An article published in the journal “Nature Microbiology” describes a research on the mechanisms of cell size regulation in the three domains of life: archaea, bacteria and eukaryotes. In a previous research, a team led by Ariel Amir of Harvard University discovered that bacteria from the E. coli family and eukaryotes of the species Saccharomyces cerevisiae, commonly known as budding yeast, use the same cellular mechanisms to have uniform cell size in a population. Now, together with other collaborators, the team discovered that archaea use the same mechanisms as well.
The evolution of cells and the diversification in what were defined in recent years as the three domains of life are subjects in a full discussion phase. Archaea were recognized as organisms distinct from bacteria only starting from the 1970s and in the last decade a new classification was proposed that recognized them as a domain of life separated from bacteria, other single-celled organisms, and eukaryotes, formed by complex cells.
Among the problems that microbiologists have in the study of the evolution of archaea there’s the presence of characteristics of both bacteria and eukaryotes. A further difficulty is that archaea tend to be extremophile organisms, which means that they live in extreme environments that would be lethal for almost all the others such as volcanic sources at very high temperatures and/or very salty environments such as the Yellowstone springs. This makes it difficult to sample them and make them reproduce to study them and analyze their DNA.
The researchers studied archaea of the Halobacterium salinarum species, which lives in high-salinity environments. The comparison with E. coli bacteria and budding yeast showed that the the archaea controls cell size by adding a constant volume between two dividing events in the cell growth cycle.
The mechanism is not as precise in the archaea as it is in bacteria and eukaryotes and there’s more variability in cell division and growth than in bacteria’s cells. However, the basic mechanism is the same and Ariel Amir stated that this new research is the first to quantify the mechanisms of size regulation in archaea.
This discovery will allow researchers to better study these mechanisms and produce a model that explains the variability between key cell cycle properties. The ultimate goal is to understand why those mechanisms developed so commonly in the various domains of life.