Dinâmica evolutiva de elementos de transposição nas espécies irmãs Rhodnius robustus e R. prolixus
Carregando...
Data
2019-02-22
Autores
Castro, Marcelo Roman Jurado
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os elementos de transposição (TEs) são sequências repetitivas amplamente distribuídas nos genomas que representam importantes fontes geradoras de variabilidade genética. As características genômicas derivadas de sua capacidade de transposição e de aumento do número de cópias são específicas para cada linhagem. Um fenômeno derivado dessa habilidade é o incremento repentino do número de cópias, denominado explosões de transposição, descrito em várias espécies para diversas famílias de TEs, dentre elas, a família Mariner (Transposon de DNA, Classe II) em Rhodnius prolixus. Foi sugerido que explosões de transposição da família Mariner contribuíram para o processo de especiação de R. prolixus. Esta peculiaridade motivou o estudo da composição do mobiloma em R. robustus, espécie irmã de R. prolixus, juntamente a reanotação dos TEs de R. prolixus, para comparação do mobiloma das duas espécies. Para isso, foram realizados sequenciamentos NGS (Next Generation Sequencing) dos genomas de dois tipos genéticos de R. robustus (II e III), montagem e anotação dos TEs utilizando a ferramenta dnaPipeTE. Da mesma forma, foram anotados os TEs de R. prolixus a partir das reads brutas do seu genoma montado. Os resultados mostraram alta semelhança na frequência de TEs nos três genomas (R. prolixus: 19%, R. robustus II: 23,5%, R. robustus III: 21,5%), constituídos principalmente de TEs de Classe II (~13,5%) da superfamília Tc1-Mariner (~5,6%) e de da Ordem LINE, da Classe I (~5,1%). A comparação dos três mobilomas revelou três características importantes para se entender a dinâmica evolutiva destes TEs: (i) compartilhamento de famílias que ocorrem tanto em alta como em baixa proporção entre genomas; (ii) compartilhamento de famílias que ocorrem em proporções dissimilares entre genomas, alta em um e baixa no outro, e (iii) não compartilhamento de determinadas famílias entre genomas. Identificou-se ainda sinais de explosões de transposição recentes da família Mariner em R. robustus II e III, indicando que esse fenômeno não foi exclusivo de R. prolixus, estando, portanto, não associado diretamente à especiação das duas espécies irmãs.
Transposable elements (TEs) are widely distributed repetitive sequences in the genomes that represent important sources of genetic variability. The genomic characteristics derived from their capacity of transposition and increasing in copy number are specific to each lineage. A phenomenon derived from this ability is the sudden increase of one or several families of TEs, called bursts of transposition, described in several species for several families of TEs, among them the Mariner family (DNA Transposons, Class II) in Rhodnius prolixus. It has been suggested that transposition bursts of the Mariner family contributed to the speciation process of R. prolixus. This peculiarity motivated the study of the mobilome composition of R. robustus, together with its reannotation in R. prolixus, for comparison of the mobilome of the two species. In order to do this, we performed NGS (Next Generation Sequencing) sequencing of the genomes of two genetic types of R. robustus (II and III) and the assembly and annotation of the TEs using the pipeline dnaPipeTE. Likewise, the TEs of R. prolixus were annotated from the raw reads of its assembled genome. The results showed high similarity in the frequency of TEs in the three genomes (R. prolixus: 19%, R. robustus II: 23.5%, R. robustus III: 21.5%), consisting mainly of TEs from Class II (~13.5%) of the superfamily Tc1-Mariner (~5.6%) and of the LINE Order, Class I (~5.1%). The comparison of the three mobilomes revealed three important characteristics to understand the evolutionary dynamics of these TEs: (i) sharing of families that occur both in high and low proportion between genomes; (ii) sharing of families occurring in dissimilar proportions between genomes, high in one and low in the other, and (iii) non-sharing of a family between genomes. There are also signs of recent burst of transposition of the Mariner family in R. robustus II and III, indicating that this phenomenon was not exclusive to R. prolixus, therefore not directly associated with the speciation of the two sister species.
Transposable elements (TEs) are widely distributed repetitive sequences in the genomes that represent important sources of genetic variability. The genomic characteristics derived from their capacity of transposition and increasing in copy number are specific to each lineage. A phenomenon derived from this ability is the sudden increase of one or several families of TEs, called bursts of transposition, described in several species for several families of TEs, among them the Mariner family (DNA Transposons, Class II) in Rhodnius prolixus. It has been suggested that transposition bursts of the Mariner family contributed to the speciation process of R. prolixus. This peculiarity motivated the study of the mobilome composition of R. robustus, together with its reannotation in R. prolixus, for comparison of the mobilome of the two species. In order to do this, we performed NGS (Next Generation Sequencing) sequencing of the genomes of two genetic types of R. robustus (II and III) and the assembly and annotation of the TEs using the pipeline dnaPipeTE. Likewise, the TEs of R. prolixus were annotated from the raw reads of its assembled genome. The results showed high similarity in the frequency of TEs in the three genomes (R. prolixus: 19%, R. robustus II: 23.5%, R. robustus III: 21.5%), consisting mainly of TEs from Class II (~13.5%) of the superfamily Tc1-Mariner (~5.6%) and of the LINE Order, Class I (~5.1%). The comparison of the three mobilomes revealed three important characteristics to understand the evolutionary dynamics of these TEs: (i) sharing of families that occur both in high and low proportion between genomes; (ii) sharing of families occurring in dissimilar proportions between genomes, high in one and low in the other, and (iii) non-sharing of a family between genomes. There are also signs of recent burst of transposition of the Mariner family in R. robustus II and III, indicating that this phenomenon was not exclusive to R. prolixus, therefore not directly associated with the speciation of the two sister species.
Descrição
Palavras-chave
Elementos de transposição, Explosões de transposição, Elementos Mariner, Especiação, Rhodnius robustus, Rhodnius prolixus, Transposable elements, Burst of transposition, Mariner elements, Speciation