OPA1 and autosomal dominant optic atrophy: To assess the effect of parla KO on gene expression in the adult zebrafish brain, we determined expression of genes such as PTEN-induced kinase 1 (gene: pink1; protein: PINK1) and optic dominant atrophy (gene: opa1; protein: OPA1), both of which encode for mitochondrial proteins known to be PARL substrates [8,29].