The involvement of repetitive sequences in the remodelling of karyotypes: The Phodopus genomes (Rodentia, Cricetidae)

In this work we characterize the Phodopus roborovskii and Phodopus sungorus karyotypes, describing the constitutive heterochromatin and the telomeric repeats distribution in these chromosomes. In the two species, (peri)centromeric, interstitial and (sub)telomeric C-bands were revealed, presenting a very high colocalization with evolutionary breakpoint regions identified in these karyotypes. Also both species present telomeric sequences located interstitially (ITS), as short ITS blocks or as large ITS blocks, mainly at the (peri)centromeric heterochromatic regions. The number and degree of ITSs amplification varies greatly in the two hamsters, indicating independent evolutionary events of these repeats in each genome. The combination of the data provided interesting insights about the genome organization of these hamster species, also allowing establishing evolutionary considerations on their chromosomes. The obtained results clearly suggest an involvement of the repetitive genomic fraction in the reshaping of P. roborovskii and P. sungorus karyotypes.

► Phodopus constitutive heterochromatin highly colocalizes with evolutionary breakpoints.
► Interstitial telomeric sequences were detected in both related Phodopus genomes.
► These exhibit different patterns indicating independent molecular dynamics, despite the chromosome rearrangements.
► Involvement of repeats in the remodelling of Phodopus karyotypes was observed.