Bioinformatics Advance Access published online on June 5, 2008
Bioinformatics, doi:10.1093/bioinformatics/btn257
Hyperbolic SOM-based clustering of DNA fragment features for taxonomic visualization and classification
aAG Applied Neuroinformatics, Technical Faculty, Bielefeld University, Germany
bGraduate School Bioinformatics and Genome Research, CeBiTec, Bielefeld University, Germany
*To whom correspondence should be addressed. Christian Martin, E-mail: christian.martin{at}uni-bielefeld.de
| Abstract |
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Motivation: Modern high-throughput sequencing technologies enable the simultaneous analysis of organisms in an environment. The analysis of species diversity and the binning of DNA fragments of non-sequenced species for assembly are two major challenges in sequence analysis. To achieve reasonable binnings and classi cations, DNA fragment structure has to be represented appropriately, so it can be processed by machine learning algorithms.
Results: Hierarchical growing hyperbolic SOMs (H2SOMs) are trained to cluster small variable-length DNA fragments (0.2-50Kbp) of 350 prokaryotic organisms at six taxonomic ranks Superkingdom, Phylum, Class, Order, Genus, and Species in the Tree of Life. DNA fragments are mapped to three different types of feature vectors based on the genomic signature: Basic features, features considering the importance of oligonucleotide patterns as well as contrast enhanced features. The H2SOM classi er achieves high classi cation rates while at the same time its visualization allows further insights into the projected data and has the potential to support binning of short sequence reads, because DNA fragments can be grouped into phylogenetic groups.
Availability: An implementation of the H2SOM classi er in Matlab is provided at www.techfak.uni-bielefeld.de/ags/ani/projects/HHSOMSeqData
Contact: christian.martin{at}uni-bielefeld.de
Supplementary Information: Available at Bioinformatics online.
Associate Editor: Dr. Limsoon Wong
Received on February 22, 2008; revised on May 16, 2008; accepted on June 3, 2008