Identification and description of distinct B chromosomes in Cyphocharax modestus (Characiformes, Curimatidae)
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Data
2008-01-01
Autores
Santos, Lessandra Viviane de Rosa [UNESP]
Foresti, Fausto [UNESP]
Martins, Cesar [UNESP]
Oliveira, Claudio [UNESP]
Wasko, Adriane Pinto [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Genética
Resumo
Cytogenetic analyses were performed in Cyphocharax modestus, collected at Paranapanema River and Tietê River (São Paulo State, Brazil). A karyotype with 2n = 54 chromosomes was observed in the animals from both Brazilian freshwater river systems. One to four B chromosomes were also detected in individuals from the Paranapanema River, which represents the probable first report of more than a single supernumerary element in a species of the Curimatidae group. C-banding revealed centromeric and telomeric heterochromatin blocks in several chromosomes of the normal karyotype complement of C. modestus. Moreover, while some B chromosomes were characterized by the complete absence of C-bands, others were totally heterochromatic. Although there was a prevalence of B chromosomes in males of C. modestus, at least one supernumerary element was found in males and/or females of several other populations of the species, which suggests that the presence of these chromosomes seems to represent a general trait of C. modestus. A possible origin of the described B chromosomes may be related to the occurrence of a chromosome non-disjunction followed by the loss of euchromatic segments, an event that should have occurred in chromosomes that present conspicuous centromeric heterochromatic blocks and even in chromosomes that lack C-bands in this region, resulting in small supernumerary elements.
Descrição
Palavras-chave
B chromosomes, C-banding, Curimatidae, Cyphocharax modestus, supernumerary chromosomes
Como citar
Genetics and Molecular Biology. Sociedade Brasileira de Genética, v. 31, n. 1, p. 265-269, 2008.