High-resolution comparative mapping among man, cattle and mouse suggests a role for repeat sequences in mammalian genome evolution.
BACKGROUND
Comparative mapping provides new insights into the evolutionary history of genomes. In particular, recent studies in mammals have suggested a role for segmental duplication in genome evolution. In some species such as Drosophila or maize, transposable elements (TEs) have been shown to be involved in chromosomal rearrangements. In this work, we have explored the presence of interspersed repeats in regions of chromosomal rearrangements, using an updated high-resolution integrated comparative map among cattle, man and mouse.


RESULTS
The bovine, human and mouse comparative autosomal map has been constructed using data from bovine genetic and physical maps and from FISH-mapping studies. We confirm most previous results but also reveal some discrepancies. A total of 211 conserved segments have been identified between cattle and man, of which 33 are new segments and 72 correspond to extended, previously known segments. The resulting map covers 91% and 90% of the human and bovine genomes, respectively. Analysis of breakpoint regions revealed a high density of species-specific interspersed repeats in the human and mouse genomes.


CONCLUSIONS
Analysis of the breakpoint regions has revealed specific repeat density patterns, suggesting that TEs may have played a significant role in chromosome evolution and genome plasticity. However, we cannot rule out that repeats and breakpoints accumulate independently in the few same regions where modifications are better tolerated. Likewise, we cannot ascertain whether increased TE density is the cause or the consequence of chromosome rearrangements. Nevertheless, the identification of high density repeat clusters combined with a well-documented repeat phylogeny should highlight probable breakpoints, and permit their precise dating. Combining new statistical models taking the present information into account should help reconstruct ancestral karyotypes.
Schibler
Laurent
L
Laboratoire de Génétique biochimique et de Cytogénétique, Département de Génétique Animale, Institut National de la Recherche Agronomique, Centre de Recherche de Jouy, 78352 Jouy-en-Josas, Cedex, France. Laurent.Schibler@jouy.inra.fr
Roig
Anne
A
Mahe
Marie-Françoise
MF
Laurent
Pascal
P
Hayes
Hélène
H
Rodolphe
François
F
Cribiu
Edmond P
EP
D000818:Animals; D002417:Cattle; D019457:Chromosome Breakage; D002874:Chromosome Mapping / Q000379:methods*; D019143:Evolution, Molecular; D016678:Genome / Q000235:genetics*; D006801:Humans; D051379:Mice; D012091:Repetitive Sequences, Nucleic Acid; D014178:Translocation, Genetic