An international team of researchers has just unraveled the mysteries of the resistance of a new species of tardigrade, tiny animals capable of surviving conditions that no other organism can endure. The scientists reported their work on October 25 by publishing it in the magazine Science. These microscopic creatures are present in almost all terrestrial and aquatic environments, and can withstand extreme situations: space vacuum, severe temperatures, high pressures, and even radiation. This incredible robustness is due to their willingness to enter a state of cryptobiosis, where their metabolism is almost at a standstill.

The discovery of the genetic secrets of this extraordinary resistance could find very promising applicationsparticularly for medicine and space exploration.

A microscopic superhero with a unique genetic heritage

In the Funiu Mountains of China’s Henan province, scientists have identified a previously unknown species of tardigradebaptized Hypsibius henanensis. Its genetic sequencing reveals an arsenal of 14,701 genes, nearly a third of which are specific to these “ water bears » as we like to call them.

Even more impressive, these creatures tolerate radiation doses a thousand times higher at the lethal threshold for the human species. Faced with radiation, these creatures deploy an extraordinary defense mechanism. Exposed to doses of 200 to 2,000 Gy (unit of measurement used in radiology to quantify the dose absorbed by a material exposed to ionizing radiation), an extremely high dose, these organisms simultaneously activate 2,801 specialized genes.

This genetic response triggers three lines of defense : repairing damaged DNA, maintaining cell division and strengthening immune responses. A real molecular armor which gives them this unique resistance in the animal kingdom.

Another species of tardigrade, similar to Hypsibius henanensis. © Robert Schuster / Science Photo Library

Advanced cellular machinery

To illustrate the extent of this cellular reorganization, Professor Bob Goldstein of the University of North Carolina evokes a telling metaphor: that of a factory which, in times of war, redirects all its production towards the military effort. At the heart of this defensive system, researchers have identified a previously unknown key player: the TRID gene.

The latter acts like a gene commander, recruiting specialized proteins to repair the most severe breaks in DNA. However, the most surprising discovery concerns the very origin of certain tardigrade genes. Between 0.5 and 3.1% of its genetic heritage comes from other organisms, mainly bacteria. An evolutionary “borrowing” which has proven particularly advantageous: it allows it to produce betalains, antioxidant pigments which neutralize up to 70% of cellular damage caused by radiation.

Revolutionary medical applications in perspective

The potential applications of this discovery are of course arousing enthusiasm in the scientific community. In the medical field, a first promising breakthrough has already been achieved: researchers have succeeded in improving the resistance of human cells to radiation by treating them with betalains from tardigrades. “ This discovery could improve the stress tolerance of human cells, benefiting patients undergoing radiotherapy », Underlines Dr. Lingqiang Zhang, co-author of the study.

The protective mechanisms of the tardigrade could notably rsolve the thorny problem of vaccine conservation. Understanding how the tardigrade protects its proteins and genetic material during these extreme periods could inspire new techniques to stabilize vaccines and thus extend their shelf life.

On the side of space exploration, these discoveries suggest new solutions for protect astronauts from cosmic radiation during long-duration missions. Like those planned to reach the planet Mars, for example.

The best is still ahead of us; the discovery of Hypsibius henanensis is only the first step in a vast scientific project. Of the 1,500 known species of tardigrades, only a handful have been studied in detail. Professor Nadja Møbjerg from the University of Copenhagen emphasizes the importance of extending this research to other species. Who knows what these little bear cubs are still hiding from us ?

  • Researchers have discovered a new species of tardigrade, Hypsibius henanensisendowed with exceptional resistance to radiation enabled by unique genetic mechanisms.
  • Scientists have identified the TRID gene, a key component of DNA repair, and the antioxidant betalains that reduce cell damage.
  • These discoveries could revolutionize medicine (improvement of cellular resistance in radiotherapy) and space exploration (protection against radiation).

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