tailieunhanh - Báo cáo y học: "The role of transposable elements in the evolution of non-mammalian vertebrates and invertebrates"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: The role of transposable elements in the evolution of non-mammalian vertebrates and invertebrates. | Sela et al. Genome Biology 2010 11 R59 http 2010 11 6 R59 w Genome Biology RESEARCH _ Open Access The role of transposable elements in the evolution of non-mammalian vertebrates and invertebrates Noa Sela 1 2 Eddo Kim1 and Gil Ast 1 Abstract Background Transposable elements TEs have played an important role in the diversification and enrichment of mammalian transcriptomes through various mechanisms such as exonization and intronization the birth of new exons introns from previously intronic exonic sequences respectively and insertion into first and last exons. However no extensive analysis has compared the effects of TEs on the transcriptomes of mammals non-mammalian vertebrates and invertebrates. Results We analyzed the influence of TEs on the transcriptomes of five species three invertebrates and two nonmammalian vertebrates. Compared to previously analyzed mammals there were lower levels of TE introduction into introns significantly lower numbers of exonizations originating from TEs and a lower percentage of TE insertion within the first and last exons. Although the transcriptomes of vertebrates exhibit significant levels of exonization of TEs only anecdotal cases were found in invertebrates. In vertebrates as in mammals the exonized TEs are mostly alternatively spliced indicating that selective pressure maintains the original mRNA product generated from such genes. Conclusions Exonization of TEs is widespread in mammals less so in non-mammalian vertebrates and very low in invertebrates. We assume that the exonization process depends on the length of introns. Vertebrates unlike invertebrates are characterized by long introns and short internal exons. Our results suggest that there is a direct link between the length of introns and exonization of TEs and that this process became more prevalent following the appearance of mammals. Background Transposable elements TEs are mobile genetic sequences that comprise a large fraction of mammalian genomes