Chromosomal localization of 5S rDNA genes in Leporinus fish (Anostomidae, Characiformes)

The large 45S rDNA chromosome sites have often been analyzed in fish. In co ntrast, little is known about the 5S genes in this animal group. In the gen us Leporinus, the NOR chromosomal location has been shown to be very divers e. In the present work, chromosome mapping of 5S rDNA in three anostomids, Leporinus elongatus, L. obtusidens and L. friderici, is investigated using fluorescence in-situ hybridization (FISH) with PCR-obtained 5S probes and p rimed in-situ labeling (PRINS). Major 5S rDNA chromosomal sites were found to be subterminally located in a small metacentric pair, while minor ones w ere detected near the centromeric region of a medium-sized submetacentric p air in all studied species. The 5S rDNA genes were not associated with the NORs or sex chromosomes. A highly conserved chromosomal location of these g enes appears to characterize the karyotype evolution of this fish group.