title: Getting closer to a pre-vertebrate genome: the non-LTR retrotransposons of Branchiostoma floridae.
abstract: Non-LTR retrotransposons are common in vertebrate genomes and although present in invertebrates they appear at a much lower frequency. The cephalochordate amphioxus is the closest living relative to vertebrates and has been considered a good model for comparative analyses of genome expansions during vertebrate evolution. With the aim to assess the involvement of transposable elements in these events, we have analysed the non-LTR retrotransposons of Branchiostoma floridae. In silico searches have allowed to reconstruct non-LTR elements of six different clades (CR1, I, L1, L2, NeSL and RTE) and assess their structural features. According to the estimated copy number of these elements they account for less than 1% of the haploid genome, which reminds of the low abundance also encountered in the urochordate Ciona intestinalis. Amphioxus (B. floridae) and Ciona share a pre-vertebrate-like organization for the non-LTR retrotransposons (<150 copies, < 1% of the genome) versus the complexity associated to higher vertebrates (Homo sapiens >1.3.10(6) copies, > 20% of the genome).
authors.affiliation: Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Jon
authors.initials: J
authors.lastname: Permanyer
authors.forename: Ricard
authors.initials: R
authors.lastname: Albalat
authors.forename: Roser
authors.initials: R
authors.lastname: Gonzàlez-Duarte
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D043344:Chordata / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D018626:Retroelements / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D020079:Terminal Repeat Sequences / Q000235:genetics*
chemical_list: D018626:Retroelements