Identification of two new repetitive elements and chromosomal mapping of repetitive DNA sequences in the fish Gymnothorax unicolor (Anguilliformes: Muraenidae)

Submitted: 15 December 2010
Accepted: 23 February 2011
Published: 27 May 2011
Abstract Views: 785
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Muraenidae is a species-rich family, with relationships among genera and species and taxonomy that have not been completely clarified. Few cytogenetic studies have been conducted on this family, and all of them showed the same diploid chromosome number (2n=42) but with conspicuous karyotypic variation among species. The Mediterranean moray eel Gymnothorax unicolor was previously cytogenetically studied using classical techniques that allowed the characterization of its karyotype structure and the constitutive heterochromatin and argyrophilic nucleolar organizer regions (Ag-NORs) distribution pattern. In the present study, we describe two new repetitive elements (called GuMboI and GuDdeI) obtained from restricted genomic DNA of G. unicolor that were characterized by Southern blot and physically localized by in situ hybridization on metaphase chromosomes. As they are highly repetitive DNA sequences, they map in heterochromatic regions. However, while GuDdeI was localized in the centromeric regions, the GuMboI fraction was distributed on some centromeres and was co-localized with the nucleolus organizer region (NOR). Comparative analysis with other Mediterranean species such as Muraena helena pointed out that these DNA fractions are species-specific and could potentially be used for species discrimination. As a new contribution to the karyotype of this species, we found that the major ribosomal genes are localized on acrocentric chromosome 9 and that the telomeres of each chromosome are composed of a tandem repeat derived from a poly-TTAGGG DNA sequence, as it occurs in most vertebrate species. The results obtained add new information useful in comparative genomics at the chromosomal level and contribute to the cytogenetic knowledge regarding this fish family, which has not been extensively studied.

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E. Coluccia, Università di Cagliari
Dipartimento di Biologia Animale ed Ecologia
G. Pichiri, Università di Cagliari
Dipartimento di Biologia Animale ed Ecologia
M. Nieddu, Università di Cagliari
Dipartimento di Citomorfologia, Sezione Anatomia Patologica
P. Coni, Università di Cagliari
Dipartimento di Citomorfologia, Sezione Anatomia Patologica
S. Manconi, Università di Cagliari
Dipartimento di Scienze e Tecnologie Biomediche, Sezione Biologia e Genetica
A.M. Deiana, Università di Cagliari
Dipartimento di Biologia Animale ed Ecologia
S. Salvadori, Università di Cagliari
Dipartimento di Biologia Animale ed Ecologia
R. Mezzanotte, Università di Cagliari
Dipartimento di Scienze e Tecnologie Biomediche, Sezione Biologia e Genetica

How to Cite

Coluccia, E., Pichiri, G., Nieddu, M., Coni, P., Manconi, S., Deiana, A., Salvadori, S., & Mezzanotte, R. (2011). Identification of two new repetitive elements and chromosomal mapping of repetitive DNA sequences in the fish Gymnothorax unicolor (Anguilliformes: Muraenidae). European Journal of Histochemistry, 55(2), e12. https://doi.org/10.4081/ejh.2011.e12