On Earth, life is possible by using the energy obtained by consuming food, and by using "cellular respiration", that is to say the oxygen supply and the release of carbon dioxide. In the seabed without heat or light, that's another story . American researchers have just demonstrated how certain organisms canthrive there according to a radically different logic from what we find on the surface.
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At the bottom of the ocean, the extreme conditions around hydrothermal vents are favorable for life
Can life thrive in the ocean floor, where there is neither light nor heat? That's the question posed by biogeoscientists Jeffrey Dick and Everett Shock of Arizona State University. In their work, published in the Journal of Geophysical Research: Biogeosciences, they demonstrated that certain specific hydrothermal environments, such as fissures and chimneys, can harbor communities of complex organisms .
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"Around hydrothermal vents on the ocean floor, hot fluids mix with extremely cold sea water" , explains Everett Shock. “These conditions create the chemical forces necessary for the life of the tiny organisms which evolve in this extreme environment.” Better, when the chimneys are composed of rocks which produce the most hydrogen (known as “ultramafic rocks”), “the biosynthesis of basic elements of cells, such as amino acids and sugars, is particularly favorable.” However, to form larger molecules, such as proteins, it is necessary a reaction known as "polymerization", which requires even more energy .
This specific biochemistry ofseabed could end up in the oceans of exoplanets
How is it possible to produce proteins in inhospitable seabeds? The researchers designed a model combining theory and field data to validate that it was possible to see them appear in this "mixing zone" between two extreme temperatures. This discovery "offers a new perspective on biochemistry but also on ecology, said Jeffrey Dick. She suggests that “certain groups of organisms are inherently more favored in specific hydrothermal environments.”
The next step for these researchers will be to apply their calculations to the whole tree of life in order to establish a stronger link between geochemistry and genome evolution. In other words, their work helps to understand the chemistry of the evolution of life, and will allow to extrapolate howorganisms can appear under the inhospitable oceans of other planets .
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Source: Arizona State University