The Rapid Regenerative Response of a Model Sea Anemone Species Exaiptasia pallida Is Characterised by Tissue Plasticity and Highly Coordinated Cell Communication.

Regeneration of a limb or tissue can be achieved through multiple different pathways and mechanisms. The sea anemone Exaiptasia pallida has been observed to have excellent regenerative proficiency, but this has not yet been described transcriptionally. In this study, we examined the genetic expression changes during a regenerative timecourse and reported key genes involved in regeneration and wound healing. We found that the major response was an early (within the first 8 h) upregulation of genes involved in cellular movement and cell communication, which likely contribute to a high level of tissue plasticity resulting in the rapid regeneration response observed in this species. We find the immune system was only transcriptionally active in the first 8 h post-amputation and conclude, in accordance with previous literature, that the immune system and regeneration have an inverse relationship. Fifty-nine genes (3.8% of total) differentially expressed during regeneration were identified as having no orthologues in other species, indicating that regeneration in E. pallida may rely on the activation of species-specific novel genes. Additionally, taxonomically restricted novel genes, including species-specific novels, and highly conserved genes were identified throughout the regenerative timecourse, showing that both may work in concert to achieve complete regeneration.