Chromosomal location of 5S and 18S rRNA genes in three sympatric cytotypes ofAstyanax scabripinnis(Characiformes, Characidae) from the Ivaí river basin, state of Paraná, Brazil

Abstract

Analyses of the distribution of rDNA genes (both 5S and 18S) using classical techniques, such as silver and CMA3 staining and FISH were carried out in specimens of Astyanax scabripinnis from Tatupeba stream (Ivaí river basin). The three cytotypes identified for this population presented multiple NOR system, with intra-populational numerical and positional variations, detected for Ag-NOR, CMA3 and 18S-FISH. In contrast, data obtained from rDNA-5S revealed a highly conserved chromosomal distribution pattern in each cytotype. Aspects on divergences among distribution pattern of sites 5S and 18S rDNA are discussed.