Choanoflagellate Study Unveils Cellular Communication Predating Animal Evolution

A recent study published in Science Advances reveals the existence of electrical signaling and coordinated behavior in choanoflagellates, organisms considered the closest living relatives of animals. This research, conducted by the Burkhardt group at the University of Bergen's Michael Sars Centre, provides valuable insights into the early evolution of animal multicellularity and nervous systems.

The study focused on Salpingoeca rosetta, a choanoflagellate species that forms rosette-shaped colonies. Researchers discovered a surprising diversity of behaviors within these colonies, including communication among cells that regulates shape and ciliary beating.

First author Jeffrey Colgren expressed excitement about their findings, stating, "We didn't have clear expectations of what we would see in the cultures before putting them under the microscope, but when we did, it was very exciting."

Choanoflagellates, found in marine and aquatic environments worldwide, occupy a unique position between unicellularity and multicellularity. Some species, like S. rosetta, exhibit complex life cycles with colonial stages. While these colonies form through cell divisions similar to animal embryos, they lack specialized cell types and resemble a group of individual cells rather than a cohesive organism.

The research team developed a genetic tool to visualize calcium activity in S. rosetta, revealing that cells synchronize their behavior through voltage-gated calcium channels—the same type used by animal neurons and muscle cells. This discovery suggests that the ability to coordinate movement at the cellular level predates the first animals.

According to senior author Pawel Burkhardt, "Since our study reveals that colonial choanoflagellates coordinate their movements through shared signaling pathways, it offers fascinating insights into early sensory-motor systems."

The study opens up new avenues for research, with the team planning to investigate how signals propagate between cells and whether similar mechanisms exist in other choanoflagellate species. As Colgren noted, "The tools developed and findings from this study open up a lot of new and interesting questions. We're really excited to see where ourselves and others take this in the future."