3'-5' RNA exonuclease which cleaves in situ on specific transcripts in both nucleus and mitochondrion. Involved in regulating spatially segregated organellar RNA processing, acts as a coordinator of nucleo-mitochondrial crosstalk (PubMed:31081026). In nucleolus, processes pre-ribosomal RNA involved in ribosome assembly and alters cytoplasmic translation. In mitochondrial matrix, processes 3'-termini of the mito-ribosomal and messenger RNAs and controls translation of mitochondrial proteins (PubMed:31081026). Ubiquitously expressed, with highest levels in testis. Strongly up-regulated from 7 dpc to 11 dpc. Widely expressed at 8.5 dpc. At 11.75 dpc, expression is strongest in developing neuroepithelium and eye. Mutants are vital, fertile and display no gross abnormalities. They show an inconsistent pattern of altered anxiety-like behavior. Mutant males are significantly less anxious than their wild-type littermates, females show increased anxiety in the locomotor activity arena. Belongs to the MYG1 family.