Monday, February 06, 2006
[evomech] New theory could have implications for cancer research (PR + Article)
1) Molecular Evolution (News Item)
Researchers from the University of California, San Diego (UCSD) Jacobs School of Engineering have uncovered evidence that major evolutionary changes are more likely too ccur in approximately 400 'fragile' genomic regions that account for only 5% of the human genome.
The findings, reported in the June 24, 2003, issue of the Proceedings of the National Academy of Sciences USA (PNAS), undercut the widely held view among scientists that evolutionary breakpoints - disruptions in the order of genes on chromosomes - are purely random. Apart from its implications for evolutionary theory, the study could have major implications for medical research related to diseases such as leukemia, which are caused by clinical (rather than evolutionary) chromosomal breakpoints.Full text at:
2) Human and mouse genomic sequences reveal extensive breakpoint reuse in mammalian evolution
[Pevzner & Tesler, PNAS, June '03]
The human and mouse genomic sequences provide evidence for a larger number of rearrangements than previously thought and reveal extensive reuse of breakpoints from the same short fragile regions. Breakpoint clustering in regions implicated in cancer and infertility have been reported in previous studies; we report here on breakpoint clustering in chromosome evolution. This clustering reveals limitations of the widely accepted random breakage theory that has remained unchallenged since the mid-1980s. The genome rearrangement analysis of the human and mouse genomes implies the existence of a large number of very short "hidden" synteny blocks that were invisible in the comparative mapping data and ignored in the random breakage model. These blocks are defined by closely located breakpoints and are often hard to detect. Our results suggest a model of chromosome evolution that postulates that mammalian genomes are mosaics of fragile regions with high propensityfor rearrangements and solid regions with low propensity forrearrangements.
Full text at:
Model of an Internal Evolutionary Mechanism
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