Bioinformatics Advance Access published online on July 28, 2008
Bioinformatics, doi:10.1093/bioinformatics/btn391
Is there an acceleration of the CpG transition rate during the mammalian radiation?
1Institute of Chemistry, Karl-Franzens University Graz, Graz, Austria
2Department of Computer Science and Systems Analysis and
3Department of Microbiology, Miami University, Ohio, USA
*To whom correspondence should be addressed. Dr. Martin Peifer, E-mail: peifer{at}uni-graz.at
| Abstract |
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Motivation: In this paper we build a model of the CpG dinucleotide substitution rate and use it to challenge the claim that that rate underwent a sudden mammalian-specific increase approximately ninety million years ago. The evidence supporting this hypothesis comes from the application of a model of neutral substitution rates able to account for elevated CpG dinucleotide substitution rates. With the initial goal of improving that model's accuracy we introduced a modification enabling us to account for boundary effects arising by the truncation of the Markov-field, as well improving the optimization procedure required for estimating the substitution rates.
Results: When using this modified method to reproduce the supporting analysis, the evidence of the rate shift vanished. Our analysis suggests that the CpG-specific rate has been constant over the relevant time period and that the asserted acceleration of the CpG rate is likely an artifact of the original model.
Contact: peifer{at}uni-graz.at
Associate Editor: Prof. Martin Bishop
Received on April 11, 2008; revised on July 27, 2008; accepted on July 27, 2008