Tiny superhero tardigrade's genome may explain how it is able to trick death

Tardigrades are one of nature's tiniest superheroes, surviving in the harshest regions on the globe. With an ability to trick death worthy of the best sci-fi stories, scientists believe that the miniature aquatic creatures could provide clues to protect humans against DNA damage.

A look into their genome has revealed that tardigrades have an especially high number of genes responsible for the tolerance of extreme environments. Among them, one gene codes for a protein that appears to bind to DNA in human cultured cells and to protect it from external stressors.

Ever since scientists began to study tardigrades – also known as water bears – they haven't ceased to be amazed by the species' extreme resilience to harsh conditions. Tardigrades have also fascinated them for their monstrous appearance.

With dagger-teeth, podgy faces and sharp claws, they could be a bit repulsive if only they were not so small. On average, the creatures measure 0.15 cm long, which means they can only be seen with a microscope.

Coming back from the dead

But tardigrades should not be underestimated because of their small size. In 2007, they made the headlines when some were sent to outer space without protection and came back to Earth mostly unharmed. They are also known to survive dehydration, despite being aquatic animals that need water to reproduce. While they show no sign of life outside water, they can "come back from the dead" and resume their activity if a drop of water is added.

To understand tardigrades' resilience to high pressure, extreme climate and radiation, scientists from the University of Tokyo have sequenced a high-quality genome from the tardigrade species R. variornatus and identified genes linked to resistance to harsh contexts. The study, published in the journal Nature Communications, shows that compared to flies and worms, there is an increase in tardigrades of genes responsible for the tolerance of stressful environments.

"Our analysis revealed a loss of gene pathways that promote stress damage, expansion of gene families related to ameliorating damage, and evolution and high expression of novel tardigrade-unique proteins", the scientists say.

In a second part to the study, one of these unique proteins was tested in human cultured cells. The researchers found out that it had the potential to protect DNA in the cells from damage caused by radiation. The protein binds to DNA and suppresses X-ray-induced DNA damage by 40%.

The results from this study suggest that tardigrades have evolved unique strategies to cope with stressful conditions and that there is an avenue for future research, in order to better protect humans from environmental stressors.