title: Cytogenetic analysis of the 18S, 5S rDNA and B chromosome of Iheringichthys labrosus (Lütken, 1874) (Siluriformes, Pimelodidae).
abstract: Cytogenetic analyses of the location of 18S and 5S ribosomal DNAs, and the base composition of B chromosomes of Iheringichthys labrosus from Tibagi River, Paraná, Brazil, are provided. AgNORs were observed in the terminal position on the long arm of a subtelocentric chromosome pair. CMA3-positive staining was observed in some chromosomes, which besides being associated with NORs, were all DAPI-negative. Chromosome B showed a strong fluorescence with CMA3. The concomitant use of 18S and 5S rDNA probes using the FISH technique revealed 18S ribosomal cistrons in a pair of subtelocentric chromosomes, on the long arm in the terminal position, coinciding with the AgNOR. The 5S sites were found in another subtelocentric pair, on the long arm in the interstitial region, near the centromere. The findings of the present study suggest that, although there are some more conserved cytogenetic characteristics, populations of I. labrosus may show their own characteristics.
authors: Departamento de Biologia Celular e Genética, Centro de Ciências Biológicas, Universidade Estadual de Maringá, Maringá, PR, Brazil.
authors: R A
authors: RA
authors: Carvalho
authors: A
authors: A
authors: Laudicina
authors: L
authors: L
authors: Giuliano-Caetano
authors: I C
authors: IC
authors: Martins-Santos
authors: A L
authors: AL
authors: Dias
mesh_terms: D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000235:genetics*; D002871:Chromosome Banding / Q000379:methods*; D004275:DNA, Ribosomal / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012341:RNA, Ribosomal, 5S / Q000235:genetics*; D045483:Rivers
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S; D012341:RNA, Ribosomal, 5S