UAS regulatory sequences (from the pWALIUM20 vector) drive expression of a short hairpin RNAi line that targets Orc4 (primer sequences are 5'-ctagcagtGCGATTCCTTCAACTTCGAGAtagttatattcaagcataTCTCGAAGTTGAAGGAATCGCgcg-3' and 5'-aattcgcGCGATTCCTTCAACTTCGAGAtatgcttgaatataactaTCTCGAAGTTGAAGGAATCGCactg-3').