B chromosomes: an update about their occurrence in freshwater Neotropical fishes (Teleostei) |
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Authors: | R A Carvalho † I C Martins-Santos A L Dias †‡ |
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Institution: | Departamento de Genética e Biologia Celular, CCB, Universidade Estadual de Maringá, Avenida Colombo, 5790 - CEP 87020-900, Maringá, Paraná, Brazil; and Departamento de Biologia Geral, CCB, Universidade Estadual de Londrina, CEP 86051-970, Caixa Postal 6001, Londrina, Paraná, Brazil |
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Abstract: | In freshwater Neotropical fishes, supernumerary chromosomes or B chromosomes have been found in 61 species so far, distributed in 16 families of seven different orders and in distinct hydrographic basins. The order Characiformes is the one that possesses the most species with these chromosomes, including 31 species from six different families. The order Siluriformes has 21 species from five families, with Rhamdia , of the family Heptapteridae, being the most common genus where these chromosomes are found. The order Perciformes has five species with B chromosomes in only one family, Cichlidae, and the orders Beloniformes, Cyprinodontiformes, Gymnotiformes and Synbranchiformes contain only one species each with extra chromosomes. They are found as microchromosomes in Schizodon , Astyanax , Moenkhausia , Cyphocharax , Steindachnerina , Prochilodus , Rhamdia , Iheringichthys and Loricaria , among others, up to supernumerary macrochromosomes as in Astyanax , varying in morphology as well as number, showing evidence of the wide diversity of B chromosomes in Neotropical fishes. |
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Keywords: | cytogenetic fish review supernumerary chromosomes |
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