While the colonization of other planets is still out of reach, NASA scientists are investigating how long space can affect the human body. Detailed information is provided by an experiment with the participation of twins, one of whom spent a year in space, while the other remained on Earth.
Research with the participation of Marek and Scott Kelly is part of a larger scientific project, carried out by NASA (Human Research Program), during which researchers analyze to what changes in physiology, behavior, human microbiome and on the molecular level occurs in the human body under the influence of being in space. The experiment on twins has been going on since 2015. Men participating in it are 50 years old and both are professional astronauts and, most importantly, they are identical twins.
Jednjajowi = identical (but until time)
Monozygotic twins are natural clones, because they are formed as a result of the division of one egg cell and one sperm, and thus - they have the same genetic material. Therefore, they are initially indistinguishable. However, the number of differences between twins increases naturally over the years. Each of the twins carries their own baggage of experiences related to dietary habits, changes in the environment, stress or even the presence of a partner. Although their genes are still identical, their expression no longer.
At the beginning of genetics it was thought that our genes are our fate and the environment has a great impact on them. Today we know that it is not true. Currently, human DNA is treated as a kind of code for the production of proteins. In order for this code to be properly read, a manual is needed for it - because not all proteins are needed by the body at the same time. This instruction is epigenetic changes, including or excluding the action of specific genes depending on the ambient conditions.
Such epigenetic changes occurred during Scott Kelly's being in space.
Cosmos rejuvenate?
The first work, summarizing the results of Scott Kelly's annual stay at the International Space Station, was released a year ago. It showed that space flight is associated with a lot of stress for the human body. It is caused by a reduced amount of oxygen, inflammation and diametrical changes in nutrition. Stress, in turn, affects the change in gene expression and the length of telomeres (though not as expected).
Telomeres are the endings of chromosomes that protect genetic material during cell division from damage. However, each subsequent duplication of the cell is associated with a shortening of telomeres. So if someone is older, his telomeres are shorter. Researchers expected that staying in an environment as stressful as space would result in faster shortening of telomeres in a twin staying in space relative to a brother who remained on Earth. It turned out, however, that the year-long stay in outer space extended telomeres of Scott Kelly, so he "rejuvenated" him at the molecular level.
7 percent of changes
The recently published second paper presents the details of DNA changes in the "cosmic" twin. In general, the genetic material of Scott Kelly has not changed dramatically, no mutations in the genes. The change concerned only the expression of genes that help the body to cope with the new environment. This change involved 7 percent of genes, mainly related to the immune system, repair of genetic material, bone reconstruction, reaction to hypoxia and excess carbon dioxide. The remaining 93 percent of the DNA did not undergo any changes in expression or their expression returned to the "Earth standard" soon after returning to our planet.
Interestingly, returning to Earth was associated with a temporary decline in cognitive skills. Scientists explain it with the need to become accustomed to sunlight and gravity.
Based:
Human Research Program (NASA):https://www.nasa.gov/twins-study (access on April 20, 2018)
