New tardigrade discovery reveals secrets of radiation resistance

We know that the little one tardigrade is one of the toughest creatures on the planet, and a newly discovered species of these miniature “water bears” has given experts a deeper insight into how they can withstand harmful radiation.

When researchers from several institutions in China took a closer look at the genome of the new species – Hypsibius henanensis – discovered six years ago, found 14,701 protein-coding genes, of which 4,436 (30.2 percent) were unique to tardigrades.

They also exposed the little creatures to blasts of radiation, watching to see how gene expression and protein production would be affected – and kind of biological superpowers these genes could provide tardigrades.

“Studies on several tardigrade species have documented that these are the most radiation tolerant animals on Earth” write researchers in their published work.

“They show resistance to gamma radiation up to 3,000 to 5,000 grays (Gy), about 1,000 times the lethal dose for humans.”

The team made three key observations: a gene called DODA1potentially transferred from bacteria, produces pigments known as the betalainsand these help neutralize harmful molecules that are generated by radiation.

Second, DNA was being repaired much faster than normal, thanks to a tardigrade-specific protein called TRID1, and third, it increased the production of two other proteins, BCS1 and NDUFB8 (which help and energy supply).

While some of these tricks were already known, such as high-speed DNA repair, careful analysis of H. henanensis gives us more details on what exactly is going on – and how the humble tardigrade it remains so robust.

Combined together, these three processes that occur in response to radiation help protect tardigrades from its harmful effects. The next step is to see how generally these protective measures are applied across all tardigrade species.

“Whether the radiation tolerance of other tardigrade species occurs through conserved mechanisms or is specific to the genus Hypsibius requires further study.” write the researchers.

There are about 1,500 species of tardigrades that we know about, and the new study matches previous research in Hypsibius exemplaris tardigrades: when radiation is detected, the creatures turn on repair genes.

And these findings go far beyond the tardigrade. However small it is, the ways in which this animal can cling to life they are useful for figuring out how to better protect our own bodies in extreme environments (not least during long-duration spaceflight, for example).

Tardigrades are believed to have first appeared before the Cambrian, which is about 541 million years ago. To survive this long, you must have a lot of tricks at your disposal to stay alive.

“Tardigrades’ ability to survive in the harshest conditions continues to reshape our concept of the limits of animal life on Earth.” write the researchers.

The research was published in Science.

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