Opening a biologist from Russia has called into question the story of the evolution of multicellular

© Photo : press service of Megastructure cells and mitochondriaOpening a biologist from Russia has called into question the story of the evolution of multicellular© Photo : press service of Moscow state University

Biologists from Russia and foreign countries have opened extremely unusual single-celled organism that caused them to doubt the conventional ideas about the evolution of the most primitive ancestors of humans and other multicellular animals, according to a paper published in the journal Current Biology.

«Ancoracysta twista is a separate, previously unknown evolutionary line of the tree of life level of the Kingdom. It has a unique structure and form. We showed that mitochondrial genes have been lost many times independently in different groups of eukaryotes during their evolution, as opposed to a single large-scale loss of genes in the common ancestor of all organisms with a separate nucleus», — says Denis Tikhonenkov Institute for biology of inland waters Russian Academy of Sciences, quoted by the press service of the Russian science Foundation.

According to modern concepts, the eukaryotes — complex cells with a separate nucleus and a complete «set» of other organelles — was the result of «assimilation» of their ancestors of different bacteria and archaea. A typical example of this process are the mitochondria — the cellular «power plants» that synthesize the main «Energobalance» cells – the ATP molecule.

They are separated from the rest of the cell by a double membrane, like the shell of bacteria, and have their own DNA and protein synthesis. The organs of photosynthesis in plants and algae — chloroplasts — have a similar nature. «Domestication» of mitochondria, as biologists now believe, was a key step in the evolution of our single-celled ancestors.

Since mitochondria play a crucial role in cell life and humans and all other eukaryotes, many scientists today believe that this «domestication» was completed at the very first stages of the evolution of multicellular living beings, even before the split the ancestors of protozoa, animals, fungi and plants.

Tikhonenkov and his colleagues from Europe and America found out that it likely wasn’t, opening an unusual single-celled creatures, Ancoracysta twista, was found on the surface of one of the corals in the tropical seas of Earth, whose mitochondria are not similar to those of the cells of all other eukaryotes.

Study and comparison of the structure of about two hundred proteins, critical to the operation of the cells and therefore changing little in the course of evolution, showed that the creature has no close relatives of all modern eukaryotes. Moreover, it was found that its mitochondrial genome was «improperly» arranged for such primitive creatures, so close to the common ancestor of all organisms with a separate nucleus.

As the scientists explain, early evolutionists believed that most of the genes that control the development of the mitochondria-the «moved» into the DNA of future eukaryotic cell during a single process of transferring genetic material. Example Ancoracysta twista shows that this happened not once, in two or more stages, and that the last steps could occur in different ways the precursors of the various kingdoms of multicellular creatures.

According to the Tikhonenkov, in the seas and other parts of the world may hide other creatures with an equally unusual «ancestry», the study of which will help scientists to understand how really appeared the first multicellular creatures of the Earth and their protozoan relatives.