UAS regulatory sequences drive expression of four sgRNAs; two target Wnt6 (sgRNA sequences ATTTGGATCGAGAAGGATGTTGG and TGCCAATGACTGGATTCGGCTGG) and two target wntD (sgRNA sequences GTGTACTGGTAGTAGCTCATGGG and CATGGGTATTACGAGCACTCTGG). The sgRNAs are expressed as a single polycistronic tRNA-gRNA cassette.