Hierarchical roles of mitochondrial Papi and Zucchini in Bombyx germline piRNA biogenesis

The biogenesis of piRNAs in the silkworm Bombyx is simpler than in Drosophila, with the exonucleases Trim and Nbr having no major role, and the endonuclease Zuc acting at the 3′ rather than the 5′ end.