Regeneration ability appears to inversely correlate with body and tissue complexity, consequently, adult stem cells in human organs can act to repair damage but have a limited ability to fully restore structure and function. A striking exception to this relationship is the invertebrate colonial tunicate Botrylloides leachii. Colonies consist of adults (zooids) sharing a common vascular system embedded in a gelatinous matrix (tunic). Minute fragments of this vasculature containing only a few hundred cells are capable of regenerating a whole functional adult organism within 8 days.
Successful whole body regeneration (WBR) requires either a long-lived cell population of pluripotent stem cells and/or cells to undergo dedifferentiation process. The two main theories are that they either arise from a small circulatory population of pluri- or multi-potent cells, or there is a ‘stem cell’ niche within the vascular lining that becomes activated when regeneration is induced.
This project aims to identify genes that are likely to play stemness roles B. leachii WBR and examine their expression pattern during WBR. We have recently sequenced the B. leachii genome and transcriptome providing a resource to identify conserved pluripotency genes for further studies. tBlastn searches of the assembled B. leachii genome will be done to identify orthologues of such genes as Sox2, PIWI, Wnt and Foxd3. Expression of putative stemness genes will be quantified using RT-qPCR across 5 stages of WBR. To determine the cell types express these pluripotency factors, in situ hybridisation on B. leachii regeneration fragments will be carried out.