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Scientists have reproduced in the laboratory how the ingredients
because life could have formed at the bottom of the ocean 4 billion years ago. The results of
the new study offers clues as to how life began on Earth and where else in the
cosmos we could find it.
Astrobiologist Laurie Barge and her team at NASA's Jet
Propulsion Laboratory in Pasadena, California, strives to recognize life on
other planets by studying the origins of life here on Earth. Their research
focuses on how the building blocks of life form in the hydrothermal vents on the
bottom of the ocean.
To recreate hydrothermal vents in the laboratory, the
team makes their own miniature seabed by filling goblets with
mixtures that mimic the primordial ocean of the Earth. These lab oceans act like
nurseries for amino acids, organic compounds essential to life, as we
know it. Like Lego blocks, amino acids build on each other to form proteins,
which make up all living things.
Hydrothermal vents are areas of the seabed where warm water from the earth's crust mingles with almost ice-cold seawater. These vents form natural chimneys, which host all kinds of ocean life.
Image credit: MARUM / University of Bremen / NOAA-Pacific Marine Environmental Laboratory
"Understand where you can go with just organic materials
and minerals before having a real cell is really important for
understand what types of environments life could emerge ", said
Barge, principal investigator and first author of the new study, published
in the journal Proceedings of the National Academy of Sciences. "Also,
study how things like the atmosphere, the ocean and the minerals of the
all impact vents this can help you understand how likely it is to have
occurred on another planet ".
Found around cracks in the seabed, hydrothermal vents are
places where natural chimneys form, releasing heated fluid under the earth's crust.
When these chimneys interact with the seawater surrounding them, they create a
ever-changing environment, necessary to the evolution of life and to the
change. This dark and hot environment powered by the Earth's chemical energy can be
the key to how life could form on more distant worlds in our solar system, far
from the heat of the sun
"If we have these hydrothermal vents here on Earth,
similar reactions could possibly occur on other planets, "said Erika from JPL
Flores, co-author of the new study.
Barge and Flores used ingredients commonly used at the beginning
The ocean of the Earth in their experiences. They combined water, minerals and the "precursor"
pyruvate and ammonia needed to start the formation of
amino acids. They tested their hypothesis by heating the solution to 158
degrees Fahrenheit (70 degrees Celsius) – the same temperature as found near a hydrothermal
wind – and adjusting the pH to mimic the alkaline environment. They too
removed the oxygen from the mix because, unlike today, the early Earth had very
little oxygen in his ocean. The team also used mineral iron
hydroxide, or "green
rust, "which was abundant on the primitive Earth.
Green rust reacted with small amounts of oxygen that the
team injected into the solution, producing the amino acid alanine and alpha
the hydroxyacid lactate. Alpha-hydroxy acids are byproducts of amino acids
reactions but some scientists think they could also combine to form
complex organic molecules that can lead to life.
"We have shown that in geological conditions similar to
Earth at first, and maybe at other planets, we can form amino acids and alpha
hydroxy acids from a simple reaction under mild conditions that would have
existed at the bottom of the sea, "said Barge.
Barge's creation of amino acids and alpha hydroxy acids in
The laboratory is the culmination of nine years of research on the origins of life.
Previous studies have examined whether the right ingredients
for life are found in the hydrothermal vents, and how much energy these mouths can
generate (enough to power a light bulb).
But this new study is the first time that his team is observing a very
similar to a hydrothermal vent cause an organic reaction. Barge and his team
will continue to study these reactions in anticipation of finding more
ingredients for life and the creation of more complex molecules. Step by step, she is
progressing slowly in the chain of life.
This area of research is important because scientists are studying
The worlds of our solar system and beyond can host habitable environments.
The moon of Jupiter Europa and
The moon of Saturn, Enceladus,
for example, the oceans may have hydrothermal vents beneath their icy crusts.
Understanding how life could begin in a sunless ocean would be helpful
scientists in the design of future exploration missions, as well as experiments
who could dig under the ice to look for evidence of amino acids or other biological substances.
molecules.
Future missions on Mars could return samples of the Red
The rusty surface of the planet can reveal traces of amino acids formed by iron.
minerals and old water. Exoplanets – worlds beyond our reach but always
in the field of our telescopes – can have life signatures in their
atmospheres that could be revealed in the future.
"We have not yet concrete evidence of life elsewhere"
said Barge. "But understand the conditions necessary for life
origin can help reduce places where we think life could exist. "
This research was funded by NASA Astrobiology
Institute, JPL team Icy Worlds.
For more information
on Astrobiology at NASA, please visit:
https://astrobiology.nasa.gov/
Media contact
Arielle Samuelson
Jet Propulsion Laboratory, Pasadena, California
818-354-0307
[email protected]
2019-030
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