Identification of novel LTR retrotransposons in the genome of Aedes aegypti.

We have detected seventy-six novel LTR retrotransposons in the genome of the mosquito Aedes aegypti by a genome wide analysis using the LTR_STRUC program. We have performed a phylogenetic classification of these novel elements and a distribution analysis in the genome of A. aegypti. These mobile elements belong either to the Ty3/gypsy or to the Bel family of retrotransposons and were not annotated in the mosquito LTR retrotransposon database (TEfam). We have found that approximately 1.8% of the genome is occupied by these newly detected retrotransposons that are distributed predominantly in intergenic genomic sequences and introns. The potential role of retrotransposon insertions linked to host genes is described and discussed. We show that a retrotransposon family belonging to the Osvaldo lineage has peculiar structural features, and its presence is likely to be restricted to the A. aegypti and to the Culex pipiens quinquefasciatus genomes. Furthermore we show that the ninja-like group of elements lacks the Primer Binding Site (PBS) sequence necessary for the replication of retrotransposons. These results integrate the knowledge on the complicate genomic structure of an important disease vector.