Many genes are turned off by chemical modifications (epigenetic marks) that prevent activation of the gene. One hypothesis is that mammals cannot activate a hair cell regeneration program after the first few postnatal days because the responsible genes have been epigenetically silenced. This project uses HRP data that looks at these epigenetic marks in the ear for every gene, both during early and late development. The investigators will use this analysis to find candidate promoter regions, which control gene activity. Candidate genetic sequences from the mouse experiments will then be tested in zebrafish. These experiments will allow us to better understand how key hair cell regeneration genes are controlled.