Half caterpillar, half naked mole rat, the tardigrade does not look all that impressive. Yet this creature, also called a ‘water bear,’ is a true marvel of nature, since it displays pretty incredible resistance abilities. X-rays, extreme temperatures, empty space and even total dehydration pose no problem for this creature who can survive almost anything; some consider it to be almost indestructible.
To achieve this, this aquatic invertebrate measuring less than 1/8 of an inch long has developed remarkable defensive abilities. In particular is that of repairing its own DNA when it is damaged. Today, Japanese researchers think they have understood the origin of such a feat. By sequencing the tardigrade’s DNA, they discovered the existence of a very particular protein.
According to Takuma Hashimoto and his colleagues at Kyoto University, this protein is specific to tardigrades and protects its DNA from radiation damage. That's why scientists have dubbed it ‘Dsup’ for ‘damage suppressor.’
A protein transferred to human cells
‘We were quite surprised,’ said Takuma Hashimoto, a biologist and lead author of the study published in Nature Communications. For his research the team set their sights on a particular species of tardigrade, Ramazzottius varieornatus, considered to be one of the most resistant of them all. But they did not stop there.
To study its genome they inserted part of it into human cells, which they then exposed to radiation. This is how they discovered the origin of the animal's resistance, the Dsup protein. According to the results obtained, this addition to the DNA allowed any damage associated with the radiation of the cells to be reduced by 40%.
‘It's incredible that only one gene is enough to improve the radiation tolerance of human cells in a culture,’ commented Takuma Hashimoto to AFP. But the protein also protects the cells from desiccation, in other words extreme dehydration, a process that affects DNA in the same way as radiation does.
A future shield for human DNA?
‘X-ray tolerance is thought to be a result of the animal's adaptation to severe dehydration,’ said Takekazu Kunieda, a molecular biologist and member of the research team to Nature. Thus, the possibility that the tardigrade's abilities could be transferred to human cells continues to interest specialists.
‘We believe that the protein could function as a physical shield and protect human DNA from attack,’ said Takuma Hashimoto. This is all the more crucial since cells play a fundamental role in the protection and repair of DNA, and in the occurrence of certain diseases such as cancer.
This discovery could one day open up a way to improve the resistance of human cells or even ‘upend the way we preserve biological materials,’ according to Takekazu Kunieda. Nevertheless, the tardigrade is still far from having revealed all of the secrets behind its incredible resistance, as confirmed by another water bear expert.
According to Ingemar Jönsson, a scientist at Kristianstad University in Sweden, ‘we are just beginning to explore the genetic treasure that the tardigrade genome represents.’