UAS sequences regulate expression of Cas9::HN1HB1 in which the Cas9 sequence is human codon-optimized, GGSGP linkers are used at both the N-terminal and C-terminal ends of the Cas9 sequence to fuse it to the 'HN1' sequence and the 'HB1' sequence respectively, and with a Tag:NLS(SV40-largeT) tag at the C-terminal end of the Cas9::HN1HB1 coding sequence.