The puzzling character of repetitive DNA in Phodopus genomes (Cricetidae, Rodentia).
Three novel repetitive DNA sequences are described, presenting a similar heterochromatic chromosomal location in two hamster species: Phodopus roborovskii and Phodopus sungorus (Cricetidae, Rodentia). Namely, two species-specific repetitive sequences (PROsat from P. roborovskii and PSUchr1sat from P. sungorus) surrounding a third one (PsatDNA), that is shared by both hamster genomes. Fiber-FISH analyses revealed that PROsat intermingles with PsatDNA in P. roborovskii and PSUchr1sat intermingles with PsatDNA in P. sungorus. A model explaining the evolution of this intricate chromosomal distribution is proposed, which can explain better the evolution of these very derivative genomes (in comparison to the ancestral Muroidea). The most plausible evolutionary scenario seems to be the expansion of a number of repeats into other's domain, most probably resulting in its intermingling, followed by the subsequent spread of these complex repeats from a single chromosomal location to other chromosomes. Evidences of an association between repetitive sequences and the chromosome evolution process were observed, namely for PROsat. Most probably, the evolutionary breakpoints that shaped PRO and PSU chromosomes (pericentric inversions and fusions) occurred within the boundaries of PROsat blocks in the ancestor. The repeats high diversity at the heterochromatic regions of Phodopus chromosomes, together with its complex organization, suggests that these species are important models for evolutionary studies, namely in the investigation of a possible relationship between repetitive sequences and the occurrence of chromosomal rearrangements and consequently, in genome evolution.
University of Trás-os-Montes and Alto Douro (UTAD), Department of Genetics and Biotechnology (DGB), Laboratory of Cytogenomics and Animal Genomics (CAG), Vila Real, Portugal.
Ana
A
Paço
University of Trás-os-Montes and Alto Douro (UTAD), Department of Genetics and Biotechnology (DGB), Laboratory of Cytogenomics and Animal Genomics (CAG), Vila Real, Portugal.|University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa, Portugal.
Filomena
F
Adega
Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10002, Zagreb, Croatia.
Nevenka
N
Meštrović
Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10002, Zagreb, Croatia.
Miroslav
M
Plohl
University of Trás-os-Montes and Alto Douro (UTAD), Department of Genetics and Biotechnology (DGB), Laboratory of Cytogenomics and Animal Genomics (CAG), Vila Real, Portugal. rchaves@utad.pt.|University of Lisboa, Faculty of Sciences, BioISI-Biosystems & Integrative Sciences Institute, Campo Grande, Lisboa, Portugal. rchaves@utad.pt.
Raquel
R
Chaves
D000818:Animals; D002871:Chromosome Banding; D033481:Chromosomes, Mammalian; D003001:Cloning, Molecular; D004276:DNA, Satellite; D040342:Genetic Structures; D016678:Genome; D023281:Genomics / Q000379:methods; D017404:In Situ Hybridization, Fluorescence; D017111:Phodopus / Q000235:genetics*; D020161:Physical Chromosome Mapping; D012091:Repetitive Sequences, Nucleic Acid
D004276:DNA, Satellite
Chromosomal evolution; Phodopus; Repetitive sequences; Rodentia