- Scientists recovered mud from more than 1.5 miles below the ocean surface
- The mud contained a single cell organism which could explain the origin of life
- It has been named Prometheoarchaeum syntrophicum after Prometheus
- Greek mythology claimed Prometheus stole fire from the gods and made man
Scientists have discovered a single-cell organism which could provide evidence about the origins of life on earth
Scientists used the deep submergence research vessel Shinkai 6500 to recover the mud
The Prometheoarchaeum syntrophicum, pictured, was scraped from the mud off the Japanese coast under 1.5 miles of water
A stock image showing prokaryotes. They were on Earth for two billion years before more complex life evolved
Single-celled flagellate Eukaryote Euglena under the microscope. They can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion
A microorganism scooped up in deep-sea mud off Japan’s coast is the missing link between ancient bacteria and the cells that led to humans, scientists claim.
A group of researchers from Japan studied the biology of the organism that was found 1.5 miles below the surface of the ocean by coaxing it to grow in a lab.
Life on Earth was originally made up of simple organisms such as bacteria and until this study, biology has had no answer for how more complex cells evolved.
Named Prometheoarchaeum syntrophicum, it was a stage between simple single cell organisms such as bacteria and the complex cells that led to animals and plants.
The name refers to the Greek mythological figure Prometheus who was said to have created humankind from clay and stole fire from the gods.
It is a spherical cell with a diameter of roughly 500 nanometers, or one-20,000th of a centimeter and boasts long, often branching tentacle-like appendages.
It is part of a group called archaea, relatively simple single-cell organisms lacking internal structures such as a nucleus – they are part of the prokaryotes group of cells.
Scientists have long puzzled over the evolutionary shift from such simple bacteria-like cells to more complex cells called eukaryotes.
The more complex cells allowed for the transition from the simple cells that first colonised the planet to complex cellular life include fungi, plants and animals.
To come up with their theory the team from Japan spent a decade getting Prometheoarchaeum to grow in a lab so they could observe it properly.
They also studied its relationship with a companion bacterium to find out if that had any bearing on the next stage of evolution into more complex cells with a nuclei.
The team say that the appendages on the new type of organism captured a passing bacteria, engulfed it and together they evolved into more complex cells.
They say it would have originally become mitochondrion – the powerhouse of a cell and crucial for respiration and energy production.
The solar system including Earth formed 4.5 billion years ago and the first life on Earth, simple marine microbes, appeared roughly 4 billion years ago.
The later advent of eukaryotes set in motion evolutionary paths that led to a riotous assemblage of organisms over the eons like palm trees, blue whales, T. rex, hummingbirds, clownfish, shiitake mushrooms and humans.
‘How we – as eukaryotes – originated is a fundamental question related to how we – as humans – came to be,’ said microbiologist Masaru Nobu.
Prometheoarchaeum is a member of a subgroup called Asgard archaea – named for the dwelling place of the gods in Norse mythology.
Other members of this subgroup were retrieved from the frigid seabed near a hydrothermal vent system called Loki’s Castle, named after a Norse mythological figure, between Greenland and Norway.
The research on Prometheoarchaeum, Nobu said, indicates that the Asgard archaea are the closest living relatives to the first eukaryotes.
The researchers used a submersible research vessel to collect mud containing Prometheoarchaeum from the Omine Ridge off Japan in 2006.
They studied it in the laboratory in a years-long process and watched it slowly proliferate after incubating the samples in a vessel infused with methane gas to simulate the deep-sea marine sediment environment in which it resides.
‘We were able to obtain the first complete genome of this group of archaea and conclusively show that these archaea possess many genes that had been thought to be only found in eukaryotes,’ Nobu said.
Prometheoarchaeum was found to be reliant on its companion bacterium.
‘The organism ‘eats’ amino acids through symbiosis with a partner,’ Nobu said.
‘This is because the organism can neither fully digest amino acids by itself, gain energy if any byproducts have accumulated, nor build its own cell without external help.’
Both Eukaryotes and Prokaryotes are cells – they are the fundamental building block that life is built from but they are very different.
Prokaryotes are simple celled organisms including bacteria and archaea without a distinct nucleus.
They are microscopic and likely the first type of life, evolving about 4 billion years ago on Earth.
It’s contents – the DNA, proteins and metabolites are all contained in a single cell membrane, rather than in separate compartments.
The name comes from the Greek for ‘before nucleus’ and were the only life on Earth for more than two billions years.
They usually reproduce through a process called binary fission where a single cell divides into two identical daughter cells.
These are organisms made of more complex cells and form the building blocks of everything from algae and plants to humans and mushrooms.
They are also microscopic but can be multicellular or single celled organisms.
They evolved on Earth about 1.5 billion years ago and contain a nucleus, separate compartments and mitochondria.
The mitochondria is the powerhouse of a cell and crucial for respiration and energy production.
The name comes from the Greek for ‘true nucleus’.
They can reproduce both asexually through mitosis and sexually through meiosis and gamete fusion.