Chromosomal characteristics of rDNA in a conserved karyotype of two Sternopygus macrurus (Gymnotiformes: Sternopygidae) populations from upper Paraná River basin

• Published in: Biológia Vol. 72; no. 6; pp. 680 - 685
• Main Authors: Fernandes, Carlos Alexandre, Baumgärtner, Lucas, Paiz, Leonardo Marcel, Margarido, Vladimir Pavan, de Brito Portela-Castro, Ana Luiza
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.06.2017; De Gruyter; Springer Nature B.V
• Subjects: Banding; Cell Biology; chromosome banding; Chromosome number; Chromosomes; Cytogenetics; fish cytogenetics; Fish populations; Fluorescence; Fluorescence in situ hybridization; Fluorescent indicators; Fluorophores; Karyotypes; Life Sciences; Microbiology; Neotropical fishes; NORs; Nucleoli; Plant Sciences; Populations; Probes; repetitive sequences; River basins; Rivers; Staining; Sternopygus macrurus; Synteny; Taxa; Zoology; Neotropical fishes; fish cytogenetics; NORs; repeitive sequences; chromosome banding
• ISSN: 0006-3088; 1336-9563
• DOI: 10.1515/biolog-2017-0071

Karyotype and chromosomal characteristics of both minor and major rDNA of Sternopygus macrurus , a weakly electric South American fish, from two populations of the upper Paraná River basin, were investigated using conventional (Giemsa staining, silver staining, C-banding and base-specific fluorochromes) and molecular (fluorescent in situ hybridization (FISH) with 5S and 18S rDNA probes) cytogenetic techniques. Diploid chromosome number was invariably 2 n = 46 and karyotype composed of 23 pairs of biarmed chromosomes (28m+18sm). The nucleolus organizer regions (NORs) were located in the secondary constriction of the p arm of pair No. 2; this site corresponded with CMA3 positive as well as with 18S rDNA signals, respectively. This 18S rDNA cluster was not syntenic to the 5S rDNA sites located at pairs Nos. 1, 5 and 15. The karyotypes and other chromosomal characteristics of individuals from the two populations in the upper Paraná River basin were identical. The karyotype differences among individuals identified as S. macrurus from Paraná River and the S˜ao Francisco and Amazon River basins, respectively, may indicate that these taxa might represent distinct species.