Research, Technology

The ancestor of all life on Earth may have been discovered - it is a microbe with a "skeleton"

Single-celled organisms such as ciliatesshoe, it is customary to call the simplest. However, in most species of modern organisms, including ciliates, the cell itself is a complex mechanism that can be represented as a production with many different workshops (organelles) that perform a variety of functions. But the first single-celled organisms on Earth (prokaryotes) were not so complex. These were exclusively bacteria and archaea, which did not have a nucleus or any membrane organelles. That is, the difference between the first unicellular and later ones (eukaryotes) is colossal. But how did eukaryotes arise from the most primitive microorganisms? This question can be answered by Asgardian microbes, a group of archaea that have been found in the waters of the Atlantic Ocean. They all have one unique feature that indicates that these microbes may be our ancestors.

This is what an Adgardian bacterium looks like, which could be the ancestor of all life on Earth

How life appeared on Earth

From prokaryotes, life could not develop andbecome what we see it. The fact is that all modern plants, animals, fungi and many other living organisms are eukaryotes. Therefore, even after billions of years, the Earth would probably be inhabited only by archaea and bacteria. However, this did not happen due to the fact that one ancient archaea was able to plant a bacterium inside itself.

The structure of eukaryotic cells is vastly different from the structure of archaea.

Subsequently, from this bacteriummitochondria, that is, organelles that produce energy more efficiently than bacteria and archaea. But how did the archaea manage to capture the bacterium and enclose it inside its membrane? This could only happen if the archaea could control the membrane, allowing it to actually surround the bacterium. However, no archaea on Earth have had such abilities... None, except for the recently discovered Asgardian ones, which include the Loki microbe, which we talked about earlier. Therefore, it is not difficult to guess what interest these microorganisms aroused among scientists.

Adgar microbes gave rise to modern life?

It must be said that the ability itselfwiggling the membrane is not surprising. It is found in eukaryotes. Actin, one of the main proteins of the cytoskeleton (the cell scaffold or skeleton located in the cytoplasm of a living cell), helps them in this. However, science was previously sure that only aukaryotes could have a cytoskeleton. But during the study of Asgardian microbes, scientists discovered they had genes for a protein resembling actin.

In addition, scientists have found othergenes that are also responsible for membrane movements that eukaryotes have and were previously thought to be unique. From this we can conclude that the Asgardian microbe, if it really is the ancestor of eukaryotes, inherited these genes from them.

Adgar microbes contain a cytoskeleton (orange) that allows them to move their membrane

Ancient Archaea May Control Membrane

The presence of certain genes is not yetproof that the above theory is correct. Moreover, the ability of Asgardian microbes to move the membrane also does not prove the ability to control it like eukaryotes. The only way to get evidence is to see it with your own eyes through a microscope. This is exactly what scientists at the University of Vienna decided to do together with colleagues from Germany and Switzerland.

Did you know that, according to Moore's law, life on our planet is older than the Earth itself? You can read more about Moore's Law here.

To conduct research on Adgar microbes,scientists needed to grow them in large numbers. It turned out that this is not an easy task, which took about six years. But in the end, they were able to propagate the Loki microorganism (Lokiarchaeum ossiferum) and study it with an electron microscope. As it turned out, the time was well spent. The team was indeed able to see cytoskeletal structures in mobile membranes. This suggests that microbes are able to control membrane movements like eukaryotes. The authors of the work reported this in the journal Nature.

"Tentacles" of the Adgar microbe under a microscope

In addition, scientists have found “tentacles” in archaea,departing from the body. They may be evidence that an ancient microbe was able to grab a bacterium and stick it into its cell body. True, in order to draw final conclusions, scientists will have to conduct many other studies that they are already working on.

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But, in any case, the discovery made hasof great scientific importance, as it showed that genes previously thought to be unique to eukaryotes may also be present in archaea. True, not all, but only one species.