História evolutiva de elementos transponíveis da superfamília Tc1-Mariner em drosofilídeos

Abstract

Transposable elements (TEs) are DNA regions that can move within and between genomes, causing great impact on the host organisms. The Tc1-Mariner superfamily stands out for being, probably, the DNA transposons superfamily with greater distribution in nature, being ubiquitous in eukaryotes. In part of this work, we characterize elements of the mariner family in Neotropical drosophilids, which were obtained through amplification with degenerated primers. The primers were designed for the catalytic domain region of mariner transposase allowing amplification of a wide range of mariner-like sequences. A sum of twenty-three species have mariner-like sequences belonging to three subfamilies (mellifera, mauritiana and irritans). These elements present a patchy distribution and incongruences with the host phylogeny, suggesting horizontal transmission events between drosophilids and even between drosophilids and species of other families, subfamilies and orders. Moreover, some sequences present open reading frames, conserved catalytic motifs and evidence for the action of a strong purifying selection, which suggest yhat they originated from active elements. In another part of the work, we characterize Paris-like elements (belonging to Tc1 family), through searches in the twelve Drosophila genomes available. These searches, enabled us to find five new Paris-like elements (one in D. ananassae, one in D. pseudoobscura, one in D. persimilis, one in D. mojavensis and one in D. willistoni), with a copy number ranging from two to seven. Three species have putatively active elements. The evolutionary analysis of these elements suggests that they have envolved through vertical transmission associated with some events of stochastic loss in the analysed species.