title: Chromosomal mapping of repetitive DNAs in Triportheus trifurcatus (Characidae, Characiformes): insights into the differentiation of the Z and W chromosomes.
abstract: Repetitive DNA sequences play an important role in the structural and functional organization of chromosomes, especially in sex chromosome differentiation. The genus Triportheus represents an interesting model for such studies because all of its species analyzed so far contain a ZZ/ZW sex chromosome system. A close relationship has been found between the differentiation of the W chromosome and heterochromatinization, with the involvement of different types of repetitive DNA in this process. This study investigated several aspects of this association in the W chromosome of Triportheus trifurcatus (2 n = 52 chromosomes), including the cytogenetic mapping of repetitive DNAs such as telomeric sequences (TTAGGG)n, microsatellites and retrotransposons. A remarkable heterochromatic segment on the W chromosome was observed with a preferential accumulation of (CAC)10, (CAG)10, (CGG)10, (GAA)10 and (TA)15. The retrotransposons Rex1 and Rex3 showed a general distribution pattern in the chromosomes, and Rex6 showed a different distribution on the W chromosome. The telomeric repeat (TTAGGG)n was highly evident in both telomeres of all chromosomes without the occurrence of ITS. Thus, the differentiation of the W chromosome of T. trifurcatus is clearly associated with the formation of heterochromatin and different types of repetitive DNA, suggesting that these elements had a prominent role in this evolutionary process.
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
authors.forename: Cassia Fernanda
authors.initials: CF
authors.lastname: Yano
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: Poltronieri
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
authors.forename: Luiz Antonio Carlos
authors.initials: LA
authors.lastname: Bertollo
authors.affiliation: Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa, Ponta Grossa, PR, Brazil.
authors.forename: Roberto Ferreira
authors.initials: RF
authors.lastname: Artoni
authors.affiliation: Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Jena, Thüringen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Liehr
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: de Bello Cioffi
mesh_terms: D000818:Animals; D060126:Characidae / Q000235:genetics*; D002874:Chromosome Mapping; D004247:DNA / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D012730:Sex Chromosomes / Q000235:genetics*; D016615:Telomere / Q000235:genetics
chemical_list: D004247:DNA