Nanostructures in the deep ocean floor hint at life’s origin

a) Photograph of HV precipitates collected from the Shinkai Seep Field. b) Cross-polarized optical microscope images of precipitates in cross section. c,d) Scanning electron images showing layers within the precipitates. f) Magnification showing sublayers in the boxed area of d.
Credit: RIKEN

Researchers led by Ryuhei Nakamura at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan and The Earth-Life Science Institute (ELSI) of Tokyo Institute of Technology have discovered inorganic nanostructures surrounding deep-ocean hydrothermal vents that are strikingly similar to molecules that make life as we know it possible. These nanostructures are self-organized and act as selective ion channels, which create energy that can be harnessed in the form of electricity. Published Sep. 25 in Nature Communications, the findings impact not only our understanding of how life began, but can also be applied to industrial blue-energy harvesting.

When seawater seeps way down into the Earth through cracks in the ocean floor, it gets heated by magma, rises back up to the surface, and is released back into the ocean through fissures called hydrothermal vents. The rising hot water contains dissolved minerals gained from its time deep in the Earth, and when it meets the cool ocean water, chemical reactions force the mineral ions out of the water where they form solid structures around the vent called precipitates.

Hydrothermal vents are thought to be the birthplace of life on Earth because they provide the necessary conditions: they are stable, rich in minerals, and contain sources of energy. Much of life on Earth relies on osmotic energy, which is created by ion gradients—the difference in salt and proton concentration—between the inside and outside of living cells. The RIKEN CSRS researchers were studying serpentinite-hosted hydrothermal vents because this kind of vent has mineral precipitates with a very complex layered structure formed from metal oxides, hydroxides, and carbonates. “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 Nakamura.

The researchers were studying samples collected from the Shinkai Seep Field, located in the Pacific Ocean’s Mariana Trench at a depth of 5743 m. The key sample was an 84-cm piece composed mostly of brucite. Optical microscopes and scans with micrometer-sized X-ray beams revealed that brucite crystals were arranged in continuous columns that acted as nano-channels for the vent fluid. The researchers noticed that the surface of the precipitate was electrically charged, and that the size and direction of the charge—positive or negative—varied across the surface. Knowing that structured nanopores with variable charge are the hallmarks of osmotic energy conversion, they next tested whether osmotic energy conversion was indeed occurring naturally in the inorganic deep-sea rock.

The team used an electrode to record the current-voltage of the samples. When the samples were exposed to high concentrations of potassium chloride, the conductance was proportional to the salt concentration at the surface of the nanopores. But at lower concentrations, the conductance was constant, not proportional, and was determined by the local electrical charge of the precipitate’s surface. This charge-governed ion transport is very similar to voltage-gated ion channels observed in living cells like neurons.

By testing the samples with chemical gradients that exist in the deep ocean from where they were extracted, the researchers were able to show that the nanopores act as selective ion channels. At locations with carbonate adhered to the surface, the nanopores allowed positive sodium ions to flow through. However, at nanopores with calcium adhered to the surface, the pores only allowed negative chloride ions to pass through.

“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. “In particular, our study shows how osmotic energy conversion, a vital function in modern life, can occur abiotically in a geological environment.”

Industrial power plants use salinity gradients between seawater and river water to generate energy, a process called blue-energy harvesting. According to Nakamura, understanding how nanopore structure is spontaneously generated in the hydrothermal vents could help engineers devise better synthetic methods for generating electrical energy from osmotic conversion.

Journal: Nature Communications
DOI: 10.1038/s41467-024-52332-3

Media Contact

Adam Phillips
RIKEN
adam.phillips@riken.jp
Office: 81-048-462-1225 x2389

www.riken.jp

Media Contact

Adam Phillips
RIKEN

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

Targeting failure with new polymer technology to enhance sustainability

Sustainability is a complex problem with many different players and influenced by policies, society, and technical perspective. We are reminded every day in the media of the unnecessary amount of…

Solar-powered desalination system requires no extra batteries

Because it doesn’t need expensive energy storage for times without sunshine, the technology could provide communities with drinking water at low costs. MIT engineers have built a new desalination system that…

What we can learn from hungry yeast cells

EMBL Heidelberg and University of Virginia scientists have discovered a curious way in which cells adapt to starvation – a mechanism with potential cancer implications. What can stressed yeast teach…

Partners & Sponsors