Tardigrades Don't Survive Drying the Way We Thought

Thomas Boothby was a postdoc at UNC Chapel Hill in 2017 when he and his colleagues went looking for trehalose in tardigrades and couldn't find it. Trehalose is a disaccharide that brine shrimp, nematodes, and baker's yeast all pile up before they dry out — it stabilizes membranes and proteins as the water leaves. The textbook story said tardigrades did the same thing. The textbook story was based on almost no evidence; nobody had bothered to check carefully.

When Boothby's group checked, several tardigrade species had trehalose at trace levels or below detection, and the genome was missing the enzyme needed to make it. So the team ran a transcriptome under desiccation and asked what the animals were turning on. The answer was a family of intrinsically disordered proteins — chains so floppy they have no fixed shape — that the team called TDPs.

They vitrify. As water leaves the cell, the TDPs go from a solution to an amorphous, non-crystalline solid: a glass. That glass traps every fragile protein and membrane in place, frozen mid-fold, where nothing can unspool, aggregate, or shred. Disrupt the glassy state in the lab and the protection collapses with it.

The trick travels. Boothby's group put TDP genes into yeast and bacteria, dried them out, and the engineered cells survived desiccation that killed their wild cousins. Tardigrades evolved a different solution to the same problem brine shrimp solved with sugar — and theirs, smuggled into a yeast cell, still works.

Add water and the glass melts. The animal stretches, eats an alga, and walks off as if the last decade hadn't happened.