This project will reveal critical cell fate controlling mechanisms and understand how these mechanisms regulate limb regeneration processes in the aquatic salamander through the temporal suspension of cell identity of cells in the stump. How this temporal suspension is regulated at the molecular level is not well understood but recent progress in the development of genetic tools has made this question experimentally tractable. The project will focus on small RNAs. Methodologically, the work will involve determining the microRNAs (miRNAs) that are regulated during the different stages of limb regeneration. This will be followed by predicting the genetic targets of the miRNAs which expression has been found to be fundamental for successful limb regeneration. This will involve predicting putative binding sites of the miRNAs by looking at sequence complementarity between their 3´ untranslated regions (UTRs) and mRNAs present in the cell at a particular cell stage. Furthermore, this project will also study chromosomal accessibility at the different stages of limb regeneration and how it changes during this process. This will involve studying gene clusters that undergo changes in accessibility as well as what are the molecular regulators involved in this process. The genes found in these regulated areas can then be further studied by looking at their sequence and function.