title: Single origin of sex chromosomes and multiple origins of B chromosomes in fish genus Characidium.
abstract: Chromosome painting with DNA probes obtained from supernumerary (B) and sex chromosomes in three species of fish genus Characidium (C. gomesi, C. pterostictum and C. oiticicai) showed a close resemblance in repetitive DNA content between B and sex chromosomes in C. gomesi and C. pterostictum. This suggests an intraspecific origin for B chromosomes in these two species, probably deriving from sex chromosomes. In C. oiticicai, however, a DNA probe obtained from its B chromosome hybridized with the B but not with the A chromosomes, suggesting that the B chromosome in this species could have arisen interspecifically, although this hypothesis needs further investigation. A molecular phylogenetic analysis performed on nine Characidium species, with two mtDNA genes, showed that the presence of heteromorphic sex chromosomes in these species is a derived condition, and that their origin could have been unique, a conclusion also supported by interspecific chromosome painting with a CgW probe derived from the W chromosome in C. gomesi. Summing up, our results indicate that whereas heteromorphic sex chromosomes in the genus Characidium appear to have had a common and unique origin, B chromosomes may have had independent origins in different species. Our results also show that molecular phylogenetic analysis is an excellent complement for cytogenetic studies by unveiling the direction of evolutionary chromosome changes.
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Pansonato-Alves
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: Érica  Alves
authors.initials: É
authors.lastname: Serrano
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Utsunomia
authors.affiliation: Universidad de Granada, Departamento de Genetica, Granada, Spain.
authors.forename: Juan Pedro M
authors.initials: JP
authors.lastname: Camacho
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: Guilherme José
authors.initials: GJ
authors.lastname: da Costa Silva
authors.affiliation: Universidade Estadual de Ponta Grossa, Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, Paraná, Brazil.
authors.forename: Marcelo Ricardo
authors.initials: MR
authors.lastname: Vicari
authors.affiliation: Universidade Estadual de Ponta Grossa, Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, Paraná, Brazil.
authors.forename: Roberto Ferreira
authors.initials: RF
authors.lastname: Artoni
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: Cláudio
authors.initials: C
authors.lastname: Oliveira
authors.affiliation: Universidade Estadual Paulista (UNESP), Instituto de Biociências/IB, Departamento de Morfologia, Botucatu, São Paulo, Brazil.
authors.forename: Fausto
authors.initials: F
authors.lastname: Foresti
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D060125:Characiformes / Q000235:genetics*; D002871:Chromosome Banding; D016000:Cluster Analysis; D020732:Cytogenetic Analysis; D004272:DNA, Mitochondrial; D019143:Evolution, Molecular; D005260:Female; D005843:Geography; D017404:In Situ Hybridization, Fluorescence; D059785:Karyotype; D008297:Male; D010802:Phylogeny; D012730:Sex Chromosomes
chemical_list: D004272:DNA, Mitochondrial