted differences between Scott's and Mark's gut bacteria (essentially the microbes that aid in digestion) throughout the year-long study. This was probably a result of their different diets and environments, NASA said.
- Scientists are looking for what they're calling a ‘space gene’: By sequencing the RNA in the twins' white blood cells, researchers found more than 200,000 RNA molecules that were expressed differently between the brothers. It is normal for twins to have unique mutations in their genome, but scientists are "looking closer to see if a 'space gene' could have been activated while Scott was in space," NASA said.
NASA is still combing through the results of the study and expects to release the full set later this year. That research will inform space missions — including potential trips to Mars — for years to come.