Genome-wide maps of R-loops in Drosophila embryogenesis and cultured cells

We report the genome localization of R-loops in early and late-stage embryos relative to Drosophila cultured cells. We demonstrate that proper absolute R-loop levels chage during embryogenesis and that resolution of R-loops is critical for embryonic development. R-loop mapping by strand-specific DRIP-seq revealed that R-loop localization is plastic across development, both in the genes which form R-loops and where they localize relative to gene bodies. Importantly, these changes are not driven by changes in the transcriptional program. Rather, negative GC skew and absolute changes in AT skew are associated with R-loop formation in Drosophila. Furthermore, we demonstrate that while some chromatin binding proteins and histone modification such as H3K27me3 are associated with R-loops throughout development, other chromatin factors associated with R-loops in a developmental specific manner. Examination of R-loops via ssDRIPseq in 2-3 hour embryos, 14-16 hour embryos, and S2 cultured cells.