title: Genomic organization of repetitive DNAs and its implications for male karyotype and the neo-Y chromosome differentiation in Erythrinus erythrinus (Characiformes, Erythrinidae).
abstract: Studies have demonstrated the effective participation of repetitive DNA sequences in the origin and differentiation of the sex chromosomes in some biological groups. In this study several microsatellites and retrotranposable sequences were cytogenetically mapped in the Erythrinus erythrinus (Bloch & Schneider, 1801) male genome (karyomorph C), focusing on the distribution of these sequences in the sex chromosomes and in the evolutionary processes related to their differentiation. Males of E. erythrinus - karyomorph C - present 2n = 51 chromosomes (7m + 2sm + 6st + 36a), including the X1X2Y sex chromosomes. The C-positive heterochromatin has a predominant localization on the centromeric region of most chromosome pairs, but also in some telomeric regions. The 5S rDNA sites are located in the centromeric region of 27 chromosomes, including 26 acrocentric ones and the metacentric Y chromosome. The retrotransposons Rex 1 and Rex 6 show a dispersed pattern in the karyotype, contrasting with the Rex 3 distribution which is clearly co-localized with all the 27 5S rDNA sites. The microsatellite sequences show a differential distribution, some of them restricted to telomeric and/or interstitial regions and others with a scattered distribution on the chromosomes. However, no preferential accumulation of these elements were observed in the neo-Y chromosome, in contrast to what usually occurs in simple sex chromosome systems.
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís (SP 310) Km 235, São Carlos, SP, Brazil.
authors.forename: Cassia Fernanda
authors.initials: CF
authors.lastname: Yano
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís (SP 310) Km 235, São Carlos, SP, Brazil ; Professor Sênior at Universidade Federal de São Carlos.
authors.forename: Luiz Antonio Carlos
authors.initials: LA
authors.lastname: Bertollo
authors.affiliation: Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
authors.forename: Wagner Franco
authors.initials: WF
authors.lastname: Molina
authors.affiliation: Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, D-07743 Jena, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Liehr
authors.affiliation: Departamento de Genética e Evolução, Universidade Federal de São Carlos, Rodovia Washington Luís (SP 310) Km 235, São Carlos, SP, Brazil.
authors.forename: Marcelo de Bello
authors.initials: Mde B
authors.lastname: Cioffi
keywords: FISH; microsatellites; retrotransposable sequences; sex chromosomes