B chromosomes in a population of Astyanax eigenmanniorum (Characiformes, Characidae) from the Araguari River Basin (Uberlândia, MG, Brazil)

A cytogenetic study was conducted on an Astyanax eigenmanniorum population from the Caetano Stream (18 degree 44' 56" S/ 048 degree 18' 39" W) - in Uberlandia, MG, Brazil - showing a modal diploid number of 48 chromosomes in the standard male and female karyotypes. However, in se...

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Bibliographic Details
Published in:Genetics and molecular biology 2008, Vol.31 (1 suppl), p.246-249
Main Authors: Torres-Mariano, Alessandra Ribeiro, Morelli, Sandra
Format: Article
Language:English
Subjects:
Astyanax eigenmanniorum
BIOCHEMISTRY & MOLECULAR BIOLOGY
Characidae
Characiformes
GENETICS & HEREDITY
heterochromatin
nucleolus organizing regions (NORs)
supernumerary chromosome
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Summary:A cytogenetic study was conducted on an Astyanax eigenmanniorum population from the Caetano Stream (18 degree 44' 56" S/ 048 degree 18' 39" W) - in Uberlandia, MG, Brazil - showing a modal diploid number of 48 chromosomes in the standard male and female karyotypes. However, in several specimens it was also possible to observe metaphases with one or two B chromosomes, increasing the diploid number to 49 or 50 chromosomes, respectively. The supernumerary chromosomes were totally heterochromatic and highlighted after C-banding. The silver-stained nucleolus organizing regions (Ag-NORs) were located in at least five chromosomes of the standard karyotype, thus characterizing a multiple NOR system in the species. This is the first occurrence of an A. eigenmanniorum population with 2n = 48 chromosomes, bearing supernumerary chromosomes.
ISSN:1415-4757
1678-4685
1415-4757
1678-4685
DOI:10.1590/S1415-47572008000200015