Coordinated wound responses in a regenerative animal-algal holobiont

Many animals such as corals and sea slugs host photosynthetic symbionts. Several studies have investigated how the host and symbiont coordinate their activities. This new study by Sarfati et al. explores how symbiotic green algae and their animal host, the flattened-worm Convolutriloba longifissura, respond to injury. When the animal is injured, the algae’s photosynthetic efficiency drops, and the animal and algae show two waves of gene activity. Initially, the algae increase the activity of genes related to photosynthesis, although photosynthesis is not needed for regeneration. An important animal gene, runt, is activated after injury and is necessary for the animal’s regeneration. Decreasing runt expression alters the transcriptional responses in both the animal and algae and further decreases the photosynthesis by the algae after injury. This research shows that the host and symbionts are integrated at a molecular level and function as an integrated biological unit during regeneration. (Summary by Yueh Cho @YuehCho1984) Nature Comms. 10.1038/s41467-024-48366-2.