A possible mechanism for the emergence of multicellularity has been discovered
PNAS: early multicellular animals evolved from chemical signals
Scientists at Indiana University Bloomington ( USA ) have found that the earliest animal likely used chemical signals to turn from a unicellular to a multicellular organism. This is reported in an article published in the journal Proceedings of the National Academy of Sciences (PNAS).
Biologists have studied philasteria, a single-celled eukaryotic organism Capsaspora owczarzaki that lives in snails and is able to form multicellular aggregates by releasing unknown signaling substances. During the experiment, the scientists cultivated microorganisms in a liquid medium, removing or adding components to determine which ones affect cell adhesion. It turned out that multicellular aggregation is regulated by calcium ions and lipids, with a decrease in the level of which the cells began to detach from each other.
As the authors write, the discovery shows that chemically regulated aggregation is important for various members of eukaryotic microorganisms. Therefore, this phenotype was likely an integral part of the life cycles of the single-celled animal ancestors.
Cell aggregation is also characteristic of other primitive animals, which exhibit it during the fundamental processes of development and maintenance of healthy multicellular tissues. Cells of sponges, cnidarians, and even vertebrates can disaggregate and reaggregate during embryonic development, during inflammatory processes, and for tissue regeneration.