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A  study explains why astronauts age more rapidly in space



A new study has discovered another risk for astronauts: DNA replication is more prone to errors in microgravity, which has long been known to be a result of radiation exposure.


While flying in a parabolic flight pattern, the researchers tested whether enzymes could accurately copy DNA in cells while in microgravity, which is created by the weightlessness created by the jet. In nearly weightless conditions, the so-called "vomit comet" descends more than two miles in twenty seconds, resembling the conditions of space travel on Earth. It is critical for astronauts and the future of space travel that accurate DNA replication takes place in space.


"DNA polymerases are enzymes that are essential for the replication and repair of DNA. They are, of course, not without flaws: even under ideal circumstances, they can make mistakes from time to time. We demonstrate that DNA polymerases derived from the bacterium E. coli are significantly more prone to errors in microgravity environments such as those found in space than they are in normal gravity environments "According to the University of Toronto's corresponding author, Aaron Rosenstein. The findings of the study were published in the journal Frontiers in Cell and Developmental Biology.


The fact that DNA undergoes a higher rate of mutation when exposed to cosmic rays and solar particles is well known to scientists. The effects of space radiation on DNA can include single nucleotide substitutions, crosslinks, inversions, and deletions. These changes increase the risk of cancer, genetic defects in an unborn child and future offspring, tissue degeneration, and cataracts, among other things.


It was previously unknown whether or not weightlessness has an effect on the replication of human DNA. Due to a lower accuracy of DNA polymerase copies, a high mutation rate increases with each copy of the DNA, resulting in an increased incidence of cancer. Cosmological radiation causes cell damage and the onset of age-related diseases, according to research published in 2020 by scientists at the University of Rome, Tor Vergata (URV).


The authors of the new study demonstrated for the first time that the error rate of DNA polymerases in E. coli bacteria increases when the bacteria is suspended in space. They used a semiautomatic mini-laboratory to observe a single round of replication of a 1000-nucleotide-long DNA fragment while a jet flew parabolically above them, simulating space flight conditions, and recorded the results.


In flight conditions ranging from weightlessness to hypergravity, or twice the gravity at the Earth's surface, the scientists encountered difficulties operating their mini-laboratory equipment.


DNA Replication Deficiency Is a Potential Health Hazard


Astronauts on future moon and Mars missions may face health risks as a result of the combined effects of cosmic radiation and inaccuracy in DNA replication while in weightlessness, according to the authors' findings. Researchers stressed the importance of future spaceships generating artificial gravity to keep astronauts from suffering negative health consequences while in deep space.


"We have demonstrated that DNA polymerases similar to those found in mitochondria — the cell's powerhouses — make more errors in microgravity," said co-author Virginia Walker of Queens University in Ontario, Canada. "This is the first time anyone has demonstrated this." It is possible that astronauts will experience premature aging as a result of the combined effect of increased damage and decreased replication accuracy.

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