Opening details

Although tardigrades cannot be seen with the naked eye, they live everywhere in the sea, in fresh water, on land, and even in the ice-covered Antarctica. They can also be found in radiation-contaminated areas as they can easily tolerate such conditions.

During past studies, it turned out that slow movement makes it possible to survive in conditions unbearable for other organisms. a unique gene sequenceSo scientists set out to decipher the genome of these magnificent creatures.

A team from Great Britain, Norway and Japan examined the genes responsible. Anhydrobiosis is a state of rest in which slow-moving animals fall, the body’s last supplies of water are preserved, and it becomes almost completely dry.. This allows them to shut down their metabolism until the situation around them becomes positive again, even if it takes decades. After that, they restart the metabolic process, replenish their moisture reserves and continue to live.

The genes that regulate this process are located in different parts of the cell, and a distinguishing feature of at least some tardigrade species is the presence of two sets of these genes at once. Also, like some other animals, they have a gene that provides resistance to stress.

To understand how such a genome was formed and where such creatures came from, scientists identified and examined the gene sequences of 13 tardigrade genera. The sample included representatives of two major classes of this species – Heterotardigrada and Eutardigrada.

They initially suggested that resistance to desiccation probably arose as an adaptation to terrestrial environments as tardigrades began to spread beyond marine waters. But in reality, they discovered a complex network of genetic connections in which some connections are duplicated in some species, while they are completely absent in others. At the same time, the effectiveness of anhydrobiosis does not always depend on the types and number of genes that should be associated with it.

The researchers left further “unraveling” of the genome to the future, but the information obtained was sufficient to reconstruct the main evolutionary chain of tardigrades.

• First of all, it was possible to confirm the hypothesis: the common ancestor of all slow-moving animals once really had to adapt to life outside the sea; some of its genes were later responsible for saving it from drought. This may have occurred during migration to freshwater bodies where water is also available, but unlike the sea there is also a risk of shallowing and drying out.
• Additionally, the analysis showed that different tardigrade species acquired some of these genes after diverging from a common ancestor. This is demonstrated by the different behavior of different gene clusters and different types of proteins; For example, when dried, they turn into granules in some places and thin threads in others. Thus, the formation of resistance to extremely dry conditions occurred in at least two stages.

What exactly do slow walkers do to survive?

In a new paper, a team of researchers say they have discovered at least one of the chemical switches that allow the body to enter anabiosis, also called “setting.”

A series of experiments found evidence that reactive oxygen species (ROS) play an important role in mediating the tuna process.

The researchers found that in tardigrades, ROS signals the oxidation of the amino acid cysteine, which is critical for tuna formation. When the team found a way to turn off the ability to oxidize cysteine ​​in tiny test subjects, the slugs instantly lost their tuning ability..

These particular conclusions are based on examining only a single species (Hypsibius exemplaris). And even as this study withstands further review by independent experts, the scientists understand that this is just the beginning of their work. The fact is that not all species of these creatures are sensitive to tuna; some late species use other survival strategies that have not yet been discovered.