Section 10
Chapter 9,140

Origin and evolution of a major satellite DNA from South American rodents of the genus Ctenomys

Rossi, M.S.; Pesce, C.G.; Kornblihtt, A.R.; Zorzopulos, J.

Revista Chilena de Historia Natural 68(2): 171-183


ISSN/ISBN: 0716-078X
Accession: 009139492

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This article is about the origin, amplification and evolution of the major satellite DNA of South American rodents known popularly as tuco-tucos (genus Ctenomys). This satellite DNA, named RPCS, differentially amplified during the evolution of Ctenomys species, which resulted in quantitative and qualitative differences in restriction-periodicity patterns among species. A rolling circle amplification model has been proposed to explain the qualitative and quantitative differences of RPCS sequences. RPCS-related sequences were also found in octodontines, but not in echimyids; that is, they arose in the common ancestor of ctenomyines and octodontines. In situ hybridization experiments showed that RPCS is located in heterochromatic areas of the chromosomes. Finally, RPCS shows unusual features among satellite DNAs: it has a conspicuous retroviral origin. The RPCS monomer has identity with the U3 region of a retroviral LTR, including promoters and enhancers. In addition, DNase I protection assays showed that this sequences specifically bind transcription factors present in the nucleus of Ctenomys cells. The putative function that a retroviral sequence as RPCS may have played in shaping Ctenomys genome during evolution is discussed.

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