Analysis of canonical A-to-I RNA editing in Drosophila using ICE-seq

The predominant form of RNA editing in animals is the enzymatic conversion of adenosine to inosine that is sequenced in cDNA as guanine. While RNA editing should be identifiable from RNA-seq data alone, genomic SNPs as well as sequencing and mapping errors result in a high false-positive rate. We used Inosine Chemical Erasing (ICE) with deep sequencing (ICE-seq) in order to validate A-to-I RNA editing genome-wide without the need for the sequencing of the underlying genomic DNA. We called RNA editing events in the head transcriptome of the reference strain of Drosophila melanogaster and six resequenced strains of Drosophila yakuba using the Illumina HiSeq and NextSeq platforms. We compared RNA editing sites reported in other studies and measured the level of conservation between D. melanogaster and D. yakuba. We found that while some of the best-studied editing sites in D. melanogaster are also edited in D. yakuba, we also detect a significant amount of species-specific editing in genes with different Gene Ontology enrichments, which suggests that the biological function of RNA editing in the two Drosophila species is diverging. Overall design: ICE-seq and RNA-seq pairs were generated for 6 strains of Drosophila yakuba and two replicates of Drosophila melanogaster. Two additional RNA-seq libraries were generated on the HiSeq and NextSeq.