Nanopore sequencing for mapping of retrotransposon integration sites in the Dictyostelium discoideum genome

The unicellular eukaryote Dictyostelium discoideum has a gene-dense haploid genome. This configuration presents mobile elements with the particular challenge of replicating without causing excessive damage to the host through insertional mutagenesis or recombination between repetitive sequences. D. discoideum harbors an active population of the retrotransposon TRE5-A that integrates in a narrow window of ~50 bp upstream of tRNA genes. We assume that this integration preference was developed to avoid the disruption of protein-coding genes. Therefore, we recently mapped new integrations of a genetically tagged TRE5-A element at tRNA genes using PCR-based enrichment of integration junctions. However, the PCR-based enrichment produced several artificial DNA fusions that prevented the mapping of integration sites in unknown places of the genome. Here, we reanalyzed the previous experiment using nanopore sequencing. We summarize the advantages and limitations of direct genome resequencing for the mapping of mobile element integrations.