Tardigrades tolerate extreme environments thanks to unique genes

Unique genes enable tardigrades to tolerate extreme environments

Their specific proteins help cells resist DNA damage

On September 20, the UK journal Nature Communications published a latest genetics research result on genome sequencing. The study discovered a gene in the tardigrade, a type of water bear, whose protein can resist deoxyribonucleic acid (DNA) damage in cultured human cells. This indicates that proteins unique to tardigrades will help cells resist DNA damage.

Tardigrades are the toughest known organisms on Earth, having gained fame for being able to survive in a vacuum. This small aquatic animal, whose scientific name is tardigrade, can survive in extreme pressure environments (including vacuum) without protective measures, or successfully revive after being frozen for more than 30 years. However, previously people did not understand how it managed to do this.

The peculiar abilities of tardigrades prompted researchers to investigate their genome. The first genome sequencing results showed that during the evolution of tardigrades, they acquired a large number of genes from other species through horizontal gene transfer (the transfer of DNA between the genomes of different species). However, the root cause of tardigrades' ability to withstand extreme environmental stress remained an unsolved mystery.

Takekazu Kunieda of the University of Tokyo in Japan and colleagues this time revealed a high-quality genome of the tardigrade known for tolerating high-pressure environments. They did not find evidence of large-scale horizontal gene transfer, but compared with flies and worms, the number of genes responsible for tolerating high-pressure environments was greater. In addition, they discovered a protein that binds to DNA and helps protect cultured human cells from X-ray radiation. Through detailed comparison of tardigrade genes with those of other species, the paper's authors found that the gene specifying the genetic code for this protective protein is unique to tardigrades.

These research results do not support the view that tolerance originates from horizontal gene transfer. Although it is still unclear how the unique adaptations of tardigrades function at the molecular level or organism level, the above research results indicate that tardigrades have evolved a unique "secret manual" for combating stressful conditions. (Reporter Zhang Mengran)