title: Karyotype diversity of four species of the incertae  sedis group (Characidae) from different hydrographic basins: analysis of  AgNORs, CMA3 and 18S rDNA.
abstract: A large number of genera in the tropical fish family  Characidae are incertae sedis. Cytogenetic analysis was made of four of  these species: Astyanax eigenmanniorum, Deuterodon stigmaturus, Hyphessobrycon  luetkenii, and H. anisitsi, collected from various hydrographic  basins: hydrographic system from Laguna dos Patos/RS, Tramandaí basin/RS and  Tibagi River basin/PR. The first two species were collected in their type  locality in the State of Rio Grande do Sul. The 2n = 48 karyotype was observed  only in A. eigenmanniorum, while the other species had 2n = 50  chromosomes, with different karyotypic formulas. There was weak heterochromatin  staining in the pericentromeric region of A. eigenmanniorum, D.  stigmaturus and H. luetkenni chromosomes. In H. anisitsi,  heterochromatin appeared to be more abundant and distributed in the  pericentromeric and terminal regions of the chromosomes; three pairs showed  more evident heterochromatic blocks. There were multiple Ag-NORs in all  populations, visualized by FISH with an 18S rDNA probe. While D. stigmaturus and H. luetkenii had  conserved AgNOR, CMA3 and 18S rDNA sites, the other two species showed  intra- and interindividual variation at these sites. The karyotype variability  was high, as is common in this group of fish. Different species arising from  isolated hydrographic basins maintain an elevated level of karyotype  differentiation, mainly with respect to chromosome structure, heterochromatin  distribution and rDNA localization. This is the first report with cytogenetic  data for D. stigmaturus and H. luetkenii.
authors.affiliation: Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, PR, Brasil.
authors.forename: M M
authors.initials: MM
authors.lastname: Mendes
authors.forename: R
authors.initials: R
authors.lastname: da Rosa
authors.forename: L
authors.initials: L
authors.lastname: Giuliano-Caetano
authors.forename: A L
authors.initials: AL
authors.lastname: Dias
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear / Q000235:genetics*; D001938:Brazil; D060126:Characidae / Q000145:classification* / Q000235:genetics*; D014128:Chromomycin A3 / Q000378:metabolism*; D002871:Chromosome Banding; D002875:Chromosomes / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D005843:Geography; D017404:In Situ Hybridization, Fluorescence; D007211:Indoles / Q000378:metabolism; D007621:Karyotyping; D008297:Male; D008677:Metaphase / Q000235:genetics; D045483:Rivers; D013045:Species Specificity
chemical_list: D034961:Antigens, Nuclear; D004275:DNA, Ribosomal; D007211:Indoles; C051963:nucleolar organizer region associated proteins; C007293:DAPI; D014128:Chromomycin A3