The regulation of the life cycle of an amoeba could be the key to the origin of animal multicellular
The scientific study describes how the amoeba C. owczarzaki adopts different morphologies during its life cycle; one of them is an aggregative multicellular stage. This type of aggregative multicellularity has already been described in other eukaryotes—such as the amoeba Dictyostelium — that are animals’ close relatives. To be exact, Dictyostelium forms aggregates in response to some factors such as food scarcity.
Researchers have also studied C. owczarzaki gene expression in its different life cycle stages. Results show another scientific finding: the genes expressed during aggregation are also found in animals; they are relevant to form structures composed by several cells (tissues, etc.).
Iñaki Ruiz Trillo states that “the hypothesis of the study is that these genes, which play a key role in aggregate formation in amoebas, are the same that made possible to differentiate organisms with different type of tissues in animal morphology classification”.
The research also provides new evidence of the mechanisms that enable a gene to encode different proteins considering cell’s needs. According to authors, Capsaspora is a eukaryote, like plants and fungi, in which this process mostly generates non-functional proteins, but it is also a close relative of multicellular animals, which produce a wide range of functional proteins by means of this mechanism, and could resemble one of their earliest ancestors.
“This points out that, throughout evolution, the process of alternative splicing was a crucial factor in the origin of animals, as many new proteins were created from a single gene sequence”, explains Ruiz Trillo, who is also ICREA researcher at the Institute of Evolutionary Biology (CSIC-UPF). Researchers from the University of Toronto (Canada), Harvard University (United States) and the Massachusetts Institute of Technology (United States) collaborated in the research too.
Photo: Arnau Sebé-Pedrós