title: Evolutionary dynamics of rDNA genes on chromosomes of the Eucinostomus fishes: cytotaxonomic and karyoevolutive implications.
abstract: Several chromosomal features of Gerreidae fish have been found to be conserved. In this group, it is unclear whether the high degree of chromosomal stasis is maintained when analyzing more dynamic regions of chromosomes, such as rDNA sites that generally show a higher level of variability. Thus, cytogenetic analyses were performed on 3 Atlantic species of the genus Eucinostomus using conventional banding (C-banding, Ag-NOR), AT- and GC-specific fluorochromes, and fluorescence in situ hybridization mapping of telomeric sequences and 5S and 18S rDNA sites. The results showed that although the karyotypical macrostructure of these species is similar (2n = 48 chromosomes, simple Ag-NORs seemingly located on homeologous chromosomes and centromeric heterochromatin pattern), there are differences in the positions of rDNA subunits 5S and 18S. Thus, the ribosomal sites have demonstrated to be effective cytotaxonomic markers in Eucinostomus, presenting a different evolutionary dynamics in relation to other chromosomal regions and allowing access to important evolutionary changes in this group.
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
authors.forename: L L
authors.initials: LL
authors.lastname: Calado
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
authors.forename: L A C
authors.initials: LA
authors.lastname: Bertollo
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, SP, Brasil.
authors.forename: M B
authors.initials: MB
authors.lastname: Cioffi
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
authors.forename: G W W F
authors.initials: GW
authors.lastname: Costa
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil.
authors.forename: U P
authors.initials: UP
authors.lastname: Jacobina
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brasil molinawf@yahoo.com.br.
authors.forename: W F
authors.initials: WF
authors.lastname: Molina
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D005399:Fishes / Q000145:classification* / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012341:RNA, Ribosomal, 5S / Q000235:genetics
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S; D012341:RNA, Ribosomal, 5S