While the ability to regenerate lost body parts or organs is legendary in invertebrates like echinoderms, chordates-and mammals in particular-have quite limited regenerative ability. The exceptions par excellence are salamanders, which can regenerate lens, limbs and tails. Unfortunately, vertebrate models of regeneration are costly to maintain, suffer from necessary ethical considerations, and are often plagued by duplicated genes, hindering functional analyses. The invertebrate cephalochordate amphioxus is the most basal chordate. It is characterised by a prototypical genome, ancestral chordate morphology, and lacks the whole-genome duplications characteristic of vertebrates. With sequencing of the genome, it is therefore an excellent model for evolution of developmental mechanisms from an invertebrate ancestor. Until now, there has been no convincing evidence of regeneration in a cephalochordate. However, the candidate’s preliminary data indicate that amphioxus can regenerate all structures of the tail, including neural tube, notochord and muscle. The purpose of the proposed research is to develop the European amphioxus, Branchiostoma lanceolatum, as a new regeneration model. The ojectives are: 1. To characterise proliferation and stem cells during regeneration; 2. To evaluate whether the signalling pathways responsible for vertebrate regeneration are conserved in amphioxus, specifically TGFb and Wnt; 3. To determine whether matrix metalloproteinases are implicated downstream of these pathways during tissue remodelling; 4. To develop electroporation or explant culture methodologies to knock down gene function; 5. To assess the level of conservation of regeneration mechanisms in deuterostomes by comparing with echinoderms. The workplan will include bio-informatics, in situ hybridisation, immunohistochemistry, confocal microscopy and pharmacological treatments. This research may have implications for regenerative and stem cell therapy and tissue engineering.