Structure and Diversity of Tc1/mariner DNA Transposons in the Genome of the Jellyfish Aurelia aurita

Transposable elements (DNA transposons and retrotransposons) are DNA sequences that have the ability to change their position within a genome. They are suggested to play one of the key roles in adaptive and evolutionary processes. One of the most studied groups of DNA transposons is the ITm infraclass and, in particular, the Tc1/mariner superfamily. In the present study, the abundance, structure, and evolution of the Tc1/mariner DNA transposons in the jellyfish Aurelia aurita was examined. It was demonstrated that in jellyfish, the predominant proportion of Tc1/mariner elements was represented by the TLE family. A new subfamily of TLE elements (termed Aurum) was identified. In addition, in the Visitor family, two groups of elements, VS-aura and VS-beplau, were identified, which were probably separate subfamilies. Analysis of the structure and diversity of Tc1/mariner elements shows that Tc1/mariner transposons in the jellyfish genome are currently at the stage of degradation and elimination. Almost all elements are deleted or have structural changes and, accordingly, do not have potentially functional copies.