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Analysis of the nucleolus organizer regions in 5 species of the genus Pimelodus (Siluriformes, Pimelodidae), using AgNO 3 , CMA 3 and FISH with the 18S rDNA probe

2004; University of Florence; Volume: 57; Issue: 2 Linguagem: Inglês

10.1080/00087114.2004.10589384

2165-5391

Lenice de Souza, Ana Claúdia Swarça, Ana Lúcia Dias,

Genomics and Phylogenetic Studies

Abstract A cytogenetic study was conducted on five species of the genus Pimelodus collected from various regions in Brazil: Pimelodus heraldoi, Pimelodus sp, Pimelodus argenteus, P. maculatus and P. mysteriosus. All the species had 2n=56 chromosomes. AgNOR was found in one pair of subtelocentric (ST) chromosomes with staining at the terminal position in all the five species. However, Pimelodus sp, P. heraldoi and P. maculatus showed NOR staining on long arm and P. argenteus and P. mysteriosus showed NOR staining on the short arm. AgNOR size heteromorphism was observed in Pimelodus sp, P. maculatus and P. argenteus. The CMA3 fluorochrome staining pattern in all the species corresponded with AgNOR sites, also showing heteromorphism, including P. mysteriosus. FISH revealed the presence of one pair of chromosomes with ribosomal cistrons and confirmed the presence of the structural hetero-morphism of these sites, except in P. heraldoi.