Title
Alignment-free sequence comparison-a review.
Abstract
Motivation: Genetic recombination and, in particular, genetic shuffling are at odds with sequence comparison by alignment, which assumes conservation of contiguity between homologous segments. A variety of theoretical foundations are being used to derive alignment-free methods that overcome this limitation. The formulation of alternative metrics for dissimilarity between sequences and their algorithmic implementations are reviewed. Results: The overwhelming majority of work on alignment-free sequence has taken place in the past two decades, with most reports published in the past 5 years. Two main categories of methods have been proposed-methods based on word (oligomer) frequency, and methods that do not require resolving the sequence with fixed word length segments. The first category is based on the statistics of word frequency, on the distances defined in a Cartesian space defined by the frequency vectors, and on the information content of frequency distribution. The second category includes the use of Kolmogorov complexity and Chaos Theory. Despite their low visibility, alignment-free metrics are in fact already widely used as pre-selection filters for alignment-based querying of large applications. Recent work is furthering their usage as a scale-independent methodology that is capable of recognizing homology when loss of contiguity is beyond the possibility of alignment.
Year
DOI
Venue
2003
10.1093/bioinformatics/btg005
BIOINFORMATICS
Keywords
DocType
Volume
word frequency,genetics,information content,chaos theory
Journal
19
Issue
ISSN
Citations 
4.0
1367-4803
210
PageRank 
References 
Authors
10.93
23
2
Search Limit
100210
Name
Order
Citations
PageRank
Susana Vinga153537.72
Jonas S Almeida273142.25