UAS regulatory sequences drive expression of 4 sgRNAs (CCGCTGATGCCGAAGGTGTATGG, TTATCTATATATCCGCCGTGCGG, TCCGACGAGGGTAAAATGTACGG and CCGTGGACACCAGTGAATGCCGG), each of which targets sd. The sgRNAs are expressed as a single polycistronic tRNA-gRNA cassette.