Drosophila melanogaster strain:multiple Targeted Locus (Loci)

Cytosine methylation in the genome of Drosophila melanogaster has been elusive and controversial: its location and function have not been established. We have used a novel and highly sensitive genome-wide cytosine methylation assay to detect and map genome methylation in Stage 5 Drosophila embryos. The methylation we observe with this method is highly localized and strand-asymmetrical, limited to regions covering ~1% of the genome, dynamic in early embryogenesis, and concentrated in specific 5-base sequence motifs that are CA- and CT-rich but depleted of guanine. The only known DNA methyltransferase in Drosophila is the DNMT2 homologue MT2, but lines deficient for MT2 retain genomic methylation, implying the presence of a novel methyltransferase. The association of methylation with lower expression of specific developmental genes at Stage 5 raises the possibility that it participates in controlling gene expression during the maternal-zygotic transition. This submission contains the validation data for the genomewide methylation map, obtained from bisulfite resequencing of 66 targeted regions from 6 wild type or MT2 mutant strains.