Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)

Gallardo, MH; González CA; Cebrian, I

Abstract

The theoretical impossibility of polyploidy in mammals was overturned by the discovery of tetraploidy in the red vizcacha rat, Tympanoctomys barrerae (2n = 102). As a consequence of genome duplication, remarkably increased cell dimensions are observed in the spermatozoa and in different somatic cell lines of this species. Locus duplication had been previously demonstrated by in situ PCR and Southern blot analysis of single-copy genes. Here, we corroborate duplication of loci in multiple-copy (major rDNAs) and single-copy (Hoxc8) genes by fluorescence in situ hybridization. We also demonstrate that nucleolar dominance, a large-scale epigenetic silencing phenomenon characteristic of allopolyploids, explains the presence of only one Ag-NOR chromosome pair in T. barrerae. Nucleolar dominance, together with the chromosomal heteromorphism detected in the G-banding pattern and synaptonemal complexes of the species' diploid-like meiosis, consistently indicates allotetraploidy. Allotetraploidization can coherently explain the peculiarities of gene silencing, cell dimensions, and karyotypic features of T. barrerae that remain unexplained by assuming diploidy and a large genome size attained by the dispersion of repetitive sequences. © 2006 Elsevier Inc. All rights reserved.

Más información

Título según WOS: Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)
Título según SCOPUS: Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)
Título de la Revista: Genomics.
Volumen: 88
Número: 2
Editorial: ACADEMIC PRESS INC ELSEVIER SCIENCE
Fecha de publicación: 2006
Página de inicio: 214
Página final: 221
Idioma: English
URL: http://linkinghub.elsevier.com/retrieve/pii/S0888754306000504
DOI:

doi:10.1016/j.ygeno.2006.02.010

Notas: ISI, SCOPUS