Occurrence of natural triploidy in Rhamdia quelen(Siluriformes, Heptapteridae)

J.R. Tsuda, V.P.O. de Moraes, L. Giuliano-Caetano and A.L. Dias
Published September 28, 2010
Genet. Mol. Res. 9 (3): 1929-1935 (2010)
DOI 10.4238/vol9-3gmr949

About the authors
J.R. Tsuda, V.P.O. de Moraes, L. Giuliano-Caetano and A.L. Dias

Corresponding author
A.L. Dias
E-mail: anadias@uel.br


 Five specimens of Rhamdia quelen collected from the Lindóia Stream, PR, Brazil, were cytogenetically analyzed. The diploid chromosome number found was 58, including 30 metacentric, 16 submetacentric, 10 subtelocentric, and 2 acrocentric chromosomes. Supernumerary or B chromosomes, frequently observed in this fish group, were not detected. One of the individuals was triploid, with 3n = 87. A silver-stained nucleolar organizer region was found on a pair of submetacentric chromosomes of the diploid specimens, and on three chromosomes of the triploid individual, confirming triploidy. Treatment with fluorochrome chromomycin A3 revealed fluorescent bands coincident with those of the silver-stained nucleolar organizer region, in both diploid and triploid individuals, showing that this is a GC-rich region. Heterochromatin distribution was visualized by the C-banding technique, mainly in the terminal chromosome regions of the individuals and was also observed in the pericentromeric regions of some chromosomes and at both telomeres.

Key words: Fish cytogenetics; Polyploidy; Triploid fish

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