title: Repetitive sequences: the hidden diversity of heterochromatin in prochilodontid fish.
abstract: The structure and organization of repetitive elements in fish genomes are still relatively poorly understood, although most of these elements are believed to be located in heterochromatic regions. Repetitive elements are considered essential in evolutionary processes as hotspots for mutations and chromosomal rearrangements, among other functions - thus providing new genomic alternatives and regulatory sites for gene expression. The present study sought to characterize repetitive DNA sequences in the genomes of Semaprochilodus insignis (Jardine & Schomburgk, 1841) and Semaprochilodus taeniurus (Valenciennes, 1817) and identify regions of conserved syntenic blocks in this genome fraction of three species of Prochilodontidae (Semaprochilodus insignis, Semaprochilodus taeniurus, and Prochilodus lineatus (Valenciennes, 1836) by cross-FISH using Cot-1 DNA (renaturation kinetics) probes. We found that the repetitive fractions of the genomes of Semaprochilodus insignis and Semaprochilodus taeniurus have significant amounts of conserved syntenic blocks in hybridization sites, but with low degrees of similarity between them and the genome of Prochilodus lineatus, especially in relation to B chromosomes. The cloning and sequencing of the repetitive genomic elements of Semaprochilodus insignis and Semaprochilodus taeniurus using Cot-1 DNA identified 48 fragments that displayed high similarity with repetitive sequences deposited in public DNA databases and classified as microsatellites, transposons, and retrotransposons. The repetitive fractions of the Semaprochilodus insignis and Semaprochilodus taeniurus genomes exhibited high degrees of conserved syntenic blocks in terms of both the structures and locations of hybridization sites, but a low degree of similarity with the syntenic blocks of the Prochilodus lineatus genome. Future comparative analyses of other prochilodontidae species will be needed to advance our understanding of the organization and evolution of the genomes in this group of fish.
authors.affiliation: Federal University of Integration American-Latin (Universidade Federal da Integração Latino-Americana), Laboratory of Genetics, Av. Tarquínio Joslin dos Santos, 1000, Jardim Universitário, Foz do Iguaçu, PR, Brazil 85857-190.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Terencio
authors.affiliation: Federal University of Amazonas (Universidade Federal do Amazonas), Institute of Biological Sciences, Department of Genetics, Laboratory of Animal Cytogenomics, Manaus, AM, Brazil.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Schneider
authors.affiliation: Federal University of Amazonas (Universidade Federal do Amazonas), Institute of Biological Sciences, Department of Genetics, Laboratory of Animal Cytogenomics, Manaus, AM, Brazil.
authors.forename: Maria C
authors.initials: MC
authors.lastname: Gross
authors.affiliation: Federal University of Amazonas, Institute of Biological Sciences, Laboratory of DNA Technologies, Manaus, AM, Brazil.
authors.forename: Edson Junior
authors.initials: EJ
authors.lastname: do Carmo
authors.affiliation: State University of Ponta Grossa, Department of Structural and Molecular Biology and Genetics, Laboratory of Cytogenetics and Evolution, Ponta Grossa, PR, Brazil.
authors.forename: Viviane
authors.initials: V
authors.lastname: Nogaroto
authors.affiliation: State University of Ponta Grossa, Department of Structural and Molecular Biology and Genetics, Laboratory of Cytogenetics and Evolution, Ponta Grossa, PR, Brazil.
authors.forename: Mara Cristina
authors.initials: MC
authors.lastname: de Almeida
authors.affiliation: State University of Ponta Grossa, Department of Structural and Molecular Biology and Genetics, Laboratory of Cytogenetics and Evolution, Ponta Grossa, PR, Brazil.
authors.forename: Roberto Ferreira
authors.initials: RF
authors.lastname: Artoni
authors.affiliation: State University of Ponta Grossa, Department of Structural and Molecular Biology and Genetics, Laboratory of Cytogenetics and Evolution, Ponta Grossa, PR, Brazil.
authors.forename: Marcelo R
authors.initials: MR
authors.lastname: Vicari
authors.affiliation: National Institute of Amazonian Research, Laboratory of Animal Genetics, Av. André Araújo, 2936, Petrópolis, Manaus, AM, Brazil 69011-970.
authors.forename: Eliana
authors.initials: E
authors.lastname: Feldberg
keywords: Chromosomal painting; Fish; microsatellites; repetitive sequences; sex chromosome; transposable elements