UAS regulatory sequences drive expression of 'mtRosella' (PMID:24530295), which functions as a biosensor for the mitophagy process in vivo. The construct consists of Rosella (a pH-sensitive GFP fused to a RFP(Unk)) fused to a mitochondrial targeting sequence (Tag:Mito(Unk)); under normal conditions, the green and red signals overlap in mitochondria, whereas upon mitophagy mtRosella is transferred to the vacuole where the green signal is lost due to the acidic pH.