Scott Kelly, a former ISS crew commander, is no longer the complete twin of his brother Mark Kelly, LiveScience reports.
“When Scott went into space, there was a whole bunch of changes in the work of individual genes in his body. Some of them disappeared after returning to Earth, but other changes did not disappear, including changes in the functioning of the immune system and the retina of the eyes. Such a large number of changes suggests that the body was literally trying to adapt to a completely new, “alien” habitat,”said Christopher Mason, project manager for NASA's Twins Study.
The Kelly brothers participated in an experiment by NASA: doctors tried to assess how life in orbit affects human health. Scott and Mark are identical twins with a similar lifestyle, both astronauts. The latter circumstance made the experiment as "pure" and rigorous as possible.
After taking samples of blood and other tissues before and after Scott's one-year mission to the ISS, NASA doctors compared them with similar samples received from Mark. This revealed the interesting differences that life in space has brought about.
For example, molecular biologists have found that so-called telomeres, the ends of chromosomes that protect them from breakage, have become longer in space. This indicates some "rejuvenation" of Scott Kelly's cells. On the other hand, there were also negative changes - the microflora of his intestines changed: inflammations began to appear more often in the body of the ISS commander, and the condition of his bones deteriorated somewhat due to life in zero gravity.
Recently, Mason and his colleagues analyzed how the DNA structure and the activity of some of Scott Kelly's genes have changed. As scientists joke, now he cannot be considered a full-fledged twin of Mark, about seven percent of his genes do not work at all the way they functioned before the flight to the ISS.
In addition to the DNA regions associated with the work of the immune system and the eyes, the work of those genes that are responsible for the formation of bones, repair of mutations and the reaction to a lack of oxygen and an excess of carbon dioxide have changed the most. According to geneticists, not all of these changes were of the same type - some genes were “turned off”, while others, on the contrary, became more active.
Mason's team has not yet completed data analysis. Now scientists are trying to find the so-called space genes that are responsible for human adaptation to life in zero gravity. Their discovery, biologists hope, will help to understand how best to protect a person when flying to Mars or while living on the surface of the Moon and other celestial bodies.
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