Sep 6, 2021
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6 years in space did not damage the DNA of the sperm of mice

Researchers at Japan’s Yamanashi University found that “dried” sperm from mice that had been exposed to high levels of cosmic radiation for nearly six years gave birth to a large brood of healthy, unremarkable “space” mice. This achievement of scientists increases the chances of humanity for a successful colonization of space.

By the way, the sperm was stored at the International Space Station in a lyophilized, that is, dried, form. After returning to Earth and rehydrating (adding water) with its help, 168 cubs were born, which is surprising, devoid of any genetic defects.

The mice were born last fall, but all this time, scientists have been studying animals and comparing them with a control group of rodents. According to lead author of the study, Teruhiko Wakayama, there is little difference between mice fertilized with “space” sperm and sperm left over on our planet.

“All the puppies were of normal appearance,” said the biologist.

When researchers examined their genes, no abnormalities were found.

In 2013, Wakayama and his colleagues at Yamanashi University in Japan sent three containers to the ISS, each containing 48 ampoules of lyophilized semen for long-term research.

Scientists wanted to understand how long-term exposure to cosmic radiation will affect the DNA of germ cells, what will happen to reproductive cells and whether the resulting mutations will be passed on to offspring.

All this knowledge is important from the point of view of the future possible colonization of other planets by our species.

Cells rapidly accumulate mutations when exposed to radiation. As a result, tumors appear in the body or cells become nonviable. Photo: 8-cell embryos. / Photo by Teruhiko Wakayama / University of Yamanashi.

The reproductive cells were returned to Earth in batches for the fertilization of female eggs. This happened for the first time after nine months in space, then two years later, and finally six years later. Scientists eventually adopted hundreds of births in mice.

It also turned out that six years of “life” in orbit had an insignificant effect on the amount of damage in the genome of the repaired germ cells. There were about the same number of them as in the DNA of gametes that did not leave the Earth. In favor of this, in particular, was evidenced by a similar level of activity of enzymes that are responsible for correcting small mutations in the genome.

Why was the sperm pre-“dried”? This was necessary so that it could be stored at room temperature and not in the freezer. Still, when sending goods into orbit of roads (literally roads), every kilogram.

The sealed ampoules of the substance were also small and very light, about the size of a small pencil. This made it possible to further reduce the cost of launching an experiment into space.

When the “space” mice reached sexual maturity, they were randomly mated with other rodents. And the next generation also looked normal.

It turns out that cells resist radiation much better than scientists previously thought.

This gives rise to hope that long space travel and the colonization of nearby planets will not affect the ability of humans to continue their race in space.

All the details of the experiment can be found in the article by the authors of the study, published in Science Advances.

Yulia Rudy

Cover photo: This photo was taken on September 11, 2020. The offspring are healthy and active / Photo by Teruhiko Wakayama / University of Yamanashi.

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