Of SINEs, LINEs and Leeches: Identification and Molecular Characterization of Transposable Elements in Leech Genomes

Mobile genetic elements constitute a major part of almost every eukaryotic genome, and several types of such elements have been classified based on size, genetic structure and transposition intermediate. The fast growing availability of whole genome sequences of species across the living world provides almost unlimited possibilities for in depth molecular analyses of all kind, including the search for mobile genetic elements in animal taxa that have not yet been in the focus of respective investigations. Leeches are such a group of so far neglected organisms. However, aim of the present study was not to provide a comprehensive survey, but to perform the first molecular description and characterization of selected mobile genetic elements (MGEs) in leeches. Representatives of three types of MGEs could be identified and characterized, namely short interspersed nuclear elements (SINEs), long interspersed nuclear elements (LINEs) and long terminal repeats (LTR)-retro-transposons. Some of the newly described elements display unique structural features compared to archetype elements of the respective groups.