MBE Advance Access originally published online on June 16, 2004
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Mol. Biol. Evol. 21(9):1792-1799. 2004
DOI: 10.1093/molbev/msh190
© 2004 by the Society for Molecular Biology and Evolution. ISSN: 0737-4038
Evolution of Beta Satellite DNA Sequences: Evidence for Duplication-Mediated Repeat Amplification and Spreading
* Dipartimento di Anatomia Patologica e Genetica, Sezione di Genetica, Bari, Italy
Dipartimento di Biologia e Genetica per le Scienze Mediche, Milano, Italy
Dipartimento di Medicina Sperimentale, Ambientale e Biotecnologie Mediche, Monza, Italy
E-mail: raffaella.meneveri{at}unimib.it.
In this article, we report studies on the evolutionary history of beta satellite repeats (BSR) in primates. In the orangutan genome, the bulk of BSR sequences was found organized as very short stretches of approximately 100 to 170 bp, embedded in a 60-kb to 80-kb duplicated DNA segment. The estimated copy number of the duplicon that carries BSR sequences ranges from 70 to 100 per orangutan haploid genome. In both macaque and gibbon, the duplicon mapped to a single chromosomal region at the boundary of the rDNA on the marker chromosome (chromosome 13 and 12, respectively). However, only in the gibbon, the duplicon comprised 100 bp of beta satellite. Thus, the ancestral copy of the duplicon appeared in Old World monkeys (
25 to 35 MYA), whereas the prototype of beta satellite repeats took place in a gibbon ancestor, after apes/Old World monkeys divergence (25 MYA). Subsequently, a burst in spreading of the duplicon that carries the beta satellite was observed in the orangutan, after lesser apes divergence from the great apes–humans lineage (18 MYA). The analysis of the orangutan genome also indicated the existence of two variants of the duplication that differ for the length (100 or 170 bp) of beta satellite repeats. The latter organization was probably generated by nonhomologous recombination between two 100-bp repeated regions, and it likely led to the duplication of the single Sau3A site present in the 100-bp variant, which generated the prototype of Sau3A 68-bp beta satellite tandem organization. The two variants of the duplication, although with a different ratios, characterize the hominoid genomes from the orangutan to humans, preferentially involving acrocentric chromosomes. At variance to alpha satellite, which appeared before the divergence of New World and Old World monkeys, the beta satellite evolutionary history began in apes ancestor, where we have first documented a low-copy, nonduplicated BSR sequence. The first step of BSR amplification and spreading occurred, most likely, because the BSR was part of a large duplicon, which underwent a burst dispersal in great apes' ancestor after the lesser apes' branching. Then, after orangutan divergence, BSR acquired the clustered structural organization typical of satellite DNA.
Key Words: beta satellite • duplication • primate evolution
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Carmon, M. Wilkin, J. Hassan, M. Baron, and R. MacIntyre Concerted Evolution Within the Drosophila dumpy Gene Genetics, May 1, 2007; 176(1): 309 - 325. [Abstract] [Full Text] [PDF]
|
|