A recent study has uncovered significant evidence of electrical signaling and synchronized behavior in choanoflagellates, which are the closest living relatives of animals. This sophisticated instance of cell communication sheds light on the initial evolution of multicellularity in animals and the development of nervous systems.
A recent study published in Science Advances has uncovered significant evidence of electrical signaling and synchronized behavior in choanoflagellates, the closest living relatives of animals. This sophisticated instance of cell communication sheds light on the initial evolution of multicellularity in animals and the development of nervous systems.
Researchers from the Burkhardt group at the Michael Sars Centre, University of Bergen, discovered a fascinating variety of behaviors within the rosette-shaped colonies of the choanoflagellate Salpingoeca rosetta, revealing even more surprising findings about these small organisms. “We observed communication among the cells of the colonies that helps regulate their shape and ciliary beating across the rosette,” notes Jeffrey Colgren, the first author of the study. “We didn’t have specific expectations before examining the cultures under the microscope, but the results were very exciting.”
Multicellularity is a key feature of all animals, as it allows for unique interactions with the environment by integrating inputs from specialized cell types, such as neurons and muscle cells. In contrast, the boundary between unicellularity and multicellularity in choanoflagellates—flagellated organisms found in marine and freshwater habitats worldwide—is less clear. Some species, like S. rosetta, have complex life cycles that include colonial stages. Though colonies are formed through cell divisions similar to how animal embryos develop, they do not possess specialized cell types and resemble a collection of individual cells rather than a unified organism. “S. rosetta is an excellent model for exploring the rise of multicellularity during animal evolution,” explains Pawel Burkhardt, the last author. “Our findings that colonial choanoflagellates coordinate their movement through shared signaling pathways provide intriguing insights into the development of early sensory-motor systems.”
Employing a novel genetic tool that visualizes calcium activity in S. rosetta, the researchers discovered that the cells synchronize their activities through voltage-gated calcium channels, which are also found in animal neurons and muscle cells. “This evidence highlighting how information is transmitted between cells in choanoflagellate colonies represents cell-to-cell signaling at the brink of multicellularity,” Colgren states. Notably, this discovery implies that the capability for cellular coordination predates the existence of the first animals.
Looking ahead, the team intends to further explore how signals propagate among cells and investigate whether similar communication mechanisms are present in other choanoflagellate species. “The tools we developed and the findings from this study raise many intriguing questions,”
Colgren adds. “We are very excited to see where our work and that of others will lead us in the future.”
