Scientific Axes
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Jeudi 3 Novembre 2011, Camille Berthelot (IBENS, Rennes) Print
Written by Pierre PETERLONGO   

Rearrangements occur mostly neutrally in eukaryotic genomes

10h30 Salle Minquiers

The mechanisms underlying evolutionary genomic rearrangements and
their fixation remain to date much debated. It is especially
unclear if the occurrence of rearrangements is reflected by the
current distribution of breakpoints in extant genomes, or if the
latter is the result of a selective process where only a subset
of non-deleterious rearrangements are maintained, or a
combination of both. I will present how we used ancestral genomes
reconstruction methods to infer local ancestral genomic
characteristics, and to model breakage occurrence by Poisson
regression. This work allowed us to identify parameters that have
significantly influenced the breakage probability since the
common ancestor of mammals and yeasts. Our results show that
intergene length predicts intergenic breakage probability very
well, suggesting that the breakage process is mostly neutral and
mechanistic. We also detect a small contribution from negative
selection in regions subjected to long-range genic
regulation. However, the relationship between intergenic length
and breakage is more complex than the one expected at random and
points at a possible influence of 3D nuclear organization.
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