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Karyotype Diversity in Two Populations of Rhamdia quelen (Pisces, Heptapteridae)

2004; International Society of Cytology; Volume: 69; Issue: 1 Linguagem: Inglês

10.1508/cytologia.69.25

1348-7019

Marcia Keller Stivari, Isabel Cristina Martins-Santos,

Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities

Cytogenetic studies in 2 populations of Rhamdia quelen collected from the Taquarussu river and Maringá stream were carried out.Both populations showed diploid number 2nϭ58 chromosomes but differed in relation to the caryotype formulae (26Mϩ20SMϩ6STϩ6A, 26Mϩ22SMϩ 6STϩ4A respectualy).Beside the Taquarussu population showed 1 to 4 metacentric B chromosomes.Different-sized of B chromosomes were reported: middle-sized were more frequent; largesized ones were found in only one specimen.Maringá population showed karyotypic variation in 22% of the individual (26Mϩ24SMϩ8ST), indicating the occurrence of structural rearrangements.Ag-NOR analysis revealed simple NOR system for both, although there were differences in the region's bearer pair type.C-banding results showed weak telomere or centromere markings in certain chromosomes and more evident bands in the NOR region and at the extremities of the 2 B chromosome types.Chromomycin A 3 coloration revealed NOR to be CMA 3 positive in the 2 populations and consequently rich in GC.B chromosomes are CMA 3 negative.