%0 Journal Article
%T Cytogenetic analysis of B chromosomes in one population of the fish Moenkhausia sanctaefilomenae (Steindachner, 1907) (Teleostei, Characiformes)
%A Diogo Hashimoto
%A Tatiana Voltolin
%A Ana Paes
%A Fausto Foresti
%J Comparative Cytogenetics
%D 2012
%I Pensoft Publishers
%R 10.3897/compcytogen.v6i2.1769
%X The aim of this study was to characterize cytogenetically one population of the fish Moenkhausia sanctaefilomenae (Steindachner, 1907), with emphasis on the analysis of B chromosomes. The nucleolar activity in the B microchromosomes was characterized, and an analysis of mitotic instability of these microchromosomes was accomplished. The results showed a diploid chromosome number of 50 chromosomes. In all individuals, we observed the presence of B microchromosomes with intra- and inter-individual variability. The analysis of the nucleolus organizing regions (NORs) by silver nitrate staining demonstrated multiple NORs. We observed active sites of ribosomal DNA in the B microchromosomes, with a frequency of 20% in the analyzed cells, which shows gene activity in these chromosomal elements. The analysis of constitutive heterochromatin patterns showed that the B microchromosomes are heterochromatic or euchromatic, which demonstrates differentiation of DNA composition between these genomic elements. The calculation of the mitotic instability index implied that B chromosomes in this species might be in a final stage of instability.
%K fish cytogenetic
%K NOR expression
%K supernumerary chromosomes
%K mitotic instability
%U http://www.pensoft.net/journals/compcytogen/article/1769/