Caracterização e análise evolutiva de elementos transponíveis presentes no genoma de leptopilina boulardi

Abstract

Transposable elements, or mobile segments of genetic material, were discovered in maize (Zea mays) by Barbara McClintock in the 1940s and later featured in two major groups based on their transposition systems. Since then elements have been described in a wide variety of eukaryotes. With the development of sequencing techniques, it was recently identified that these elements may constitute a large part of the genome of various organisms, reaching 50% of the genome in primates and 85% of maize genome, and crucial for the growth of organisms acting for example, in the development of the immune system and the recognition of chromosomes. These changes caused by transposable elements are generally associated with mobilization processes. Horizontal Transfer phenomena of genes are essential for maintenance of TEs culminating in its invasion of new genomes. A major problem when studying transposition mechanisms is to mimic an ecosystem in the laboratory and when this is solved, comes the high cost of sequencing the genomes of various organisms. Thus this study aims to standardize a bioinformatic pipeline that allows the use of sequences from next-generation sequencing (NGS) with low coverage along with the characterization of the elements present in the genome of a wasp parasitoid drosophilid (Leptopilina boulardi) and the relationship of these elements with other organisms elements. Next generation sequencing Illumina Solexa-Hiseq 2000 was performed using 20 individuals of the specie L. boulardi, generating multiple reads of low coverage with an approximate size of 100 base pairs, which were subjected to various bioinformatics tools resulting in clusters (groups multiple reads) which were assembled in contigs (overlapping sequences defined by multiple reads), a portion of these showed homology with elements of TE’s database then representing 5.19% of wasp genome belonging to 15 different elements superfamilies. An analysis of the elements described in the literature was performed, with the wasp sequences and literature sequences were used some softwares for alignment, best amino acid substitution model and mounting the phylogenetic tree. 11 trees of different elements superfamilies that presented proteins domains described in the literature as belonging to the structure of these elements were construted. 26 taxa of elements described in the literature and 52 not yet described were characterized, which may indicate a new taxa of TEs, besides possible HTT processes between wasps and ants were identified. The pipeline built in this study was efficient when analyzing the quality of the threads and the high value of branch support present in phylogenetic trees, indicating the effectiveness of the methodology used, which allows an economy in lines of research using the simultaneous sequencing of various organisms.