Three years ago, the American astronaut Scott Kellyreturned to Earth. His return from the International Space Station on March 1, 2016 completed a record-for-US stay of 340 days in space under a medical microscope. His twin brother Mark Kelly (who was also an astronaut) was under the close supervision of doctors on Earth. The two of these twins offered a unique opportunity to explore how the human body reacts to long periods of stay in space, and to understand what can happen when traveling, for example, to Mars.
And now, after more than three years, we finallywe get a clear picture of what microgravity, radiation, and the space environment have done with Scott’s body. The first results, published in Science by dozens of scientists from around the world, show the warm prospects for the future of mankind.
"This is basically very good news forspace flights and those interested in becoming astronauts, ”says Chris Mason, a professor at Cornell University, the principal investigator of twins. “Although the body is able to undergo an extraordinary amount of changes, it also demonstrates an extraordinary plasticity in returning to its normal earthly state.”
The study examined a number of biologicalmarkers, from the immune system (it functioned the same way as on Earth) to the shape of the eyeballs (consolidation of the optic nerve in Scott). But two of the most interesting results were obtained from the study of DNA and gene expression.
Susan Bailey and her colleagues at the State UniversityColorado focused on observing the length of the telomere Scott Kelly and the associated enzyme telomerase. Telomeres are located at the ends of the DNA and their length usually means age and health. Aging, stress and radiation reduce telomeres.
Because spaceflight exposes people likestress and radiation exposure, the researchers expected to see a reduction in telomeres. “But it was exactly the opposite,” says Bailey. “As soon as our earliest samples were taken in flight, about two weeks after the flight, we saw much longer telomeres from Scott than those that he had before departure.”
And this trend continued throughout Kelly's stay on the space station. In general, his telomeres lengthened by about 14.5%.
So what does this mean? Do not think that we suddenly found the source of youth in space. One week after his return, his telomeres were significantly reduced. “These are very, very specific to space flight changes, and they are very fast, and they made us think about what their cause might be,” says Bailey. The average length of Scott Kelly telomeres returned to normal after six months, but an abnormally large number of short telomeres, which were formed after his return to Earth, remained in his body.
The main mystery is why this happened. Data on telomerase, an enzyme associated with telomere length, was not obtained under ideal conditions: although the samples from Kelly's body in space came to scientists within 48 hours, the conditions on the way to the laboratory were not controlled well enough to prevent telomerase activity loss. The return to Earth in the capsule "Union" does not match the ideal laboratory conditions.
Another major change was found in the expression of the Scott Kelly genes, that is, in the way that DNA directs cells to produce components like proteins.
Scientists have seen how many genes are included andturned off during the flight, especially those that are associated with blood circulation and the immune system. These changes hint at how the body is trying to adjust to the cosmos.
Mason says that in the first half of the mission theysaw almost 1500 genes change their expression. In the second half of the mission there were six times more. This suggests that the human body changes in space gradually, and not just upon arrival.
Just like with telomeres, mostChanges in gene expression are fully addressed when Scott Kelly returns home. But several hundred genes seem to have memorized their time spent in space, and saved the changes.
Is it a lot or not - and what are the consequences forHealth is - we just do not know. We simply have nothing to compare. This is very similar to when people started measuring blood pressure for the first time. We simply did not know which numbers are the norm until we measured the pressure of a larger number of people.
At the same time, Scott Kelly says that ifafter landing, he was ill - as is usually the case - now he does not notice a big change in his state of health. “I feel different than when I started, but that’s probably because I’ve aged four years,” he says.
The next steps for the Bailey team will becreating the best testing methods to monitor telomerase activity, either on the ISS or on Earth. Mason is also studying technology that will eliminate the pressure on the sample during transport. His team even performed the first DNA sequencing on the ISS and hopes to improve this process. Most other scientists hope to get a wider sample size and, possibly, carry out longer tests. One astronaut is not enough to make final conclusions, so scientists such as Mason will study other astronauts during two-, six-month and one-year tests. Only these missions will not have twins on earth, with which it will be possible to compare.
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