title: Structurally Complex Organization of Repetitive DNAs in the Genome of Cobia (Rachycentron canadum).
abstract: Repetitive DNAs comprise the largest fraction of the eukaryotic genome. They include microsatellites or simple sequence repeats (SSRs), which play an important role in the chromosome differentiation among fishes. Rachycentron canadum is the only representative of the family Rachycentridae. This species has been focused on several multidisciplinary studies in view of its important potential for marine fish farming. In the present study, distinct classes of repetitive DNAs, with emphasis on SSRs, were mapped in the chromosomes of this species to improve the knowledge of its genome organization. Microsatellites exhibited a diversified distribution, both dispersed in euchromatin and clustered in the heterochromatin. The multilocus location of SSRs strengthened the heterochromatin heterogeneity in this species, as suggested by some previous studies. The colocalization of SSRs with retrotransposons and transposons pointed to a close evolutionary relationship between these repetitive sequences. A number of heterochromatic regions highlighted a greater complex organization than previously supposed, harboring a diversity of repetitive elements. In this sense, there was also evidence of colocalization of active genetic regions and different classes of repetitive DNAs in a common heterochromatic region, which offers a potential opportunity for further researches regarding the interaction of these distinct fractions in fish genomes.
authors.affiliation: 1 Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte , Natal, Brazil .
authors.forename: Gideão W W F
authors.initials: GW
authors.lastname: Costa
authors.forename: Marcelo de B
authors.initials: Mde B
authors.lastname: Cioffi
authors.forename: Luiz A C
authors.initials: LA
authors.lastname: Bertollo
authors.forename: Wagner F
authors.initials: WF
authors.lastname: Molina
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004247:DNA / Q000302:isolation & purification; D016678:Genome; D006570:Heterochromatin; D017404:In Situ Hybridization, Fluorescence; D010473:Perciformes / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
chemical_list: D006570:Heterochromatin; D004247:DNA