Colocalization of repetitive DNAs and silencing of major rRNA genes. A case report of the fish Astyanax janeiroensis

Autor(es)

Vicari, M. R. ^[1] ; Artoni, R. F. ; Moreira-Filho, O. ^[2] ; Bertollo, L. A. C. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Estadual Ponta Grossa, Dept Biol Estrutural Mol & Genet, Lab Citogenet, BR-84030900 Ponta Grossa, PR - Brazil

^[2] Univ Fed Sao Carlos, Dept Genet & Evolucao, Lab Citogenet, BR-13560 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Cytogenetic and Genome Research; v. 122, n. 1, p. 67-72, 2008.
• Citações Web of Science: 58

Resumo

The heterochromatin composition and location in the genome of the fish Astyanax janeiroensis was investigated using Chromomycin A 3 and DAPI fluorochromes and fluorescence in situ hybridization (FISH) with 18S rDNA and As51 satellite DNA probes, respectively. Distinct repetitive DNA classes were found, namely: (1) C-positive centromeric/telomeric heterochromatin, (2) NOR-associated GC-rich heterochromatin (18S(+)/GC(+)) and (3) As 51(+)/18S(+) heterochromatin colocalized on 14 distinct heterochromatic domains with attenuated fluorescence of DAPI staining (As51(+)/18S(+)/DAPI attenuated signal). Besides these fourteen associated repetitive DNAs, another eight sites with only 18S rDNA were also found, comprising altogether 22 18S rDNA sites in the genome of the species under study. Up to seven 18S rDNA sites were found to be active, i.e., were characterized as positive after silver staining (Ag-NORs). It was noteworthy that in all As51(+)/18S(+) domains the 18S rDNA were not found to be active sites due to the silencing of these genes when associated with the As51 satellite DNA in the same heterochromatic domain. The dispersion of the As51 sites in the genome of the species is hypothesized to probably originate from a transposable element. Several chromosomal and karyotype markers are similar between A. janeiroensis and A. scabripinnis, indicating a close relationship between these species. Copyright (C) 2008 S. Karger AG, Basel (AU)

• Processo FAPESP: 03/13019-0 - Diversidade de peixes residentes em cabeceiras de rios: uma abordagem cromossômica em três diferentes biomas aquáticos da Região Sul do Brasil
• Beneficiário: Marcelo Ricardo Vicari
• Modalidade de apoio: Bolsas no Brasil - Doutorado