In 2015 and 2016, NASA conducted a unique experiment on twin astronauts, where one was monitored while in space and the other was on the ground. Now, the first early results from this Twins Study have been revealed.
The experiment involved astronaut Scott Kelly and his brother Mark, a former astronaut. Scott spent a year on the International Space Station (ISS) between March 2015 and March 2016, while his brother Mark remained on Earth. During that time, tests were performed on each of them to compare genetic differences between the two.
One of the main reasons for doing the study was to see how long-term spaceflight affects the human body. Although we’ve had humans permanently in space for decades now, the exact physical and mental changes that take place still aren’t clear. Getting to the bottom of this will be crucial for future long-term missions, like trips to Mars.
The preliminary results were presented on January 26 in Galveston, Texas, at a NASA Human Research Program meeting. Researchers found that Scott’s telomeres grew longer than his brother’s, which was a surprise to the scientists.
“That is exactly the opposite of what we thought,” said Susan Bailey, a radiation biologist at Colorado State University in Fort Collins, reported Nature.
The length of Scott’s telomeres returned to normal quite quickly after he returned to Earth, for reasons unknown at the moment. A separate study, due to be completed in 2018, will investigate why this happened.
Changes were also spotted in the DNA of the twins. Specifically, Scott went through less DNA methylation, the process where molecules called methyl groups are added to DNA. This was less surprising than the telomeres finding, according to the researchers.
The first peer-reviewed papers from the Twins Study are not expected until later this year or next year. But it’s clear from these early findings that it should make for interesting reading.
Scott and Mark made perfect subjects for this experiment because they have the same DNA. This means scientists have had the rare opportunity to directly compare changes in Scott’s genes with changes in Mark’s over the same time period.
Scientists already know that living in a weightless environment for six months or less can have negative effects on the human body, like stretching your spine, shrinking your muscles, or messing up your sleep cycle. But the effects of long-term exposure to space are less well-known.
Researchers are still combing through the data after taking biological samples from each twin before, during, and after Scott’s space mission. It might be some time before the full results of the Twin Study are published due to the amount and the sensitivity of the information, some of which the twins may want to keep private, according to Nature.
Some of the most interesting results so far
Scott’s telomeres got longer, then shrunk back to normal. Scott’s telomeres, or the caps at the end of chromosomes, became longer than his brother’s while he was in space, but quickly returned to their normal length once he returned home.”That is exactly the opposite of what we thought,” Susan Bailey, a radiation biologist at Colorado State University in Fort Collins, told Nature. That’s because shorter telomeres are generally associated with getting older. Scientists are still studying what this means, but it could be linked to more exercise and eating fewer calories while in space, according to NASA.
Scott’s methylation levels decreased. The level of methylation, a process that can change the activity of a DNA segment without changing its sequence, decreased in Scott’s white blood cells during flight and increased in Mark half-way through the study. “These results could indicate genes that are more sensitive to a changing environment whether on Earth or in space,” according to NASA.
The twins hosted different gut bacteria. Scott and Mark hosted different gut bacteria, or the “bugs” that aid in digestion, throughout the year-long study. This was probably a result of their different diets and environments, NASA writes.
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,” according to NASA.