Extended Data Fig. 2: Validation of transition mutagenesis scheme.

(A) Three blocks with suspected gain-of-binding events or mismatch between adjacent blocks overlapping the same predicted binding motif were tested using alternative mutagenesis scheme or targeted 2 bp mutations. In all cases, a result confirming gain-of-binding was obtained. (B) Unbiased testing using alternative mutagenesis schemes. Blocks were mutagenized using both a deterministic transition scheme (default for this study) and a GC-preserving transversion scheme, with selected blocks also mutagenized through random scrambling. Embryos positive for H11 insertion and presence of tandem insertions are displayed, except when indicated otherwise (see Methods for genotype definitions). White arrowheads indicate regions in which results of alternative mutagenesis mismatch those of transition mutagenesis (blocks marked with asterisk). See Supplementary Note 2 for details. Related to Fig. 1.