Minuscule Microbe Societies: Harnessing Electricity for Collective Play

A recent study released in Science Advances presents findings of electrical signaling and cooperative behavior in choanoflagellates, the closest living relatives of animals. This intricate demonstration of cell interaction provides significant insights into the initial development of animal multicellularity and nervous systems.

Researchers from the Burkhardt group at the Michael SARS Centre, University of Bergen, discovered an astounding variety of behaviors among the rosette-shaped colonies of the choanoflagellate Salpingoeca rosetta—and these diminutive organisms presented even more unexpected findings.

“We observed communication occurring among the cells within the colonies, which modulates shape and ciliary movement throughout the rosette,” elucidates lead author Jeffrey Colgren. “We had no definite expectations regarding what we might observe in the cultures prior to examining them under the microscope, but it was incredibly thrilling when we did.”

Multicellularity is a hallmark trait of all animals, enabling distinct interaction with their surroundings by assimilating inputs from highly specialized cell types, like neurons and muscle cells. For choanoflagellates, flagellated organisms present in marine and freshwater habitats globally, the line separating uni- and multicellularity is less pronounced.

Certain species, such as S. rosetta, display intricate life cycles featuring colonial forms. Although the colonies develop through cell divisions, similar to the embryonic development of animals, they do not possess specialized cell types and are better likened to a collection of individual cells rather than a unified organism.

“S. rosetta serves as a compelling model for exploring the rise of multicellularity throughout animal evolution,” states final author Pawel Burkhardt. “Since our research indicates that colonial choanoflagellates synchronize their movements via shared signaling mechanisms, it provides intriguing insights into the early development of sensory-motor systems.”

Employing a newly established genetic tool that allows for the visualization of calcium activity in S. rosetta, the team discovered that the cells synchronize their actions through voltage-gated calcium channels, the identical type of channels utilized by animal neurons and muscle cells.

“This demonstration of intercellular communication within choanoflagellate colonies highlights cell-cell signaling at the threshold of multicellularity,” remarks Colgren. Remarkably, this finding implies that the capacity to coordinate movement at the cellular level existed before the first animals emerged.

Looking ahead, the team intends to delve deeper into how signals propagate between cells and whether comparable mechanisms are present in other choanoflagellate species. “The tools developed and discoveries from this investigation present numerous intriguing and novel inquiries,”

Colgren sums up, “We are truly eager to see how we and others will expand on this in the future.”