title: Achilles, a New Family of Transcriptionally Active Retrotransposons from the Olive Fruit Fly, with Y Chromosome Preferential Distribution.
abstract: Sex chromosomes have many unusual features relative to autosomes. The in depth exploration of their structure will improve our understanding of their origin and divergence (degeneration) as well as the evolution of genetic sex determination pathways which, most often are attributed to them. In Tephritids, the structure of Y chromosome, where the male-determining factor M is localized, is largely unexplored and limited data concerning its sequence content and evolution are available. In order to get insight into the structure and organization of the Y chromosome of the major olive insect pest, the olive fly Bactrocera oleae, we characterized sequences from a Pulse Field Gel Electrophoresis (PFGE)-isolated Y chromosome. Here, we report the discovery of the first olive fly LTR retrotransposon with increased presence on the Y chromosome. The element belongs to the BEL-Pao superfamily, however, its sequence comparison with the other members of the superfamily suggests that it constitutes a new family that we termed Achilles. Its ~7.5 kb sequence consists of the 5'LTR, the 5'non-coding sequence and the open reading frame (ORF), which encodes the polyprotein Gag-Pol. In situ hybridization to the B. oleae polytene chromosomes showed that Achilles is distributed in discrete bands dispersed on all five autosomes, in all centromeric regions and in the granular heterochromatic network corresponding to the mitotic sex chromosomes. The between sexes comparison revealed a variation in Achilles copy number, with male flies possessing 5-10 copies more than female (CI range: 18-38 and 12-33 copies respectively per genome). The examination of its transcriptional activity demonstrated the presence of at least one intact active copy in the genome, showing a differential level of expression between sexes as well as during embryonic development. The higher expression was detected in male germline tissues (testes). Moreover, the presence of Achilles-like elements in different species of the Tephritidae family suggests an ancient origin of this element.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Konstantina T
authors.initials: KT
authors.lastname: Tsoumani
authors.affiliation: Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece.
authors.forename: Elena
authors.initials: E
authors.lastname: Drosopoulou
authors.affiliation: Insect Molecular Genetics Group, IMBB, Vassilika Vouton, 71110 Heraklion, Crete, PO Box 1527, Greece; Department of Environmental and Natural Resources Management, University of Patras, Agrinio, Greece; Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria.
authors.forename: Kostas
authors.initials: K
authors.lastname: Bourtzis
authors.affiliation: Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece.
authors.forename: Aggeliki
authors.initials: A
authors.lastname: Gariou-Papalexiou
authors.affiliation: Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece.
authors.forename: Penelope
authors.initials: P
authors.lastname: Mavragani-Tsipidou
authors.affiliation: Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece.
authors.forename: Antigone
authors.initials: A
authors.lastname: Zacharopoulou
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Kostas D
authors.initials: KD
authors.lastname: Mathiopoulos
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057055:Aspartic Acid Proteases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D049750:Genome, Insect; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D018626:Retroelements; D033621:Tephritidae / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014998:Y Chromosome / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D018626:Retroelements; D057055:Aspartic Acid Proteases