Identification and description of distinct B chromosomes in Cyphocharax modestus (Characiformes, Curimatidae)
Genet. mol. biol
;
31(1,suppl): 265-269, 2008. ilus, tab
Article
in English
| LILACS
| ID: lil-484598
ABSTRACT
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.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Chromosome Banding
/
Fishes
Type of study:
Diagnostic study
/
Risk factors
Limits:
Animals
Language:
English
Journal:
Genet. mol. biol
Journal subject:
Genetics
Year:
2008
Type:
Article
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Estadual Paulista/BR
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