The P{Harvester} transgene contains both a source of Cas9 (Spyo\Cas9nanos.cPa) and also a transcription unit in which a U6 promoter drives expression of two sgRNAs, 'gRNA#1' (sequence GTAGTACGATCATAACAACG) and 'gRNA#2' (sequence GTACATCCATACAGTACCAG), both of which have no target site in the wild-type D. melanogaster genome.