Karyotype Diversity in Two Populations of Rhamdia quelen (Pisces, Heptapteridae)
2004 年 69 巻 1 号 p. 25-34
詳細
2004 年 69 巻 1 号 p. 25-34
Cytogenetic studies in 2 populations of Rhamdia quelen collected from the Taquarussu river and Maringá stream were carried out. Both populations showed diploid number 2n=58 chromosomes but differed in relation to the caryotype formulae (26M+20SM+6ST+6A, 26M+22SM+6ST+4A respectualy). Beside the Taquarussu population showed 1 to 4 metacentric B chromosomes. Different-sized of B chromosomes were reported: middle-sized were more frequent; large-sized ones were found in only one specimen. Maringá population showed karyotypic variation in 22% of the individual (26M+24SM+8ST), 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 A3 coloration revealed NOR to be CMA3 positive in the 2 populations and consequently rich in GC. B chromosomes are CMA3 negative.
