NOVEL TECHNIQUES OF GRAPHICAL REPRESENTATION AND ANALYSIS OF DNA-SEQUENCES - A REVIEW

The advent of automated DNA sequencing techniques has led to an explos ive growth in the number and length of DNAs sequenced from different o rganisms. While this has resulted in a large accumulation of data in t he DNA databases, it has also called for the development of suitable t echniques for rapid viewing and analysis of the data. Over the last fe w years several methods have been proposed that address these issues a nd represent a DNA sequence in a compact graphical form in one-, two-o r three-dimensions that can be expanded as necessary to help visualize the patterns in gene sequences and aid in in-depth analysis. Graphica l techniques have been found to be useful in highlighting focal and gl obal base dominances, to identify regions of extensive repetitive sequ ences, differentiate between coding and non-coding regions, and to be indicative of evolutionary divergences. Analysis with graphical method s have also provided insights into new structures in DNA sequences suc h as fractals and long range correlations, and some measures have been developed that help quantify the visual patterns. This review present s a comprehensive study of the graphical representation methods and th eir applications in viewing and analysing long DNA sequences and evalu ates the merits of each of these from a practical viewpoint with presc riptions on domains of applicability of each method. A discussion on t he comparative merits and demerits of the various methods and possible future developments have also been included.