LAUSR

Two novel techniques refine genome-wide mapping of R loops. The R loop is a nucleic acid ménage à trois in which RNA inserts between the two DNA strands, hybridizing with one and forcing the other to bulge out. Identifying the genomic location of R loops is important for understanding their function, but, current mapping methods offer limited resolution. Now, Samie Jaffrey’s group at Cornell University and Xiang-Dong Fu’s laboratory at the University of California, San Diego have generated the two most precise R-loopmapping techniques to date. The Jaffrey group modified the DNA– RNA immunoprecipitation sequencing (DRIP-seq) technique, based on antibodymediated capture of RNA–DNA hybrids from fragmented genomic DNA, followed by deep sequencing (Dumelie and Jaffrey, 2017). The resolution of DRIP-seq is limited by the size of immunoprecipitated DNA GENOMICS