UASt regulates expression of a "mtDNA mutator" construct based on a mitochondrially-targeted cytidine deaminase, APOBEC1. The Rnor\Apobec1 cDNA is placed downstream of the mitochondrial targeting sequence of human ATP synthase subunit F1β (Tag:Mito(hATP5F1B)), a Tag:HA epitope and a flexible linker sequence 5'. A nuclear exporting sequence (NES) is inserted 3' to Rnor\Apobec1.