Deep ocean crystals in hydrothermal vents reveal clues about origins of life

Amazing stuff!

"Researchers ... 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. ... the findings impact not only our understanding of how life began, but can also be applied to industrial blue-energy harvesting. ...

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 ... discovered that osmotic energy conversion, a vital function in modern plant, animal, and microbial life , can occur abiotically in a geological environment ...

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. ..."

From the abstract:

"Cells harvest energy from ionic gradients by selective ion transport across membranes, and the same principle is recently being used for osmotic power generation from salinity gradients at ocean-river interfaces. Common to these ionic gradient conversions is that they require intricate nanoscale structures. Here, we show that natural submarine serpentinite-hosted hydrothermal vent (HV) precipitates are capable of converting ionic gradients into electrochemical energy by selective transport of Na+, K+, H+, and Cl-. Layered hydroxide nanocrystals are aligned radially outwards from the HV fluid channels, constituting confined nanopores that span millimeters in the HV wall. The nanopores change the surface charge depending on adsorbed ions, allowing the mineral to function as a cation- and anion-selective ion transport membrane. Our findings indicate that chemical disequilibria originating from flow and concentration gradients in geologic environments generate confined nanospaces which enable the spontaneous establishment of osmotic energy conversion."

Deep ocean crystals reveal clues about origins of life

Nanostructures in the deep ocean floor hint at life's origin (original news release)

Nanostructures in the deep ocean floor hint at life’s origin (original news release by RIKEN)

Osmotic energy conversion in serpentinite-hosted deep-sea hydrothermal vents (open access)

Fig. 6: Osmotic power generation by selective ion transport in hydrothermal vent (HV) precipitates.

Crustaceans found to fertilize seaweed like bees pollinate plants

Amazing stuff! Animal-mediated pollination may have evolved first in water before on land.

"... via experiments and observations in the wild, the researchers discovered that the idoteas [marine isopods (small crustaceans)] play a helping hand. It was observed that as the crustaceans forage on male G. gracilis alga, sticky mucilage-coated spermatia (male gametes) cling to the animals' cuticles – the spermatia are produced by structures that dot the surface of the alga.

When those same idoteas land on a female alga, some of the spermatia are transferred to its reproductive organ, completing the fertilization process. The idoteas get something out of the deal too, as the algae provides protection from the elements, plus its surface is covered in small organisms which the iodteas eat. ..."

From the abstract:

"The long-held belief that animal-mediated pollination is absent in the sea has recently been contradicted in seagrasses, motivating investigations of other marine phyla. This is particularly relevant in red algae, in which female gametes are not liberated and male gametes are not flagellated. Using experiments with the isopod Idotea balthica and the red alga Gracilaria gracilis, we demonstrate that biotic interactions dramatically increase the fertilization success of the alga through animal transport of spermatia on their body. This discovery suggests that animal-mediated fertilization could have evolved independently in terrestrial and marine environments and raises the possibility of its emergence in the sea before plants moved ashore."

Crustaceans found to fertilize seaweed like bees pollinate plants

Pollinators of the sea: A discovery of animal-mediated fertilization in seaweed (no public access)