Variation in whole-body regeneration between Botrylloides morphs and species

Abstract

Regeneration is a characteristic of the animal kingdom, and regenerative capacity is limited to higher taxonomical levels. In contrast, some basal animals like urochordates maintain a unique regeneration capacity, such as undergoing whole-body regeneration (WBR), an ability not observed in other chordates. Botryllids are colonial urochordates that can recreate new bodies through WBR from solely vascular tissue within ~2 weeks. To date, some species from the botryllid family were reported to orchestrate WBR, including B. diegensis. This study provided two novel records of WBR of B. jacksonianum and B. aff. anceps along with the two distinct morphs of B. diegensis. Interestingly, B. aff. anceps executed twin-body regeneration while this was limited to one-body for B. jacksonianum and B. diegensis. Histological sections validate the formation of multiple niches during WBR. Furthermore, the process of regeneration is phenotypically more similar between B. aff. anceps and B. diegensis. In contrast, the type of WBR in B. jacksonianum is similar to vascular budding as the niches were built from the vascular epithelium without undergoing significant tissue remodelling.