With a name meaning ‘slow stepper’, these eight-legged microorganisms might not sound very exciting. But tardigrades are arguably the toughest cookies in the animal kingdom and the most resilient creatures to have ever been discovered.
First described in 1773, these unassuming creatures, only up to a millimetre in length, have been found all over the world, from hot springs, to Mount Everest, to the freezing conditions of Antarctica. Not many other animals have been proven to survive a few minutes of exposure to temperatures of 151°C and equally ‘live to tell the tale’ after a quick freeze at -272°C (colder than the average temperature on the surface of Pluto). And talking of extra-terrestrial conditions, tardigrades can even survive the vacuum of space for 10 days, when we wouldn’t last 10 minutes.
But perhaps most incredibly, these little ‘water bears’ have been found to survive a decade of dehydration, where the levels of water in their bodies drop to from a healthy 85% to just 3%. It was previously thought that a sugar called trehalose, that is also found in some insects and plants, protects them from severe desiccation and allows revival within just an hour of contact with water. But a recent paper published in the journal Molecular Cell has shed light on proteins of a similar function that may be unique to tardigrades and allow them to be so extraordinarily resilient.
Thomas Boothby at the University of North Carolina and his co-authors described how “tardigrade-specific intrinsically disordered proteins”, or TDPs for short, allow the fluid in tardigrade cells to turn to a glass-like substance upon severe dehydration. This protects the more fragile parts of the cells from drying out and could have applications in other areas of science. The researchers proposed that the compounds could be used to produce drought-resistant crops or remove the need for cold chains in vaccine storage because the drugs could be stabilised instead. Not bad for a tiny little ‘moss piglet’.
For the nitty gritty on tardigrades and their adaptations, see the Boothby et al. (2017) paper: http://www.cell.com/molecular-cell/fulltext/S1097-2765(17)30133-8