%0 Journal Article
%T Cytogenetic comparison between two allopatric populations of Astyanax altiparanae Garutti & Britski, 2000 (Teleostei, Characidae), with emphasis on the localization of 18S and 5S rDNA
%A R. B. Pacheco
%A Renata Rosa
%A L. Giuliano-Caetano
%A H. F. J¨˛lio Jr.
%J Comparative Cytogenetics
%D 2011
%I Pensoft Publishers
%R 10.3897/compcytogen.v5i3.1235
%X Two populations of Astyanax altiparanae (Garutti et Britski, 2000) of the ¨˘gua dos Patos stream/SP and lake Igap¨®/PR were analyzed. All individuals showed 2n = 50, however, different karyotypic formulae were observed. The population of the ¨˘gua dos Patos stream showed 8m +24sm+6st+12a (NF=88) and the population of lake Igap¨®, 8m+28sm+4st+10a (NF=90). Nucleolus organizing regions (AgNORs) were observed in the terminal position on the short and long arm of different chromosomes of both populations, showing a variation from 3 to 4 chromosomes. Fluorescent in situ hybridization (FISH) using 18S rDNA probes revealed only one pair of chromosomes with fluorescent signals in the terminal site on the short arm in the Igap¨® lake population, while the population of ¨˘gua dos Patos stream showed 4 fluorescence terminal signals, characterizing a system of simple and multiple NORs, respectively. 5S rDNA fluorescent signals were detected in the interstitial position of a pair of chromosomes in the two studied populations. Some AgNOR sites revealed to be GC-rich when stained with Chromomycin A3 (CMA3), however, AT positive regions were not observed. The data obtained show that, despite the conservation of the diploid number and location of 5S DNAr, differences in both the distribution of 18S rDNA and karyotypic formula among the populations were found, thus corroborating the existing data on chromosome variability in Astyanax altiparanae that can be significant for cytotaxonomy in this group.
%K Incertae sedis
%K FISH
%K karyotypic formulae
%K NORs
%U http://www.pensoft.net/journals/compcytogen/article/1235/