A groundbreaking study published in Science Advances reveals that choanoflagellates, the closest living relatives of animals, demonstrate complex electrical signaling and coordinated behavior. Conducted by researchers at the Michael Sars Centre, University of Bergen, this research sheds light on the early evolution of multicellularity and nervous systems.
The team observed diverse behaviors within the rosette-shaped colonies of the choanoflagellate Salpingoeca rosetta. First author Jeffrey Colgren remarked, "We found communication among the cells of the colonies, which regulates shape and ciliary beating across the rosette." The findings were unexpected and thrilling, highlighting the sophisticated interactions among these small organisms.
Multicellularity is a defining trait of animals, allowing for intricate interactions with the environment. Choanoflagellates, which thrive in marine and aquatic ecosystems, blur the lines between unicellular and multicellular life. Some species, including S. rosetta, exhibit complex life cycles that resemble early animal development. Last author Pawel Burkhardt noted, "S. rosetta is a powerful model for investigating the emergence of multicellularity during animal evolution." The study indicates that colonial choanoflagellates utilize shared signaling pathways to coordinate movement, offering insights into the origins of sensory-motor systems.
Employing a novel genetic tool to visualize calcium activity in S. rosetta, the researchers discovered that cells synchronize their actions via voltage-gated calcium channels, similar to those found in animal neurons. Colgren stated, "This evidence of how information flows between cells in choanoflagellate colonies demonstrates cell-cell signaling at the cusp of multicellularity." This suggests that the capacity for cellular coordination may have emerged prior to the first animals.
Looking ahead, the research team aims to explore how signals propagate between cells and investigate whether analogous mechanisms exist in other choanoflagellate species. Colgren expressed enthusiasm for future inquiries, stating, "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."