Diversity of retrotransposable elements in compact pufferfish genomes

The compact genomes of the pufferfish species Takifugu rubripes (Fugu) and Tetraodon nigroviridis contain less copies but unexpectedly more clades of reverse transcriptase retrotransposons than the much larger human and mouse genomes. This retrotransposon diversity, also observed in zebrafish, is characteristic of fish genomes and was not lost after genome compaction in pufferfish species. The response of pufferfish genomes to retrotransposition appears similar to that observed in Drosophila melanogaster, which also presents an important turnover of retroelements.