Silencing of Transposable Elements Mediated by 5-mC and Compensation of the Heterochromatin Content by Presence of B Chromosomes in <i>Astyanax scabripinnis</i>
Patrícia Barbosa,
Zelinda Schemczssen-Graeff,
André Marques,
Maelin da Silva,
Giovani Marino Favero,
Bernardo Passos Sobreiro,
Mara Cristina de Almeida,
Orlando Moreira-Filho,
Duílio Mazzoni Zerbinato de Andrade Silva,
Fábio Porto-Foresti,
Fausto Foresti,
Roberto Ferreira Artoni
Affiliations
Patrícia Barbosa
Post Graduate Program in Evolutionary Genetics and Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washington Luís Km 235, São Carlos 13565-905, SP, Brazil
Zelinda Schemczssen-Graeff
Post Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil
André Marques
Department of Botany, Federal University of Pernambuco, Recife 50670-901, PE, Brazil
Maelin da Silva
Post Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil
Giovani Marino Favero
Department of General Biology, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil
Bernardo Passos Sobreiro
Department of Medicine, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil
Mara Cristina de Almeida
Post Graduate Program in Evolutionary Biology, Department of Structural, Molecular and Genetic Biology, State University of Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa 84030-900, PR, Brazil
Orlando Moreira-Filho
Post Graduate Program in Evolutionary Genetics and Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washington Luís Km 235, São Carlos 13565-905, SP, Brazil
Duílio Mazzoni Zerbinato de Andrade Silva
Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University (UNESP), Botucatu 18618-689, SP, Brazil
Fábio Porto-Foresti
Faculty of Sciences, Sao Paulo State University (UNESP), Bauru 01049-010, SP, Brazil
Fausto Foresti
Department of Structural and Functional Biology, Institute of Biosciences at Botucatu, Sao Paulo State University (UNESP), Botucatu 18618-689, SP, Brazil
Roberto Ferreira Artoni
Post Graduate Program in Evolutionary Genetics and Molecular Biology, Department of Genetics and Evolution, Federal University of São Carlos, Rodovia Washington Luís Km 235, São Carlos 13565-905, SP, Brazil
The way in which transcriptional activity overcomes the physical DNA structure and gene regulation mechanisms involves complex processes that are not yet fully understood. Modifications in the cytosine-guanine sequence of DNA by 5-mC are preferentially located in heterochromatic regions and are related to gene silencing. Herein, we investigate evidence of epigenetic regulation related to the B chromosome model and transposable elements in A. scabripinnis. Indirect immunofluorescence using anti-5-mC to mark methylated regions was employed along with quantitative ELISA to determine the total genomic DNA methylation level. 5-mC signals were dispersed in the chromosomes of both females and males, with preferential accumulation in the B chromosome. In addition to the heterochromatic methylated regions, our results suggest that methylation is associated with transposable elements (LINE and Tc1-Mariner). Heterochromatin content was measured based on the C-band length in relation to the size of chromosome 1. The B chromosome in A. scabripinnis comprises heterochromatin located in the pericentromeric region of both arms of this isochromosome. In this context, individuals with B chromosomes should have an increased heterochromatin content when compared to individuals that do not. Although, both heterochromatin content and genome methylation showed no significant differences between sexes or in relation to the occurrence of B chromosomes. Our evidence suggests that the B chromosome can have a compensation effect on the heterochromatin content and that methylation possibly operates to silence TEs in A. scabripinnis. This represents a sui generis compensation and gene activity buffering mechanism.
