The tardigrades are organisms capable of surviving very extreme conditions, such as toxic chemicals , and even radiation.
Tardigrades are also known as water bears and despite their small size (they do not reach a millimeter) they are almost indestructible and have reached the Moon.
Until now it was a mystery how they managed it, however, a new article published in the eLife magazine has managed to elucidate how they do it, in particular in the case of the species Ramazzottius varieornatus .
They commonly live in aquatic and semi-aquatic environments around the world such as deep seas, high altitudes, and even places with freezing temperatures . They also tolerate exposure to high amounts of ionizing radiation (which causes DNA mutations) and all kinds of toxic chemicals capable of killing any other living being.
Water bears require water to obtain oxygen through gas exchange. In dry conditions they can enter a state of cryptobiotic desiccation that can last for decades. They feed mainly on animal and plant cells.
How do tardigrades survive radiation?
It is well known that tardigrade cells are protected by a protein called Dsup, short for Damage Supression Protein (or in Spanish: damage suppression protein).
In addition, previous research has shown that adding this protein to human cells allows them to better tolerate dangerous levels of X-ray radiation without being damaged. But until now it was not known how it worked.
The study to which we refer has been carried out by the University of California, San Diego. Explain how they have used different biochemical analysis systems to find out what the activity of the Dsup protein is like.
The results showed that the protein binds to genetic material within each cell, forming a protective barrier around it that protects it from damage.
[box type = »info» align = »» class = »» width = »»] X-ray radiation can break down water molecules inside cells, forming very dangerous particles called hydroxyl radicals that damage DNA. These radicals can also appear when cells are exposed to toxic chemicals such as hydrogen peroxide. [/ Box]
This research has found that cells are immune to hydroxyl radicals thanks to the protective shield that this protein creates around genetic material . In particular, this protein binds to the nucleosome that protects chromatin from hydroxyl radicals. Not only in the species R. varieornatus has been discovered, but also in another species, Hypsibius exemplaris , an ortholog of this protein has been discovered that works in the same way.
To this discovery is added another very positive aspect. Surprisingly, a conserved region in Dsup proteins exhibits sequence similarity to the nucleosome binding domain of vertebrate HMGN proteins that is functionally important for nucleosome binding and hydroxyl radical protection.