Ellen Phiddian
Cosmos science journalist
Nanometre-sized crystals more than 5km beneath the sea in the Mariana Trench hold hints about the origins of life, according to a team of Japanese researchers.
The self-organised nanostructures, which were found around hydrothermal vents, can act in ways that produce electricity.
The team has published its findings in Nature Communications.
Hydrothermal vents are jets of hot water, laden with dissolved minerals, which are formed when water seeps under the ocean floor and gets heated by magma.
They’re thought to be a place which might have heralded the beginnings of life on Earth, because of their heat, minerals, and stability.
This team of researchers examined samples collected from depths of 5,743m at the Shinkai Seep Field in the Mariana Trench in the Pacific Ocean.
They scanned the samples with optical microscopes and X-ray beams to learn more about its structure at the scale of micrometres and nanometres.
One sample – an 84cm piece of brucite – had columns of tiny brucite crystals which could act as channels for the fluid coming out of the hydrothermal vent.
These crystals carried an electric charge, but the charge varied between positivity and negativity across the surface.
This is important, because it’s an indicator of a process called “osmotic energy” conversion, which is a major feature of life.
Osmotic energy is created by a difference in concentration of salts in two liquids, separated by a membrane with small channels.
Living cells frequently rely on osmosis to get energy.
“Unexpectedly, we discovered that osmotic energy conversion, a vital function in modern plant, animal, and microbial life, can occur abiotically in a geological environment,” says lead researcher Dr Ryuhei Nakamura, from the RIKEN Center for Sustainable Resource Science and the Tokyo Institute of Technology, Japan.
The researchers tested the behaviour of the crystals by recording their voltage while exposed to different concentrations of salt.
The channels conducted differently depending on the concentration, in a similar manner to cells like neurons.
The researchers concluded that the crystals act like selective ion channels, allowing certain ions to flow through them depending on conditions. “The spontaneous formation of ion channels discovered in deep-sea hydrothermal vents has direct implications for the origin of life on Earth and beyond,” says Nakamura.
