Biologists were able to identify the “archaea of Asgard” through microscopic examination. Reported by the University of Vienna.
All living organisms on earth are divided into three groups: eukaryotes, bacteria and archaea. Plants, animals and fungi are eukaryotes, they are distinguished by the presence of a cell nucleus. In 2015, genomic studies of deep-sea environmental samples found a group of so-called “Asgardian archaea.” On the evolutionary tree, they are closest to eukaryotes – that is, the closest relatives of nuclear organisms from another domain and the first representatives of multicellular life.
Austrian and Swiss scientists used an electron microscope to photograph cells subjected to shock freezing. “This method allows you to obtain a three-dimensional image of the internal cellular structures,” the authors explain. — Cells consist of round cell bodies with thin, sometimes very long processes. Sometimes these tentacle-like structures even seem to connect different cell bodies.” Cells also contain an extensive network of actin filaments (fibers) thought to be unique to eukaryotic cells.
Scientists have identified a model species from a number of such archaea, Lokiarchaeum ossiferum. Clusters of these organisms have a high density, which makes them easy to observe. Now scientists will focus on studying the bacterial symbioses of these archaea. The primitive eukaryotic cell is believed to have evolved from a close symbiosis between archaea and bacteria about two billion years ago. Thus, if successful, scientists will restore the history of the cell nucleus and the origin of multicellular life.