IDENTIFICATION AND CHACTERIZATION OF RETROTRANSPOSABLE ELEMENTS Rex FAMILY IN GENOME SPECIES OF THE Leporinus GENUS SPIX, 1829 (TELEOSTEI: ANOSTOMIDAE)

Abstract

In the eukaryotes' genome there are two types of sequences, simple and repetitive. The repetitive sequences (repetitive DNA) are composed by individual sequences repeated several times. This special kind of DNA was in the past considered as "junk DNA" or "selfish DNA", but in recent years studies have been demonstrating that these sequences can be very important for the maintenance of the genome, being involved in various mechanisms of rearrangement and genetic material propagation. Within the group of repetitive DNA sequences are repeated in the chain, such as satellite DNAs, minisatellites and microsatellites, and dispersed in the genome sequences, which are called transposons and retrotransposons. There are many papers about the mechanisms of action and evolution of retrotransposable elements, such as the elements of the Rex family, which include sequences Rex1, Rex3 and Rex6. Such sequences appear to be widely distributed in the vertebrates' genome and phylogenetic analysis indicates that these sequences were often active in the evolution of various groups. Among these groups, the fish are noted for having many families of retrotransposons, so that most of these families are not found in other vertebrates, which makes this group an important model for studying the impact of the retroelements in vertebrate genome. This project aims to identify and analyze sequences of Rex1, Rex3 and Rex6 in species of the Leporinus genus, in order to know the organization, the variation among the species, the chromosomal distribution and understanding the evolution of these sequences in the genome of genus and in fish in general.